CA2937445C - Wood gasification - Google Patents
Wood gasification Download PDFInfo
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- CA2937445C CA2937445C CA2937445A CA2937445A CA2937445C CA 2937445 C CA2937445 C CA 2937445C CA 2937445 A CA2937445 A CA 2937445A CA 2937445 A CA2937445 A CA 2937445A CA 2937445 C CA2937445 C CA 2937445C
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/72—Other features
- C10J3/82—Gas withdrawal means
- C10J3/84—Gas withdrawal means with means for removing dust or tar from the gas
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J3/00—Production of combustible gases containing carbon monoxide from solid carbonaceous fuels
- C10J3/02—Fixed-bed gasification of lump fuel
- C10J3/20—Apparatus; Plants
- C10J3/22—Arrangements or dispositions of valves or flues
- C10J3/24—Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed
- C10J3/26—Arrangements or dispositions of valves or flues to permit flow of gases or vapours other than upwardly through the fuel bed downwardly
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/24—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies
- B01D46/2403—Particle separators, e.g. dust precipitators, using rigid hollow filter bodies characterised by the physical shape or structure of the filtering element
- B01D46/2407—Filter candles
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10K—PURIFYING OR MODIFYING THE CHEMICAL COMPOSITION OF COMBUSTIBLE GASES CONTAINING CARBON MONOXIDE
- C10K1/00—Purifying combustible gases containing carbon monoxide
- C10K1/02—Dust removal
- C10K1/024—Dust removal by filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2273/00—Operation of filters specially adapted for separating dispersed particles from gases or vapours
- B01D2273/20—High temperature filtration
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10J—PRODUCTION OF PRODUCER GAS, WATER-GAS, SYNTHESIS GAS FROM SOLID CARBONACEOUS MATERIAL, OR MIXTURES CONTAINING THESE GASES; CARBURETTING AIR OR OTHER GASES
- C10J2300/00—Details of gasification processes
- C10J2300/09—Details of the feed, e.g. feeding of spent catalyst, inert gas or halogens
- C10J2300/0913—Carbonaceous raw material
- C10J2300/0916—Biomass
- C10J2300/092—Wood, cellulose
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E20/00—Combustion technologies with mitigation potential
- Y02E20/16—Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT]
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Geometry (AREA)
- Processing Of Solid Wastes (AREA)
- Solid-Fuel Combustion (AREA)
Abstract
The invention relates to an apparatus and a method for gasifying wood, having a gas generator (1), to which the material for gasification and oxygen, usually in the form of air, are supplied, the gasification taking place in a fixed bed reactor. The product gas is drawn off via a product gas line (6) and introduced into a hot gas filter (2), where a filter, preferably provided with filter candles (7), removes solids such as particles not yet gasified, ash and foreign bodies, while the clean gas passes through and is taken off via a clean gas line (8). An outlet (10) is provided in the bottom region of the hot gas filter (2) to take off the residual solids. In order to increase the yield, the invention provides for the hot gas filter (2) to be supplied, in its middle height region, between the filter bottom (13) and the outlet (10), through a line (12), with oxygen, preferably in the form of air.
Description
Wood gasification The invention relates to an apparatus and a method for gasifying wood or other carbon-containing material.
This publication discloses a fluidized bed furnace for a combined-cycle power plant, and provides for the reactor to have a secondary air supply and a tertiary air supply, which enter the reactor at different heights.
US 2008/0127824 Al discloses a regenerative filter for a coal gasification plant, in which uncombusted material is combusted by supply of oxygen, taking place by means of nitrogen/air mixing.
US 6,077,490 provides for similar by means of two filter candles.
Regarding the prior art in general the following may be stated: wood is composed chemically of three principal components:
¨ cellulose ¨ hemicellulose ¨ lignin ¨ remainder Cellulose The principal constituent of all woody plants, at about 50%, is cellulose.
Cellulose is a molecule with a chain construction formed of individual glucose units. The actual building block of the cellulose is cellobiose, a disaccharide.
Hemicellulose Hemicellulose consists of polymeric carbohydrates whose constituents are composed of pentoses and hexoses. Like cellulose, hemicellulose is a polysaccharide.
Date Recue/Date Received 2021-09-17
This publication discloses a fluidized bed furnace for a combined-cycle power plant, and provides for the reactor to have a secondary air supply and a tertiary air supply, which enter the reactor at different heights.
US 2008/0127824 Al discloses a regenerative filter for a coal gasification plant, in which uncombusted material is combusted by supply of oxygen, taking place by means of nitrogen/air mixing.
US 6,077,490 provides for similar by means of two filter candles.
Regarding the prior art in general the following may be stated: wood is composed chemically of three principal components:
¨ cellulose ¨ hemicellulose ¨ lignin ¨ remainder Cellulose The principal constituent of all woody plants, at about 50%, is cellulose.
Cellulose is a molecule with a chain construction formed of individual glucose units. The actual building block of the cellulose is cellobiose, a disaccharide.
Hemicellulose Hemicellulose consists of polymeric carbohydrates whose constituents are composed of pentoses and hexoses. Like cellulose, hemicellulose is a polysaccharide.
Date Recue/Date Received 2021-09-17
- 2 Lignin The third component of wood, at about 25-30% by mass, is lignin, a polymer composed of phenylpropane units.
Remainder In addition to cellulose, hemicellulose, and lignin, the wood also contains fats, resins, terpenes, dyes, and tannins, and also mineral constituents.
Elemental composition Empirical formula of wood:
C61 H904 2 (1.2) Table sugar for comparison:
C12H22011 (2.2) Wood type C [m-%] H [m-%] 0 [m-%] N [m-%] Cl [m-%] Ash [ m-%]
Beech 49 6 44 0.1 0.001 0.9 Spruce 50 6 43 0.05 0.001 0.95 Thermochemical conversion Thermochemical enhancement methods (gasification) transform solid bioenergy carriers, primarily under the influence of heat, into gaseous secondary energy carriers.
In the course of the gasification, biomass is converted at high temperatures very largely completely into burnable gases (i.e., into what is called synthesis gas). The operation is supplied substoichiometrically with an oxygen-containing gasifying agent (air), one of whose abilities is to convert the carbon present in the biomass into carbon monoxide. At the same time, the partial combustion of the feed material provides the required process heat, to allow the gasification process actually to take place (autothermal gasification).
The resulting gas, which is of low calorific value, can be used in burners to provide heat and, among other applications, in gas engines or gas turbines for generating electricity.
Co-current fixed bed gasification With this mode of gasification, the particulate solids (wood) are not agitated by the gas stream. The fuel moves in the form of a bed through the gasifier. The gasification
Remainder In addition to cellulose, hemicellulose, and lignin, the wood also contains fats, resins, terpenes, dyes, and tannins, and also mineral constituents.
Elemental composition Empirical formula of wood:
C61 H904 2 (1.2) Table sugar for comparison:
C12H22011 (2.2) Wood type C [m-%] H [m-%] 0 [m-%] N [m-%] Cl [m-%] Ash [ m-%]
Beech 49 6 44 0.1 0.001 0.9 Spruce 50 6 43 0.05 0.001 0.95 Thermochemical conversion Thermochemical enhancement methods (gasification) transform solid bioenergy carriers, primarily under the influence of heat, into gaseous secondary energy carriers.
In the course of the gasification, biomass is converted at high temperatures very largely completely into burnable gases (i.e., into what is called synthesis gas). The operation is supplied substoichiometrically with an oxygen-containing gasifying agent (air), one of whose abilities is to convert the carbon present in the biomass into carbon monoxide. At the same time, the partial combustion of the feed material provides the required process heat, to allow the gasification process actually to take place (autothermal gasification).
The resulting gas, which is of low calorific value, can be used in burners to provide heat and, among other applications, in gas engines or gas turbines for generating electricity.
Co-current fixed bed gasification With this mode of gasification, the particulate solids (wood) are not agitated by the gas stream. The fuel moves in the form of a bed through the gasifier. The gasification
- 3 -residue is collected in the bottom region of the gasifier. Fuel and gas travel the same route.
Heating and drying The first phase is characterized in that the wood is slowly heated from the outside inward.
Unbound water is given off in the form of steam. This process is endothermic (energy is required).
Degassing and thermal decomposition (pyrolysis) The temperature in the pyrolysis phase or pyrolysis zone ranges between 200 C
and 400 C.
At these temperatures, oxygen (02) and hydrogen (H2) are degassed.
In this phase, the wood building blocks identified in the section above are degassed. In the course of the pyrolysis, from cellulose and hemicellulose, carbon dioxide (CO2) and carbon monoxide (CO) are formed, as are acetic acid (CH3COOH), acetone (C3H60), phenols (C6H5OH), and water (H20). The long-chain hydrocarbons formed during the pyrolysis are referred to as tars.
The thermal decomposition of lignin produces methanol (CH3OH) and aromatic hydrocarbons (e.g., benzene (C6H6)).
The solid product of the pyrolysis is charcoal.
Oxidation The energy needed for the drying, pyrolysis, and reduction is formed in this zone. Carbon and hydrogen give off energy as they combust (exothermic). In this zone, the temperatures range between 650 C and 1100 C, and CO2, H20 and CH4 are formed (without subscription hereinafter), as shown in Figure 1.
Reduction In the reduction zone, the formation of burnable gas is made possible. This is where the actual gasification of the solid carbon occurs. In the reduction zone, the intermediates formed in the Date Recue/Date Received 2021-09-17
Heating and drying The first phase is characterized in that the wood is slowly heated from the outside inward.
Unbound water is given off in the form of steam. This process is endothermic (energy is required).
Degassing and thermal decomposition (pyrolysis) The temperature in the pyrolysis phase or pyrolysis zone ranges between 200 C
and 400 C.
At these temperatures, oxygen (02) and hydrogen (H2) are degassed.
In this phase, the wood building blocks identified in the section above are degassed. In the course of the pyrolysis, from cellulose and hemicellulose, carbon dioxide (CO2) and carbon monoxide (CO) are formed, as are acetic acid (CH3COOH), acetone (C3H60), phenols (C6H5OH), and water (H20). The long-chain hydrocarbons formed during the pyrolysis are referred to as tars.
The thermal decomposition of lignin produces methanol (CH3OH) and aromatic hydrocarbons (e.g., benzene (C6H6)).
The solid product of the pyrolysis is charcoal.
Oxidation The energy needed for the drying, pyrolysis, and reduction is formed in this zone. Carbon and hydrogen give off energy as they combust (exothermic). In this zone, the temperatures range between 650 C and 1100 C, and CO2, H20 and CH4 are formed (without subscription hereinafter), as shown in Figure 1.
Reduction In the reduction zone, the formation of burnable gas is made possible. This is where the actual gasification of the solid carbon occurs. In the reduction zone, the intermediates formed in the Date Recue/Date Received 2021-09-17
- 4 -preceding oxidation, such as CO2 and H20, are reduced over the glowing charcoal. The products here are CO, H2, and higher hydrocarbons. This occurs at about 1100-650 C.
The process of reduction is dependent on the prevailing temperature. The reaction of hydrogen and carbon to form methane decreases sharply between 400 C and 600 C.
At temperatures above 1000 C, methane is no longer formed. At high temperatures, the Boudouard reaction attains a good yield of carbon monoxide. This reaction is relatively slow.
There is a divergent tendency, dependent on temperature, between high CO
production and high hydrogen production. Furthermore, hydrogen production falls back in favor of methane formation. Both components act to increase the heating value. High hydrogen content also increases the problem of engine knocking. Knock-resistant methane is a good fuel gas, but experience suggests that gas generation conducted to a high methane content also entails a high tar loading in the gas.
Date Recue/Date Received 2021-09-17
The process of reduction is dependent on the prevailing temperature. The reaction of hydrogen and carbon to form methane decreases sharply between 400 C and 600 C.
At temperatures above 1000 C, methane is no longer formed. At high temperatures, the Boudouard reaction attains a good yield of carbon monoxide. This reaction is relatively slow.
There is a divergent tendency, dependent on temperature, between high CO
production and high hydrogen production. Furthermore, hydrogen production falls back in favor of methane formation. Both components act to increase the heating value. High hydrogen content also increases the problem of engine knocking. Knock-resistant methane is a good fuel gas, but experience suggests that gas generation conducted to a high methane content also entails a high tar loading in the gas.
Date Recue/Date Received 2021-09-17
- 5 Course of the gasification process First, wood is heated by supply of heat, and at the same time the water present in the gasifier material is evaporated. The quantity of heat required is generated by the partial combustion of the resultant carbonization gases and the oxidation of carbon and hydrogen.
The resultant charcoal serves as a reaction area for the oxidation and reduction of carbon, carbon monoxide, carbon dioxide, and hydrogen. In the course of this process, the charcoal reduces in size, meaning that the surface area of the particles becomes greater, and hence the reaction rate goes up.
It is clear here that the reaction zone must be regarded as a whole and that the reduction and oxidation proceed simultaneously.
Since the reduction of the carbon dioxide by the charcoal is endothermic, the temperature falls from bottom to top, causing the reactions to subside. There is no clear separation between reduction zone and oxidation zone.
It is thought that in the oxidation zone the carbon undergoes combustion to form CO2, since CO2 is no longer stable at the high temperatures prevailing there, of 1000-1300 C.
A portion of the carbon monoxide is supposed then to be combusted to form CO2 in the presence of oxygen. This CO2, however, is unstable on account of the high temperatures, and is reduced to CO over the glowing carbon. When the oxygen has all been used up, CO no longer undergoes combustion, and remains stable in its concentration in spite of the decreasing temperature. Therefore, according to the last consideration, however, reduction reactions must also be assumed here, since to start with CO2 is present.
As becomes clear from the procedures referred to above, the gasification produces a mixture of burnable and nonburnable gases, which divide up as follows:
1. burnable gases:
= carbon monoxide CO
= hydrogen H2 = methane CH4 e higher molecular mass hydrocarbon compounds
The resultant charcoal serves as a reaction area for the oxidation and reduction of carbon, carbon monoxide, carbon dioxide, and hydrogen. In the course of this process, the charcoal reduces in size, meaning that the surface area of the particles becomes greater, and hence the reaction rate goes up.
It is clear here that the reaction zone must be regarded as a whole and that the reduction and oxidation proceed simultaneously.
Since the reduction of the carbon dioxide by the charcoal is endothermic, the temperature falls from bottom to top, causing the reactions to subside. There is no clear separation between reduction zone and oxidation zone.
It is thought that in the oxidation zone the carbon undergoes combustion to form CO2, since CO2 is no longer stable at the high temperatures prevailing there, of 1000-1300 C.
A portion of the carbon monoxide is supposed then to be combusted to form CO2 in the presence of oxygen. This CO2, however, is unstable on account of the high temperatures, and is reduced to CO over the glowing carbon. When the oxygen has all been used up, CO no longer undergoes combustion, and remains stable in its concentration in spite of the decreasing temperature. Therefore, according to the last consideration, however, reduction reactions must also be assumed here, since to start with CO2 is present.
As becomes clear from the procedures referred to above, the gasification produces a mixture of burnable and nonburnable gases, which divide up as follows:
1. burnable gases:
= carbon monoxide CO
= hydrogen H2 = methane CH4 e higher molecular mass hydrocarbon compounds
-6-2. nonburnable gases:
= carbon dioxide CO2 = nitrogen N2 = steam H2O
= small amounts of oxygen 02 Volume Heating Minimum Methane Components fraction value air mass number Ivol%1 IMJ/m31 11113aidifi3gas]
Hydrogen H2 17.1-19.8 10.8 2.36 0 Oxygen 02 0.4-0.6 0 Nitrogen N2 45 0 Carbon monoxide 20-23.8 12.6 2.41 75-100 CO
Carbon dioxide 8.5-16.2 0 Methane CH4 1.5-2.9 35.9 9.57 100 Higher HCs Cmlin 0.2 variable Process regime, residence time, temperature and fuel type, particle sizing and moisture influence the composition of the wood gas. Typical heating values for wood are in the order of magnitude of 3.5-5.5 MJ/m3, making wood gas a weak gas.
Given that 5-10 wt% of the starting material remains as ash, but primarily as ungasified wood residues, and must be properly disposed of, there is both economic and environmental interest in likewise maximizing the gasification of these wood constituents that are obtained in uncombusted form in wood gasifications in accordance with the prior art. This is also the object of the invention.
Date Recue/Date Received 2021-09-17
= carbon dioxide CO2 = nitrogen N2 = steam H2O
= small amounts of oxygen 02 Volume Heating Minimum Methane Components fraction value air mass number Ivol%1 IMJ/m31 11113aidifi3gas]
Hydrogen H2 17.1-19.8 10.8 2.36 0 Oxygen 02 0.4-0.6 0 Nitrogen N2 45 0 Carbon monoxide 20-23.8 12.6 2.41 75-100 CO
Carbon dioxide 8.5-16.2 0 Methane CH4 1.5-2.9 35.9 9.57 100 Higher HCs Cmlin 0.2 variable Process regime, residence time, temperature and fuel type, particle sizing and moisture influence the composition of the wood gas. Typical heating values for wood are in the order of magnitude of 3.5-5.5 MJ/m3, making wood gas a weak gas.
Given that 5-10 wt% of the starting material remains as ash, but primarily as ungasified wood residues, and must be properly disposed of, there is both economic and environmental interest in likewise maximizing the gasification of these wood constituents that are obtained in uncombusted form in wood gasifications in accordance with the prior art. This is also the object of the invention.
Date Recue/Date Received 2021-09-17
- 7 -According to an aspect of the present invention, there is provided an apparatus for gasifying carbon-containing material, comprising: a gas generator; the gas generator having an upper region, a middle region, and a lower region; wherein the carbon-containing material is supplied to the upper region of the gas generator, oxygen is supplied to the middle region of the gas generator, and the carbon-containing material is largely gasified to a product gas in a fixed bed reactor in the lower region of the gas generator; a hot gas filter, wherein the hot gas filter receives the product gas from the gas generator via a product gas line coupled to the lower region of the gas generator and passes the product gas through a filter assembly to yield a clean gas; the hot gas filter further including a solids outlet in a bottom region of the hot gas filter for taking off residual solids removed from the product gas by the filter assembly; and a gas line configured to supply oxygen to a middle region of the hot gas filter between the filter assembly and the solids outlet, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
According to another aspect of the present invention, there is provided a method of gasifying carbon-containing material, comprising: gasifying, in a gas generator, the carbon-containing material to a product gas; passing the product gas to a hot gas filter having a filter assembly and a solids outlet for taking off residual solids removed from the product gas by the filter assembly; passing the product gas through the filter assembly to yield a clean gas; supplying, between the filter assembly and the solids outlet, oxygen to the product gas, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
.. Brief Description of the Drawings Figure 1 is a chart depicting selected processes occurring during gasification of carbon-containing materials, and their products;
Figure 2 is a schematic depiction of a gasification plant according to an example embodiment of the invention.
Date Recue/Date Received 2021-09-17 - 7a -Detailed Description of Example Embodiments In an embodiment of the present invention, the charcoal obtained in ungasified form in the bottom region of the gas generator is at least predominantly transferred with the gas stream to the downstream hot gas filter. This can be carried out through appropriate choice of the flow rate in the manner of pneumatic transport, as has long been known in the conveying of bulk goods. In the hot gas filter, charcoal, along with coal dust and entrained ash, is deposited on the surface of the filter, composed preferably of filter candles. Depending on the pressure drop at the filter upstream of the filter candles, oxygen (usually in the form of air) is introduced in as far as possible a pulselike manner, causing the filter cake on the filter candles to break apart, and, promoted by pressure wave and temperature, there is a second gasification step, through which the entrained charcoal and/or the coal dust is to by far the predominant extent gasified. The fraction that is still not being gasified is ultimately gasified by the oxygen supplied in the bottom part of the filter ¨ again preferably in the form of air. Depending on the process parameters, which are easily determined for the plant constructor and the plant operator, if not being already known anyway, it is possible to carry out the gasification of wood substantially completely, leaving only the mineral ash.
A plant according to an embodiment of the invention is depicted purely schematically in Figure 2. The depiction of all of the components which are not causally associated with the invention has been left out. In particular, the numerous meters, the regulating and shutoff elements, the control, the components upstream and downstream of the plant, such as stores, drying apparatus, final product gas cleaning, and transfer to the user, are very well known to the person skilled in the field of wood gasification plants, and require no more detailed elucidation in connection with the invention.
The plant of an embodiment of the invention, with its components and elements necessary for the invention ¨ albeit without the meters, etc. ¨ is depicted schematically in Figure 2, and features essentially the following: a gas generator 1 and a hot gas filter 2.
Wood chips, wood pellets, coal or the like, from a reservoir bunker which is not shown, are supplied via a feed 3 to the gas generator 1, appropriately at its top, and, in the generator, they pass through the Date Recue/Date Received 2021-09-17 - 7b -steps, known from the prior art and referred to at the outset, of drying, of carbonization, of oxidation, and of reduction; in the bottom region, indicated by the installation 4, air is appropriately supplied by a line and a distributor Date Recue/Date Received 2021-09-17
According to another aspect of the present invention, there is provided a method of gasifying carbon-containing material, comprising: gasifying, in a gas generator, the carbon-containing material to a product gas; passing the product gas to a hot gas filter having a filter assembly and a solids outlet for taking off residual solids removed from the product gas by the filter assembly; passing the product gas through the filter assembly to yield a clean gas; supplying, between the filter assembly and the solids outlet, oxygen to the product gas, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
.. Brief Description of the Drawings Figure 1 is a chart depicting selected processes occurring during gasification of carbon-containing materials, and their products;
Figure 2 is a schematic depiction of a gasification plant according to an example embodiment of the invention.
Date Recue/Date Received 2021-09-17 - 7a -Detailed Description of Example Embodiments In an embodiment of the present invention, the charcoal obtained in ungasified form in the bottom region of the gas generator is at least predominantly transferred with the gas stream to the downstream hot gas filter. This can be carried out through appropriate choice of the flow rate in the manner of pneumatic transport, as has long been known in the conveying of bulk goods. In the hot gas filter, charcoal, along with coal dust and entrained ash, is deposited on the surface of the filter, composed preferably of filter candles. Depending on the pressure drop at the filter upstream of the filter candles, oxygen (usually in the form of air) is introduced in as far as possible a pulselike manner, causing the filter cake on the filter candles to break apart, and, promoted by pressure wave and temperature, there is a second gasification step, through which the entrained charcoal and/or the coal dust is to by far the predominant extent gasified. The fraction that is still not being gasified is ultimately gasified by the oxygen supplied in the bottom part of the filter ¨ again preferably in the form of air. Depending on the process parameters, which are easily determined for the plant constructor and the plant operator, if not being already known anyway, it is possible to carry out the gasification of wood substantially completely, leaving only the mineral ash.
A plant according to an embodiment of the invention is depicted purely schematically in Figure 2. The depiction of all of the components which are not causally associated with the invention has been left out. In particular, the numerous meters, the regulating and shutoff elements, the control, the components upstream and downstream of the plant, such as stores, drying apparatus, final product gas cleaning, and transfer to the user, are very well known to the person skilled in the field of wood gasification plants, and require no more detailed elucidation in connection with the invention.
The plant of an embodiment of the invention, with its components and elements necessary for the invention ¨ albeit without the meters, etc. ¨ is depicted schematically in Figure 2, and features essentially the following: a gas generator 1 and a hot gas filter 2.
Wood chips, wood pellets, coal or the like, from a reservoir bunker which is not shown, are supplied via a feed 3 to the gas generator 1, appropriately at its top, and, in the generator, they pass through the Date Recue/Date Received 2021-09-17 - 7b -steps, known from the prior art and referred to at the outset, of drying, of carbonization, of oxidation, and of reduction; in the bottom region, indicated by the installation 4, air is appropriately supplied by a line and a distributor Date Recue/Date Received 2021-09-17
- 8 system 5. This apparatus is a conventional wood gasifier having a fixed bed operated in co-current. In the bottom region, after the oxidation, there is reduction, and uncombusted portions and ash are drawn off with the product gas via a line 6 in the bottom region of the gas generator, and are introduced into the middle region of a hot .. gas filter 2.
Projecting into the bottom region of the hot gas filter 2 are filter candles 7 comprising a filter bottom 13, directed downward. Although one filter candle is sufficient under certain circumstances, it is favorable, for continuous operation, though not vital, for at least two such filter candles 7 to be provided. The product gas passes through the filter candles and arrives, here as product referred to as clean gas, into the upper region of the hot gas filter 2, from where it is taken off via a clean gas line 8 and supplied for further processing and/or use.
The filter candles 7 are connected controllably to a pressurized air supply 9;
by means of this compressed air supply, they can be placed in a pulselike manner, on their clean gas side, under superatmospheric pressure, in order to burst filter cakes which have collected on the crude gas side and to permit at least partial gasification.
Provided in the bottom region of the hot gas filter 2 is an outlet 10 for the ungasified constituents and a corresponding ash vat 11.
Then, in accordance with the invention, as already mentioned, via line 12, oxygen, in the form for example of air, optionally heated and/or dried, is supplied into the region below the filter bottom 13 (approximately at the lower end of the filter candles), and consequently, in the crude gas region of the hot gas filter 2, there is a further, very largely complete gasification of those constituents of the wood that up to this point have not been gasified.
In this way, the remaining, ungasified fraction of the wood can be reduced substantially to the mineral ash, with notable consequences both for the environment and in economic respects: in the prior art, 5 to 10 wt% of the fuel used is ungasifiable, and therefore requires proper disposal; as a result of the invention, this fraction is compressed to less than 1 wt% of the fuel used, and so the invention produces a boost in
Projecting into the bottom region of the hot gas filter 2 are filter candles 7 comprising a filter bottom 13, directed downward. Although one filter candle is sufficient under certain circumstances, it is favorable, for continuous operation, though not vital, for at least two such filter candles 7 to be provided. The product gas passes through the filter candles and arrives, here as product referred to as clean gas, into the upper region of the hot gas filter 2, from where it is taken off via a clean gas line 8 and supplied for further processing and/or use.
The filter candles 7 are connected controllably to a pressurized air supply 9;
by means of this compressed air supply, they can be placed in a pulselike manner, on their clean gas side, under superatmospheric pressure, in order to burst filter cakes which have collected on the crude gas side and to permit at least partial gasification.
Provided in the bottom region of the hot gas filter 2 is an outlet 10 for the ungasified constituents and a corresponding ash vat 11.
Then, in accordance with the invention, as already mentioned, via line 12, oxygen, in the form for example of air, optionally heated and/or dried, is supplied into the region below the filter bottom 13 (approximately at the lower end of the filter candles), and consequently, in the crude gas region of the hot gas filter 2, there is a further, very largely complete gasification of those constituents of the wood that up to this point have not been gasified.
In this way, the remaining, ungasified fraction of the wood can be reduced substantially to the mineral ash, with notable consequences both for the environment and in economic respects: in the prior art, 5 to 10 wt% of the fuel used is ungasifiable, and therefore requires proper disposal; as a result of the invention, this fraction is compressed to less than 1 wt% of the fuel used, and so the invention produces a boost in
- 9 yield from 90%-95% to 99%, with the plus of a reduction in waste to 10-20% of the previous level of waste. On the other side are the negligible extra costs of strengthening the draft in line 6, and the costs for the blowing of the reaction air through line 12 into the hot gas filter 2, which are insubstantial.
The invention is not confined to the exemplary embodiment shown, but can be modified in a variety of ways. For instance, with large plants, a plurality of gas generators and/or of hot gas filters can be fittingly combined with one another, in order to obtain continuous operation even in the event of maintenance. For wood constituents which are too heavy even for the increased draft, a discharge device for such parts can be provided in the gas generator; whether these parts are subsequently resupplied to the gas generator or else disposed of depends on the nature of the starting material and the possibility for return into the product stream.
The invention can be combined with various other embodiments of the method or of the apparatus, as long as the only reaction in the hot gas filter is not disrupted and/or the other embodiments of the filter operation do not cause disruption.
As a result of the implementation of the second gasification step in the hot gas filter, the status conditions there are not changed in so substantial a manner as to necessitate a change in or adaptation of the materials, and it is therefore possible to use all the components and materials which are also contemplated for this purpose by the skilled person with conventional hot gas filters.
The level of the entry of nozzles or other openings of the supply line 12 into the hot gas filter 2 is appropriately, when filter candles 7 are present, at the bottom end thereof.
There, when the filter cake is burst apart, the entire material will pass in front, just as, during undisrupted operation, the material not yet gasified likewise passes in front.
Operating parameters such as superatmospheric pressure and volume flow rate are easily determined by means of a few trials. If different materials are being degassed, it is advantageous under certain circumstances to provide nozzles at different heights, which may be provided individually or in groups.
The invention is not confined to the exemplary embodiment shown, but can be modified in a variety of ways. For instance, with large plants, a plurality of gas generators and/or of hot gas filters can be fittingly combined with one another, in order to obtain continuous operation even in the event of maintenance. For wood constituents which are too heavy even for the increased draft, a discharge device for such parts can be provided in the gas generator; whether these parts are subsequently resupplied to the gas generator or else disposed of depends on the nature of the starting material and the possibility for return into the product stream.
The invention can be combined with various other embodiments of the method or of the apparatus, as long as the only reaction in the hot gas filter is not disrupted and/or the other embodiments of the filter operation do not cause disruption.
As a result of the implementation of the second gasification step in the hot gas filter, the status conditions there are not changed in so substantial a manner as to necessitate a change in or adaptation of the materials, and it is therefore possible to use all the components and materials which are also contemplated for this purpose by the skilled person with conventional hot gas filters.
The level of the entry of nozzles or other openings of the supply line 12 into the hot gas filter 2 is appropriately, when filter candles 7 are present, at the bottom end thereof.
There, when the filter cake is burst apart, the entire material will pass in front, just as, during undisrupted operation, the material not yet gasified likewise passes in front.
Operating parameters such as superatmospheric pressure and volume flow rate are easily determined by means of a few trials. If different materials are being degassed, it is advantageous under certain circumstances to provide nozzles at different heights, which may be provided individually or in groups.
- 10 -It is also possible, through slanted arrangement of nozzles, to obtain specific flow patterns through which the further gasification is promoted.
In summary it may be stated that the invention provides an apparatus for gasifying carbon-containing material, more particularly wood, having a gas generator 1, to which the material for gasification is supplied in its upper region and to which oxygen, usually in the form of air, is supplied in its middle region, and in whose lower region it is largely gasified in a fixed bed reactor, the product gas being drawn off via a product gas line 6 from the lowermost region of the gas generator 1 and introduced into the lower region of a hot gas filter 2, where a filter, preferably provided with filter candles 7, removes solids such as particles not yet gasified, ash, and foreign bodies, while the clean gas passes through and is taken off via a clean gas line 8, an outlet 10 being provided for taking off the residual solids in the bottom region of the hot gas filter 2.
Here, the hot gas filter 2 is supplied in its middle height region, between the filter bottom 13 and the outlet 10, through a line 12, with oxygen, preferably in the form of air.
The invention also relates to a method for gasifying carbon-containing material, more particularly wood, featuring a gas generator 1 and a hot gas filter 2 downstream thereof in the product stream, wherein the hot gas filter 2 is supplied, ahead of the filter in the product stream, with oxygen, preferably in the form of air, and so a further gasification procedure takes place.
It should also be noted that details such as "largely" in the case of materials mean more than 50 wt%, preferably more than 80 wt%, and more preferably more than 95 wt%;
that "bottom region" of a reactor, filter, construction, or apparatus or, very generally, of an article, means the lower half and more particularly the lower quarter of the overall height, "lowermost region" means the lowermost quarter and more particularly an even smaller part; while "middle region" refers to the middle third of the overall height. All of these details, along with 'top", "bottom", etc., have their generally accepted meaning, applied to the as-defined position of the article under consideration.
In summary it may be stated that the invention provides an apparatus for gasifying carbon-containing material, more particularly wood, having a gas generator 1, to which the material for gasification is supplied in its upper region and to which oxygen, usually in the form of air, is supplied in its middle region, and in whose lower region it is largely gasified in a fixed bed reactor, the product gas being drawn off via a product gas line 6 from the lowermost region of the gas generator 1 and introduced into the lower region of a hot gas filter 2, where a filter, preferably provided with filter candles 7, removes solids such as particles not yet gasified, ash, and foreign bodies, while the clean gas passes through and is taken off via a clean gas line 8, an outlet 10 being provided for taking off the residual solids in the bottom region of the hot gas filter 2.
Here, the hot gas filter 2 is supplied in its middle height region, between the filter bottom 13 and the outlet 10, through a line 12, with oxygen, preferably in the form of air.
The invention also relates to a method for gasifying carbon-containing material, more particularly wood, featuring a gas generator 1 and a hot gas filter 2 downstream thereof in the product stream, wherein the hot gas filter 2 is supplied, ahead of the filter in the product stream, with oxygen, preferably in the form of air, and so a further gasification procedure takes place.
It should also be noted that details such as "largely" in the case of materials mean more than 50 wt%, preferably more than 80 wt%, and more preferably more than 95 wt%;
that "bottom region" of a reactor, filter, construction, or apparatus or, very generally, of an article, means the lower half and more particularly the lower quarter of the overall height, "lowermost region" means the lowermost quarter and more particularly an even smaller part; while "middle region" refers to the middle third of the overall height. All of these details, along with 'top", "bottom", etc., have their generally accepted meaning, applied to the as-defined position of the article under consideration.
- 11 -"Substantially" can be delimited with a deviation of 10% from the stated figure, if physically possible, both upwardly and downwardly, or otherwise only in the direction that makes sense.
List of reference symbols:
01 Gasifier 08 Clean gas line 02 Hot air filter 09 Compressed air supply 03 Supply 10 Outlet 04 Installation 11 Ash bin 05 Distributor system 12 Supply line 06 Product line 13 Filter bottom 07 Filter candle(s)
List of reference symbols:
01 Gasifier 08 Clean gas line 02 Hot air filter 09 Compressed air supply 03 Supply 10 Outlet 04 Installation 11 Ash bin 05 Distributor system 12 Supply line 06 Product line 13 Filter bottom 07 Filter candle(s)
Claims (19)
1. An apparatus for gasifying carbon-containing material, comprising:
a gas generator; the gas generator having an upper region, a middle region, and a lower region; wherein the carbon-containing material is supplied to the upper region of the gas generator, oxygen is supplied to the middle region of the gas generator, and the carbon-containing material is largely gasified to a product gas in a fixed bed reactor in the lower region of the gas generator;
a hot gas filter, wherein the hot gas filter receives the product gas from the gas generator via a product gas line coupled to the lower region of the gas generator and passes the product gas through a filter assembly to yield a clean gas; the hot gas filter further including a solids outlet in a bottom region of the hot gas filter for taking off residual solids removed from the product gas by the filter assembly; and a gas line configured to supply oxygen to a middle region of the hot gas filter between the filter assembly and the solids outlet, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
a gas generator; the gas generator having an upper region, a middle region, and a lower region; wherein the carbon-containing material is supplied to the upper region of the gas generator, oxygen is supplied to the middle region of the gas generator, and the carbon-containing material is largely gasified to a product gas in a fixed bed reactor in the lower region of the gas generator;
a hot gas filter, wherein the hot gas filter receives the product gas from the gas generator via a product gas line coupled to the lower region of the gas generator and passes the product gas through a filter assembly to yield a clean gas; the hot gas filter further including a solids outlet in a bottom region of the hot gas filter for taking off residual solids removed from the product gas by the filter assembly; and a gas line configured to supply oxygen to a middle region of the hot gas filter between the filter assembly and the solids outlet, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
2. The apparatus of claim 1, wherein oxygen is supplied to the middle region of the gas generator in the form of air.
3. The apparatus of claim 1 or 2, wherein the carbon-containing material includes wood.
4. The apparatus of any one of claims 1 to 3, wherein the filter assembly includes one or more filter candles.
5. The apparatus of any one of claims 1 to 4, wherein the filter assembly is configured to remove solid particles not yet gasified, ash, and foreign bodies.
6. The apparatus of any one of claims 1 to 5, wherein oxygen is supplied to the middle region of the hot gas filter in the form of air.
7. The apparatus of any one of claims 1 to 6, wherein a draft in the product gas line is sufficiently strong that particles not gasified in the gas generator are transported substantially into the hot gas filter.
8. A method of gasifying carbon-containing material, comprising:
Date Recue/Date Received 2021-09-17 gasifying, in a gas generator, the carbon-containing material to a product gas;
passing the product gas to a hot gas filter having a filter assembly and a solids outlet for taking off residual solids removed from the product gas by the filter assembly;
passing the product gas through the filter assembly to yield a clean gas;
supplying, between the filter assembly and the solids outlet, oxygen to the product gas, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
Date Recue/Date Received 2021-09-17 gasifying, in a gas generator, the carbon-containing material to a product gas;
passing the product gas to a hot gas filter having a filter assembly and a solids outlet for taking off residual solids removed from the product gas by the filter assembly;
passing the product gas through the filter assembly to yield a clean gas;
supplying, between the filter assembly and the solids outlet, oxygen to the product gas, resulting in an additional gasification of residual constituents of the carbon-containing material present in the product gas received by the hot gas filter from the gas generator.
9. The method of claim 8, wherein the gas generator has an upper region, a middle region, and a lower region; wherein the carbon-containing material is supplied to the upper region of the gas generator, oxygen is supplied to the middle region of the gas generator, and the carbon-containing material is largely gasified to the product gas in a fixed bed reactor in the lower region of the gas generator.
10. The method of claim 9, wherein the oxygen supplied to the middle region of the gas generator in the form of air.
11. The method of any one of claims 8 to 10, wherein the carbon-containing material includes wood.
12. The method of any one of claims 8 to 11, wherein the filter assembly includes one or more filter candles.
13. The method of any one of claims 8 to 12, wherein the filter assembly is configured to remove solid particles not yet gasified, ash, and foreign bodies.
14. The method of any one of claims 8 to 13, wherein the oxygen is supplied to the product gas between the filter assembly and the solids outlet of the hot gas filter in the form of air.
15. The method of any one of claims 8 to 14, wherein a draft in the product gas passed from the gas generator to the hot gas filter is sufficiently strong that particles not gasified in the gas generator are transported substantially into the hot gas filter.
16. The method of any one of claims 8 to 15, wherein the hot gas filter receives the product gas from the gas generator via a product gas line coupled to a lowermost region of the gas generator.
17. The method of any one of claims 8 to 16, wherein the solids outlet is positioned Date Recue/Date Received 2021-09-17 in a bottom region of the hot gas filter.
18. The method of any one of claims 8 to 17, wherein supplying the oxygen to the product gas comprises supplying the oxygen via a gas line to a middle region of the hot gas filter between the filter assembly and the solids outlet.
19. The method of any one of claims 8 to 18, wherein the solids outlet is positioned in a bottom region of the hot gas filter.
Date Recue/Date Received 2021-09-17
Date Recue/Date Received 2021-09-17
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| CA2937445A CA2937445C (en) | 2016-07-28 | 2016-07-28 | Wood gasification |
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| CA2937445A CA2937445C (en) | 2016-07-28 | 2016-07-28 | Wood gasification |
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| CA2937445C true CA2937445C (en) | 2022-07-12 |
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| US11312914B2 (en) | 2019-02-04 | 2022-04-26 | Eastman Chemical Company | Gasification of plastics and solid fossil fuels to produce organic compounds |
| US11447576B2 (en) | 2019-02-04 | 2022-09-20 | Eastman Chemical Company | Cellulose ester compositions derived from recycled plastic content syngas |
| CN113646371A (en) | 2019-03-29 | 2021-11-12 | 伊士曼化工公司 | Polymers, articles and chemicals made from densified textile derived syngas |
| GR1010414B (en) | 2021-08-02 | 2023-02-24 | ΑΝΩΝΥΜΗ ΕΤΑΙΡΕΙΑ ΠΕΡΙΒΑΛΛΟΝΤΙΚΩΝ ΚΑΙ ΕΝΕΡΓΕΙΑΚΩΝ ΜΕΛΕΤΩΝ ΚΑΙ ΑΝΑΠΤΥΞΗΣ ΛΟΓΙΣΜΙΚΟΥ με δ.τ. ΕΜΙΣΙΑ Α.Ε., | Small-scale clean fuel production system using flexible fuel gasification |
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