U.S. patent application number 12/968164 was filed with the patent office on 2011-04-07 for gasifier comprising vertically successive processing regions.
This patent application is currently assigned to Plasco Energy Group Inc.. Invention is credited to Margaret Swain, Andreas TSANGARIS.
Application Number | 20110078952 12/968164 |
Document ID | / |
Family ID | 38860207 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110078952 |
Kind Code |
A1 |
TSANGARIS; Andreas ; et
al. |
April 7, 2011 |
GASIFIER COMPRISING VERTICALLY SUCCESSIVE PROCESSING REGIONS
Abstract
The present invention provides a vertically oriented gasifier
comprising vertically successive processing regions for conversion
of carbonaceous feedstock into gas. The gasifier comprises of: one
or more processing chambers with two or more vertically successive
processing regions being distributed within said one or more
processing chambers, within each one of which a respective process
selected from the group consisting of drying, volatilization and
carbon conversion is at least partially favoured. The processing
regions are identified by temperature ranges respectively enabling
each said respective process. One or more additive input elements
are associated with the processing regions for inputting additives
to promote each said at least partially favoured process therein.
In addition, the gasifier comprises one or more material
displacement control modules adapted to control a vertical movement
of the feedstock through said processing regions to enhance each
said at least partially favoured process, one or more feedstock
inputs located near a first of said processing regions and one or
more gas outputs and one or more residue outputs.
Inventors: |
TSANGARIS; Andreas; (Ottawa,
CA) ; Swain; Margaret; (Ottawa, CA) |
Assignee: |
Plasco Energy Group Inc.
Kanata
CA
|
Family ID: |
38860207 |
Appl. No.: |
12/968164 |
Filed: |
December 14, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11758633 |
Jun 5, 2007 |
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12968164 |
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Current U.S.
Class: |
48/85.1 ;
48/197R; 48/85.2; 48/87 |
Current CPC
Class: |
C10J 3/723 20130101;
Y02E 50/10 20130101; C10J 2200/152 20130101; C10J 3/22 20130101;
C10J 2300/093 20130101; C10J 2300/1238 20130101; C10J 3/482
20130101; C10J 2300/0973 20130101; C10J 2300/0923 20130101; Y02P
20/129 20151101; C10J 3/34 20130101; C10J 3/523 20130101; C10J
2300/0956 20130101; C10J 2300/0916 20130101; C10J 2300/0946
20130101; C10J 2200/15 20130101; Y02E 50/14 20130101; C10J 2300/092
20130101 |
Class at
Publication: |
48/85.1 ; 48/87;
48/197.R; 48/85.2 |
International
Class: |
C10J 3/72 20060101
C10J003/72 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2006 |
CA |
PCT/CA2006/000881 |
Claims
1. A gasifier for conversion of carbonaceous feedstock into gas and
residue, the gasifier comprising one or more processing chambers,
two or more vertically successive processing regions being
distributed within said one or more processing chambers, within
each one of which a respective process selected from the group
consisting of drying, volatilization and carbon conversion is at
least partially favoured, said processing regions being identified
by temperature ranges respectively enabling each said respective
process; one or more additive input elements associated with said
processing regions for inputting additives to promote each said at
least partially favoured process therein; one or more material
displacement control modules adapted to control a vertical movement
of the feedstock through said processing regions to enhance each
said at least partially favoured process; one or more feedstock
inputs located near a first of said processing regions; one or more
gas outputs; and one or more residue outputs.
2. The gasifier as claimed in claim 1, wherein said processing
regions are promoted by a combination of said one or more
processing chambers and by a positioning of said one or more
additive input elements in each of said processing chambers.
3. The gasifier as claimed in claim 1, the gasifier for use in a
gasification system comprising a control system, the gasifier being
configured to operate in accordance with control parameters
provided by the control system determined in response to one or
more sensed characteristics indicative of one or more process
characteristic variations of the gasification system.
4. The gasifier as claimed in claim 3, wherein the one or more
material displacement control modules are operatively coupled to
the control system and at least partially controlled thereby to
affect a change in said one or more sensed characteristics.
5. The gasifier as claimed in claim 4, wherein said one or more
characteristics comprises one or more of a carbon content of the
product gas, a heating value of the product gas, a hydrogen content
of the product gas and a carbon monoxide content of the product
gas, and wherein said one or more material displacement control
modules are configured to adjust said vertical movement of the
feedstock through said processing regions in response to a sensed
variation in said one or more characteristics to affect a change in
same.
6. The gasifier as claimed in claim 1, the gasifier comprising two
or more vertically successive processing chambers, one or more of
said two or more vertically successive processing regions being
defined within each of said two or more processing chambers.
7. The gasifier as claimed in claim 1, the gasifier comprising one
processing chamber, said one chamber comprising two or more
additive input elements, each one of which being positioned and
operated so to promote a respective one of said two or more
vertically successive processing regions.
8. The gasifier as claimed in claim 1, wherein said gas output is
in fluid communication with a gas reformulating system for
reformulating at least some of the gas output from the
gasifier.
9. The gasifier as claimed in claim 1, wherein said gas output is
connected to a gas reformulating system via piping for
reformulating at least some of the gas output from the
gasifier.
10. The gasifier as claimed in claim 1, wherein said gas output is
in fluid communication with a gas storage tank for storing at least
some of the gas output from the gasifier.
11. The gasifier as claimed in claim 1, wherein said residue output
is in operative communication with a residue processing system for
further processing of the residue.
12. The gasifier as claimed in claim 1, wherein said residue
comprises a partially processed carbonaceous feedstock and wherein
said residue output is in operative communication with a second
gasifier for conversion of said partially processed carbonaceous
feedstock.
13. The gasifier as claimed in claim 12, wherein said second
gasifier is a vertically oriented gasifier as claimed in claim
1.
14. The gasifier as claimed in claim 13, wherein said second
gasifier is a laterally oriented gasifier.
15. The gasifier as claimed in claim 1, the feedstock being
partially processed feedstock provided from an upstream gasifier
and wherein said feedstock input is in operative communication with
a residue output of said upstream gasifier for further processing
of said partially processed carbonaceous feedstock.
16. The gasifier as claimed in claim 1, wherein said material
displacement control module is actively controlled for facilitating
exit of residue from a final one of said processing regions,
thereby indirectly controlling a downward movement of reactant
material through others of said processing regions to said final
one thereof.
17. The gasifier as claimed in claim 1, wherein said material
displacement control module comprises one or more of a rotating
arm, a rotating wheel, a rotating paddle, a rotating grate, a
moving shelf, a pusher ram, an extractor screw, and a conveyor.
18. The gasifier as claimed in claim 1, wherein the gasifier is
heated using separate, independently controlled means for heating
said processing regions.
19. The gasifier as claimed in claim 18, wherein said means for
heating comprises one or more of said additive input elements for
injection of pre-heated air.
20. The gasifier as claimed in claim 1, wherein mechanical means
are inserted into said processing chambers and adapted to mix the
carbonaceous feedstock and said additive inputs.
21. The gasifier as claimed in claim 1, wherein the feedstock input
is in operative communication with a controllable feedstock input
system.
22. The gasifier as claimed in claim 21, wherein said controllable
feedstock input system is in operative communication with a
feedstock pre-processing system.
23. The gasifier as claimed in claim 1, wherein said one or more
processing chambers are chosen from a group comprising fixed bed
processing chambers, gravity-induced vertical processing chambers,
mechanically-assisted flow processing chambers, fluidised bed
processing chambers and entrained flow processing chambers.
24. A vertically oriented gasifier for conversion of carbonaceous
feedstock into gas and residue, the gasifier comprising: one or
more processing chambers, each one of which comprising one or more
additive input elements for input of additives therein, wherein
combination of said one or more processing chambers and a
positioning of said one or more additive input elements thereof
promoting creation of two or more vertically successive processing
regions within the gasifier within each one of which a respective
process is at least partially favoured, said processing regions
being identified by temperature ranges respectively enabling each
said respective process; one or more feedstock inputs proximal to a
first of said processing regions; one or more material displacement
control modules adapted to control a vertical movement of the
feedstock through said processing regions to enhance each said at
least partially favoured process; one or more gas outputs; and one
or more residue outputs.
25. A method for converting a carbonaceous feedstock into gas and
residue comprising the steps of: providing a gasifier; creating two
or more vertically successive processing regions within said
gasifier, within each one of which a respective process selected
from the group consisting of drying, volatilization and carbon
conversion is at least partially favoured, said processing regions
being identified by temperature ranges respectively enabling each
said respective process, inputting additives within the gasifier to
promote each said at least partially favoured process; controlling
a downward movement of the feedstock through said processing
regions thereby optimizing each said at least partially favoured
process; and outputting the gas and residue from the gasifier.
26. The method as claimed in claim 25, said gasifier comprising two
or more vertically successive processing chambers, one or more of
said two or more vertically successive processing regions being
created within each of said two or more processing chambers.
27. The method as claimed in claim 25, said gasifier comprising one
processing chamber, said inputting additives step comprising
inputting additives via two or more additive input elements, each
one of which being positioned and operated so to promote a
respective one of said two or more vertically successive processing
regions.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/758,633, filed 5 Jun. 2007, which is a
continuation-in-part and claims benefit of priority to
International Patent Application No. PCT/CA2006/000881, filed 5
Jun. 2006. The contents of each of these applications is hereby
expressly incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The invention pertains to the field of gasification, and, in
particular, to a vertically oriented gasifier for conversion of
carbonaceous feedstock into a gas.
BACKGROUND
[0003] Gasification is a process that enables the conversion of
carbonaceous feedstock, such as municipal solid waste (MSW),
biomass or coal, into a combustible product gas. The product gas
can be used to generate electricity or as a basic raw material to
produce chemicals and liquid fuels.
[0004] Generally, the gasification reaction consists of feeding
carbonaceous feedstock into a heated gasifier along with a
controlled and/or limited amount of oxygen/air and optionally
steam. In contrast to incineration or combustion, which operates
with excess oxygen to produce CO.sub.2, H.sub.2O, SOx, and NOx,
gasification reactions produce a raw gas composition comprising CO,
H.sub.2, H.sub.2S, and NH.sub.3. After clean-up and appropriate
processing, the primary gasification products of interest are
H.sub.2 and CO.
[0005] Possible uses for the product gas from the gasification
reaction include: the combustion in a boiler for the production of
steam for internal processing and/or other external purposes, or
for the generation of electricity through a steam turbine; the
combustion directly in a gas turbine or a gas engine for the
production of electricity; fuel cells; the production of methanol
and other liquid fuels; as a further feedstock for the production
of chemicals such as plastics and fertilisers; the extraction of
both hydrogen and carbon monoxide as discrete industrial fuel
gases; and other industrial applications.
[0006] A number of systems have been proposed for capturing heat
produced by the gasification reaction and utilising such heat to
generate electricity, generally known as combined cycle systems.
The energy in the product gas coupled with substantial amounts of
recoverable sensible heat produced by the process throughout the
gasification system can generally produce sufficient electricity to
drive the process, thereby alleviating the expense of local
electricity consumption.
[0007] Useful feedstock can include any municipal waste, waste
produced by industrial activity and biomedical waste, sewage
sludge, coal, heavy oils, petroleum coke, heavy refinery residuals,
refinery wastes, hydrocarbon contaminated soils, biomass, and
agricultural wastes, tires, and other hazardous waste. Depending on
the origin of the feedstock, the volatiles may include H.sub.2O,
H.sub.2, N.sub.2, O.sub.2, CO.sub.2, CO, CH.sub.4, H.sub.2S,
NH.sub.3, C.sub.2H.sub.6, unsaturated hydrocarbons such as
acetylenes, olefins, aromatics, tars, hydrocarbon liquids (oils)
and char (carbon black and ash).
[0008] The means of accomplishing a gasification reaction vary in
many ways, but rely on four key engineering factors: the atmosphere
(level of oxygen or air or steam content) in the gasifier; the
configuration and dimensions of the gasifier; the internal and
external heating means; and the operating temperature for the
process. Factors that affect the quality of the product gas
include: feedstock composition, preparation and particle size;
gasifier heating rate; residence time; material feeding method (dry
or slurry feed system), the feedstock-reactant flow arrangement,
the design of the dry ash or slag removal system; whether it uses a
direct or indirect heat generation and displacement method; and the
syngas cleanup system. Gasification is usually carried out at a
temperature in the range of about 650.degree. C. to 1200.degree.
C., either under vacuum, at atmospheric pressure or at pressures up
to about 100 atmospheres.
[0009] As the feedstock is heated, water is the first constituent
to evolve. As the temperature of the dry feedstock increases,
volatilization takes place. During volatilization, the feedstock is
thermally decomposed to release tars and light volatile hydrocarbon
gases, with the formation of char, a residual solid consisting of
both organic and inorganic materials. At high temperatures (such as
above 1200.degree. C.), inorganic mineral matter is fused or
vitrified to form a molten glass-like substance called slag. The
slag is usually found to be non-hazardous and may be disposed of in
a landfill as a non-hazardous material, or sold as an ore,
road-bed, or other construction material.
[0010] If the gas generated in the gasification reaction comprises
a wide variety of volatiles, such as the kind of gas that tends to
be generated in a low temperature gasifier with a "low quality"
carbonaceous feedstock, it is generally referred to as off-gas. If
the characteristics of the feedstock and the conditions in the
gasifier generate a gas in which CO and H.sub.2 are the predominant
chemical species, the gas is referred to as syngas. Optionally, the
raw off-gas or the raw syngas is converted to a more refined gas
composition in a gas reformulating system (GRS) prior to cooling
and cleaning through a gas conditioning system (GCS).
[0011] The GRS can employ plasma heat to reformulate the
offgas/syngas by converting, reconstituting, or reforming longer
chain volatiles and tars into smaller molecules with or without the
addition of other inputs or reactants. When gaseous molecules come
into contact with the plasma heat, they disassociate into their
constituent atoms. Many of these atoms will react with other input
molecules to form new molecules, while others may recombine with
like atoms (e.g. one hydrogen atom combines with another hydrogen
atom). As the temperature of the molecules in contact with the
plasma heat decreases, all atoms fully recombine. As input gases
can be controlled stoichiometrically, output gases can be
controlled to, for example, produce substantial levels of carbon
monoxide and insubstantial levels of carbon dioxide. Alternatively,
plasma heating can be used within the gasification reaction
itself.
[0012] Plasma is a high temperature luminous gas that is at least
partially ionised, and is made up of gas atoms, gas ions, and
electrons. Plasma can be produced with any gas in this manner This
gives excellent control over chemical reactions in the plasma as
the gas might be neutral (for example, argon, helium, neon),
reductive (for example, hydrogen, methane, ammonia, carbon
monoxide), or oxidative (for example, oxygen, carbon dioxide). In
the bulk phase, plasma is electrically neutral.
[0013] The reformulated gas from the GRS may contain small amounts
of unwanted compounds and requires further treatment to convert it
into a useable product. Undesirable substances such as metals,
sulphur compounds and ash may need to be removed from the gas. This
is usually done in the gas conditioning system (GCS). For example,
dry filtration systems and wet scrubbers are often used in a GCS to
remove particulate matter and acid gases from the gas.
[0014] These factors have been taken into account in the design of
various different systems which are described, for example, in U.S.
Pat. Nos. 6,686,556, 6,630,113, 6,380,507; 6,215,678, 5,666,891,
5,798,497, 5,756,957, and U.S. Patent Application Nos.
2004/0251241, 2002/0144981. There are also a number of patents
relating to different technologies for the gasification of coal for
the production of synthesis gases for use in various applications,
including U.S. Pat. Nos. 4,141,694; 4,181,504; 4,208,191;
4,410,336; 4,472,172; 4,606,799; 5,331,906; 5,486,269, and
6,200,430.
[0015] Numerous converters are known in the art, however, a
practical efficient system has not yet achieved significant
commercial use. Most of them have been affected in the
volatilization stage by heat transfer problems attendant to the
large variance in composition and moisture content of the
feedstock. To achieve relatively steady state operation,
volatilization temperatures must be used that approach the
temperature at which slagging of inorganic material occurs within
the gasifier. However, in practise, the temperature in the gasifier
often rises above the slagging temperature due to variances in
content and moisture of the feedstock. This results in formation of
a tenaciously adhering slag coating comprising of the inorganic
components of the waste melt, on all surfaces of the gasifier
exposed to the waste.
[0016] Known vertically oriented gasifiers have utilized fixed-bed
processing chambers and moving bed processing chambers, the latter
being superior due to their ability to handle the residue without
vitrification, and include gravity-induced vertical processing
chambers, mechanically-assisted flow processing chambers, entrained
flow processing chambers, fluidised bed processing chambers and any
combination thereof. All known designs have the direction of flow
of input air counter-current to the direction of flow of the
reactant material.
[0017] Prior systems and processes in vertically oriented gasifiers
have not adequately addressed the problems that must be dealt with
on a continuously changing basis. Accordingly, it would be a
significant advancement in the art to provide a system that can
efficiently gasify carbonaceous feedstock in a manner that
maximizes the overall efficiency of the process, and/or the steps
comprising the overall process.
[0018] This background information is provided for the purpose of
making known information believed by the applicant to be of
possible relevance to the invention. No admission is necessarily
intended, nor should be construed, that any of the preceding
information constitutes prior art against the invention.
SUMMARY OF THE INVENTION
[0019] The object of the invention is to provide a vertically
oriented gasifier for conversion of carbonaceous feedstock into a
gas.
[0020] In accordance with one aspect of the invention, there is
provided a gasifier for conversion of carbonaceous feedstock into
gas and residue, the gasifier comprising: one or more processing
chambers, two or more vertically successive processing regions
being distributed within said one or more processing chambers,
within each one of which a respective process selected from the
group consisting of drying, volatilization and carbon conversion is
at least partially favoured, said processing regions being
identified by temperature ranges respectively enabling each said
respective process; one or more additive input elements associated
with said processing regions for inputting additives to promote
each said at least partially favoured process therein; one or more
material displacement control modules adapted to control a vertical
movement of the feedstock through said processing regions to
enhance each said at least partially favoured process; one or more
feedstock inputs located near a first of said processing regions;
one or more gas outputs; and one or more residue outputs.
[0021] In accordance with another aspect of the invention, there is
a provided a vertically oriented gasifier for conversion of
carbonaceous feedstock into gas and residue, the gasifier
comprising: one or more processing chambers, each one of which
comprising one or more additive input elements for input of
additives therein, wherein combination of said one or more
processing chambers and a positioning of said one or more additive
input elements thereof promoting creation of two or more vertically
successive processing regions within the gasifier within each one
of which a respective process is at least partially favoured, said
processing regions being identified by temperature ranges
respectively enabling each said respective process; one or more
feedstock inputs proximal to a first of said processing regions;
one or more material displacement control modules adapted to
control a vertical movement of the feedstock through said
processing regions to enhance each said at least partially favoured
process; one or more gas outputs; and one or more residue
outputs.
[0022] In accordance with another aspect of the invention, there is
a provided a method for converting a carbonaceous feedstock into
gas and residue comprising the steps of: providing a gasifier;
creating two or more vertically successive processing regions
within said gasifier, within each one of which a respective process
selected from the group consisting of drying, volatilization and
carbon conversion is at least partially favoured, said processing
regions being identified by temperature ranges respectively
enabling each said respective process; inputting additives within
the gasifier to promote each said at least partially favoured
process; controlling a downward movement of the feedstock through
said processing regions thereby optimizing each said at least
partially favoured process; and outputting the gas and residue from
the gasifier.
BRIEF DESCRIPTION OF THE FIGURES
[0023] FIG. 1 shows a general schematic of a vertically oriented
gasifier, in accordance with one embodiment of the present
invention.
[0024] FIG. 2 shows a general schematic of a vertically oriented
gasifier, in accordance with another embodiment of the present
invention.
[0025] FIG. 3 shows a general schematic of a vertically oriented
gasifier comprising multiple processing chambers with vertically
successive movement of the reactant material from one chamber to
the next, each with its own set of one or more additives and
off-gas extraction points, in accordance with one embodiment of the
present invention.
[0026] FIG. 4 is a representation of the processing regions in a
gasifier comprising a single processing chamber with symmetric
placement of the additive input elements, in accordance with one
embodiment of the present invention.
[0027] FIG. 5 is a representation of the processing regions in a
gasifier comprising a single processing chamber with asymmetric
placement of the additive input elements, in accordance with one
embodiment of the present invention.
[0028] FIG. 6 is a representation of the processing regions in an
ideal gasifier comprising three processing chambers, each with
symmetric placement of the additive input elements to enable the
formation of individual processing regions for drying,
volatilization and carbon conversion, in accordance with one
embodiment of the present invention.
[0029] FIG. 7 is a representation of the processing regions in a
gasifier comprising three processing chambers, each with symmetric
placement of the additive input elements enabling the formation of
processing regions with different proportion of the drying,
volatilization and carbon conversion processes occurring in them,
in accordance with one embodiment of the present invention.
[0030] FIG. 8 is a representation of the processing regions in a
gasifier with two processing chambers, with the first processing
chamber containing the drying and volatilization regions and the
second processing chamber predominantly containing the carbon
conversion region, in accordance with one embodiment of the present
invention.
[0031] FIG. 9 is a representation of the processing regions in a
gasifier with two processing chambers, with the first processing
chamber containing the drying region predominantly and the second
processing chamber containing the volatilization and carbon
conversion region, in accordance with one embodiment of the present
invention.
[0032] FIG. 10 shows the schematic of a gasification system with a
gasifier with a lateral material displacement control module
followed by a gasifier with vertical material displacement control
module, in accordance with one embodiment of the present
invention.
[0033] FIG. 11 shows the schematic of a gasification system with a
gasifier with a vertical material displacement control module
followed by a gasifier with lateral material displacement control
module, in accordance with one embodiment of the present
invention.
[0034] FIG. 12A is a cross-sectional schematic diagram of a
processing chamber with a rotating arm-based material displacement
control module, in accordance with one embodiment of the invention.
FIG. 12B is the top-view of the rotating arm-based material
displacement control module.
[0035] FIG. 13A is a perspective, cut away view of a processing
chamber using an extractor screw-based material displacement
control module, in accordance with an embodiment of the invention.
FIG. 13B shows a cross-sectional view of a slight variation where
the residue outlet is moved away from the main processing chamber
to avoid direct drop, in accordance with one embodiment of the
present invention.
[0036] FIG. 14A is a perspective, cut away view of a processing
chamber using a pusher ram-based material displacement control
module, in accordance with one embodiment of the invention. FIGS.
14B and 14C show cross-sectional views of two different processing
chambers using pusher ram-based material displacement control
modules, in accordance with one embodiment of the present
invention.
[0037] FIGS. 15A and 15B show embodiments of rotating grates that
can be used in a material displacement control module, in
accordance with different embodiments of the present invention.
[0038] FIGS. 16A and 16B show various embodiments for movement of
reactant material from one processing chamber to another in a
two-processing chamber gasifier. The material displacement control
modules employed include (a) gravity; (b) gravity with sideways top
valve; (c) gravity with hopper; (d) gravity with screw; (e)
vertical screw; (f) horizontal extractor screw; (g) vertical screw
with hopper; (h) gravity with screw and hopper; and (i) horizontal
extractor screw and hopper.
[0039] FIG. 17 is a schematic diagram of an entrained flow
processing chamber, in accordance with one embodiment of the
invention, in accordance with one embodiment of the present
invention.
[0040] FIG. 18 is a schematic diagram of an fluidized bed
processing chamber, in accordance with one embodiment of the
invention, in accordance with one embodiment of the present
invention.
[0041] FIG. 19 is a schematic diagram of a moving bed processing
chamber, in accordance with one embodiment of the invention, in
accordance with one embodiment of the present invention.
[0042] FIGS. 20A to 20D show different embodiments for the
placement of additive input elements around the processing chamber
with the depiction of the processing regions in each case, in
accordance with one embodiment of the present invention.
[0043] FIGS. 21A and 21B show different shapes of processing
chambers according to different embodiments of the invention, in
accordance with one embodiment of the present invention.
[0044] FIG. 22 shows different embodiments of feedstock input means
to the gasifier: (a) secondary feed fed to the primary feed screw;
(b) primary and secondary feed fed into a mixed hopper and conveyed
via screw to the gasifier; and (c) for two or more feed
streams.
[0045] FIGS. 23A, 23B and 23C show the connection of a
single-chamber or multi-chamber vertically oriented gasifier to a
gas conditioning system (GCS) either through or without a gas
reformulating system (GRS), in accordance with one embodiment of
the present invention.
[0046] FIGS. 24A and 24B show a system similar to that of FIG. 23,
further connected to a residue conditioning system, in accordance
with one embodiment of the present invention.
[0047] FIGS. 25A and 25B show a system similar to that of FIGS. 23
and 24, with further transfer of product gas from the residue
conditioning system either to the GRS or to the GCS.
[0048] FIG. 26A shows the use of a GCS for the product gas
generated in a residue conditioning system, in accordance with one
embodiment of the present invention.
[0049] FIG. 26B shows the use of a mini-GCS for the product gas
generated in a residue conditioning system before it is fed to a
primary GCS, in accordance with one embodiment of the present
invention.
[0050] FIG. 27 shows a modular approach for building a gasification
facility comprising of two parallel streams with independent GRS
and GCS.
[0051] FIG. 28 is a cross-sectional schematic of a cascade of a
gasifier with a single processing chamber with a plasma-based
residue conditioning system.
[0052] FIG. 29 is a cross-sectional schematic of a cascade of a
gasifier with two processing chambers with a plasma-based residue
conditioning system.
[0053] FIG. 30 shows one embodiment of a distributed control system
for a gasification facility using a gasifier, GRS, GCS, GHS and a
downstream application for the output syngas generated
upstream.
[0054] FIGS. 31 to 34 depict various combinations of how the
different function blocks processes of a gasification facility can
be constructed, wherein "1" depicts function block 1 (a gasifier),
"2" depicts a function block 2 (a residue conditioning system) and
"3" depicts function block 3 (a gas reformulating system).
DETAILED DESCRIPTION OF THE INVENTION
Definitions
[0055] As used herein, the term `about` refers to a +/-10%
variation from the nominal value. It is to be understood that such
a variation is always included in any given value provided herein,
whether or not it is specifically referred to.
[0056] The terms `carbonaceous feedstock` and `feedstock`, as used
interchangeably herein, are defined to refer to carbonaceous
material that can be used in the gasification process. Examples of
suitable feedstock include, but are not limited to, hazardous and
non-hazardous waste materials, including municipal wastes; wastes
produced by industrial activity; biomedical wastes; carbonaceous
material inappropriate for recycling, including non-recyclable
plastics; sewage sludge; coal; heavy oils; petroleum coke; heavy
refinery residuals; refinery wastes; hydrocarbon contaminated
solids; biomass; agricultural wastes; municipal solid waste;
hazardous waste and industrial waste. Examples of biomass useful
for gasification include, but are not limited to, waste wood; fresh
wood; remains from fruit, vegetable and grain processing; paper
mill residues; straw; grass, and manure.
[0057] The term `reactant material` is defined to refer to any
feedstock, including but not limited to partially or fully
processed feedstock.
[0058] As used herein, the term, `input` denotes that which is
about to enter or be communicated to any system or component
thereof, is currently entering or being communicated to any system
or component thereof, or has previously entered or been
communicated to any system or component thereof. An input includes,
but is not limited to, compositions of matter, information, data,
and signals, or any combination thereof. In respect of a
composition of matter, an input may include, but is not limited to,
influent(s), reactant(s), reagent(s), fuel(s), object(s) or any
combinations thereof. In respect of information, an input may
include, but is not limited to, specifications and operating
parameters of a system. In respect of data, an input may include,
but is not limited to, result(s), measurement(s), observation(s),
description(s), statistic(s), or any combination thereof generated
or collected from a system. In respect of a signal, an input may
include, but is not limited to, pneumatic, electrical, audio, light
(visual and non-visual), mechanical or any combination thereof. An
input may be defined in terms of the system, or component thereof,
to which it is about to enter or be communicated to, is currently
entering or being communicated to, or has previously entered or
been communicated to, such that an input for a given system or
component of a system may also be an output in respect of another
system or component of a system. Input can also denote the action
or process of entering or communicating with a system.
[0059] As used herein, the term `output` denotes that which is
about to exit or be communicated from any system or component
thereof, is currently exiting or being communicated from any system
or component thereof, or has previously exited or been communicated
from any system or component thereof. An output includes, but is
not limited to, compositions of matter, information, data, and
signals, or any combination thereof. In respect of a composition of
matter, an output may include, but is not limited to, effluent(s),
reaction product(s), process waste(s), fuel(s), object(s) or any
combinations thereof. In respect of information, an output may
include, but is not limited to, specifications and operating
parameters of a system. In respect of data, an output may include,
but is not limited to, result(s), measurement(s), observation(s),
description(s), statistic(s), or any combination thereof generated
or collected from a system. In respect of a signal, an output may
include, but is not limited to, pneumatic, electrical, audio, light
(visual and non-visual), mechanical or any combination thereof. An
output may be defined in terms of the system, or component thereof,
to which it is about to exit or be communicated from, currently
exiting or being communicated from, or has previously exited or
been communicated from, such that an output for a given system or
component of a system may also be an input in respect of another
system or component of a system. Output can also denote the action
or process of exiting or communicating with a system.
[0060] The term `residue` generally refers to the residual material
produced during processes for the gasification or incineration of
carbonaceous feedstocks. These include the solid and semi-solid
by-products of the process. Such a residue generally consists of
the inorganic, incombustible materials present in carbonaceous
materials, such as silicon, aluminium, iron and calcium oxides, as
well as a proportion of un-reacted or incompletely converted
carbon. As such, the residue may include char, ash, and/or any
incompletely converted feedstock passed from the gasification
chamber. The residue may also include materials recovered from
downstream gas conditioning processes, for example, solids
collected in a gas filtering step, such as that collected in a
baghouse filter. The residue may also include solid products of
carbonaceous feedstock incineration processes, which may come in
the form of incinerator bottom ash and flyash collected in an
incinerator's pollution abatement suite.
[0061] The term `sensing element` is defined to describe any
element of the system configured to sense a characteristic of a
process, a process device, a process input or process output,
wherein such characteristic may be represented by a characteristic
value useable in monitoring, regulating and/or controlling one or
more local, regional and/or global processes of the system. Sensing
elements considered within the context of a gasification system may
include, but are not limited to, sensors, detectors, monitors,
analyzers or any combination thereof for the sensing of process,
fluid and/or material temperature, pressure, flow, composition
and/or other such characteristics, as well as material position
and/or disposition at any given point within the system and any
operating characteristic of any process device used within the
system. It will be appreciated by the person of ordinary skill in
the art that the above examples of sensing elements, though each
relevant within the context of a gasification system, may not be
specifically relevant within the context of the present disclosure,
and as such, elements identified herein as sensing elements should
not be limited and/or inappropriately construed in light of these
examples.
[0062] The term `response element` is defined to describe any
element of the system configured to respond to a sensed
characteristic in order to operate a process device operatively
associated therewith in accordance with one or more pre-determined,
computed, fixed and/or adjustable control parameters, wherein the
one or more control parameters are defined to provide a desired
process result. Response elements considered within the context of
a gasification system may include, but are not limited to static,
pre-set and/or dynamically variable drivers, power sources, and any
other element configurable to impart an action, which may be
mechanical, electrical, magnetic, pneumatic, hydraulic or a
combination thereof, to a device based on one or more control
parameters. Process devices considered within the context of a
gasification system, and to which one or more response elements may
be operatively coupled, may include, but are not limited to,
material and/or feedstock input means, heat sources such as plasma
heat sources, additive input means, various gas blowers and/or
other such gas circulation devices, various gas flow and/or
pressure regulators, and other process devices operable to affect
any local, regional and/or global process within a gasification
system. It will be appreciated by the person of ordinary skill in
the art that the above examples of response elements, though each
relevant within the context of a gasification system, may not be
specifically relevant within the context of the present disclosure,
and as such, elements identified herein as response elements should
not be limited and/or inappropriately construed in light of these
examples.
[0063] As used herein, the term `real-time` is used to define any
action that is substantially reflective of the present or current
status of the system or process, or a characteristic thereof, to
which the action relates. A real-time action may include, but is
not limited to, a process, an iteration, a measurement, a
computation, a response, a reaction, an acquisition of data, an
operation of a device in response to acquired data, and other such
actions implemented within the system or a given process
implemented therein. It will be appreciated that a real-time action
related to a relatively slow varying process or characteristic may
be implemented within a time frame or period (e.g. second, minute,
hour, etc.) that is much longer than another equally real-time
action related to a relatively fast varying process or
characteristic (e.g. 1 ms, 10 ms, 100 ms, 1 s).
[0064] As used herein the term `continuous` is used to define any
action implemented on a regular basis or at a given rate or
frequency. A continuous action may include, but is not limited to,
a process, an iteration, a measurement, a computation, a response,
a reaction, an acquisition of data via a sensing element, an
operation of a device in response to acquired data, and other such
actions implemented within the system or in conjunction with a
given process implemented therein. It will be appreciated that a
continuous action related to a relatively slow varying process or
characteristic may be implemented at a rate or frequency (e.g.
once/second, once/minute, once/hour, etc.) that is much slower than
another equally continuous action related to a relatively fast
varying process or characteristic (e.g. 1 KHz, 100 Hz, 10 Hz, 1
Hz).
[0065] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs.
[0066] The invention provides a gasifier comprising two or more
vertically successive processing regions, within which a certain
process such as drying, volatilization or carbon conversion is at
least partially favoured. The processing regions are identified by
their different temperature ranges that enable the different
processes therein. The gasifier comprises one or more processing
chambers; the vertically successive processing regions are
distributed throughout the one or more processing chambers.
Additive input elements are associated with the processing regions
to promote the at least partially favoured process therein. Thus,
the processing regions can be considered to be promoted by a
combination of the one or more processing chambers and/or by a
positioning of the one or more additive input elements in each of
the processing chambers. The gasifier comprises one or more
feedstock inputs located near the first processing region, one or
more gas outputs, one or more residue outputs, one or more material
displacement control modules and optionally, a global control
system.
[0067] In the following discussion, the overall gasification
process will be considered to consist of three processes in
sequence: drying, volatilization and carbon conversion. It will be
appreciated that these processes are meant to be exemplary only and
should not be considered to be limited to this example as a
gasification process can be defined to consist of any two or more
processes, as can any such process can be defined to consist of one
or more sub-processes as appropriate. For the purpose of clarity
and consistency, the following will focus on describing various
embodiments of the present invention wherein the gasification
process consists of three exemplary processes described below.
[0068] (a) Drying of the Material
[0069] The feedstock delivered into the gasifier undergoes a drying
process under a temperature range between 25.degree. C. and
200.degree. C. In this temperature range, drying may also be
accompanied by minor amounts of volatilization.
[0070] (b) Volatilization of the Material
[0071] This process occurs mainly between 350.degree. C. and
800.degree. C. and may also be accompanied by a small remainder of
the drying operation as well as a substantial amount of carbon
conversion. The composition of air supplied in this region is
typically varied depending on the feedstock supplied (e.g. oxygen
enriched or depleted air).
[0072] (c) Carbon Conversion
[0073] At temperatures between 900.degree. C. and 1000.degree. C.,
the main process reaction occurring is that of carbon conversion
with the remainder of volatilization. By this time most of the
moisture has been removed from the material. The flow rate of air
supplied can be varied depending on the reactant material supplied.
Steam is also optionally added in this region.
[0074] A worker skilled in the art would readily appreciate that in
a given temperature range, all of the three processes are occurring
somewhat simultaneously and continuously, though, depending on the
temperature range, one of the processes is at least partially
favoured.
[0075] In one embodiment of the invention, the gasifier comprises
three vertically successive processing regions with the first
processing region at least partially favouring drying, the second
processing region at least partially favouring volatilization and
the third processing region at least partially favouring carbon
conversion. A worker skilled in the art will understand that the
gasifier can in general comprise of a large number of processing
regions with a different proportion of drying, volatilization or
carbon conversion occurring in each processing region. Thus, the
number of processing regions can be as many or as few as desired,
without loss of generality.
[0076] The present invention provides a vertically oriented
gasifier for conversion of carbonaceous feedstock into a fuel gas.
In general, the gasifier comprises one or more processing chambers,
each one of which comprises one or more additive input elements for
input of additives therein, wherein combination of the one or more
processing chambers and a positioning of the one or more additive
input elements, or group thereof, enable two or more vertically
successive processing regions within the gasifier, within each one
of which a respective process is at least partially favoured. The
gasifier further comprises one or more feedstock inputs for input
of the feedstock into a first of the processing regions, one or
more material displacement control modules for controlling a
downward displacement of the feedstock through the processing
regions for enhancing each respective process, one or more gas
outputs for output of gas from the gasifier, and one or more
residue outputs for output of residue from the gasifier.
[0077] For example, with reference to the embodiment of FIG. 1, a
gasifier 10 having a single processing chamber 20 may comprise two
or more distinct additive input elements 30, or groups thereof,
positioned so to respectively promote or favour processes within
respective vertically successive processing regions 40 within the
single processing chamber 20. A feedstock input 50 provides
feedstock to the first of the processing regions 40, a gas output
60 for output of gas from the gasifier 10, and a residue output 70
for output of residue from the gasifier 10. The orientations and
positions of the input and output elements for feedstock,
additives, residue and gas, in FIG. 1 are merely exemplary and any
variations in their orientations and positions are considered to be
within the scope and nature of the invention disclosed herein.
[0078] A material displacement control module operatively
controlling one or more process devices and/or mechanisms (not
shown) configured to control a vertical displacement or a rate of
vertical displacement of the material through the vertically
successive processing regions, is also provided thereby promoting
the efficient processing of the material within each of these
processing regions wherein a particular process is at least
partially favoured. For example, as will be described in greater
detail below, various devices and/or mechanisms may be controlled
by the material displacement control module to implement a downward
displacement of the material, either by direct control of material
displacement between each processing region, by controlled
extraction of material from a lowermost processing region thereby
indirectly controlling a downward displacement of material from an
uppermost processing region toward the lowermost processing region
under gravity, or using any combination thereof.
[0079] As depicted by the additives input and off-gas output
phantom lines of FIG. 1, it will be appreciated that additives may
be input in each processing region, for instance via appropriate
positioning of additive input elements adapted therefor, or
provided to a select number of these processing regions as
appropriate for a given design and embodiment of the gasifier 10.
It will also be appreciated that the additive input elements may be
actively controlled by a common response element configured to
provide a pre-selected quantity or input rate of additives (e.g.
set absolute or relative input) for a given sensed process
characteristic (e.g. process temperature, pressure, throughput,
etc.; product gas quality, quantity, composition, pressure, flow,
heating value etc.; feedstock input rate, quality, composition,
etc; and the like), or again controlled by distinct response
elements, possibly operatively linked via a same local, regional
and/or global control system.
[0080] Similarly, gas outputs may be provided for each processing
region independently, or provided by one or more cooperative gas
outputs allowing for the output of off-gases from the processing
chamber 20 from more than one processing region simultaneously.
[0081] In the embodiment of FIG. 2, a gasifier 110 may comprise two
or more processing chambers 120 vertically and operatively coupled,
each comprising one or more additive input elements 130, or groups
thereof, positioned so to respectively promote or favour processes
within respective processing regions 140 of each processing chamber
120, thereby providing a vertical succession of two or more
processing regions 140 when the processing chambers 120 are
combined. A feedstock input 150 provides feedstock to the first of
the processing regions 140, a gas output 160 provides for output of
gas from the gasifier 110, and a residue output 170 provides for
output of residue from the gasifier 110. The orientations and
positions of the input and output elements for feedstock,
additives, residue and gas, in FIG. 2 are merely exemplary and any
variations in their orientations and positions are considered to be
within the scope and nature of the invention disclosed herein.
[0082] A material displacement control module operatively
controlling one or more process devices and/or mechanisms (not
shown) configured to control a vertical displacement of the
material through the vertically successive processing regions (i.e.
between chambers and/or through the processing regions of a same
chamber), is also provided thereby promoting the efficient
processing of the material within each of these processing regions
wherein a particular process is at least partially favoured. For
example, as will be described in greater detail below, various
devices and/or mechanisms may be controlled by the material
displacement control module to implement a downward displacement of
the material, either by direct control of material displacement
between each processing region, by controlled extraction of
material from a lowermost processing region thereby indirectly
controlling a downward displacement of material from an uppermost
processing region toward the lowermost processing region under
gravity, or using any combination thereof.
[0083] As depicted by the additives input solid and phantom lines
of FIG. 2, it will be appreciated that additives will generally be
input in each processing chamber, though not exclusively, and may
also optionally be input at multiple locations within a given
processing chamber to promote definition of two or more processing
regions therein. It will also be appreciated that the additive
input elements may be actively controlled by a common response
element configured to provide a pre-selected quantity or input rate
of additives (e.g. set absolute or relative input) for a given
sensed process characteristic (e.g. process temperature, pressure,
throughput, etc.; product gas quality, quantity, composition,
pressure, flow, heating value etc.; feedstock input rate, quality,
composition, etc; and the like), or again controlled by distinct
response elements, possibly operatively linked via a same local,
regional and/or global control system.
[0084] Similarly, off-gas outputs may be provided for each
processing chamber independently, or provided by one or more
cooperative off-gas outputs allowing for the output of gas form
more than one processing chamber 120 at a time.
[0085] As will be described in greater detail with reference to a
number of illustrative embodiments of the present invention,
various combinations of processing chambers and additive input
elements therefor can be adapted to provide two or more vertically
successive processing regions as contemplated herein, wherein an
appropriate material displacement control module can be adapted for
a given embodiment to enable the controlled displacement of
material through these processing regions to enhance a processing
thereof. Such control may be imparted uniquely for each of the one
or more processing chambers of the gasifier, optionally imparting
indirect displacement of material through successive processing
regions of the same processing chamber within which more than one
processing region is defined and/or imparting a displacement of
material from a first processing chamber to a subsequent vertically
successive processing chamber of a gasifier comprising more than
one processing chamber. Alternatively, control may be imparted to
various cooperative control devices and/or mechanisms configured to
directly control displacement of material from one processing
region to another, possibly within a same processing chamber.
[0086] In one embodiment 310, and referring to FIG. 4, the
symmetrical placement of three sets of additive input elements, or
groups thereof 330, around one processing chamber 320 promotes the
substantially horizontally planar nature of the interfaces between
the resulting three processing regions 340.
[0087] In one embodiment 410, and referring to FIG. 5, three
additive input elements, or groups thereof 430, are placed
asymmetrically around the processing chamber 420 resulting in
non-horizontally planar interfaces between the resulting three
processing regions 440.
[0088] It will generally be appreciated that symmetric processing
regions may promote optimal gasification and can generally be
enhanced using mixing/agitation means (e.g. as seen in FIG. 19).
Such agitation means may comprise, for example, a rotating shaft
controlled using a motorized drive. These agitator shafts can also
be operated, in one embodiment, as a sensing element of an
integrated global control system wherein torque measurements on
these shafts can serve as an indicator of the pile height,
especially if the agitator has multi-level flights. To reduce false
reports due to the formation of agglomeration on the flights, two
agitator shafts may be used which clean each other as they rotate,
thus knocking off agglomeration. Other such agitators may be
considered herein without departing from the general scope and
nature of the present disclosure, as will be apparent to the person
of skill in the art.
[0089] In one embodiment of the invention, the gasifier comprises
two or more processing chambers each one of which comprising one or
more additive input elements. Each of the two or more processing
chambers provides a different processing region and the different
processing chambers are arranged in a vertically successive
fashion.
[0090] In one embodiment and referring to FIG. 6, the gasifier 510
comprises three processing chambers 520 each with its own additive
input elements, or groups thereof 530, positioned as to promote
definition of one processing region 540 in each processing chamber
520, wherein each of the three processes of gasification (drying,
volatilization and carbon conversion) is respectively favoured. A
worker skilled in the art will readily understand that the scenario
in FIG. 6 is ideal and in practice, each processing region however
will have different proportion of each of the gasification
processes taking place, as shown in FIG. 7, for example.
[0091] The different processing chambers can also be separately
optimized for maximal efficiencies. In one embodiment of the
invention, and referring to FIG. 8, the gasifier 710 comprises two
processing chambers 720, the first one of which is used
predominantly for drying and volatilization while the second
processing chamber is used predominantly for carbon conversion. In
this embodiment, each processing chamber 720 in the gasifier 710
exits its off-gas stream through an outlet 760 which may be kept
separated or merged. These off-gas streams may either be sent to a
storage tank or for further processing in a gas reformulating
system (GRS). In an alternate embodiment, and referring to FIG. 9,
the first processing chamber is used predominantly for drying and
the second processing chamber is used predominantly for
volatilization and carbon conversion.
[0092] Multiple processing chambers are also useful if the
feedstock has a high content of plastics. In this situation, the
use of the second processing chamber can be used to recover
additional valuable compounds such as paraffins and waxes. This can
be accomplished by operating the first processing chamber at a
lower temperature than the second processing chamber.
[0093] A worker skilled in the art will understand that while we
have described a vertically oriented gasifier as taking in
carbonaceous feedstock and outputting a residue, it can also take
in partially processed carbonaceous reactant material from another
gasifier and/or output its residue to another gasifier. In one
embodiment of the invention, and referring to FIG. 10, a
horizontally (laterally) oriented gasifier is followed by a
vertically oriented gasifier. In an alternate embodiment of the
invention, and referring to FIG. 11, a vertically oriented gasifier
is followed by a horizontally (laterally) oriented gasifier. A
worker skilled in the art will readily understand that the
orientations and positions of the inputs and outputs to the
gasifiers shown in FIGS. 10 & 11 are merely exemplary and are
not intended to limit the orientations and positions of the inputs
in an actual implementation of these systems.
Material Displacement Control Module
[0094] In contrast to standard descending bed gasifiers that rely
on the gradual consumption of the reactant material in the gasifier
to move the material downwards, the vertically oriented gasifier of
the present invention actively controls the movement of the
reactant material through the gasifier via a material displacement
control module, thus allowing the overall gasification process to
be enhanced, if not optimized for a given set of process
conditions.
[0095] As will be described in greater detail below, the material
displacement control module may further be associated with, or
integrated within a local, regional and/or global control system
adapted to actively control various elements of the gasifier in
response to sensing one or more process characteristics, either
within the gasifier, or external thereto, for example, in a
downstream process or application of the product gas. In such an
embodiment where the material displacement control module is
actively operated in conjunction with a local, regional and/or
global process control system, further refinement of the material
processing may be achieved to meet downstream needs, for example,
when the product gas, or a further processed derivative thereof, is
used for a selected downstream application. Alternatively, or in
combination therewith, the combined control of the gasification
process may be implemented so to maximise gasification of the
material, for example, to meet environmental regulations where such
regulations exist, and/or to minimise an energetic impact of the
process.
[0096] In general, the material displacement control module may be
configured to operate under pre-set operational parameters, for
example, allowing for a substantially constant residence time of
the material in each processing region, or again, may be configured
to operate under dynamically updated or generated operational
parameters adapted to optimise processing of the material to
achieve a given result. In either scenario, the material
displacement control module, and any control system operatively
coupled thereto, may comprise one or more sensing elements for
sensing one or more process characteristics, such as process
temperature(s), pressure(s), reactant composition, product gas
composition, and adjust one or more process devices, such as
mechanisms and/or devices operatively controlled by the material
displacement control module for enabling a controlled displacement
of the material through the processing regions within the gasifier,
in response to these characteristics.
[0097] In general, the primary function of the material
displacement control module is to promote the downward movement of
the reactant material through the different processing regions of
the gasifier in an actively controlled fashion in order to
facilitate efficient overall gasification. It may also optionally
incorporate means to break up residue agglomerates that can cause
jamming at the residue outlet of the gasifier. The material
displacement control module can be configured to operate one of a
variety of mechanisms or devices known in the art for enabling
displacement of material from one region to another. Examples
include, but are not limited to rotating arms, rotating wheels,
rotating paddles, moving shelves, pusher rams, screws, conveyors,
and combinations thereof.
[0098] In addition to controlling the displacement of material
through the gasifier, the material displacement control module can
also be specifically optimized to also minimize the carbon content
in the residue. In one embodiment of the invention, this is
achieved using a plug flow pattern for the movement of the reactant
material and a total control over the residue removal rate.
[0099] The factors involved in the choice of a particular type of
device or mechanism operated by the material displacement control
module include but are not limited to: (a) controllability &
speed: how well can the flow of the reactant material through the
gasifier be controlled accurately; (b) variance in reactor flow: if
additives are added below the material displacement control module,
is there a disruption to the flow and is the disruption manageable;
and/or (c) power requirements and durability: how much energy and
maintenance is required for proper operation of the device or
mechanism, e.g. rotating grates require more maintenance than
screws and pusher rams when properly designed.
[0100] FIG. 12 depicts one embodiment of the invention in which the
material displacement control module comprises a rotating paddle 81
at the bottom of each processing chamber 20 which moves the
reactant material out of the processing chamber 20 through a small
residue outlet 70. To avoid the waste of partially/unprocessed
reactant material through the residue outlet 70 by a direct drop, a
hat covering 82 is placed over the residue outlet 70. Limit
switches may be optionally used to control the speed of the bar
rotation and thus the rate of removal of residue. A worker skilled
in the art will readily understand that in embodiments where the
multiple processing chambers are operatively coupled, a rotating
paddle may be used at the bottom of only the lowermost processing
chamber and the reactant material passes from the uppermost
processing chamber to the lowermost processing chamber by the
action of gravity.
[0101] FIG. 13A depicts one embodiment of the invention in which
the material displacement control module comprises a set of
extractor screws 83 at the bottom of each processing chamber 20
which moves the residue out of the processing chamber 20. Serration
on the edge of the extractor screw flight helps in the breaking up
of the residue agglomerations that could otherwise result in
jamming at the residue outlet 70 of the gasifier 10. A hat covering
82 is not required if the residue outlet 70 is moved away from the
processing chamber 20, as for the embodiment shown in FIG. 13B.
Limit switches may be optionally used to control the speed of the
screws and thus the rate of removal of residue. A worker skilled in
the art will readily understand that in embodiments where the
multiple processing chambers are operatively coupled, a set of
extractor screws may be used at the bottom of only the lowermost
processing chamber and the reactant material passes from the
uppermost processing chamber to the lowermost processing chamber by
the action of gravity.
[0102] FIG. 14 depicts one embodiment of the invention in which the
material displacement control module comprises a single thin pusher
ram 85 for each processing chamber 20 which moves the residue out
of the processing chamber 20 through a small residue outlet 70.
Depending on the position of the residue outlet 70, a hat covering
82 may or may not be required as shown in FIG. 14. Limit switches
may be optionally used to control the length of the pusher ram
stroke and thus the amount of residue moved with each stroke. The
use of thin, pusher rams 85 is unlike lateral transfer gasifiers
where the rams used are typically carrier-rams that carry large
amounts of reactant material from one processing region to another.
As the pusher rams 85 used are thin, only a small amount of residue
is moved out of the processing chamber 20. A worker skilled in the
art will readily understand that in embodiments where the multiple
processing chambers are operatively coupled, a pusher ram may be
used at the bottom of only the lowermost processing chamber and the
reactant material passes from the uppermost processing chamber to
the lowermost processing chamber by the action of gravity.
[0103] In one embodiment of the invention with one or more
processing regions being promoted by one or more additive input
elements within each processing chamber, the material displacement
control module may comprise an array of one or more pusher rams
within each processing chamber, each of which is used to actively
control the movement of the reactant material from one processing
region to the next until the final pusher ram pushes the residue
out of the processing chamber. Thus, the reactant material is
actively controlled through the entire height of a single
processing chamber. A worker skilled in the art will understand
that such a material displacement control module can enable setting
up of different `residence times` in the different processing
regions even within the same processing chamber.
[0104] In embodiments where the material displacement control
module comprises a moving element and a guiding element, suitable
moving elements include, but are not limited to, a shelf/platform,
pusher ram, plow, screw element or a belt. The guide element can
include one or more guide channels located in the bottom wall of
the processing chambers, guide tracks or rails, guide trough or
guide chains. Alternatively, the guide element can include one or
more wheels or rollers sized to movably engage the guide element.
In one embodiment of the invention, the guide engagement member is
a sliding member comprising a shoe adapted to slide along the
length of the guide track. Optionally, the shoe further comprises
at least one replaceable wear pad.
[0105] The material displacement control module may be powered
using a motor and drive system, or other such means as readily
known in the art. In one embodiment the motor means is an electric
variable speed motor which drives a motor output shaft selectably
in the forward or reverse directions. Optionally, a slip clutch
could be provided between the motor and the motor output shaft. The
motor may further comprise a gear box.
[0106] Alternatively, operation of the material displacement
control module can be implemented by a hydraulic or pneumatic
system, chain and sprocket drive, or a rack and pinion drive. These
methods of translating the motor rotary motion into linear motion
have the advantage that they can be applied in a synchronized
manner at each side of the material displacement control module
(e.g. a pusher ram) to assist in keeping the mechanism aligned and
thus minimize the possibility of jamming. In one embodiment, the
use of two chains provides a means of maintaining angular alignment
without the need for precision guides.
[0107] For the embodiments using two processing chambers, FIG. 16
shows a variety of different devices and/or mechanisms that can be
used by the material displacement control module for displacement
of reactant material from one processing chamber to another. A
worker skilled in the art will understand that the options in this
figure are merely exemplary and other appropriate designs for such
devices/mechanisms can be considered to be within the scope and
nature of the invention disclosed herein.
Processing Chambers
[0108] The vertically oriented gasifier comprises one or more
processing chambers. The processing chamber can be chosen from a
group consisting of fixed-bed processing chambers, gravity-induced
vertical processing chambers, mechanically-assisted flow processing
chambers, entrained flow processing chambers, and fluidised bed
processing chambers, to name a few.
[0109] In fixed-bed processing chambers known to a worker skilled
in the art, the feedstock enters the system from the top and rests
on a surface through which input gas, such as heated air or steam
(or other additives), may be communicated. The input gas passes
through the feedstock bed in a counter-current fashion, from the
bottom and all output gases, including off-gas, syngas, cooled air
and steam, or volatiles, leaves the processing chamber through
vents or other outlets at the top of the processing chamber. Any
residue such as ash or char passes through the communicable surface
and exits the processing chamber through the bottom portion.
[0110] In entrained flow processing chambers 22, with reference to
FIG. 17, the input gas travels in a counter-current flow relative
to the feedstock. Here, the feedstock is at least partially
suspended by the movement of the additives, thereby promoting a
more distributed contact between the input and the feedstock. The
reaction occurs as the reactant material moves downward, driven by
gravity, in opposition to the direction of travel of additives, the
flow of which has sufficient force to partially suspend the
descending feedstock. Output gases, including off-gas, syngas,
cooled air, steam and other volatiles, exit at the top of the
processing chamber, and the resulting residue exit at the
bottom.
[0111] In fluidized bed processing chambers 24, with reference to
FIG. 18, the feedstock is suspended in the upward moving additives
similar to entrained flow processing chambers. The distinction
however lies in the behaviour of the feedstock in the bed. In
fluidized beds, the additives enter the processing chamber at
velocities that greatly overcome any gravitational force, and the
feedstock bed moves in a much more turbulent manner thereby causing
a more homogeneous reaction region and behaving in a fashion
similar to that of a turbulent fluid even though the feedstock may
in fact be solid. The additives enter the processing chamber from
the bottom, passes counter-current to the feedstock and output
gases, including off-gas, syngas, cooled air and steams, or
volatiles, leave the processing chambers at the top.
[0112] In one embodiment of the invention using a moving-bed
processing chamber 26, the processing chamber 26 comprises a
feedstock input proximal to the top of the processing chamber, two
or more additive input elements for injection of pre-heated air and
positioned such that each promotes determination of a different
processing region, a product gas outlet, a residue outlet and an
actively controlled material displacement control module at the
base of the processing chamber. In one embodiment and referring to
FIG. 19, separate additive input elements are also reserved for
addition of steam into the processing chamber. Also, mixing
mechanisms 27 may be used to promote enhanced interaction between
the additives and the reactant material within the processing
chamber.
[0113] In one embodiment of the invention using moving-bed
processing chambers, the gasifier comprises two or more moving-bed
processing chambers, each with an additive input element, or group
thereof, for injection of pre-heated air at the bottom of the
processing chamber. The injection of pre-heated air from the bottom
enables the oxidation of char formed near the bottom of the
processing chamber. The counter-current flow of the pre-heated air
with respect to the feedstock also enhances the energy utilization.
As the pre-heated air passing through the moving feedstock bed
loses its temperature, a temperature gradient is formed within the
processing chamber that is consistent with the higher temperatures
needed for the latter processes of gasification.
[0114] In one embodiment of the invention using moving-bed
processing chambers, the one or more additive input elements for
each processing chamber are distributed all around the processing
chamber. This distribution of a plurality of input elements allows
finer control of the processes of gasification. FIGS. 20A to 20D
show other embodiments of the invention with differences in the
placement and type of additive input elements. The general shapes
of the processing regions for each case are also shown.
[0115] The processing chambers used can be of any shape so long as
the internal volume is sufficient to accommodate the appropriate
amount of reactant material for the designed residence time, and
sufficient for a reasonable gas superficial velocity to be
attained. In one embodiment of the invention, the processing
chamber is a refractory-lined cylinder and its length is between
about 1 and 3 times its diameter. In one embodiment, its length is
between about 1 and 2 times its diameter. In one embodiment, its
length is about 1.5 times its diameter.
[0116] In one embodiment of the invention, the processing chamber
has a cylindrical outer wall and a refractory-lined, downward
sloping, inner walls. FIGS. 21A and 21B show a few more possible
shapes for the processing chamber. Other appropriate shapes will be
apparent to a worker skilled in the art.
[0117] The refractory lining protects the processing chamber from
the effects of high temperatures and corrosive gases and minimizes
unnecessary loss of heat from the process. The refractory material
is a conventional refractory material, which is well-known to those
skilled in the art and which is suitable for use for a high
temperature e.g. up to about 1800.degree. C., un-pressurized
reaction. Examples of such refractory material include, but are not
limited to, high temperature fired ceramics, i.e., aluminum oxide,
aluminum nitride, aluminum silicate, boron nitride, zirconium
phosphate, glass ceramics and high alumina brick containing
principally, silica, alumina, chromia and titania. To further
protect the processing chamber from the impact of corrosive gases,
it may be lined with a membrane. Such membranes are known in the
art and as such a worker skilled in the art would readily be able
to identify appropriate membranes based on the gasifier
requirements.
[0118] The roof or upper portion of the processing chamber should
also be designed for the optimal flow and residence time of gas.
The roof portion can be flat, domed or other practical
configurations that promote the flow of gas through the processing
chamber, and thus the avoidance of dead (a.k.a `cold`) spots.
[0119] The physical design characteristics of a processing chamber
are determined by a number of factors that can be readily
determined by one skilled in the art. For example, the internal
configuration and size of the processing chamber are dictated by
the operational characteristics through analyses of the chemical
composition of the input feedstock to be processed. Other design
factors include the type of heating means used and the position and
orientation of the heating means used. These heating means are
generally positioned within the processing chamber at the desired
depth in order to concentrate the high temperature processing
region where it will be most effective, while at the same time
minimizing heat losses. Sometimes, other additives such as steam
are added into the gasifier in addition to the pre-heated air, to
improve the quality of the product syngas. The position,
orientation and number of the injection ports for these additional
additives also have to be considered in the design of the
processing chamber to ensure that they are injected where they will
promote efficient reaction to achieve the desired conversion
result.
[0120] A worker skilled in the art will readily understand that the
one or more processing chambers used in the vertically oriented
gasifier can each use different refractory materials, different
shapes, different sizes and different material displacement control
modules as suitable for the processing done within that
chamber.
[0121] Various computer-based simulation and modeling tools can
facilitate the physical design of the processing chamber by taking
into account factors such as efficient heat transfer, gas flow,
mixing of additives, etc. Computer-based tools virtually eliminate
the need for experimentation prior to preliminary system design and
provide rapid confirmation of process characteristics and
efficiency with any input waste stream. They also permit
interactive iteration to optimize operational characterization for
any particular system prior to system commissioning and facilitate
real-time optimization of processes for non-homogeneous materials
based on product gas characterization as input.
[0122] One such simulator is the Chemical Process Simulator, as
detailed in U.S. Pat. No. 6,817,388 (incorporated by reference). It
uses the principle of minimization of Gibb's free energy to allow
prediction of the product gas components at a specific temperature
and specific set of input parameters. In general, the simulator
consists of three main computational blocks: [0123] a. An Ideal
Reaction Model: This calculates the ideal, steady state equilibrium
composition of the product gas, by minimizing the Gibbs free energy
of the product chemical species in adiabatic, isobaric equilibrium.
A generalized Gibbs minimization approach is used here to find the
equilibrium composition of arbitrary large systems without the need
to write equilibrium reactions. [0124] b. A Carbon Deposition
Model: This calculates the amount of soot (solid Carbon C(s))
formed, or the amount of steam needed to eliminate soot formation
by comparing the input composition vs. equilibrium curves. This
model can also be used to recursively solve for the amount of water
that must be added in order to reduce the amount of solid carbon
formed. [0125] c. A Non-Ideal Reaction Model: This determines the
amount of methane, acetylene and ethylene that is formed in excess
of the ideal as calculated by multiplying the amount of Carbon in
the system by experimentally derived ratios. This approximates the
result of non-total decomposition of long-chain hydrocarbons or
polymers.
[0126] In addition to using the Chemical Process Simulator, flow
modeling of the processing chamber may also be used in the design
process to ensure proper mixing of the process inputs, to analyze
impact of the kinetic effects, and to adjust the reaction
temperature profile within the simulator. Flow modeling results
also assist refractory design since all operating characteristics
at the refractory surface can readily be identified.
[0127] Optionally, and as mentioned earlier, one or more of the one
or more processing chambers of the gasifier may comprise a mixing
means for ensuring efficient exposure of the reactant material to
the pre-heated air thus allowing efficient gasification. The mixing
means prevents gas channelling, a condition where the additive
inputs such as pre-heated air burns a path through the bed,
resulting in more pre-heated air travelling down that `channel`
avoiding the reactant material completely. The passage of
pre-heated air into the gas phase, also called breakthrough, can
cause rapid combustion with gas phase combustibles, agglomeration
of the reactant material and channel burning. Good mixing also
stabilizes the gas composition and reduces the risk of downstream
gas explosion.
[0128] Gasification requires heat and an oxidant such as oxygen or
steam. Heating can occur either directly by the heat released due
to partial oxidation of the feedstock or indirectly by use of a
heat source known in the art.
[0129] In one embodiment of the invention, the heat source is
pre-heated air added into the processing chambers through the
additive input elements. The air is either obtained from air
heaters or heat exchangers, both of which are known to a worker
skilled in the art and fed through to each processing region using
an independent air feed and distribution system such as an air box.
Alternatively, the indirect heat source could either be circulating
hot sand or an electrical heating element.
[0130] In order to facilitate initial start up of the gasifier, the
processing chambers can include access ports sized to accommodate
various conventional burners, for example natural gas or propane
burners, to pre-heat the gasifier.
[0131] In addition, the processing chambers can further comprise
one or more service ports to allow for entry for maintenance and
repair. Such ports are known in the art and can include sealable
port holes of various sizes. In one embodiment, access to the
processing chamber is provided by a manhole at one end which can be
closed by a sealable refractory lined cover during operation. In
one embodiment of the invention, a manhole is placed on both ends
of the processing chamber for maintenance.
Additive Input Elements
[0132] As mentioned earlier, additives may be added to each of the
one or more processing chambers of the vertically oriented gasifier
to facilitate efficient conversion of feedstock into product gas.
The type and quantity of the additives is selected to optimize the
process reactions while maintaining adherence to regulatory
authority emission limits and minimizing operating costs. The
different types of additive input elements include but are not
limited to air, oxygen-enriched air, oxygen, steam and ozone. The
additive input elements play a key role in determining the
temperatures within the processing chambers and thus the extents of
the processing regions wherein different processes are at least
partially favoured.
[0133] Air or oxygen input can be used to maximize carbon
conversion (i e, minimize free carbon) and to maintain the optimum
processing temperatures while minimizing the cost of input heat.
The quantity of both additives can be established and rigidly
controlled as identified by the outputs for the feedstock being
processed. The amount of air injection is established to minimize
the cost of heating while ensuring the overall process does not
approach any of the undesirable traits associated with incineration
(such as unwanted dioxins, furans, NOx, SOx in product gas, metals
in ash and lower carbon conversion), and satisfies the emission
standards requirements of the local area.
[0134] Steam inputs promote sufficient free oxygen and hydrogen to
maximize the conversion of decomposed elements of the feedstock
into product gas and/or non-hazardous compounds. As the conversion
of the reactant material to gas via reaction with steam is an
endothermic one, it can serve to balance out the endothermic nature
of the reaction via air. In addition, steam provides additional
hydrogen for the proper balancing of C, H, O reactions.
[0135] In some embodiments of the invention, a secondary feedstock
stream is also introduced as a process additive. This feedstock
stream can be dynamically manipulated by the global control system
depending on the downstream parameters of the gasifier such as the
quality of the product gas, pressure etc as sensed by the sensing
elements. A typical secondary feedstock is high carbon feedstock
such as plastics.
[0136] Each of the processing chambers therefore, may include a
plurality of additive input elements that include inlets for steam
injection and/or air injection. The steam inlets can be
strategically located to direct steam into high temperature regions
and into the product gas mass just prior to its exit from the
processing chamber.
[0137] The additive input elements can be strategically located to
ensure full coverage into the processing regions. In one
embodiment, they are located proximal to the floor of the
processing chamber. Alternatively, they are located either in the
floor of the processing chamber or are distributed all around the
walls of the processing chamber. In embodiments in which pre-heated
air is used as the gasifier heating means, additional air/oxygen
injection input elements may optionally be included.
[0138] The actual location of the additive input elements may
determined based on any number of the following factors: (a)
maximize heat transfer; (b) maximize contact with carbon; (c)
minimize pressure loss; (d) avoid pluggage; (e) minimize potential
for gas channelling.
[0139] For embodiments of the invention where additives are added
from the top of the processing chamber, the gases added at the top
may help dry the wet carbonaceous feedstock at the top of the bed
or help in the distribution of the material by the use of jets (by
spraying the material around the top of the pile, rather than the
use of mechanical agitation means). If air or hot steam is added at
the top, the temperature of the product gas increases resulting in
the breakdown of tars in the gas phase. Alternatively, the addition
of low temperature steam or nitrogen (or other liquid fluids)
lowers the gas temperatures and protects the downstream equipment.
The major drawback of having the additive input elements on the top
of the chamber is however the risk of dilution of the product
gas.
[0140] For embodiments of the invention where additives are added
from the bottom of the processing chamber, the residence time of
the additives in the processing chamber is maximised, which can be
beneficial in low-temperature systems with slower reactions. While
poor designs run a high risk of producing slag, agglomerations,
etc. that interfere with operations, proper design can reduce the
likelihood of these problems. The injection of additives at the
bottom promotes that the entire processing chamber is affected and
that the carbon is removed from the ash before it exits the
processing chamber.
[0141] For embodiments of the invention where additives are added
from the sides of the processing chamber, even distribution of
additives and hence more stable reactions are promoted. This design
also evens out the processing regions and reduces the concentration
of some additives (such as oxygen or ozone) to avoid localized
combustion or agglomeration. However, the main drawback is that the
additives injected along the sides do not reach the middle of the
processing chamber unless high flow rates are used which tend to
fluidize the bed or create hot spots near the walls. Agitators can
be used to promote mixing of the reactant material from the middle
with that of the sides.
Feedstock Input Means
[0142] The vertically oriented gasifier includes a material feeder
system comprising one or more input feed ports catered to any
physical characteristics of the input feedstock, each of which feed
directly into the gasifier. In one embodiment of the invention, the
material feeding subsystem consists of a feed hopper and a screw
conveyor used to transport feedstock to the gasifier. In some
embodiments of the invention, the material fed into the vertically
oriented gasifier can be partially processed reactant material from
an upstream gasifier. The feed hopper acts as a buffer for the
material ready to be fed into the gasifier. The hopper can
optionally have high and low level indicators that control the flow
into the hopper and are optionally under the control of the process
controller to match the feed rate to process demands.
[0143] Optionally, referring to FIG. 22A, the material feeding
subsystem can further comprise an additional entry to accept a
secondary feed (usually high carbon feedstock such as shredded
plastic), thereby enabling quick response to process demands for
higher or lower carbon input to meet the required gas quality for
the downstream applications.
[0144] Referring to FIG. 22, various embodiments of the invention
can be envisioned, whereby the different feed streams are either
mixed together in a common hopper before insertion into the
gasifier or not. Optionally, the gasifier has a separate feeding
subsystem for feeding the high carbon feedstock into the gasifier.
Also, a more general case can be considered where there are more
than two feed streams as well.
[0145] In one embodiment of the invention, the material feeding
system consists of a rectangular feedhopper and a hydraulic
assisted ram. A gate may be installed in the middle of the feed
chute to act as a heat barrier between the processing chamber and
the feedhopper. Limit switches on the feeder control the length of
the ram stroke so that the amount of material fed into the
processing chamber with each stroke can be controlled.
[0146] In one embodiment of the invention, the primary material
feeding system may also be modified to accommodate the feeding of
boxes, the form in which hospital biomedical type waste is provided
for processing. A rectangular double door port will permit the
boxes to be fed into the primary feed hopper where the hydraulic
ram can input them into the processing chamber.
[0147] In one embodiment of the invention, an auger can be inserted
hydraulically into the processing chamber to provide a granular
waste material feed. In addition, ram, rotary valve, top gravity
feed, are examples of other feeders that can be used in the present
context to facilitate the introduction of desired feedstocks. In
addition, liquids and gases can be fed into the processing chamber
simultaneously through their own dedicated ports.
[0148] Optionally, the feedstock will pass through a pre-processing
system before being fed into the feedstock input means. The
pre-processing subsystem may comprise a shredder to reduce the
as-received feedstock to a size more suitable for processing. As,
components of the feedstock may include materials large enough to
jam the shredder, the shedder is optionally equipped to stop when a
jam is sensed, automatically reverse to clear the jam and then
restart. If a jam is still detected the shredder will shut-down and
send a warning signal to the controller. Appropriate shedder and
shedder designs are known in the art.
[0149] The pre-processing subsystem may also include a magnetic
pick-up located above the conveyor to avoid the undesirable feeding
of excessive amounts of metal through the gasifier. Appropriate
magnetic pick-ups are known in the art and consist of a powerful
magnet over a pick conveyor belt to attract any ferrous metal that
may be present in the shredded waste. Optionally, a non-magnetic
belt can run across the direction of the pick conveyor, between the
magnet and the feedstock so that any metal attracted to the magnet
gets moved laterally away from the feedstock stream. When the metal
has been moved away from the magnet it can be dropped onto a pile
that is either disposed or sold.
Gas Outlet
[0150] In one embodiment of the invention, the off-gas generated in
each processing chamber 20 is taken out using a gas outlet 60 that
is at the top of the processing chamber 20. The off-gas streams
from the different processing chambers 20 may be kept separate or
merged before being sent either to a storage tank for future use or
for further processing in a gas reformulating system (GRS) 92, as
shown in FIG. 23C. Alternatively, the gas outlet is placed at the
bottom of the processing chamber and the product gas is drawn out
using a blower kept downstream or other suction means as known in
the art. A worker skilled in the art will readily understand that
the placement of the gas outlet at other positions within the
processing chambers are all considered to be within the scope of
the invention, even if not explicitly mentioned herein.
[0151] In one embodiment of the invention, the gasifier is
connected to a gas reformulating system (GRS) 92 either directly or
via piping for the reformulating of input gas derived from
gasification of carbonaceous feedstock into reformulated gas of a
defined chemical composition. In particular, the gas reformulating
system uses torch heat from one or more plasma torches to
dissociate the gaseous molecules thereby allowing their
recombination into smaller molecules useful for downstream
application, such as energy generation. At the high temperatures,
typically 900.degree. C.-1200.degree. C., provided by the plasma
torches, `tar cracking` usually occurs to eliminate the tar as
well. The system may also comprise gas mixing means, process
additive means, and a control system with one or more sensors, one
or more process effectors and computing means to monitor and/or
regulate the reformulating reaction. Referring to FIG. 23, the
syngas produced in the GRS may be sent to a gas conditioning system
(GCS) 90 and/or a gas homogenization system (GHS) and/or a storage
tank.
[0152] In other embodiments of the invention, low temperature gas
reformulating systems can be used which do not result in tar
cracking but result in the conversion of the gas to a different
composition tailored for a particular downstream application.
[0153] The GCS 90 serves to remove particulate matter and other
impurities from the syngas while the GHS serves to smooth out any
time variations in the composition and pressure of the syngas by
providing adequate mixing means and residence time within a
homogenization chamber. A storage tank is optionally used if the
conditioned, homogenized syngas needs to be stored for future use.
Otherwise, the conditioned, homogenized syngas can be used for
downstream applications such as gas engines, boilers etc. Excess
syngas can also be disposed of safely using a flare stack.
Residue Outlet
[0154] The residue outlet 70 is used to remove the residue out of
the final processing region 40 of the gasifier 10. The
configurations in which the residue exit the processing chamber are
dependent on the design and function of the subsequent process and
can be readily determined by one skilled in the art.
[0155] As mentioned earlier, the residue is removed from the
gasifier by the material displacement control module. In different
embodiments of the invention, the residue can be removed into, for
example, an ash collection gasifier or to a water tank for cooling
as is known in the art, from where it is transmitted through a
conduit under control of a valve, to a point of discharge. In one
embodiment of the invention, the residue from the vertically
oriented gasifier is sent to another gasifier for further
gasification. This is useful if the vertically oriented gasifier is
not able to achieve thorough volatilization and carbon
conversion.
[0156] In one embodiment of the invention and referring to FIG. 24,
the residue is moved to a residue conditioning system 94 which is
either directly connected to the gasifier 10 or connected via a
conveyor. In the residue conditioning system 94, plasma arc heating
is used to convert the residue (char, ash) to slag by raising the
temperature of the residue to the level required for complete
melting and homogenization to guarantee trouble free, continuous
and automatic (i.e. unattended) slag removal. Other heating
mechanisms can also be used in other embodiments of the residue
conditioning system. The molten slag is quenched in a water tank to
form a vitreous, solid slag that can either be used in the
construction industry or disposed off in a non-hazardous manner in
landfills. Referring to FIG. 25, any product gases generated in the
residue conditioning system 94 is sent to the GCS 90 either after
passing through the GRS 92 or otherwise.
[0157] Additionally, referring to FIG. 26, the residual particles
collected in the GCS 90, can be sent back to the residue
conditioning system 94 for conversion to molten slag and quenching.
For the case of the transfer of the product gas from the residue
conditioning system 94 to the GCS 90 without passing through the
GRS 92, the gas can reach the GCS 90 either directly or through a
secondary GCS 96, as shown in FIG. 26.
[0158] In one embodiment of the invention and referring to FIG. 27,
the overall system is constructed using a modular approach where
the product gas output from the plurality of processing chambers 20
of the gasifier are not combined to pass through a single GRS and
GCS but is split up into two parallel streams, each with its own
GRS 92 and GCS 90. A worker skilled in the art will understand that
FIG. 27 is merely exemplary and that other designs of the overall
systems using interconnections of the different components of the
multiple parallel processing streams can be considered to be within
the scope and nature of the invention disclosed herein.
[0159] FIGS. 28 and 29 shows the particular implementation of the
gasifier where a residue conditioning system 94 based on a
plasma-torch 95 is interfaced in a vertically successive fashion to
a gasifier comprising either one or two vertically successive
processing chambers 20.
[0160] As mentioned earlier, the gasifier 10 of the invention can
be combined with various other systems, such as a residue
conditioning system 94, gas reformulating system 92, gas
conditioning system 90, gas homogenization system, to form a
complete gasification facility. This facility will take in
carbonaceous feedstock and convert it into a refined, conditioned
and homogenized syngas that can be used for various downstream
applications. The overall gasification facility can be controlled
using a global control system 98 as described above to ensure that
the overall process meets the requirements set by the particular
downstream application and by the relevant regulatory standards.
One embodiment of a control system for an overall gasification
facility is shown in FIG. 30.
Control System
[0161] A control system 98 is generally provided to control one or
more processes implemented in, and/or by, the vertically oriented
gasifier, or affecting any downstream process or application of the
gas produced thereby, and/or provide control of one or more process
devices contemplated herein for affecting such processes. In
general, the control system may operatively control various
processes related to the vertically oriented gasifier and/or
related to one or more global, upstream and/or downstream processes
implemented within a gasification system comprising such a
gasifier, and thereby adjusts various control parameters thereof
adapted to affect these processes for a defined result. Various
sensing elements and response elements may therefore be distributed
throughout the controlled system(s), or in relation to one or more
components thereof, and used to acquire various process, reactant
and/or product characteristics, compare these characteristics to
suitable ranges of such characteristics conducive to achieving the
desired result, and respond by implementing changes in one or more
of the ongoing processes via one or more controllable process
devices.
[0162] The control system generally comprises, for example, one or
more sensing elements for sensing one or more characteristics
related to the system(s), processe(s) implemented therein, input(s)
provided therefor, and/or output(s) generated thereby. One or more
computing platforms are communicatively linked to these sensing
elements for accessing a characteristic value representative of the
sensed characteristic(s), and configured to compare the
characteristic value(s) with a predetermined range of such values
defined to characterise these characteristics as suitable for
selected operational and/or downstream results, and compute one or
more process control parameters conducive to maintaining the
characteristic value within this predetermined range. A plurality
of response elements may thus be operatively linked to one or more
process devices operable to affect the system, process, input
and/or output and thereby adjust the sensed characteristic, and
communicatively linked to the computing platform(s) for accessing
the computed process control parameter(s) and operating the process
device(s) in accordance therewith.
[0163] In one embodiment, the control system provides a feedback,
feedforward and/or predictive control of various systems,
processes, inputs and/or outputs related to the conversion of
carbonaceous feedstock into a gas, so to promote an efficiency of
one or more processes implemented in relation thereto. For
instance, various process characteristics may be evaluated and
controllably adjusted to influence these processes, which may
include, but are not limited to, the heating value and/or
composition of the feedstock, the characteristics of the product
gas (e.g. heating value, temperature, pressure, flow, composition,
carbon content, etc.), the degree of variation allowed for such
characteristics, and the cost of the inputs versus the value of the
outputs. Continuous and/or real-time adjustments to various control
parameters, which may include, but are not limited to, heat source
power, additive feed rate(s) (e.g. oxygen, oxidants, steam, etc.),
feedstock feed rate(s) (e.g. one or more distinct and/or mixed
feeds), gas and/or system pressure/flow regulators (e.g. blowers,
relief and/or control valves, flares, etc.), material displacement
within the gasifier (e.g. between vertically successive processing
regions), and the like, can be executed in a manner whereby one or
more process-related characteristics are assessed and optimized
according to design and/or downstream specifications.
[0164] Alternatively, or in addition thereto, the control system
may be configured to monitor operation of the various components of
a given system for assuring proper operation, and optionally, for
ensuring that the process(es) implemented thereby are within
regulatory standards, when such standards apply.
[0165] In accordance with one embodiment, the control system may
further be used in monitoring and controlling the total energetic
impact of a given system. For instance, a given system may be
operated such that an energetic impact thereof is reduced, or again
minimized, for example, by optimising one or more of the processes
implemented thereby, or again by increasing the recuperation of
energy (e.g. waste heat) generated by these processes.
Alternatively, or in addition thereto, the control system may be
configured to adjust a composition and/or other characteristics
(e.g. temperature, pressure, flow, etc.) of a product gas generated
via the controlled process(es) such that such characteristics are
not only suitable for downstream use, but also substantially
optimised for efficient and/or optimal use. For example, in an
embodiment where the product gas is used for driving a gas engine
of a given type for the production of electricity, the
characteristics of the product gas may be adjusted such that these
characteristics are best matched to optimal input characteristics
for such engines.
[0166] In one embodiment, the control system may be configured to
adjust a given process such that limitations or performance
guidelines with regards to reactant and/or product residence times
in various components, or with respect to various processes of the
overall process are met and/or optimised for. For example, an
upstream process rate may be controlled so to substantially match
one or more subsequent downstream processes. Namely, the residence
time of the material within the gasifier, and/or processing regions
thereof, may be set and/or dynamically adjusted by a material
displacement control module, which may operate independently,
cooperatively and/or as a submodule of an overall or global control
system, to meet certain preferences and/or requirements of
downstream processes and/or applications.
[0167] The control system can be adapted for maintaining conditions
suitable for local and/or downstream needs, e.g., temperature,
feedstock input rate, displacement of material, etc. can be
controlled to meet local needs, such as fast processing of waste,
and/or to meet downstream needs such as suitable gas
composition.
[0168] In addition, the control system may, in various embodiments,
be adapted for the sequential and/or simultaneous control of
various aspects of a given process in a continuous and/or real time
manner
[0169] In general, the control system may comprise any type of
control system architecture suitable for the application at hand.
For example, the control system may comprise a substantially
centralized control system, a distributed control system, or a
combination thereof. A centralized control system will generally
comprise a central controller configured to communicate with
various local and/or remote sensing devices and response elements
configured to respectively sense various characteristics relevant
to the controlled process, and respond thereto via one or more
controllable process devices adapted to directly or indirectly
affect the controlled process. Using a centralized architecture,
most computations are implemented centrally via a centralized
processor or processors, such that most of the necessary hardware
and/or software for implementing control of the process is located
in a same location.
[0170] A distributed control system will generally comprise two or
more distributed controllers which may each communicate with
respective sensing and response elements for monitoring local
and/or regional characteristics, and respond thereto via local
and/or regional process devices configured to affect a local
process or sub-process. Communication may also take place between
distributed controllers via various network configurations, wherein
a characteristics sensed via a first controller may be communicated
to a second controller for response thereat, wherein such distal
response may have an impact on the characteristic sensed at the
first location. For example, a characteristic of a downstream
product gas may be sensed by a downstream monitoring device, and
adjusted by adjusting a control parameter associated with the
converter that is controlled by an upstream controller. In a
distributed architecture, control hardware and/or software is also
distributed between controllers, wherein a same but modularly
configured control scheme may be implemented on each controller, or
various cooperative modular control schemes may be implemented on
respective controllers.
[0171] Alternatively, the control system may be subdivided into
separate yet communicatively linked local, regional and/or global
control subsystems. Such an architecture could allow a given
process, or series of interrelated processes to take place and be
controlled locally with minimal interaction with other local
control subsystems. A global master control system could then
communicate with each respective local control subsystems to direct
necessary adjustments to local processes for a global result.
[0172] The control system of the present invention may use any of
the above architectures, or any other architecture commonly known
in the art, which are considered to be within the general scope and
nature of the present disclosure. For instance, processes
controlled and implemented within the context of the invention may
be controlled in a dedicated local environment, with optional
external communication to any central and/or remote control system
used for related upstream or downstream processes, when applicable.
Alternatively, the control system may comprise a sub-component of a
regional and/or global control system designed to cooperatively
control a regional and/or global process. For instance, a modular
control system may be designed such that control modules
interactively control various sub-components of a system, while
providing for inter-modular communications as needed for regional
and/or global control.
[0173] The control system generally comprises one or more central,
networked and/or distributed processors, one or more inputs for
receiving current sensed characteristics from the various sensing
elements, and one or more outputs for communicating new or updated
control parameters to the various response elements. The one or
more computing platforms of the control system may also comprise
one or more local and/or remote computer readable media (e.g. ROM,
RAM, removable media, local and/or network access media, etc.) for
storing therein various predetermined and/or readjusted control
parameters, set or preferred system and process characteristic
operating ranges, system monitoring and control software,
operational data, and the like. Optionally, the computing platforms
may also have access, either directly or via various data storage
devices, to process simulation data and/or system parameter
optimization and modeling means. Also, the computing platforms may
be equipped with one or more optional graphical user interfaces and
input peripherals for providing managerial access to the control
system (system upgrades, maintenance, modification, adaptation to
new system modules and/or equipment, etc.), as well as various
optional output peripherals for communicating data and information
with external sources (e.g. modem, network connection, printer,
etc.).
[0174] The processing system and any one of the sub-processing
systems can comprise exclusively hardware or any combination of
hardware and software. Any of the sub-processing systems can
comprise any combination of none or more proportional (P), integral
(I) or differential (D) controllers, for example, a P-controller,
an I-controller, a PI-controller, a PD controller, a PID controller
etc. It will be apparent to a person skilled in the art that the
ideal choice of combinations of P, I, and D controllers depends on
the dynamics and delay time of the part of the reaction process of
the gasification system and the range of operating conditions that
the combination is intended to control, and the dynamics and delay
time of the combination controller. It will be apparent to a person
skilled in the art that these combinations can be implemented in an
analog hardwired form which can continuously monitor, via sensing
elements, the value of a characteristic and compare it with a
specified value to influence a respective control element to make
an adequate adjustment, via response elements, to reduce the
difference between the observed and the specified value. It will
further be apparent to a person skilled in the art that the
combinations can be implemented in a mixed digital hardware
software environment. Relevant effects of the additionally
discretionary sampling, data acquisition, and digital processing
are well known to a person skilled in the art. P, I, D combination
control can be implemented in feed forward and feedback control
schemes.
[0175] In corrective, or feedback, control the value of a control
parameter or control variable, monitored via an appropriate sensing
element, is compared to a specified value or range. A control
signal is determined based on the deviation between the two values
and provided to a control element in order to reduce the deviation.
It will be appreciated that a conventional feedback or responsive
control system may further be adapted to comprise an adaptive
and/or predictive component, wherein response to a given condition
may be tailored in accordance with modeled and/or previously
monitored reactions to provide a reactive response to a sensed
characteristic while limiting potential overshoots in compensatory
action. For instance, acquired and/or historical data provided for
a given system configuration may be used cooperatively to adjust a
response to a system and/or process characteristic being sensed to
be within a given range from an optimal value for which previous
responses have been monitored and adjusted to provide a desired
result. Such adaptive and/or predictive control schemes are well
known in the art, and as such, are not considered to depart from
the general scope and nature of the present disclosure.
[0176] Sensing elements contemplated within the present context, as
defined and described above, can include, but are not limited to,
temperature sensing elements, position sensors, proximity sensors,
pile height sensors and means for monitoring gas.
[0177] In one embodiment, the gasifier comprises a temperature
sensor array of one or more removable thermocouples. The
thermocouples can be strategically placed to monitor temperature at
various points within each processing region of the gasifier.
[0178] Appropriate thermocouples are known in the art and include
bare wire thermocouples, surface probes, thermocouple probes
including grounded thermocouples, ungrounded thermocouples and
exposed thermocouples or combinations thereof.
[0179] In one embodiment of the invention, individual thermocouples
are inserted into the chamber via a sealed end tube (thermowell)
which is then sealed to the vessel shell, allowing for the use of
flexible wire thermocouples which are procured to be longer than
the sealing tube so that the junction (the temperature sensing
point) of the thermocouple is pressed against the end of the sealed
tube to assure accurate and quick response to temperature change.
Optionally, to prevent material from getting blocked by the
thermocouple tube the end of the sealed tube cap can be fitted with
a deflector. In one embodiment, the deflector is a square flat
plate, with bent corners that contact the refractory and are
in-line with reactant material flow to slip-stream particles over
the thermowell.
[0180] In addition, the invention may comprise devices for
monitoring the exit of product gas. These may include but are not
limited to gas composition monitors and gas flow meters. For
example, as depicted in FIG. 30, a gas analyser is provided
downstream from the gasifier enabling analysis of the product gas,
in this embodiment before homogenization for downstream use, in
order to regulate various aspects of the gasification process. For
example, when it is determined that the carbon content of the
product gas is insufficient, an increase in the high carbon fee
rate (e.g. plastics in feedstock input), when available, is
increased accordingly. In another example, when the heating value
of the product gas (e.g. high heating value, low heating value) is
determined to be too low, the feed rate and additive input ratio
may be adjusted, or again, the high carbon feed rate to MSW feed
rate adjusted.
[0181] Similarly, a gas flow or pressure monitor may be used in an
embodiment where a selected downstream application is adversely
affected by variations and/or absolute fluctuations in gas
flow/pressure. In response to a sensed variation in product gas
pressure, for example, additive input feed rates may be adjusted,
thereby adjusting the gas output of the gasifier. In response to
such adjustment, other process characteristics, such as feedstock
input rate, HCF input rate, process temperature, etc. may also be
adjusted to rebalance the process and substantially maintain
desired output characteristics.
[0182] Furthermore, by measuring process temperatures throughout
the material pile, gas phase temperatures above the pile, and by
measuring resultant off-gas flowrate and analyzing off-gas
composition, the amount of air injected can be optimized to
maximize efficiency and minimize undesirable process
characteristics and products including slagging of ash, combustion,
poor off-gas heating value, excessive particulate matter and
dioxin/furan formation thereby meeting or bettering local emission
standards. Such measurements can be taken during initial start-up
or initial testing of the gasifier, periodically or continually
during operation of the gasifier and may optionally be taken in
real time.
[0183] In one embodiment of the invention, the gasifier can
optionally comprise a pressure sensor or monitor within the
gasifier.
[0184] The gasifier can further comprise level switches or monitors
to assess pile height. Appropriate level switches, sensors and
monitors are known in the art. In one embodiment of the invention,
the level instrumentation comprises point-source level switches. In
one embodiment of the invention, the level switches are microwave
devices with an emitter on one side of the processing chamber and a
receiver on the other side, which detects either presence or
absence of solid material at that point inside the processing
chamber.
[0185] A worker skilled in the art would readily be able to
determine the appropriate placement of level switches, sensors and
monitors such that the desired reactant material pile profile can
be obtained. In one embodiment, the gasifier further comprises
proximity or position sensors.
[0186] Response elements contemplated within the present context,
as defined and described above, can include, but are not limited
to, various control elements operatively coupled to process-related
devices configured to affect a given process by adjustment of a
given control parameter related thereto. For instance, process
devices operable within the present context via one or more
response elements, may include, but are not limited to elements
controlling chamber heating, elements controlling the input of
additives, feedstocks and other process constituents, and elements
of the material displacement control module, to name a few.
[0187] The material displacement control module may be used in such
embodiments to regulate the pile height inside a given chamber of
the gasifier. Low levels of the feedstock pile can result in
fluidization of the reactant material from injection of pre-heated
air while high levels of the feedstock pile can result in poor
temperature distribution through the reactant material pile due to
restricted airflow. Therefore, a level control system with the use
of a series of level switches may be used to maintain stable pile
height inside the gasifier. Maintaining stable level also maintains
consistent residence time in the gasifier.
[0188] The material displacement control module may be used as
necessary to ensure that pile height is controlled at the desired
level. To accomplish this in embodiments in which the material
displacement control module comprise pusher rams, the pusher rams
move in a series of programmed step of which there may exist a
number of control parameters that may include, but are not limited
to: specific movement sequence, speed, distance, and sequence
frequency.
[0189] In some embodiments, the pusher rams move out to a set point
distance, or until a controlling level switch is tripped; either at
the same time or in a pre-determined sequence. The level switch
control action can be based on a single switch, tripping either
empty or full, or may require multiple switches tripping, empty or
full, or any combination thereof. Afterwards, the pusher rams move
back to end the cycle, and the process is repeated. There is an
optional delay between cycles as required by the process and
residence time requirements of the gasifier.
[0190] In one embodiment of the invention where the material
displacement control module comprises an array of pusher rams in
each processing chamber, the height of the reactant material pile
in the processing chamber is a function of the input feed-rate and
the pusher ram motion. Optionally, one processing chamber has three
processing regions and the material displacement control module has
three pusher rams with one pusher ram dedicated to each of the
three processing regions for the movement of reactant
material/residue out of that processing region. The third pusher
ram controlling the movement of the residue out of the third
processing region of the processing chamber sets the throughput by
moving at a fixed stroke length and frequency to discharge the
residue out of the processing chamber. The second pusher ram
follows and moves as far as necessary to push reactant material
onto the third processing region and change the third processing
region's start-of-stage level switch state to "full". The first
pusher ram follows and moves as far as necessary to push reactant
material onto the second processing region and change the second
processing region's start-of-stage level switch state to "full".
All three pusher rams are then withdrawn simultaneously, and a
scheduled delay is executed before the entire sequence is repeated.
Additional configuration may be used to limit the change in
consecutive stroke lengths to less than that called for by the
level switches to avoid excess ram-induced disturbances. The pusher
rams will always need to be moved fairly frequently in order to
prevent over-temperature conditions at the bottom of the processing
chamber.
[0191] A worker skilled in the art will readily understand that the
same pusher ram sequence mentioned above is applicable also when
the three processing regions are distributed across three
processing chambers with one pusher ram per processing region.
Appropriate pusher ram sequences can be readily developed for
different embodiments of the gasifier and are considered to be
within the scope of this invention.
[0192] As with controlled pusher ram sequences between processing
regions and/or chambers, different material movement units (e.g.
mechanisms, devices, etc.) may also be used in a given sequence
and/or according to control parameters of the material movement
control module at least partially influenced by pile height
readings. For example, rotary arm configurations controlling
movement of material between distinct chambers may be used in step
to adjust pile heights within respective processing regions, as can
others of the above examples, as will be apparent to the person of
skill in the art. The control system may be further configured to
assess optimal processing characteristics, taking into account
optimal residence times of material within each region, pile height
restrictions and favourable conditions, as well as other
characteristics as described herein for a given process result.
[0193] Optionally, the control system may further provide for the
control of temperature within the gasifier. For example, to promote
optimisation of the conversion efficiency, the feedstock should be
kept at as high a temperature as possible, for as long as possible.
However, at very high temperatures, the material begins to melt and
agglomerate forming `clinkers` which affects the gasification
performance in multiple ways: (1) it reduces the available surface
area and hence the conversion efficiency; (2) it causes the airflow
in the reactant material pile to divert around the chunks of
agglomeration, aggravating the temperature issues and further
accelerating the agglomeration process; (3) it interferes with the
normal operation of the material displacement control module; and
(4) it can jam the residue removal mechanisms thus potentially
causing a system shut down.
[0194] In order to get the best possible conversion efficiency, the
temperatures in the gasifier and temperature distribution through
the pile can be stabilized and controlled. Stable temperature
distribution throughout the reactant material pile may also be used
to prevent a second kind of agglomeration, in which plastic melts
and acts as a binder for the rest of the reactant material.
[0195] In one embodiment, temperature control within the pile is
achieved by changing the flow of process air into a given region
(ie. more or less combustion). For example, the process air flow
provided to each processing region in the gasifier may be adjusted
by the control system to stabilize temperatures at that region.
Temperature control utilizing displacement units may also be used
to break up hot spots and to avoid bridging.
[0196] In one embodiment, the air flow at each processing region is
pre-set to maintain substantially constant temperature ranges and
ratios between processing regions. Alternatively, air input ratios
may be varied dynamically to adjust temperatures and processes
occurring within each processing region of the gasifier and/or
within the GRS.
[0197] The means for controlling the reaction conditions to manage
the chemistry and energetics of the gasification of a feedstock
comprise a main integrated processor and a series of sensors for
monitoring the state of the system and control systems for
controlling various operational parameters, for example, the rate
of addition of feedstock and/or additives, as well as operating
conditions, such as pressure in the processing chamber. The main
integrated processor receives data obtained from sensors relating
to current states of the gasification reaction, and processes these
data to generate an appropriate set of output instructions to
manage the chemistry and energetics of the conversion reaction,
whereby the optimal reaction set point is maintained.
[0198] In response to the information input, the conditions within
the gasifier can be adjusted either manually or automatically. The
gasifier can be regulated by a series of on/off switches and
instruments. The computation means can optionally include various
output means. Different types of control schemes, outlined below,
can be used.
[0199] a) Fuzzy Logic Control and Other Types of Control:
[0200] Fuzzy logic control as well as other types of control can
equally be used in feed forward and feedback control schemes. These
types of control can substantially deviate from classical P, I, D
combination control in the ways the reaction dynamics are modeled
and simulated to predict how to change input variables or input
parameters to affect a desired outcome. Fuzzy logic control usually
only requires a vague or empirical description of the reaction
dynamics (in general the system dynamics) or the operating
conditions of the system. Aspects and implementation considerations
of fuzzy logic and other types of control are well known to a
person skilled in the art.
[0201] b) Feed-Forward Control:
[0202] Feed forward control processes input parameters to
influence, without monitoring, control variables and control
parameters. A gasification facility can use feed forward control
for a number of control parameters such as the amount of power
supplied to one of the one or more plasma torches in the gas
reformulating chamber (GRS). The power output of the arcs of plasma
torches can be controlled in a variety of different ways, for
example, by pulse modulating the electrical current which is
supplied to the torch to maintain the arc, varying the distance
between the electrodes, limiting the torch current, or affecting
the composition, orientation or position of the plasma.
[0203] The rate of supply of additives to the gasifiers and/or the
gas reformulator in a gaseous or liquid form or a pulverized form
which can be sprayed or otherwise injected via nozzles, can be
controlled with certain control elements in a feed forward way.
Effective control of an additive's temperature or pressure,
however, may require monitoring and closed loop feed back
control.
[0204] c) Feed-Back Control:
[0205] In feedback control the value of a control parameter or
control variable is compared to a desired value. A control signal
is determined based on the deviation between the two values and
provided to a control element in order to reduce the deviation. For
example, when the output gas exceeds a predetermined H.sub.2:CO
ratio, a feedback control system can determine an appropriate
adjustment to one of the input variables, such as increasing the
amount of additive air to return the H.sub.2:CO ratio to the
desired value. The delay time to affect a change to a control
parameter or control variable is sometime called loop time. The
loop time, for example, to adjust the power of the plasma arc, air
or steam flow rate, can amount to 30 to 60 seconds.
[0206] Feed back control may be used for all control variables and
control parameters which use direct monitoring or where a model
prediction is satisfactory. There are a number of control variables
and control parameters of the gasifier that lend themselves towards
use in a feedback control scheme. Feedback schemes can be
effectively implemented in aspects of the control system for those
control variables or control parameters which can be directly
sensed and controlled and whose control does not, for practical
purposes, depend upon other control variables or control
parameters.
Modularity of the System
[0207] Modulated plants are facilities where each function block is
pre-built components. This allows for the components to be built in
a factory setting and then sent out to the facility site. These
components (or modules) include all the equipment and controls to
be functional and are tested before leaving the factory. Modules
are often built with a steel frame and generally incorporate a
variety of possible sections, such as: Gasifier Block, Gas
Conditioning System Block, Power Block, etc. Once on-site, these
modules would only need to be connected to other modules and the
control system to be ready for plant's commissioning. This design
allows for shorter construction time and economic savings due to
reduced on-site construction costs.
[0208] There are different types of modular plants set-ups. Larger
modular plants incorporate a `backbone` piping design where most of
the piping is bundled together to allow for smaller footprint.
Modules can also be placed in series or parallel in an operation
standpoint. Here similar tasked equipment can share the load or
successively provide processing to the product stream.
[0209] One possible application of modular design in this
technology is it allows more options in the gasification of
multiple wastes. This technology can allow for multiple gasifiers
to be used in a single high-capacity facility. This would allow the
option of having each gasifier co-process wastes together or
separately; the configuration can be optimized depending on the
wastes.
[0210] If an expansion is required due to increasing loads, a
modular design allows this technology to replace or add modules to
the plant to increase its capacity, rather then building a second
plant. Modules and modular plants can be relocated to other sites
where they can be quickly integrated into a new location.
Function Block Combination
[0211] It is possible to combine the functions of different
gasification trains (series of equipment) so that common functions
can be carried out in function blocks that take in gases or
material from more than one stream. The following diagrams
demonstrate this concept as applied to carbonaceous feedstock
gasification.
[0212] In these embodiments there are two trains shown although
this set-up of combined functions between trains can occur for any
number of trains and for any feedstock per train (even if one train
has a combined feedstock). Once a stream has been combined one may
still choose parallel handling equipment downstream; the parallel
streams do not need to be of the same size even if handling the
same gases.
[0213] For the following description, GCS refers to the gas
conditioning system mentioned above and the numbers represent the
following systems [0214] 1. Gasifier [0215] 2. Residue Conditioning
System [0216] 3. Gas Reformulating System
[0217] None Combined, FIG. 31 [0218] In this embodiment there are
two separate systems that can have the gas streams mixed for
downstream system; like the homogenization tank or engines.
[0219] GCS Combined [0220] In this embodiment the gases from
function blocks 2 & 3 from each train are fed together into a
single GCS which has been sized appropriately for the gas flow.
[0221] Function 2 Combined, FIG. 32 [0222] In this embodiment the
trains differ only in function block 1, with all other functions
being handled by the same combined train of equipment.
[0223] Function 3 Combined, FIG. 33 [0224] In this embodiment gases
from function blocks 1 go to a combined function block 3; which is
sized appropriately.
[0225] Function 2 & 3 Combined, FIG. 34 [0226] In this
embodiment gases from function blocks 1 go to a combined 2 and
material from function block 1 go to a combined function block 3;
which are sized appropriately. Gases from combined function blocks
2 & 3 then travel to a combined GCS.
[0227] A worker skilled in the art will readily understand that
while in the above section we have mentioned the gasification
system as comprising of the function blocks 1, 2 & 3 and the
GCS, it can be further subdivided into other smaller function
blocks. For example, the function block 1, 2 & 3 could
represent the drying region, volatilization region and the carbon
conversion region respectively such that a single gasifier can be
formed by the combination of these function blocks. A worker
skilled in the art will readily appreciate that for each
designation of function blocks, the trains can be combined in a
larger family of schemes depending on where the combination of the
trains is effected.
[0228] The embodiments of the invention being thus described, it
will be obvious that the same may be varied in many ways. Such
variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be
obvious to one skilled in the art are intended to be included
within the scope of the following claims.
* * * * *