U.S. patent application number 14/233460 was filed with the patent office on 2014-09-25 for waste processing.
This patent application is currently assigned to Chinook End-Stage Recycling Limited. The applicant listed for this patent is Rifat Al Chalabi, Ophneil Henry Perry, John Turner. Invention is credited to Rifat Al Chalabi, Ophneil Henry Perry, John Turner.
Application Number | 20140284197 14/233460 |
Document ID | / |
Family ID | 44586911 |
Filed Date | 2014-09-25 |
United States Patent
Application |
20140284197 |
Kind Code |
A1 |
Chalabi; Rifat Al ; et
al. |
September 25, 2014 |
Waste Processing
Abstract
M&C PB 143543WO 22 31524653-1-abhimani ABSTRACT An apparatus
and method for processing organic materials is provided comprising
an elongate process tube (22) having an inlet for receiving the
material and an outlet for processed material. A gas conveying
system fluidically conveys the material through the processing
tube, The gas conveying system comprises a supply of conveying gas
which is a hot pressurised inert gas, connected to the processing
tube (22) at its inlet end. A control system is configured to
control the supply of the pressurised inert gas to the processing
tube (22) so as to convey a batch of material through the tube (22)
whilst simultaneously heating said it to cause the organic matter
therein to gasify to produce process. The processing tube (22) has
a plurality of sections, each separated by a closure (44), and the
gas conveying means conveys the material from one section to the
next.
Inventors: |
Chalabi; Rifat Al;
(Nottingham, GB) ; Perry; Ophneil Henry;
(Nottingham, GB) ; Turner; John; (Nottingham,
GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chalabi; Rifat Al
Perry; Ophneil Henry
Turner; John |
Nottingham
Nottingham
Nottingham |
|
GB
GB
GB |
|
|
Assignee: |
Chinook End-Stage Recycling
Limited
Nottingham
GB
|
Family ID: |
44586911 |
Appl. No.: |
14/233460 |
Filed: |
July 12, 2012 |
PCT Filed: |
July 12, 2012 |
PCT NO: |
PCT/GB2012/051648 |
371 Date: |
April 16, 2014 |
Current U.S.
Class: |
201/1 ; 201/29;
201/36; 202/99 |
Current CPC
Class: |
C10J 3/14 20130101; C10B
49/08 20130101; C10J 3/002 20130101; C10J 2300/1253 20130101 |
Class at
Publication: |
201/1 ; 201/29;
202/99; 201/36 |
International
Class: |
C10B 49/08 20060101
C10B049/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 20, 2011 |
GB |
1112503.6 |
Claims
1. Apparatus for processing material such as organically coated
waste and organic materials including biomass, industrial waste,
municipal solid waste and sludge; the apparatus comprising: an
elongate process tube having an inlet for receiving the material
and an outlet for processed material; a gas conveying system for
fluidically conveying said material through said processing tube,
said conveying system comprising a supply of conveying gas,
comprising hot pressurised inert gas, connected to said processing
tube at its inlet end; and a control system configured to control
the supply of said pressurised inert gas to said processing tube so
as to convey a batch of said material through said tube
simultaneously heating said material to cause any organic matter
therein to gasify to produce process gas wherein the processing
tube comprises a plurality of sections, each separated by a valve,
and wherein the gas conveying system is configured to convey the
material from one section to the next.
2. The apparatus of claim 1 further comprising a separator
configured to extract the process gas from the processing tube.
3. The apparatus of claim 1 wherein the gas conveying system
includes a conveying gas inlet associated with each section for the
supply of conveying gas to move the material therein into the next
section.
4. The apparatus of claim 1 further comprising a conveying gas
compressor for increasing the pressure of the conveying gas and
wherein expansion of the conveying gas moves the material in the
processing tube.
5. The apparatus of claim 4 wherein the conveying gas compressor
comprises a compression chamber having a piston therein for
receiving said conveying gas and an actuator for moving said piston
in said chamber to compress the gas therein.
6. The apparatus of claim 5 wherein the compression chamber is
sized such that one stroke of the piston in the chamber expels
sufficient conveying gas to convey material from one section of the
processing tube to be to another.
7. The apparatus of claim 4 wherein each section of the processing
tube has a compressor associated with it.
8. The apparatus of claim 1 further comprising a fluid outlet in
each section of the tube for draining fluid therefrom.
9. The apparatus of claim 5 further comprising a fluid outlet in
each section of the tube for draining fluid therefrom and a fluid
inlet in the conveying gas inlet conduit of each section for
feeding fluid into said conveying gas.
10. The apparatus of claim 1 further comprising at least one
thermal treatment chamber for thermally treating the process gas
produced by the apparatus by heating it so as to breakdown any
volatile organic compounds therein.
11. The apparatus of claim 10 further comprising an outlet conduit
from at least one thermal treatment chamber for supplying hot
process gas therefrom to the processing tube for use as said
conveying gas.
12. The apparatus of claim 1 further comprising: a feed hopper for
receiving and temporarily storing material to be processed, and a
secondary hopper fed by the feed hopper wherein the secondary
hopper is connected to the processing tube by a valve and wherein
the secondary hopper has a conveying gas inlet at an upper end
thereof.
13. The apparatus of claim 1 wherein each section of the processing
tube has a process gas outlet towards its downstream end.
14. The apparatus of claim 1 further comprising sensors to sense
the quality of the process gas and: if it does not meet a
predetermined criteria, recirculating the process gas through the
processing tube and, if it does meet the predetermined criteria
extracting at least a part of the process gasses for storage or
direct use.
15. The apparatus of claim 1 wherein the interior surface of the
processing tube is provided with fixed agitators to promote the
tumbling of material within said tube as it is conveyed
therethrough.
16. A method for processing material such as organically coated
waste and organic materials including biomass, industrial waste,
municipal solid waste and sludge; the method comprising: providing
an elongate process tube having an inlet for receiving the material
and an outlet for processed material; providing a gas conveying
system for fluidically conveying said material through said
processing tube, said conveying system comprising a supply of hot
pressurised inert gas connected to said processing tube at its
inlet end; and controlling the supply of said pressurised inert gas
to said processing tube so as to convey a batch of said material
through said tube thereby heating said material to cause any
organic matter therein to gasify to produce process gas wherein the
processing tube comprises a plurality of sections, each separated
by a valve, each section having a conveying gas inlet associated
therewith for the supply of conveying gas; the method further
comprising controlling the supply of conveying gas so as to convey
the material from one section to the next.
17. The method of claim 16 further comprising separating the
process gas from the processing tube.
18. The method of claim 17 further comprising compressing the
conveying gas to increase its pressure and wherein expansion of the
conveying gas moves the material in the processing tube.
19. The method of claims 16 further comprising draining fluid from
each section of the tube via a fluid outlet therein.
20. The method of claim 19 further comprising supplying fluid
drained from the tube into the conveying gas upstream of the
processing tube.
21. The method of claim 20 wherein the temperature of the conveying
gas is sufficient to vaporise the fluid added thereto, thereby
increasing the pressure of said conveying gas.
22. The method of claims 16 further comprising heating the process
gases in a thermal treatment chamber to thermally breakdown any
volatile organic compounds therein.
23. The method of claim 22 further comprising supplying hot process
gas from the thermal treatment chamber to the processing tube for
use as said conveying gas.
24. The method of claims 16 further comprising: providing a feed
hopper for receiving and temporarily storing material to be
processed; providing a secondary hopper fed by the feed hopper
wherein the secondary hopper is connected to the processing tube by
a valve; providing a conveying gas inlet at an upper end of the
secondary hopper; feeding a batch of material to be processed from
the feed hopper to the secondary hopper; passing gas through the
conveying gas inlet and opening the valve such that the batch of
material is conveyed from the secondary hopper into the processing
tube.
25. The method of claims 16 further comprising providing each
section of the processing tube with a process gas outlet towards
its downstream end and extracting process gas via said process gas
outlets.
26. The method of claims 16 further comprising sensing the quality
of the process gas and: if it does not meet a predetermined
criteria, recirculating the process gas through the processing tube
and, if it does meet the predetermined criteria extracting at least
a part of the process gasses for storage or direct use.
27. The method of claims 16 further comprising providing a waste
material silo downstream of the processing tube for collecting the
inert fully processed material.
28. The method of claims 16 further comprising agitating said
material within the tube as it is conveyed there through.
29. The method of claim 16 further comprising heating the process
gases from initial sections of the processing tube in a first
thermal treatment chamber, to thermally breakdown any volatile
organic compounds therein, and recycling the treated gas as
conveying gas.
30. The method of claim 29 further comprising heating the process
gases from final sections of the processing tube in a second
thermal treatment chamber, to thermally breakdown any volatile
organic compounds therein.
31. The method of claim 16 further comprising determining the
quality of the process gas and: if the process gas is below a
predetermined quality threshold, passing the process gas through a
first thermal treatment chamber to heat the gas so as to thermally
breakdown any volatile organic compounds therein, and recycling the
treated gas as conveying gas; and if the process gas is above a
predetermined quality threshold, passing the process gas through a
second thermal treatment chamber to heat the gas so as to thermally
breakdown any volatile organic compounds therein.
Description
[0001] The present invention relates to improvements in the
processing of materials having an organic component. In particular
the method relates to improvements in the processing of such
materials in a semi continuous process.
[0002] The batch processing and the continuous processing of
materials to gasify them or pyrolyse them to produce synthesis gas
is known in the art.
[0003] One known continuous method is the use of conveying ovens,
these systems uses a mesh belt conveyor to transport materials for
treatment through an oven. Hot gasses are passed through the
material on the belt as it passes through the oven. A problem with
this method is that the depth of materials on the belt limits the
process. The materials are stacked which reduces efficiency as the
hot gases do not come in to contact with the materials that are
enclosed within the stack of materials on the mesh. It is
advantageous for efficient processing of the material that all the
surfaces of the materials being treated are exposed to the hot
gases. Also there is no agitation of the material being treated and
conveyor belt life is usually short.
[0004] Another known continuous method is the use of rotating
kilns. In this method a large kiln is inclined to the horizontal so
that material fed or charged into the kiln at its highest end
travels towards the lowest end, where it is discharged, under the
influence of gravity. The kiln is rotated so that material within
the kiln is agitated and a flow of hot gases is provided to heat up
the material as it travels through the kiln. One problem with this
method is that there are a large number of moving parts, in
particular the fact that the whole kiln rotates is a source of
constant wear and possible failure, especially in relation to the
rotating seals at either end which much seal across a wide range of
temperatures. A further problem is that these ovens commonly take
up a large amount of space in comparison to their throughput of
material.
[0005] It is a further problem with continuous processes that their
processing parameters are usually set to a very stable level so
that the material passing therethrough can be guaranteed to be
fully processed. This can create problems if there are large
variations in the material that is required to be processed, for
example the water content.
[0006] Entrained flow furnaces in which small particles of organic
matter are entrained in a hot gas flow which is passed through a
furnace are known, for example from Japanese patent application
JP2009256490.
[0007] It is also known to dry waste, or example municipal waste by
heating it by passing a flow of ht gas over or through it. Examples
of such prior art is disclosed in Japanese patent application
JP9042836, in PCT publication WO2010/027138, and European
application EP0031939.
[0008] It is the purpose of the present invention to provide an
improved method and apparatus for processing material having an
organic component.
[0009] According to a first aspect of the invention there is
provided an apparatus for processing material such as organically
coated waste and organic materials including biomass, industrial
waste, municipal solid waste and sludge; the apparatus comprising:
an elongate process tube having an inlet for receiving the material
and an outlet for processed material; a gas conveying system for
fluidically conveying said material through said processing tube,
said conveying system comprising a supply of conveying gas,
comprising hot pressurised inert gas, connected to said processing
tube at its inlet end; and a control system configured to control
the supply of said pressurised inert gas to said processing tube so
as to convey a batch of said material through said tube
simultaneously heating said material to cause any organic matter
therein to gasify to produce process gas, wherein the processing
tube comprises a plurality of sections, each separated by a
closure, and the gas conveying means is configured to convey the
material from one section to the next.
[0010] By processing in this manner essentially a continuous batch
process is affected. This gives the flexibility of modifying
processing parameters associated with batch processing together
with the benefits of continuous process, e.g. better throughput of
material, no interbatch downtime etc.
[0011] Preferably the apparatus further comprises separation means
for extracting the process gas from the processing tube.
[0012] Preferably the gas conveying means includes a conveying gas
inlet associated with each section for the supply of conveying gas
to move the material therein into the next section. Preferably each
section of the processing tube has a process gas outlet towards its
downstream end.
[0013] By breaking the process down into sections of tube the
parameters for each section can be independently monitored, e.g.
fluid extraction/addition (see below). Furthermore as hot conveying
gas is introduced at each stage the greater the number of sections
the greater the heat input from the conveying gas.
[0014] The apparatus may comprise a conveying gas compressor for
increasing the pressure of the conveying gas and expansion of the
conveying gas moves the material in the processing tube.
[0015] The conveying gas compressor may comprise a compression
chamber having a piston therein for receiving said conveying gas
and an actuator for moving said piston in said chamber to compress
the gas therein. Preferably the compression chamber is sized such
that one stroke of the piston in the chamber expels sufficient
conveying gas to convey material from one section of the processing
tube to another.
[0016] In one preferred arrangement each section of the processing
tube has a compressor associated with it. In an alternative
arrangement the apparatus may be provided with one central
compressor and the gas may be directed to the required sections of
the processing tube by valve means.
[0017] The apparatus may comprise a fluid outlet in each section of
the tube for draining fluid therefrom. The apparatus may also
include a fluid inlet in the conveying gas inlet conduit of each
section for feeding the drained fluid into said conveying gas. As
the hot conveying gas is at an elevated temperature, in the region
of several hundreds of degrees, the fluid will vaporise when it is
added to the conveying gas, the expansion in volume as it vaporises
will slightly drop the temperature of the gas but will boost its
pressure, thereby assisting in conveying the material along the
tube.
[0018] In a preferred arrangement the apparatus further comprises a
thermal treatment chamber for thermally treating the process gas
produced by the apparatus by heating it so as to breakdown any
volatile organic compounds therein. Preferably an outlet conduit is
provided from the thermal treatment chamber for supplying hot
process gas therefrom to the processing tube for use as said
conveying gas.
[0019] The apparatus may comprise: a feed hopper for receiving and
temporarily storing material to be processed, and a secondary
hopper fed by the feed hopper wherein the secondary hopper is
connected to the processing tube by a valve and wherein the
secondary hopper has a conveying gas inlet at an upper end thereof.
In this way batches can continuously be gated through the secondary
hopper, from the first hopper, and introduced into the process.
[0020] The apparatus may be provided with sensors to sense the
quality of the process gas and: if the sensed quality does not meet
a predetermined criteria, the apparatus may be controlled to
re-circulate the process gas through the processing tube as
conveying gas and, if it does meet the predetermined criteria at
least some of the process gas may be extracted for storage or
direct use.
[0021] The interior surface of the processing tube may be provided
with fixed agitators to promote the tumbling of material within
said tube as it is conveyed therethrough.
[0022] According to a second aspect of the invention there is
provided a method for processing material such as organically
coated waste and organic materials including biomass, industrial
waste, municipal solid waste and sludge; the method comprising:
providing an elongate process tube having an inlet for receiving
the material and an outlet for processed material; providing a gas
conveying system for fluidically conveying said material through
said processing tube, said conveying system comprising a supply of
hot pressurised inert gas connected to said processing tube at its
inlet end; and controlling the supply of said pressurised inert gas
to said processing tube so as to convey a batch of said material
through said tube thereby heating said material to cause any
organic matter therein to gasify to produce process gas, the
processing tube further comprising a plurality of sections, each
separated by a closure, each section having a conveying gas inlet
associated therewith for the supply of conveying gas; and wherein
the method further comprises controlling the supply of conveying
gas so as to convey the material from one section to the next.
[0023] Preferably the method further comprises separating the
process gas from the processing tube.
[0024] Preferably the method comprises compressing the conveying
gas to increase its pressure and wherein expansion of the conveying
gas moves the material in the processing tube.
[0025] The method may comprise draining fluid from each section of
the tube via a fluid outlet therein. The fluid drained from the
tube may then be supplied into the conveying gas upstream of the
conveying tube. The temperature of the conveying gas is sufficient
to vaporise the fluid added thereto, thereby increasing the
pressure of said conveying gas.
[0026] The method preferably comprises heating the process gases in
a thermal treatment chamber to thermally breakdown any volatile
organic compounds therein. The hot process gas may then be supplied
from the thermal treatment chamber to the processing tube for use
as said conveying gas.
[0027] In one embodiment the method comprises: providing a feed
hopper for receiving and temporarily storing material to be
processed; providing a secondary hopper fed by the feed hopper
wherein the secondary hopper is connected to the processing tube by
a valve; providing a conveying gas inlet at an upper end of the
secondary hopper; feeding a batch of material to be processed from
the feed hopper to the secondary hopper; passing gas through the
conveying gas inlet and opening the valve such that the batch of
material is conveyed from the secondary hopper into the processing
tube.
[0028] Preferably each section of the processing tube is provided
with a process gas outlet towards its downstream end for the
extraction of the process gas via said process gas outlets.
[0029] The method may include sensing the quality of the process
gas and: if it does not meet a predetermined criteria,
recirculating the process gas through the processing tube and, if
it does meet the predetermined criteria extracting at least a part
of the process gasses for storage or direct use.
[0030] The method may comprise providing a waste material silo
downstream of the processing tube and collecting the inert fully
processed material in the silo.
[0031] The method may comprise agitating the material within the
tube as it is conveyed therethrough.
[0032] Specific embodiments of the invention will now be described
with reference to the drawings in which:
[0033] FIG. 1 is a schematic diagram of a first embodiment of the
invention;
[0034] FIG. 2 is a schematic diagram of a second embodiment of the
invention;
[0035] FIG. 3 is a schematic diagram of the invention;
[0036] FIG. 4 is a partially cut away section of a processing tube
of an alternative embodiment, in accordance with the invention;
[0037] FIG. 5 is a cross section through a processing tube of an
alternative embodiment, in accordance with the invention; and
[0038] FIG. 6 is a schematic diagram of an alternative embodiment
of the invention.
[0039] Referring to FIG. 1 a feed hopper 1 is provided for the
waste material to be loaded, which may be by conventional methods,
for example conveyor, directly from a tipping truck or from a
vehicle with a bucket loading capability.
[0040] The term `waste material` is used throughout the following
description and describes the material which is to be processed by
the apparatus, and can take many different forms. It will be
appreciated by the skilled person that the system could process any
material containing a large percentage of organic matter.
[0041] A valve 3 is provided to allow the waste material 2 to be
introduced into the secondary hopper 4 in a metered amount based on
volume or weight.
[0042] The initial introduction of the waste material into the
process tube can be done using existing pneumatic conveying
methods, which are known in the art, but to describe it briefly,
when valve 3 is opened, valve 8 remains closed and the hopper is
allowed to vent air out of the hopper at a position local to valve
8 and also at the top of the hopper at a position local to valve 3
as the waste material falls through the valve 3 and fills the
secondary hopper, allowing the air to escape.
[0043] A compressed air supply is connected to the secondary hopper
via conduit 10 so as to push the waste material into the process
tube 22 by allowing compressed air to enter at position 10 when
valve 8 is opened and valve 3 is closed. Although this part of the
system charging may be performed using conventional pneumatic means
as described, it will be appreciated that this loading part, may
be, achieved by using the hot process gas as the conveying gas, as
described herein below for the general movement of the waste
material through the system, instead of normal compressed air.
[0044] The basis of operation of this invention is that waste
material is conveyed from entry point to exit point through the
processing tube by the hot gas used in the gasification process
itself. In doing so the gas applies a pressure to the waste
material in order to cause conveying movement and therefore
agitation by default of its movement. In doing so the waste
material in part or bulk is subjected to exposure to the hot
process gas thereby causing its gasification. The gasification
process creates a process gas which contains carbon monoxide (CO)
and hydrogen (H.sub.2), which is commonly referred to as
syngas.
[0045] The waste material is moved through the process apparatus,
not by compressed air in the conventional method, but by a
pressurised supply of hot process gas from the gasification
process.
[0046] Typically at locations along the process tube the hot gas is
entered under pressure from one of a proposed number of compression
chambers 21, each of which is mounted adjacent to a section length
of process tube and is connected to the hot process gas inlet duct
19. The sections are separated by valves 44 into a plurality of
discreet chambers.
[0047] In one of a number of preferred embodiments, typically a
chamber 21 is provided which houses a piston 20 which is movable in
the direction of the arrows 13 and 14 in a working stroke and which
may be actuated by conventional means, for example by connection to
a hydraulic cylinder 15.
[0048] When the piston 20 is actuated to travel in the direction of
arrow 13 the valve 11 and 17 are closed on the chamber 21 whilst
valves 12 and 16 are open thus allowing hot gas 53 from the inlet
duct 18 piped from the larger duct 19 to be compressed under the
movement of the piston 20 to a suitable pressure required to cause
the gas to be forced out through the valve 12 and duct 10 and into
the secondary hopper 4 causing the waste material 2A to have a
pressure applied to it so that it is forced to move through valve 8
and commence the journey through the process tube 22.
[0049] Whilst the piston is moving in the direction of arrow 13,
valve 16 is open and allows the continuous unrestricted flow of hot
gas from the duct 18 to be maintained and thus there is no pressure
drop in the hot gas flow 53 in the duct 19.
[0050] As the secondary hopper fills with waste material 2A then
valve 5 and 7 are open to allow trapped air to escape through duct
6 and join the outlet gas duct 47.
[0051] The valves 5 and 7 are closed prior to the secondary chamber
4 being filled with pressurised hot gas through the duct 10.
[0052] As the volume is filled freely by the gas 53 behind the
piston then at the end of the stroke of the piston 20 the valves 11
and 17 are opened and valves 12 and 16 are closed, allowing the
free space in the chamber to continue to fill with hot inlet gas 53
through valve 17 from duct 18 behind the piston as it moves in the
direction of arrow 14 forcing pressurised hot gas to travel through
the valve 11 and pressurise the next batch of material 2A already
loaded in the secondary hopper 4. In this way both stroke
directions of the piston are utilised.
[0053] The size of the chamber 21 is calculated such that enough
volume of hot gas can be compressed by the piston in a single
stroke, to cause the waste material to be conveyed through the
process tube in a metered increment by effectively pressurising a
slug of waste material in a conventional manner to existing
pneumatic conveying methods. The technique is known widely in the
conveying industry and various terms exist such as dense phase,
lean phase and pulse phase, but the salient point is that the
proposed apparatus uses the process hot gas to convey whilst also
causing gasification. The use of hot gas therefore has a dual
purpose, to move the material in increments through the process
tube 22 and to heat the material so as to cause it to become
gasified.
[0054] The process is incremental and so a number of chambers
typical to the chamber 21 are mounted at appropriate length
intervals adjacent and along the length of the process tube 22 at
suitably timed intervals to create continuous, or semi continuous
conveying of the waste material, for example there may be a
residency time of the material in each section prior to it being
conveyed to the following section.
[0055] Typically as the previous described function is taking place
then the same function is performed by a number of chambers along
the process tube length 22.
[0056] For example, at the same time as the piston 20 moves in the
direction of arrow 13 then the piston 31 is actuated by a suitable
means 32 whilst valves 25 and 24 are closed then valves 23 and 26
remain open whilst the piston 31 moves in the direction of arrow
29. Again hot gas is pressurised in the chamber 30 and forced
through the valve 23 and duct 9 and into the process tube 22 at a
position in front of the previous slug of waste material 2B. As the
piston 31 moves in the direction of arrow 29 the chamber 30
continues to fill as valve 26 is open and hot gas 53 passes
unrestricted from the duct 27.
[0057] Similar to previously described, the piston 31 returns in
the direction as shown by the arrow 28 and valves 23 and 26 closes
whilst valves 25 and 24 open allowing continuation of the process
cycle.
[0058] A valve 44 typically seals each section of process tube 22
along the length and the valves may be selectively operated in
sequence with the chambers to effect the conveying of the material
through the system by gas conveying.
[0059] The process is repeated for as many sections as required and
the waste material is conveyed typically in slugs depicted by 2B,
2C, 2D etc. In operation the operation will typically be sequenced
so that material in a downstream chamber is first conveyed out of
that chamber before the upstream material is conveyed into that
chamber.
[0060] The gas from the process within the process tube 22 is
expelled through valves 45, located in each tube section, and out
through the conduits 46 into the main outlet process gas duct 47
for the gasification process. Some of the process gasses are also
allowed to pass through the end of the process tube and into the
collection silo 48 at the end of the process tube, where it can
escape through valve 51 and duct 52 into the main outlet duct 47. A
valve 50 is provided in the bottom of the silo to enable the inert
processed material to be removed therefrom.
[0061] The process waste 49, which is fully processed and is inert,
is captured from the end of the process tube 22 and collected in
the silo 48 which can be emptied through a valve 50.
[0062] It may be appreciated that the explanation of exact timing
of the chamber actuations and location of hot process gas entry
need not be strictly complied with as depicted in the accompanying
FIG. 1 which is intended to be a schematic representation of the
system.
[0063] Although shown as a continuous straight process tube 22 it
will be appreciated that the process does not have to be a
continuous length but could be a number of stage sections where the
waste material can be traversed to and from one stage section to
the next. Alternatively the process tube 22 can be arranged in a
number of stages in a circular arrangement to allow the waste
material to pass continuously around the loop sections and then
emptied via a suitable exit valve and silo once gasification is
complete, but either of these arrangements would make the process
more akin to a batch system.
[0064] Referring again to the Figures the initial zones of the
process tube 22 may have a facility to allow much higher
compression of the waste material 2C and 2D for example such that
any H.sub.2O or fluid may be squeezed out of the waste material and
drained via the collection point 57 in each of the process tube
sections, stored and subsequently used at any point in the
gasification phase by controlled means. In particular water
extracted in the earlier phases, where there is an excess of
H.sub.2O in the material, a may be reintroduced into the system in
the later stages of the process tube 22 by which stage the majority
of the moisture has been used and there is a shortage of moisture
for the gasification process.
[0065] It may be appreciated that H.sub.2O collected from the
initial compression stages at valves 57 described above, can be
added to the hot gas entry at any of the zones via the inlet valves
56 to cause pressurisation to help with heat transfer and hot gas
(syngas) penetration through the waste material surface in the
process tube. In particular the hot gas will vaporise the water as
it is added and the increased volume of the liquid to gas phase
change will cause a pressure increase in the process gas as it is
added, thereby accelerating the gas into the processing tube 22 and
assisting in conveying the material therein.
[0066] After each section a process check will be made of the
process gas being extracted from that section giving the status of
gas quality (chemical composition and temperature) and if the
overall quality is good then the gas is qualified as process gas,
and is allowed to pass through ducts 46 and into the outlet gas
duct 47, and if the quality is poor then it will need
reconditioning prior to using it in the next zone. In this case the
gas will be re circulated via the exit pipes 54 and entered into
the hot gas inlet ducts 27 via the valves 55 or any other suitable
location. In this manner the process gas being extracted from the
system via the conduit 47 can be controlled so that it is of a high
quality. This ability to recycle the gas in individual sections of
the apparatus gives the flexibility of a batch operating system and
the gas conveying from one section to another gives the benefit of
continuous operation. The apparatus therefore can operate in a
continuous manner but is very adaptable at handling different waste
products having different calorific values and different organic
and moisture contents.
[0067] The pressure and temperature of the hot gas on entry to the
sections via the inlets can be controlled to be higher in the later
zone stages to collect CO and H.sub.2 and break larger hydrocarbon
molecules (CxHy).
[0068] With reference to FIG. 2 the system shown functions in the
same manner as that shown in FIG. 1 except for the variation
described below where a single pressurised tank 61 may be mounted
remote from the process tube 22 above or below ground level. The
tank is pressurised by a single compressor 62 which may be of the
type described with reference to FIG. 1 or may be any other type of
high temperature compressor.
[0069] As described previously, a recirculation loop can be
provided to each section and a process check will be made giving
the status of process gas overall quality and if the overall
quality is good then the process gas passes through ducts 46 and
into the outlet gas duct 47 and if the quality is poor then it can
be re circulated via the exit pipes 54 and entered into the hot gas
inlet duct via the valves 55 or any other more suitable location.
It will be appreciated that in this arrangement the gas that is
re-circulated is re-circulated into all of the sections as opposed
to only the section from which it originated, as with the example
of FIG. 1.
[0070] The process tube 22 also can be situated above or below
ground level typically and if the tube is mounted below ground
level then the compressed hot gas can be stored in a single
pressurised tank 61, above or below ground, to feed all of the
process tube zones, each of which can be selected for actuation in
sequence via the relevant control valves 60. In the example of FIG.
1 if the process tube 22 is situated below ground then the
compressors, which have moving parts and are therefore more likely
to require maintenance, are situated above ground, or at least in
an easily accessible position to facilitate maintenance.
Furthermore the valves 44 that control the movement of waste from
one section to another will each have an actuator to control them
which is likewise also preferably situated above ground or at least
in a readily accessible location.
[0071] Also as described previously it may be appreciated that
H.sub.2O collected from the initial compression stages at valves 57
described previously, can be added to the hot process gas entry at
any of the zones via the inlet valves 56 to cause pressurisation
and to help with heat transfer and hot gas (syngas) penetration
through the waste material surface in the process tube.
[0072] As the waste material reduces in volume as it travels
through the process tube (due to the continuous gasification), the
last section zones can reduce in cross section or the mode of
operation adjusted to give a higher flow to support less mass but
higher density material transportation.
[0073] The movement speed of the waste material as it is conveyed
through the process tube 22 can be proportional to the waste
material requirements to process and gasify the organic matter
therein and can be speeded up or slowed down accordingly by
controlling one or more of, valve timings, compressor actuator
operation and the introduction of H.sub.2O into the process tube
sections.
[0074] Referring now to both embodiments, raised portions of
suitable form and size are mounted inside the process tube 22 along
its length to cause the waste material 2C, 2D etc. to tumble and
reform and allow the material to be opened up and aerated as it is
forced through the process tube. Such raised details 63 are
depicted in FIG. 2 but are omitted from FIG. 1 for clarity.
[0075] The process tube 22 interior walls may have rifling or a cut
spiraled groove cut along its length to force the material to move
away from the centre in addition to shaped fins 63 mounted within
the process tube 22 to counteract the waste movement and push the
material towards the centre of the tube. These features can be used
individually or together, for example in alternation to move the
material radially within the tube leading to a greater agitation
and mixing, which leads to a better gas penetration and hence
higher gasification rate.
[0076] Referring to FIG. 3, the system is shown in combination with
a thermal oxidiser 65 in which process gas exiting the process tube
22 is thermally treated. The process gas is brought up to a
temperature in excess of 800.degree. C. for a period of around two
minutes so as to break down long chain hydrocarbons and VOC's
therein. This is done in a reduced oxygen environment so as to
prevent combustion of the process gasses. Heat may be provided by
means of a burner 66 in which a substantially stoichiometric
mixture of fuel, for example natural gas or syngas, and oxygen are
combusted. Some of the hot gasses from the thermal oxidiser 65 are
used as the conveying gas to both move the material through the
process tube 22 and to heat it. It will be appreciated that some
details of the system shown in FIGS. 1 and 2, for example the
compression of the gas and valving are omitted from FIG. 3 for
clarity.
[0077] In addition to the heat supplied by the hot process gases
additional means of heating 64 the process tube sections may be
provided in order to control the individual zone temperatures and
assist with the gasification process. These may be any known
heating means, for example electrical, or may use system heat, for
example they may circulate hot gasses from the thermal oxidiser 65
via recirculation conduits (not shown). This assists in ensuring a
finer control of the process chamber temperature throughout the
process, in particular it allows for fine control of the
temperature in each section, thereby leading to a better control of
the syngas quality of the process gas.
[0078] As described above the quality of the gas being produced can
be monitored. If the gas is of low quality then it can either be
sent to a separate chamber for conditioning, or alternatively can
be cycled through the thermal processing chamber 65 and
recirculated through the process tube until it reaches a desired
quality. Once the system is producing high quality process gas
(syngas) this can be removed from the system for use 68, or storage
for later use, for example to drive a syngas generator.
[0079] During some stages of the process where the temperature is
in particular ranges both carbon and coke can be formed in the
apparatus. During the carbon and coke period the process tube
sections, or the material therein, may be vibrated at the resonant
frequency of the coke particulates to separate the cokes from the
metal components, and intensify the gasification process of the
harder to gasify coke components. The vibration may be created by
back and forth pressure pulsing at the later stages to create
cycling of the pressure, this may for example be achieved through
the compressors or alternative vibration means (which may comprise
a pressure wave generator or mechanical vibrators) may be used.
This step will only be used at the later stage once most of the
gasification process is completed, and only harder particulates are
left, which will be mixed with or coating the metal fines.
[0080] Sensors for eddy currents and magnetic devices 67 may be
fitted to agitate the waste dust in the later process tube stages
to force the movement of the particles in a desired direction.
These devices will be added to enable finer control over the
gasification process toward the end of the process tubes when coke,
ferrous, and non-ferrous matter are left from the gasification
process. This agitation has a similar effect as the mechanical
vibration in that it can help separate the coke and carbon from the
metal and expose more of its surface area to the heat, thereby
assisting its gasification.
[0081] The movement of the material between the various process
tube sections will be fully controlled by controller 74 having a
control algorithm that evaluates the status of the waste and
process gas by receiving signals of process parameters from various
sensors that measure the syngas quality over the various pipe
zones, and other process parameters, for example temperature.
Although not shown it will be appreciated that the controller will
be connected to the various valves and sensors of the system to
receive information relating to the operating parameters, and for
sending control signals to the various valves, actuators and
heaters to operate the system. Based on the status of the waste,
the pressure, and syngas quality is changed. Furthermore, based on
the condition of the waste and the rate of the gasification, the
waste movement speed (residence time in each process tube section)
can be controlled. This gives an additional degree of freedom to
the gasification process, and allows the waste to be fully
gasified, or converted to coke, before entering the final pipe
sections in which the coke is then gasified.
[0082] With reference to FIGS. 4 and 5 the process tube 22 may be
constructed such to have an outer skin 69 and an inner skin 70
which may serve to support the waste material within the confines
of the inner skin 70 whilst allowing the inlet of the hot process
gas to pass into the inner processing tube 71, from the void 72
between the inner and outer skin, at certain sections of the
process tube 22 to aid a more effective waste degradation during
gasification. Alternatively, or in combination, the waste material
may be supported within the confines of the inner skin whilst
allowing the hot process gas to pass out of the confines of the
inner process tube 71 into the void 73 between the inner and outer
tube construction at certain zone sections of the process tube 22
to aid a more effective waste degradation during gasification. It
may be appreciated that the tube sections may take many cross
sectional forms in a number of combinations that differ from those
shown such as a round inner tube and a square outer tube for
example.
[0083] Referring to FIG. 6 a variation of the apparatus of FIG. 3
is shown. In this embodiment there are two thermal oxidisers 65 and
two outlet gas ducts 47. Each outlet gas duct 47 is connected to
the conduits 46 by valves 74, 75. The quality of the process gas
passing through the conduits 46 can be determined and depending on
the quality either the valve 74 or the valve 75 can be opened to
allow the process gas to pass through one outlet gas duct 47 or the
other. In use low quality process gas, which does not meet
predetermined criteria, will be routed through one outlet gas duct
47 and thermal oxidiser 65, which will treat the gas and
re-circulate it back through the process tube 22 as conveying gas.
Process gas above a certain quality will be routed through the
other outlet gas duct and thermal oxidiser this oxidiser will
thermally treat the gas and then the gas can either be
re-circulated to the process tube 22 or can be output for storage
or direct use, for example in a syngas engine to produce
electricity. Although shown with all stages of the process tube 22
connected to both outlet ducts 47, a variation is to only connect
the outlets of some of the sections of the processing tube 22 to
one outlet duct or the other. It may be that for the material being
processed it is known that the process gas from the first few
stages will never reach the required quality as in these stages
there are large amounts of volatiles and water vapour produced and
the gasification is only just starting. Accordingly it may be
appropriate that the outlet from these stages is always routed to
one of the thermal oxidisers. In contrast the process gas in the
last few stages, especially if the material has decomposed to
carbons and cokes, will be high grade process gas and may always be
routed to the other thermal oxidiser for treatment downstream
storage or use. In the central stages where the process gas will
shift in quality depending on the process parameters and the
material being processed it may be appropriate to connect the
conduits 46 to both conduits and control its flow with valves 74,
75 as described above in dependence on gas quality. An alternative
arrangement not shown in the figures may be to use a single thermal
oxidiser and to combust the lower quality process gas in the burner
by mixing it with the fuel prior to injection.
* * * * *