JP2009057497A - Gasification method, gas formation apparatus and gasification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasification method which achieves formation of a tar-removed gas and quick gasification of char, a gas formation apparatus, and a gasification apparatus. <P>SOLUTION: First, a carbon based solid fuel such as coal and biomass is heated at 450°C or higher to thermally decompose the carbon based solid fuel into a gas phase component and char. The gas phase component is composed of a gas comprising hydrogen, carbon monoxide and the like and tar. Next, the gas phase component is brought into contact with activated char at 600-800°C to effect coking to decompose the tar. The tar is decomposed on the surface of the activated char into a gas and coke, and the coke is deposited on the surface of the activated char to form a carbon supporting material. Then, the char and the carbon supporting material are brought into contact with a gas containing water vapor to effect gasification for producing a gas comprising hydrogen and carbon monoxide. By gasification, the surfaces of the char and the carbon supporting material are eroded to form activated char which is then recycled in the coking. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a gasification method, a gas generator, and a gasifier for gasifying carbon-based solid fuel.

  Conventionally, as a future energy utilization technology, carbon-based solid fuels such as coal, biological organic biomass, or organic waste are converted into flammable gases such as hydrogen, carbon monoxide, or lower hydrocarbons. Researches and developments have been made on “gasification” to be converted, and “gas turbine power generation”, “gas engine power generation”, and “fuel cell power generation” technologies using this combustible gas.

  When evaluating the performance of gasification technology, “cold gas efficiency” representing “a ratio of chemical energy of generated combustible gas to chemical energy of solid fuel as a raw material” is used as one of the most important indexes. Water vapor, air, nitrogen + air, oxygen, water vapor + air, water vapor + oxygen, or the like is used as the gasifying agent that reacts with the solid fuel to gasify the solid fuel. In the case of using only water vapor as a gasifying agent, the so-called water vapor gasification reaction using water vapor as an oxidizing agent is an endothermic reaction, and therefore it is necessary to heat the reactor from the outside. When the reactor is heated using a part of the generated combustible gas, the cold gas efficiency is reduced accordingly. When a gasifying agent in which oxygen or air is added to water vapor is used, water vapor gasification that is an endothermic reaction and combustion that is an exothermic reaction occur in the reactor. In this case, the greater the contribution of combustion, the higher the reaction temperature, but the lower the cold gas efficiency, while the larger the contribution of steam gasification, the higher the cold gas efficiency, but the lower the reaction temperature and the reaction rate. descend.

  In actual gasification of a solid fuel, thermal decomposition of the solid fuel first proceeds, whereby volatile components are released into the gas phase and a solid carbonaceous material called char is generated. The emitted volatile components are composed of non-condensable light gas and vapor of a heavy compound group called tar. Tar is a substance that becomes liquid or solid at room temperature, and when the gas contains tar, not only the amount of gas generated decreases, but also various types of substances such as tar contaminates the device that uses the gas. There is a problem that trouble occurs or a processing facility for preventing the trouble is necessary. Therefore, in the gasification of the solid fuel, it is necessary to reform the tar contained in the generated gas into a light gas.

The tar reforming is slow at a low temperature of about 800 ° C. and cannot be completed within a few seconds. For this reason, conventionally, it has been considered that a high temperature of 1100 ° C. or higher is required for reforming tar. In order to realize such a high temperature reaction field, it is necessary to excessively input oxygen or air. As a result, not only the cold gas efficiency but also the calorific value per unit volume of the generated combustible gas is reduced. End up. Although attempts have been made to reform tar at a low temperature of about 800 ° C. using a catalyst, when a cheap natural mineral such as dolomite, olivine, or iron oxide is used as the catalyst, the degree of reforming is not sufficient. In addition, when an expensive highly active catalyst such as a nickel-based synthesis catalyst is used as the catalyst, although the degree of reforming is sufficient, it is poisoned by a trace amount of chlorine, sulfur or alkali metal contained in the combustible gas raw material. Therefore, the deactivation of the catalyst occurs early and night, and the higher the activity of the catalyst, the more the deactivation occurs due to carbon deposition (coking) from the tar. Under such circumstances, development of a tar decomposing material and a catalyst having high activity for decomposing tar and avoiding problems such as deactivation and poisoning is desired. Non-Patent Document 1 discloses a technique for reducing the concentration of tar in gas by attaching tar to porous particles such as zeolite or activated alumina.
T.Namioka and three others, “High Tar Reduction with Porous Particles for Low Temperature Biomass Gasification”: Effects of Porous Particles on Tar and "Effects of Porous Particles on Tar and Gas Yields during Sawdust Pyrolysis", Journal of Chemical Engineering of Japan, 2003, Vol. 36, No. 12, p. 1440-1448

  In the gasification of char generated with volatile components in pyrolysis of solid fuel, especially steam gasification, if high concentrations of tar or hydrocarbon gas are present in the gas phase, the gasification inhibition effect by these gas phase components Gasification is very slow or practically does not proceed. There are two types of inhibitory effects, and one is the adsorption of active hydrogen derived from tar and hydrocarbons onto the char surface. In order for char to gasify, water vapor needs to be adsorbed on the char surface. However, if active hydrogen is adsorbed on the char surface, the adsorption of water vapor is hindered. Another inhibitory effect is that tar and hydrocarbon itself adsorb on the char surface and precipitate as a carbon compound. The reaction in which tar and hydrocarbon precipitate as char on the char surface is called coking, and if the coking rate is greater than the char gasification rate, the char gasification will not proceed substantially.

  As described above, when gasifying solid fuel, tar that is difficult in the conventional method to perform gasification with high cold gas efficiency, that is, low-temperature gasification with high water vapor consumption and low oxygen consumption. Therefore, it is necessary to develop an inexpensive decomposable material that can be disassembled and erased. In addition, regarding the gasification of char generated during the thermal decomposition of solid fuel, it is necessary to develop a method for gasifying char after separating tar and hydrocarbons that inhibit gasification from char.

  The present invention has been made in view of such circumstances, and the object of the present invention is to actively perform coking on the surface of char in order to decompose tar when gasifying a carbon-based solid fuel. It is an object of the present invention to provide a gasification method, a gas generation device, and a gasification device that realize generation of gas from which tar has been removed and rapid gasification of char.

  The gasification method according to the present invention is a method of gasifying an organic substance, wherein the organic substance is thermally decomposed into a gas phase component and a carbonaceous solid by heating the organic substance at 450 ° C. or more, and a specific surface area and a pore volume are obtained. By contacting a gas phase component generated by thermal decomposition with a porous carbonaceous material having a larger amount than the carbonaceous solid, or a mixture of the carbonaceous solid and the porous carbonaceous material. A carbon carrier in which a carbonaceous solid is deposited on the surface of the carbonaceous solid or the porous carbonaceous material is generated, and the porous carbonaceous material or the carbonaceous solid and the porous carbonaceous material The gas after the gas phase component is brought into contact with the mixture is recovered.

  The gasification method according to the present invention is characterized in that a gas containing water vapor is brought into contact with the carbonaceous solid and / or the carbon support at 700 ° C. or higher, and the generated gas containing hydrogen or carbon monoxide is recovered. To do.

  In the gasification method according to the present invention, the porous carbonaceous material is a solid material remaining after the carbonaceous solid and / or the carbon support is brought into contact with a gas containing water vapor at 700 ° C. or higher. Features.

  The gas generating apparatus according to the present invention is a gas generating apparatus that generates gas by pyrolyzing organic matter, and means for thermally decomposing the organic substance at 450 ° C. or higher, and recovers vapor phase components and carbonaceous solids produced by the means. A porous carbonaceous material having a specific surface area and pore volume increased from that of the carbonaceous solid, or the carbonaceous solid and the porous carbonaceous material. And carbon in which a carbonaceous solid is deposited on the surface of the carbonaceous solid or the porous carbonaceous material as a result of the vapor phase component permeating into the aggregate. And a means for recovering the carrier, and a means for recovering the gas after allowing the gas phase component to permeate the accumulation.

  The gasification apparatus according to the present invention is a gasification apparatus for gasifying organic matter, wherein the temperature is 700 ° C. or higher on the accumulation of carbonaceous solids and / or carbon supports produced by the gasification method of the present invention. Means for contacting a gas containing water vapor, means for recovering a gas containing hydrogen or carbon monoxide generated by the means, and a gas containing water vapor at 700 ° C. or higher on the carbonaceous solid and / or the carbon carrier. And a means for recovering the porous carbonaceous material remaining after the contact.

  In the present invention, an organic substance such as coal or biomass is pyrolyzed into a gas phase component and char that is a carbonaceous solid, and a porous carbonaceous material or char that has a specific surface area and pore volume increased more than char. The gas phase component is brought into contact with a mixture of the carbonaceous material and the porous carbonaceous material, and the gas after contact is recovered. Tar contained in the gas phase component decomposes into gas and carbonaceous solid on the surface of char or porous carbonaceous material, and char or porous carbonaceous material is carbon on which carbonaceous solid is deposited on the surface. It becomes a carrier.

  In the present invention, the char and / or the carbon support is brought into contact with a gas containing water vapor to gasify the char and / or the carbon support and combustible containing hydrogen or carbon monoxide generated by the gasification. Recover sex gas.

  In the present invention, the char and / or carbon support is not completely gasified, and the char and / or carbon support is partially gasified to increase the specific surface area and pore volume. A substance is produced, and the produced porous carbonaceous substance is used for the decomposition of tar.

  In the present invention, tar contained in a gas phase component obtained by thermally decomposing an organic substance is decomposed using a porous carbonaceous substance, so that the gas can be effectively removed and used as fuel easily. Can be generated.

  Further, in the present invention, since tar is not generated from the produced char and carbon support, gasification inhibition by tar does not occur, char and carbon support are rapidly gasified, and hydrogen or carbon monoxide is generated. The combustible gas containing it can be produced efficiently.

  In the present invention, the porous carbonaceous material remaining after the gasification of the char and the carbon support increases the specific surface area and pore volume, and has a high activity of decomposing tar. The present invention has an excellent effect, such as being able to be used and efficiently gasifying an organic substance while recycling a porous carbonaceous material.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
FIG. 1 is a conceptual diagram showing an outline of the gasification method of the present invention. In the present invention, first, a carbon-based solid fuel such as coal, biomass, or organic waste is heated at 450 ° C. or higher so that the carbon-based solid fuel is converted into a gas phase component and char that is a carbonaceous solid. Thermally decomposes. The gas phase component is composed of a gas containing hydrogen, carbon monoxide, carbon dioxide, lower hydrocarbon gas, and the like, and a condensable compound that becomes liquid or solid when cooled to room temperature. Here, the condensability means the property of becoming a liquid or a solid at normal temperature and normal pressure. This condensable compound is generally called tar. The tar generated when pyrolyzing solid carbon-based resources contains aromatic compounds. Among these compounds, alkylbenzenes such as benzene, toluene, and xylene with one aromatic ring per molecule are not included in tar because they do not cause troubles such as pipe clogging or gas engine operation troubles. Often not. However, even a compound having one aromatic ring has a high boiling point compound such as phenol and is classified as tar. All compounds having two or more aromatic rings are classified as tar. When the gas phase component is not cooled, tar vapor is contained in a non-condensable gas that does not become liquid at room temperature.

In the present invention, the gas phase component comprising gas and tar is then contacted with an activated char which is a porous carbonaceous material having a specific surface area and pore volume increased from char at 600 ° C. to 800 ° C. By doing so, a coking process is performed in which tar is decomposed into a carbonaceous solid called coke. The activated char is a char made more porous by increasing the specific surface area and pore volume, and the activity for decomposing tar on the surface is improved. In the coking process, tar in the gas phase component is adsorbed on the surface of the activated char such as in the pores, and the tar is decomposed into gas and coke by the decomposition action on the surface of the activated char. Coke remains on the surface of the activated char. This coking process eliminates the need to install a process dedicated to tar processing downstream, eliminates the tar to a low concentration and does not cause trouble in operation of a gas combustor such as a gas engine. Gas that does not contain is produced. The upper limit concentration of tar that a gas engine can tolerate is generally said to be about 100 mg-tar / Nm ³ . In the coking treatment, coke is deposited on the surface of the activated char, so that the activity of the activated char is lost, and a carbon carrier in which coke is deposited on the surface of the activated char is generated. As a substance for depositing coke from tar, a mixture of activated char and char may be used. Although char has a lower ability to decompose tar than activated char, tar can be decomposed in the same manner as activated char to form a carbon support with coke deposited on the surface of char.

  Conventional pyrolysis and coking processes produce char, carbon support, and non-condensable gas that does not contain tar. Among these products, non-condensable gas can be converted into electric power and / or heat by using a gas engine or a gas turbine or the like, and can be converted into a hydrocarbon using a steam reforming catalyst or the like. It can also be converted to synthesis gas that does not contain. Further, the char and the carbon support are high-grade solid fuels that do not generate any tar even when heated, that is, have a tar-free property, and can be used by mixing them without distinction.

  Next, in the present invention, the char and the carbon support are gasified using water vapor, water vapor + air, water vapor + oxygen or the like as an oxidizing agent (gasifying agent), and combustible mainly containing hydrogen and carbon monoxide. A gasification process for generating gas is performed. No tar is generated from the char and the carbon support, and almost no hydrocarbon gas is generated. Therefore, not only equipment for treating tar is not necessary, but in a gasification reactor for gasification, tar and Since gasification inhibition by hydrocarbons does not occur, rapid gasification is possible at low temperatures. In this gasification treatment, it is not necessary to gasify all of the char and the carbon carrier, and in addition to the combustible gas, an activated char having physical properties similar to activated carbon can be produced together. In the char and carbon support, coke or surface material deposited on the surface is gasified by gasification treatment, the specific surface area and pore volume are increased, and porous activated char is generated. The activated char generated here is used in the coking process.

  The ratio of gas and activated char produced in the gasification process can be controlled by the gasification temperature, the composition of the gasifying agent, the feed rate, and the residence time of the char and carbon support in the gasification reactor. The combustible gas generated by gasification can be converted into electric power and / or heat using a gas engine, a gas turbine, a fuel cell, or the like. Since the activated char has a larger specific surface area and pore volume than the char or carbon support before being subjected to gasification, it can be effectively used in the coking process. That is, activated char can be produced from char, and the carbon support can be regenerated into activated char.

  FIG. 2 is a schematic cross-sectional view showing a configuration example of the gas generation device of the present invention. The gas generator includes a cracking reactor 11 that performs thermal decomposition of a carbon-based solid fuel, and a coking reactor 21 that performs coking processing. The cracking reactor 11 is formed in a hollow cylindrical shape, and a hopper 14 for supplying carbon-based solid fuel into the cracking reactor 11 is coupled to one end, and from one end to the other end in the cracking reactor 11. A conveying screw 13 is provided. The conveying screw 13 has a configuration in which a spiral blade is provided around a rotation axis coaxial with the decomposition reactor 11. The conveyance screw 13 conveys the carbon-based solid fuel supplied to one end in the cracking reactor 11 to the other end by rotating about the rotation axis. The cracking reactor 11 is installed through the furnace 12 in a substantially horizontal posture. The furnace 12 has 450 to 600 in the decomposition reactor 11 by heat supply by burning a part of the gas generated in the present invention, electric heating, heating by waste heat of a gas engine or a gas turbine, or a combination thereof. Heat to ° C. At the other end of the cracking reactor 11, there are a pipe 15 for guiding the gas phase component generated from the carbon-based solid fuel by pyrolysis to the coking reactor 21, and a collector 16 for recovering the char generated from the carbon-based solid fuel. Is provided. As the configuration of the decomposition reactor 11, a screw conveyor type configuration is shown, but this is an example, and a rotary kiln type or a moving bed type (updraft type, downdraft type) may be used.

  In the caulking reactor 21, a hopper 23 for supplying activated char is provided on the upper side via a particle feeder 24. The activated char is supplied from the hopper 23 by the operation of the particle feeder 24, and the activated char is accumulated in the coking reactor 21. The coking reactor 21 is disposed in the furnace 22. The furnace 22 has 600 to 800 in the coking reactor 21 by heat supply by burning a part of the gas generated in the present invention, electric heating, heating by waste heat of a gas engine or a gas turbine, or a combination thereof. Heat to ° C. The activated char in the coking reactor 21 is appropriately heated by the furnace 22. A pipe 15 is connected to the lower part of the coking reactor 21. The pipe 15 is configured to keep the gas phase component flowing in the pipe warm, such as being covered with a heat insulating material or provided with a heating means. The gas phase component generated by the thermal decomposition of the carbon-based solid fuel flows from the decomposition reactor 11 through the pipe 15 into the coking reactor 21. The caulking reactor 21 is provided with an annular tube having a large number of gas ejection holes in the lower part of the reactor, and the piping 15 is connected to the annular tube. It has a structure that almost uniformly penetrates the accumulation of chemical char. A carbon carrier is generated by the penetration of the gas phase component into the activated char accumulation. Further, a gas recovery pipe 27 for recovering the generated gas is connected to the coking reactor 21 on the upper side, and a particle discharger 26 is provided on the lower side. A recovery unit 25 that recovers the carbon carrier is provided below the particle discharger 26.

  The decomposition reactor 11 and the coking reactor 21 may be configured to heat the inside by supplying hot air to the heat transfer tubes inserted in the inside. Further, the caulking reactor 21 may have a configuration in which a small amount of air or oxygen is introduced to cause a partial combustion reaction to proceed inside and the inside is heated by reaction heat.

  In the gas generating apparatus having the above configuration, the carbon-based solid fuel is continuously supplied into the cracking reactor 11 by the rotation of the transport screw 13, and the carbon-based solid fuel is heated while being transported through the cracking reactor 11, A reaction in which the carbon-based solid fuel is thermally decomposed into a gas phase component and char is continuously performed. The generated gas phase component is supplied into the coking reactor 21 through the pipe 15. The char is transported to the other end in the decomposition reactor 11 by the transport screw 13 and then recovered to the recovery device 16. By adjusting the rotation speed of the conveying screw 13, the supply rate of the carbon-based solid fuel and the generation rate of the gas phase component and char can be adjusted.

  In the coking reactor 21, the activated char is continuously supplied into the coking reactor 21 by the particle supplier 24, and the carbon support is continuously discharged from the coking reactor 21 by the particle ejector 26. Accordingly, a moving bed of activated char is formed in the caulking reactor 21. The supply rate and discharge rate of the activated char are adjusted so that the height of the moving bed falls within a certain range. At this time, it is necessary to maintain a moving bed height sufficient for the tar concentration in the gas generated by the gas generator to be less than the upper limit defined as the gas specification.

  The gas phase component supplied from the decomposition reactor 11 through the pipe 15 penetrates into the activated char moving bed, whereby tar contained in the gas phase component is decomposed and coke is deposited on the surface of the activated char. A carbon support is produced. The produced carbon support is discharged from the coking reactor 21 by the particle discharger 26 and recovered in the recovery unit 25. The non-condensable gas obtained by decomposing tar contained in the gas phase component is recovered from the coking reactor 21 by the gas recovery pipe 27. The collected gas is removed from the moisture through a dust-removing cyclone or filter (not shown) in a cooling tower (not shown) to become a purified fuel gas that can be used in a gas engine or the like. Note that the char recovered in the recovery unit 16 can be supplied from the hopper 23 together with the activated char into the coking reactor 21. Char decomposes tar in the same manner as activated char and coke deposits on the surface to form a carbon support. In this way, by using the gas generating device shown in FIG. 2, it becomes possible to continuously produce a non-condensable gas, a carbon carrier, and char that do not contain tar.

  FIG. 2 shows a gas generating device configured to separate and recover a gas phase component obtained by pyrolyzing carbon-based solid fuel and char, but the configuration of the gas generating device of the present invention is not limited to this. Instead, a configuration in which the gas phase component and the char are recovered without being separated may be employed. That is, the gas generator may not include the pipe 15 and the recovery device 16, and the decomposition reactor 11 may be directly connected to the coking reactor 21. In the case of this form, the vapor phase component and char are supplied from the cracking reactor 11 to the coking reactor 21, activated char is supplied from the hopper 23, and the coking reactor 21 contains a mixture of the activated char and char. And a coking process is performed.

  FIG. 3 is a schematic cross-sectional view showing a part of a configuration example of the gasifier of the present invention. In the gasification reactor 31, a hopper 32 for supplying a carbon carrier and char is provided on the upper side via a particle supplier 33. By the operation of the particle feeder 33, the carbon carrier and char are supplied from the hopper 32, and the carbon carrier and char are accumulated in the gasification reactor 31. A pipe for supplying an oxidant gas containing water vapor to the gasification reactor 31 is connected to the lower portion of the gasification reactor 31. The oxidant gas is water vapor, water vapor + air or water vapor + oxygen.

  When the oxidant gas is only water vapor, the gasification reactor 31 is heated from the outside. The gasification reactor 31 is heated by a heat supply obtained by burning a part of the gas generated in the present invention, electric heating, heating by waste heat of a gas engine or a gas turbine, or a combination thereof. When the oxidant gas contains air or oxygen, steam gasification, which is an endothermic reaction, and combustion, which is an exothermic reaction, are generated in the reactor in the gasification reactor 31, and the consumption rate of water vapor and oxygen is reduced. The temperature in the gasification reactor 31 is determined by the ratio. The ratio of water vapor to oxygen is set so that the temperature in the gasification reactor 31 falls within the range of 800 to 900 ° C., for example. The gasification reactor 31 has a heat retaining structure in order to minimize heat dissipation from the gasification reactor 31.

  The gasification reactor 31 has a configuration in which the supplied oxidant gas can almost uniformly contact the carbon support and the accumulated char. When the oxidant gas comes into contact with the carbon support and the char aggregate, a steam gasification reaction occurs, and a combustible gas mainly containing hydrogen and carbon monoxide is generated. A cyclone 36 is connected to the upper side of the gasification reactor 31, and a recovery pipe 37 for recovering combustible gas and unreacted water vapor is connected via the cyclone 36. Further, a particle discharger 35 is provided below the gasification reactor 31, and a recovery unit 34 for recovering the activated char is provided below the particle discharger 35.

  In the gasification apparatus having the above configuration, the carbon carrier and char are continuously supplied into the gasification reactor 31 by the particle supplier 33, and the activated char is continuously supplied to the gasification reactor by the particle discharger 35. 31 is discharged from the inside. Therefore, a carbon carrier and a char moving layer are formed in the gasification reactor 31. An oxidant gas containing water vapor is supplied into the gasification reactor 31, and the oxidant gas comes into contact with the carbon carrier and char containing carbon as a main component. And flammable gas mainly containing hydrogen gas and carbon monoxide is generated. The generated gas is recovered by the recovery pipe 37 via the cyclone 36. The cyclone 36 captures and collects char fines and ash contained in the gas and unreacted water vapor. Although not shown, if necessary, a dust removal filter may be installed downstream of the cyclone 36 to capture fine powder that is not collected by the cyclone 36. A dryer (not shown) for condensing water vapor is installed downstream of the recovery pipe 37 to dry the generated gas. The obtained combustible gas can be used as a fuel for a gas engine, a gas turbine, or a fuel cell. In addition, when supplying the produced | generated gas to a fuel cell, although gas cooling and water vapor | steam condensation may not be required, it is necessary to remove the hydrogen sulfide contained in gas on the other hand.

  In addition, the carbon carrier and char that are in contact with the oxidant gas are converted into activated char by carbonization of the surface carbon, and are collected by the collector 34. When gasification is performed completely in the gasification reactor 31, the carbon contained in the carbon support and char is completely gasified, and the carbon support and char become ash. By adjusting the supply rate and discharge rate of the carbon support and the char so that they are discharged without being completely gasified, the surface of the carbon support and char is partially gasified. Is eroded, producing a porous carbonaceous material, i.e., activated char, with significantly increased specific surface area and pore volume. The generated activated char can be used in the gas generator shown in FIG.

  Next, an experiment conducted to confirm the ability of activated char as a tar decomposition material will be described. FIG. 4 is a schematic view showing a part of the experimental apparatus used in the experiment. A double-structured reaction tube 41 concentrically provided with two types of reaction tubes having different diameters is provided. A wire mesh 42 is provided downstream of the inner tube, and gas passes through the inner tube and between the inner tube and the outer tube. It was set to flow. As an example of the carbon-based solid fuel, a pine powder sample is used, and pine powder particles and nitrogen gas flow into the inner pipe from the upstream, and the pine powder particles that flow in are collected on the wire mesh 42. It is comprised so that it may do. In addition, water vapor flows as an oxidant gas between the inner tube and the outer tube. Further, a dispersion plate 43 was provided downstream of the wire mesh 42 in the reaction tube 41, and a packed bed of activated char was provided on the dispersion plate 43. A portion where pine sawdust particles are accumulated on the wire mesh 42 is defined as a thermal decomposition zone, and a portion of the packed bed of activated char is defined as a tar decomposition zone. The pyrolysis zone was heated to 500 ° C and the tar decomposition zone was heated to 800 ° C.

  In the experiment, pine powder having a particle diameter of 0.7 to 1.2 mm was constantly supplied at a rate of 0.07 g / min. In the pyrolysis zone, the pine powder is pyrolyzed to produce gas phase components and char. The char remains on the wire mesh 42 and the vapor phase component is continuously introduced into the tar decomposition zone through the wire mesh 42 along with nitrogen gas. In the tar decomposition zone, 0.9 g of activated char having a particle size of 0.15 to 0.25 mm was filled. The gas phase component and nitrogen gas flowing from the thermal decomposition zone are mixed with water vapor and then introduced into the tar decomposition zone. The water vapor concentration in the mixed gas in which the gas phase component, nitrogen gas and water vapor were mixed was 16 vol%. Further, the time for the gas to stay in the packed bed of the activated char was 30 milliseconds. The tar in the gas phase component decomposes into gas and coke while passing through the packed bed of activated char. In the experiment, the entire amount of gas that passed through the tar decomposition zone was recovered, identified and quantified. The amount of coke deposited was determined from the difference in carbon content of the activated char before and after the experiment.

FIG. 5 is an explanatory diagram for explaining the experimental results. The numbers in the figure indicate the relative amount of product on a carbon basis. That is, 9.5 gas and 65 tar were produced from 100 pine powders by pyrolysis, and this gas and tar were supplied to a packed bed of 50 activated char. Tar in this experiment is all aromatic compounds except benzene, toluene and xylene. While 60.5 non-condensable gas was discharged from the tar decomposition zone, no tar was detected from the gas passing through the tar decomposition zone. The lower limit of detection at this time is 0.001 carbon, and the amount of tar is clearly less than 0.001. The 65 tar generated by pyrolysis was decomposed into 51 gas and 14 coke, and the coke was deposited on the surface of the activated char. Due to the deposition of coke, the activated char becomes a carbon support, the specific surface area decreases from 2,310 m ² / g to 1,260 m ² / g, and the pore volume decreases from 0.75 ml / g to 0.43 ml / g. Diminished. Thus, it became clear that the activated char can completely decompose tar even when the contact time is as short as 30 milliseconds.

  As a comparative experiment, an experiment using silica sand particles instead of the activated char was conducted. Silica sand particles are considered to have low tar decomposition activity. In the case of this experiment, tar flowed out downstream of the tar decomposition zone, and the amount of tar that flowed out of 100 pine sawdust was 2.4. The advantage of activated char as a tar decomposition material is obvious.

  6 and 7 are explanatory views for explaining an example of the yield of a product when gasifying a carbon-based solid fuel using the gasification method of the present invention. FIG. 6 shows a case where woody biomass (Japanese cedar chip; 5 mm square × 2 mm thickness) is used as a raw material, and FIG. 7 shows a case where coal (Australian brown coal; particle diameter 3-4 mm) is used as a raw material. . The yields of gas, tar and char produced by pyrolysis were based on the results of pyrolysis experiments conducted using a laboratory scale screw conveyor type continuous pyrolysis reactor, and other values were assumed based on the experimental results. Is. As shown in FIG. 6, when woody biomass is pyrolyzed at 550 ° C., 20 gases, 45 tars and 35 chars are produced. The 45 tar is broken down into 15 coke and 30 gas by coking. At this time, it is assumed that 50 activated chars and chars are used as the tar decomposition material, and 50 of the total 100 carbon carriers and chars are gasified and 50 is the activated char. If 50 activated chars and 35 chars are sufficient to decompose the tar, it is possible to produce tar-free gas while recycling the activated char.

  Further, as shown in FIG. 7, when coal is used as a raw material, the amount of tar generated is reduced, and when coal is pyrolyzed at 600 ° C., 15 gases, 20 tars and 65 chars are generated. . The 20 tar is broken down into 10 coke and 10 gas by coking. In the caulking, 45 activated chars are used. Of the 120 carbon carriers and chars in total, 75 is gasified and 45 is activated char. Since the amount of tar produced from coal is small and the amount of char produced is large, the amount of activated char recycled can be reduced. As described above, no matter what carbon-based solid fuel is used as a raw material, if the necessary amount of activated char recycle is clarified, the gas generated by coking and gasification from 100 raw materials It is possible to produce a tar-free gas with a yield of 100 in combination with the gas to be purified in step (b).

It is a conceptual diagram which shows the outline | summary of the gasification method of this invention. It is typical sectional drawing which shows the structural example of the gas production | generation apparatus of this invention. It is typical sectional drawing which shows a part of structural example of the gasifier of this invention. It is the schematic which shows a part of experiment apparatus used for experiment. It is explanatory drawing explaining an experimental result. It is explanatory drawing explaining the yield example of the product at the time of gasifying a carbonaceous solid fuel using the gasification method of this invention. It is explanatory drawing explaining the yield example of the product at the time of gasifying a carbonaceous solid fuel using the gasification method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Decomposition reactor 15 Piping 16 Recovery | recovery device 21 Coking reactor 25 Recovery | recovery 27 Gas recovery pipe 31 Gasification reactor 34 Recovery | recovery 37 Recovery pipe

Claims (5)

In the method of gasifying organic matter,
By heating the organic matter at 450 ° C. or higher, the organic matter is thermally decomposed into a gas phase component and a carbonaceous solid,
A gas phase component generated by pyrolysis is added to a porous carbonaceous material having a specific surface area and pore volume increased from that of the carbonaceous solid, or a mixture of the carbonaceous solid and the porous carbonaceous material. By contacting, a carbon carrier in which a carbonaceous solid is deposited on the surface of the carbonaceous solid or the porous carbonaceous material is generated,
A gasification method comprising: recovering a gas after contacting the gas phase component with the porous carbonaceous material or a mixture of the carbonaceous solid and the porous carbonaceous material. Contacting the carbonaceous solid and / or the carbon support with a gas containing water vapor at 700 ° C. or higher,
The gasification method according to claim 1, wherein the gas containing hydrogen or carbon monoxide that is generated is recovered. The porous carbonaceous material is a solid material remaining after the carbonaceous solid and / or the carbon support is brought into contact with a gas containing water vapor at 700 ° C. or higher. Gasification method. In a gas generator that generates gas by thermal decomposition of organic matter,
Means for pyrolyzing organic matter at 450 ° C. or higher;
Means for recovering the gas phase component and the carbonaceous solid produced by the means;
The gas phase component recovered by the means is a porous carbonaceous material having a specific surface area and pore volume increased from that of the carbonaceous solid, or a mixture of the carbonaceous solid and the porous carbonaceous material. Means for infiltrating the accumulated material,
Means for recovering a carbon carrier in which a carbonaceous solid is deposited on the surface of the carbonaceous solid or the porous carbonaceous material as a result of the vapor phase component penetrating into the aggregate;
And a means for recovering the gas after allowing the gas phase component to permeate the accumulation. In a gasifier that gasifies organic matter,
Means for bringing a gas containing water vapor having a temperature of 700 ° C. or higher into contact with an accumulation of carbonaceous solids and / or carbon supports produced by the gasification method according to claim 1;
Means for recovering a gas containing hydrogen or carbon monoxide generated by the means;
Means for recovering the porous carbonaceous material remaining after contacting the carbonaceous solid and / or the carbon carrier with a gas containing water vapor at 700 ° C. or higher.

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