JP2006131820A - Fluidized bed gasifying method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus that uses various biomass, waste plastic, coke or the like as a fuel to produce a combustible gas having a high energy and keeps a high temperature inside a furnace to produce the combustible gas at a high efficiency. <P>SOLUTION: The apparatus is a fluidized bed gasifying apparatus for using a fluidized gas to form a fluidized bed 5 inside a gasifying furnace 1 and gasify a fuel A to produce a combustible gas, wherein the apparatus comprises a boiler 12 for exchanging heat with the combustible gas produced in the gasifying furnace 1 to produce steam, and an ejector 15 for absorbing and mixing a part of the combustible gas at the outlet of the gasifying furnace 1 with the steam formed in the boiler 12 and providing the gasifying furnace 1 with the mixed gas 21 as the fluidizing gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluidized bed gasification method and apparatus for generating combustible gas with high efficiency by gasifying various biomass, waste plastic, coal, and the like as fuel.

  Conventionally, in order to reduce the volume of various wastes such as waste, heat treatment such as incineration, carbonization, and melting is performed, and steam is generated using the waste heat generated at this time to generate electricity. It has become.

On the other hand, apart from this, carbides of various organic wastes are partially oxidized or pyrolyzed by supplying air and water vapor, and the combustible gas obtained at this time is used as fuel for internal combustion engines such as gas engines and gas turbines. A method of generating electricity by using it has been proposed. In the gasification furnace that performs the thermal decomposition as described above, water vapor is supplied to cause partial combustion of the carbide and cause a water gasification reaction [C + H ₂ O = H ₂ + CO].

There exists a thing shown by patent document 1 as said gasifier. This gasification apparatus includes a gasification furnace in which dry pulverized biomass and a gasifying agent containing water vapor and oxygen (generally air) are reacted inside the gasification furnace to obtain a product gas from the biomass. A conical receiving portion having a plurality of holes formed in the peripheral surface, and a pipe portion whose upper end side is connected to the receiving portion and whose lower end side penetrates the lower portion of the gasifying furnace. A funnel having a supply pipe that feeds the fluidizing gas to the holes so that the fluidizing gas having the same composition as the gasifying agent flows from the outer surface side of the receiving portion of the funnel toward the inner surface side of the receiving portion. In this way, powder particles are prevented from remaining in the lower part of the gasifier.
JP 2004-91568 A

However, as shown in the above-mentioned Patent Document 1, in a gasification apparatus in which gasification is performed by supplying a gasification agent with water vapor and air to a gasification furnace, many inert components (N ₂ is about 72%) in the gasification agent. Therefore, there is a problem that the concentration of combustible gas in the generated combustible gas is lowered and the amount of heat is lowered.

  In addition, when supplying a gasifying agent using water vapor and air to the gasification furnace, it is necessary to increase the pressure of the water vapor and air so that the pressure required for fluidizing the fluid medium is reached. Equipment facilities are required. In addition, if steam and air are simply supplied as flow gases, the furnace temperature of the gasification furnace tends to decrease, and if the furnace temperature decreases, it takes time for the gasification reaction by steam, so that the combustible gas is added. There is a problem that it cannot be produced with high efficiency. In order to solve this productivity problem, it is necessary to keep the temperature inside the gasification furnace high by heating and supplying the steam and air to a high temperature. In addition, there is a problem in that the size of the apparatus is increased due to the necessity of equipment for heating the air and the air.

  The present invention has been made in view of the above circumstances, and can produce a combustible gas having a high calorific value using various biomass, waste plastics, coal, etc. as fuel, and maintain a high temperature in the furnace so that it is highly combustible. It is an object of the present invention to provide a fluidized bed gasification method and apparatus capable of generating a property gas.

  The present invention is a fluidized bed gasification method in which a fluidized bed is formed inside a gasification furnace with a fluidizing gas, and fuel is gasified to generate a combustible gas, the combustible gas generated in the gasification furnace, Heat is exchanged with water to generate steam, the steam is guided to an ejector, a part of the combustible gas at the gasification furnace outlet is sucked, and the mixed gas of steam and combustible gas is used as the flow gas. The present invention relates to a fluidized bed gasification method characterized by being supplied to a gasification furnace.

  In the fluidized bed gasification method, the fuel may be at least one of biomass, waste plastic, and coal.

  Moreover, in the fluidized bed gasification method, it is preferable to remove dust in the combustible gas sucked by the ejector.

  On the other hand, the present invention is a fluidized bed gasification apparatus that forms a fluidized bed inside a gasification furnace with a fluidizing gas and gasifies the fuel to generate a combustible gas, which is combustible generated in the gasification furnace. A boiler that generates steam by exchanging heat with gas, and a mixed gas in which a part of the combustible gas at the gasification furnace outlet is sucked by the steam generated by the boiler and the steam and the combustible gas are mixed. The present invention relates to a fluidized bed gasification apparatus comprising: an ejector for supplying to the gasification furnace.

  In the fluidized bed gasification apparatus, it is preferable that a ceramic filter for removing soot and dust contained in the combustible gas is provided at the gasification furnace outlet.

  According to the above means, the following operation can be obtained.

  In the fluidized bed gasification method and apparatus of the present invention, gasification is performed by supplying a gasification fuel to the gasification furnace, and the combustible gas generated inside the gasification furnace is guided to the boiler to generate steam, Steam generated in the boiler is supplied to the ejector to suck a part of the combustible gas at the gasifier outlet. Thereby, in the ejector, a mixed gas in which the steam and the combustible gas are mixed is generated, and this mixed gas is supplied to the gasifier as a flowing gas.

  When a fluidized bed is formed inside the gasification furnace by the fluidizing gas that is a mixed gas of steam and combustible gas, a combustible gas is generated by receiving an aqueous gasification reaction in an atmosphere containing high-temperature steam inside the gasification furnace. To do.

  At this time, in the ejector, the high-temperature and high-pressure steam is mixed with the combustible gas at the outlet of the high-temperature gasification furnace to become a high-temperature mixed gas. Therefore, the temperature inside the gasification furnace can be easily maintained at a high temperature, and the gasification of fuel for gasification is promoted in a high temperature atmosphere, so that combustible gas can be generated with high efficiency in a short time. .

  Furthermore, since a part of the combustible gas is circulated and supplied to the gasification furnace as a fluidizing gas, the content of inert components is significantly reduced compared to the case where air is supplied as a fluidizing gas as in the past. Thus, the amount of heat of the combustible gas is greatly increased.

  Further, the combustible gas taken out from the gasification furnace contains a tar content, but this tar content can also be gasified by circulatingly supplying a part of the combustible gas to the gasification furnace. As a result, the amount of heat of the combustible gas generated is further increased.

  According to the fluidized bed gasification method and apparatus according to claims 1 to 5 of the present invention, when a combustible gas is generated using various biomass, waste plastic, coal, or the like as a fuel, the inertness in the gasification furnace is generated. It is possible to significantly increase the calorific value of the combustible gas by reducing the ratio of the components, and to obtain an excellent effect that the combustible gas can be generated with high efficiency while maintaining the furnace temperature high.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 shows an example of an embodiment of the present invention. In the figure, 1 is a gasification furnace, and a fluid medium such as sand is mounted on the upper side of the diffuser plate 2 provided at the lower inner side of the gasification furnace 1. Furthermore, a fuel supply device 3 for supplying the gas A for gasification is provided above the diffuser plate 2. Further, a fluidizing gas is supplied to the wind box 4 below the diffuser plate 2, and the fluidized medium is fluidized by the fluidizing gas to form the fluidized bed 5. In the figure, 6 is a burner that burns by supplying fuel such as city gas, kerosene, light oil, and heavy oil into the fluidized medium when the gasification furnace 1 is started, and 7 is air as a flowing gas in the wind box 4 when starting An air supply pipe for forming a fluidized bed 5 by supplying 8. Although FIG. 1 illustrates the case where the diffuser plate 2 is provided and the flow gas is diffused into the gasification furnace 1, the diffuser may be provided with a diffuser nozzle.

In the gasification furnace 1 of FIG. 1, the gas for flow is ejected from the diffuser plate 2 upward in the gasification furnace 1, and the fuel A for gasification is injected into the gasification furnace 1 by the fuel supply device 3. The fluidized bed 5 is formed by bubbling the fluidized medium by supplying to the gas and partially burning, thereby forming a high-temperature freeboard 9 above the diffuser plate 2 inside the gasification furnace 1. In the free board 9, steam, which will be described later, is supplied to the gasification furnace 1, whereby the fuel A for gasification is gasified to generate a combustible gas such as CO or H ₂ .

  Here, as the fuel A for gasification, various biomass, waste plastic, coal and the like can be used. As the biomass, waste wood such as construction generated wood, sawmill residual material, thinned wood, damaged wood, etc. Organic waste such as waste paper, rice straw, rice husk, rapeseed, starch crops, food waste, factory effluent sludge, sewage sludge, and manure sludge including animal waste it can.

  In the above, the arrangement position of the fuel supply device that supplies the gas A for gasification to the gasification furnace 1 can be arbitrarily selected. That is, even if fuel with a low water content or fuel with a large amount of heat is supplied into or near the fluidized bed 5, partial combustion and gasification are carried out satisfactorily, but the factory effluent sludge, sewage sludge, livestock waste In particular, sludges having a high water content (e.g., about 70 to 80%) such as human waste sludge and the like are provided with a supply device 3a at the top of the gasification furnace 1 as shown by the broken line in FIG. It is preferable to supply. When the sludge is supplied from the upper part of the gasification furnace 1 in this way, the high-temperature free board 9 promotes the evaporation of the moisture of the sludge and the sludge is effectively dried. Can be easily performed.

  The high-temperature combustible gas generated in the freeboard 9 of the gasification furnace 1 is taken out by the outlet pipe 10 and guided to the ceramic filter 11 to remove the dust, and then guided to the boiler 12 and water. High-temperature and high-pressure steam is generated by heat exchange. The combustible gas cooled by heat exchange in the boiler 12 is further cooled by a cooler 13 and then supplied as fuel to an internal combustion engine such as a gas turbine GT or a gas engine GE.

  The high-temperature and high-pressure steam generated in the boiler 12 is supplied to the ejector 15 through the steam pipe 14. On the other hand, the ejector 15 is a part of the combustible gas after the dust is removed by the ceramic filter 11. Is sucked through the suction tube 16. As shown in FIG. 2, the ejector 15 includes a nozzle 18 close to the center of one end of the diffuser 17 having a tapered hole 17 a, and a suction port 19 that surrounds the outer periphery of the nozzle 18. An enclosing suction chamber 20 is provided, and when the high-temperature and high-pressure steam is ejected from the nozzle 18 toward the diffuser 17, a vacuum is formed in the suction chamber 20, thereby causing the combustible gas through the suction port 19. Is supposed to suck.

  Since the ejector 15 sucks the combustible gas by the steam as described above, the mixed gas 21 in which the steam and the combustible gas are mixed is discharged from the ejector 15. The gas is supplied to the wind box 4 as a flowing gas. 1 illustrates the case where the air supply pipe 7 and the mixed gas pipe 22 are separately provided. However, the air supply pipe 7 and the mixed gas pipe 22 are joined and connected to the wind box 4 or the air diffusion nozzle. May be.

  Although FIG. 1 illustrates the case where the ceramic filter 11 is installed in the outlet pipe 10 of the gasification furnace 1, the ceramic filter 11 may be installed in the suction pipe 16 that guides combustible gas to the ejector 15.

  Next, the operation of the illustrated example will be described.

  When the gasification furnace 1 is started, air 8 is supplied to the wind box 4 through the air supply pipe 7 and air (flowing gas) is ejected upward from the diffuser plate 2, and city gas, Fuel for starting such as kerosene, light oil and heavy oil is supplied and burned to bubbling the fluidized medium to form the fluidized bed 5, thereby raising the temperature inside the gasifier 1. When the internal temperature of the gasification furnace 1 reaches a predetermined high temperature (for example, 700 to 900 ° C.), the fuel supply device 3 supplies the fuel A for gasification, while the fuel supply by the burner 6 is reduced and stopped. Let

  The fuel A for gasification supplied into the gasification furnace 1 flows in a mixed state with a high-temperature fluidized medium in the fluidized bed 5, and part of the fuel acts to burn and maintain a high temperature. It becomes a flammable gas through the chemical reaction. At this time, the fuel A for gasification supplied to the gasification furnace 1 may be one of biomass, waste plastic, and coal, or a plurality of them may be supplied simultaneously. At this time, the sludge fuel is preferably supplied from the supply device 3a at the upper part of the gasification furnace 1.

  The combustible gas generated inside the gasification furnace 1 is led out to the outside through the outlet pipe 10 from the upper part of the free board 9, and after the dust is removed by the ceramic filter 11, it is led to the boiler 12 and heated. Water is heated by (for example, 700 to 900 ° C.) to generate high-temperature and high-pressure steam. On the other hand, the combustible gas cooled by heat exchange in the boiler 12 is further cooled by the cooler 13 and then supplied as fuel to an internal combustion engine such as the gas turbine GT or the gas engine GE.

  The high-temperature and high-pressure steam generated in the boiler 12 is supplied to the ejector 15. The ejector 15 sucks a part of the combustible gas after the dust is removed by the ceramic filter 11 through the suction pipe 16 by the action of the steam, and thereby the steam and the combustible gas are mixed from the ejector 15. A mixed gas 21 is discharged, and the mixed gas 21 is supplied to the wind box 4 as a flowing gas through a mixed gas pipe 22.

  In the boiler 12, for example, high-temperature combustible gas such as 700 to 900 ° C. and water are heat-exchanged. Therefore, high-temperature and high-pressure steam can be easily obtained. Therefore, in the ejector 15 that introduces high-pressure steam, The combustible gas at the outlet of the gasification furnace 1 can be stably sucked, and the pressure of the mixed gas 21 discharged from the ejector 15 can be maintained high. Therefore, the fluidized bed 5 can be formed by easily fluidizing the fluidized medium with the mixed gas 21. As described above, when the mixed gas 21 is supplied to the wind box 4 and the fluidized bed is stably formed, the supply of the air 8 supplied to the wind box 4 at the start-up is stopped.

  When the ejector 15 is supplied with a combustible gas containing 700 to 900 ° C. and containing dust, the ejector 15 may be worn out in a short time due to its severe conditions. Thus, the dust in the combustible gas sucked by the ejector 15 is removed by the ceramic filter 11, so that the wear of the ejector 15 can be reduced and the life of the ejector 15 can be extended. Further, when the ceramic filter 11 is provided at the outlet of the gasification furnace 1 as shown in FIG. 1, the accumulation of soot in the boiler 12 can be reduced, so that the heat exchange efficiency of the boiler 12 can be improved.

  As described above, when the fluidized bed 5 is formed by supplying the gas mixture 1 in which the steam and the combustible gas are mixed to the gasification furnace 1 as the fluidizing gas, depending on the atmosphere in which the steam exists at a high temperature inside the gasification furnace 1. The fuel A for gasification undergoes a water gasification reaction to generate a combustible gas.

  At this time, in the ejector 15, the combustible gas at the outlet of the high-temperature gasification furnace 1 is mixed with the high-temperature / high-pressure steam, and this high-temperature mixed gas 21 is circulated and supplied to the gasification furnace 1 as a flowing gas. Therefore, the inside of the gasification furnace 1 can be easily maintained at a high temperature, and thus the gasification fuel A is promoted to gasify and generates a combustible gas with high efficiency in a short time.

Further, since a part of the combustible gas is circulated and supplied to the gasification furnace 1 as a fluidizing gas, the inert component (N ₂ ) content can be significantly reduced, so that the proportion of CO and H ₂ components of the combustible gas produced is increased (becomes rich in CO and H ₂ ), and the combustible gas with a high calorific value is Can be generated.

  Furthermore, although the combustible gas taken out from the gasification furnace 1 contains tar, since a part of the combustible gas is circulated and supplied to the gasification furnace 1 as a fluidizing gas, The tar content is also gasified, whereby the concentration of the combustible component is increased, and the amount of heat of the combustible gas is further increased.

  Further, as described above, when the high temperature inside the gasification furnace 1 is maintained by the supply of the gas A for gasification, the combustion of city gas, kerosene, heavy oil, etc. by the burner 6 becomes unnecessary. Processing of waste such as waste plastic and generation of combustible gas can be achieved at low operating costs.

  The fluidized bed gasification method and apparatus of the present invention are not limited to the illustrated examples described above, and can be variously modified without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS It is a whole schematic block diagram of the fluidized-bed gasification apparatus as an example of embodiment which implements this invention. It is a cutting | disconnection side view which shows an example of an ejector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification furnace 3 Fuel supply apparatus 3a Supply apparatus 5 Fluidized bed 10 Outlet pipe 11 Ceramic filter 12 Boiler 14 Steam pipe 15 Ejector 16 Suction pipe 21 Mixed gas (flowing gas)
22 Mixed gas pipe A Gasification fuel

Claims (5)

  A fluidized bed gasification method for generating a combustible gas by forming a fluidized bed inside a gasification furnace with a fluidizing gas and gasifying the fuel, wherein the combustible gas and water generated in the gasification furnace are heated. Steam is generated by replacement, the steam is guided to an ejector, a part of the combustible gas at the gasification furnace outlet is sucked, and a mixed gas of steam and combustible gas is supplied to the gasification furnace as a flow gas A fluidized bed gasification method comprising:   The fluidized bed gasification method according to claim 1, wherein the fuel is at least one of biomass, waste plastic, and coal.   The fluidized bed gasification method according to claim 1 or 2, wherein the dust in the combustible gas sucked by the ejector is removed.   A fluidized bed gasification apparatus that generates a combustible gas by gasifying fuel by forming a fluidized bed inside a gasification furnace with a fluidizing gas, and performs heat exchange with the combustible gas generated in the gasification furnace. A steam that generates steam and a part of the combustible gas at the gasification furnace outlet by the steam generated by the boiler and a mixed gas in which the steam and the combustible gas are mixed into the gasification furnace as a flow gas. A fluidized bed gasification apparatus comprising: an ejector for feeding.   The fluidized bed gasifier according to claim 4, further comprising a ceramic filter for removing dust contained in the combustible gas at an outlet of the gasification furnace.

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