U.S. patent application number 13/029298 was filed with the patent office on 2012-08-23 for multi-ring plasma pyrolysis chamber.
This patent application is currently assigned to OAKS PLASMA LLC. Invention is credited to Alexandz Nikolaevich Bzatsev, Viktor Yevgenyevich Popov, Alexander Filippovich Rutberg, Philipp Grigorevich Rutberg.
Application Number | 20120210645 13/029298 |
Document ID | / |
Family ID | 46651262 |
Filed Date | 2012-08-23 |
United States Patent
Application |
20120210645 |
Kind Code |
A1 |
Rutberg; Alexander Filippovich ;
et al. |
August 23, 2012 |
Multi-ring Plasma Pyrolysis Chamber
Abstract
A pyrolysis chamber for the extraction of combustible gasses
from biomass waste such as wood chips has a gravity fed chamber,
where fuel passes, in succession, through a pre-heating zone, an
oxidation and reduction zone, a gas outlet zone and a solids
offloading zone. The pre-heating zone has plasma torches which
direct an air plasma into the chamber, thereby pre-heating the fuel
to a temperature of 1200-1500.degree. C., after which the fuel
enters the oxidation and reduction zone, where it is exposed to a
steam plasma of 1500.degree. C. which travels through plasma
torches to an annular ring distributor surrounding the chamber and
having apertures directing the steam plasma into the chamber,
thereby providing enhanced generation of combustible gasses of CO
and H.sub.2. The combustible gasses are removed in the gas outlet
zone, which has a half annular ring collector removing combustible
gasses out of the chamber and half annular ring distributor
injecting an air plasma into the chamber for gasification of the
ash residual carbon. A solids offloading part has a rotating grate
for the removal of ash and slag for delivery to a water trough.
Inventors: |
Rutberg; Alexander Filippovich;
(Madison, AL) ; Rutberg; Philipp Grigorevich;
(Saint Petersburg, RU) ; Bzatsev; Alexandz
Nikolaevich; (Saint Petersburg, RU) ; Popov; Viktor
Yevgenyevich; (Saint Petersburg, RU) |
Assignee: |
OAKS PLASMA LLC
AUSTIN
TX
|
Family ID: |
46651262 |
Appl. No.: |
13/029298 |
Filed: |
February 17, 2011 |
Current U.S.
Class: |
48/87 ;
48/197R |
Current CPC
Class: |
C10J 3/24 20130101; C10J
2300/1238 20130101; Y02E 20/16 20130101; C10J 3/74 20130101; C10J
2300/0976 20130101; C10J 3/26 20130101; C10J 3/42 20130101; C10J
2300/092 20130101; Y02P 20/129 20151101; C10J 2300/0956
20130101 |
Class at
Publication: |
48/87 ;
48/197.R |
International
Class: |
C10J 3/48 20060101
C10J003/48; C10J 3/72 20060101 C10J003/72 |
Claims
1) A pyrolysis chamber having a cylindrical body enclosing a
volume, the cylindrical body having: a neck region for the
introduction of fuel; a pre-heating region below said neck region,
said pre-heating region having at least one air plasma torch
directing air plasma into said pre-heating region; an oxidation and
reduction region below said pre-heating region, said oxidation and
reduction region including one or more steam plasma torches coupled
to an annular ring distributor formed into said cylindrical body,
said annular ring distributor having a plurality of apertures into
said enclosed volume; a gas outlet region below said oxidation and
reduction region, said gas outlet region including a half annular
ring distributor formed into said cylindrical body, said half
annular ring distributor coupled to at least one air plasma torch,
said half annular ring distributor having a plurality of apertures
into said enclosed volume, said outlet region also having a half
annular ring collector formed into said cylindrical body, said half
annular ring collector having a plurality of apertures coupled to
said enclosed volume and also having a gas outlet port for the
removal of combustible gasses produced inside said enclosed volume;
a solids offloading zone below said unloading region for the
removal of ash and slag, said solids offloading zone including a
grate having apertures for the removal of ash and slag, said
apertures coupled to a water filled trough, said water filled
trough also enclosing a perimeter of said enclosure thereby forming
an airtight seal.
2) The pyrolysis chamber of claim 1 where said pre-heating air
plasma torch has an arc length greater than 0.3 m.
3) The pyrolysis chamber of claim 1 where said pre-heating air
plasma torch generates an air plasma with a temperature greater
than 2000.degree. C.
4) The pyrolysis chamber of claim 1 where said oxidizing and
reduction steam plasma torch generates a steam plasma with a
temperature greater than 1500.degree. C.
5) The pyrolysis chamber of claim 1 where said oxidation and
reduction zone annular ring distributor is located within an inner
and outer wall of said chamber.
6) The pyrolysis chamber of claim 1 where said neck region
including a hopper for controlling the introduction of said
fuel.
7) The pyrolysis chamber of claim 1 where said grate having
apertures rotates below a stationary enclosure.
8) The pyrolysis chamber of claim 1 where said ash and slag is
removed from said trough.
9) The pyrolysis chamber of claim 1 where said half annular ring
distributor, said half annular ring collector, and said annular
ring distributor are formed in said chamber wall and lined with
refractory brick.
10) The pyrolysis chamber of claim 1 where said plurality of
apertures for at least one of said annular ring distributor, said
half annular ring distributor, or said half annular ring collector
are oriented downward into the volume of said chamber.
11) A process for extraction of combustible gasses from a fuel, the
process having: a first step of loading fuel into a pre-heating
zone, the pre-heating zone heated by a plurality of air plasma
torches coupling air plasma into the chamber and thereby forming
pre-heated fuel; a second step of exposing said pre-heated fuel to
a steam plasma generated by a steam plasma torch coupling the steam
plasma into an annular ring distributor in the chamber and
surrounding the pre-heated fuel, coupling the steam plasma in the
annular ring distributor to the pre-heated fuel using a plurality
of apertures, thereby reducing and oxidizing the pre-heated fuel
and generating combustible gasses and waste products of ash and
slag; a third step of gasification by injecting an air plasma into
the oxidized and reduced fuel with a half annular ring distributor
having a plurality of apertures directing the combustion gasses
into the outlet zone; a fourth step of removing the combustible
gasses by means of a half annular ring collector having a plurality
of apertures connecting the chamber with the half annular ring
collector directing the combustible gases to the external equipment
for energy extraction; a fifth step of removing ash and slag waste
products by exposing the oxidized and reduced fuel to a rotating
grate having apertures for removing ash and slag solids which have
a grain size smaller than the apertures of the rotating grate, ash
and slag solids which pass through the rotating grate thereafter
coupled to a waste accumulation reservoir.
12) The process of claim 11 where said pre-heating torch generates
an air plasma with a temperature above 1500.degree. C.
13) The process of claim 11 where said steam plasma torch generates
a steam plasma with a temperature above 1500.degree. C.
14) The process of claim 11 where said combustible gasses include
CO and H.sub.2.
15) The process of claim 11 where said air plasma and said steam
plasma are adjusted for delivery volume to optimize for the
generation of combustible gasses.
16) The process of claim 11 where at least one of said air plasma
or said steam plasma includes a post-plasma air introduction to
regulate the plasma temperature to a desired range.
17) The process of claim 11 where at least one of said third step
annular ring apertures or said fourth step annular ring apertures
are directed downward.
18) An apparatus for pyrolysis having: an enclosed chamber; a fuel
introduction zone for the introduction of fuel at the top of said
chamber; a pre-heating zone below said fuel introduction zone for
the introduction of air plasma into introduced fuel, thereby
forming pre-heated fuel; an oxidation and reduction zone below said
pre-heating zone, said oxidation and reduction zone having an
annular ring distributor formed into the walls of said enclosed
chamber, said annular ring distributor coupled to said enclosed
volume through a plurality of apertures, said annular ring
distributor coupled to one or more plasma torches generating a
steam plasma coupled into said annular ring distributor, each said
plasma torch fed with a source of steam; a gas outlet zone below
said oxidation and reduction zone, said gas outlet zone having a
half annular distribution ring with a plurality of apertures
coupled into said enclosed chamber on one half of said enclosed
chamber said half annular distribution ring coupled to one or more
air plasma torches, said gas outlet zone also having a half annular
collection ring with a plurality of apertures coupled into said
enclosed chamber on an opposite half of said enclosed chamber from
said half annular distribution ring, said half annular collection
ring coupled to a gas outlet; a solid waste offloading zone below
said gas outlet zone, said solid waste offloading zone adjacent to
a grate with apertures for the removal of ash and slag from the
fuel of said oxidation and reduction zone.
19) The apparatus of claim 18 where at least one of: said oxidation
and reduction annular ring distributor; said gas outlet zone
annular ring collector; said gas outlet zone annular ring
distributor; is formed into the walls of said enclosed volume.
20) The apparatus of claim 18 where at least one of: said oxidation
and reduction annular ring distributor apertures; said gas outlet
zone annular ring collector apertures; said gas outlet zone annular
ring distributor apertures; are disposed about the inner wall of
said enclosed chamber, said apertures directed downward toward said
solid waste offloading zone.
Description
FIELD OF THE INVENTION
[0001] The current invention is drawn to the field of Pyrolysis
chambers and processes. More specifically, the invention relates to
a top-loading Pyrolysis chamber for organic fuel such as wood
chips, the chamber having a plurality of air plasma torches for
pre-heating, steam plasma torches coupled to an enclosed annular
ring distributor for uniform steam plasma application during
oxidation and reduction, air plasma torches coupled to an enclosed
half annular ring distributor for introduction of air plasma into
outlet zone for removing ash and slag and a half annular ring
collector for collection and offloading of combustible gasses.
BACKGROUND OF THE INVENTION
[0002] Pyrolysis is commonly defined as the thermal decomposition
of an organic fuel in an environment of less-than-stoichiometric
oxygen, and devices utilizing this process are known as partial
oxidation reactors. Devices utilizing organic combustion include
coal-based gasification projects, which use direct and incomplete
combustion of feed material to generate the necessary reaction
heat. One class of prior art device heats the organic feed material
only to the point of leaving a carbon-ash composite solid (known as
char) as a reactor product/waste. Another class of prior art device
utilizes this residual char material as an external combustion fuel
to generate the required process reaction heat. In one such device,
the char is burned outside the pyrolysis reactor to generate the
required heat, and the resulting hot char recycled to heat the
incoming feed fuel. Another prior art device uses pure oxygen or
oxygen-enriched air to increase the temperature in the reactor,
since standard air combustion will provide a maximum reactor
temperature of only 1000-1100.degree. C. Oxygen-enrichment can also
be used to reduce the formation of undesired NOx gasses from
atmospheric N.sub.2 (nitrogen) present in the chamber.
[0003] The combustion of organic material such as wood chips
generates ash as a waste product. As the reaction temperature
increases to 1100-1500.degree. C., for certain compositions, the
ash will melt into a viscous material known as slag. Additionally,
metals which may be present in the ash will also melt into the slag
when the respective metal melting point temperature is reached,
which starts for many metals at temperatures above 1500.degree.
C.
[0004] In the Pyrolysis process, the ratio by volume of waste (ash
and slag) to incoming fuel is 2-4% (representing a 25.times. to
50.times. reduction in fuel volume), depending upon the amount of
noncombustible materials in the mixed wastes. By contrast, an
efficiently-operated conventional incinerator produces a solid
residue of 10% or more of the volume of refuse burned.
[0005] Prior art low temperature wood waste gasification operates
in the range of 800-900.degree. C. and yields 70-140 m.sup.3 per
ton, recovering no more than 8-12% of potential heat contained in
the fuel. The pryrolysis apparatus and method operates at maximum
efficiency for fuel generation and waste volume reduction at
increased temperatures, and as described above, these elevated
temperatures may be reached using oxygen enhanced combustion air,
but the use of oxygen represents an additional operational expense.
It is therefore desired to provide an improved pyrolysis chamber
with increased internal operating temperature and resultant
efficiency without the use of oxygen enriched air.
OBJECTS OF THE INVENTION
[0006] A first object of the invention is a Pyrolysis chamber
having a top-loading hopper where fuel is introduced and gravity
fed into to a pre-heating zone which includes a plurality of air
plasma torches directly coupling an air plasma into the chamber
thereby pre-heating the fuel, after which the pre-heated fuel is
gravity fed into an oxidation and reduction zone where a plurality
of steam plasma torches couple high temperature steam plasma into
an annular ring distributor having many apertures which uniformly
couple the steam plasma into the pre-heated fuel of the oxidation
and reduction zone, where the oxidizing fuel is spent and releases
combustible gasses, particularly H.sub.2 and CO, and these
combustible gasses are separated from the spent fuel in a gas
outlet zone having a half annular ring collector with many
apertures for collection and offload of the combustible gases for
subsequent utilization. Opposite the half annular ring collector is
a half annular ring distributor which is fed by an air plasma torch
coupling an air plasma into the gas outlet zone of the enclosure.
Below the gas outlet zone is a solids offloading zone having a
rotating grate with apertures for collecting the waste solids and
transferring them into a water trough which also provides a water
seal for the pyrolysis chamber. The water trough may also provide
means for the removal and disposition of ash and slag waste.
[0007] A second object of the invention is a process for pyrolysis
in a chamber, the process having:
[0008] a first step of loading fuel into a pre-heating zone, the
pre-heating zone heated by a plurality of air plasma torches
coupling an air plasma into the chamber and thereby forming
pre-heated fuel;
[0009] a second step of exposing the pre-heated fuel to an
oxidation and reduction zone where a steam plasma torch generates a
steam plasma which is delivered to an annular ring distributor with
apertures coupled to the chamber, the annular ring distributor and
apertures surrounding the pre-heated fuel and coupling the steam
plasma to the pre-heated fuel, thereby releasing combustible gasses
and solid waste products of ash and slag;
[0010] a third step of introducing an air plasma from an air plasma
torch into the oxidized and reduced fuel (char and ash), where the
air plasma is delivered to a half annular ring distributor with
apertures coupled to the chamber, the half annular ring distributor
and apertures delivering air plasma to the oxidized and reduced
fuel, thereby gasifying the char and forming ash residue ;
[0011] a fourth step of removing the combustible gasses using a
half annular ring collector for collection and offload of the
combustible gases, the combustible gases moving through a plurality
of apertures into the half annular ring collector and carried out
of the chamber;
[0012] a fifth step of removing ash and slag waste products by
exposing the oxidized and reduced fuel to a rotating grate which
has apertures larger than an ash or slag grain size, the ash and
slag passing through the rotating grate and transferred to the a
trough.
SUMMARY OF THE INVENTION
[0013] A Pyrolysis chamber has, in succession, a fuel loading zone,
a fuel pre-heating zone, a steam plasma oxidizing and reduction
zone, a gas outlet zone including a combustible gas outlet, and a
solids offloading zone for removing ash and slag. The fuel
pre-heating zone has a plurality of air plasma torches which couple
a 1200-1500.degree. C. air plasma into the chamber and heat the
fuel to a pre-heat temperature of approximately 1200-1500.degree.
C., after which the pre-heated fuel is exposed to a steam plasma of
approximately 1500.degree. C. which is generated by a plurality of
steam plasma torches which first couple the steam plasma into an
annular ring distributor within the walls of the chamber, the
annular ring distributor containing a plurality of apertures into
an oxidation and reduction zone of the chamber, whereby the steam
plasma and pre-heated fuel oxidize and reduce to generate
combustible gasses and waste solids. The combustible gasses and
solid waste are thereafter directed towards a gas outlet zone which
is formed by the half annular ring distributor and the half annular
ring collector. The half annular ring distributor is pressurized by
a plurality of air plasma torches coupling an air plasma into the
half annular ring distributor within the chamber walls, the half
annular ring distributor having a plurality of apertures conducting
the air plasma into the gas outlet zone. The half annular ring
collector contains a plurality of apertures coupled to the chamber
for drawing the combustible gasses out of the chamber and to
external equipment such as a steam turbine or internal or external
combustion engine for energy extraction. Below the gas outlet zone
is a solids offloading zone with a rotating grate for removal of
slag and ash, the rotating grate having apertures for solids
removal and in contact with a water trough for aggregation of
solids and slag removal.
[0014] In another embodiment of the invention, a process for
pyrolysis in a chamber has a first step of loading fuel into a
pre-heating zone, the pre-heating zone heated by a plurality of air
plasma torches coupling air plasma into the chamber and thereby
forming pre-heated fuel;
[0015] a second step of exposing pre-heated fuel to a steam plasma
generated by a steam plasma torch coupling the steam plasma into an
annular ring distributor in the chamber and surrounding the
pre-heated fuel, coupling the steam plasma in the annular ring
distributor to the pre-heated fuel using a plurality of apertures,
thereby oxidizing and reducing the pre-heated fuel and generating
combustible gasses and waste products of ash and slag; a third step
of gasification of the ash residual carbon by injecting an air
plasma into the oxidized and reduced fuel with a half annular ring
distributor having a plurality of apertures directing the air
plasma into the outlet zone;
[0016] a fourth step of removing the combustible gasses by means of
a half annular ring collector having a plurality of apertures
coupling the chamber with the half annular ring collector and
directing the combustible gases to the combustible gas outlet for
energy extraction;
[0017] a fifth step of removing ash and slag waste products by
exposing the oxidized and reduced fuel to a rotating grate having
apertures for removing ash and slag solids which have a grain size
smaller than the apertures of the rotating grate, ash and slag
solids which pass through the rotating grate thereafter coupled to
a waste accumulation reservoir.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows the cross section diagram of a plasma pyrolysis
chamber.
[0019] FIG. 2 shows the cross section view through section A-A of
FIG. 1.
[0020] FIG. 3 shows the cross section view through section B-B of
FIG. 1.
[0021] FIG. 4 shows a cross section view of the walls of a
pyrolysis chamber.
DETAILED DESCRIPTION OF THE INVENTION
[0022] The present invention describes an apparatus and method for
pyrolytic waste recovery which can extract energy in the form of
combustible gases from a wide variety of heterogeneous organic
materials including municipal refuse, biomass, agriculture wastes,
wood and forest product processing wastes, hazardous wastes,
petroleum coke, coal or oil shale, individually or as mixtures.
Depending on the nature of the input fuel, the resultant
combustible gas is suitable use as a fuel for electric power
generation, for conversion to synthetic hydrocarbons, hydrogen, or
other valuable chemicals. In one embodiment of the invention, the
combustible gas includes H.sub.2 and CO and a steam plasma is
injected in the oxidation and reduction zone which generates these
gasses, the steam plasma containing sufficient energy to compensate
for the endothermic heat required to generate these combustible
gasses. In another embodiment of the invention, the fuel is wood
chips or other biomass fuel. The instant process operates with a
volume reduction on the order of 20.times. of input fuel volume and
a weight reduction on the order of 10.times. in fuel with respect
to the waste ash and slag.
[0023] In one prior art system described in U.S. Pat. No.
7,452,392, oxygen is removed from a combustible gas stream by
oxidizing a portion of the fuel with less than the stoichiometric
amount of oxygen, typically as close to 50% as possible. Steam is
also added to the combusted gases in deliberately controlled
quantity. This process reaction, known as gaseous partial
oxidation, is quick, complete (in terms of oxygen removal extent),
and generates significant heat as it is highly exothermic.
[0024] Many different fuels may be used in the present device,
including those listed in the table below:
TABLE-US-00001 Material Type BTU/lb Cardboard/Kraft Paper 6233
Paper/Newsprint High Grade Paper/Magazines/ Paper 5446 Phone Books
Other Mixed & Paper 5481 Waste Paper CRV/PET Plastic 13200
HDPE, LDPE, PP Plastic 13800 PVC Plastic 8000 Polystyrene (PS)
Plastic 17700 Rubber/Tires (w/o metal) Plastic 8443 Other Plastic
Plastic 12000 Yard Waste Organics 4500 Food Waste, Dead Animals
Organics 3265 Wood Waste Organics 6933 Textile Organics 6595
Leather Organics 8433 Misc. Organics Organics 6600 Disposable
Diapers Other 4500 Asphalt Other 14000 Glass Glass 0 Aluminum,
Ferrous Metal, Metals 0 Other metals Concrete, Clay, Inerts 0
Brick, Rock, Sand, Soil, Ash, Other Inerts Paint HazWaste 200 Motor
Oil HazWaste HazWaste 19000 Lead Acid Batteries HazWaste 0 Other
Household Waste HazWaste 3000 Municipal Solid Waste (MSW) Waste
4560
[0025] FIG. 1 shows a plasma pyrolysis chamber 100. Feed fuel 102
is placed above a controllable feed valve 104, which periodically
opens and introduces new fuel 102 from a hopper above feed valve
104 through throat 108 and into the pryolysis chamber 109, which
has a fuel pre-heating zone 140 heated by air plasma torches 110
and 112, an oxidation and reduction zone 142 where steam plasma is
introduced using steam plasma torch 126, and gas outlet zone 143
where air plasma torch 134 introduces air plasma through half
annular ring distributor 135. Combustible gas 137 formed in the
oxidation and reduction zone 142 and also from the gasification of
the char is removed using half annular ring collector 136 in gas
outlet zone 143 to outlet port 139, and slag and ash are removed
from the pyrolysis chamber in solids offloading zone 144.
[0026] The preheat zone 140 provides for introduced fuel 122 to be
heated to approximately 1200-1500.degree. C. through the rapid
introduction of air plasma at a temperature of 2000-4000.degree. C.
through air plasma torches 110 and 112, where air 114, 118 is
forced through the plasma torches 110 and 112, respectively, which
air plasma 116, 120, respectively, exits directly into the chamber
pre-heated fuel 122, is gravity packed with a fuel/air volume ratio
preferably on the order of 1:1 and a fuel density range of 180-800
kg/m.sup.3, with 400 kg/m.sup.3 being a typical density. The
pre-heated fuel 122 is then subjected to a steam plasma which is
generated by steam 124 injected into plasma torch 126, and the
resultant steam plasma which is at a temperature of approximately
1500 degrees C. is then directed through an annular ring
distributor 128 formed in chamber 109, then through a plurality of
apertures 202 (shown in FIG. 2) directing the steam plasma downward
into the chamber and into the oxidation and reduction zone 142 in
region 130 of chamber 109, where the following basic reactions take
place:
C+CO2.fwdarw.2CO (Eq 1)
C+H.sub.2O.fwdarw.CO+H.sub.2-31.2Kcal/mole of C (Eq 2)
CO+H.sub.2O.fwdarw.CO.sub.2+H.sub.2 (Eq 3)
Equation 1 is known as Bouduart reaction, equation 2 is known as
the water gas shift reaction, and equation 3 is known as the
hydrogen shift equation. Equations 1 and 2 are endothermal, and the
use of a steam plasma 128 at 1500.degree. C. or more in this stage
introduces sufficient external energy to offset the endothermic
heat loss during combustible gas (CO and H.sub.2) generation. The
combustible gasses 123 and 125 migrate to the gas outlet zone 143,
via the apertures 304 (described later for FIG. 3), where they
enter into the half annular ring collector 136 directing the
combustible gases 137 to an outlet port 139 directed to an energy
extraction device such as a gas turbine. Air 132 enters air plasma
torch 134 and exiting air plasma is coupled to a half annular ring
distributor 135, coupling air plasma into the chamber volume 138
via apertures 302 (shown in FIG. 3), the air plasma acting on the
oxidized and reduced fuel 127 and the gasified ash residual carbon.
When the pyrolysis process is carefully regulated through the
metered introduction of steam plasma and air plasma into the
reaction chamber, minimal reaction of nitrogen (present in the air
plasma as it is derived from atmospheric air) occurs, and the
generation of combustible gasses CO and H.sub.2 results in decrease
of the nitrogen as a percentage of volume of the gas 137 which
exits the outlet port 139. The oxidized and reduced fuel char 138
is thereby reduced to ash, and at temperatures above 1500.degree.
C. the ash vitrifies into slag, and the ash and slag pass through a
rotating grate 150 which is above a water bath 158 in trough 162,
which isolates air outside chamber 109 from the inner volume of the
pyrolytic chamber 109, and also provides a collection region for
ash and slag 154 which passes through the apertures of grate 150,
into the trough 162, and eventually is removed by ash and slag
conduit 160.
[0027] FIG. 2 shows section A-A of FIG. 1 including steam plasma
annular ring distributor 128, and also shows the steam plasma
directed from steam plasma torches 126 through the annular ring
distributor 128, through the plurality of apertures 202 into fuel
130 which is oxidizing and reducing to generate combustible gas.
FIG. 3 shows section B-B of FIG. 1 through the inlet air plasma
half annular ring distributor 135 and also the half annular ring
collector 136 accumulating the combustible gas 137, which leads to
gas outlet port 139.
[0028] FIG. 4 may be viewed in combination with FIGS. 1, 2, and 3,
and shows one embodiment for construction of the walls of chamber
109 of FIG. 1, including the steam plasma annular ring distributor
128 for region 180, air plasma half annular ring distributor 135
for region 182, and half annular ring collector 136 of region 184
(shown for reference as rotated for the opposite side of region
182). In the example embodiment shown in FIG. 4, firebrick 400 may
be used to form the structure of the enclosure 109, with refractory
brick 404 applied to the combustion-facing surfaces and also inside
the air or steam plasma channels feeding the annular ring
distributor 128 for FIG. 1 detail 180, half annular ring
distributor 135 shown in FIG. 1 detail 182, or half annular ring
collector 136 shown in FIG. 1 detail 184. The apertures 202, 302,
304 for annular ring distributor 128, half annular ring distributor
135, and half annular ring collector 304, respectively, are shown
in FIG. 4 oriented downward into the pyrolysis chamber to minimize
blockage of the port apertures 202, 302, and 204 from char, ash,
and slag in the pyrolysis chamber. Additionally, in one embodiment
of the invention, any of the annular rings 128, 135, and 136 may be
formed with expansion joints in the refractory brick lining, such
that thermal expansion and contraction is absorbed by these joints.
The pre-heating torches produce an air plasma which is directly
introduced into the chamber through a passageway. A material such
as thermostable steel may be used as an exterior surface 402 of the
chamber 109. Inner surfaces which are combustion facing or plasma
facing may be provided with furnace linings of aluminum oxide,
magnesite (magnesium carbonate), silicon carbide, or dolomite as is
known in the prior art to increase the useful life of the
underlying surfaces protected by these furnace linings.
[0029] The high speed pyrolysis of the current system has several
advantages over a prior art pyrolysis system, including a greater
conversion fraction of the incoming waste to combustible gas.
Thermal or normal pyrolysis promotes liquefaction giving only
45-50% conversion to pyrolysis gases, while rapid pyrolysis of the
present invention has gas yields of greater than 65%.
[0030] Many methods for extraction of energy from the combustible
gasses 137 using the gas outlet port 139 are possible. With the
efficiency of gas turbine-combined cycle systems approaching 60%,
the present method of waste-to-energy conversion provides an
effective alternative to standard waste incinerators. Under
favorable conditions, the incinerator-steam generator systems
achieve 15-20% efficiency in the conversion of the potential energy
contained in the waste to usable electric energy. In one example
system, 1 Kg of incoming waste generates 14-15 MJ of chemical
energy at the combustible gas outlet port, and 2-3 MJ of electrical
energy is consumed in the generation of the various plasmas which
feed the chamber.
[0031] The specific gravity of slag will be on the order of 2.0-2.5
which will allow it to adequately gravity feed through the
apertures of the grate. The solid vitrified waste products produced
in accordance with the present invention when the oxidation and
reduction temperatures are sufficiently high may be used in a
variety of applications. The vitrified slag waste may be crushed
and incorporated into asphalt for use in roads and the like.
Alternatively, the vitrified slag may be utilized to replace cinder
in cinder or building blocks, thereby minimizing absorption of
water within the block. Further, the vitrified slag may be
solidified to a final form which exhibits substantial volume
reduction over prior art vitrification products. The solidified
form is suitable for disposal without health risks or risks to the
environment.
[0032] Pre-heating plasma torches (110,112), steam plasma torch
(126) and air plasma torch (134) gasifying the ash residual carbon
can be realized using any prior art long arc torch configuration,
and operative on 4-12 KV with an arc length greater than 0.3 m.
Although specific numbers of plasma torches are shown for clarity,
any number of torches may be used in each respective pre-heat zone
(torch 110, 112), oxidation and reduction zone (torch 126), and gas
outlet zone (torch 134). Many different prior art embodiments of
the plasma torch can be utilized in the present invention. In one
embodiment, each torch is a long arc forming plasma torch of the
type described in U.S. Pat. No. 3,818,174 for a single phase
excitation, or as described in U.S. Pat. No 7411,353 by Routberg et
al. for polyphase excitation. Long arc column plasma torches have
become well known in the art as having the capability of sustaining
stabilized plasma arcs on the order of one meter in length. In
contrast, conventional short arc plasma torches generally sustain
arcs of less than 0.2 meter and typical non-plasma electric arc
devices have no stabilizing character and produce relatively short
arcs. The apparatus and method of the invention recognize and
utilize features of the long arc torch which makes its stabilized,
electrically conducting gas column especially suited for use with
gasification of coal as a source of radiant heat and particularly
when used in multiple and arranged as described with the "long arc"
being at least 0.3 meter in length.
[0033] One advantage of long plasma arc torches such as those
described above is the conversion of electrical energy to heat with
an efficiency of approximately 90% as compared with an efficiency
of 30-50% for conventional short arc torches. Further, it is
recognized that the capability of the long arc torch in combination
with the annular ring distribution is that the torches are now
placed outside of the furnace wall and away from the intense
furnace heat produced during gasification. This advantage reduces
the wear on the torch and increases the thermal efficiency of the
process. Also, the invention recognizes that the long arc torch
requires significantly less current than a conventional torch
thereby reducing the cost of electrical conductors and reducing the
complexity of the electrical power connections.
[0034] Chamber 109 including annular ring plasma distributors 128
and 135 and half annular ring collector 136 may be formed using any
material which provides resistance to surface degradation from
exposure to the high temperature plasma and pyrolysis process.
Suitable materials include brick with a refractory brick (fire
brick) lining with a typical maximum temperature of 1650.degree.
C., or steel treated with an insulating material. In another
embodiment, a chamber for 100 kg/hr wood waste has an inside
dimension of 0.6 m and a preheat zone, oxidation and reduction
zone, gas outlet zone, and solids offloading zone with 1.9 m
overall vertical extent, with the chamber constructed of heatproof
steel with the high temperature areas insulated with aluminum
oxide.
[0035] Many different embodiments of the present invention are
possible, and those shown are for clarity in understanding the
invention, and do not limit the invention, which is understood as
set forth in the claims below.
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