CA2649285A1 - A method for gasifying solid organic materials and apparatus therefor - Google Patents

Abstract

A method for gasifying solid organic materials, a novel apparatus for that purpose, and a system therefor. A unique method and apparatus that produces a high energy, low temperature, 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 containing a predetermined amount of fresh air is utilized for the oxygen content therein and for controlling the method.

Description

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 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 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.

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.

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.

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 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.

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 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 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 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.

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.

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 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 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.

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.

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.

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 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 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 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 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 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.

Claims (62)

1. Apparatus for gasifying organic material, the apparatus comprising:
a gasifier chamber having a floor and an exit port for syngas produced by gasification of the organic material;
a feed device for carrying the organic material upwardly into the gasifier through an opening in the floor to form a heap of organic material on the floor;
a radar device supported adjacent a non-metallic portion of a wall of the gasifier chamber, the radar device oriented to sense a height of a heap of organic material on the floor; and, a controller configured to regulate operation of the feed device to maintain a desired heap height based at least in part on a signal from the radar device.

2. Apparatus according to claim 1 wherein an axis of the radar device intersects the floor non-perpendicularly.

3. Apparatus according to claim 1 or 2 wherein the wall of the gasifier chamber comprises a layer of a high-temperature-resistant refractory material and the radar device senses the heap of organic material through the layer of high-temperature-resistant refractory material.

4. Apparatus according to any one of claims 1 to 3 wherein the radar device is supported on an outside of the gasifier chamber by an angularly-adjustable mount.

5. Apparatus according to any one of claims 1 to 4 wherein the radar device is located above a roof of the gasifier chamber and is oriented to direct a radar beam downwardly toward a heap of organic material on the floor.

6. Apparatus according to any one of claims 1 to 5 comprising a source of oxidative gas connected to supply oxidative gas to a plurality of nozzles located around the opening.

7. Apparatus according to claim 6 wherein the oxidative gas comprises a mixture of air and flue gas.

8. Apparatus according to claim 6 wherein the oxidative gas comprises a mixture of air and steam.

9. Apparatus according to any one of claims 1 to 5 comprising a feed cone above the opening in the floor, the feed cone comprising a passage for allowing the organic material to pass through the feed cone and a sloped outer wall.

10. Apparatus according to claim 9 comprising a source of oxidative gas connected to supply oxidative gas to a plurality of nozzles located on the outer wall of the feed cone.

11. Apparatus according to claim 10 wherein the nozzles comprise tuyeres arranged in a plurality of rows extending around the outer wall of the feed cone.

12. Apparatus according to claim 10 or 11 wherein the oxidative gas comprises a mixture of air and flue gas.

13. Apparatus according to claim 10 or 11 wherein the oxidative gas comprises a mixture of air and steam.

14. Apparatus according to any one of claims 9 to 13 wherein the feed cone comprises a plurality of separate segments.

15. Apparatus according to any one of claims 9 to 14 wherein the feed cone is movably mounted within the gasifier chamber.

16. Apparatus according to claim 15 wherein the feed cone is moveable in a partial circular motion.

17. Apparatus according to claim 15 wherein the feed cone is mounted for oscillation.

18. Apparatus according to any one of claims 9 to 17 wherein the passage tapers from a smaller cross section at a lower end of the passage to a larger cross section at an upper end of the passage.

19. Apparatus according to claim 18 comprising a plurality of tuyeres on a wall of the passage.

20. Apparatus according to any one of claims 1 to 19 comprising an ash dump device provided in the floor of the gasification chamber.

21. Apparatus according to claim 20 wherein the ash dump device comprises:
a first grate ring in a floor of the gasification chamber, the first grate ring having a plurality of openings therethrough;
a second grate ring having a plurality of openings therethrough positioned above the first grate ring and being moveable relative to the first grate ring; and, a plurality of wedge members projecting from an upper surface of the second grate ring, the wedge members having first and second faces, the first faces adjacent to the openings of the second grate rings and being steeper than the second faces;
wherein the second grate ring is movable between a first configuration wherein the openings of the first and second grate rings are aligned and a second configuration wherein the openings of the first and second grate rings are misaligned, and wherein the wedge members are oriented to push the material toward the openings of the first grate ring when the second grate ring is moved from the second configuration toward the first configuration.

22. Apparatus according to claim 21, wherein the openings of the first and second grate rings are square or rectangular in shape.

23. Apparatus according to claim 21 or 22 wherein the first and second grate rings encircle the opening in the floor of the gasifier chamber.

24. Apparatus according to any one of claims 20 to 23 comprising: at least one pair of temperature-sensing probes spaced vertically apart within the gasifier chamber, the probes connected to provide signals to a controller configured to operate the ash dump device.

25. A gasifier according to claim 24 wherein the pair of temperature-sensing probes is one of a plurality of pairs of temperature-sensing probes within the gasifier chamber; each of the pairs of temperature-sensing probes comprises two vertically spaced apart temperature-sensing probes; and the probes of each pair of probes are connected to provide signals to the controller.

26. A gasifier according to claim 24 wherein the controller is configured to cause the ash dumping device to operate to remove non-combustibles from the gasifier chamber when a temperature difference between the probes falls to a first pre-determined value.

27. A gasifier according to claim 24 or 25 wherein the temperature-sensing probes comprise thermocouples.

28. Apparatus according to any one of claims 1 to 27 wherein the gasifier chamber comprises a constriction dividing an interior volume of the gasifier chamber into a lower portion and an upper portion wherein the exit port is in the upper portion.

29. Apparatus according to claim 28 wherein the constriction comprises a ring of refractory material projecting into the gasifier chamber from a wall thereof.

30. Apparatus according to any one of claims 1 to 29 wherein the wall of the gasifier chamber is generally cylindrical.

31. Apparatus according to claim 30 wherein the floor is round and the opening is located at a center of the floor.

32. Apparatus according to any one of claims 1 to 31 in combination with:
an oxidizer;
a conduit connected between the exit port and the oxidizer;
a syngas burner at an upstream end of the conduit; and an oxidant source connected to supply an oxidant to the syngas burner.

33. Apparatus according to claim 32 wherein the oxidant source comprises a combustion air blower.

34. Apparatus according to claim 32 comprising an intake system connected to supply a combustion atmosphere to the gasifier chamber, the intake system comprising an air inlet, a flue gas inlet and a conduit configured to deliver a mixture of air and flue gas to the gasification chamber.

35. A system according to claim 32 wherein the oxidizer comprises a down-draft oxidizer.

36. Apparatus according to any one of claims 1 to 35 in combination with a kiln coupled to receive syngas from the exit port, the kiln comprising a syngas burner.

37. Apparatus according to claim 36 comprising a syngas blower disposed between the exit port and the kiln, the syngas blower sucking syngas from the exit port and discharging syngas to the syngas burner.

38. A method for generating syngas from organic material, the method comprising:
introducing organic material upwardly into a gasifier chamber having a floor and an exit port for syngas produced by gasification of the organic material through an opening in the floor to form a heap of organic material on the floor;
heating and oxidizing the organic material in the presence of an oxidant gas to generate syngas;
monitoring a height of the heap of organic material by directing a radar beam through a non-metallic portion of a wall of the gasifier chamber; and, regulating the introduction of the organic material to maintain a desired heap height based at least in part on the monitored height.

39. A method according to claim 38 wherein the oxidant gas comprises a mixture of air and flue gas.

40. A method according to claim 38 wherein the oxidant gas comprises a mixture of air and steam.

41. A method according to any one of claims 38 to 40 comprising flowing the oxidant gas into the heap through a plurality of nozzles underlying the heap.

42. A method according to claim 41 wherein introducing the organic material upwardly into the gasifier comprises passing the organic material through a passage in a feed cone having a sloped outer wall and the plurality of nozzles comprises a plurality of tuyeres in the sloped outer wall.

43. A method according to claim 42 comprising moving the feed cone while oxidizing the organic material.

44. A method according to claim 43 wherein moving the feed cone comprises oscillating the feed cone.

45. A method according to claim 43 wherein moving the feed cone comprises moving the feed cone in a partially circular motion.

46. A method according to any one of claims 38 to 45 comprising allowing a layer of ash to form under the heap.

47. A method according to claim 46 comprising removing ash of the layer of ash from the gasifier chamber while performing partial oxidation of the organic materials.

48. A method according to claim 47 wherein removing the ash comprises opening a grate under the heap and collecting ash that passes through the grate.

49. A method according to claim 47 or 48 comprising measuring a temperature difference between two different elevations within the heap of organic material and regulating a rate at which ash is removed from the gasifier chamber based on the temperature difference.

50. A method according to claim 47 or 48 comprising measuring the temperature differences between different elevations within the heap at a plurality of locations within the gasifier chamber and regulating a rate at which ash is removed from the gasifier chamber based on an average of the temperature differences.

51. A method according to claim 47 or 48 comprising measuring a temperature difference between two different elevations within the heap of organic material;
wherein removing the ash from the gasifier chamber is performed in response to the temperature difference between the two different elevations having a first predetermined value.

52. A method according to claim 51 comprising continuing to remove ash from the gasifier chamber until the temperature difference reaches a second predetermined value.

53. A method according to any one of claims 38 to 52 comprising flowing the syngas from the exit port of the gasifier chamber to an oxidizer by way of a conduit;
and, in the conduit, at least partially oxidizing the syngas.

54. A method according to claim 53 comprising mixing an oxidant with the syngas at an upstream end portion of the conduit.

55. A method according to claim 54 wherein at least partially oxidizing the syngas comprises igniting the syngas at a syngas burner at the upstream end portion of the conduit.

56. A method according to any one of claims 53 to 55 comprising removing the syngas from the gasifier chamber at a first temperature less than about 600°F.

57. A method according to claim 56 wherein the first temperature is in the range of about 500 °F to about 600 °F.

58. A method according to any one of claims 53 to 57 comprising heating the syngas in the conduit to provide a temperature rise of 600°F or more.

59. A method according to any one of claims 53 to 57 comprising heating the syngas in the conduit to a temperature of 1200°F or more.

60. A method according to any one of claims 53 to 59 comprising delivering the syngas to the oxidizer at a temperature in the range of about 1200°F to 1400 °F.

61. A method according to any one of claims 38 to 60 comprising passing the syngas to a kiln comprising a syngas burner and heating the kiln by burning the syngas in the syngas burner.

62. A method according to claim 61 wherein passing the syngas to the kiln comprises sucking the syngas into a syngas blower and discharging the syngas from the syngas blower to the syngas burner.