JP2006328326A - Method and system for gasifying biomass - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and system for gasifying a biomass and its operation process that does not need to have a drying machine, can reduce the amount of the steam being extracted from a gasifying furnace and mixed with a pyrolysed gas, and hence can achieve space-saving and cost reduction. <P>SOLUTION: The system for gasifying a biomass comprises a gasifying furnace 3, that produces a pyrolysed gas in the outlet side 3b of the furnace by the thermal cracking of a biomass as a raw material flowing from inlet side 3a toward outlet side 3b, and an extracting equipment settled at the inlet side 3a of the gasifying furnace 3 for extracting the steam generated in the furnace. The extracting equipment is connected with a hot blast producer for providing the gasifying furnace 3 with heat and the steam generated in the furnace is introduced into the equipment. The gasifying furnace 3 is equipped with a baffle 19 to control the flow of the atmosphere in the furnace between the outlet side 3b where the pyrolysed gas is exhausted and the inlet side 3a where the steam generated in the furnace is extracted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a biomass gasification method capable of reducing the amount of water vapor mixed in the pyrolysis gas extracted from the gasification furnace without installing a dryer, and achieving space saving and cost reduction. It relates to a biomass gasification system.

  Conventionally, various biomass such as wood chips, cow dung, and chicken dung is used as a raw material, and the raw material biomass is heat-treated in a gasification furnace using heat supplied from a combustion heat source to generate a pyrolysis gas as a fuel gas. A biomass gasification system is known in which the pyrolysis gas is supplied to a gas engine to generate power (see, for example, Patent Document 1).

  FIG. 8 shows a conventional configuration of the biomass gasification system a. The raw material biomass is input to the receiving hopper b, and the input raw material biomass is input to the dryer d via the conveyor c. The dryer d dries the raw material biomass. The dried raw material biomass is then charged into the inlet side f of the gasification furnace e. For example, an externally heated rotary kiln type is known as the gasification furnace e. The gasification furnace e heats and decomposes the raw material biomass with hot air generated in the hot air generator h, which is a combustion heat source, while flowing the raw material biomass from the inlet side f to the outlet side g. Is generated. The generated pyrolysis gas is reformed in the gas reforming tower i, sent to the gas cooling tower k through the filter dust collector j, and then sent to the gas engine m to be consumed as fuel. Is done. The gas engine m drives the generator n to generate electricity to enable electricity to be acquired, hot water is acquired from the engine cooling water, and steam is acquired by the boiler p by using the exhaust gas from the gas engine m. Is done.

  In particular, in the prior art, as described above, the dryer d is installed in the front stage of the gasification furnace e. Usually, in the gasification furnace e of the biomass gasification system a, the raw material biomass is transferred from the inlet side f toward the outlet side g while flowing, and is heated during this transfer. At the inlet side f of the gasification furnace e, the charged raw material biomass stays and stays at a relatively low temperature. On the other hand, at the outlet side g of the gasification furnace e, the fluidity of the raw material biomass is increased and it is in a high temperature state. Therefore, in the gasification furnace e exhibiting such a temperature distribution, as shown in FIG. 9, pyrolysis gas (indicated by a broken line in the figure) is actively generated at the outlet side g, while the gasification furnace e On the inlet side f, the raw material biomass is steamed and water vapor (shown by a solid line in the figure) is generated, and particularly a high water content raw material biomass generates a very large amount of water vapor. Then, the steam is mixed with the pyrolysis gas generated at the outlet side g and extracted from the gasification furnace e, and a high-temperature treatment is performed up to a large amount of water vapor in the gas reforming tower i downstream of the gasification furnace d. Thus, there is a problem that a great amount of energy loss is caused.

Therefore, a dryer d that dries the raw material biomass is installed in the front stage of the gasification furnace e, and moisture content is previously removed by the drier d to reduce the water content of the raw material biomass, thereby extracting from the gasification furnace e. The amount of water vapor in the pyrolysis gas to be reduced is reduced to reduce the amount of processing gas in the gas reforming tower i arranged at the rear stage of the gasification furnace e, and energy loss (pyrolysis gas consumption) due to partial combustion is also reduced. I tried to reduce it. Further, the exhaust gas containing water vapor generated in the drying process in the dryer d is discharged outside the system by the suction fan q connected to the dryer d.
JP 2004-352960 A

  By the way, it has been conventionally provided with a dryer d, and for that purpose, installation space and equipment costs for the dryer d are required, which leads to an increase in equipment scale and cost of the biomass gasification system a. There has been a problem, and it has been desired to devise a method and apparatus that can reduce the amount of water vapor mixed in the pyrolysis gas extracted from the gasification furnace e without providing the dryer d.

  The present invention was devised in view of the above conventional problems, and it is possible to reduce the amount of water vapor mixed into the pyrolysis gas extracted from the gasification furnace without the need for installing a dryer. It aims at providing the biomass gasification processing method and biomass gasification system which can achieve space-ization and cost reduction.

  In the biomass gasification method according to the present invention, by heating and pyrolyzing the raw material biomass flowing from the inlet side toward the outlet side, from the inlet side of the gasification furnace where pyrolysis gas is generated on the outlet side, The method includes a step of extracting steam in the furnace.

  The extracted in-furnace water vapor is preferably introduced into a combustion heat source that supplies heat to the gasification furnace.

  The extraction amount of the steam in the furnace is desirably set according to the water content of the raw material biomass.

  The amount of steam extracted from the furnace is preferably set according to the amount of power generated by the gas engine operated with the pyrolysis gas generated in the gasifier.

  The biomass gasification system according to the present invention includes a gasification furnace in which pyrolysis gas is generated on the outlet side by heating and pyrolyzing the raw material biomass flowing from the inlet side toward the outlet side, and the gas And an extraction facility for extracting steam in the furnace.

  It is preferable that the extraction facility is connected to a combustion heat source that supplies heat to the gasification furnace and introduces in-furnace water vapor thereto.

  The gasification furnace is preferably provided with a baffle that suppresses the flow of the furnace atmosphere between the outlet side where the pyrolysis gas is generated and the inlet side where the steam in the furnace is extracted.

  In the biomass gasification method and the biomass gasification system according to the present invention, the amount of water vapor mixed in the pyrolysis gas extracted from the gasification furnace can be reduced without the need for installing a dryer. Space saving and cost reduction can be achieved.

  Hereinafter, a preferred embodiment of a biomass gasification method and a biomass gasification system according to the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the biomass gasification system 1 according to the present embodiment basically transports a raw material biomass charged into the receiving hopper 2 and the raw material biomass discharged from the receiving hopper 2 to the gasification furnace 3. Conveying system 4 to be introduced to the inlet side 3a, and external heat that heats and thermally decomposes the raw material biomass to generate pyrolysis gas while flowing the raw material biomass charged to the inlet side 3a toward the outlet side 3b The rotary kiln type gasifier 3 is connected to the gasifier 3, and oxygen is introduced from the oxygen generator 5 to remove tar content in the pyrolysis gas extracted from the gasifier 3, etc. A gas reforming tower 6 for reforming the pyrolysis gas, a filtration dust collector 7 connected to the gas reforming tower 6 for removing dust and the like in the reformed pyrolysis gas sent, and a filtration collection Jin machine 7 A gas cooling tower 8 that is connected and cools for the purpose of cleaning the pyrolysis gas, and a gas engine 9 that is connected to the gas cooling tower 8 and is operated using the purified pyrolysis gas as fuel. Is done.

  The gas engine 9 drives a generator 10 to generate electricity and thereby acquire electricity, and hot water is acquired by the cooling system 11 of the gas engine 9, and a boiler 12 that uses the exhaust gas of the gas engine 9. Steam is acquired.

  On the other hand, the gasification furnace 3 is connected via a circulation system 13 to a hot air generation furnace 14 that is a combustion heat source. The hot air generating furnace 14 generates hot air by, for example, combusting the residue of the raw material biomass carried out from the gasification furnace 3 through the residue carrying-out system 15, and this hot air flows into the gasification furnace 3 through the circulation system 13. It is circulated and used for heat treatment of raw material biomass.

  The heat treatment for generating pyrolysis gas in the gasification furnace 3 is the same as in the prior art, and as shown in FIG. 2, the input raw material biomass is deposited on the inlet side 3a of the gasification furnace 3. The outlet side 3b stays at a relatively low temperature, and on the other hand, the fluidity of the raw material biomass is increased and the high temperature. Therefore, the raw material biomass is steamed when the inlet side 3a is about 100 ° C. (Shown by a solid line in the figure) is an evaporation area where a large amount is generated, the outlet side 3b is about 700 ° C., and a pyrolysis area where pyrolysis gas (shown by a broken line in the figure) is actively generated from raw biomass Become.

  In the present embodiment, an extraction facility 16 for extracting the in-furnace water vapor from the gasification furnace 3 is provided on the inlet side 3a of the gasification furnace 3, which is an evaporation region where a large amount of water vapor is generated. The extraction facility 16 includes an extraction piping system 17 and an induction blower 18 that is provided in the extraction piping system 17 and sucks the atmosphere in the gasification furnace 3. In the present embodiment, one end of the extraction piping system 17 is connected to the inlet side 3 a of the gasification furnace 3, the other end is connected to the hot air generating furnace 14, and the steam in the furnace is introduced into the hot air generating furnace 14. It has come to be. The other end of the extraction piping system 17 may be simply opened to the atmosphere via a gas purification processing device or the like. However, by connecting to the hot air generating furnace 14, the odor contained in the extraction of the steam in the furnace and the slight pyrolysis gas sucked with the suction of the steam in the furnace are separately gas-purified. Appropriate processing can be performed without the need to install a device or the like.

  It is preferable that the amount of steam in the furnace extracted by the extraction facility 16 is basically set according to the water content of the raw material biomass. The water content may be obtained directly by measuring the water content or by measuring the water content ratio and multiplying this by the raw material biomass amount. Before the gasification furnace 3 is charged, the water content of the raw material biomass is obtained in advance, and as the amount of water vapor corresponding to the water content is generated, the furnace atmosphere is sucked in an amount corresponding to the generated amount. The operation of the induction fan 18 is set. What is necessary is just to make into operation time, suction strength, etc. as a setting content of driving | operation.

  Further, the extraction amount of the in-furnace water vapor may be set according to the power generation amount by the gas engine 9. That is, a required amount of raw material biomass is calculated from the amount of pyrolysis gas to be supplied to the gas engine 9 in order to obtain the required amount of power generation, and the amount of generated water vapor is calculated from the calculated amount of raw material biomass. The operation of the induction blower 18 may be set so as to extract an appropriate amount of furnace atmosphere. If it does in this way, it will also become possible to operate the extraction equipment 16 and by extension, the biomass gasification system 1 so that the electric power generation amount by the gas engine 9 may become the largest.

  In the present embodiment, the atmosphere in the furnace flows in the gasification furnace 3 between the outlet side 3b where the pyrolysis gas is generated and the inlet side 3a where the steam in the furnace is extracted. The baffle 19 which suppresses is provided. The baffle 19 is preferably provided around the boundary between the steam region and the pyrolysis region. In addition, the baffle 19 partially restricts the flow of the atmosphere in the furnace, and guarantees the flow of the raw material biomass from the inlet side 3a to the outlet side 3b in the gasification furnace 3, partially at the inlet side 3a and the outlet side 3b. It is preferable to provide a communication unit 20 that communicates with each other. Various examples of the baffle 19 are shown in FIGS.

  The baffle 19 shown in FIG. 3 is, for example, a circular plate 21 and an outer peripheral edge of the plate 21 that are spaced apart from each other along the circumferential direction and project outward in the radial direction. 3, a plurality of projections 22 joined to the inner surface, and the inside of the gasification furnace 3 is partitioned by the plate 21, and the circumferential direction of the plate 21 is between the inner surface of the gasification furnace 3 and the plate 21 by the plurality of projections 22. A plurality of communication portions 20 are defined along the line.

  The baffle 19 shown in FIG. 4 is, for example, a circular plate 23, sleeves 24 provided at equal intervals along the circumferential direction of the outer periphery of the plate 23, and slidably inserted through the sleeves 24. The base end is joined to the inner surface of the gasification furnace 3, and is composed of a rod 25 that slidably supports the plate 23 to the gasification furnace 3, and in the gasification furnace 3 by the plate 23 in substantially the same manner as the baffle 19 of FIG. An annular communication portion 20 is defined between the inner surface of the gasification furnace 3 and the plate 23. In particular, the sleeve 24 is slidable with respect to the rod 25, so that the thermal expansion deformation of the plate 23 can be absorbed.

  The baffle 19 shown in FIG. 5 uses a circular plate 26 having an outer dimension that comes into contact with the inner surface of the gasification furnace 3, and a notch 27 is formed at one circumferential direction of the plate 26. The plate 26 is disposed so that the notch 27 is located on the side from the bottom of the gasification furnace 3 and is joined to the inner surface of the gasification furnace 3. Even in the baffle 19, the communication portion 20 is partitioned by the notch portion 27 while partitioning the gasification furnace 3 by the plate 26 in substantially the same manner as the baffle 19 of FIG. 3. The baffle 19 shown in FIG. 5 is excellent in that it is very simple.

  The baffle 19 shown in FIGS. 6 and 7 is attached to the shaft 28 disposed at the axial center position of the gasification furnace 3 from the inlet side 3 a toward the outlet side 3 b, and is attached to the inner surface of the gasification furnace 3. And a screw-like blade 29 that is in contact with the blade. The number of blades 29 can be arbitrarily set. The blades 29 may be bonded to the inner surface of the gasification furnace 3 in advance, but may be set so as to contact the inner surface of the gasification furnace 3 by thermal expansion. The spiral communication portion 20 is defined by the blade 29 around the shaft 28. On the other hand, in the baffle 19, as shown in FIG. 6, when the raw material biomass reaches the height dimension of the blades 29 or more, in other words, corresponds to the arrangement height position of the shaft 28, the material by the raw material biomass itself. A seal can be formed, whereby the gasification furnace 3 can be completely partitioned. According to the baffle 19, while the smooth flow of the raw material biomass in the gasification furnace 3 is ensured by the spiral communication part 20, the flow of the atmosphere in the furnace is performed using the raw material biomass staying in the communication part 20. It can be almost completely blocked and provides extremely good performance.

  In any of the baffles 19, the atmosphere in the furnace freely flows and the pyrolysis gas mixes with the water vapor on the gasifier inlet side 3a while ensuring the flow of the raw material biomass to the gasifier outlet side 3b. Can be suppressed.

  Next, the biomass gasification method according to this embodiment will be described. First, the water content of the raw material biomass input to the gasification furnace 3 is measured, and the operation of the induction blower 18 of the extraction facility 16 is set based on this. Then, raw material biomass is thrown into the gasification furnace 3, hot air is circulated and supplied from the hot air generation furnace 14, and the production | generation process of pyrolysis gas is started. The raw material biomass charged into the inlet side 3a of the gasification furnace 3 sequentially flows to the outlet side 3b through the communication part 20 of the baffle 19, and the raw material biomass is heated and thermally decomposed along with this, Pyrolysis gas is actively generated at the outlet side 3b. At this time, the in-furnace water vapor generated on the inlet side 3 a of the gasification furnace 3 is extracted by the extraction equipment 16. In this extraction, the baffle 19 suppresses the flow of the pyrolysis gas generated on the outlet side 3b of the gasification furnace 3 to the inlet side 3a.

  Therefore, the pyrolysis gas generated in the gasification furnace 3 is sent out of the gasification furnace 3 with little water vapor, and passes through the gas reforming tower 6, the filtration dust collector 7, and the gas cooling tower 8. It is sent to the gas engine 9 and used as fuel for the gas engine 9. On the other hand, the in-furnace atmosphere mainly composed of in-furnace water vapor extracted from the extraction facility 16 is introduced into the hot air generating furnace 14 and subjected to combustion treatment.

  In the biomass gasification processing method and biomass gasification system according to the present embodiment described above, an extraction facility 16 is provided on the inlet side 3a of the gasification furnace 3, and the inlet of the gasification furnace 3 by this extraction facility 16 is provided. Since the in-furnace water vapor is extracted from the side 3a, the in-furnace water vapor generated on the inlet side 3a of the gasification furnace 3 in the pyrolysis gas generation process is not mixed with the pyrolysis gas generated on the outlet side 3b. Thus, it can extract efficiently. As a result, the amount of water vapor mixed in the pyrolysis gas extracted from the gasification furnace 3 can be reduced without the need for installing a dryer. Can be achieved.

  Since only the steam in the furnace of the gasification furnace 3 can be extracted in this way, only almost all of the generated pyrolysis gas can be sent to the gas reforming tower 6 and the like at the rear stage of the gasification furnace 3. Compared with the case where a dryer is installed, the amount of processing gas in the gas reforming tower 6 can be reduced, energy loss due to partial combustion can be reduced, and the equipment performance of the biomass gasification system 1 can be reduced. Can be improved.

In order to compare and examine the case where water vapor is extracted from the inlet side 3a of the gasification furnace 3 and the case where water vapor is not extracted, the following conditions;
(1) Raw material biomass shall be wood chips with a moisture of 50% (2) Carbide generation rate of raw material biomass shall be 0.3 kg / kg (dry) (3) Pyrolysis gas temperature at the gasifier 3 outlet (4) The outlet gas temperature of the hot air generator 14 is 950 ° C. (5) The raw material from the inlet side of the gasifier 3 It is assumed that the biomass-derived water vapor is extracted 100% (6) The processing temperature of the gas reforming tower 6 is 1100 ° C. (7) The power generation efficiency of the gas engine 9 is constant at 30%. After numerical analysis,
(1) Since the amount of gas discharged from the gasifier is reduced by the extraction of water vapor, the amount of oxygen used in the gas reforming tower 6 can be reduced by about 62%, and thus the oxygen generator 5 can be reduced in size and cost. (2) The cold gas efficiency is improved by about 13%. The amount of power generation is improved by about 17%, the amount of steam is improved by about 91%, the amount of hot water is improved by about 17%, and the total amount of recovered energy is improved by about 17%. (4) Since the amount of process gas from the gasification furnace 3 outlet is reduced by the extraction of water vapor, the equipment price of the gas reforming tower 6, the oxygen generator 5, the gas cooling tower 8, and the filter dust collector 7 is reduced. As a result, it was possible to reduce by half, and the advantage of extracting water vapor from the inlet side 3a of the gasification furnace 3 was confirmed.

  Further, since the extraction facility 16 is connected to the hot air generating furnace 14 and the extracted steam in the furnace is introduced into the hot air generating furnace 14, the odor and pyrolysis gas are removed by the combustion action in the hot air generating furnace 14. In-furnace water vapor that can be contained can be appropriately treated.

  Further, since the baffle 19 is provided in the gasification furnace 3, it is possible to suppress the flow of the furnace atmosphere between the outlet side 3b where the pyrolysis gas is generated and the inlet side 3a where the steam in the furnace is extracted. Thus, it is possible to prevent the steam generated on the inlet side 3a and the pyrolysis gas generated on the outlet side 3b from mixing with each other in the gasification furnace 3, and in particular by the action of extracting steam from the inlet side 3a. While it is possible to appropriately prevent the pyrolysis gas on the outlet side 3b from flowing into the inlet side 3a and to effectively extract water vapor from the gasification furnace 3 with the extraction facility 16, almost all of the generated pyrolysis gas is removed. The gas can be supplied to the gas reforming tower 6 and eventually to the gas engine 9.

  Furthermore, since the extraction amount of the steam in the furnace is set according to the water content of the raw material biomass or set according to the amount of power generated by the gas engine 9, the amount of steam necessary for removal is appropriately gasified. It can be extracted from the furnace 3.

1 is a schematic system diagram showing a preferred embodiment of a biomass gasification processing method and a biomass gasification system according to the present invention. It is explanatory drawing for demonstrating the relationship between the distribution state of the raw material biomass in the gasification furnace of the biomass gasification system shown in FIG. 1, and the raw material biomass temperature in a gasification furnace. It is front sectional drawing of the gasification furnace which shows an example of the baffle applied to the biomass gasification system shown in FIG. It is front sectional drawing of the gasification furnace which shows the other example of the baffle applied to the biomass gasification system shown in FIG. It is front sectional drawing of the gasification furnace which shows the further another example of the baffle applied to the biomass gasification system shown in FIG. It is front sectional drawing of the gasification furnace which shows the further another example of the baffle applied to the biomass gasification system shown in FIG. It is a side view of the baffle shown in FIG. It is a schematic system diagram which shows the conventional biomass gasification system. It is a sectional side view of the gasification furnace which shows the state in the gasification furnace of the biomass gasification system shown in FIG.

Explanation of symbols

3 Gasification furnace 3a Gasification furnace inlet side 3b Gasification furnace outlet side 9 Gas engine 14 Hot air generator 16 Extraction equipment 19 Baffle

Claims (7)

  Heating the raw material biomass flowing from the inlet side toward the outlet side and thermally decomposing it, thereby providing a step of extracting steam in the furnace from the inlet side of the gasification furnace where pyrolysis gas is generated on the outlet side. A biomass gasification method characterized by the above.   2. The biomass gasification method according to claim 1, wherein the extracted steam in the furnace is introduced into a combustion heat source that supplies heat to the gasification furnace.   The biomass gasification method according to claim 1 or 2, wherein an extraction amount of the steam in the furnace is set according to a water content of the raw material biomass.   The biomass gasification according to claim 1 or 2, wherein an extraction amount of the steam in the furnace is set according to a power generation amount by a gas engine operated with a pyrolysis gas generated in the gasification furnace. Processing method.   By heating and pyrolyzing the raw material biomass flowing from the inlet side toward the outlet side, a gasification furnace in which pyrolysis gas is generated on the outlet side, and the steam in the furnace provided on the inlet side of the gasification furnace A biomass gasification system comprising an extraction facility for extracting sucrose.   The biomass gasification system according to claim 5, wherein the extraction facility is connected to a combustion heat source that supplies heat to the gasification furnace and introduces steam in the furnace into the combustion heat source.   The gasification furnace is provided with a baffle that suppresses the flow of the furnace atmosphere between the outlet side where the pyrolysis gas is generated and the inlet side where the steam in the furnace is extracted. Item 7. The biomass gasification system according to Item 5 or 6.

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