JP2004149556A - Method for gasifying biomass and gasifying apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for gasifying biomass designed to treat a large amount of even the biomass having a relatively low specific gravity, to carry out a gasifying reaction at a relatively low temperature and having excellent productivity in producing a high-caloric gas and excellent properties of removing and treating toxic gases. <P>SOLUTION: The method for gasifying the biomass is carried out as follows. Biomass grains such as wood pieces or wood flour are fluidized in a fluid medium supporting a catalyst for gasifying organic components with an oxidizing gas to form a fluidized bed. The resultant fluidized bed is maintained at 400-600°C temperature so as to carry out the degrading gasification of the biomass. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to forest waste (wood fragments such as sawdust, wood powder, thinned wood, etc.) and agricultural waste (rice husk, rice straw, surplus products, etc.) generated in the manufacturing process of furniture and woodwork products. Biomass resources such as sewage and wastewater (contaminants, manure residue, sewage sludge, etc.) and low-grade coal are gasified at relatively low temperatures into hydrocarbons, hydrogen, CO, etc., and energy for cogeneration systems for power generation, etc. The present invention relates to a biomass gasification method and a gasification apparatus that can be provided as a source or a raw material gas of an organic synthetic product such as for fertilizer.
[0002]
[Prior art]
Techniques for converting biomass resources into energy and raw material gas include methods such as ethanol fermentation, methane fermentation, and heat gasification.The disadvantage of fermentation is that conversion takes time and practical operation is difficult. is there.
As the heating gasification technology applicable to biomass, coal gasification technology is basically followed, and from the shape of the gasification reactor, the following (1) fixed bed gasification method, (2) spouted bed gas And (3) fluidized bed gasification.
(1) Fixed bed gasification method
A fire bed (fire ladder) etc. for forming a fixed bed at the bottom of the furnace is provided, and enzymes and the like are charged and the biomass on the fixed bed is heated and gasified in a high-temperature atmosphere, and the ash discharged downward is discharged. It is a device designed to take out slugs, and there are the Torrax process and PUROX process developed in the United States for the purpose of gasifying municipal solid waste.
(2) Spouted bed gasification method
Pulverized coal or the like is pressurized by a dry pressurized feeder and gasified by spraying with oxygen and water vapor by a burner installed in the lower part of the furnace. Is being done.
(3) Fluidized bed gasification method
The fluidized bed is formed by gas supplied from the furnace bottom, and gasification is performed in the fluidized bed. A two-column fluidized bed gasifier (BCL) operating at a power plant in Burlington in the United States has a structure in which two circulating fluidized bed furnaces, a combustion tower and a gasification tower, are connected via a cyclone. This is an improved process so that sand as a fluid medium can be moved between two furnaces. In this process, air is introduced into one side, complete combustion of char and the like, and heating of the fluidized medium, and steam is introduced into the other side to gasify biomass. Since this process uses an indirect heating method, the calorific value (17.8 MJ / Nm) is about half that of natural gas than wood chips. ³ ) Is possible, and gas turbine power generation is performed using this high calorific value gas.
As related to this fluidized bed gasification system, for example, Patent Document 1 discloses that a part of a substance containing carbon is partially oxidized by a gas containing oxygen in a fluidized bed, and most of the substance containing carbon is gasified. Gasification with an agent such as water vapor, hydrogen, carbon monoxide or a mixed gas thereof and adding quicklime, and the partial pressure of carbon dioxide in the product gas in the fluidized bed is calculated from the partial pressure of decomposition of calcium carbonate at that temperature. A method of pyrolyzing or gasifying a substance containing carbon, which reacts quicklime with carbon dioxide while maintaining the pressure at a high level, is described.
Patent Document 2 discloses a reactor that gasifies biomass fuel to generate product gas, a combustion furnace that burns unburned components extracted together with a fluidized medium from the reactor and heats the fluidized medium with a fluidized bed. A gas-solid separator that separates and collects the heated fluid medium extracted together with the combustion exhaust gas from the furnace top of the combustion furnace and supplies the collected fluid medium to the reactor. A gasifier for biomass fuel gasification combined cycle power generation in which a boiler that uses combustion exhaust gas as a heat source is integrally provided and an auxiliary fuel supply unit that supplies auxiliary fuel to a fluidized bed portion of the combustion furnace is described. .
[0003]
[Patent Document 1]
JP-B-57-5840
[Patent Document 2]
JP-A-63-140805
[0004]
[Problems to be solved by the invention]
However, the above conventional technology has the following problems.
(1) In the fixed bed gasification method of gasifying biomass in a fixed bed, it can be effectively used only for biomass having a large specific gravity, and a gas containing a relatively large amount of tar and oil is generated, thereby decomposing the biomass. There was a problem that it became worse.
(2) In the spouted bed gasification method in which finely divided biomass is blown into a furnace, there is a problem that it is difficult to process a large amount of biomass having a low density and the productivity of gas generation is poor.
(3) The gasification method described in Patent Document 1 requires steam, hydrogen, carbon monoxide, and the like separately as a gasifying agent, and also requires that the partial pressure of carbon dioxide in the fluidized bed be maintained at a predetermined pressure or higher. Since the activity of quicklime itself cannot be sufficiently exerted, there has been a problem that operation is difficult in a small-scale power generation facility or the like.
(4) According to the fluidized-bed gasification method described in Patent Document 2, biomass is uniformly gasified in a fluidized bed to enable large-scale treatment. However, alkali components derived from biomass are contained in generated gas. Gas purification equipment, making it difficult to reduce the size of equipment and systems, and the versatility when applied to fuel gas generators such as small-scale power generation systems attached to woodworking plants. There was a problem that lacked.
(5) In the conventional gasification technology in which the temperature is as high as 800 ° C. to 1000 ° C., the partial oxidation reaction of hydrocarbon proceeds to CO and the amount of methane produced is reduced, so that the calorific value is reduced and contains an alkali component. There was a problem that handling of gas became difficult.
(6) Since the gasification reaction is at a high temperature, there are many restrictions on equipment such as heat resistance, and the heat recovery during the treatment is not appropriate, resulting in a low calorific value yield and a lack of economy.
(7) There is a problem that harmful substances such as SOx, NOx, dioxin, and environmental hormones are generated and cannot be treated efficiently.
(8) Although it is known that an alkali component serves as a gasification catalyst, it has a drawback that it deactivates a substrate containing a large amount of minerals such as coal.
[0005]
The present invention has been made in order to solve the above-mentioned problems, and it is possible to treat a large amount of biomass having a relatively small specific gravity, and to perform a gasification reaction at a relatively low temperature without deterioration of the catalytic function even in the presence of coal. It provides a high-calorie gas production method and a biomass gasification method that excels in the removal of harmful gases, and has a high performance with a low generation rate of alkali, tar, and oil in the generated gas. An object of the present invention is to provide a compact and highly versatile biomass gasification apparatus that does not require a gas purification facility, is easily miniaturized, and can be easily applied to a small-scale power generation system and the like.
[0006]
[Means for Solving the Problems]
The biomass gasification method according to claim 1, wherein the biomass particles such as wood pieces and wood powder and a fluid medium supporting an organic component gasification catalyst are fluidized with an oxidizing gas to form a fluidized bed, The fluidized bed is maintained at a temperature of 400 to 600 ° C. to gasify the biomass particles.
This configuration has the following operation.
(A) Since biomass particles are gasified on a fluidized medium carrying a gasification catalyst for an organic component (organic component gasification catalyst), a product gas with few impurities can be obtained, and a large-scale gas purification facility is required. Instead, it is possible to reduce the size of a power generation system or the like using the generated gas as fuel.
(B) Since the gasification reaction of the biomass particles is caused at a relatively low temperature, the partial oxidation reaction of the hydrocarbon does not proceed, so that the CO content does not increase significantly, and the methane content in the product gas does not increase. To ensure that the calorific value of the generated gas does not decrease.
(C) Since the alkali component in the biomass particles is trapped in the fluidized medium in the fluidized bed, it is possible to supply a product gas containing a small amount of alkali, to facilitate the handling and to improve the productivity.
(D) Since gasification is performed at a low temperature of 400 to 600 ° C., dust can be removed by a bag filter or a metal filter, and gas sent to the turbine can be purified by a simple method.
(E) Since biomass particles can be effectively used as fuel and a high calorie gas can be produced, the low-temperature fluidized-bed low-temperature catalytic gasification technology at a low temperature where methanation is dominant can be configured as a small system.
(F) When oxygen is added instead of air as an acid gas for this fluidization, a raw material gas for methanol synthesis can be produced, and the calorific yield is about 15-35% as compared with the conventional one. Can also be increased.
(G) Since the gas generation efficiency is excellent, a small and compact gasifier with a minimum unit size of about 1.5 t / day can be realized, and the gasifier and the gas turbine can be effectively utilized by utilizing the biomass resources dispersed in each factory. Alternatively, it can be applied as a cogeneration system using a fuel cell or the like, and is excellent in effective energy utilization.
(H) Since the fluidized-bed gasification method is applied, more uniform heat conduction than that by the fixed-bed gasification method is possible, and it can be applied to biomass particles having a low specific gravity. It has advantages such as less.
(I) Since harmful gases including SOx, NOx, dioxin, environmental hormones and the like generated during the treatment can be captured and removed by the fluid medium, they are excellent in environmental protection.
(J) By selecting biomass having a small content of mineral components such as coal and potassium as a main component, the alkali components in the biomass particles can be effectively utilized without being deactivated as a gasification catalyst. Therefore, high calorie gas can be generated with less impurities.
[0007]
Here, biomass grains are forest waste generated during the manufacturing process of furniture and woodwork products (wood fragments such as sawdust, wood powder, thinned wood, etc.), and agricultural waste (rice husk, rice straw, surplus products). Etc.), water and sewage waste (contaminants, manure residue, sewage sludge, etc.), low-grade coal, and the like.
The temperature of the fluidized bed for gasifying the biomass particles is desirably maintained at 400 to 600C, preferably 450 to 550C. This depends on the type and form of the biomass particles to be treated, the amount supplied per hour to be supplied to the fluidized bed apparatus, but as the temperature of the fluidized bed becomes lower than 450 ° C, the decomposition efficiency decreases extremely. As a result, unburned components such as tar and char increase and the productivity tends to decrease. Conversely, as the temperature exceeds 600 ° C., the partial oxidation reaction proceeds to increase the content of CO gas and decrease the calorific value. This is because a tendency appears, and these tendencies become lower when the temperature is lower than 400 ° C. or more than 600 ° C.
Examples of the gasifier equipped with a fluidized bed include: (1) an HTW process in which a bubbling-type fluidized bed in which potassium is not volatilized and a high pressure and high temperature are achieved in a conventional winkle furnace; and (2) a pressurized fluidized bed. The same or similar to the KRW process or the like in which a high-temperature portion is formed at an air charging portion of a fluidized-bed hearth portion and ash is locally burned and melted to achieve ash fusion / aggregation can be applied.
As the oxidizing gas, in addition to air, oxygen gas, air in which the content of oxygen gas is adjusted, high-temperature steam, or a mixed gas thereof can be used.
As the fluid medium, limestone, sand, or a mixture thereof can be applied.For example, an organic component gasification catalyst such as potassium is supported on the fluid medium by a method such as immersing particles of the fluid medium in a solution containing potassium. Can be used.
It is desirable that the particle size of the fluid medium is in the range of 0.5 to 50 mm, preferably 1 to 20 mm. This depends on the fluidization conditions, but as the particle size becomes smaller than 1 mm, the fluidity of the wood particles to form a fluidized bed tends to be poor, and as the particle size exceeds 20 mm, the biomass particles become more effective. This is because there is a tendency that the effective surface area required for causing a catalytic reaction by contacting with water decreases, and these tendencies become smaller when the thickness is smaller than 0.5 mm or larger than 50 mm.
[0008]
In the method for gasifying biomass according to claim 2, in the invention according to claim 1, the fluidized medium is a granular material containing calcium carbonate and / or calcium oxide, and the organic component gasification catalyst is potassium or the like. It is constituted so that it may be alkali content of.
With this configuration, the following operation is obtained in addition to the operation described in the first aspect.
(A) A contact gasification reaction by an alkali component such as an alkali metal salt can be used. Alkali metal salts, especially potassium salts, show high activity in gasification reactions of coal, char, carbon, graphite and the like. That is, the alkali oxide forms a complex with carbon, is reduced to an alkali metal by elimination of CO, and is catalyzed by repeating a redox cycle of an alkali metal-alkali metal oxide oxidized by oxygen in a gas phase. Can be effectively advanced.
(B) The potassium content in the woody biomass particles contained in the generated gas and dissipated in the conventional high-temperature gasification method is reduced by a fluid medium composed of calcium carbonate or calcium oxide at an operating temperature of 500 to 600 ° C. It can be efficiently adsorbed and captured, and can be reused as an organic component gasification catalyst.
(C) Since the alkali metal can be completely captured by allowing the fluid medium supporting the catalyst to be present in the reaction furnace, the gasification efficiency can be maintained at a high level without replenishing or replacing the catalyst.
(D) Since the potassium content in the wood is adsorbed and captured by the fluid medium particles, the potassium content can be recovered and reused in the soil as potassium fertilizer or the like.
(E) Since the chlorine compound in the wood is captured as calcium chloride by the calcium compound, generation of dioxin can be prevented. In addition, even if a gas containing an environmental hormone is generated during the processing of the biomass particles, the gas can be removed by adsorbing the gas on the fluid medium.
(F) Since the fluidized medium is a granular material containing calcium carbonate and / or calcium oxide, it is possible to effectively capture harmful substances such as sulfur and dioxin generated during the treatment and obtain a purified product gas. Can be.
(G) The gasification reaction temperature can be set low by supporting the gasification reaction catalyst of woody biomass particles on a medium for a fluidized reaction device having a predetermined specific gravity and particle size while maintaining its high activity, thereby saving energy. Methane in the product gas can be produced at a higher concentration, and the calorific value of the generated gas can be increased.
(H) Potassium, which is an alkali component in wood, can be effectively used as an organic component gasification catalyst that promotes the decomposition of tar, char, and the like.
(I) Combination with a flow reactor capable of increasing the number of reaction stages makes it possible to reduce the size and size of the device itself.
[0009]
Here, the alkali content in the fluid medium is desirably in the range of 0.05 to 10% by mass, preferably 1 to 5% by mass. This depends on the form and type of the biomass particles to be treated, but as the alkali content acting as the organic component gasification catalyst becomes less than 1% by mass, the harmful substance trapping efficiency and the decomposition gasification efficiency decrease. On the contrary, as the content exceeds 5% by mass, there is a tendency that alkalis are released into the product gas to cause adverse effects such as the necessity of gas purification treatment, and these tendencies become less than 0.05% by mass. , Or more than 10% by mass.
[0010]
The method for gasifying biomass according to claim 3 is the method according to claim 2, wherein the biomass particles are heated in a fluidized state in the fluidized bed to remove alkali components such as potassium contained in the biomass particles. It is configured to be volatilized and loaded on the fluid medium.
This configuration has the following operation in addition to the operation of the second aspect.
(A) Potassium contained in biomass particles is efficiently captured by a fluid medium such as calcium carbonate or calcium oxide, and the fluid medium carrying potassium can be effectively used as an organic component gasification catalyst.
(B) Potassium, which was volatilized and dissipated in the generated gas and could not be used in the conventional high-temperature gasification method, can be effectively recovered.
Here, potassium hydroxide, potassium carbonate, or the like can be used as a potassium source that is an alkali component.
[0011]
The method for gasifying biomass according to claim 4 is the invention according to claim 3, wherein the fluidized medium taken out from the bottom of the fluidized bed is cooled to become an alkali-containing fertilizer such as a potassium fertilizer. Have been.
This configuration has the following operation in addition to the operation of the third aspect.
(A) High-temperature potassium-containing ash discharged from an ash discharge unit provided at the bottom of a fluidized bed in which a fluidized bed is formed can be rapidly cooled to promote vitrification. The alkali content can be stably retained by the glass content in the ash, and a fertilizer excellent in retention of the alkali content such as potassium can be provided.
(B) The gasifier can be used as a device for producing an alkali-containing fertilizer such as a potassium fertilizer, and is excellent in productivity as a system.
(C) Alkaline-containing fertilizers such as potassium fertilizers can be produced at the same time as gasification of biomass particles, so that energy and resources can be effectively used.
[0012]
According to a fifth aspect of the present invention, there is provided the biomass gasification method according to the first aspect of the present invention, wherein the harmful gas containing chlorides such as SOx, NOx, dioxin and the like, and organic substances such as environmental hormones generated in the fluidized bed is used as the fluid medium To be adsorbed and trapped in a fluid stirring state.
This configuration has the following operation in addition to the operation of the first aspect.
(A) Since the harmful gas generated during the gasification of the biomass particles is trapped on the surface of or inside the particles of the flowing medium in which the harmful gas flows and diffuses, the influence on the surrounding environment due to the release or leakage of the harmful gas is suppressed. Excellent in environmental protection.
(B) Since the harmful gas is removed when the biomass particles are gasified, the treatment in the subsequent gas treatment step is facilitated, and the overall treatment cost can be reduced and the economy is excellent.
Here, in order to efficiently capture the harmful gas in the fluid medium, it is preferable that the oxygen concentration in the atmosphere gas be in the range of 0 to 20%, preferably 5 to 10% in the fluid combustion state. This depends on the type of harmful gas adsorbed on the fluid medium and the particle size and surface area of the fluid medium, but as the oxygen concentration becomes lower than 5%, the gasification by oxidation or decomposition of biomass tends to be insufficient. This is because, as it becomes higher than 10%, the calorific value of the generated gas tends to decrease, and when it becomes more than 20%, it becomes more remarkable.
Further, the pressure of the atmospheric gas is preferably in the range of 0.01 to 1.0 Pascal, preferably 0.1 to 0.3 Pascal. This depends on the type of generated gas, combustion temperature, oxygen concentration, etc., but as the pressure becomes lower than 0.1 Pascal, the trapping efficiency in the fluid medium tends to decrease, and conversely, from 0.3 Pascal. This is because the higher the pressure, the more difficult it becomes to inject gas to form a fluidized bed, and these tend to be more remarkable when the pressure is lower than 0.01 Pascal or higher than 1.0 Pascal.
[0013]
The method for gasifying biomass according to claim 6 is the method according to any one of claims 1 to 5, wherein the biomass particles (A) and the fluid medium (B) loaded on the fluidized bed are provided. Is configured so that the mass ratio (A / B) to the above is 1/100 to 1/2.
With this configuration, the following operation is provided in addition to the operation described in any one of the first to fifth aspects.
(A) Since the mass ratio between the biomass particles and the fluidized medium in the fluidized bed is set in a specific range, the biomass particles composed of wood pieces and the like can be uniformly and effectively stirred in the fluidized bed.
(B) Since the fluidized state is appropriately maintained, the control of the partial oxidation reaction of hydrocarbons is facilitated, and the amount of low molecular weight hydrocarbons generated by reducing CO generation is improved, and the calorific value of generated gas is improved. Can be.
Here, the mass ratio (A / B) between the biomass particles and the fluid medium supplied to the fluidized bed is preferably in the range of 1/100 to 1/2, preferably 1/50 to 1/10.
This depends on the form of the biomass granules, but as the mass ratio (A / B) becomes smaller than 1/50, the treatment efficiency of the biomass granules tends to be extremely reduced. The gasification efficiency tends to decrease because the fluidized state of the biomass particles becomes non-uniform, and these tendencies occur when the mass ratio (A / B) becomes smaller than 1/100 or exceeds 1/2. This is because it becomes more noticeable.
[0014]
According to a seventh aspect of the present invention, in the method for gasifying biomass according to any one of the first to sixth aspects, a part of the gas obtained by gasifying the biomass particles is extracted from the fluidized bed to recover heat. After the treatment and / or the dust removal treatment, a gas circulation adjustment step of circulating the fluidized bed is provided.
With this configuration, the following operation is provided in addition to the operation of any one of the first to sixth aspects.
(A) Since it has a gas circulation adjusting step of processing and circulating a part of the product gas in which the biomass particles are decomposed, the controllability of adjusting the amount of circulating gas according to the fluidized state of the fluidized bed is excellent. In addition, the gasification conditions of the biomass particles are constantly maintained appropriately, and a large amount of purified gas containing less impurities such as tar and char can be produced, and the productivity is excellent.
(B) A part of the gas obtained by gasifying the biomass particles from the fluidized bed can be taken out, subjected to a dust removal treatment, and circulated and supplied to the fluidized bed. , And can be easily operated with enhanced gasification efficiency.
(C) Since heat can be recovered from a part of the generated gas, heat loss is reduced and the economy is excellent.
Here, the ratio (C / D) of the circulating gas amount (C) circulated through the fluidized bed to the total gas amount (D) discharged from the fluidized bed is 1/10 to 1/2, preferably 1 /. It is desirable to set the range of 5 to 1/3. This depends on the application conditions such as the temperature and volume of the fluidized bed, the amount of biomass particles processed, and the amount of fluidized medium supplied, but as the amount of circulating gas becomes smaller than 1/5 of the total amount of exhaust gas, the heat recovery efficiency and The dust removal efficiency tends to decrease and the operating state tends to deteriorate. As the ratio exceeds 1/3, the capacity of the air supply system such as a pump and a fan for circulating the circulating gas becomes excessive and the workability deteriorates. This is because tendencies appear, and these tendencies become smaller than 1/10 or become more pronounced when they exceed 1/2.
[0015]
In the biomass gasifier according to claim 8, the biomass particles such as wood pieces and wood powder are supplied from the body wall of the biomass via a biomass supply pipe, and the carbon dioxide is loaded with an organic component gasification catalyst such as potassium. A fluidized bed section that holds a fluidized medium such as calcium or calcium oxide and forms a fluidized bed composed of the biomass particles and the fluidized medium by an oxidizing gas supplied through a fluidizing gas supply pipe provided at the bottom thereof. And a fluidized bed heating section disposed surrounding the fluidized reaction vessel, and an ash discharge section provided at the bottom of the fluidized bed section for discharging the ash after the biomass particle decomposition is provided. A heat recovery unit and / or a dust removal unit that performs heat recovery and / or dust removal of a product gas obtained by decomposing the biomass particles discharged from an upper portion of the fluidized bed unit; and a product gas that is subjected to heat recovery and dust removal. The fluidized bed section It is configured by a gas circulation adjuster for circulating the bottom.
This configuration has the following operation.
(A) Since the biomass gasifier has a fluidized bed formed by an oxidizing gas, a fluidized bed composed of a biomass particle and a fluidized medium carrying an organic component gasification catalyst, the gas of the biomass particle can be produced even at a low temperature. It is possible to suppress the partial oxidation reaction of hydrocarbons, secure the methane content in the product gas, and effectively prevent the calorific value of the product gas from decreasing.
(B) Since the fuel gas obtained by gasification of the biomass particles is applied to a small generator to generate electric power, the circulating gas in the fluidized bed and the exhaust gas from the generator can be heat-recovered as low-pressure steam. Improve overall thermal efficiency with cogeneration systems such as heat sources and factory process steam supply.
(C) The alkali component in the biomass particles is captured in the fluidized medium in the fluidized bed, and a product gas with a small amount of alkali can be supplied, the handling thereof is facilitated, and the productivity and workability are excellent.
(D) Since it has a fluidized bed heating section disposed around the fluidized bed section, it has excellent controllability for controlling the temperature in the fluidized bed in which the gasification reaction is performed and heat utilization efficiency, and always has a predetermined gas component. The product gas adjusted to the range can be efficiently produced.
(E) Since it has a heat recovery unit that recovers heat of the generated gas and a dust removal processing unit that removes solid particles in the generated gas using a filter such as a bag filter or a ceramic filter, the thermal efficiency of the system can be improved. By removing dust from the exhaust gas, the environmental protection can be enhanced.
(F) By operating a gas circulation adjusting section for circulating gas in the fluidized bed section and a fluidized bed heating section for adjusting the temperature of the fluidized bed section in cooperation with each other, flow conditions such as temperature and flow rate in the fluidized bed can be controlled. By controlling, the generation efficiency and heat efficiency of the generated gas can be increased and the operation can be performed efficiently.
(G) Since high-calorie, low-tar, char and other gas can be produced using biomass particles as fuel, subsequent exhaust gas treatment can be facilitated, and gas purification equipment can be omitted or reduced in size, and a small system can be configured.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
A gasification apparatus to which the biomass gasification method according to Embodiment 1 of the present invention is applied will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of the biomass gasifier of the first embodiment.
In FIG. 1, reference numeral 10 denotes a gasifier according to the first embodiment, 11 denotes a fluidized reaction tank for holding and fluidizing biomass particles such as wood pieces and a fluid medium, 11a denotes a fluidized bed of the fluidized reaction vessel 11, 12 is a biomass supply pipe for continuously supplying biomass granules from a hopper (not shown) to the fluidized bed 11a, 13 is a fluidized bed heating unit arranged around the substantially cylindrical fluidized reaction tank 11, Reference numeral 14 denotes an ash discharge unit provided at the bottom of the fluidized bed unit 11a for discharging ash after biomass granule decomposition, 15 denotes a dust removal unit provided with a filter for removing dust from the circulated product gas, and 16 Is a circulating gas heat recovery unit for recovering the heat of the product gas taken out from the fluidized bed unit 11a, and 17 is a product gas taken out from the upper part of the fluidized bed unit 11a and sent to the dust removal processing unit 15 and the heat recovery unit 16 for fluidization. Circulates to the bottom of floor 11a A gas circulation path, 17a is a blower disposed in the gas circulation path 17, 18 is a fluidized bed heat recovery section for directly recovering heat from inside the fluidized bed section 11a, and 19 is an outer shell of the main body of the gasification apparatus 10. Oxidizing gas supply unit for supplying an oxidizing gas (air) to the oxidizing gas and supplying an oxidizing gas such as air for forming a fluidized bed in the fluidized bed 11a, and 19a flows the oxidizing gas in the outer shell of the main body. A fluidizing gas supply pipe 20 is supplied to the floor 11a and fluidized, and a fluidized gas supply pipe 20 takes out a product gas as a product gas from a gas circulation adjustment unit including a dust removal processing unit 15, a heat recovery unit 16, a gas circulation path 17, and a blower 17a. Gas discharge pipe 21 for the outside of the body of the gasifier 10 in which the fluidized bed portion 11a, the fluidized bed heating portion 13, the ash discharge portion 14 and the like are built in and the internal pressure is adjusted to 0.1 to 0.3 Pascal. It is a shell.
[0017]
The fluid medium is a medium for impregnating limestone or the like with a potassium hydroxide solution having a concentration of, for example, 0.1 to 30% to carry an organic component gasification catalyst, thereby realizing a low-temperature gasification process. The generation of components is suppressed, and the exhaust gas treatment equipment accompanying these treatments is omitted or reduced in capacity, and the gasification efficiency is improved.
Alkali metal salts, especially potassium salts, show high activity in gasification reactions of coal, char, carbon, graphite and the like. It is said that the catalytic reaction proceeds by forming a complex of the alkali oxide with carbon, reducing CO to the alkali metal by elimination, and repeating a reduction oxidation cycle by oxidation of the alkali metal in the gas phase. .
The heat recovery unit 16 for the circulating gas and the fluidized bed heat recovery unit 18 supply water as a heat medium, heat the water with the heat of the generated gas or the gas in the fluidized bed, and recover it as steam or high-temperature water. It is a vessel.
The fluidized bed heating unit 13 is a device provided with an electric heater. The fluidized bed heating unit 13 and the gas circulation adjusting unit can be controlled to a predetermined temperature of 400 to 600 ° C. based on temperature data obtained from a sensor (not shown) that measures the temperature in the fluidized bed 11a. It has become.
[0018]
A biomass gasification method applied to the biomass gasifier 10 configured as described above will be described.
First, a fluid medium such as limestone, dolomite, and magnesia supporting a predetermined amount of potassium is supplied into the fluidized bed 11a, and the oxidizing gas is supplied through a compressor, an air chamber, a mass flow, etc. of the oxidizing gas supply unit 19. Is supplied and fluidized. Next, the biomass particles crushed to a predetermined particle size are supplied to the fluidized bed portion 11a through the biomass supply pipe 12, and a fluidized bed is formed by the biomass particles and the fluidized medium. Heating can be performed via the fluidized bed heating unit 13 or the like to promote partial oxidation of the biomass particles, thereby promoting decomposition gasification. Further, while continuously supplying the biomass particles at a predetermined supply amount, the gasification is advanced, and the circulating gas is circulated into the fluidized reaction tank 11 via the gas circulation adjusting unit. In this way, the product gas is taken out from the gas circulation adjusting unit via the product gas discharge pipe 20, and the operating state is constantly maintained so that the temperature in the fluidized bed 11a falls within a predetermined range.
[0019]
Next, the role of the fluid medium and the catalytic action in the reduction oxidation process in the fluidized bed will be described.
FIG. 2 is a schematic diagram showing the role of a fluid medium and the catalytic action in such a reduction oxidation process in a fluidized bed.
As shown, biomass particles such as wood are fluidized in a fluidized bed with a fluid medium at 400-600 ° C. Thus, K, K adhered to the surface of particles such as carbon (Cabon) ₂ O, K ₂ CO ₃ Containing CaCO ₃ / CaO to promote the gasification reaction by this catalytic action, ₂ , CH ₄ , CO ₂ And discharge it to the outside of the system. On the other hand, residual ash containing potassium and lime can be discharged and collected from below.
As shown in the figure, the catalytic gasification reaction includes (1) C-CO ₂ Reaction, (2) CO ₂ Reaction, (3) CH ₂ O-reaction, which involves the decomposition and gasification of wood pieces, tar, and char by means of CaCO2 carrying potassium and floating in a fluidized bed. ₃ / CaO particles can effectively proceed on the surface.
That is, as shown in FIG. 2, in such reaction processes (1) to (3), first, K ₂ CO ₃ Is K ₂ O and CO ₂ Decompose into Next, the generated K ₂ CO in atmosphere such as O ₂ And O ₂ , H ₂ K is generated by a recycling reaction in which redox is repeated between O and O. This K is O ₂ And CO ₂ Oxidized by K ₂ O or K ₂ CO ₃ As a fluid medium as a catalyst for ₃ / Formed on the surface of CaO particles and the like.
In the conventional wood gasification method, the reaction temperature is as high as around 1000 ° C., so that alkalis such as potassium contained in wood are reduced to metal and sublimated and discharged together with the generated gas. There were also many restrictions on gas utilization. However, since the gasification method according to the present embodiment is a low-temperature gasification reaction at a temperature of 600 ° C. or less, the alkali metal concentration in the product gas is greatly reduced, and a large amount of the alkali metal remains on the fluidized medium to produce a gasification catalyst for tar and char components It became clear that the function as can be fully utilized.
In addition, the presence of a suitable carrier such as calcium oxide in the reactor can completely capture the alkali metal, so that the gasification efficiency can be maintained at a high level without replenishment or replacement of the catalyst. Further, it has been clarified that the apparatus for purifying generated gas, which requires complicated maintenance, is suitable for a small gasification system that can be simplified.
[0020]
(Example)
CO in the carrier gas (oxidizing gas) at 450 ° C in the fluidized bed ₂ As a result of examining the catalytic effect of potassium salt from the weight loss of biomass particles and charcoal at an air ratio of 4/1, the gasification rate of the residue after pyrolysis was reduced in biomass particles by adding potassium salt. It was confirmed that it promoted. In particular, the difference was more remarkable in the gasification of charcoal, and it became clear that the gasification rate was greatly enhanced.
During low-temperature gasification, heavy hydrocarbons such as tar and char and char may be produced during the reaction, and potassium carbonate was found to be an effective catalyst as a gasification catalyst for these tar and char.
Fluidized bed temperature 550 ° C, CO ₂ / O ₂ In a gasification experiment of graphite, which is a difficult gasification substance, at a ratio of 1/1, it was found that the gasification rate was improved from 15% to 85% by the addition of a KOH catalyst. Further, the perovskite-supported potassium carbonate catalyst has a gas conversion rate of 450 ° C. in a fluidized bed at a low oxygen concentration of about 4 vol%, which is lower than that of potassium carbonate impregnated carbon. Was greatly improved from 2.3% to 98%.
Here, it was found that the role of perovskite was to activate and reduce the potassium salt and to capture the potassium salt with high efficiency, and the amount of catalyst loss after the reaction could be greatly reduced to 4% compared to 17% of the carbon-supported catalyst.
In order to achieve complete gasification at a low temperature, tar to be generated, gasification of a char component with high efficiency, and gasification at a low temperature of 600 ° C. or less by using a catalyst component capable of high efficiency contact gasification, This gasification method using potassium catalyst was found to be an effective method to obtain combustion gas from biomass with high efficiency.
[0021]
Since the biomass gasification method and the gasification apparatus of the first embodiment are configured as described above, they have the following operations.
(A) Since the fluidized bed composed of the fluid medium and the biomass particles supporting the organic component gasification catalyst has the fluidized bed portion 11a formed by the oxidizing gas, the gasification reaction of the biomass particles can be efficiently performed even at a low temperature. This can suppress the partial oxidation reaction of hydrocarbons, secure the methane content in the product gas, and effectively prevent the calorific value of the product gas from decreasing.
(B) Since biomass particles are decomposed and gasified in a fluid medium carrying an organic component gasification catalyst, a product gas with few impurities can be obtained, and a large-scale gas purification facility is not required. A power generation system or the like using fuel can be miniaturized.
(C) The heat is recovered as low-pressure steam from the fluidized bed section 11a and the circulating gas, and the overall thermal efficiency can be improved by a cogeneration system such as steam supply in a factory process.
(D) Since part of the biomass-producing gas is processed and circulated, the controllability of adjusting the amount of circulating gas according to the fluidized state of the fluidized bed is excellent, and the conditions for decomposing and gasifying biomass particles are appropriately adjusted. Can be maintained.
(E) By performing dust removal processing of the generated gas in the dust removal processing unit 15 provided with the filter, the inside of the fluidized bed composed of the biomass particles and the fluidized medium can be maintained under appropriate conditions, and the decomposition gasification efficiency is enhanced. Can be easily operated.
(F) Since the circulating gas heat recovery section 16 is provided and heat can be recovered from a part of the generated gas, heat loss is reduced and the economy is excellent.
(G) Since the fluidized bed heating section 13 is provided so as to surround the fluidized reaction tank 11, the temperature control in the fluidized bed in which the gasification reaction is performed is excellent, and the production is always adjusted to a predetermined gas component range. Gas can be produced efficiently.
(H) Since the alkali component in the biomass particles can be captured in the fluidized medium in the fluidized bed, not only can the catalytic effect in the gasification furnace be improved, but also a product gas with a small alkali content can be supplied, and the handling thereof can be improved. It is easy and has excellent gas productivity and workability.
(I) A contact gasification reaction by an alkali component such as an alkali metal salt can be used. Alkali metal salts, especially potassium salts, show high activity in gasification reactions of coal, char, carbon, graphite and the like.
(J) Since the alkali metal can be completely captured by allowing the fluid medium supporting the catalyst to be present in the reaction furnace, the gasification efficiency can be maintained at a high level without replenishment or replacement of the catalyst.
(K) Since the gasification is performed at a low temperature of 400 to 600 ° C., dust can be removed by a bag filter and a metal filter, and the gas sent to the turbine can be purified by a simple method.
(L) When oxygen is used as the acid gas, a raw material gas for methanol synthesis can be produced, and the calorific yield can be increased by about 15 to 35% as compared with the conventional case.
(M) Since the fluidized-bed gasification method is applied, more uniform heat conduction is possible than in the fixed-bed gasification method, and the invention can be applied to biomass particles having a low specific gravity.
(N) Since the fluid medium is a granular material containing calcium carbonate and / or calcium oxide, it effectively traps harmful substances such as sulfur, chlorine compounds, and dioxins generated during processing, and purifies the purified gas. Obtainable.
(O) Since the potassium content in the wood used as the organic component gasification catalyst is captured in the ash, the ash can be recovered and used as potassium fertilizer or the like in the soil.
(P) The gasification reaction temperature can be set low by supporting the woody biomass particle gasification reaction catalyst on the fluidized reaction medium (specific gravity or particle size) while maintaining its high activity.
(Q) By operating a gas circulation adjusting section for circulating gas in the fluidized bed section and a fluidized bed heating section for adjusting the temperature of the fluidized bed section in cooperation with each other, flow conditions such as temperature and flow rate in the fluidized bed can be controlled. By controlling, the generation efficiency and heat efficiency of the generated gas can be increased and the operation can be performed efficiently.
(R) Since the internal pressure of the outer shell 21 of the main body can be set to be higher than the atmospheric pressure, the internal air is supplied to the fluidized bed to increase the thermal efficiency, and at the same time to improve the maintainability of the apparatus and the gas amount. Excellent controllability.
[0022]
(Embodiment 2)
A gasification apparatus to which the biomass gasification method according to Embodiment 2 of the present invention is applied will be described with reference to the drawings.
FIG. 3 is a schematic configuration diagram of the biomass gasifier of the second embodiment.
In FIG. 3, reference numeral 30 denotes a gasifier of the second embodiment, 31 denotes a fluidized bed portion of a fluidized reaction vessel 31a for holding a fluidized medium carrying an organic component gasification catalyst and supplying and fluidizing biomass particles, 32 Is a lock hopper for holding biomass particles at a predetermined pressure in a pressure vessel 34 connected to an external hopper 33 for storing biomass particles and having an internal pressure adjusted to 0.1 to 0.3 Pascal, and 35 is a lock hopper. A biomass supply pipe for supplying the biomass particles in 32 to the fluidized bed section 31, a fluidized bed heating section 36 for surrounding and heating the fluidized bed section 31, and a 37 provided at the bottom of the fluidized bed section 31. An ash discharge section 38 from which ash after biomass granule decomposition is discharged is supplied with exhaust gas taken out from the upper part of the fluidized bed section 31 to recover a part of the unburned portion in the exhaust gas and return it to the fluidized bed section 31 while producing it. A cyclone 39 discharges gas from the center of the ceiling, 39 is a dust removing section provided with a bag filter or the like for filtering a generated gas taken out from the cyclone 38, and 40 is a pressurized air and a generated gas which are supplied. (Combustor) for mixing and combusting to generate combustion gas, 41 is driven by a gas turbine 41a driven by the supply of the combustion gas pressurized by the combustor 40 and a drive shaft of the gas turbine 41a. A power generation device including a compressor 41b that takes in and pressurizes and supplies external air to the bottom of the fluidized bed portion 31 and a generator 41c driven by a gas turbine 41a. Reference numeral 42 denotes a product gas or the like from the gas turbine 41a. A combustion gas discharge pipe 43 is taken out as a fuel gas discharge pipe 43 and is arranged to be branched from the combustion gas discharge pipe 42 so that a part of the combustion gas is A circulating gas branch pipe 44 for supplying and fluidizing the biomass particles and the fluid medium is disposed as necessary and takes out a part of the combustion gas discharged from the dust removal processing section 39 and returns it to the fluidized bed section 31. A combustion gas adjusting pipe 45 for supplying the compressed air by the compressor 41b to the bottom (pressure vessel 34) of the fluidized bed 31 is provided with a compressed air supply pipe 46, and a compressed air supply pipe 46 is provided branched from the compressed air supply pipe 45. It is a compressed air branch pipe for supplying a part of the compressed air to the combustor 40.
[0023]
The biomass gasifier according to the second embodiment is different from the biomass gasifier of the second embodiment in that a power generation device 41 including a gas turbine 41a, a compressor 41b, and a power generator 41c is incorporated in a part of a system of a gas circulation adjustment unit. Different from one.
An operation method of the biomass gasifier 30 configured as described above will be described. First, a fluid medium made of limestone carrying potassium is supplied into the fluidized bed 31. Next, air, which is an oxidizing gas, is supplied and fluidized through a starting compressor (not shown). Next, the biomass particles crushed to a predetermined particle size are supplied to the fluidized bed section 31 via the external hopper 33 and the lock hopper 32 to form a fluidized bed with the biomass particles and the fluidized medium.
At this time, the inside of the fluidized bed section 31 where the fluidized bed is formed is heated via the fluidized bed heating section 36 and the like to advance the partial oxidation of the biomass grains, and the biomass grains are continuously supplied at a predetermined supply amount, and the combustion is performed. The gas whose flow rate, pressure, oxygen concentration and the like are adjusted by the gas adjusting pipe 44 and the circulating gas branch pipe 43 is circulated in the fluidized bed 31. In this way, the combustor 40 can also extract unburned gas containing methane, carbon monoxide, carbon dioxide, and the like from the combustion gas discharge pipe 42 as product gas. In addition, the operating state can be constantly maintained so that the temperature in the fluidized bed section 31 falls within a predetermined range. On the other hand, the combustion gas discharged through the cyclone 38 is mixed and combusted with preheated air containing a part of the combustion gas heated and compressed by the combustor 40 to drive the gas turbine 41a.
Thus, the drive shafts of the generator 41c and the compressor 41b are moved, so that external air intake and predetermined power supply can be simultaneously and efficiently performed.
As in the case of the first embodiment, a fluidized bed heat recovery unit including a coil-shaped heat exchanger (not shown) for directly recovering heat from the fluidized bed unit 31 is provided. It is also possible to recover the combustion heat generated in the inside 31 or to maintain the inside of the fluidized bed at a predetermined temperature.
[0024]
Since the biomass gasification method of the second embodiment is configured as described above, it has the following operation in addition to the operation of the first embodiment.
(A) The organic component gasification catalyst is carried on the fluidized medium in the fluidized bed section 31 to obtain a combustion gas of a predetermined concentration, and the gas turbine 41a and the compressor 41b using the combustion gas as a driving source are integrated. Since the power generation device 41 is configured, the entire power generation device 41 can be reduced in size and a relatively small power generation system can be constructed.
(B) It is possible to adjust the oxygen gas concentration by returning a part of the combustion gas taken out of the dedusting processing section 39 using the combustion gas adjusting pipe 44 to the fluidized bed section 31 without passing through the combustor 40, The controllability of the gasifier 30 is excellent. That is, since the oxygen concentration in the combustion gas from the dedusting processing section is lower than the gas discharged from the combustor 40, the oxygen concentration in the furnace can be reliably reduced, thereby supplying the oxygen to the fluidized bed section 31. The oxygen gas concentration in the gas can be adjusted effectively.
[0025]
【The invention's effect】
According to the biomass gasification method of the first aspect, the following effects are obtained.
(A) Since biomass particles are gasified on a fluidized medium carrying a gasification catalyst for an organic component (organic component gasification catalyst), a product gas with few impurities can be obtained, and a large-scale gas purification facility is required. Instead, it is possible to reduce the size of a power generation system or the like using the generated gas as fuel.
(B) Since the gasification reaction of the biomass particles is caused at a relatively low temperature, the partial oxidation reaction of the hydrocarbon does not proceed, so that the CO content does not increase significantly, and the methane content in the product gas does not increase. To ensure that the calorific value of the generated gas does not decrease.
(C) Since the alkali component in the biomass particles is trapped in the fluidized medium in the fluidized bed, it is possible to supply a product gas containing a small amount of alkali, to facilitate the handling and to improve the productivity.
(D) Since the gasification is performed at a low temperature, dust can be removed by a bag filter and a metal filter, and the gas sent to the turbine can be purified by a simple method.
(E) Since biomass particles can be effectively used as fuel and a high calorie gas can be produced, the low-temperature fluidized-bed low-temperature catalytic gasification technology at a low temperature where methanation is dominant can be configured as a small system.
(F) When oxygen is added instead of air as an acid gas for this fluidization, a raw material gas for methanol synthesis can be produced, and the calorific yield is about 15-35% as compared with the conventional one. Can also be increased.
(G) Since the gas generation efficiency is excellent, a small and compact gasifier with a minimum unit size of about 1.5 t / day can be realized, and the gasifier and the gas turbine can be effectively utilized by utilizing the biomass resources dispersed in each factory. Alternatively, it can be applied as a cogeneration system using a fuel cell or the like, and is excellent in effective energy utilization.
(H) Since the fluidized-bed gasification method is applied, more uniform heat conduction than that by the fixed-bed gasification method is possible, and it can be applied to biomass particles having a low specific gravity. It has advantages such as less.
(I) Since harmful gases including SOx, NOx, dioxin, environmental hormones and the like generated during the treatment can be captured and removed by the fluid medium, they are excellent in environmental protection.
(J) By selecting biomass having a small mineral content and potassium as a main component, the alkali component in the biomass particles can be effectively used without deactivating the alkali component as a gasification catalyst to reduce impurities. It can produce less high calorie gas.
[0026]
According to the biomass gasification method of the second aspect, the following effects are obtained in addition to the effects of the first aspect.
(A) A contact gasification reaction by an alkali component such as an alkali metal salt can be used. Alkali metal salts, especially potassium salts, show high activity in gasification reactions of coal, char, carbon, graphite and the like. That is, the alkali oxide forms a complex with carbon, is reduced to an alkali metal by elimination of CO, and is catalyzed by repeating a redox cycle of an alkali metal-alkali metal oxide oxidized by oxygen in a gas phase. Can be effectively advanced.
(B) Efficient adsorption and capture by reacting the potassium content in the woody biomass particles contained in the generated gas and dissipated in the conventional high temperature gasification method with a fluid medium composed of calcium carbonate and calcium oxide. It can be reused as an organic component gasification catalyst.
(C) Since the alkali metal can be completely captured by allowing the fluid medium supporting the catalyst to be present in the reaction furnace, the gasification efficiency can be maintained at a high level without replenishing or replacing the catalyst.
(D) Since the potassium content in the wood is adsorbed and captured by the fluid medium particles, the potassium content can be recovered and reused in the soil as potassium fertilizer or the like.
(E) Since the chlorine compound in the wood is captured as calcium chloride by the calcium compound, generation of dioxin can be prevented. In addition, even if a gas containing an environmental hormone is generated during the processing of the biomass particles, the gas can be removed by adsorbing the gas on the fluid medium.
(F) Since the fluidized medium is a granular material containing calcium carbonate and / or calcium oxide, it is possible to effectively capture harmful substances such as sulfur and dioxin generated during the treatment and obtain a purified product gas. Can be.
(G) The gasification reaction temperature can be set low by supporting the gasification reaction catalyst of woody biomass particles on a medium for a fluidized reaction device having a predetermined specific gravity and particle size while maintaining its high activity, thereby saving energy. Methane in the product gas can be produced at a higher concentration, and the calorific value of the generated gas can be increased.
(H) Potassium, which is an alkali component in wood, can be effectively used as an organic component gasification catalyst that promotes the decomposition of tar, char, and the like.
(I) Combination with a flow reactor capable of increasing the number of reaction stages makes it possible to reduce the size and size of the device itself.
[0027]
According to the biomass gasification method of the third aspect, the following effect is obtained in addition to the effect of the second aspect.
(A) Potassium contained in biomass particles is efficiently captured by a fluid medium such as calcium carbonate or calcium oxide, and the fluid medium carrying potassium can be effectively used as an organic component gasification catalyst.
(B) Potassium which has been volatilized in the generated gas and cannot be used in the conventional high-temperature gasification method can be recovered.
[0028]
According to the biomass gasification method of the fourth aspect, the following effect is obtained in addition to the effect of the third aspect.
(A) High-temperature potassium-containing ash discharged from an ash discharge unit provided at the bottom of a fluidized bed in which a fluidized bed is formed can be rapidly cooled to promote vitrification. The alkali content can be stably retained by the glass content in the ash, and a fertilizer excellent in retention of the alkali content such as potassium can be provided.
(B) The gasifier can be used as a device for producing an alkali-containing fertilizer such as a potassium fertilizer, and is excellent in productivity as a system.
(C) Alkaline-containing fertilizers such as potassium fertilizers can be produced at the same time as gasification of biomass particles, so that energy and resources can be effectively used.
[0029]
According to the biomass gasification method of the fifth aspect, the following effect is obtained in addition to the effect of the first aspect.
(A) Since the harmful gas generated at the time of gasification of the biomass particles is captured by the fluid medium, the influence on the surrounding environment due to the release or leakage of the harmful gas is suppressed, and the environmental protection is excellent.
(B) Since the harmful gas is removed when the biomass particles are gasified, the treatment in the subsequent gas treatment step is facilitated, and the overall treatment cost can be reduced and the economy is excellent.
[0030]
According to the biomass gasification method of the sixth aspect, the following effect is obtained in addition to the effect of any one of the first to fifth aspects.
(A) Since the mass ratio between the biomass particles and the fluidized medium in the fluidized bed is set in a specific range, the biomass particles composed of wood pieces and the like can be uniformly and effectively stirred in the fluidized bed.
(B) Since the fluidized state is appropriately maintained, the control of the partial oxidation reaction of hydrocarbons is facilitated, and the amount of low molecular weight hydrocarbons generated by reducing CO generation is improved, and the calorific value of generated gas is improved. Can be.
[0031]
According to the biomass gasification method of the seventh aspect, the following effect is obtained in addition to the effect of any one of the first to sixth aspects.
(A) Since it has a gas circulation adjustment step of processing and circulating a part of the generated gas, the controllability of adjusting the amount of circulating gas according to the fluidized state of the fluidized bed is excellent, and the biomass is always decomposed. The gasification conditions are appropriately maintained, and a large amount of purified gas containing less impurities such as tar and char can be produced, resulting in excellent productivity.
(B) A part of the gas obtained by gasifying biomass from the fluidized bed can be taken out, subjected to dust removal treatment and circulated and supplied to the fluidized bed, and the inside of the fluidized bed composed of biomass particles and the fluidized medium can be adjusted to appropriate conditions. It can be maintained and the operation in a state where the decomposition gasification efficiency is enhanced can be easily performed.
(C) Since heat can be recovered from a part of the generated gas, heat loss is reduced and the economy is excellent.
[0032]
According to the biomass gasifier of the eighth aspect, the following effects are obtained.
(A) Since the biomass gasifier has a fluidized bed formed by an oxidizing gas, a fluidized bed composed of biomass particles and a fluidized medium carrying an organic component gasification catalyst is used. The reaction can be caused, the partial oxidation reaction of hydrocarbons can be suppressed, the methane content in the product gas can be secured, and the decrease in the calorific value of the product gas can be effectively prevented.
(B) Since the fuel gas obtained by biomass gasification is applied to a small generator to generate power, and the circulating gas in the fluidized bed and the exhaust gas from the generator can be heat-recovered as low-pressure steam, a dry heat source can be used. The overall thermal efficiency can be improved by using a cogeneration system such as a factory process steam supply.
(C) The alkali component in the biomass particles is captured in the fluidized medium in the fluidized bed, and a product gas with a small amount of alkali can be supplied, the handling thereof is facilitated, and the productivity and workability are excellent.
(D) Since it has a fluidized bed heating section disposed around the fluidized bed section, it has excellent controllability for controlling the temperature in the fluidized bed in which the gasification reaction is performed and heat utilization efficiency, and always has a predetermined gas component. The product gas adjusted to the range can be efficiently produced.
(E) Since it has a heat recovery unit that recovers heat of the generated gas and a dust removal processing unit that removes solid particles in the generated gas using a filter such as a bag filter or a ceramic filter, the thermal efficiency of the device system can be improved. By removing dust from the exhaust gas, the environmental protection can be enhanced.
(F) By operating a gas circulation adjusting section for circulating gas in the fluidized bed section and a fluidized bed heating section for adjusting the temperature of the fluidized bed section in cooperation with each other, flow conditions such as temperature and flow rate in the fluidized bed can be controlled. By controlling, the generation efficiency and heat efficiency of the generated gas can be increased and the operation can be performed efficiently.
(G) Since high-calorie, low-tar, char and other gases can be produced using biomass particles as fuel, subsequent exhaust gas treatment can be facilitated, and gas purification equipment can be omitted or reduced in size, and a small system can be configured.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a biomass gasifier according to a first embodiment.
FIG. 2 is a schematic diagram showing the role and catalysis of a fluid medium.
FIG. 3 is a schematic configuration diagram of a biomass gasifier according to a second embodiment.
[Explanation of symbols]
10 Gasifier of Embodiment 1
11 Flow reaction tank
11a Fluidized bed
12 Biomass supply pipe
13 Fluidized bed heating unit
14 Ash discharge section
15 Dust removal unit
16 Heat recovery section
17 Gas circulation path
17a blower
18 Fluidized bed heat recovery section
19 Oxidizing gas supply unit
19a Fluidizing gas supply pipe
20 Product gas discharge pipe
21 Body shell
30 Gasifier of Embodiment 2
31 Fluidized bed
32 Lock Hopper
33 External hopper
34 pressure vessel
35 Biomass supply pipe
36 Fluidized bed heating unit
37 Ash discharge section
38 cyclone
39 Dust removal unit
40 Combustor (combustor)
41 Generator
41a Gas turbine
41b compressor
41c generator
42 Combustion gas exhaust pipe
43 Circulating gas branch pipe
44 Combustion gas control pipe
45 Compressed air supply pipe
46 Compressed air branch pipe

Claims (8)

Wood pieces, a biomass particle such as wood powder and a fluid medium supporting an organic component gasification catalyst are fluidized with an oxidizing gas to form a fluidized bed, and the fluidized bed is maintained at a temperature of 400 to 600 ° C. A gasification method for biomass, wherein the biomass particles are gasified. The biomass gasification method according to claim 1, wherein the fluid medium is a granular material containing calcium carbonate and / or calcium oxide, and the organic component gasification catalyst is an alkali such as potassium. The biomass according to claim 1, wherein the biomass particles are heated in a fluidized state in the fluidized bed to volatilize an alkali component such as potassium contained in the biomass particles and supported on the fluid medium. 4. Gasification method. The biomass gasification method according to claim 3, wherein the fluidized medium taken out from the bottom of the fluidized bed is cooled to be an alkali-containing fertilizer such as a potassium fertilizer. A harmful gas containing organic substances such as chlorides such as SOx, NOx and dioxins, and environmental hormones generated in the fluidized bed is brought into contact with the fluidized medium in a fluidized stirring state, and is adsorbed and captured to decompose. 2. The method for gasifying biomass according to 1. The mass ratio (A / B) between the biomass particles (A) and the fluid medium (B) loaded in the fluidized bed is from 1/100 to 1/2. The method for gasifying biomass according to any one of the preceding claims. It is characterized by having a gas circulation adjusting step of taking out a part of the gas obtained by gasifying the biomass particles from the fluidized bed, performing a heat recovery treatment and / or a dust removal treatment, and then circulating the gas through the fluidized bed. The biomass gasification method according to any one of claims 1 to 6. Biomass particles such as wood chips and wood powder are supplied from the body wall through a biomass supply pipe, and hold a fluid medium such as calcium carbonate or calcium oxide on which an organic component gasification catalyst such as potassium is supported, and a bottom portion thereof. A fluidized bed provided with a fluidized bed in which a fluidized bed composed of the biomass particles and the fluidized medium is formed by an oxidizing gas supplied via a fluidized gas supply pipe provided in the fluidized vessel; A fluidized bed heating section disposed so as to surround, an ash discharge section provided at the bottom of the fluidized bed section for discharging the ash after the biomass granule decomposition, and the biomass discharged from an upper portion of the fluidized bed section A heat recovery unit and / or a dust removal processing unit that performs heat recovery and dust removal of the product gas obtained by dissolving the particles, and a gas circulation adjustment that circulates the product gas subjected to the heat recovery and dust removal to the lower part of the fluidized bed unit. With a part Gasifier biomass characterized and.

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