JP2005029728A - Gasification apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasifying furnace for gasifying roughly crushed waste to produce a gas free from tar. <P>SOLUTION: The gasifying furnace of the gasification apparatus is composed of a vertical cylindrical gasifying furnace 13 having a gas discharging port 71 for discharging produced gas at the top of the furnace, a fire grate placed at the bottom part of the gasifying furnace 13, a raw material supplying port 69 opened on the sidewall of the gasifying furnace 13 to supply the raw material to the fire grate, a feeding port 63 to supply a gasifying agent containing oxygen to the fire grate, a discharging port 67 to discharge incombustible material from the fire grate and a nozzle 65 positioned on the sidewall of the gasifying furnace 13 and supplying the oxygen-containing gasifying agent in tangential direction to form a jet flow layer. The apparatus can gasify the roughly crushed wastes and discharge produced gas free from tar. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gasification apparatus that efficiently gasifies coarsely pulverized waste, particularly organic waste.

  In general, as a method of recycling organic waste such as waste plastic, car shredder dust, biomass waste, etc., in order to improve the recovery efficiency, from the thermal recycling that recovers and uses the heat generated during the incineration process In addition, organic waste is led to a gasification furnace to be gasified, and conversion to chemical recycling is attempted in which the generated gas is used as a raw material for manufacturing industrial materials and fuels.

  Gasification furnaces that gasify organic waste and the like as solid raw materials are classified into types such as a fixed bed, a fluidized bed, and a spouted bed according to the reaction mode of the raw materials. The fixed bed gasification furnace deposits the coarsely pulverized raw material on the fixed bed and heats it to gasify, and the fluidized bed gasification furnace supplies the raw material to the fluidized fluidized bed by blowing air into the fluidized medium. Is heated and gasified by heating. The spouted bed gasification furnace gasifies at a high temperature by forming a spouted bed by entraining the finely pulverized raw material with a gasifying agent containing oxygen swirling in the furnace. Each of these gasification furnaces has advantages and disadvantages, and an optimum type is selected depending on the raw material properties and other conditions.

  By the way, when the raw material is pyrolyzed and gasified, tar of a volatile component is generated. When the tar is discharged from the furnace together with the pyrolysis gas, it adheres to the inner wall of the downstream pipe and becomes oily, which becomes a cause of blocking the inside of the pipe. In particular, since the tar production rate increases as the pyrolysis temperature of the gasification furnace decreases, a large amount of tar is generated in the gasification furnace of the fixed bed or fluidized bed.

  Therefore, as a method for removing such tar, a product gas containing tar discharged from the gasification furnace is used in a high temperature (for example, 1000 ° C. or higher) atmosphere by a reforming furnace provided downstream of the gasification furnace. A method of decomposing and removing is known. As an example of using this reforming furnace, a method in which combustible gas, char and tar discharged from a fluidized bed gasification furnace are led to a reforming furnace disposed downstream and gasified (reformed) at a high temperature. Is disclosed (see Patent Document 1).

  However, according to this method, since gasification and reforming are performed in separate furnaces, there is a problem that the apparatus becomes complicated and large.

On the other hand, according to the spouted bed gasification furnace, since the raw material is gasified at a high temperature of 1000 ° C. or higher, all the tar is decomposed, and therefore, the raw material is converted into H ₂ and CO without generating tar in one furnace. It can be converted into a gas-based synthesis gas.

JP-A-11-166185

  However, according to the above-mentioned spouted bed gasification furnace, a pulverization step is required to pulverize the raw material into fine particles of several millimeters or less. In particular, a large amount of energy including a drying process is required for atomization of biomass having a large amount of fiber. On the other hand, high-cost materials such as plastic, rubber, and urethane employ freeze pulverization. In addition, shredder dust containing metal scraps, etc., requires sorting processes such as magnetic sorting, wind sorting, and sieve classification, which increases processing costs. May occur. In other words, the spouted bed gasification method is effective for simplifying the apparatus and suppressing tar, but there is a problem that the pulverization of waste, particularly organic waste, is costly and difficult to apply. Conventionally, no consideration is given to these points in waste gasification furnaces.

  An object of the present invention is to provide a gasification furnace capable of gasifying coarsely pulverized waste and discharging a generated gas containing no tar.

  In order to solve the above problems, the present invention provides a vertical cylindrical gasification furnace having a gas discharge port for discharging a generated gas at the top, a grate provided at the bottom of the gasification furnace, and a gasification furnace A raw material supply port for supplying a raw material to the grate unit provided on the side wall, a supply port for supplying a gasifying agent containing oxygen to the grate unit, a discharge port for discharging incombustibles from the grate unit, and a gasification furnace And a nozzle for supplying a gasifying agent containing oxygen in a tangential direction to form a spouted layer.

  According to such a configuration, first, when the coarsely pulverized waste is supplied into the gasification furnace, it falls on the grate and accumulates, and the gasifying agent is blown from the lower supply port. Part starts burning. The pyrolysis gas containing tar generated by pyrolyzing the waste heated by the combustion is swirled in the swirling flow of the gasifying agent and swirled up in the furnace, and is heated to a high temperature (for example, 1000 ° C. or higher). ) And is rapidly gasified and reformed. That is, by incorporating a fixed bed and a spouted bed in one gasification furnace, waste is gasified by a low temperature fixed bed even in a coarsely pulverized state, and then the tar content is gasified by the high temperature spouted bed. It becomes. In addition, since the incombustible material on a grate is discharged | emitted from the discharge port formed in a grate part, it is not necessary to sort waste as a pre-processing.

  In this case, it is desirable that the grate is a plurality of movable stokers. According to this, the combustion and gasification of the waste are activated by the vibration of the grate, and even if a large amount of incombustibles are contained, it can be discharged continuously and stably.

  Moreover, it is desirable to provide a control means for controlling the amount of the gasifying agent supplied to the nozzle so that the temperature of at least the upper part of the gasification furnace is maintained in the range of 1000 ° C. to 1300 ° C. In this case, the upper part of the furnace can be maintained at an optimum temperature for tar decomposition by adjusting the amount of the gasifying agent supplied to the furnace according to the furnace temperature using a flow rate adjusting valve or the like. Here, for example, the nozzles are arranged in two stages in the height direction of the gasification furnace, the furnace temperature in the upper part of the gasification furnace is 1000 ° C. to 1300 ° C., and the furnace temperature in the lower part of the gasification furnace is 850 ° C. Control means for controlling the amount of the gasifying agent to be supplied to the nozzle may be provided so as to be held in a range of from 900 ° C. to 900 ° C., respectively. That is, by maintaining the temperature of the grate portion in a predetermined temperature range, the waste can be burned and gasified without melting. As described above, if the nozzles are arranged in a plurality of stages, a temperature distribution can be formed in the height direction of the gasification furnace, and waste can be efficiently gasified. In addition, when controlling the temperature of a grate part, you may make it control the quantity of the gasifying agent injected into a grate part by the said control means.

  According to the present invention, coarsely pulverized waste can be gasified, and the product gas containing no tar can be discharged.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a waste recycling system to which the present invention is applied. In this embodiment, the organic waste is used as the raw material waste, but the present invention is not limited to this.

  As shown in the figure, the waste recycling system includes a gasification step 1 for gasifying organic waste (hereinafter, appropriately referred to as waste), and a gas purification step for purifying the generated gas generated in the gasification step. 3 and a gas utilization process 5 utilizing purified gas. The gasification step 1 includes a pulverizer 7, a raw material hopper 9, a screw feeder 11, a gasification furnace 13, a ventilator 15, and an oxygen production device 17. In the horizontal crusher 7, a hopper 19 is connected to one end, and a discharge port at the other end is connected to a supply port of the raw material hopper 9. In the raw material hopper 9, the lower portion of the cylindrical container is constricted in an inverted conical shape, and the central discharge port is connected to the supply port at one end of the screw feeder 11. The screw feeder 11 is configured to horizontally transfer the waste supplied from the supply port to the discharge port at the other end when the screw connected to the driving device rotates. The discharge port of the screw feeder 11 is connected to a substantially middle side wall portion of the gasification furnace 13 having a vertical cylindrical shape. A stoker 21 described later is formed at the bottom of the gasification furnace 13. On the side wall of the gasification furnace 13, above the connection port of the screw feeder 11, two stages of nozzles 23 and 25 serving as gasification agent introduction ports are arranged vertically. The nozzles 23 and 25 are connected to a gas introduction pipe 31 formed by connecting an air introduction pipe 27 and an oxygen introduction pipe 29, respectively. The air introduction pipe 27 is connected to the ventilator 15 via an air flow rate adjustment valve 33. On the other hand, the oxygen introduction pipe 29 is connected to the oxygen production apparatus 17 via the oxygen flow rate adjustment valve 35. A nozzle 37 is connected to the lower space of the stoker 21, and the nozzle 37 is connected to the ventilator 15 through an air introduction pipe 39 provided with an air flow valve 41.

  The gas produced in the gasification step 1 is usually a mixed gas mainly composed of hydrogen and carbon monoxide, but depending on the composition of the waste, chlorine, sulfur, heavy metals, etc. may be included. There is. For this reason, it is necessary to purify the product gas in the gas purification step 3 and remove them.

  The gas purification step 3 in this embodiment includes a temperature reducer 45, a mixer 47, a bag filter 53, an induction blower 57, and a gas holder 59. The product gas discharged from the gasification furnace 13 is introduced into the temperature reducer 45 through the pipe 43, cooled here, and then guided to the mixer 47. A slaked lime hopper 49 and an activated carbon hopper 51 are connected to the mixer 47 from the upstream side, and the product gas introduced into the mixer 47 is subjected to desalting, desulfurization treatment, etc. by blowing slaked lime and activated carbon. The The gas discharged from the mixer 47 is introduced into the bag filter 53 and removed, and then introduced into the gas holder 57 by the induction fan 55 and stored as purified gas.

  Examples of the gas utilization process 5 include a gas engine utilization process 59 that uses purified gas as gas engine fuel, and a liquid fuel producer 61 that regenerates liquid fuel.

  Next, a gasification furnace to which the present invention is applied will be described in detail. FIG. 2 is a configuration diagram illustrating an example of the gasification furnace in FIG. 1. As shown in the figure, the gasification furnace 13 includes a container 14, a stalker 21 formed at the bottom of the container 14, a drive cylinder 22 provided in the lower space 20, and a fire that introduces air into the lower space 20. It comprises a lattice air inlet 63, a discharge port 67 for discharging non-combustible materials, a supply port 69 for supplying waste, and a nozzle 65 for supplying a gasifying agent.

  The cylindrical container 14 has a gas discharge port 71 formed at the center of the top constricted in a conical shape. The supply port 69 formed in the substantially middle side wall of the container 14 is connected to the discharge port of the screw feeder 11 so that the coarsely pulverized waste stored in the raw material hopper 9 is supplied into the container 14. It has become. The stalker 21 is formed in a staircase shape with a plurality of grate slanted, and each grate is moved back and forth, for example, when the drive cylinder 22 swings in the direction of the arrow. In addition, a gap is provided between each grate, and the combustion air supplied from the grate air inlet 63 passes through the stalker 21 and is blown into the container 14, and the waste accumulated in the stalker 21 is removed. It is designed to burn. The discharge port 67 is formed to project from the container 14 so as to extend the stoker 21 downward, and a rotary valve 73 is connected to the tip of the discharge port 67. The nozzle 65 is disposed above the supply port 69 and is preferably disposed in the tangential direction of the furnace wall so that the gasifying agent swirls and flows in the container 14. In addition, for example, it is preferable that a plurality of nozzles 65 are arranged to face each other in the circumferential direction of the container 14, and two or more stages are arranged in the height direction of the container 14. Moreover, although screw feeder 11 was applied in this embodiment as a method of supplying waste continuously to container 14, it is not restricted to this, For example, a rotary feeder etc. may be used.

Next, operation | movement is demonstrated about the gasification furnace 13 of this invention. A gasifying agent is injected from a nozzle 65 into the container 14 of the gasification furnace 13, and swirls along the inner wall of the container 13 as indicated by an arrow. For this reason, for example, when the waste pulverized to have a particle size of about several centimeters is dispensed by the screw feeder 11 and supplied into the container 14, the particle size of the coarsely pulverized waste is relatively small. The fine powder is entrained in the swirling flow and becomes a vigorously mixed state, that is, a spouted bed, and is immediately gasified at a high temperature of, for example, 1000 ° C. or higher. On the other hand, the coarse powder having a relatively large particle size falls without being accompanied by the swirling flow and accumulates on the stoker 21 at the bottom. The coarse powder deposited on the stalker 21 is slowly heated, for example, at about 850 ° C. by the combustion air supplied from the lower part of the grate, partly burns and gasification (pyrolysis) proceeds. Although this gas contains volatile tar, it is taken into the swirling flow of the gasifying agent and swirls up in the furnace, and when it reaches the hot spouted bed, it is gasified and reformed in a few seconds. Further, the waste that has been reduced in diameter by burning or gasifying the waste on the stoker 21 is taken into the swirling flow as particles, swirling up in the furnace, and gasified in the spouted bed. Further, when combustion occurs on the stoker 21, high-temperature carbon dioxide is generated. Similarly, when taken into the spouted bed, as shown in Equation 1, it reacts with the carbon content present in the spouted bed, and a gasifying agent. It works as effectively. That is, even if coarsely pulverized waste is supplied, it is possible to suppress the discharge of tar and fine particles from the gasification furnace 13 by combining a fixed bed such as a stoker and a spouted bed.
CO ₂ + C → 2CO (Equation 1)
Here, as the gasifying agent supplied into the container 14 from the nozzle 65, a gas containing at least oxygen is applied, and for example, oxygen, oxygen-enriched air, and air can be used. For example, by connecting an air flow rate adjustment valve 33 and an oxygen flow rate adjustment valve 35 to each nozzle and controlling the opening amount of each valve based on the temperature detection value in the container 14, the supply amount of gasification agent, the oxygen concentration Etc. can be adjusted. Thereby, if the nozzles 65 are installed in a plurality of stages in the height direction of the container 14, regions where the partial pressure and temperature of the gasifying agent are different in the height direction in the container 14 are formed. The furnace environment is suitable for each stage of gasification and gas reforming, and gasification efficiency can be improved. Note that water vapor may be added from the nozzle 65 in addition to the gasifying agent. According to this, the reforming efficiency of the product gas can be improved.

  In the above case, the temperature distribution is controlled so that the upper part of the container 14 forming the spouted bed is maintained at a temperature range of about 1000 ° C. to about 1300 ° C. where gasification such as tar is optimally performed. preferable. Further, the lower part of the container 14 is preferably controlled so as to be maintained at a temperature range of 850 ° C. to 900 ° C. According to this, incombustibles deposited on the stoker 21 can be efficiently gasified without melting them.

  In addition, the combustion air supplied from the grate air inlet 63 is blown into the stoker 21 from the gap of the grate, but this combustion air is used to prevent the incombustible material on the stoker 21 from being melted. The flow rate is adjusted by the flow rate valve 41. That is, the opening amount of the air flow valve 41 is controlled based on the detected temperature value of the stoker 21 part. Thereby, the incombustible material generated by burning the waste moves downward, for example, on a grate that moves back and forth, and is discharged from the discharge port 67 through the rotary valve 73.

  The stalker 21 continuously discharges non-combustible materials in a dry manner, and exhibits an excellent improvement effect particularly when waste contains a large amount of non-combustible materials such as ash and metal scraps. Here, the structure of the stalker 21 is not limited to the staircase-like stalker 21 shown in the present embodiment, but may be a moving stalker that moves the grate horizontally.

  Next, another embodiment of the gasification furnace 13 will be described with reference to FIG. 3 differs from FIG. 2 in that a fixed (non-movable) grate 83 is applied in place of the stalker 21 of FIG. In addition, the same code | symbol is attached | subjected to the part same as what was shown in FIG. 2, and description is abbreviate | omitted.

  In the gasification furnace 16, a grate 83 is disposed horizontally at the bottom of the container 81, and not only combustion air but also non-combustible materials such as ash and metal scraps in the wastes slip through the grate 83 naturally. A gap that falls is formed. The incombustible material that has passed through the gap is discharged through the rotary valve 73 from a discharge port formed constricted in the conical shape of the lower space 20. This type of grate 83 is applied when the waste contains a small amount of ash or non-combustible material such as woody biomass, and can reduce the cost of the apparatus. In other words, the bottom of the container 81 depends on the type of waste, but if the waste is deposited to form a fixed layer and burned or gasified, the bottom of the container 81 has a function of discharging incombustibles. Such a structure may be used.

  Further, in the gasification furnace 18 shown in FIG. 4, the gasifying agent introduction in which the nozzles 65 in the gasification furnace 16 of FIG. 3 are arranged in two stages in the height direction of the container 85 and connected to the nozzles 87 and 89. The difference is that gasifying agent flow rate adjusting valves 91 and 93 are respectively provided in the pipes. According to this, the device cost is higher than that of the one-stage arrangement type, but the controllability with respect to the temperature distribution in the height direction of the container 85 is improved.

As described above, according to the present embodiment, by combining the spouted bed and the fixed bed (including the stoker) in one gasification furnace, the product gas containing no tar is roughly removed from the coarsely pulverized organic waste. Can be discharged. This eliminates the need for fine pulverization and separation of metals as pre-treatment of waste, and tar is completely gasified in the gasification furnace, so that the downstream piping facilities are contaminated with tar. No clogging or clogging occurs. In addition, since pyrolysis gasification and reformed gasification of waste can be processed in one furnace, the equipment is downsized, the gasification efficiency is increased, and the amount of gasifying agent used is reduced, which is economical. .
Moreover, although the example which applies the dry method was demonstrated as the gas purification process 3 in this embodiment, it is not restricted to this, For example, you may apply a wet method. That is, according to the dry method, the operation and the apparatus are simple, a removal rate of nearly 100% can be obtained, and it is possible to cope with a wide variation in the concentration of the gas to be processed. Although the treatment cost is relatively low, it is difficult to obtain a removal rate close to 100%, and additional wastewater treatment is required, resulting in an increase in equipment size. Therefore, it is preferable to select an appropriate gas purification method according to the processing scale of the gasifier and the concentration of harmful components.

  The purified gas obtained from the gasification step 1 and the gas purification step 3 of this embodiment is used for in-house power generation as a gas engine fuel, or produces alcohols such as methanol and ethanol, dimethyl ether, various olefins and the like as chemical raw materials. Suitable for doing. In particular, a fuel produced by the FT method using a catalyst such as iron or cobalt has little sulfur content, and is desirable for both the internal combustion engine and the environment. Furthermore, since a linear hydrocarbon is a main component, the diesel fraction has a high cetane number, and is highly valuable as a diesel fuel and the blend material. In addition, a chemical recycling system having extremely excellent environmental properties can be constructed by combining the highly efficient waste gasification method according to this embodiment and the FT synthesis method.

It is a block diagram of the waste recycling system to which this invention is applied. It is a block diagram which shows an example of the gasification furnace in FIG. It is a block diagram of the gasification furnace formed by applying a fixed grate instead of the stoker of the gasification furnace in FIG. It is a block diagram of the gasification furnace in which the nozzle of the gasification furnace in FIG. 3 is arrange | positioned 2 steps | paragraphs at the height direction of a container.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification process 3 Gas purification process 5 Gas utilization process 13, 16, 18 Gasification furnace 14, 81, 85 Vessel 21 Stoker 63 Grate air inlet 65, 87, 89 Nozzle 67 Outlet 69 Supply port 71 Gas exhaust Exit

Claims (5)

A vertical cylindrical gasification furnace having a gas discharge port for discharging generated gas at the top, a grate provided at the bottom of the gasification furnace, and a raw material provided at the grate side wall of the gasification furnace A raw material supply port, a supply port for supplying a gasifying agent containing oxygen to the grate portion, a discharge port for discharging incombustibles from the grate portion, and a tangential direction provided on the gasifier side wall And a nozzle for supplying a gasifying agent containing oxygen to form a spouted layer. The gasifier according to claim 1, wherein the grate is a stalker composed of a plurality of movable grate. 2. A control means for controlling an amount of the gasifying agent supplied to the nozzle so as to maintain a temperature of at least an upper part of the gasification furnace in a range of 1000 ° C. to 1300 ° C. The gasifier according to 1 or 2. The nozzles are arranged in two stages in the height direction of the gasification furnace, the furnace temperature at the upper part of the gasification furnace is 1000 ° C. to 1300 ° C., and the furnace temperature at the lower part of the gasification furnace is 850 ° C. to 900 ° C. 3. The gasifier according to claim 1, further comprising a control unit configured to control the amount of the gasifying agent supplied to the nozzle so as to be held in a range of ° C. 3. The said control means controls the quantity of the said gasifying agent supplied to the said supply port so that the temperature of the said grate part may not reach the melting point of the said incombustible substance, The Claim 3 or 4 characterized by the above-mentioned. The gasifier described.

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