JP2006291134A - Gasification method for biomass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method which causes the gasification reaction of a biomass to efficiently and effectively proceed under relatively low temperature conditions, thus solving the problem accompanying the occurrence of tar or soot, reducing the thermal load of an apparatus material, decreasing heat loss, preventing the melting of vegetal ashes or a gasification accelerator, and realizing a more stable control. <P>SOLUTION: The gasification method of a biomass uses an apparatus equipped with a gasification reaction zone 1 and a regeneration zone 2 and includes a step of circulating, between both the zones, a gasification accelerator having a catalytic function and/or a heat medium function. The gasification reaction zone and the regeneration zone are adjoined to each other through a thermally conductive partition wall 3; thus heat transfer by radiation, conduction, and convection from the regeneration zone to the gasification zone is enabled, the temperature of the regeneration zone is lowered, and the automatic temperature adjustment function of the apparatus for gasification is enhanced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to biomass fueling technology, and more particularly to an efficient method for gasifying biomass to produce gaseous fuel or liquid fuel such as methanol.

  Today, in order to prevent global warming and avoid the depletion of finite fossil fuel resources, it is an urgent task to develop and widely disseminate natural energy technology. Among renewable energies, biomass energy is often positioned as the top of renewable energies because it has a large potential and can be converted to fuel.

  Biomass energy utilization technologies include direct combustion, thermochemical conversion technology, and biochemical conversion technology, but direct combustion has limited efficiency, especially for small-scale processes. Only limited biomass such as starch can be used as raw material. On the other hand, according to thermochemical conversion, biomass including cellulosic compounds can be used as a whole, and high-efficiency energy can be used even on a small scale.

As a thermochemical conversion technique that has been developed so far, for example, there is a method described in JP-A-7-138580 (Patent Document 1). This is a method of partially oxidizing an organic substance with air or oxygen and water vapor, adjusting the molar ratio of the water vapor to be supplied to the carbon in the organic substance to be 1 to 10, and further having a combustion or gasification temperature of 700. It adjusts so that it may be set to ° C-900 ° C. Japanese Patent Laid-Open No. 9-111254 (Patent Document 2) is provided with a nickel-containing alloy or nickel catalyst provided on the downstream side of the gasification furnace containing tar and soot in the gas generated by such a method. There has been proposed a method of decomposing by a gas decomposition furnace. Furthermore, in JP 2002-212574 (Patent Document 3), a fluidized bed furnace is provided around a furnace for gasifying biomass with steam, the biomass is burned in the fluidized bed furnace, and heat is supplied to the gasification furnace. How to do is described. Japanese Patent Application Laid-Open No. 2003-246990 (Patent Document 4) discloses a fluidized bed using a catalyst represented by Rh / CeO ₂ / M (where M is SiO ₂ , AlO ₂ , Al ₂ O _3, or ZnO ₂ ). In the reactor, a method for gasifying biomass at less than 800 ° C. has been proposed.

  According to the knowledge of the present inventor, the conventional methods described above have the following problems to be solved.

(1) Method of partially oxidizing biomass with air or oxygen and water vapor In this method, tar is produced as a by-product at a reaction temperature of 700 ° C. or lower, which is a heat recovery device, a gas scrubber, In addition, even the shift reaction apparatus, the CO ₂ removal apparatus, and the methanol synthesis apparatus are clogged and the reaction yield is reduced. In order to avoid this, if it is attempted to maintain the temperature of the gasifier at 700 ° C. or higher, it is necessary to burn more biomass, which lowers the yield of the target gas and increases the structure of the gasifier. It is necessary to make the material highly heat resistant. Furthermore, air or oxygen must be introduced into the gasifier for the above combustion, but if air is used, the product gas will be diluted with nitrogen, and if oxygen is used, pure oxygen will be purified from the air. This is a disadvantage in terms of manufacturing cost.

(2) Method of installing a cracking furnace downstream of the gasification furnace in the above process It is considered that the polymerization and condensation reaction of the decomposition products proceed in the process from the gasification furnace to the gas cracking furnace. This is disadvantageous in terms of thermal efficiency because new heating must be performed at the stage of introducing the gas to the gas decomposition furnace. In addition, the catalyst used in the gas cracking furnace is severely degraded and requires frequent replacement.

(3) Method of installing a fluidized bed furnace for burning biomass around the gasification furnace Since this is a non-catalytic reaction, the temperature of the gasification furnace is 700 ° C or higher, more preferably 800 ° C, in order to prevent tar formation. Since the fluidized bed furnaces require higher temperatures, the structural materials of those furnaces need to be expensive heat-resistant materials. Moreover, the heating of the biomass in the gasification furnace mainly depends on radiation from the furnace wall, and the heat transfer efficiency is limited. Therefore, the thermal efficiency of the device is lowered.

(4) Method of gasifying biomass in a fluidized bed reactor using a catalyst The catalyst used in this method is expensive and cannot be deteriorated.

  That is, in general, non-catalytic gasification needs to be performed at a high temperature because tar is generated at a low temperature, and an increase in the thermal burden on the apparatus material and a decrease in thermal efficiency cannot be avoided. In the method of partial combustion using air as part or all of the gasifying agent, the generated gas becomes a gas with a low calorific value and low quality. In order to avoid this, the external heating type gasification furnace with only the gasifying agent as steam has low thermal efficiency. If a catalyst is used, the gasification temperature can be lowered, but the catalyst is generally expensive and promptly. There was a problem of deterioration.

  In order to solve these problems, the present inventors previously made an organic material containing biomass into a catalytic function and / or a heat medium in a gasification reaction zone under a temperature rising condition and in the presence of a gasifying agent. A technique for converting the organic material into a useful gas for producing a gas / liquid fuel by fluid contact with a gasification accelerator made of clay having a function has been proposed (Japanese Patent Laid-Open No. 2003-41268 ( Patent Document 5)). According to this technique, an organic material can be efficiently gasified under a relatively mild temperature condition of 400 to 750 ° C. without generating tar.

The gasification method in this prior invention is a method in which a reaction tank constituting a gasification zone is operated in a relatively high temperature range to avoid carbon deposition on the gasification accelerator, and a reaction is performed in a relatively low temperature range. Depositing a carbonaceous component on the gasification accelerator and removing the carbon content by combustion in a regeneration zone provided separately from the reaction zone, or by partial combustion and a carbonaceous gasification reaction. is there. Of these two methods, the latter is a more preferable method because it can be gasified at a lower temperature and the quality of the product gas is excellent. However, in this latter method, when the gasification zone and the regeneration zone are separated and the heat transfer between them is performed exclusively by the gasification accelerator, the regeneration zone is heated to a high temperature even if the gasification zone can be cooled. For this reason, there is a concern that a thermal burden is applied to the device material, heat loss from the device is relatively large, and the plant ash and the gasification accelerator are melted. Further, the temperature of the gasifier is likely to fluctuate, and adjustment thereof is not easy.
JP-A-7-138580 JP-A-9-111254 JP 2002-212574 A JP 2003-246990 A JP 2003-41268 A

  The present invention was made in order to further improve and improve the above-described prior invention, and the biomass gasification reaction is efficiently and effectively performed under relatively low temperature conditions as a whole apparatus including the regeneration zone. This eliminates the problems associated with tar and soot generation, reduces the thermal burden on equipment materials, reduces heat loss, prevents melting of plant ash and gasification accelerators, and is more stable. It is an object of the present invention to provide a method for realizing such control.

  In order to solve the above problems, a biomass gasification method according to the present invention includes a gasification reaction zone and a regeneration zone, and a gasification accelerator having a catalytic function and / or a heat medium function is circulated between the two. , Put an organic substance containing biomass into the gasification reaction zone and gasify it in the presence of a gasifying agent and a gasification accelerator, and the gasification accelerator with adsorption by-products such as carbon deposited on the surface is put into the regeneration zone. And by adsorbing by-products adhering to the gasification accelerator in the regeneration zone by combustion or by partial combustion and carbonaceous gasification reaction, the heated gasification accelerator regenerated in this way is A biomass gasification method including a step of recirculating to a gasification reaction zone, wherein the gasification reaction zone and the regeneration zone are adjacent to each other through a partition wall having thermal conductivity, and the regeneration zone Heat transfer from the gas to the gasification reaction zone by radiation, conduction and convection through the partition, thereby reducing the temperature of the regeneration zone compared to the case without such heat transfer. The automatic temperature adjustment function of the apparatus for gasification is enhanced.

  In a preferred embodiment of the biomass gasification method according to the present invention, the temperature conditions in the gasification reaction zone and the regeneration zone are 400 ° C. to 800 ° C., preferably 400 ° C. to 750 ° C., more preferably in the gasification reaction zone. Comparison between 450 ° C. and 600 ° C., and in the regeneration zone a temperature range of 25 ° C. to 300 ° C. higher than the gasification reaction zone, preferably a temperature higher by 25 ° C. to 200 ° C., more preferably a temperature range higher by 25 ° C. to 150 ° C. It consists of mild conditions.

  Further, in the present invention, preferably, the gasification accelerator in the gasification is at least one selected from the group consisting of smectite clay, vermiculite clay, kaolin-serpentine clay, chlorite clay, and mixtures thereof. Comprising.

  In still another preferred embodiment of the present invention, the gasifying agent in the gasification contains water vapor.

  Further, in a preferred embodiment of the present invention, the length of the wall separating the gasification reaction zone and the regeneration zone is 20% or more, preferably relative to the circumferential length of the horizontal section of the fluidized bed portion of the gasification reaction zone. Occupies 30% or more, more preferably 40% or more.

  According to the present invention, compared with the case where the gasification zone and the regeneration zone are separated and the heat transfer between them is only heat transfer using the gasification accelerator as a heat medium, as proposed in the past. In addition to such heat transfer, heat transfer by radiation, convection, and conduction through the partition walls of both zones occurs, and in particular, the heat transfer rate in the portion where both surfaces of the wall are fluidized beds is remarkably increased. For this reason, the amount of heat transfer which a gasification promoter should bear can be made relatively small. That is, the temperature of the regeneration zone can be effectively reduced without adversely affecting the entire gasification process under a constant gasification promoter circulation rate. This reduces the thermal load on the device material and reduces the heat loss from the device, thereby improving the thermal efficiency of the device. In addition, ash contained in biomass such as plant ash and gasification accelerators melt at high temperatures and hinder smooth flow, but the risk can be reduced or eliminated.

  Furthermore, this gasification reaction has a low yield of gas at low temperatures, while the yield of by-products such as carbon components deposited on the gasification accelerator increases, and the yield of gas increases as the temperature increases. Thus, the yield of the by-product is lowered. At a certain gasifier temperature, there is a balance between the gas / byproduct yield distribution and the supply of heat to the gasifier by the byproduct combustion heat in the regeneration zone. If the temperature of the gasifier is too high compared to the appropriate temperature and the yield of by-products is low, less heat is generated by the combustion of by-products in the regeneration zone, and the temperature in the regeneration zone is lowered, resulting in gasification. The heat transferred to the zone is reduced, and the temperature of the gasifier decreases. On the other hand, if the temperature of the gasifier is too low compared to the appropriate temperature, the yield of by-products will increase, the combustion heat of by-products in the regeneration zone will increase and the temperature of the regeneration zone will rise, and the gasification zone will increase. The heat transfer rate to the gas increases and the temperature of the gasification zone increases. By this feedback mechanism, the temperature of the gasifier tends to be automatically adjusted to an appropriate optimum point.

  In an apparatus in which the gasification zone and the regeneration zone are separated, the heat transfer from the regeneration zone to the gasification zone for demonstrating this automatic adjustment mechanism is performed exclusively by the circulation of the gasification accelerator. In other words, fluctuations in the temperature conditions are large and troubles are likely to occur. In this regard, in the present invention, since the gasification zone and the regeneration zone are both in a fluidized bed state and are adjacent to each other across a wall having a high heat transfer rate, heat transfer from the regeneration zone to the gasification zone is rapid. The feedback is performed without delay. That is, the automatic temperature control function of the apparatus for gasification can be enhanced. For this reason, it is possible to perform a stable operation with little variation in temperature conditions.

  According to the method of the present invention, an organic material raw material having a gasification reaction zone and a regeneration zone and containing biomass is subjected to a catalytic function and / or in a gasification reaction zone under a temperature rising condition and in the presence of a gasifying agent. A gasification accelerator in which the organic material is converted to a useful gas for producing a gaseous fuel or a liquid fuel by fluid contact with a gasification accelerator having a heat medium function, and by-products such as carbon are adsorbed. Is extracted from the gasification reaction zone and introduced into the regeneration zone, and the adsorption by-products adhering to the gasification accelerator in the regeneration zone are removed by combustion or by partial combustion and carbonaceous gasification reaction. In the gasification method including the step of recirculating the regenerated heated gasification accelerator to the gasification reaction zone, the thermal load applied to the apparatus material by reducing the temperature of the regeneration tower This reduces the heat loss from the equipment, reduces or eliminates the risk of melting plant ash and gasification accelerators, and further increases the automatic temperature adjustment function of the equipment to make it more stable. Driving can be realized.

  The biomass gasification method according to the present invention includes a gasification reaction zone and a regeneration zone, circulates a gasification promoter having a catalytic function and / or a heat medium function between the two, and includes the biomass in the gasification reaction zone. An organic substance is introduced and gasified in the presence of a gasifying agent and a gasification accelerator, and a gasification accelerator with adsorption by-products such as carbon deposited on the surface is led to the regeneration zone, and gasification is performed in the regeneration zone. A step of removing adsorption by-products adhering to the promoter by combustion or by partial combustion and carbonaceous gasification reaction, and recirculating the heated gasification promoter thus regenerated to the gasification reaction zone The gasification reaction zone and the regeneration zone are adjacent to each other through a partition wall having thermal conductivity, and the release from the regeneration zone to the gasification reaction zone is performed. The heat transfer by radiation, conduction and convection is carried out through the partition, thereby reducing the temperature of the regeneration zone compared to the case without such heat transfer and the device for gasification. The automatic temperature control function is enhanced.

  Hereinafter, the present invention will be described more specifically with reference to the accompanying drawings. FIG. 1 is a sectional view showing a basic configuration of an apparatus for carrying out a biomass gasification method according to the present invention. As schematically shown in FIG. 1, in the apparatus for carrying out the method of the present invention, a gasification reaction zone 1 and a regeneration zone 2 are provided adjacent to each other via a partition wall 3 having thermal conductivity. ing. Gasification reaction zone 1 is charged with an organic substance containing biomass and gasified in the presence of a gasifying agent and a gasification accelerator, and a gasification accelerator with adsorption by-products such as carbon deposited on the surface is placed below the partition wall. The adsorbed by-product adhering to the gasification accelerator in the regeneration zone 2 is removed by combustion or by partial combustion and carbonaceous gasification reaction. The heated gasification accelerator regenerated in this manner is further recycled to the gasification reaction zone 1, for example, through the same hole. In order to maintain the heat balance of the apparatus, auxiliary fuel such as biomass may be introduced into the regeneration zone 2 as well. Reference numeral 4 denotes a cyclone.

  In the present invention, in the operating state of both zones, heat transfer by radiation, conduction and convection from the regeneration zone 2 to the gasification reaction zone 1 is effectively performed via the partition walls 3.

  The shapes of the gasification reaction zone 1 and the regeneration zone 2 to which the present invention can be applied are not particularly limited, and the horizontal cross section of each zone may be a circle, an ellipse, a quadrangle, or a shape corresponding thereto. However, the two zones must be adjacent to each other with the partition wall 3 therebetween.

  The width of the partition wall 3 separating the gasification reaction zone 1 and the regeneration zone 2 is such that the horizontal direction in the fluidized bed portion of the gasification reaction zone 1 is sufficient to ensure sufficient heat transfer from the regeneration zone 2 to the gasification reaction zone 1. It is desirable that it is 20% or more, preferably 30% or more, more preferably 40% or more of the circumference of the cross section.

  The material of the partition wall 3 is not particularly limited as long as it is excellent in thermal conductivity and can withstand the operating temperature. For example, 18Cr-8Ni stainless steel, nickel-base heat-resistant alloy, etc. can be preferably used.

  As a preferable temperature condition of the gasification reaction zone 1, it is the range of 400 degreeC-800 degreeC, Preferably it is 400 degreeC-750 degreeC, More preferably, it is 450 degreeC-600 degreeC. On the other hand, as a preferable temperature condition of the regeneration zone 2, the temperature is 25 ° C to 300 ° C higher than the temperature of the gasification reaction zone, preferably 25 ° C to 200 ° C higher, more preferably 25 ° C to 150 ° C higher. It is desirable to use relatively mild conditions.

  The biomass raw material to which the method of the present invention can be applied is not particularly limited, and includes all organic useful materials from which a useful gas for synthesizing liquid fuel such as gaseous fuel or methanol can be obtained. Specifically, woody materials derived from forests or forests, wetlands, rivers, grasslands, plant and algae resources from the ocean, forestry and agricultural waste, waste plastics, etc. are included.

  The pulverization or refinement of the organic material containing biomass is important for increasing the contact area (specific surface area) during the gasification reaction and performing the reaction effectively and efficiently. In this case, the degree of pulverization of the raw material is 300 to 3000 μm, preferably about 300 to 600 μm.

  In the present invention, such an organic material is converted into a gasification accelerator comprising a clay having a catalytic function and / or a heat medium function in a gasification reaction zone in the presence of a gasifying agent under temperature rising conditions. Make fluid contact.

  As a gasifying agent necessary for gasification, a mixture of heated steam and air can be used, but it is more preferable to use only steam in order to prevent a decrease in the concentration of the product gas. Steam is particularly desirable because it has a fluidizing function of the catalyst and a function of stripping oil on the catalyst. Further, as will be described later, by introducing air in the regeneration zone, adsorption by-products on the clay catalyst can be removed by combustion or by partial combustion and carbonaceous gasification reaction.

  It should be noted that the optimum amount of the gasification agent introduced into the gasification reaction zone and the temperature condition can be appropriately selected according to the type, amount and properties of the biomass raw material to be reacted. Usually, the input amount of water vapor as a gasifying agent is in the range of 0.3 to 2.5, preferably 0.5 to 1.0 in terms of steam / biomass ratio. Details of the temperature conditions for the gasification reaction will be described later.

  Further, the introduction of water vapor is preferably performed in such a manner that powder flows, and by such fluidization, water vapor in the gasification reaction zone, biomass polymer or thermal decomposition product released into the gas phase, and catalyst particles Fluidized contact gasification can be performed with good contact between the two.

  The gasification accelerator to be fluidly contacted in the gasification reaction is made of clay having a catalytic function and / or a heat medium function, but is optimal in consideration of the type of biomass, the design of downstream equipment, and the cost of the entire process. Can be selected. Specifically, the gasification accelerator is preferably a smectite clay such as montmorillonite, beidellite, nontronite, kaolinite, kaolinite, halloysite, kaolin-serpentine clay such as cronstedite, chlorite clay, and the like. It comprises at least one selected from the group consisting of these mixtures.

  As the gasification accelerator, in addition to clay as an essential component, it was selected from other minerals, diatomaceous earth, shells, silica-alumina-based catalysts, transition metal-supported inorganic material-based catalysts, metal oxide catalysts, and mixtures thereof. At least one kind can be additionally added as necessary.

  In addition, the particle size of the gasification accelerator is preferably about 10 to 500 μm, and more preferably 60 to 300 μm.

  The optimum amount of the gasification accelerator can be selected in accordance with the type and properties of the gasification accelerator and biomass material used and the equipment used.

  Conventionally, in the method of generating gas fuel or useful gas for methanol synthesis from biomass raw materials, the deterioration of the catalyst is faster than expected in the research using the catalyst in the gasification furnace, and it is not put into practical use at present It is. As described above, the biggest problem in generating useful gas from biomass raw material is the generation of tar. When the gasification reactor is operated at a relatively low temperature condition of 700 ° C. or lower, tar generation cannot be avoided, and conversely, at a high temperature condition of 900 ° C. or higher, tar generation is prevented, but the process self-sustaining heat Maintaining balance becomes difficult. The present inventor has found that the above-mentioned difficult problems can be solved at once by bringing the biomass raw material into contact with a gasification accelerator made of clay as described above in a fluidized state.

  In general, the tar content is generated by the polymer released from the solid phase biomass remaining in the gas phase without being decomposed or by condensation or polymerization of a thermal decomposition product having an unsaturated bond. Such a free component is considered to be promptly decomposed or its polymerization is suppressed, for example, by the presence of a metal catalyst having affinity with a hydrogen atom or a proton-donating acid catalyst. As described above, in the present invention, the gasification reaction is advanced by bringing the fine powdery gasification accelerator and the fine powdery biomass into contact with each other in the fluidized state, thereby generating tar in the gas phase. It can be effectively prevented and the required temperature of the reaction zone can be significantly reduced. Therefore, according to this method, the yield of the product gas and the heat balance of the process can be dramatically improved. Furthermore, introduction of the gasification accelerator as described above into the reaction system is important in order for the gasification accelerator to act as a heat medium and to efficiently advance the gasification reaction.

  Therefore, in the present invention, an extremely easily available and inexpensive clay component such as smectite clay (pretreated if necessary) is used as a gasification accelerator, and this is continuously regenerated in the regeneration zone. A gasification reaction can be performed. According to this method, a part of the gasification accelerator is continuously replaced at a relatively high exchange rate, and the carbon component deposited on the gasification accelerator by the decomposition reaction is removed in the regeneration zone, The catalytic cracking reaction can be carried out efficiently while maintaining the catalytic activity of the oxidization accelerator.

  In the present invention, biomass is gasified while circulating the gasification accelerator having the catalytic function / heat medium function as described above between the gasification reaction zone (gasification furnace) and the regeneration zone (regeneration tower). At this time, the circulation amount of the gasification accelerator is determined so that the catalyst / biomass ratio is appropriate. On the other hand, since this gasification accelerator also has a heat medium function, the amount of circulation must be set so that the heat balance between the gasification reaction zone and the regeneration zone is balanced. The appropriate temperature of the regeneration zone can be determined so that these two requirements are met. That is, the temperature condition of the regeneration zone is determined so that the heat balance of the apparatus is balanced in the circulation amount determined from the appropriate value of the catalyst / biomass ratio.

  As conventionally proposed, in the case of using an apparatus in which the gasification reaction zone and the regeneration zone are separated, the heat transfer of both is performed exclusively using the gasification accelerator as a medium. When the two are adjacent to each other through a wall having a large heat transfer rate, heat transfer through the partition walls is performed in addition to the gasification accelerator, so that the amount of heat transferred by the gasification accelerator is significantly reduced. Thereby, the temperature of the regeneration zone (regeneration tower) can be set lower at a constant circulation speed determined from the requirement of the catalyst / biomass ratio. As a result, the thermal load applied to the device material is reduced, and a cheaper material can be used. Or when the same raw material is used, the durability can be improved. Furthermore, lowering the temperature of the regeneration tower leads to reduction of heat loss from the apparatus.

  In addition, the ash contained in biomass such as plant ash melts when exposed to high temperatures, and the melt may condense and solidify in the low-temperature part or prevent a smooth flow state. Gasification accelerators also melt at high temperatures. Although the activity may be lost, the danger can be avoided by reducing the temperature of the regeneration tower.

  Furthermore, in the method of gasifying biomass by bringing it into contact with a catalyst in the presence of steam in a temperature-raising condition, generally the higher the gasification temperature, the higher the gas yield, while the collection of by-products such as carbon. The lower the rate and the lower the gasification temperature, the smaller the yield of gas and the greater the yield of by-products. At a certain gasifier temperature, there is a balance between the gas / byproduct yield distribution and the supply of heat to the gasifier by the combustion heat of the byproduct in the regeneration tower. When the temperature of the gasifier is too high compared to the appropriate temperature and the yield of by-products is low, the heat generated by the combustion of by-products in the regeneration tower is low, the temperature in the regeneration tower decreases, and the gas The heat transferred to the gasifier decreases, and the temperature of the gasifier decreases. On the other hand, if the temperature of the gasifier is too low compared to the appropriate temperature, the yield of by-products will increase, the combustion heat of by-products in the regeneration tower will increase, the temperature in the regeneration tower will rise, and gasification will occur. The heat transfer rate to the furnace increases and the temperature in the gasifier increases. By this feedback mechanism, the temperature of the gasifier tends to be automatically adjusted to an appropriate point. However, in an apparatus in which the gasification furnace and the regeneration tower are separated, heat transfer from the regeneration tower to the gasification furnace for demonstrating this automatic adjustment mechanism is performed exclusively by the circulation of the gasification accelerator. If the gasification temperature is too high, the carbon yield is low, and the temperature of the regeneration tower is lowered, the temperature of the gasification reactor will be lowered accordingly. Even if it reaches the temperature, the temperature continues to fall further due to the delay in the feedback. Conversely, if the gasification temperature is too low, the regeneration tower temperature rises due to the large amount of carbon produced, and the gasification furnace temperature also rises, but even after the gasification furnace temperature has become appropriate. Since the feedback takes time, the temperature of the gasifier continues to rise further. As such, the gasification method has a mechanism in which the temperature is automatically adjusted to the optimum point, but the temperature tends to fluctuate between the optimum points. However, when the gasification furnace and the regeneration tower are adjacent to each other through a partition wall having excellent thermal conductivity as in the present invention, the temperature change in the regeneration tower due to the change in combustion heat in the regeneration tower is a gasification accelerator. Without waiting for the circulation of the gas, it is quickly transmitted to the gasification furnace through the partition wall, so that the delay of the feedback is eliminated, the automatic temperature control mechanism of the apparatus is enhanced, and the stable operation with less fluctuation of the temperature condition can be performed. It becomes possible.

  Here, in the conventionally proposed technique, when oxygen is supplied for performing the partial oxidation, separation and purification of oxygen from air is required. On the other hand, when air is supplied, a gas for methanol synthesis is used. There is a problem of being diluted with nitrogen. However, according to the method of the present invention, since air is used for combustion, it is not necessary to separate oxygen, the air is supplied to the regeneration tower, and the exhaust gas flows in a separate system from the product gas from the reaction tank. Therefore, there is no problem that the product gas is diluted with nitrogen.

  Moreover, in another preferable aspect of the present invention, a step of recovering at least a part of the generated heat and / or waste heat in the regeneration zone and effectively using the recovered heat may be included. The heat recovered in this way can be effectively used for drying and heating of biomass raw materials, generation of water vapor as a gasifying agent, and the like.

  As described above, in the present invention, by effectively fluidly contacting the solid pulverized gasification accelerator, firstly, the polymer and the pyrolysis product of biomass released to the gas phase are promptly decomposed. It is effective in that it can be used, but it is not only that, but also a heat transfer medium that conveys the energy required for the reaction to the biomass by heat conduction from the contact between the biomass and the gasification accelerator and radiation from the gasification accelerator. However, this gasification accelerator is presumed to have an important effect. Furthermore, when operating at a relatively low temperature, the carbon generated as a by-product is adsorbed on the catalyst surface, and the heat generated as the by-product char adsorbed in the regeneration tower burns is transferred to the reaction zone. There is also a function to heat biomass. The multifaceted action of such gasification accelerators dramatically improves the heat balance of the gasification reaction process, enabling efficient production of methanol synthesis gas under mild temperature and pressure conditions. It becomes.

  The present invention includes a method for producing a liquid fuel such as methanol from the useful raw material gas obtained by the method as described above. Specifically, after adjusting the components of the product gas obtained in the above process with a shift reactor if necessary, carbon dioxide is removed with a carbon dioxide removal device, and then methanol is synthesized by a catalytic reaction in a methanol synthesis device. can do. Therefore, a method for synthesizing gaseous fuel or methanol from the obtained product gas can be appropriately carried out by known means.

  In the present invention, since the gasification accelerator to be used is made of clay, a mixture of waste catalyst (clay) and ash discarded after the reaction can be directly reduced to the soil and effectively used as a soil conditioner. Is possible. In particular, the use of such soil conditioners is useful when there is a concern that the soil will gradually reduce fertility / productivity by continuing to collect biomass. Use of such waste as a soil conditioner is preferable for improving acidic soil and supplying mineral components to the soil, and depending on the properties of the soil to be reduced, the soil can be improved by improving the nutrient adsorption and water retention capacity of clay. It is also possible to increase the productivity of itself.

  Furthermore, in the present invention, the useful gas obtained by carrying out the above gasification method can be used as a gaseous fuel as it is.

A cylindrical stainless steel container having a diameter of 1.1 m and a height of 2.5 m is divided into two semicylindrical containers by dividing them in half with a stainless steel partition wall, and each of them is used as a gasification furnace and a regeneration tower. Gasification was performed. The outside of the cylinder was covered with a heat insulating material. An acid-treated kaolin clay (particle size: 100 to 300 μm) was used as the fluid medium and circulated between the gasifier and the regeneration tower. Biomass was charged into the gasifier and gasified with steam in the presence of a clay catalyst. The clay catalyst adsorbing the carbonaceous by-product is circulated to the regeneration tower, air is blown into the regeneration tower, the adsorption by-product is burned and removed to regenerate the clay catalyst, and the regenerated clay catalyst is gasified again. It was circulated to. In order to maintain the heat balance of the entire system, some biomass was also injected into the regeneration tower as fuel. As a result, as shown in Table 1, a gas with a high calorific value was obtained. The temperature of the regeneration tower needs to be 150 to 200 ° C. higher than the temperature of the gasification furnace when the gasification furnace and the regeneration tower are separated, whereas the gasification furnace and the regeneration tower are adjacent to each other. By making both the partition walls have high heat transfer properties, the temperature could be reduced to 75 ° C. higher than that of the gasifier. In addition, when the gasification furnace and the regeneration tower are separated, the temperature of both fluctuates periodically and is difficult to adjust, whereas in the method of the present invention, the fluctuation of those temperatures remains minute, Stable operation became possible.

Sectional drawing which shows the basic composition of the apparatus for enforcing the gasification method of biomass by this invention.

Explanation of symbols

1 Gasification Reaction Zone 2 Regeneration Zone 3 Bulkhead 4 Cyclone

Claims (5)

A gasification reaction zone and a regeneration zone are provided, a gasification accelerator having a catalytic function and / or a heat medium function is circulated between the two, and an organic substance containing biomass is introduced into the gasification reaction zone to provide a gasifying agent and a gas. Gasification is carried out in the presence of a gasification accelerator, and the gasification accelerator with adsorption by-products such as carbon deposited on the surface is introduced into the regeneration zone, and the adsorption by-product attached to the gasification accelerator is burned in the regeneration zone. Or a method of biomass gasification comprising a step of recycling the gasification accelerator in a heated state, which is removed by partial combustion and carbonaceous gasification reaction, and regenerated in this manner, to the gasification reaction zone. ,
The gasification reaction zone and the regeneration zone are adjacent to each other via a partition wall having thermal conductivity, and heat transfer by radiation, conduction, and convection from the regeneration zone to the gasification reaction zone is performed via the partition wall. Thus, the temperature of the regeneration zone is reduced as compared with the case where there is no such heat transfer, and the automatic temperature control function of the apparatus for gasification is enhanced. Gasification method.   The temperature conditions in the gasification reaction zone and the regeneration zone are 400 ° C. to 800 ° C., preferably 400 ° C. to 750 ° C., more preferably 450 ° C. to 600 ° C. in the gasification reaction zone. The process according to claim 1, comprising relatively mild conditions in the temperature range of 25 ° C to 300 ° C higher than the reaction zone, preferably 25 ° C to 200 ° C higher, more preferably 25 ° C to 150 ° C higher.   The gasification accelerator in the gasification comprises at least one selected from the group consisting of smectite clay, vermiculite clay, kaolin-serpentine clay, chlorite clay, and mixtures thereof. the method of.   The method according to claim 1, wherein the gasifying agent in the gasification includes water vapor.   The wall length separating the gasification reaction zone and the regeneration zone is 20% or more, preferably 30% or more, more preferably 40%, with respect to the circumferential length of the horizontal section of the fluidized bed portion of the gasification reaction zone. 2. The method according to claim 1 occupying the above.

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