JP2008222978A - Wood charcoal gasification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and inexpensive gas purification process for removing tar and the like in a produced gas produced through gasification of wood charcoal by pyrolysis or the like. <P>SOLUTION: A wood charcoal gasification apparatus comprises a gasification furnace 5 for subjecting wood charcoal to pyrolysis by partially combusting wood charcoal and gasifying wood charcoal through an aqueous gasification reaction by supplying water vapor, a cooling column 13 for producing water vapor to be supplied to the gasification furnace by recovering the heat of a produced gas produced in the gasification furnace, a washing column 15 for purifying by sprinkling water wash on the produced gas cooled in the cooling column, a filter 34 for separating impurities such as tar and the like from water wash extracted from the bottom of the washing column, a circulation pump 32 for circulating water wash discharged from the filter as water wash for use in the washing column, and an adsorption column 36 for subjecting water wash to adsorption treatment by extracting a part of water wash discharged from the filter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a charcoal gasifier, and more specifically to a technology for purifying a generated gas generated by gasifying charcoal by pyrolysis or the like.

  As described in Patent Document 1, as a gasifier, a vertical moving bed gasification furnace or a fixed bed gasification furnace is loaded with, for example, a layer of combustible gasification objects and non-combustible pellets. Then, air is supplied from the bottom side of the gasification furnace to burn a part of the gasification target, the remaining gasification target is pyrolyzed with the combustion heat, and water vapor is supplied from the bottom side to perform an aqueous reaction. It has been proposed to extract the gas (hereinafter referred to as “produced gas”) generated by gasification and use it effectively as, for example, fuel gas.

  By the way, depending on the composition of the gasification target, if the thermal decomposition is not sufficiently performed, dust such as tar and soot is contained in the generated gas. Therefore, according to Patent Document 1, the generated gas discharged from the gasification furnace is guided to the washing and washing tower to condense the water vapor in the generated gas, remove tar and dust, and further discharge from the washing and washing tower. It has been proposed to remove the generated gas mist or the like by wet EP or the like to clean the generated gas.

  On the other hand, it has been studied to gasify biomass fuel such as wood chips and use it as a fuel gas for internal combustion engines, for example, but when biomass fuel such as wood chips is gasified, tar content and soot dust are compared with the produced gas. Therefore, the same gas purification treatment as in Patent Document 1 is required.

JP 2004-2552 A

  However, in Patent Document 1, no consideration is given to the treatment of washing water containing tar and the like removed by the washing tower. In particular, there is room for improving the gas purification process as a whole rational process, including the treatment of gas wash water.

  In particular, recently, there is a demand for gasification of charcoal to be used as a fuel gas for internal combustion engines. However, dust and tar contained in gas generated from gasification of charcoal are converted into gas generated from gasification of other biomass fuels. Since there are few compared with it, realization of a simple and inexpensive gas purification process is desired.

  The problem to be solved by the present invention is to realize a simple and inexpensive gas purification process that removes tars and the like in product gas obtained by gasifying charcoal by pyrolysis or the like.

  In order to solve the above-mentioned problems, a charcoal gasification apparatus of the present invention comprises a gasification furnace for partially combusting charcoal to thermally decompose the charcoal and supplying water vapor to gasify by a water gasification reaction, and the gas A cooling tower that recovers heat of the generated gas generated in the gasification furnace and generates water vapor to be supplied to the gasification furnace; a cleaning tower that sprays cleaning water on the generated gas cooled in the cooling tower to purify A filter that separates impurities such as tar from the wash water extracted from the bottom of the wash tower, a circulation pump that circulates the wash water discharged from the filter as wash water for the wash tower, and the filter And an adsorption tower for extracting and treating a part of the washing water discharged from the tank.

  That is, since the product gas generated by pyrolysis or the like is high in temperature, it is guided to the cooling tower to generate water vapor by the heat of the product gas, and the generated water vapor is used for the water gasification reaction in the gasification furnace. , Heat balance can be improved. Further, when the product gas discharged from the gasification furnace is introduced into the cleaning tower at a high temperature, there is a problem that a large amount of cleaning water is required, so that the cleaning water treatment apparatus becomes large. The amount of washing water can be reduced by the amount of water vapor generated by providing a cooling tower.

  Also, since the tar content and soot in the generated gas obtained by gasifying charcoal is small, impurities such as tar are separated from the washing water extracted from the bottom of the washing tower with a filter, and the washing water is recycled and used. By extracting and treating a part of the washing water, it is possible to reduce the size by using an adsorption tower for washing water treatment.

  In this case, it is preferable that charcoal is used as the adsorbent for the adsorption tower, and when the adsorption capacity is reduced, the charcoal is put into a gasification furnace and gasified. This eliminates the need for the regeneration process of the adsorbent, thereby simplifying and downsizing the gas purification process.

  ADVANTAGE OF THE INVENTION According to this invention, the simple and cheap gas purification process which removes the tar etc. in the product gas obtained by gasifying charcoal by thermal decomposition etc. is realizable.

  Hereinafter, the present invention will be described based on embodiments. In FIG. 1, the whole block diagram of the charcoal gasification apparatus of one Embodiment of this invention is shown.

  As shown in FIG. 1, after the charcoal 1 to be gasified is received in the storage tank 2, the charcoal 1 is put into the hopper portion of the supply device 6 provided at the top of the gasification furnace 5 by the conveyor 4. Yes. The gasification furnace 5 is formed of a bowl-shaped cylindrical container, and is filled with charcoal 1 input from a supply device 6 to a predetermined height. The packed bed of charcoal 1 is supplied with air 7 and steam 8 preheated from the bottom of the furnace so that a portion of the charcoal 1 on the bottom of the furnace is burned by an ignition burner (not shown). It has become. The remaining charcoal 1 is thermally decomposed by the heat of partial combustion of the charcoal 1 and is gasified by water and gasification reaction with water vapor. The product gas passes through the packed bed and rises in the gasification furnace 5 and is discharged out of the furnace through a gas discharge port 9 provided at the top of the furnace. Further, at the bottom of the gasification furnace 5, an exhauster 10 for discharging combustion residues such as ash is provided. The combustion residue discharged from the discharger 10 is put into the residue selector 11 and sieved.

  The product gas 12 discharged from the gasification furnace 5 is introduced into the top of the cooling tower 13. A heat exchange tube 14 is provided in the cooling tower 13, and water is supplied to the heat exchange tube 14 from a water source (not shown). The product gas withdrawn from the bottom of the cooling tower 13 is circulated from the bottom to the top of the washing tower 15, and the washing water sprayed from the sprinkling nozzles 16 provided at the top causes the tar content and water vapor contained in the produced gas to flow. Condensed water and dust are taken into the cleaning water and removed. The product gas extracted from the top of the washing tower 15 is guided to the wet EP 17 to remove mist and the like. The product gas discharged from the wet EP 17 is sucked into the induction blower 18 and stored in the product gas buffer tank 19. The produced gas stored in the buffer tank 19 is appropriately supplied as a fuel gas to the gas engine 20 to drive the generator 21. Exhaust gas from the gas engine 20 is released to the atmosphere via a waste heat recovery boiler 22 and a denitration catalyst tower 23. The buffer tank 19 is connected to a ground flare 24 for burning the generated gas in an emergency.

  Here, the configuration of the gas cleaning apparatus according to the feature of the present embodiment will be described. In the cleaning tower 15, the cleaning water in which the tar content, the condensed water vapor and the dust contained in the generated gas are taken out from the bottom of the cleaning tower 15 is temporarily stored in the cleaning water tank 31. The washing water in the washing water tank 31 is extracted by the circulation pump 32 and flows into the liquid cyclone 33. The hydrocyclone 33 separates relatively large tars and dust contained in the washing water by centrifugal force and discharges it from the bottom. The washing water discharged from the liquid cyclone 33 is guided to the filter 34, and tar and dust that cannot be separated by the liquid cyclone 33 are separated and removed from the washing water. The washing water that has passed through the filter 34 is heated in the heat exchanger 35 and then sprayed into the product gas from the watering nozzle 16 of the washing tower 15.

  Further, a part of the washing water flowing out from the filter 34 is circulated to the adsorption tower 36 and the tar and dust remaining in the washing water are adsorbed and removed by the adsorbent. Here, the charcoal 1 to be gasified is used as the adsorbent. Washing water discharged from the adsorption tower 36 is sucked by a pump 37, filtered through a filter 38, and discharged as clean wastewater.

  With this configuration, according to the present embodiment, the high-temperature (for example, 700 ° C.) product gas 12 discharged from the gasification furnace 5 is introduced into the cooling tower 13 and circulates in the heat exchange tube 14. Water is heated to generate water vapor. This water vapor is used as the water vapor 8 supplied from the gasification furnace 5, and is used for the remaining heat of the air 7 that is guided to the heat exchanger 39 and supplied from the gasification furnace 5. As described above, the air 7 and the water vapor 8 used in the gasification furnace 5 are heated by the heat of the product gas 12 before the product gas 12 is introduced into the washing tower 15 and the washing water is sprayed for cooling and condensation. Therefore, the heat balance of the gas purification process can be improved by making effective use of heat.

  Further, the product gas 12 is cooled by the cooling tower 13 to become a low temperature (for example, 200 ° C.), and further cooled by the washing water introduced into the washing tower 15 and sprayed from the water spray nozzle 16. As a result, the tar content and water vapor contained in the product gas are condensed, and dust is taken into the washing water to purify the product gas. In this case, when the product gas 12 discharged from the gasification furnace 5 is introduced into the cleaning tower 15 at a high temperature, a larger amount of cleaning water is required. According to this embodiment, the cooling tower 13 is provided to Since the amount of cleaning water can be reduced by the amount recovered, there is an effect that the cleaning water treatment device is reduced in size.

  In addition, since the tar content and soot in the generated gas obtained by gasifying charcoal are small, impurities such as tar are separated from the washing water extracted from the bottom of the washing tower 15 by the liquid cyclone 33 or the filter 34, thereby providing washing water. Can be used cyclically. As a result, a part of the circulated washing water is extracted and adsorbed by the adsorption tower 36, so that the washing liquid can be purified. Therefore, the washing water treatment amount can be greatly reduced and the washing water treatment apparatus can be reduced in size. Can be

  Furthermore, if charcoal is used as the adsorbent for the adsorption tower 36 and the adsorption capacity is reduced, the adsorbent regeneration process is not required if the gasification is performed by introducing the charcoal into the gasification furnace 5. The purification process can be further simplified and miniaturized.

  As described above, according to the present embodiment, a gas purification process for removing tar and the like in product gas obtained by gasifying charcoal by pyrolysis or the like can be realized simply and inexpensively.

  That is, according to the prior art, in order to treat a large amount of washing water obtained by washing the produced gas obtained by gasifying biomass fuel such as wood chips, a large and complicated washing water treatment apparatus is required. For example, an apparatus for separating tar and the like from the washing water discharged from the washing tower, an apparatus for incinerating the separated tar and the like, or a purification treatment using a biological treatment apparatus or activated carbon adsorption is required.

It is a whole block diagram of the charcoal gasification apparatus of one Embodiment of this invention.

Explanation of symbols

5 Gasification furnace 13 Cooling tower 14 Heat transfer tube 15 Washing tower 16 Sprinkling nozzle 17 Wet EP
31 Washing Water Tank 32 Circulation Pump 33 Hydrocyclone 34 Filter 35 Heat Exchanger 36 Adsorption Tower 38 Filter 39 Heat Exchanger

Claims (2)

  The charcoal is pyrolyzed by partially burning charcoal, and the gasification is performed by supplying water vapor to gasify by a water gasification reaction, and recovering the heat of the generated gas generated in the gasification furnace A cooling tower that generates water vapor to be supplied to the chemical furnace, a cleaning tower that sprays cleaning water on the product gas cooled in the cooling tower to purify, a cleaning tower that is extracted from the bottom of the cleaning tower, such as tar A filter that separates impurities, a circulation pump that circulates wash water discharged from the filter as wash water for the wash tower, and an adsorption tower that extracts and processes part of the wash water discharged from the filter A charcoal gasifier comprising: In claim 1,
The charcoal gasifier is characterized in that the adsorption tower uses charcoal to be gasified as an adsorbent, and when the charcoal adsorption capacity is reduced, the charcoal is put into the gasifier and gasified.

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