JP2005255787A - Method for gasifying waste material and device for gasifying waste material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a tar content in produced gas and floating materials accompanying with the gas, and also improving gasification efficiency. <P>SOLUTION: This method for gasifying the waste materials by forming a filled layer by putting waste materials into a gasification oven 3, feeding an oxidizing agent gas from the lower direction of the filled layer to partially burn the waste materials, gasifying the waste materials by the heat of combustion, and also drawing out combustion residue from the filled layer for treating the waste materials continuously is provided by flowing the produced gas through an adsorbing column filled with non-burning pellets 39, by putting the non-burning pellets 39 in the gasification oven 3 for treating, adsorbing and removing the tar content in the produced gas and floating materials accompanying with the produced gas with the non-burning pellets 39 to clean the produced gas and decomposing the adsorbed tar content to hydrogen, carbon monoxide, etc., in the gasification oven 3 for the effective gasification. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a waste gasification method and a waste gasification apparatus.

  As a method for treating waste, the waste is put into a gasification furnace to form a packed bed, and an oxidant gas such as air is supplied from the bottom to cause partial combustion, and the combustion zone and pyrolysis zone in the furnace height direction. In addition, a moving bed type waste gasification furnace has been proposed in which a dry zone is formed, a product gas is extracted from the upper part, and a residue generated by gasification is extracted from the furnace bottom to continuously treat waste ( For example, see Patent Document 1). According to this, the waste in the drying zone can be dried by the heat of the product gas, and the oxidant gas can be preheated by the heat of the combustion residue at the bottom of the furnace, which is efficient. Further, since the tar content in the product gas cools and condenses in the process in which the product gas rises in the drying zone, it adheres to the waste and is removed, so that a relatively clean product gas can be obtained.

JP 2000-517409 (see FIG. 1, page 5)

  However, since the drying zone is maintained at a relatively high temperature by the heat of the product gas, the tar content having a dew point lower than the drying temperature cannot be condensed and attached to the waste. Therefore, the tar component having a dew point lower than the drying temperature passes through the drying zone in the gas phase and is supplied together with the product gas to the use device of the product gas on the downstream side. This causes a problem that the tar content is condensed on the wake side and clogs the gas pipe. If the equipment used is a combustion engine such as a gas turbine, the combustion may be adversely affected. In addition, the generated gas includes, for example, dust, sawdust, ash, toner and milling, waste thread, glass wool such as heat insulating material, pieces of paper, vinyl thin film pieces, shells, and the like from the bottom of the gasification furnace. In some cases, suspended solids such as combustion ash are accompanied.

  In addition, the combustion residue flowing down from the combustion zone may contain incombustible solids that are larger than the particulates and, in some cases, unburned solids, in addition to the particulates such as ash. In this combustion residue zone, if there is a bias in the cross-sectional distribution of the solid, a difference occurs in the flow resistance of the oxidant gas depending on the cross-sectional portion, and a bias in the flow distribution occurs. Due to this deviation in the flow rate of the oxidant gas, there is a problem in that the combustion in the combustion zone varies and the gasification efficiency due to thermal decomposition or the like decreases.

  An object of the present invention is to remove the tar content of the product gas and suspended substances accompanying the product gas and improve the gasification efficiency.

  The present invention solves the above problems by the following means. That is, the waste is put into the gasification furnace to form a packed bed, the oxidant gas is supplied from below the packed bed to partially burn the waste, and the waste heat is gasified with the combustion heat, In a waste gasification method in which the residue generated by gasification is extracted from below the packed bed and the waste is continuously processed, the generated gas is purified through an adsorption tower filled with noncombustible particles, and the adsorption tower The incombustible particles are put into a gasification furnace and processed.

  According to this, the tar content in the product gas and the suspended substance accompanying the product gas can be adsorbed and removed by the incombustible particles. Therefore, it is possible to prevent the occurrence of clogging of the gas pipe line or combustion failure caused by the tar content in the generated gas. In addition, by introducing incombustible particles that have adsorbed tar content, etc. into the gasifier, when the incombustible particles flow with the waste through the pyrolysis zone or combustion zone, It can be decomposed into carbon monoxide and effectively gasified. In addition, the tar content which was not decomposed | disassembled in a thermal decomposition zone is burned in a combustion zone. The non-combustible particles that have passed through the combustion zone in this way are dispersed in the combustion residue at the bottom of the furnace, improving the bias in the flow of oxidant gas due to solids such as incombustibles and forming a stable combustion zone. Gasification efficiency by thermal decomposition or the like is improved.

  Further, if the non-combustible particles are formed of a porous material, the surface area can be increased, so that the adsorption amount of tar can be increased. Further, if the non-combustible particles are composed of a substance containing alumina, alumina acts as a catalyst in the thermal decomposition zone, and the decomposition of substances such as tar is promoted.

  A waste gasification apparatus that realizes the method of the present invention includes a container, a waste inlet formed in an upper part of the container, a gas supply port of an oxidant gas formed in a lower part of the container, and a lower part of the container A gasification furnace having an extraction port for combustion residues formed in the adsorption tower filled with incombustible particles for allowing the product gas to flow, and the upper part of the container by extracting the incombustible particles in the adsorption tower It is possible to have a configuration provided with a charging means for charging the battery.

  In addition, the waste gasifier is provided with an adsorption tower connected to an opening formed in the top wall of the container, a disk disposed in the container with the input means facing the opening, and a rotational drive for rotating the disk. The disk is formed larger than the opening of the top wall of the container, and the upper surface is formed with a protrusion having a predetermined angle with respect to the radial direction of the disk. it can. Here, the size of the disk and the distance between the disk and the opening are set so that the non-combustible particles do not fall when the rotation of the disk is stopped. For example, the angle of repose of the non-combustible particles is taken into consideration. To do.

  According to the present invention, the tar content in the product gas and the suspended substances accompanying the product gas can be removed and the gasification efficiency can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a vertical moving bed type gasification furnace according to an embodiment to which the present invention is applied. FIG. 2 is an overall view of an embodiment of a waste gasification apparatus to which the present invention is applied. It is a block diagram. Here, although the waste gasification apparatus of this embodiment is used suitably for gasification of a general waste, an industrial waste, biomass, etc., it is not limited to these.

  As shown in FIG. 2, the waste gasifier according to this embodiment includes a waste hopper 1 and a gasification furnace 3. The waste hopper 1 is formed in a cylindrical vertical shape, and the waste 2 crushed from a pretreatment device (not shown) is input into the waste hopper 1. A screw feeder 5 is provided at the bottom of the waste hopper 1 so that the waste 2 in the waste hopper 1 is cut out.

  The gasification furnace 3 is formed in a cylindrical vertical shape, and the conveyance outlet side of the screw feeder 5 is connected to the upper part, so that the waste 2 cut out from the waste hopper 1 is put into the gasification furnace 3. ing. At the bottom of the gasification furnace 3, an air or oxygen gas supply port 23 that is an oxidant gas and a water vapor gas supply port 24 that is a water gasifying agent are provided. The gas supply ports 23 and 24 are connected to an oxidant supply means 7 for supplying air or oxygen as an oxidant gas and a water vapor supply means 8 for supplying water vapor, respectively. Further, at the bottom of the gasification furnace 3, a discharger 27 for extracting combustion residues including ash and incombustibles in the furnace is provided. The discharger 27 is configured such that the extraction amount can be adjusted. As for the combustion residue extracted by the discharger 27, the ash is sent to the disposal step 12 through the separator 9, and is subjected to, for example, a melting process or a landfill process. The incombustible pellets 39 extracted together with the ash by the discharger 27 are separated from the ash and other incombustible substances (metals, etc.) by the separator 9 and then returned to the adsorption tower and recycled.

  On the other hand, a cylindrical vertical adsorption tower 31 is provided at the top of the gasification furnace 3. The adsorption tower 31 is filled with incombustible pellets 39 that are incombustible solid particles. As the incombustible pellet 39, in this embodiment, a granular porous material (for example, a particle size of 25 to 30 mm) containing alumina is used.

  Pyrolysis gas and water gas (hereinafter collectively referred to as product gas) generated in the gasification furnace 3 are sent to the combustion boiler 13 via the adsorption tower 31. The combustion boiler 13 has a general configuration in which combustion air 14 is supplied from supply means (not shown) and the generated gas is burned to generate steam 11. The steam 11 generated in the combustion boiler 13 is supplied to the steam turbine 17 and used for power generation, and the combustion exhaust gas 16 is sent to the exhaust process 15 so as to be attracted by an induction fan (not shown) and exhausted from the chimney. It has become. Further, a control device (not shown) is provided, and at least the amount of waste transported by the screw feeder 5, the amount of oxidant gas supplied by the oxidant supply means 7, the amount of water vapor supplied by the water vapor supply means 8, and the discharger 27. It is configured so that the amount of extraction can be controlled.

  A basic operation of the waste gasification apparatus including the moving bed type gasification furnace 3 configured as described above will be described. First, the waste 2 cut out from the waste hopper 1 is put into the gasification furnace 3. The waste 2 thrown into the furnace is filled from the bottom into the cylindrical furnace to form a packed bed. The input amount of the waste 2 is adjusted so that a space is formed at least at the top of the gasification furnace 3.

  Thus, the oxidant gas is supplied from the gas supply port 23 to the gasification furnace 3 filled with the waste 2 and the waste 2 is ignited. Here, the waste 2 is ignited by blowing high-temperature air at 400 ° C. with a hot air generator, for example. The supply amount of the oxidant gas is adjusted, the waste is partially burned to form a combustion zone, and the waste in the upper layer is thermally decomposed by the combustion heat of this combustion zone. Here, the thickness of the combustion zone is determined according to the supply amount of the oxidant gas per hour, and the height position is determined according to the extraction rate of the residue at the furnace bottom. Therefore, by controlling the oxidant supply amount of the oxidant supply means 7 and the extraction amount of the discharger 27 within a predetermined range, the partial combustion and thermal decomposition of the waste can be in a steady state.

In such a steady state, a combustion zone is formed at a stable position in the furnace, a pyrolysis zone is formed at the top, and a waste drying zone is formed at the top. In the pyrolysis zone, the waste is pyrolyzed to produce combustible pyrolysis gas and carbon (char). The char generated here flows down to the combustion zone and burns, and the temperature of the combustion zone becomes 1000 ° C., for example. Further, a part of the char generated in the thermal decomposition zone reacts with water vapor supplied from the gas supply port 24 to generate CO and H ₂ . The combustion residue generated by the combustion flows down from the combustion zone. The oxidant gas and water vapor supplied from the gas supply ports 23 and 24 at the furnace bottom are preheated when rising through the gap between the combustion residues at the furnace bottom, and the combustion residue is cooled by the oxidant gas and water vapor. . The supply amounts of the oxidant gas and water vapor are adjusted so that most of the generated char becomes combustion gas and water gas.

  The high-temperature product gas, which is a mixture of the pyrolysis gas and water gas generated in this way, rises in the gasification furnace 3 through the gaps between the wastes in the drying zone and is reduced by drying the wastes. Warm (eg, about 200 ° C.). At the same time, some of the fly ash in the product gas is trapped in the waste layer. The product gas that has passed through the drying zone is supplied to the combustion boiler 13 through an adsorption tower 31 provided at the top of the gasification furnace 3. When the product gas passes through the adsorption tower 31, the tar content contained in the product gas and the suspended solids accompanying the product gas are adsorbed and removed by the non-combustible pellets 39.

  Next, the structure of the adsorption tower 31 which is the characteristic part of this embodiment is demonstrated. As shown in FIG. 1, the adsorption tower 31 is formed in a cylindrical vertical type having a diameter smaller than that of the gasification furnace 3. A non-combustible pellet 39 is introduced into the adsorption tower 31 through a double damper 41 to form a packed layer of the non-combustible pellet 39. An opening 29 is formed in the top wall of the container 21 of the gasification furnace 3, and the adsorption tower 31 and the gasification furnace 3 are communicated with each other through the opening 29. Inside the adsorption tower 31, a shaft 35 supported rotatably at the top of the adsorption tower 31 is provided. A disk 37 is connected to the lower end of the shaft 35. The shaft 35 is rotated by a motor 33 provided at the top of the adsorption tower 31.

  The disk 37 is horizontally disposed below the opening 29, that is, at a position facing the opening 29 in the gasification furnace 3. The interval between the disk 37 and the opening 29 is set to be larger than the particle size of the incombustible pellet 39, and the incombustible pellet 39 falls through the opening 29 into the gasification furnace 3 from the edge of the disk 37. The diameter of the disk 37 is formed to be larger than the diameter of the opening 29 so that the noncombustible pellets 39 flowing down from the opening 29 can form an angle of repose in which the disk 37 stably rests on the disk 37. Further, on the upper surface of the disk 37, a protruding blade of a ridge that has an angle with respect to the radial direction of the disk 37 is formed. Thereby, when the disk 37 rotates, the incombustible pellet 39 mounted on the disk 37 is cut out by the cutting blade.

  Operation | movement of the adsorption tower of this embodiment comprised in this way is demonstrated. First, the product gas in the gasification furnace 3 flows into the adsorption tower 31 through the opening 29 as shown by the arrow 38, and flows through the layer of incombustible pellets 39 to remove the tar content in the product gas. As indicated by the arrow 40, the gas is discharged from the upper part of the adsorption tower 31. When the motor 33 is driven to rotate the disk 37, the non-combustible pellets 39 that have been stationary on the disk 37 are cut out in the radial direction of the disk 37 by the cutting blades and put into the gasification furnace 3. The non-combustible pellets 39 charged into the gasification furnace 3 are mixed with the waste 2 charged from the screw feeder 5. A packed bed is formed together with the waste 2. Here, it is preferable that the mixing ratio with the non-combustible pellets 39 is constant (for example, 7: 3).

  The tar content of the incombustible pellets 39 charged into the gasification furnace 3 is thermally decomposed in the thermal decomposition zone, or reacts with water vapor to generate a product gas containing hydrogen and carbon monoxide. At this time, since the alumina component constituting the incombustible pellet 39 acts as a catalyst, decomposition of substances such as tar is promoted. The noncombustible pellets that have passed through the combustion zone are dispersed in the combustion residue, and the porosity of the layer of the combustion residue is made uniform. As a result, the uneven flow of the oxidant gas and water vapor in the combustion residue is improved and a stable combustion zone is formed, so that the gasification efficiency by thermal decomposition and the like is improved.

  As described above, according to the present embodiment, in the adsorption tower 31, the tar content in the product gas and the suspended substances accompanying the product gas can be adsorbed and removed by the non-combustible pellets 39. Therefore, it is possible to prevent occurrence of clogging of the gas pipe line or combustion failure caused by the tar content in the generated gas. Further, by introducing the non-combustible pellets 39 adsorbing tar content into the gasification furnace 3, the adsorbed tar content can be decomposed into hydrogen, carbon monoxide, etc., and can be effectively gasified, and not decomposed. The tar content can be used for combustion in the combustion zone.

  Further, the non-combustible pellets 39 that have passed through the combustion zone are dispersed in the combustion residue at the bottom of the furnace, improving the bias in the flow of oxidant gas due to solids such as non-combustibles, forming a stable combustion zone, Gasification efficiency by decomposition or the like can be improved, and if non-combustible pellets are separated by a separator, they can be recycled by returning them to the adsorption tower again. Moreover, since the surface area can be increased by forming the incombustible pellets 39 from a porous body, the amount of adsorption of tar can be increased. In addition, by configuring the incombustible pellets 39 with a substance containing alumina, alumina acts as a catalyst in the thermal decomposition zone, and the decomposition of substances such as tar can be promoted.

  Further, the discharger 27 only needs to be able to adjust the extraction amount. For example, when a screw feeder having a general configuration or a disk provided on the furnace bottom rotates, the combustion residue on the furnace bottom is cut out in the radial direction. A rotary extractor can be used.

  The motor 33 can be driven in synchronization with the screw feeder 5. According to this, the mixing ratio of waste and incombustible pellets can be controlled within a certain range. Alternatively, the amount of waste input may be detected, and the motor 33 may be driven accordingly. Furthermore, in this embodiment, although the example which supplies the gas produced | generated by the gasification furnace 3 to a combustion boiler was mentioned and demonstrated, it is not restricted to this, Various apparatuses using produced | generated gas, for example, a gas turbine, gas It can also be supplied to engines.

It is sectional drawing of the vertical moving bed type gasifier of one Embodiment to which this invention is applied. It is a whole lineblock diagram of one embodiment of a waste gasification device to which the present invention is applied.

Explanation of symbols

3 Gasification furnace 5 Screw feeder 21 Container 23, 24 Gas supply port 27 Discharge machine 29 Opening 31 Adsorption tower 33 Motor 35 Shaft 37 Disc 39 Non-combustible pellet

Claims (5)

Waste is put into a gasification furnace to form a packed bed, an oxidant gas is supplied from below the packed bed to partially burn the waste, and the waste heat gasifies the waste. , In a waste gasification method for continuously treating waste by discharging combustion residues from below the packed bed,
A waste gasification method in which product gas is purified by passing through an adsorption tower filled with incombustible particles, and the incombustible particles in the adsorption tower are put into the gasification furnace for treatment.   The waste gasification method according to claim 1, wherein the noncombustible particles are a porous material containing alumina. A container, a waste inlet formed in an upper part of the container, an oxidant gas supply port formed in a lower part of the container, and a combustion residue outlet formed in a lower part of the container. In a waste gasifier equipped with a gasification furnace for discharging product gas from the upper part of the container,
An adsorption tower filled with non-combustible particles for allowing the product gas to flow therethrough, and an input means for extracting the non-combustible particles in the adsorption tower and introducing them into the upper part of the container, Waste gasifier.   The adsorption tower is provided connected to an opening formed in the top wall of the container, and the charging means is a disk disposed in the container so as to face the opening, and a rotation driving means for rotating the disk. The disk is formed larger than the opening, and a protrusion having a predetermined angle with respect to the radial direction of the disk is formed on the upper surface. The waste gasifier described in 1.   The waste gasifier according to claim 3 or 4, wherein the non-combustible particles are porous bodies containing alumina.

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