U.S. patent application number 12/856046 was filed with the patent office on 2011-02-10 for side feed/centre ash dump system.
Invention is credited to Dave Berner, Kenneth Davison, Neal Stroulger.
Application Number | 20110030590 12/856046 |
Document ID | / |
Family ID | 36481128 |
Filed Date | 2011-02-10 |
United States Patent
Application |
20110030590 |
Kind Code |
A1 |
Davison; Kenneth ; et
al. |
February 10, 2011 |
SIDE FEED/CENTRE ASH DUMP SYSTEM
Abstract
An apparatus for gasifying solid organic fuel includes a
refractory-lined oxidation chamber, fuel storage, a transfer
connecting the fuel storage with an inlet into the oxidation
chamber for transferring in an upwardly inclined direction the
solid fuel from the fuel storage into the inlet to form an upwardly
mounded fuel bed. An oxidant is supplied into the fuel bed to
gasify the organic materials in the fuel to produce a gaseous
effluent from the fuel bed, thereby leaving a residue of the fuel.
The residue drops through an opening under the oxidation chamber
onto a residue removal transfer. The oxidant is supplied through a
plurality of perforated air distribution members extending across
the fuel bed cavity in the oxidation chamber so as to introduce air
into the interior of the fuel bed to thereby promote evenly
distributed gasification, evenly distributed through the fuel
bed.
Inventors: |
Davison; Kenneth; (Lake
County, CA) ; Stroulger; Neal; (Kamloops, CA)
; Berner; Dave; (Spruce Grove, CA) |
Correspondence
Address: |
HOLLAND & KNIGHT LLP
10 ST. JAMES AVENUE
BOSTON
MA
02116-3889
US
|
Family ID: |
36481128 |
Appl. No.: |
12/856046 |
Filed: |
August 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11285145 |
Nov 23, 2005 |
7793601 |
|
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12856046 |
|
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60629972 |
Nov 23, 2004 |
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Current U.S.
Class: |
110/229 ;
110/342 |
Current CPC
Class: |
C10J 2300/0946 20130101;
C10J 2300/1876 20130101; C10J 2300/0956 20130101; C10J 2200/158
20130101; C10J 3/22 20130101; F23G 7/10 20130101; C10J 2300/0916
20130101; C10J 3/36 20130101; F23G 5/0276 20130101; C10J 2200/15
20130101; C10J 2200/152 20130101; F23G 5/46 20130101; F23G 2201/303
20130101; C10J 2300/0959 20130101; C10J 3/34 20130101; F23B 90/06
20130101; C10J 2200/09 20130101 |
Class at
Publication: |
110/229 ;
110/342 |
International
Class: |
F23G 5/12 20060101
F23G005/12 |
Claims
1. An apparatus for gasifying solid fuel including solid organic
materials comprising: a primary oxidation chamber having an inner
surface lined with a refractory material to promote catalytic
oxidation of the solid organic materials, said primary oxidation
chamber having an open-bottomed bottom portion and an enclosed
upper portion, said upper portion for mixing of gaseous material in
said chamber, said bottom portion having an inlet opening for
infeed of the solid fuel, means for storing the solid fuel,
transfer means connecting said means for storing with said inlet
opening and for transferring in an upwardly inclined direction the
solid fuel from said means for storing the solid fuel through said
inlet opening into said primary oxidation chamber to form an
upwardly mounted fuel bed of the solid fuel including the organic
materials in said bottom portion of said primary oxidation chamber,
means for supplying an oxidant into said fuel bed in said bottom
portion of said primary oxidation chamber supplies a first oxidant
to gasify the solid organic materials to produce gasified organic
materials including a first gaseous effluent from the fuel bed,
thereby leaving a residue of said fuel, wherein said means for
supplying said oxidant includes a plurality of perforated air
distribution members extending across a fuel bed cavity in said
bottom portion and through said fuel bed, adjacent to fuel driven
upwardly into said fuel bed through said inlet opening, so as to
introduce air into said interior of said fuel bed to thereby
promote evenly distributed gasification, evenly distributed through
said fuel bed, wherein said open-bottomed bottom portion has
mounted thereunder, and is open over, means for the removal of said
residue of the fuel, whereby said residue falls from said bottom
portion onto said means for removal of said residue, cooperating
with the primary oxidation chamber, a means for removing said first
gaseous effluent from said upper portion of said primary oxidation
chamber.
2. The apparatus of claim 1 wherein said means for supplying an
oxidant into said primary oxidation chamber adds said first oxidant
at a predetermined flow rate to maintain a desired flow rate of
said first gaseous effluent from said primary oxidation chamber,
and wherein said predetermined flow rate of said first oxidant is a
relatively low flow rate so as to not suspend particulate matter
from said fuel or residue from the gasifying of solid organic
materials in said fuel into said first gaseous effluent.
3. The apparatus of claim 2 further comprising a secondary
oxidation chamber cooperating in fluid communication with said
upper portion of said primary oxidation chamber, said secondary
oxidation chamber receiving said first gaseous effluent from said
primary oxidation chamber, and further comprising a means for
supplying a second oxidant to said first gaseous effluent in said
secondary oxidation chamber so as to supply a second oxidant into
said secondary oxidation chamber to produce a second gaseous
effluent, said second gaseous effluent an oxidized product of said
first gaseous effluent, to thereby release energy from said first
gaseous effluent.
4. The apparatus of claim 3 further comprising means for recovering
said energy as recoverable heat energy and means for withdrawing
said second gaseous effluent from said secondary oxidation
chamber.
5. The apparatus of claim 1 wherein said transfer means includes a
hydraulic ram feeder.
6. The apparatus of claim 1 wherein said transfer means includes a
fuel removal means for removing the fuel from said storage means
and for transferring the fuel to said feeder adjacent said inlet
opening of said primary oxidation chamber.
7. The apparatus of claim 1 wherein said transfer means includes a
feeder for forcefully delivering the fuel through said inlet
opening and an upwardly inclined passage cooperating with said
feeder and extending into said inlet opening of said primary
oxidation chamber, said passage upwardly inclined so that the fuel
is forced by the feeder into said bottom portion of said primary
oxidation chamber in an upwardly inclined direction so as to drive
the fuel upwardly into said fuel bed, toward an upper surface of
said bed maintained above said inlet opening.
8. The apparatus of claim 1 wherein said bottom portion is
open-bottomed so that said residue as it migrates downwardly below
the fuel entering said fuel bed to a bottom of said fuel bed for
removal therefrom by said means for the removal of said
residue.
9. The apparatus of claim 8 wherein said means for the removal of
said residue includes a walking-floor feeder wherein a
reciprocating rack having upstanding rigid members slides
reciprocally relative to a fixed floor so as to urge said residue
at said bottom of said fuel bed out from underneath said bottom
portion.
10. The apparatus of claim 5 wherein said fuel removal means
includes a walking-floor feeder wherein a reciprocating rack having
upstanding rigid members slides reciprocally relative to a fixed
floor under the fuel being stored.
11. A method for gasifying solid fuel including solid organic
materials comprising the steps of a) providing a primary oxidation
chamber having an inner surface lined with a refractory material to
promote catalytic oxidation of the solid organic materials, said
primary oxidation chamber having a bottom portion and an upper
portion, said upper portion for mixing of gaseous material in said
chamber, said bottom portion having an inlet opening for infeed of
the solid fuel, b) providing a means for storing the solid fuel, c)
providing a transfer means connecting said means for storing the
solid fuel with said inlet opening, d) providing a means for
supplying oxidant into said bottom portion which includes a
plurality of air distribution members extending across said bottom
portion and adjacent to fuel driven into said bed through said
inlet opening so as to introduce air into said interior of a fuel
bed formed in said bottom portion to thereby promote evenly
distributed gasification, evenly distributed through said fuel bed,
wherein said plurality of air distribution members include
perforated members extending across a cavity of said bottom portion
so as to promote infiltration of the oxidant throughout the fuel
bed, e) transferring the solid fuel from said means for storing the
solid fuel through said inlet opening into said primary oxidation
chamber to form said fuel bed of the solid fuel including the
organic materials in said bottom portion of said primary oxidation
chamber, f) supplying a first oxidant into said bottom portion of
said primary oxidation chamber to gasify the solid organic
materials to produce gasified organic materials including a first
gaseous effluent from the fuel bed, thereby leaving a residue of
said fuel, g) removing residue of the fuel from under said bottom
portion by means for the removal of said residue of the fuel, h)
removing said first gaseous effluent from said upper portion by a
means for removing said first gaseous effluent from said upper
portion cooperating with said primary oxidation chamber.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional
Patent Application No. 60/629,972 filed Nov. 23, 2004 entitled Side
Feed/Centre Ash Dump System.
FIELD OF THE INVENTION
[0002] This invention relates to a method and apparatus for
gasifying solid organic materials to convert the chemical energy
stored in such materials to thermal energy. More particularly, this
invention relates to a method and apparatus for gasifying low or
high ash biomass materials. The high temperature gases produced by
the practice of the invention can be utilized to advantage, for
example, as the thermal energy source for conventional heat
exchange equipment such as boilers.
BACKGROUND OF THE INVENTION
[0003] On many conventional gasification systems there has been
difficulty in fuel delivery and ash removal from the gasifier
primary chambers. This has been especially apparent on high ash
fuels as well as fuels with low ash melting or fusion
temperatures.
[0004] It has been recognized that many industrial and agricultural
solid organic by-products, such as wood chips, agricultural waste,
and other biomass material, contain large amounts of chemical
energy. The substantial increases in the cost of traditional fuels,
such as natural gas, have provided substantial economic incentive
to try to develop effective and efficient techniques for recovering
the energy in these organic by-products, energy that traditionally
was not recovered to any substantial extent. Such organic
materials, which are frequently referred to as "biomass" materials,
are now successfully utilized to some extent as fuel in some very
large industrial systems, for example, in firing the recovery
boiler in a pulp or paper mill. However, the higher capital cost
which has heretofore been associated with biomass energy recovery
systems has precluded their successful use in small or even medium
size energy recovery systems. Energy recovery systems, of the size
from about 500,000 to 40,000,000 BTU/Hr., are used in schools,
nursing homes, and small industrial and commercial establishments.
Among the U.S. patents that have been issued on inventions relating
to the recovery of energy from wood chips or similar organic
materials are U.S. Pat. No. 4,184,436, to Palm, et al.; U.S. Pat.
No. 4,312,278, to Smith, et al.; U.S. Pat. No. 4,366,802, to
Goodine; U.S. Pat. No. 4,321,877, to Schmidt, et al.; and U.S. Pat.
No. 4,430,948, to Ekenberg. However, it is not known that any of
the inventions described in these patents have been successfully
adapted to recovering biomass energy on a cost-effective basis in
small and medium size energy recovery system. Dealing with high ash
fuels has proved especially difficult for many of these
processes.
SUMMARY OF THE INVENTION
[0005] In summary, the apparatus according to the present invention
for gasifying solid fuel including solid organic materials includes
a primary oxidation chamber advantageously having an inner surface
lined with a refractory material to promote catalytic oxidation of
the solid organic materials. The primary oxidation chamber has a
bottom portion and a converging upper portion, the latter to
facilitate mixing of gaseous material in the chamber. The bottom
portion has an inlet opening for infeed of fuel.
[0006] The apparatus further includes means for storing the solid
organic materials; transfer passage means connecting the means for
storing with the inlet opening for transferring the solid fuel from
the means for storing through the inlet opening into the primary
oxidation chamber to form a fuel bed of solid fuel including the
organic material in the primary oxidation chamber. A means for
supplying an oxidant into the primary oxidation chamber supplies a
first oxidant to gasify the solid organic materials to produce
gasified organic materials including a first gaseous effluent, and
thereby leaving a residue. The means for supplying the oxidant may
have a plurality of air distribution members extending across said
bottom portion and adjacent to fuel driven into said bed through
the inlet opening of the primary oxidation chamber so as to
introduce air into the interior of the fuel bed to thereby promote
evenly distributed gasification, evenly distributed through said
fuel bed.
[0007] The plurality of air distribution members include perforated
members extending across a cavity of the bottom portion so as to
promote infiltration of the first oxidant throughout the fuel
bed.
[0008] The bottom portion of the primary oxidation chamber
advantageously has mounted thereunder means for the removal of the
residue of the fuel, that is, the materials such as ash left in the
primary oxidation chamber after the solid organic materials have
been gasified. Further advantageously, a further means is disposed
within the primary oxidation chamber for establishing a gaseous
mixing flow path within the primary oxidation chamber for enhancing
the oxidation of the mass of the solid organic materials to produce
the first gaseous effluent. Cooperating with the primary oxidation
chamber is a means for removing the first gaseous effluent from the
primary oxidation chamber.
[0009] In a preferred embodiment, the means for supplying an
oxidant into the primary oxidation chamber adds the oxidant at a
predetermined rate to maintain a volume or flow rate of the first
gaseous effluent in the primary oxidation chamber. In a preferred
embodiment the predetermined flow rate of oxidant is a relatively
gentle flow rate so as to not blow or otherwise end-up suspending
particulate matter from the gasifying solid organic materials into
the first gaseous effluent. A secondary oxidation chamber may be
provided cooperating in fluid communication with the primary
oxidation chamber. The secondary oxidation chamber receives the
first gaseous effluent from the means for removing the first
gaseous effluent from the primary oxidation chamber. A means for
supplying a second oxidant to the first gaseous effluent in the
secondary oxidation chamber supplies a second oxidant into the
secondary oxidation chamber to produce a second gaseous effluent.
The second oxidant oxidizes the first gaseous effluent in the
secondary oxidation chamber to thereby release further energy from
the gasified effluent, preferably in the form of recoverable heat
energy which may be used in a heat exchanger for example. A means
for withdrawing the second gaseous effluent from the secondary
oxidation chamber removes the second gaseous effluent.
[0010] In one preferred embodiment, the means for supplying an
oxidant to the primary oxidation chamber may include a first air
blower mounted to the primary oxidation chamber, and the means for
supplying an oxidant to the secondary oxidation chamber may include
a second air blower mounted to the secondary oxidation chamber.
[0011] The transfer means for transferring the solid organic
materials from the means for storing into the primary oxidation
chamber may include, without intending to be limiting, a screw-type
feeder or hydraulic ram feeder. The transfer passage means may
include a fuel removal means for removing the fuel from the storage
means and for transferring the fuel to the feeder adjacent the
inlet opening of the primary oxidation chamber. The feeders may
advantageously include an upwardly inclined passage extending into
the inlet opening of the primary oxidation chamber, upwardly
inclined so that fuel is forced into the primary oxidation chamber
in an upwardly inclined direction. This drives un-oxidized fuel,
that is, new fuel upwardly into the bed of fuel being gasified in
the primary oxidation chamber so as to drive the fuel toward the
surface of the bed which is maintained above the level of the fuel
infeed or inlet opening. The residue or ash is left to migrate
downwardly below the new fuel and surface of the bed so as to
migrate to the bottom of the bed for removal therefrom.
[0012] The fuel removal means may include a first screw-type feeder
which may include a helical screw or auger mounted inside a passage
which may lead to either a second feeder such as a screw-type
feeder or a hydraulic ram feeder feeding into the inlet opening,
both serially disposed with respect of the first screw-type feeder.
The first screw-type feeder may alternatively be a walking-floor
feeder wherein a reciprocating rack having upstanding lugs,
corrugations, etc slides reciprocally relative to a fixed floor so
as to urge fuel piled on the floor in a direction towards the
second feeder.
[0013] Advantageously, the means for removing the first gaseous
effluent may include an insulated exit duct connecting the primary
oxidation chamber to the secondary oxidation chamber permitting the
secondary oxidation chamber to receive the first gaseous effluent
from the primary oxidation chamber, wherein the insulated exit duct
has a restricted entry portion to prevent the passage of a flame in
the primary oxidation chamber into the secondary oxidation chamber,
and wherein the restricted entry portion is disposed within the
primary oxidation chamber.
[0014] Further advantageously, the primary oxidation chamber may
have the shape of a generally vertically extending cylinder or box
having a vertically extending longitudinal axis and the converging
upper portion at one end thereof. The primary oxidation chamber may
maintain an angled or domed roof.
[0015] In one embodiment the means for removal of the solid residue
includes a continuous, such as auger, or intermittent, such as a
walking floor, ash removal system positioned at the bottom of the
primary oxidation chamber adjacent to the air distribution
member.
[0016] The means for supplying an oxidant into the primary
oxidation chamber may further include an air blower mounted to the
primary oxidation chamber, the air blower supplying air to the air
distribution member. The means for supplying an oxidant into the
primary oxidation chamber may further include a means for adding a
portion of the first oxidant into the transfer passage means so as
to intersperse with the solid organic materials being transferred,
and means for supplying a second portion of the first oxidant into
the primary oxidation chamber at least one location above the mass
of the solid organic materials to enhance gasification of the solid
organic materials.
[0017] According to one aspect of the invention there is provided a
method for gasifying solid organic materials to produce finished
gaseous effluent and solid residue, said method comprising the
steps of: providing a source of supply of solid organic materials;
providing a primary oxidation chamber having a bottom portion and a
converging upper portion to facilitate mixing of gaseous material
in said chamber; introducing solid organic materials from said
source of supply into said primary oxidation chamber to provide a
mass of said solid organic materials in said primary oxidation
chamber; heating said mass of organic materials in said primary
oxidation chamber; adding an oxidant to said primary oxidation
chamber to gasify said heated mass of solid organic materials in
said primary oxidation chamber and initiate a flow of gaseous
effluent within said primary oxidation chamber; establishing a
gaseous flow path within said primary oxidation chamber whereby
mixing and then advancing said gaseous effluent flow in a direction
outward from said primary oxidation chamber; and transferring said
solid residue out of said primary oxidation chamber.
[0018] The invention also provides an apparatus for gasifying solid
organic materials comprising: a primary oxidation chamber having an
inner surface lined with a refractory to promote oxidation of said
solid organic materials, said primary oxidation chamber having a
bottom portion and a converging upper portion to facilitate mixing
of gaseous material in said chamber, and an inlet opening provided
through said bottom or side portion; means for storing said solid
organic materials; transfer passage means connecting said means for
storing with said inlet opening for transferring said solid organic
materials from said means for storing through said inlet opening to
said primary oxidation chamber to form a mass of solid organic
materials in said primary oxidation chamber; means for supplying an
oxidant into said primary oxidation chamber to gasify said solid
organic materials to produce gasified organic materials including a
first gaseous effluent and solid residue, said means for supplying
said oxidant having an air distribution member surrounding said
transfer passages means adjacent to said inlet opening of said
primary oxidation chamber to introduce air into the interior of
said mass of solid organic materials in said primary oxidation
chamber; means provided in said bottom of said primary oxidation
chamber in the middle of the chamber for the removal of said solid
residue of said solid organic materials from said primary oxidation
chamber after said solid organic materials have been gasified;
means disposed within said primary oxidation chamber for
establishing a gaseous flow path within said primary oxidation
chamber for enhancing the oxidation of said mass of solid organic
materials to produce said first gaseous effluent; and means for
removing said first gaseous effluent from said primary oxidation
chamber.
[0019] In accordance with the present invention, an apparatus is
provided for the recovery of energy from biomass materials by the
gasification of such materials.
[0020] The method and apparatus according to the present invention
can be utilized on a cost-effective basis, due to the relatively
low capital cost of the apparatus, to cleanly and efficiently
recover energy at medium rates of recovery, and even at low rates
or recovery, for example, approximately 100,000 BTU/Hr., rates
which typically are those needed in home heating units, and larger
units for commercial applications. The apparatus according to this
invention utilizes a primary oxidation chamber with a converging
upper portion to facilitate even mixing where the biomass feed
stock is partially oxidized slowly in a process in which it first
evaporates the volatiles and moisture and then reacts the resulting
char preferably in a deficiency of oxygen, producing a medium
temperature combustible effluent which can be oxidized in a
secondary oxidation chamber or the partially oxidized combustible
effluent can be use as a fuel for mechanical engines (such as
turbines), or processed to create alternate fuels such as Ethanol
and Methanol. If completely oxidized in the secondary chamber the
high temperature effluent from the secondary oxidation chamber can
be utilized as a thermal energy source, (for example, in an
otherwise conventional water tube boiler as a substitute for the
effluent from the fuel oil or gas burner that is normally utilized
in conjunction with a boiler of such type). During normal
operation, the biomass feedstock is mechanically fed to the primary
oxidation chamber from a storage hopper by means of a single or
multiple screw feeding system, preferably automatically in response
to the demand for fuel from the system. The converging primary
oxidation chamber is provided with a hydraulic or screw conveyor
system for removing ash and non-combustible contaminants, such as
sand, dirt, stones and rocks from the chamber.
[0021] The biomass oxidation method and apparatus according to the
present invention can be utilized to particular advantage in small
and medium sized industry applications and where biomass feed
stocks are plentiful and inexpensive as a result of the
agricultural and/or forest-based business activities that are of
frequently conducted in such regions.
[0022] Accordingly, the present invention provides an improved
method and apparatus for producing energy by gasification of
organic materials.
[0023] More particularly, the present invention provides an
improved method apparatus for efficiently producing energy at
relatively low rates by the gasification of organic materials.
[0024] Suitably the method is a continuous method, wherein the
solid organic materials are transferred to said primary oxidation
chamber to maintain a mass of said solid organic materials in said
primary oxidation chamber, wherein said oxidant is continuously
added to said primary oxidation chamber to continuously gasify
solid organic materials in said mass, and wherein said gasified
solid organic materials are continuously transferred out of said
gasification chamber. Desirably said gasified solid organic
materials are continuously transferred to a device to recover the
thermal energy therein. Suitably the method further comprises the
steps of controlling the rate at which said solid organic materials
are transferred to said primary oxidation chamber to maintain a
substantially constant mass of said solid organic materials in said
primary oxidation chamber. Desirably said oxidant is added to said
primary oxidation chamber at a rate which is insufficient to fully
oxidize said solid organic materials, said method further
comprising the steps of: providing a secondary oxidation chamber
for receiving said gasified solid organic materials that are
transferred out of said primary oxidation chamber; adding an
oxidant to said secondary oxidation chamber to further oxidize said
gasified solid organic materials; and transferring said further
oxidized gasified solid organic materials out of said secondary
oxidation chamber. Suitably the oxidant that is added to the
primary oxidation chamber consists essentially of air or oxygen or
temperature enhanced air. The oxidant added to said secondary
oxidation chamber preferably also consists essentially of ambient
air.
[0025] The method according to the present invention for gasifying
solid organic materials to produce finished gaseous effluent and
solid residue includes the steps of: [0026] a) providing a primary
oxidation chamber having a bottom portion and a converging upper
portion to facilitate mixing of gaseous material in the chamber;
[0027] b) introducing solid organic materials from a source of
supply into the primary oxidation chamber to provide a mass of the
solid organic materials in the primary oxidation chamber; [0028] c)
heating a mass of the solid organic materials in the primary
oxidation chamber; [0029] d) adding an oxidant to the primary
oxidation chamber to gasify the heated mass of solid organic
materials in the primary oxidation chamber and to initiate a flow
of gaseous effluent within the primary oxidation chamber; [0030] e)
establishing a gaseous flow path within a the primary oxidation
chamber whereby a portion of the gaseous effluent flows in an
upward direction through the heated solid organic materials to
enhance continuous oxidation of the organic materials, and
advancing the remaining portion of the gaseous effluent flow in a
direction outward from the primary oxidation chamber; and, [0031]
f) transferring the solid residue out of the primary oxidation
chamber.
[0032] The method may be a continuous or intermittent method. That
is, the solid organic materials may be continuously or
intermittently transferred to a device to recover the thermal
energy therein. Solid organic materials may be transferred to the
primary gasification chamber at a predetermined or at a
controllable rate to maintain a mass, which may be substantially
constant, of solid organic materials in the gasification chamber.
Oxidant is continuously added to the primary oxidation chamber to
continuously gasify the solid organic materials in the mass. Solid
residue is continuously transferred out of the gasification
chamber. The oxidant may however be added to the primary oxidation
chamber at a rate which is insufficient to fully oxidize the solid
organic materials, in which case the method further comprising the
steps of providing a secondary oxidation chamber for receiving the
remaining portion of the gaseous effluent that is transferred out
of the primary oxidation chamber; transferring the effluent to
another process application or adding an oxidant to the secondary
oxidation chamber to further oxidize the remaining portion of the
gaseous effluent into a gaseous finished effluent; and transferring
the finished gaseous effluent out of the secondary oxidation
chamber. The secondary oxidation chamber may be generally
cylindrically shaped, the remaining portion of the gaseous effluent
flowing through the secondary oxidation chamber generally parallel
to a longitudinal axis of the secondary oxidation chamber. The
method may include adding oxidant to the secondary oxidation
chamber substantially tangentially to the secondary oxidation
chamber so as to swirl the oxidant around the remaining portion of
the gaseous effluent that is flowing through the secondary
oxidation chamber.
[0033] In one embodiment, the oxidant that is added to the primary
oxidation chamber consists essentially of ambient, heated or
modified air. The oxidant that is added to the secondary oxidation
chamber may consist essentially of ambient air.
[0034] The solid organic materials may be transferred into the
primary oxidation chamber at a location adjacent the side of the
cylinder or box. Advantageously, the method of the present
invention may also include the steps of: providing an ash removal
system within the primary oxidation chamber at a location in the
lower portion of the cylinder or box, the ash removal system
receiving the solid organic materials as the solid organic
materials are transferred into the primary oxidation chamber; and
maintaining the mass of the solid organic materials on the ash
removal system during the oxidation of the solid organic materials
in the primary oxidation chamber. The method according to the
present invention may further include the steps of: sensing the
elevation of the top of the mass of solid organic materials on the
grate; and controlling the rate at which the solid organic
materials are transferred into the primary oxidation chamber to
maintain the top of the solid organic materials on the grate at a
substantially constant elevation.
[0035] The method of the present invention may further include the
step of periodically actuating the ash removal system to remove the
non-combustible residue from the primary oxidation chamber.
[0036] The primary oxidation chamber may be vertically disposed and
the solid organic materials may be transferred into the primary
oxidation chamber at a location spaced along the either or both
sides thereof. A part of the oxidant may be added to the primary
oxidation chamber at a location adjacent the bottom portion. The
second part of the oxidant may be added to the primary oxidation
chamber above its bottom to gasify the heated organic materials in
stages. The step of advancing the remaining portion of the gaseous
effluent from the primary oxidation chamber may occur through an
insulated exit duct that has a restricted entry portion to prevent
the passage of flame from the primary oxidation chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The present invention will be further illustrated by way of
the accompanying drawings, in which:
[0038] FIG. 1 is an elevation view, partially in section, of an
apparatus for gasifying solid organic materials according to the
present invention.
[0039] FIG. 1b shows an alternate side feed method.
[0040] FIG. 2 is a fragmentary elevation view, in section, of a
portion of the apparatus depicted in FIG. 1 showing the primary
chamber.
[0041] FIG. 3 is a fragmentary elevation view, in section, of a
portion of the apparatus depicted in FIG. 1; Oxidizer.
[0042] FIG. 4 is a more detailed view of the floor and feed
system.
[0043] FIG. 4b shows an alternative feed for the same floor.
[0044] FIG. 5 is a flow diagram showing the process to a heat
exchanger.
[0045] FIG. 6, is a schematic flow diagram illustrating a typical
process,
[0046] FIG. 7 is a plan view of the gasifier of the present
invention illustrating infeed and oxidizer.
[0047] FIG. 8 is a sectional view taken on line 8-8 of FIG. 7.
[0048] FIG. 9 is a sectional view taken on line 9-9 of FIG. 7.
[0049] FIG. 9a is an enlarged view of the gasifier illustrated in
FIG. 9.
[0050] FIG. 10 is an enlarged view of the walking floor.
[0051] FIG. 11 is an enlarged view of the fuel infeed
mechanism.
[0052] FIG. 11a is an enlarged plan view of the compression chute
and diffuser of fuel infeed mechanism.
[0053] FIG. 12 is a sectional view taken on line 12-12 of FIG.
7.
[0054] FIG. 13 is a graph plotting temperature vs. sensor height to
determine height of fuel bed.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0055] As is shown in FIG. 1, an apparatus for practicing the
present invention utilizes a feed assembly, indicated generally by
reference numeral 300, which is driven by a drive assembly and
which feeds material from a storage hopper assembly 100 into a
primary oxidation chamber 400. The inert or unburned portion of the
feed material or fuel fed into primary oxidation chamber 400 is
withdrawn as ash 500 and transported from chamber 400 by an ash
removal system 420. In the preferred embodiment of the invention,
the fuel fed into the primary oxidation chamber 400 is only
partially oxidized therein, and hence there is provided a secondary
oxidation chamber, indicated generally by reference numeral 600, to
complete the oxidation of the partially oxidized gaseous effluent
from chamber 400 after it leaves primary oxidation chamber 400. The
fully oxidized gaseous effluent from secondary oxidation chamber
600 may be used as a source of heat energy in a device or process
which requires heat energy. In the preferred embodiment of the
present invention this may take place between the second
oxidization chamber 600 and the stack 700.
[0056] The material which is to be oxidized is delivered to storage
hopper assembly 100 in any suitable manner, for example, manually
from a pile of such material or by means of a conveyor, not shown,
from a self-unloading truck body of an appropriate type, also not
shown, or in any other suitable manner.
[0057] The feed material which is delivered into the storage hopper
assembly may be any of the wide range of solid, organic materials
of a type which is frequently referred to as "biomass" materials,
and suitable materials of this type include wood chips, sawdust,
corn cobs, and bagasse. These materials are usually waste
by-product materials from various agricultural or forest-based
industrial processes, and contain substantial amounts of chemical
energy that is capable of being converted to thermal energy by
suitable oxidation processes. Such materials are, however,
difficult to handle because they are usually moist and are non
uniform or irregular in shape, and heretofore it has been difficult
to efficiently and effectively oxidize such materials because of
their high moisture content, their non uniform chemical
composition, and their frequent contamination with non-reacting
materials, such as sand, dirt, rocks and stones.
[0058] FIG. 1b shows a different fuel delivery process.
[0059] As noted above, the feed material delivered in direction F
from storage hopper assembly 100 is oxidized to a gaseous state in
the primary oxidation chamber 400, preferably to a state which is
not fully oxidized. The primary oxidation chamber 400 has a chamber
402 which is defined by wall 401 surrounding a vertically extending
cylinder or box. Chamber 402 rests on a floor 403. Box 402 is open
at its top. A downwardly facing hemispherical dome or angled roof
404 is mounted over the open top of chamber 402. Wall 401 has a
multiplicity of layers. The innermost layer 405 is a layer of a
high-temperature refractory material that is capable of
withstanding the elevated temperatures that will develop within the
primary oxidation chamber 400, for example, temperatures in the
range of approximately 2300.degree. F. to approximately
2500.degree. F. Wall 402 is thus capable of allowing the oxidation
of the biomass feed material that is developed in the primary
oxidation chamber 400 while maintaining a tolerable skin
temperature on the outside of the wall. In particular, wall 401 may
include an insulating layer 406 mounted behind the innermost layer
405 to reduce a loss of heat through wall 401. The insulating layer
406 may be a single layer of a suitable insulating material, for
example, insulating brick or insulating fire brick, or it may be
made up of a multiplicity of layers of similar or dissimilar
insulating material if it is desired to minimize the transfer of
heat through the wall 401 to a degree that cannot be accomplished
in a satisfactory manner by means of a single layer of insulating
material, all of which is known in the art. The multiplicity of
layers in wall 401 may advantageously include a structural layer
407 of sheet metal, for example, plate steel, to provide strength
and rigidity for the primary oxidation chamber 400.
[0060] The biomass feed material from the storage hopper assembly
is introduced into the primary oxidation chamber 400 through an
opening 408 in the side of wall 401 or in floor 403 of the primary
oxidation chamber 400. An annular distributor 409 forms part of the
floor 403. Feed material is introduced upwardly through opening 408
and annular distributor 409 by means of a feed assembly 300. During
normal operating conditions, as is illustrated in FIG. 5, the feed
material rises in direction G over the top lip of the annular
distributor 409 and rests on ash 500, until it forms a mass M of
such material. This is the normal equilibrium condition of the
primary oxidation chamber 400 when it is operational.
[0061] To bring the primary oxidation chamber 400 to an operational
condition on start up, the feed assembly 300 is activated to
develop a mass of feed material on the ash removal system 420. The
mass of feed material is then ignited, for example manually or by a
pilot burner. A removable wall portion 401a of wall 401 of is
removable from the remaining portion of wall 401 to facilitate the
igniting of the mass of unlit feed material, and to permit the
inspection and/or cleaning out of chamber 402. The removable
portion 401a may be mounted on a swing-out arm assembly (door) 410
to facilitate the removal of the removable portion 401a of wall
401.
[0062] The oxidation of the feed material in the primary oxidation
chamber 400 requires a source of oxygen. Ambient air has been found
to be a suitable source of oxygen for this purpose. An air blower
411 provides ambient air to the primary oxidation chamber 400.
Blower 411 introduces ambient air in direction H into the interior
of the mass of feed material through annular distributor 409.
[0063] Un-oxidized feed material or fuel 302 is driven by feed
assembly 300 in direction G up into mass M. Feed material 302 moves
from the bottom to the top of mass M, and heats as it moves
upwardly. As it heats, volatile ingredients in fuel 302 begin to
gasify and dissipate. Gasified volatile ingredients are drawn away
by an induction fan or by the natural draw of a stack down-stream
from the gasifier. Air from the blower 411 is forced upwardly
through fuel 302. As fuel 302 in mass M loses more and more of its
volatile ingredients as they gasify, fuel 302 becomes char and
eventually ash. This happens progressively as fuel 302 is exposed
to the full operating temperature inside the primary oxidation
chamber 400 and more air, at which time all of the volatile
ingredients such as the organic constituents of the fuel gasify and
pass in direction I from the primary oxidation chamber 400 as an
incompletely oxidized gaseous effluent E, gaseous effluent E
leaving the primary oxidation chamber 400 through an insulated exit
duct 412.
[0064] The oxidation of fuel 302 in mass M proceeds more
satisfactorily if the amount of feed material in mass M is
maintained at relatively constant. To accomplish this, a reciprocal
probe 414 is mounted in wall 401 so as to extend downwardly into
primary oxidation chamber 400 through wall 401 to determine the
elevation of the top of the feed material in mass M. Suitable
instrumentation, not shown, is provided to control the rate of the
delivery of the feed material into the primary oxidation chamber
400 by the feed assembly 300 as a function of the elevation of the
top of the feed material in mass M, as measured by the reciprocal
probe 414, to maintain a substantially constant elevation of the
top surface of mass M, and thereby to contain the mass of mass M at
the substantially constant value. The reciprocal probe 414 is
preferably internally cooled, by circulating air or water, to
permit it to function satisfactorily in the high temperature
environment of the primary oxidation chamber 400.
[0065] The air which is added to the primary oxidation chamber 400
through the annular distributor 409 appears to flow up through mass
M. This continuous flow of air progressively changes in composition
as fuel 302 is gasified and oxidized so as to include gaseous
oxidized feed material. The hemispherical shape of the dome
facilitates the quality and mixing of effluent E.
[0066] When the gaseous effluent E leaving the primary oxidation
chamber 400 through the insulated exit duct 412 is not being used
for other application, it passes into secondary oxidation chamber
600. Secondary oxidation chamber 600 may advantageously be in the
form of a cylinder having insulated walls 601 and whose
longitudinal axis D is coextensive with the longitudinal axis of
insulated exit duct 412 of the primary oxidation chamber 400. A
secondary oxidant is added to the secondary oxidation chamber 600
to burn or completely oxidize effluent E flowing into the secondary
oxidation chamber through the insulated exit duct 412 from the
primary oxidation chamber 400. Again, ambient air is satisfactory
for use as the secondary oxidant and may be provided to the
secondary oxidation chamber 600 by means of a second blower 602,
again of conventional construction. Preferably the blower 602 is
arranged with its outlet 603 entering the secondary oxidation
chamber 600 in a direction C which is tangential to walls 601.
Sufficient air is added to the secondary oxidation chamber 600 by
means of second blower 602 to fully oxidize the partially oxidized
gaseous materials in effluent E entering the secondary oxidation
chamber 600 from the insulated exit duct 412 of the primary
oxidation chamber 400. Preferably, excess air is forced in to
secondary oxidation chamber 600 to ensure complete reaction and to
prevent excessively high temperatures from developing therein.
[0067] In the preferred operation of the apparatus according to one
embodiment of the present invention, and without intending to be
limiting, the temperature in the secondary oxidation chamber 600
should be limited to approximately 2800.degree. F. This may be
accomplished by utilizing air forced in to the system, including
the air blown in to the primary oxidation chamber 400 by the air
blower 411 and the air blown in to the secondary oxidation chamber
600 by the second blower 602. For example, the total volume and
flow rate of air forced into both chambers 400 and 600 may equal
approximately 150% of that required for full oxidation of the
volume of fuel 302 added to the primary oxidation chamber 400. The
fully oxidized, high-temperature gaseous material from the
secondary oxidation chamber 600 exits from the secondary oxidation
chamber 600 as an effluent B through a second insulated duct 606
and passes into a energy recovery system such as heat exchanger 800
or into an exhaust stack 700.
[0068] Ash removal system 420 is mounted under primary oxidation
chamber 400 and includes a continuous or intermittent operating
auger or hydraulic ram system. Ash removal system 420 may be
mounted as part of floor 403. Feed assembly 300 includes one or
more angled feed augers 321 or hydraulic rams (not shown), fed by
one or more horizontal augers 322 that bring fuel 302 in direction
F to the feed augers 321. An angled and perforated air bed 411
which forms the upper surfaces on distributor 409 allows air
flowing in direction H to mix with the fuel 302 in mass M so as to
form the proper fuel bed. Nonoxidizable materials which were in the
original feed material 302 normally work their way to the bottom of
mass M as ash 500 as the oxidation process continues. Ash 500 exits
from the primary oxidation chamber 400 through the ash removal
system 420 by means of augers 421 mounted below so as to remove ash
falling in direction A through a central aperture 422 formed
between and under the sloped inner surfaces of airbed 411. A
storage hopper assembly or conveyor (not shown) is attached to the
ash removal system 420 for removal of material from the primary
chamber 400.
[0069] While the invention has been described in reference to the
use of the heat produced thereby to heat water in a water tube
boiler or heat exchanger 800, the heat produced by the invention
can also be used in other ways, for example, in the generation of
electricity or the use of the effluent from the primary chamber in
other processes.
[0070] A further embodiment 1000 of the present invention for
gasifying materials such as the organic biomass by-products of
logging and farming industry, is further illustrated within the
accompanying drawings, FIGS. 6 through 12.
[0071] Embodiment 1000, may generally include a storage container
1004, into which solid organic by-products or other biomass fuel
1006 such as wood chips, hog fuel (bark mulch), slaughter-house
waste etc. can be loaded.
[0072] A walking floor 1010 within container 1004 moves such fuel
toward a discharge port 1012. Discharge port 1012 may contain an
agitator 1020 or like mechanism for breaking up compacted fuel.
[0073] Walking floor 1010 has a lower stationary component 1024
containing a plurality of upstanding, transversely positioned fixed
baffles 1028 and a reciprocally movable component 1030 also
containing upstanding baffles 1036 which are positioned
intermediately of the fixed baffles 1028 on stationary component
1024. Reciprocally movable component 1030 is operated by way of
example, a hydraulic ram 1038.
[0074] A fuel delivery mechanism 1040 is positioned below discharge
port 1012 of container 1004. Fuel 1006 falls from agitator 1020
through discharge port 1012 into the fuel delivery mechanism 1040.
Fuel delivery mechanism 1040 is in a preferred form a hydraulic ram
1044.
[0075] Fuel dropping through discharge port 1012 falls into the
breech 1048 of fuel delivery mechanism 1040. Ram 1044 drives fuel
1006 from breech 1044 into a compression tube 1050. Successive
strokes of ram 1044 drive discrete slugs 1054 of fuel into a
diverging chute or diffuser 1058. Both tube 1050 and diffuser 1058
are lined with fireproof refractory material such as heat resistant
brick or concrete. The compacted fuel slugs 1054 within compression
tube 1050 inhibit a fuel back-burn toward fuel storage container
1004.
[0076] Fuel is thus continuously supplied from container 1004 to
primary oxidation chamber 1060. Fuel delivery system 1040 may have
a capability of delivering such fuel to primary oxidation chamber
1060 at 500 lbs/hr. although this is not intended to be
limiting.
[0077] Fuel delivery mechanism 1040 in a preferred form is upwardly
inclined with respect to primary oxidation chamber 1060 so that
fuel discharging from diffuser 1058 is driven upwardly into chamber
1060, forming a mounded fuel bed having a convex upper surface as
illustrated in FIG. 9.
[0078] An oxidant for example in the form of ambient air is
introduced into primary oxidation chamber 1060, generally below the
surface of fuel 1006, through perforated conduits 1070. Blower 1074
provides air at a rate of 944.4 lb/hr although this is not intended
to be limiting.
[0079] Heat sensors 1076 positioned within chamber 1060 may be
coupled to processor means known in the art which regulate both the
volume of fuel and ambient air delivery to chamber 1060 to maintain
the level of the fuel bed and the temperature of the outflow to the
secondary oxidation chamber 1100.
[0080] An ash removal system 1080 is positioned beneath primary
oxidation chamber 1060 and generally comprises a walking floor 1082
and a conveyor 1090. Ash 1086 at a rate of 1.9 lb/hr, although this
is also not intended to be limiting, falling onto floor 1082 is
moved onto a conveyor 1090 for immediate removal and subsequent
disposal.
[0081] A secondary oxidation chamber 1100 positioned downstream and
in fluid communication with primary chamber 1060 receives a high
carbon gaseous effluent from primary chamber 1060. An oxidant which
again may be in the form of ambient air is introduced into chamber
1100 near the upstream end 1100a by blower 1074a at a rate of
5661.6 lb/hr, not intended to be limiting, to produce secondary
oxidation temperatures generally in the range of 2000 Deg.
Fahrenheit, although such temperature is not intended to be
limiting.
[0082] Ambient air is introduced onto secondary oxidation chamber
1100, near downstream end 1000b, by blower 1074b at a rate of 738
lb/hr to thus reduce secondary oxidation temperatures to
approximately 1600 Deg. Fahrenheit. Although, as stated previously,
such rate and temperature are not intended to be limiting.
[0083] An exhaust stack 1104 positioned near the downstream end
1100b of secondary oxidation chamber 1100 further regulates the
internal temperature of air within chamber 1100.
[0084] For example, louvers 1108a and 1108b mounted within chamber
1100 in proximity to exhaust stack 1104 may generally be remotely
operated in accordance with instructions for the processing means
in response to temperature data from heat sensors located, by way
of example, in secondary oxidation chamber 1100 near ends 1100a and
1100b or within a remote facility such as a heat exchanger or dry
kiln 1110.
[0085] Should the temperature sensing mechanism with the heat
exchanger or dry kiln 1110, for example, determine that incoming
heated air is below an optimal temperature, louvers 1108a are
actuated to restrict air flow outwardly of stack 1104 while louvers
1108b are simultaneously actuated to permit a greater volume of
heated air to be discharged from the downstream end 1100b of
secondary oxidation chamber 1100.
[0086] As will be apparent to those skilled in the art in the light
of the foregoing disclosure, many alterations and modifications are
possible in the practice of this invention without departing from
the spirit or scope thereof. Accordingly, the scope of the
invention is to be construed in accordance with the substance
defined by the following claims.
* * * * *