Gasification apparatus

A gasification system having a combustor vessel, an optional scrubber vessel, an optional fixer vessel, an optional cyclone vessel and an optional demister vessel. A wide variety of possibly moist solid or semi-solid carbonaceous fuels may be partially combusted in the combustor to generate a combustible gas and a mineral ash. An improved ash support and removal subsystem reduces clogging and other problems. The combustible gas is conveyed by optional heavy-duty blowers through the optional vessels to remove liquids and particulates and to undergo catalytic chemical reactions to provide a relatively clean, dry, highly-combustible hydrocarbon gas that captures a relatively high fraction of the potential heating value of the fuel. Internal gases, liquids and particulates from the vessels may be recycled inside the system to improve efficiency and prevent liquid waste. A portion of the internal liquids may also be extracted for other uses.

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gasification apparatus that produces combustible fuel gases from a wide variety of carbonaceous fuel sources or combinations of fuel sources.

2. Brief Description of the Related Art

Gasification has generally been known for years. In gasification, a carbonaceous fuel source is partially combusted to produce a combustible gas, synthesis gas, or syngas. The combustible gas is then combusted to produce work. The combustible gases produced by gasification may find a variety of uses, including, but not limited to, supplying heat, powering a motor, or producing electricity. Gasification provides many advantages, such as allowing fuels having relatively low heating values to be used, allowing waste products to be used to produce work and, similarly, reducing the amount of waste material sent to landfills. Despite these obvious advantages, gasification has met with only limited success, because gasification systems have typically been plagued by a number of disadvantages or difficulties. For example, the heating values of gases produced using prior art systems have tended to fluctuate to an undesirable degree, particularly when a variety of fuel sources or fuel sources of varying compositions have been used. Similarly, it has also proven difficult to consistently produce gases having sufficiently high heating values. Separating particulate matter from the produced gas has proven problematic. Similarly, it has proven difficult to produce sufficiently clean gases having sufficiently low amounts of particulate matter as well as sufficiently low amounts of pollutants such as such as sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOC), ammonia (NH3), hydrogen chloride (HCl) and other chlorides. Environmentally sound disposal of wastewater generated by such systems has also presented difficulties. Further still, the presence of water or other liquids in the combustible gas has made it difficult or impossible to use blowers for moving the combustible gases without creating undesirable levels of wear and tear on the blowers.

BRIEF SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a flexible gasification apparatus that provides combustible gases having high heating values while avoiding pitfalls of prior attempts at gasification.

It is a further object of the present invention to provide an apparatus of the above type that can easily handle a wide variety of carbonaceous fuel sources or combinations of fuel sources.

It is a further object of the present invention to provide an apparatus of the above type that produces a high value heating gas having low amounts of particulate matter and other pollutants.

It is a further object of the present invention to provide an apparatus of the above type that requires little or no wastewater disposal.

It is a still further object of the present invention to provide an apparatus of the above type that captures a relatively high fraction of the potential heating value of the fuel sources.

It is a still further object of the present invention to provide an apparatus of the above type that safely and cleanly consumes a wide variety of agricultural and industrial byproducts, including, but not limited to, animal waste and wood pulp sludge.

It is a still further object of the present invention to provide an apparatus of the above type that is less prone to clogging problems typically associated with ash removal.

It is a still further object of the present invention to provide an apparatus of the above type that may easily process a wide variety of combinations of solid, semi-solid and liquid fuels.

It is a still further object of the present invention to provide an apparatus of the above type that can safely and efficiently handle and dry relatively wet combustible gases.

It is a still further object of the present invention to provide an apparatus of the above type that uses one or more rugged blowers that can safely and efficiently handle both dry and relatively wet combustible gases.

Toward the fulfillment of these and other objects and advantages, the system of the present invention comprises a combustor vessel, an optional scrubber vessel, an optional fixer vessel, an optional cyclone vessel, an optional demister vessel and one or more optional blowers. A carbonaceous fuel is partially combusted in the combustor to generate a combustible gas. An improved ash support and removal subsystem reduces clogging and other problems in the combustor. The combustible gas passes through one or more optional blowers to the scrubber. The combustible gas passes through the scrubber to remove matter such as tar and oil and to undergo preliminary catalytic chemical reactions. The scrubbed gas passes through one or more optional blowers to the fixer. Additional catalytic chemical reactions occur in the fixer and wood chips or other filters may also be used in the fixer to provide a relatively clean, dry, combustible gas. The combustible gas passes through one or more optional blowers to the cyclone, which helps separate additional liquids from the gas. The combustible gas then passes through one or more optional blowers to the demister, which allows additional catalytic reactions to occur and separates additional liquids from the gas. Wastewater, condensate, and other waste products from the scrubber, fixer, cyclone and demister may be captured and returned to the combustor or extracted.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIGS. 1 and 5, the reference numerals10and200refer in general to a gasification system for practicing the present invention. The system10,200typically comprises a combustor12, an optional scrubber14, an optional fixer16, an optional cyclone203and an optional demister204, with one or more optional blowers between these vessels. One or more optional blowers may also be disposed before the first vessel in the system10,200sequence. One or more optional blowers may also be disposed after the last vessel in the system10,200sequence. The system10,200principally consists of preferably the combustor12and the fixer16, more preferably the combustor12, the scrubber14and the fixer16, more preferably the combustor12, the scrubber14, the fixer16and the cyclone203, and most preferably the combustor12, the scrubber14, the fixer16, the cyclone203and the demister204. The combustor12, the scrubber14, the fixer16, the cyclone203and the demister204may comprise any type of reaction vessel. In the system10,200, after the combustor12, the typical and preferable sequence of vessels, the scrubber14, the fixer16, the cyclone203and the demister204, may also be arranged in different sequences.

Referring toFIG. 1, the fuel conduit24is disposed to provide a carbonaceous fuel source into an upper portion of combustor12. The fuel conduit24comprises preferably a conveyor, more preferably an auger drive, suitable for the transfer of solid and semi-solid material. The fuel conduit24transfers the solid or semi-solid carbonaceous fuel into an upper portion of combustor12.

Referring toFIG. 2, the combustor12has an upper outer wall portion20and a lower base portion22. The combustor12is preferably open, more preferably closed at the top and is preferably configured as a downdraft combustor, more preferably as an updraft combustor. The fuel conduit24transfers the solid or semi-solid carbonaceous fuel into an upper portion of combustor12, preferably into an upper portion of the inner chamber30, more preferably into an upper portion of the inner chamber30above the fuel level sensor68. Another feed conduit26may also be provided to recycle material into the combustor12from other portions of the system10,200as discussed in more detail below. Additional feed conduits may also be used, for example, to provide different types of solid, semi-solid and liquid fuel sources. The inner wall28is disposed within the combustor12and is connected to the combustor12to form the inner chamber30and the outer chamber32. A lower portion of the inner wall28defines the opening34. The ash support member36is affixed below the inner wall28, preferably by support members38, more preferably by affixing portions of the outer periphery of the ash support member36to the upper outer wall portion20, so that the ash support member36is disposed a distance below the opening34. The outer periphery of the ash support member36is relatively free from obstructions about the vast majority of the outer periphery, providing relatively open side passageways between the inner wall28and the ash support member36. This allows ash to spill from the ash support member36preferably over at least approximately 80 percent of the outer periphery of the ash support member36, more preferably over at least approximately 90 percent of the outer periphery of the ash support member36and most preferably over at least approximately 95 percent of the outer periphery of the ash support member36.

A conduit or gas manifold46extends preferably through the upper outer wall portion20, more preferably through the lower outer wall portion22, of the combustor12, below the ash support member36. The conduit or gas manifold46is connected to an air source and is preferably connected to an auxiliary fuel source, such as a source of natural gas, liquefied petroleum gas (LPG or LP gas), or propane (C3H8). As seen inFIGS. 1 and 5, a recycle conduit48may also be provided to return a portion of the combustible gas generated by the system10,200. The igniter50, such as a spark plug igniter, is preferably disposed in the conduit or gas manifold46adjacent to the combustor12. As depicted inFIG. 5, the most preferably sequence of attachments along the external portion of the conduit or gas manifold46is to have the recycle conduit48attachment disposed closest to the combustor12, the igniter50disposed further from the combustor12, the auxiliary fuel conduit126disposed an additional further distance from the combustor12and the auxiliary air conduit124disposed the furthest distance from the combustor12.

As seen inFIG. 2, one or more fuel agitators such as the fuel stirring member52are preferably provided in the inner chamber30, preferably disposed above the opening34. Similarly, one or more combustion bed agitators such as the combustion bed stirrer54are preferably provided inside the combustor12, preferably below the opening34and above the ash support member36. One or more ash agitators such as ash stirring member55are preferably provided inside the combustor12, preferably below the ash support member36, more preferably below both the ash support member36and the conduit or gas manifold46. Coaxial shafts56and58extend upward from the stirring members52,54and55to or above an upper portion of the combustor12. Motors60and62are operably connected to the shafts56and58for rotating the shafts and stirring members52,54and55.

Hollow shaft58is rotated by motor60and is preferably connected to both stirring members52and54, more preferably connected to stirring member52but not to stirring member54. Solid shaft56is rotated by motor62and is preferably connected to stirring member55but not to stirring member54, more preferably connected to both stirring member54and stirring member55. Most preferably, motor60is disposed near the top of combustor12and rotates a solid shaft replacement for hollow shaft58which is operably connected to one or more stirring members52, while motor62is disposed near the bottom of combustor12and rotates a separate solid shaft that is operably connected to stirring members54and55.

The preferably frustoconical, more preferably cylindrical, lower base portion22of the combustor12extends below the ash support member36. An opening is provided at or near the bottom of the lower base portion22to allow ash to pass from the combustor12to the ash removal conduit64. The ash removal conduit64preferably comprises an auger drive suitable for solids transfer. A conduit66is disposed through the outer wall of the combustor12in an upper portion of preferably the outer chamber32, more preferably the inner chamber30, to provide a path for combustible gases generated within the combustor12to pass from the combustor12.

A fuel level sensor68is provided in the inner chamber30, preferably above the opening34, more preferably above both the opening34and the fuel agitator52. The fuel level sensor68is operably coupled with the fuel conduit24to automate the process of maintaining fuel at a desired level within the inner chamber30. Additionally, an optional screen is preferably disposed inside an upper portion of the inner chamber30, between the fuel conduit24and the conduit66. The optional ash level sensor70is disposed within the combustor12, preferably below the ash support member36, more preferably below both the ash support member36and the conduit or gas manifold46. The optional ash level sensor70is operably coupled with the ash removal conduit64to automate the process of maintaining ash at a desired level within the combustor12. Additional optional conduits are preferably provided for extracting gas from combustor12for testing and other uses. Additional optional conduits are also preferably provided for extracting liquids from the combustor12for testing and other uses. It is understood that the combustor12may take any number of sizes, shapes and configurations. It is also understood that the combustor12need not be closed at the top and need not be an updraft combustor.

Referring toFIGS. 1 and 5, the conduit66operably couples the combustor12with the scrubber14, providing a flow path through preferably one or more of the optional blowers90into preferably an upper portion, more preferably a lower portion of the scrubber14. As seen inFIG. 3, the blowers90are heavy duty hybrids that combine desirable features of blowers designed for moving gases and pumps designed for moving liquids. The blowers90move gases and/or liquids from an inlet209to an outlet210. Walls forming the impeller housing92have a wall thickness of preferably approximately ¾ inch (2 centimeters), more preferably approximately ⅝ inch (1.6 centimeters). A sealing member94, such as a gasket, is used to create an airtight and watertight seal between the walls forming the impeller housing92. Referring toFIG. 4, the impeller blades96are preferably straight, more preferably curved, and are thicker than impeller blades of common blowers designed for moving gases, preferably approximately 50 percent thicker. Referring back toFIG. 3, the mechanical seal98, similar to a mechanical seal used in a typical centrifugal compressor, is used to provide the impeller shaft100seal. Although not preferred, one or more packing glands similar to those found in a typical water pump may be used as substitutes for the mechanical seal98. Additional sets of the bearings102are also preferably used in connection with the impeller shaft100. It is preferable to use at least two sets of the bearings102. It is understood that the blowers90may be disposed at any number of locations in the system10,200and that the blowers90may take any number of different sizes, shapes and configurations. It is also understood that, although not preferred, conventional blowers, pumps, centrifugal compressors or similar devices may be used as substitutes for the blowers90.

Referring toFIGS. 1 and 5, the scrubber14preferably contains one or more filters (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other filter known to those skilled in the art). The scrubber14more preferably contains one or more filters and one or more catalysts (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other catalyst known to those skilled in the art). Most preferably, the scrubber14contains catalyst material whose surface has properties of stainless steel. Without limiting the present invention thereto, 304, 304H and 316 types of stainless steel have been found to be effective in the practice of the invention. It is hypothesized that the presence of manganese (Mn) in the stainless steel may be significant in promoting the formation of C4and higher hydrocarbons and other high heating value compounds. Non-stainless steel, such as mild steel, cold-rolled steel, hot-rolled steel and chrome steel have been found to have poor performance as compared to stainless steel catalysts. Aluminum has been found to be less effective than non-stainless steel and brass to be less effective than aluminum. The catalysts used in the present invention may be of various shapes and sizes and could include other materials, such as ceramic beads, plated with stainless steel.

Referring toFIG. 1, an optional pump72is preferably provided to pass liquid, for example water with impurities therein, through a feed conduit74into a preferably lower portion, more preferably upper portion, of the scrubber14and preferably through sprayers. A liquid return conduit76is preferably connected to a lower portion of the scrubber14for returning liquid to the optional pump72for reuse within the scrubber14. A feed conduit78may also be provided for providing preferably gas from combustor12, more preferably gas and liquids from combustor12, most preferably gas and liquids from combustor12and recirculated liquid to scrubber14. Optional wash conduit80may be provided for intermittent use to transfer liquid through conduits66,82and104for cleaning. Scrubbed gas exits through conduit82that is disposed at a preferably lower, more preferably upper portion of the scrubber14. Additional optional conduits are preferably provided for passing the scrubbed combustible gas to flare, to recycle, for testing and for further uses. Additional optional conduits are also preferably provided for extracting liquids from the scrubber14or returning liquids from the scrubber14to the combustor12for recycling. An optional skim conduit84is preferably provided at a lower portion of the scrubber14and a drain conduit86is provided at the bottom of the scrubber14. An optional level sensor88, such as a float switch, is preferably disposed in the scrubber14for maintaining liquid levels within the scrubber14at desired levels. It is understood that the scrubber14may take any number of shapes, sizes and configurations and that any number of different filter media or catalysts or different combinations of filter media and catalysts may be used in the scrubber14.

Referring toFIG. 1, the conduit104connects the scrubber14with the fixer16, providing a flow path through one or more optional blowers90into preferably an upper portion, more preferably a lower portion of the fixer16. The fixer16preferably contains one or more filters (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other filter known to those skilled in the art). The fixer16more preferably contains one or more filters and one or more catalysts (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other catalyst known to those skilled in the art). Most preferably, the fixer16contains catalyst material whose surface has properties of stainless steel as described above. The conduit106passes from preferably a lower portion, more preferably an upper portion, of the fixer16to provide a flow path for the scrubbed and fixed combustible gas. The conduits108,48and110are preferably provided for passing the scrubbed and fixed combustible gas to flare, to recycle, for testing and for further uses. Additional optional conduits are also preferably provided for extracting liquids from the fixer16and returning liquids from the fixer16to the combustor12for recycling. An optional skim conduit is preferably provided at a lower portion of the fixer16. The drain conduit112passes from a lower portion of the fixer16for removing wastewater and other matter that condenses or is removed from the gas as it passes through the fixer16. An optional level sensor, such as a float switch, is preferably disposed in the fixer16for maintaining liquid levels within the fixer16at desired levels. It is understood that the fixer16may take any number of shapes, sizes and configurations and that any number of different filter media or catalysts or different combinations of filter media and catalysts may be used in fixer16.

Referring toFIG. 1, the conduits84,86and112preferably provide a flow path from the scrubber14and fixer16into the conduit114, which leads into the pump118. Referring toFIG. 5, the conduits86,112,205,207and208provide a flow path from the scrubber14, the fixer16, the cyclone203and the demister204into the conduit114which leads to pump118. Referring toFIGS. 1 and 5, conduit26preferably operably couples the pump118with the combustor12. It is understood that the pump118may be disposed at any number of locations in the system10,200and that the pump118may take any number of different sizes, shapes and configurations. Liquids may be extracted from conduit114, conduit26and other conduits for testing or use in petrochemical, chemical or other applications.

Referring toFIG. 5, the conduit110operably couples the fixer16with the cyclone203, providing a flow path through preferably one or more of the optional blowers90into preferably a lower portion, more preferably a tangential upper portion of the cyclone203. The cyclone203preferably contains no filters and no catalysts so as to facilitate rotary gas motion for additional liquid separation. Additional optional conduits are preferably provided for passing combustible gas from the cyclone203to flare, to recycle, for testing and for further uses. Additional drain conduit205is also preferably provided for extracting liquids from the cyclone203and returning liquids from the cyclone203to the combustor12for recycling. Operably connected from a lower portion of the cyclone203to the drain conduit205is an optional skim conduit. An optional level sensor, such as a float switch, is preferably disposed in a lower portion of the cyclone203for maintaining liquid levels within the cyclone203at desired levels. It is understood that the cyclone203may take any number of different sizes, shapes and configurations and that any number of different filter media or catalysts or different combinations of filter media and catalysts may be used in the cyclone203.

Referring toFIG. 5, the conduit206is preferably disposed vertically along the center axis of the cyclone203, opening inside a lower portion of the cyclone203, exiting the cyclone203at the top center of the cyclone203and operably coupling the cyclone203with the demister204, providing a flow path through preferably one or more of the optional blowers90into preferably an upper portion, more preferably a lower portion of the demister204. The demister204preferably contains one or more filters (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other filter known to those skilled in the art). The demister204more preferably contains one or more filters and one or more catalysts (including, but not limited to, ferrous or non-ferrous metals, precious metals, ceramics, minerals, liquids, plastics, fibrous or non-fibrous materials, wood chips, organic or inorganic materials, porous or non-porous materials, natural or artificial materials, absorbents or adsorbents, diatomaceous earth, mixtures or combinations of these and other materials, or any other catalyst known to those skilled in the art). Most preferably, the demister204contains catalyst material whose surface has properties of stainless steel as described above. Additional optional conduits are preferably provided for passing the demisted combustible gas to flare, to recycle, for testing and for further uses. The drain conduit208is also preferably provided for extracting liquids from the demister204and returning liquids from the demister204to the combustor12for recycling. An optional skim conduit is also preferably provided at a lower portion of the demister204. An optional level sensor, such as a float switch, is preferably disposed in a lower portion of the demister204for maintaining liquid levels within the demister204at desired levels. It is understood that the demister204may take any number of shapes, sizes and configurations and that any number of different filter media or catalysts or different combinations of filter media and catalysts may be used in the demister204. It is also understood that the sequence of scrubber14, fixer16, cyclone203and demister204may be rearranged to adjust characteristics of the gas and liquids.

In operation, referring toFIG. 1, the fuel conduit24provides solid or semi-solid carbonaceous fuel to the combustor12. Referring toFIG. 2, the solid or semi-solid carbonaceous fuel from the fuel conduit24enters an upper portion of the combustor12, drops through the inner chamber30, is at least partially combusted, accumulates on the ash support member36and builds up within the inner chamber30to a level above the fuel stirring member52. Fuel stirring member52agitates and preferably partially levels the carbonaceous fuel. Fuel stirring member52also reduces and preferably prevents carbonaceous fuel channeling, bridging, clumping, voids, and similar problems. As seen inFIGS. 1 and 5, an oxygen source, such as air, is provided preferably via auxiliary air conduit124and an auxiliary fuel source is provided preferably via auxiliary fuel conduit126. Referring toFIG. 2, the air and auxiliary fuel are mixed inside conduit or gas manifold46, ignited by igniter50and transferred into the combustor12through openings42. The burning mixture of air and auxiliary fuel heats the carbonaceous fuel within the inner chamber30. Once measured temperatures within the lower portion of inner chamber30exceed preferably at least 120 degrees Celsius (248 degrees Fahrenheit) and preferably no more than 260 degrees Celsius (500 degrees Fahrenheit), it is preferable for the overall efficiency of the system10,200that auxiliary fuel sources be at least partially shut off, the igniter50be at least partially shut off and recycled material from other portions of the system10,200entering the combustor12be sufficient to continue normal operation. As the carbonaceous fuel passes downward within the inner chamber30, the carbonaceous fuel sources are at least partially combusted to produce, among other materials, ash and a combustible gas.

Referring toFIG. 2, ash passes through opening34and collects on ash support member36. The combustion bed stirrer54prevents excessive ash accumulation by moving the collecting ash preferably outward so that the ash spills or passes from the outer periphery of the ash support member36, more preferably moving the collecting ash downward so that the ash spills or passes through perforations in ash support member36, most preferably moving the collecting ash both outward over the outer periphery of ash support member36and downward through perforations in ash support member36so that the ash falls down to the lower base portion22of the combustor12. Other than the combustion bed stirrer54and support members38, the area between the opening34of the inner wall28and the top surface of ash support member36is substantially unobstructed to provide a ready path for ash removal. The ash support member36is affixed below the inner wall28, preferably by support members38, more preferably by affixing portions of the outer edge of ash support member36to the upper outer wall portion20or the lower outer wall portion22. The ash support member36is affixed in a manner that allows ash to spill from the ash support member36preferably over at least approximately 70 percent of the outer periphery of the ash support member36, more preferably over at least approximately 80 percent of the outer periphery of the ash support member36, and most preferably over at least approximately 90 percent of the outer periphery of the ash support member36.

Referring toFIG. 2, ash that accumulates in the lower base portion22of the combustor12passes through an opening in the bottom of the combustor12and is removed by the ash removal conduit64. The ash removal conduit64is operably coupled with the optional ash level sensor70to maintain the level of ash in the combustor12below a desired amount. The ash removed from the combustor12is typically a salable product. For example, the ash may be suitable for sale as fertilizer, soil stabilizer, filter material and as an extender for mortar, concrete, or road material, among other uses.

Referring toFIG. 2, the fuel level sensor68is operably coupled with the fuel conduit24to maintain the level of solid or semi-solid fuel within a desired height range within the inner chamber30. The desired height range may vary depending upon a number of factors, including, but not limited to, the properties of the solid or semi-solid fuel. It is typically desirable to maintain the solid or semi-solid fuel level within the inner chamber30at a level that maintains an adequate partial seal, preferably to help regulate the flow of products of combustion from the combustor12through the conduit66, preferably to facilitate heating of the carbonaceous fuel and preferably to help control the degree of partial combustion within the inner chamber30. The preferable level may vary with factors such as the density and moisture content of the solid or semi-solid fuel. For example, the preferable level for a solid or semi-solid fuel comprised primarily of chicken litter (including, but not limited to, chicken waste products, absorbents such as rice hulls or wood chips, or any combination of these and similar or related materials), wood pulp or paper mill sludge, or sanding dust or wood dust is approximately 25 inches (approximately 64 centimeters) above the ash support member36.

Referring toFIG. 1, the optional blowers90draw products of combustion preferably downward, more preferably upward, through the combustor12so that they pass through the opening34in the inner wall28and upwardly through preferably the outer chamber32, more preferably the inner chamber30before passing through conduit66. Material from the combustor12travels through conduit66and enters preferably an upper portion, more preferably a lower portion, of the scrubber14. The optional pump72preferably circulates liquid, for example water with impurities therein, through the scrubber14. The circulated liquid cools and scrubs the combustible gas, removing matter from the combustible gas including, but not limited to, tar, oil and particulates. The liquid level in the scrubber14is preferably maintained at a level so that tar, oil and similar matter may be removed from the scrubber14, preferably via the skim conduit84. Particulates, water and preferably other components that settle to the bottom of the scrubber14are removed via the drain conduit86. The optional valves128are also opened preferably intermittently so that the optional pump72may circulate liquid through the optional wash conduit80and through the conduits66,82and104for cleaning. The optional valve130may also be opened preferably periodically so that the liquid in the scrubber14may be drained through the conduit86into conduit114. Optional filters in the scrubber14preferably help remove liquids and particulates from the gas. Catalysts in the scrubber14primarily improve the chemical composition of the gas and preferably also help remove liquids and particulates from the gas.

Referring toFIG. 1, the scrubbed combustible gas exits the scrubber14through conduit82and passes through one or more of the optional blowers90into fixer16. Wastewater and other matter that are removed from the combustible gas and that are not absorbed by the wood chips or other filters fall to the bottom of the fixer16and are removed via conduit112. Optional filters in the fixer16preferably help remove liquids and particulates from the gas. Catalysts in the fixer16primarily improve the chemical composition of the gas and preferably also help remove liquids and particulates from the gas. Scrubbed, fixed combustible gas exits the fixer16via conduit106. From there the combustible gas is flared via optional conduit108, returned to the combustor12via optional conduit48, or sent to other uses via optional conduit110, for example, as shown inFIG. 5, to cyclone203and demister204.

Referring toFIGS. 1 and 5, during the system10,200start-up phase, the combustible gas is flared until it is determined that gas is being produced at a desired quantity and quality. Once the system10,200start-up phase is complete, the combustible gas may be passed via optional conduit110,207to produce work or for further uses elsewhere. For example, the combustible gas may be combusted to supply heat to a process or may be combusted within a motor or turbine to produce work or to generate electricity. As additional examples, the combustible gas produced by the system10,200may be used in brooder heaters in poultry houses, in internal combustion engines, to heat boilers and to provide heat for the production of petroleum substitutes such as methanol.

Referring toFIGS. 1 and 5, depending upon the properties of the carbonaceous fuels being supplied to the combustor12, such as the moisture content, a portion of the combustible gas is preferably returned to the combustor12via conduit48and a portion of the liquid is preferably returned to the combustor12via conduit26to facilitate the partial combustion of the carbonaceous fuel. The returned combustible gas and recycled liquid preferably serve as a complete or partial replacement for the auxiliary fuel source supplied to the combustor12, particularly after the system10,200start-up phase is complete. Returning a portion of the combustible gas and a portion of the liquid to the combustor12tends to reduce the need for auxiliary fuel to maintain the desired partial combustion in the combustor12and tends to improve the overall efficiency of typical embodiments of the system10,200.

Referring toFIGS. 1 and 5, conduits86,84,112,205,207and208connect the scrubber14, the fixer16, the cyclone203and the demister204to the conduit114, which connects to the pump118. These conduits86,84,112,205,207and208pass wastewater, excess liquid from wet fuel components, tar, oil, particulate matter, condensate, and other removed substances to the conduit114which connects to the pump118. The output of pump118is preferably recycled via conduit26back into the combustor12. Returning the wastewater, liquids and other components to the combustor12provides a number of advantages. For example, the recycled wastewater tends to scavenge additional, residual carbon from the ash as the liquid is broken down. This recycling of liquid provides for improved recovery of the heating value from the carbonaceous fuel and eliminates or drastically reduces the need to dispose of wastewater. A portion of the liquid may also be extracted from the system10,200for use as, for example, a partial replacement for petroleum or petrochemical products in combustion or chemical applications.

The system10,200may be used to process a wide variety of carbonaceous fuels, as well as combinations thereof. The spacing between the ash support member36and the opening34of the inner wall28, as well as the relatively unobstructed side openings there, allow a wide assortment of solid or semi-solid fuels to be used with low risk of clogging. Carbonaceous fuels used successfully in one specific embodiment of system10,200include, but are not limited to, materials such as chicken litter, other animal waste, some municipal solid or semi-solid waste, sanding dust from glued woods (such as plywood or pressboard), paper mill or wood pulp sludge (including, but not limited to, sludge with a moisture content of 65% or higher), wood or yard waste, agricultural waste, biomass, shredded tires and mixtures or combinations of these and other carbonaceous materials. Liquid carbonaceous fuels may also be added to the solid or semi-solid carbonaceous fuel, including, but not limited to, waste petroleum products, used motor oil, used cooking oil and carbonaceous liquids extracted from the system10,200itself. Adding such liquid carbonaceous fuels can markedly increase the overall efficiency of typical embodiments of the system10,200.

One specific embodiment of the system10,200is approximately 6 feet (1.8 meters) wide, approximately 12 feet (3.7 meters) long and approximately 8 feet (2.4 meters) tall. This specific embodiment of system10,200gasifies approximately eighty (80) pounds (36 kilograms) of chicken litter per hour, requires no auxiliary fuel after start-up, uses approximately ten (10) kilowatt-hours of electricity, and produces approximately ten (10) pounds (4.5 kilograms) per hour of mineral ash, generating no other solid waste, no liquid waste, and essentially no gaseous waste.

The emissions test results in Example 1 below illustrate that at least one specific embodiment of the system10,200can produce combustible gas that is environmentally relatively benign, while processing solid or semi-solid carbonaceous fuels that previously posed serious landfill issues.

An emissions test was conducted on combustible gas generated by one specific embodiment of the system10,200while combusting chicken litter. A sample run of approximately 60 minutes in duration was performed. Testing was performed in approximate accordance with the methods detailed in 40 Code of Federal Regulations (CFR), Part 60, Appendix A. The flow, based on the lowest recordable flow, had a velocity of approximately 6 feet per second (1.8 meters per second) and the sample collected had a volume of approximately 40 dry standard cubic feet (1000 liters). The results of the emissions testing for Example 1 are summarized in Table 1 below.

An emissions test was conducted on combustible gas generated by one specific embodiment of the system10,200while combusting paper mill sludge. A sample run of approximately 60 minutes in duration was performed. Testing was performed in approximate accordance with the methods detailed in 40 CFR, Part 60, Appendix A. The flow, based on the lowest recordable flow, had a velocity of approximately 6 feet per second (1.8 meters per second) and the sample collected had a volume of approximately 40 dry standard cubic feet (1000 liters). The results of the emissions testing for Example 2 are summarized in Table 2 below.

Other modifications, changes and substitutions are intended in the foregoing and, in some instances, some features of the invention may be employed without a corresponding use of other features. For example, the configuration of the ash support member36may be used in combination with any number of different gasification systems, regardless of whether such systems also use other features of the present invention, and may also find uses in systems other than gasification systems. Similarly, the gaseous return and liquid recycling features of the present invention may be used separately or in combination with any number of different gasification systems, regardless of whether such systems also use other features of the present invention, and may also find uses in systems other than gasification systems. Further, the wood chip filtering or other filters or catalysts of the present invention may be used in combination with any number of different gasification systems, regardless of whether such systems also use other features of the present invention, and may also find uses in systems other than gasification systems. Further still, the design of the blower90of the present invention may be used in combination with any number of different gasification systems, regardless of whether such systems also use other features of the present invention, and may also find uses in systems other than gasification systems. Of course, quantitative information is included by way of example only and is not intended as a limitation as to the scope of the invention. Accordingly, it is appropriate that the invention be construed broadly and in a manner consistent with the scope of the invention disclosed.

Although the present invention has been described in considerable detail with reference to certain preferred versions or embodiments thereof, other versions or embodiments are possible. For example, versions or embodiments having different component dimensions, different numbers and placements of blowers, different numbers and placements of vessels, different numbers and placements of stirring members, different combinations of components, different sequences of components, or subsets of these and other differences are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the preferred versions or embodiments contained herein.