Note: Descriptions are shown in the official language in which they were submitted.
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TO WHOM IT MAY CONCERN
Be it known that Robert G. Graham, a resident of the City of Presque Isle,
County
of Presque Isle, State of Michigan, a United States citizen and Dejan Sparica,
a resident
of Canada, a citizen of British Columbia, Canada, have invented a new and
useful
method which is
A METHOD FOR GASIFYING SOLID ORGANIC
MATERIALS AND APPARATUS THEREFOR
for which the following is a specification.
This application claims priority from US Provisional Patent Application
60/801,574 filed May 18, 2006 and US Utility Application 11/801, 030 filed
May 8, 2007.
The invention disclosed and claimed herein deals with a method for.gasifying
solid organic materials, the novel apparatus for that purpose, and a system
therefor. The
instant invention is a unique method and apparatus that produces a high
energy, low
temperature, and low particulate-laden syngas by controlling the oxygen
content in
combustion air used for "starved air" combustion of biomass in a unique
gasifier.
Recirculated flue gas mixed with a predetermined amount of fresh air is
utilized for
providing the oxygen content therein and for controlling the method.
BACKGROUND OF THE INVENTION
More particularly, this invention deals with a method for gasifying biomass
materials, such as forestry and agricultural residues, industrial waste
materials such as
saw mill pulp, paper products, fowl litter, such as chicken litter and turkey
litter, and
hydrocarbon based plastics and the like.
This invention also deals with the apparatus that is used to convert the
chemical
energy into thermal energy or gaseous products, and specifically, syngas, that
is also
called production gas. Syngas is a compressible synthetic combustible gas
containing
very little particulate material. Thus, this invention can also be viewed as a
method of
producing syngas.
It has long been recognized that many industrial and agricultural solid
organic by-
products, such as forestry and agricultural residue, and the like, are a
potential source of
large amounts of chemical energy. The substantial increases in the cost of
traditional
fuels, such as fuel, oil and natural gas, which occurred during the 1970's,
have provided
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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, 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 power boiler and the
recovery boiler in
a pulp or paper mill. However the high capital cost that has heretofore been
associated
with biomass energy recovery systems has precluded their successful use in
small or even
medium size energy recovery systems.
Medium size energy recovery systems are used in conununity centers, schools,
nursing homes, and small industrial and commercial establishments and, to
date, biomass
fuels have not been satisfactorily utilized as fuels in heating systems for
such facilities.
Among the U.S patents that have issued on inventions relating to the recovery
of energy
from wood chips or similar organic materials are for example, U.S. Patent,
5,138,957 that
issued to Morey, et al. on August 18, 1992; U.S. Patent 4,184,436 that issued
to Palm, et
al. January 22, 1980; U.S. Patent 4,312,278 that issued to Smith, et al. on
January 26,
1982; U.S. Patent 4,366,802 that issued to Goodine on January 4, 1983; U.S.
Patent
4,321,877 that issued to Schmidt, et al on March 30, 1982; U.S. Patent
4,430,948 that
issued to Schafer, et al. on February 14, 1984; U.S. Patent 4,593,629 that
issued to
Pedersen, et al. on June 10, 1986; U.S. Patent 4,691,846 that issued to
Cordell, et al. on
September 8, 1987, and U.S. Patent 4,971,599 that issued to Cordell on
November 20,
1990.
However, it is not known that any of the inventions described in these patents
have been successfully adapted to recover biomass energy on a cost-effective
basis in
small and medium size energy recovery systems.
Thus, gasifiers are not new in the art and there are many publications dealing
with
such pieces of equipment and systems in which they are used, but by way of
illustration,
attention can be directed to U.S. Patent 4,691,846 that issued on September 8,
1987 to
Cordell, et al, in which there is described a method and apparatus for
gasifying solid
organic materials in which the system is described in detail with emphasis on
the hopper
and its manner of operation. It should be noted that the gasifier is shown and
described
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as a dome-like structure with a bottom feed mechanism for the solid organic
materials,
and an upper exhaust system to remove the gaseous effluent to a secondary
chamber.
A second disclosure can be found in U.S. 6,120,567 that issued on September
19,
2000 to Cordell, et al in which there is described a method of gasifying solid
organic
materials and in which a similar apparatus and system as is disclosed in the
`846 patent is
set forth. The `567 patent is related to the `846 patent. Again, it should be
emphasized
that the gasifier is shown and described as a dome-like structure having a
bottom feed
and an upper exhaust for the gaseous effluent. '
A typical and general process in the prior art can be found in Canadian patent
2,058,103 that issued on October 14, 1997 in the name of Morey, et al. in
which a bottom
feed, biomass materials, and gasification system is set forth. The system
feeds fuel such
as green and wet woodchips from below, up through a central opening in a
stationary,
perforate fire table that supports the mound-like fuel bed that is formed
thereby. A
plurality of ring-like manifolds below the fire table, and surrounding the
fuel supply tube
are separately provided with air in a controlled manner according to the
demand for the
combustible gas produced.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 A is a schematic of embodiments of this invention utilizing gasifiers
and
methods of this invention showing a portion of the embodiments.
Figure 1 B is a schematic of embodiments of this invention utilizing gasifiers
and
methods of this invention showing additional portions of the embodiments.
Figure 2 is a full front view of a circular gasifier of this invention.
Figure 3 is a cross sectional front view of the gasifier of Figure 2 through
line A-A.
Figure 4 is an enlarged detail of the radar device used in this invention.
Figure 5 is a view in perspective of one configuration of a segmented, round
cone
feed of this invention.
Figure 6 is a view in perspective of one configuration of a segmented, square
cone
feed of this invention.
Figure 5A is a view in perspective of a unitary, round cone feed of this
invention
Figure 6A is a view in perspective of a unitary, square cone feed of this
invention.
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Figure 7 is a cross sectional view of the area designated 28 of Figure 3,
showing
the detail of the moveable cone feed and the bottom tuyeres.
Figure 8 is a full front view of a square or rectangular, loaf gasifier of
this
invention.
Figure 9 is a cross sectional end view of the loaf gasifier of Figure 8,
through
line B-B.
Figure 10A is a cross sectional view showing the detailed construction of the
walls and roof of the gasifier of this invention having an insulation layer.
Figure l OB is a cross sectional view showing another einbodiment of this
invention and the detailed construction of the walls and roof without
insulation and using
air as the insulation.
Figure 11 is an enlarged view of a roof of a loaf gasifier of this invention
showing
two exit ports and how radar is placed thereon.
Figure 12 is a cross sectional view of the roof of Figure 11, showing the
construction of the roof.
Figure 13 is a top view of the ash collection system of the gasifier of Figure
8.
Figure 14 is a side view of a gasifier I of this invention with the sides open
to
show another embodiment of a grate system of this invention.
Figure 15 is a side cross section view of the grates of Figure 14 through line
C-C
of Figure 14.
THE INVENTION
Thus this invention deals with a method for gasifying solid organic materials,
the
apparatus used in such a method, and a system therefor and with specificity,
it deals with,
in one embodiment, a gasifier for gasifying solid organic materials comprising
in
combination a housing, wherein the housing has a lower portion and an upper
portion and
a circular side wall supported by the lower portion and attached to the upper
portion.
There is a roof for the housing, the roof being supported by and integral with
the
circular sidewall. There is at least one opening through the roof for exiting
syngas
effluent and at least one opening for a sensing device and located at, and
connected to,
the roof opening, is a device for removing the syngas from the gasifier.
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Located at, and associated with the sensing device opening, there is at least
one
device for sensing the elevation of any mass of any solid organic material
contained in
the housing, the sensing device being a radar device that is mounted over any
sensing
device opening and surmounts a non-metallic plate that covers the opening.
Located in the lower housing there is at least one opening for supporting a
device
for determining the amount of non-combustible material remaining within the
gasifier,
and located at, and connected to, the lower portion of the housing, and within
the opening
for supporting a device for detennining the amount of non-combustible material
remaining within the gasifier there is at least one device for determining the
amount of
non-combustible material remaining within the gasifier.
Located in the circular wall, there is at least one opening for supporting at
least
one device for providing oxidative gas to the solid organic materials, the
oxidative gas
being recirculated flue gas containing a predetermined portion of fresh air.
Located in,
and connected to the oxidative gas opening is a device for providing an
oxidative gas to
the solid organic materials.
There is a floor for the gasifier located in the lower portion of the
gasifier, the
floor having a top surface and a bottom surface, the floor having at least one
opening
through it to allow for the passage of solid organic material into the
interior of the
gasifier, wherein the top surface of the floor has a retaining wall on the
outside of each of
the floor openings to form a retention basin to retain the solid organic
materials in the
lower portion of the gasifier to fonn a floorless hearth.
There is a device for moving solid organic materials through the floor opening
and into the gasifier in an upwardly motion and a device for providing and
retaining a
cone structure to the underside of the solid orgainic materials.
The gasifier has a device for containing the solid organic materials while
above
the retention basin and at least one opening in the lower portion of the
gasifier to allow
movement of non-combustibles out of the gasifier, along with a device in the
retention
basin for removing non-combustible materials out of the gasifier.
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Finally, there is a control and monitor for the amount of mass of solid
organic
material within the gasifier and a control and monitor for the amount of non-
combustibles
in the gasifier that are inter-related. This type of gasifier is known in the
art as a circular
gasifier.
In another embodiment, the invention deals with a square or rectangular "loaf'
gasifier. Thus, this embodiment deals with a gasifier for gasifying solid
organic materials
comprising a housing, wherein the housing has a lower portion and an upper
portion and
the housing has four side walls supported by the lower portion and attached to
the upper
portion, thus differing from the above-mentioned circular gasifier.
The loaf gasifier has a roof, the roof being supported by and integral with
the four
side walls and the gasifier has at least one opening through a side wall for
exiting syngas
effluent and at least one opening through the roof for a sensing device.
Located at, and connected to the side wall opening, is a device for removing
the
gaseous effluent from the gasifier and located at, and associated with the
sensing device
opening, there is at least one device for sensing the elevation of any mass of
any solid
organic -material contained in the housing, said sensing device being a radar
device that is
mounted over any sensing device opening and that surmounts a non-metallic
plate that
covers the opening.
Located in the lower housing there is at least one opening for supporting a
device
for determining the amount of non-combustible material remaining within the
gasifier
and located at, and connected to the lower portion of the housing, and within
the opening
described just Supra, there is at least one device for determining the amount
of non-
combustible material remaining within the gasifier.
Located in the sidewalls there is at least one opening for supporting at least
one
device for providing oxidative gas to the solid organic materials, the
oxidative gas being
recirculated flue gas containing a predetermined portion of fresh air. Located
in, and
connected to the oxidative gas opening, is a device for providing an oxidative
gas to the
solid organic materials.
There is a floor for the gasifier located in the lower portion of the
gasifier, the
floor having a top surface and a bottom surface. The floor has at least one
opening
through it to allow for the passage of solid organic material into the
interior of the
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gasifier, wherein the top surface of the floor has a retaining wall on the
outside of each of
the floor openings to form a retention basin to retain the solid organic
materials in the
lower portion of the gasifier to form a floorless hearth.
There is a device for moving solid organic materials through the floor opening
and into the gasifier and a device for providing and retaining a cone
structure to the
underside of the solid organic materials.
In addition, there is a device for heating the solid organic materials while
above
the retention basin and at least one opening in the lower portion of the
gasifier to allow
movement of non-combustibles out of the gasifier, along with a device in the
retention
basin for removing non-combustible materials out of the gasifier.
Finally, there is a control and monitor for the amount of mass of solid
organic
material within the gasifier and a control and monitor for the amount of non-
combustibles
in the gasifier that are inter-related.
In another embodiment, the circular gasifier described Supra is modified to
alter
the flow of effluent by providing a constriction in the midsection of the
gasifier. Thus,
there is a gasifier for gasifying solid organic materials comprising a housing
wherein the
housing has a lower portion having a top part and an upper portion having a
bottom part
and the housing has a circular side wall supported by the lower portion and
attached to
the upper portion, wherein the circular side wall has a constricted section
where the top
part of the lower portion and the bottom part of the upper portion meet and
join.
In yet another embodiment of this invention, the loaf gasifier described Supra
is
also modified. Thus, there is a gasifier for gasifying solid organic materials
comprising
a housing wherein the housing has a lower portion with a top part and an upper
portion
with a bottom part and the housing has four side walls supported by the lower
portion and
attached to the upper portion and the side walls have a constricted section
where the top
part of the lower portion and the bottom part of the upper portion meet and
join.
There is still another embodiment of this invention, said embodiment being a
method of gasifying solid organic materials to produce a gaseous effluent and
a solid
residue, the method comprising providing a supply of solid organic material
and
providing a circular gasifier as set forth in this disclosure.
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Thereafter, the solid organic materials are introduced into the gasifier
upwardly
from a lower portion of the gasifier to provide a mass of solid organic
materials in the
gasifier. The solid organic materials arc ignited and then heated in the
gasifier while
providing an oxidative gas to the gasifier, the oxidative gas being
recirculated flue gas
from a flue stack located in a system in which the gasifier is operating and,
the oxidative
gas is flue gas containing a predetermined portion of fresh air.
There is provided an effluent path of flow within the gasifier for a portion
of the
gaseous effluent to migrate, mix, and react through the heated solid organic
materials and
the syngas formed thereby is transferred outwardly from the gasifier and any
non-
combustible solids are transferred out of the gasifier.
A further embodiment of this invention is a method of gasifying solid organic
material to produce a gaseous effluent and a solid residue, said method
comprising
providing a supply of solid organic material and providing a loaf gasifier as
set forth in
this disclosure and introducing the solid organic materials into the gasifier
upwardly from
a lower portion of the gasifier to provide a mass of solid organic materials
in the gasifier.
The solid organic materials are ignited and then heated in the gasifier while
providing an oxidative gas to the gasifier to provide a gaseous effluent,
wherein.the
oxidative gas is recirculated flue gas from a flue stack located in a system
in which the
gasifier is operating and, the oxidative gas is flue gas containing a
predetermined portion
of fresh air.
There is provided an effluent path of flow within the gasifier for a portion
of the
gaseous effluent to migrate, mix, and react through the heated solid organic
materials and
the syngas formed thereby is transferred outwardly from the gasifier and any
non-
combustible solids are transferred out of the gasifier.
It is contemplated within the scope of this invention to provide systems that
utilize each of the various gasifiers disclosed and claimed in this invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Tuming now to Figure 1, there is shown therein a full front view of a circular
gasifier I of this invention having a solid mass feeder 2 and an ash removal
system 4.
Thus, there is shown a gasifier 1 of this invention that is a circular
gasifier that is
equipped with a solid mass feeder 2 (shown in Figure 1), having a collection
bin 5 that is
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connected by auger feed 3 to the bottom 9 (Figure 2) of the gasifier 1. It
should be noted
that the solid mass feeder 2 runs essentially horizontally 7 beneath the
gasifier I and then
tums essentially ninety degrees vertically 8 and thus feeds the gasifier I
from the center
of the bottom 9 of the gasifier 1. The solid mass feeder 2, in the horizontal
run 7 can be
shrouded or it can be an open trough. It is shown as solid mass feed 2 that is
covered by a
shroud 6 enclosing the auger feed 3 (Figure 3).
The solid mass materials are first comminuted or chopped, if it is forestry
product,
so that it will flow and be ignited readily. Generally this chopped material
is best handled
if the pieces are at least 3 inches or less in any dimension. If the solid
mass material is
chicken litter or turkey litter, then chopping is not required.
Figure 2 is an enlarged front view of a circular gasifier of this invention
showing
the gasifier 1, the auger feed 3, the shroud 6, the horizontal run 7 and the
vertical run 8.
The gasifier per se comprises in combination, a housing 10 that has a circular
side wall
11 supported by the lower portion, generally shown as 12, of the housing 10.
The circular
sidewall 11 is attached to the upper portion indicated generally as 13. The
housing 10 is
surmounted by a roof 14, the roof 14 being supported by, and integral with the
circular
sidewall 11.
Shown in Figure 3 is an exit opening 15 through the roof 14 that is used for
exiting syngas from the method of this invention. Also shown is a sensing
device 16 that
is positioned over an opening 17 (shown in Figure 3). The sensing device 16 is
a radar
that is used to monitor the top of the solid mass 18 shown in Figure 3. For
purposes of
illustration, only one such device 16 is shown, but it is within the scope of
this invention
to use more than one such device 16, and it is preferred to use at least three
such devices
16 and more prefenred to use at least 5 such devices 16 on the gasifier as the
height of the
solid mass pile 18 is critical to providing particulate free, quality syngas.
Details of the
construction of the device 16 is shown in 4 and how it may be positioned on
the gasifier I
is shown in Figure 3
The control of pile height is of critical importance for combustion control
and the
release of gaseous combustibles, i.e., the "product gas". The location of feed
cone(s) 25
and vertical auger(s) are designed to provide a pile having a generous depth,
and which
has a generally flat upper periphery. This flat, mesa-like upper surface
extends over 60 to
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70 percent of the floor area, generally filling the lower portion of gasifier
1, and sharply
tapers downward adjacent wall 11. This downward taper, referred to as the
angle of
repose, is dependent upon the type of fuel used. A flat fuel pile is key to
achieving
uniform combustion without bridging. This flat configuration results in a
uniform pile
depth, which in tum results in uniform air pressure within the pile 18, thus
minimizing
channeling of the pile. Maintaining pile depth is very important. About 6
inches or more
of ash is maintained below the actively burning portion of the pile so as to
prevent heat
damage to feed cone 25 and ash removal system 4.
As the feed material in the 18 in gasifier 1 moves to the feed cone 25 to the
center
and top of the mass, it gets hotter and hotter, and volatile components in
such material
and combustion products begin to dissipate from the surface of the pile,
partly being
assisted by the gases that are rising through such material. As the feed
material in the
pile 18 loses more and more of the volatile and pyrolytic ingredients it will
begin to form
high molecular weight carbonaceous derivatives and char until, eventually, it
is exposed
to the full operating temperature inside gasifier 1. Jhis material moves
generally
horizontally outward and then downward toward the outer wall and lower floor
where it
is exposed to further oxidation agents via tuyere arrays 32 and 34 for a more
complete
reaction, at which time all of the organic constituents of such feed material
will gasify
and will pass from gasifier 1 as an incompletely oxidized gaseous effluent of
combustibles (syngas), the effluent leaving gasifier 1 through an insulated
exit duct 52.
The velocity of the effluent above the fuel pile and out the exit duct is kept
low, reducing
particulate carryover.
It is contemplated within the scope of this invention to provide air- modified
flue
gas (oxidative gas), steam modified ambient air or steam modified pure oxygen
to the
burning piles 18 and 71 through the respective tuyeres fitted on the gasifiers
I and 60.
Feed rate into gasifier 1 is monitored and controlled by monitoring and
controlling fuel pile height within gasifier 1. Suitable instrumentation, not
shown, is
provided to control the rate of the delivery of the feed material into
gasifier 1 by the feed
assembly as a function of the elevation of the top of the feed material in the
height of pile
18 to maintain such elevation at a substantially constant value, and thereby
to contain the
pile 18 of feed material at a substantially constant shape
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Turning to Figure 4, there is shown the roof 14 of a circular gasifier 1 upon
which
is niounted a radar device 16. The device 16 is housed in an open housing 21
and
supported by adjustable fasteners 19 and has the capacity to be adjusted
angularly on
swiveled fasteners 20 so that the contour of the solid mass 18 in the interior
of the
gasifier I can be sensed. The device 16, in its housing 21, is mounted over a
non-metallic
plate 22. The plates 22 have to be non-metallic so that the device 16 can beam
into the
interior of the gasifier 1 and sense the top of the solid mass pile 18. It
should be noted
that the opening in the gasifier is only an opening in the metal cladding, and
not an
opening tlirough the firebrick contained in the interior.
As the solid mass pile 18 burns, it creates a certain amount of ash that must
be
removed from the gasifier 1. Therefore, there is at least one trench 24
provided in the
gasifier floor featuring one or more devices for removal of ash and combustion
residues
and for control of the elevation of the "moving bed of ash" hearth. A most
adaptable
device is an auger 26 shown in Figure 3 (end view only). In Figures 2 and 3,
there are
two trenches 24, one on either side of a centrally located feed cone 25 that
will be
described infra. The ash augers 26 in the trenches 24 move the ash towards
points of
discharge 27 suitably located at the end or bottom of the trenches 24. The
trenches 24 are
connected to a bin or a conveyor of suitable design for further disposal of
the ash (see
Figure 1). The connections are standard connections and are not shown herein.
The formation of the ash creates a floorless hearth in the gasifier 1 on which
the
burning solid mass pile 18 is situated_ By intermittent or continuous ash
removal, there is
created a "moving bed of ash" which is essentially the floorless hearth 30 of
this
invention.
Altematively, the control of the "moving bed of ash" level that creates the
hearth
30, and the removal of the ash, can be accomplished by a conveyor or conveyors
moving
across the entire floor, or section thereof, from side to side, or end to end
of the gasifier
as deemed most suitable for the dimensions and shape of the "moving bed of
ash" hearth
30, or alternatively, a set, or sets, of dump grates can be inserted under the
"moving bed
of ash" hearth 30 to facilitate and control removal of the ash.
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Preferred for this invention when forestry products are used as the feed, is a
peppermill grate 40 ash system (see Figure 7 which is a cutaway portion of
Figure 3,
section 80). The peppermill grate 40 is known in the art and consists of a
flat metal plate
39 that is perforated with a multiplicity of holes 41 for allowing the ash to
fall through it.
Over top of the flat plate 39 is a moveable grate 42, that essentially covers
part of the
holes 41 part of the time and allows other of the holes 41 to be open. The
grate 42 is also
perforated with holes 43. As the grate 42 is moved, generally in an
oscillating motion, the
ash is caused to fall through the holes 42 into the retention basins 29 below
and the
augers 26 then move the ash to one end 27 where it is moved out of the
retention bins 29
into a conveyor system (see Figure 1) for transfer away from the gasifier 1.
Another grate system 84 for the invention disclosed herein that is similar to
a
peppermill grate is shown in Figure 14. Figure 14 is a side view of a gasifier
1 of this
invention with the sides open to show the grate system 84. The grate system 84
consists
of two grate rings 85 and 86 (see Figure 15) at the bottom of the gasifier 1.
The bottom
grate 85 is stationary and it has square openings 87 that are approximately 8
inches wide
by 20 inches long. The top grate 86 is moveable, that is, activated by two
(not shown)
hydraulic cylinders that have a stroke maximum of about 8 inches. Because the
grate is
round, this stroke rotates the grate. The top grate 86 also has square
openings 88. The
hydraulic cylinders stroke the top grate 86 such that it aligns the square
openings 87 and
88 and on the back stroke misaligns the openings covering the bottom openings
87.
The top grate 86 has wedge plates 89 mounted on top of it. These plates 89 are
installed in such a way that when the top grate 86 is rotating towards the
openings 88, the
wedge plates 89 push the ash in front of them towards the openings 87 in the
bottom
grate 85. The movement and height of the wedge plates 89 ensure measurable and
constant ash removal from the bottom of the pile, preventing the ash bridging
above the
ash grate openings. As the bottom layer of the ash is discharged, the mixture
of ash and
unburned carbon from the above drops down lower. As the carbon burns, the
process
temperature in the vicinity of the ash discharge thermocouples becomes higher
indicating
that the system has to wait for the next ash dump.
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As the carbon is more and more combusted and disintegrates, the bottom of the
gasifier becomes colder and colder indicating that the ash only is left at the
bottom of the
gasifier and it is time for a new ash dump.
The portion of a segment of a feed cone 25 is shown surmounting the grate 42.
The grate 42 is surmounting the flat plate 39. At one edge 44 of the grate 42,
there is a
pin 45 that attaches the grate 42 to the flat plate 39 and the grate 42
partially swings
around the pin 45 such that the grate 42 moves in an oscillating motion. The
swinging
motion of the grate 42 moves, the ashes that pile on the grate 42 and the flat
table 39 and
the ash falls through holes 41 and 43 into a bin below. Also shown are the
bottom
tuyeres 34.
It is preferred within the scope of this invention to eliminate the
peppenrnill grate
system when the feed material into the gasifier I is soft, easily combustible
materials,
such as chicken litter, turkey litter, or plastics, and the like.
As indicated supra, the gasifier I has a centrally located feed cone 25
arranged
along the centerline of the chamber and protruding above the general elevation
of the
"moving bed of ash" hearth 30. The feed cone 25 is serviced by a single, or
twin set, of
fuel feed augers 31 entering vertically from below.
The feed cone 25 is circular (See Figures 5 and 5A) for the circular gasifier
1
shown in Figures 2 and 3 and the feed cone 25 is square or rectangular (See
Figure 6 and
6A) for the loaf type of gasifier described infra.
It is contemplated within the scope of this invention to have the feed cones
25 be
utilized as one single piece, that is a unitary article, for example those
shown in Figures
5A and 6A, respectively. However, it is preferred that the feed cones 25 be
segmented as
shown in Figures 5 and 6 so that they can more easily be moved into and out of
the
gasifier I for servicing, maintenance aiid repair. The segment.ed feed cones
25 can be
simply set in place adjacent each other, or they can be mortared together, or
glued
together to hold them in place. Obviously, the segmented feed cones 25 shown
in 5A and
6A are those used in the moveable feed cone described infra.
Also contemplated within the scope of this invention is the use of such feed
cones
25 as non-moveable articles when in use in the gasifier. However, preferred
for this
invention are feed cones 25 that are moveable, that is are moveable in a
partial circular
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motion within the gasifier 1, such that they oscillate. (See Figures 5 and 6).
The purpose
for the moveable feed cones 25 is for providing oxidative gases through the
burning solid
mass pile 18 evenly so that creation of gas chaiuiels can be voided. Periodic
movement of
the cone will prevent oxidative gas from burning holes between the gas sources
and the
surface of the pile.
In the gasifier, a partial primary method is one in which the combustion is
carried
out sub-stoichiometrically with the application of an oxidizing agent, which
in this
invention is flue gas mixed with a predetermined portion of fresh air, wherein
the solid
organic materials are transferred continuously or intermittently to the
gasifier I at a
predetermined rate to maintain a mass of solid organic materials in the
gasifier, and
further wherein the oxidant is continuously added to the gasifier I to
continuously gasify
the solid organic materials in the mass, and still further the solid residue
(non-
combustibles) are transferred out of the gasifier. The oxidizing agent is
administered
through a set or sets of suitable ducts connected to nozzles, preferably
tuyeres and
injection points located within, around and between the feed cones 25, and to
a row, or
line of nozzles and/or tuyeres in the surrounding walls of the gasifier 1.
Thus shown in Figure 3 are the upper tuyeres 32, and the lower tuyeres 33, and
the bottom tuyeres 34 in the cone 25, all of which are used to facilitate the
movement of
the air modified flue gas to the gasifier 1 and into the burning solid mass
18. The upper
tuyeres 32 are fed through a common manifold 35 and the lower tuyeres 33 are
also fed
through a common manifold 36. The tuyeres 32 are linked to the manifold 35 by
feed
tubes 37 and the tuyeres 33 are linked to the manifold 36 by feed tubes 38.
As can be observed from Figures 2 and 3, the manifolds 35 and 36 are fed from
a
flue gas return system, generally 48, that consists of a duct 49 and an air
motor 50.The
inlet 51 of the air motor is attached to the system 60 (Figure 1) for
supplying fresh air-
modified flue gas to the air motor 50.
The gasifier I is equipped with an opening 15 for the movement of the syngas
produced by the method. The opening 15 has surmounted on it, a fixture 52 for
allowing
the attachment of components that are used to handle the syngas, which will be
described
infra.
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Located in the lower portion of the housing 10 of the gasifier I is a device
for
determining the amount of non-combustibles within the gasifier 1. Thus probes
53 can
be used to monitor the level of moving ash bed defined by the upper elevation
of the
accumulated ash. As an exaniple of probes 53, there are used thermo elements
in pairs
located one above the other, distanced sufficiently such that the level of the
moving ash
bed will be in between them, and capable of characterization by the difference
in
temperatures and the temperature of the material above the moving ash bed
while in
operation. Said temperature difference will thenbe the offset that will
dictate the degree
of auger 26 movement required to control the level of the moving ash bed
between the
probes. In this representation, it is assumed that gasifier I is equipped with
several sets
of probes 53, inserted through openings 55, around the perimeter of the
chamber and an
average of probe 53 input data will determine the auger 26 movements.
The floor 57 for the gasifier is located in the lower portion 12 of the
gasifier 1, the
floor 57 having a top surface and a bottom surface. The floor 57 has at least
one opening
through it to allow for the passage of the solid organic material into the
interior of the
gasifier 1.
To bring gasifier I to an operational condition on start up, the feed assembly
3 is
activated to form the pile 18 of feed material in the gasifier I in
preparation of
development of a "moving ash bed" above bottom 9. The pile 18 of feed material
is
ignited. To facilitate bringing the pile 18 of feed material up to its normal
operating
temperature, fuel oil or other readily combustible supplemental fuel may be
added to it.
As an example, this may be done manually through an opening 54 provided in the
wall of
the gasifier 1.
As the oxidation proceeds and the temperatures elevate the solid mass 18 will
pyrolyze and gasify. Gas produced in the starved combustion sifts through the
burning
pile and into the upper portion of the burning pile 18, the upper pile 18
acting as a filter
for particulate material. It is important to conduct the combustion of the
solid mass
below the pile 18. The products of combustion rise through the pile 18 and
cools because
the latent heat of water absorbs the energy. As fuel comes, it gets pyrolyzed
and the fuel
moisture and volatile hydrocarbons get separated from the non-volatile
components.
CA 02649285 2008-10-14
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These processes are driven by the hot gases that result from the combustion of
the fixed
carbon, which takes place below the pile 18.
The moderately slow burning lower portion of the pile will serve to establish
a
quiet oxidation zone whereby entrainment of particulate matter and fly ash is
minimized.
Syngas with a maximum of combustible gaseous components and a minimum of
particulate matter is one key objective of this invention.
Turning now to Figure 8, which is a full front view of a loaf type of gasifier
60,
and Figure 9 that is a full cross sectional view of a gasifier 60 of Figure 8
through line 13-
B, the gasifier 60 is defined by four vertical side walls 61, giving the
chamber a square or
rectangular cross section and forming an enclosure 62 (Figure 9) which has an
irregularly
shaped bottom 63 and which has at its top a roof 64, which in cross section
may be
vaulted, tapered or flat or any combination hereof.
Wa1161 is made up of a multiplicity of layers. In the preferred embodiment,
Figure 10A, the innermost layer 65 is an insulating layer of a high-
temperature resistant
type refractory that is capable of withstanding the elevated temperatures that
will develop
within gasifier 60, for example, temperatures in the range of approximately
2300 F to
approximately 2500 F, and that is capable of withstanding the operational
temperature
variations as well as the corrosive, erosive effects of the gaseous materials
produced by
the oxidation of the biomass feed material that is delivered into gasifier 60.
Wall 6 1 may
also include an insulating layer 66 on the outside of the wall layer 65 to
further prevent
loss of heat through the wall 61 of gasifier 60. As an example, the insulating
layer 66
may be a single layer of insulating firebrick, block insulation, or blanket
insulation. The
outer casing of the wall 61 is a structural layer or shell 67 of sheet metal,
for example,
plate steel, which is airtight and provides the necessary strength and
rigidity for the wall.
A second embodiment of wall 61 is shown in Figure l OB, wherein insulating
layer 66 is not used, and a vacant layer or space 58 is provided between
refractory
innermost layer 65 and steel she1167. The air which fills vacant layer 68 acts
as an
insulator between refractory layer 65 and steel shell 67. This warmed air can
also be
used as a source of preheated air for injection into gasifier 60 and recovery
and
regeneration equipment 96 and 98.
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With further regard to Figures 8 and 9, the biomass feed material from the
storage
hopper assembly (not shown) is introduced into gasifier 60 from below gasifier
60
through at least one feed cone 59 located along the centerline of bottom 63 of
gasifier 60.
During nomlal operating conditions, the feed material rises over the top of
the feed
cone(s) 59 and rests on the hearth 70. Hearth 70 is made up of ash and other
solid
combustion residues, until it forms a pile 71 of such material, which is the
normal or
equilibrium condition of gasifier 60. This self-generated hearth 70 is the
"moving ash
bed" configuration, that is an essential part of this invention and which is
described Supra
with regard to gasifier 1. As primary oxidation progresses, this bed continues
to elevate
and the ash must be removed at essentially the same rate it is formed to
maintain the
appropriate fuel pile height.
As in the gasifier 1 described Supra, the control of pile height is of
importance for
combustion control and the release of gaseous combustibles. The principles
discussed
Supra for the gasifier 1 apply equally well for the gasifier 60 and will not
be repeated
herein.
Returning to Figures 8 and 9, there are shown exit ducts 69 and they are
positioned so that it vents gasifier 60 through roof 64. It should be noted
that prior art
loaf gasifiers required that the exit for the produced gases must be through
the sidewall so
as to minimize the flow of particulate materials along with the gas.
Preferably, sidewalls
61 are provided in a height which allows any air-borne particulate to fall
back to pile 71
rather that exit via duct 69. The positioning of exit duct 69 within gasifier
60 can be as
shown in Figures 8 or 9, and may be sloped or vertical, and is selected to be
practical and
suitable for the specific application.
As in the gasifier 1, Supra, the oxidizing agent is administered through a set
or
sets of suitable ducts connected to nozzles, preferably tuyeres and injection
points located
within, around and between the feed cones 59, and to a row, or line of nozzles
and/or
tuyeres in the surrounding walls of the gasifier I.
Thus shown in Figures 8 and 9 are the upper tuyeres 73, and the lower tuyeres
74,
and the bottom tuyeres 75 in the cone 59, all of which are used to facilitate
the movement
of the air modified flue gas to the gasifier 60 and into the burning solid
mass 71. The
upper tuyeres 73 are fed through a common manifold 76 and the lower tuyeres 74
are also
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fed through a common manifold 77. The tuyeres 73 are linked to the manifold 76
by feed
tubes 78 and the tuyeres 74 are linked to the manifold 77 by feed tubes 79.
Just as in the
tuyeres of the gasifier 1, the tuyeres of the instant invention are either on
or off, and are
not adjustable.
The modified flue gas return system useful in gasifier 60 shown in Figures 8
and
9 can also be observed in Figure 2, and this system is adaptable and useful in
the gasifier
60. The manifolds 76 and 77 of Figures 8 and 9 are fed from a flue gas return
system as
shown in Figure 8, generally 48, that consists of a duct 49 and a fresh air
motor 50. The
inlet 51 of the air motor is attached to the system 60 (Figure 1) for
supplying fresh air-
modified flue gas to the air motor 50. The details of the movement of the
fresh air
modified flue gas from the flue stack to the gasifier is set forth in detail
infra.
It should be noted that the upper part of the lower portion 12 and the lower
part of
the upper portion 13 of the gasifier (Figure 3) are modified from prior art
devices in that,
there is a constriction 80 of the interior of the gasifier 60. This
constriction 80 is built into
the firewall brick 65, or it can be formed from a plate that is set at an
angle into the
firebrick 65. The purpose of this constriction 80 is to slow down the product
gas in its
flow upward which results in another method by which particulate material does
not tend
to reach the exits ports 69.
Feed rate into gasifier 60 is monitored and controlled by monitoring and
controlling fuel pile height within gasifier 60 using the same radar devices
16-as set forth
Supra. Suitable instrumentation, not shown, is provided to control the rate of
the delivery
of the feed material into gasifier 60 by the feed assembly as a function of
the elevation of
the top of the feed material in the height of pile 71 to maintain such
elevation at a
substantially constant 'value, and thereby to contain the pile 71 of feed
material at a
substantially constant size.
Tuming now to Figure 11, there is shown an enlarged view of roof 64 for the
loaf
gasifier 60, that shows the two exit ports 69 for syngas located on the roof
64. Also
shown is a placement of a radar device 16 on the roof 64, between the two exit
ports 69.
The dotted lines 84 illustrate the beam of the radar 16 into the interior of
the gasifier 1.
Figure 12 shows the roof 64 and the construction of the walls of the roof 64.
There is thus
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shown the outside, or steel wall 67, the insulating layer 66 and the interior
firebrick wall
65. The component 82 is a flange that is useful for fitting the roof to the
sidewalls of the
gasifier 60.
Figure 13 is a cross sectional view of the specifics of the ash handling
system of
the loaf gasifier as shown in Figure 8. There is shown the ash handling system
81 that
includes the removable peppermill grates 42, the increasing flight ash augers
in the
collection bin and retention bin 29, and the castable tuyere panels 83. Also
shown is the
exit of the centered feed cone 59.
Turning now to Figures 1 A and I B and a description of a "system" of this
invention, there is shown a schematic of a gasifier I of this invention and
its
interconnection to the various components that can make up the system wherein
the
numbers in pentagons are the flow paths and various components of the system
as
describe infra.
Thus, shown in Figures lA and 1B is a gasifier I that is fed a solid mass
material
2 using an auger feed 3_ Shown also is an ash removal system 4. Syngas 90 that
is
produced by the pyrolysis and gasification of the solid mass material 2 exits
the gasifier-1
through exit port 15 and into a syngas burner'91 and into a syngas blower 92.
The syngas
90 is controlled by draft controls 93. The syngas burner 91 is aided in
combustion using a
combustion air blower 94 that provides air 95 to the syngas burner 91.
The syngas 90 is provided to the syngas burner 91 at a temperature of about
500 F
to about 600 F and is in a starved air condition. This part of the system is
unique to this
type of gasifier system in that the normal temperature of the air from prior
art devices is
in the range of 1200 F to 1400 F, and in prior art systems, this air is not
"starved air", and
before the prior art air can be used, it has to be cooled and compressed,
which means that
additional and expensive equipment has to be added to the system in prior art
processes.
The syngas burner 91 heats and combusts the syngas 90 up to a temperature in
the range
of 1200 F to 1400 F before the heated air 97 is provided to a low NOx oxidizer
96.
In a further embodiment, the syngas 90 can be provided to a kiln 98 using a
syngas blower 99 that moves the syngas 90 to a nozzle mix syngas bumer 100.
Thereafter
the syngas 90 is moved through the nozzle mix syngas burner 100 into the kiln
98. The
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heated air (about 2200 F) from the kiln 98 is moved to the low NOx oxidizer 96
and
combined with the starved air coming from the syngas burner 91.
The heating and movement of the heated air in the kiln 98 is aided by passing
heated air 101 from a heat exchanger 102 (see Figure 1B) and also mixing the
heated air
103 with heated ambient air 105 being bleed into the nozzle mix syngas burner
100 using
a preheated combustion air blower 104, along with additional heated air 101
from the
heat exchanger 102 that is bled 106 directly into the kiln 98.
The heated air 107 from the kiln 98 is fed into the low NOX oxidizer 96 and
mixed
therein with the air 97 being fed into the top portion of the low NOx oxidizer
96. The low
NO,, oxidizer 96 is fed ambient air 108 using a combustion/tempering air fan
109,
through manifolds 110 and tuyeres (not shown) and the air 111 that exits the
low NOx
oxidizer 96 does so at about 2000 F and passes to the heat exchanger 102 shown
in
Figure 1 B.
Turning now to Figure 1 B, there is shown the heat exchanger 102 into which
the
heated air 111 has been passed and the exchanged air 112 is then passed to a
metal heat
exchanger 113 at about 1400 F, the metal heat exchanger 113 being useable
because of
the lower temperature of the air 112. Air 114 is moved to the heat exchanger
102 and the
heated air is that used in the heat exchanger 102 for the exchange. The
movement of the
air 114 is aided by the introduction of fresh air 124 using an air blower 125.
Exchanged air having a temperature in the range of about 400 F to 1200 F is
the
air 101 that is passed back to the kiln 98. The air 101 has to be occasionally
vented in
order to control the tempemture and pressure of the air 101 and this is shown
at 116.
The heat-exchanged air 127 from the metal heat exchanger 113 is moved to an
induction draft fan 115 before it enters the stack 117. Prior to air exiting
122 the flue
stack 117, a portion of the flue gas 120 is withdrawn from the stack 117 and
moved to a
flue gas eductor 118, which is aided by a an induced draft fan 119. At this
point, fresh air
128 is inducted and mixed with the flue gas 120 and it is this flue gas
modified with fresh
air 121 that is moved back to the gasifier 1 as the oxidative gas for use in
the gasifier 1.
Also shown in Figure 1 B is a sampling port 129.
