JP2008039257A - Fluidized bed type gasification melting furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the sand layer temperature of a gasification furnace at the temperature suitable for gasification, with a simple constitution for reducing an increase in electric power consumption and facility cost, in a fluidized bed type gasification melting furnace. <P>SOLUTION: The sand layer temperature can be maintained at the proper temperature, by igniting a combustion improver blown in by a sand layer burner 4, while restraining an increase in the electric power consumption and the facility cost, by arranging the sand layer burner 4 being a simple device of only blowing the combustion improver in a sand layer 2 of the gasification furnace 1. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fluidized bed gasification melting furnace that incinerates waste such as municipal waste.

  Gasification melting furnaces that incinerate waste such as municipal waste include a fluidized bed type having a fluidized bed composed of a sand layer at the bottom of the gasification furnace. In such a fluidized bed type gasification melting furnace, the input waste is partially combusted in the fluidized bed, and the temperature of the sand layer that is the fluidized medium of the fluidized bed is maintained at about 500 to 600 ° C. by the combustion heat, Waste heat is pyrolyzed and gasified by the heat retained in the sand layer. However, when a large amount of waste such as soot is put in, the latent heat of the water held by the waste increases, so the heat loss due to the drying of the waste in the sand layer increases, and the gasification furnace The balance of heat balance will be lost and it will be difficult to maintain the sand layer temperature.

On the other hand, in order to maintain the sand layer at an appropriate temperature even when the amount of waste containing a lot of moisture increases, oxygen enrichment of fluidized air (partial combustion air) that causes the sand layer to flow (for example, patent documents) 1) and the installation of a dehydrator as a waste pretreatment facility.
JP 2002-327183 A (paragraph 0023, FIG. 1)

Of the above-described conventional techniques, when oxygen enrichment of fluidized air is performed, the partial combustion rate is usually increased by blowing oxygen-rich air having an O ₂ concentration of 25 to 30% into the sand layer, and the gas is supplied to the gasifier. The sand layer temperature is maintained by increasing the heat input. However, in this case, the amount of heat of the pyrolysis gas decreases due to an increase in the partial combustion rate in the gasification furnace, making it difficult to maintain the temperature in the subsequent melting furnace, and the amount of auxiliary combustor consumption in the melting furnace increases. Moreover, the oxygen generator used for oxygen enrichment normally reduces the nitrogen concentration in the air by an adsorption method, and the power consumption required for this is very large, and the equipment cost is also large.

  On the other hand, when a dehydrator is installed as a waste pretreatment facility, what is to be treated is waste, the composition is not constant, and contamination of foreign matters is unavoidable. There is a problem with stable operation. In order to avoid this, installation of a bypass line and the like are complicated, and as in the case of oxygen enrichment, power consumption and equipment cost are increased.

  In addition, if oxygen enrichment of fluidized air and installation of a dehydrator are not implemented or if it is difficult to maintain the temperature of the sand layer, the heat loss due to the latent heat of waste in the sand layer is suppressed. Therefore, measures are taken in terms of operation, such as reducing the amount of waste input. For this reason, the processing capacity of the gasification furnace is reduced, and accordingly, the total heat input to the melting furnace is reduced, so that the consumption of auxiliary combustible material in the melting furnace is further increased.

  An object of the present invention is to enable a sand bed temperature of a gasification furnace to be maintained at a temperature suitable for gasification with a simple configuration with little increase in power consumption and equipment cost in a fluidized bed gasification melting furnace. is there.

  In order to solve the above-mentioned problems, the present invention provides a sand bed burner for blowing a combustion aid into a sand bed forming a fluid bed at the bottom of the gasification furnace in a fluid bed type gasification melting furnace for incinerating waste. installed.

  In other words, by installing a sand layer burner, which is a simple device that simply blows the auxiliary material into the sand layer of the gasifier, the auxiliary material injected with the sand layer burner ignites and suppresses an increase in power consumption and equipment costs. The temperature can be maintained at an appropriate temperature.

  In the above configuration, when the sand layer burner has a nozzle that sprays the auxiliary combustion material and a sleeve that covers the outer periphery thereof, the flowing air that flows the sand layer is transferred between the sleeve and the nozzle of the sand layer burner. By blowing the air through the sand layer, it is possible to prevent the ignition failure of the auxiliary material in the sand layer due to the lack of oxygen in the gasification furnace.

  Further, if the fluidized air is preheated appropriately before being blown into the sand layer, the temperature of the sand layer is decreased by blowing the fluidized air compared to the case of using room temperature air while preventing the nozzle from burning. As well as reducing the consumption of auxiliary combustion materials. In addition, since the ignition point of the auxiliary combustion material is about 500 ° C., the stability of ignition can be improved by blowing preheated high-temperature air.

  Further, if a flame detector for detecting the ignition of the auxiliary combustion material is attached to the sand layer burner, the blowing of the auxiliary combustion material is stopped when the ignition of the auxiliary combustion material is not detected, thereby improving the safety of the gasifier. Can be increased.

  As described above, the fluidized bed gasification melting furnace of the present invention is provided with the sand layer burner for blowing the auxiliary material into the sand layer of the gasification furnace, so that even if the amount of waste containing a lot of water increases, The sand layer can be maintained at an appropriate temperature. Moreover, the sand layer burner has a simple structure and can be used by connecting to a pipe branched from a conventional facility, so that an increase in power consumption and an increase in facility cost are very small. In addition, the conventional method does not increase the partial combustion rate of the gasification furnace due to oxygen enrichment of fluidized air, and the total heat input to the melting furnace does not decrease due to the reduction of waste input. There will be no increase in the consumption of auxiliary combustion materials. Rather, since the partial combustion rate is reduced and the amount of waste input can be increased, it is possible to reduce the consumption of auxiliary combustion materials in the melting furnace even when waste containing a lot of moisture is input. . Therefore, even if the amount of the auxiliary combustion material consumed by the sand layer burner is taken into consideration, the total amount of auxiliary combustion material consumption hardly increases. Also, among the auxiliary combustors introduced from the sand layer burner, it does not contribute to the warming of the sand layer due to combustion, and the volatilized and gasified fuel burns in the melting furnace, thus contributing to the heating of the entire gasification melting furnace. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. This fluidized bed gasification melting furnace includes a gasification furnace 1 shown in FIG. 1 and a melting furnace (not shown) connected to the gasification furnace 1. The gasification furnace 1 has a fluidized bed composed of a sand layer 2 at the bottom of the furnace, and pyrolyzes and gasifies waste introduced into the furnace 1 by the heat retained in the sand layer 2 (about 500 ° C.). In the center of the furnace 1 in the height direction, a waste inlet 10 and an overhead burner 11 for heating the sand layer 2 at start-up are provided. An air nozzle 3 and a sand layer burner 4 for blowing a combustion aid into the sand layer 2 are provided so as to penetrate the furnace wall 1a. An air preheater 7 that preheats the flowing air moderately (about 100 to 300 ° C.) by heat exchange with the exhaust gas discharged from the melting furnace in the air passage 6 for sending the flowing air to the gasification furnace 1; A branch path 6 a that branches downstream from the preheater 7 and is connected to the sand layer burner 4 is provided.

  As shown in FIG. 2, the sand layer burner 4 includes a nozzle 5 that sprays a combustion-supporting material on the sand layer 2 and a sleeve 8 that covers the outer periphery of the nozzle 5. The nozzle 5 mixes the auxiliary combustion material (kerosene or LPG is desirable) supplied to the receiving part 5a on the base end side and compressed air as the spray medium and sprays it from the tip. Then, the auxiliary combustion material sprayed on the sand layer 2 ignites in the sand layer 2 at about 500 ° C. to maintain or increase the sand layer temperature. The spraying of the auxiliary combustion material is automatically performed when a decrease in the sand layer temperature is detected. Further, when the temperature of the sand layer is extremely lowered, there is a danger due to the non-ignition of the auxiliary material. Therefore, a safety circuit is provided such as automatically stopping the spraying of the auxiliary material when the sand layer temperature is 470 ° C. Further, as a safety measure, a flame detector 9 is provided for detecting the ignition of the auxiliary combustion material by looking into the furnace 1 from the through hole 1b formed in the furnace wall 1a, and spraying of the auxiliary combustion material is performed when the ignition of the auxiliary combustion material is not detected. I try to stop. As this flame detector 9, an ultraviolet photoelectric tube (Ultravision), a cadmium sulfide photoelectric tube cell flame detector, a flame rod type flame detector, or the like can be used.

A branch path 6a of the air flow path for flowing air 6 is connected to an air receiving section 8a formed on the base end side of the sleeve 8, and the flowing air supplied from the branch path 6a to the receiving section 8a is supplied to the sleeve 8. And the nozzle 5 are blown into the sand layer 2 so that the auxiliary combustion material sprayed from the nozzle 5 is mixed with the fluid air and easily ignited. This is because the gasification furnace 1 is basically supplied with only 20 to 30% of the theoretical air quantity necessary for combustion of waste, and the oxygen concentration in the furnace 1 is close to 0%. at some reason, it is directly sprayed to improve combustion in the sand layer 2, to improve combustion is not ignited by the lack of oxygen, because there may become to burn in the freeboard is thermally decomposed to volatile or CO, H _2, etc. is there. In addition, it is necessary to set the blowing speed of the flowing air into the sand layer 2 to be somewhat large in order to prevent the gap between the sleeve 8 and the nozzle 5 from being blocked by sand and to promote the mixing of the flowing air and the auxiliary combustion material. It is desirable that the speed be 45 m / sec or more.

  The installation position of the sand layer burner 4 is desirably a height of 500 mm from the upper surface of the air diffusion nozzle 3. By installing the sand layer burner 4 in the vicinity of the upper surface of the air diffuser nozzle 3, the auxiliary combustion material sprayed from the nozzle 5 is mixed with the fluid air blown from the air diffuser nozzle 3 and becomes easier to ignite. .

  This fluidized bed gasification and melting furnace has the above-described configuration, and the sand layer temperature is maintained at an appropriate temperature while suppressing an increase in power consumption and equipment cost by installing the sand layer burner 4 in the gasification furnace 1. Can do.

  Further, a part of the moderately preheated flowing air is passed between the nozzle 5 of the sand layer burner 4 and the sleeve 8 covering the outer periphery thereof, so that the auxiliary combustion in the sand layer due to oxygen shortage in the gasification furnace 1 is performed. Material ignition failure can be prevented. Moreover, it is not necessary to use the nozzle cooling air different from the flowing air, and the total amount of flowing air required for gasification is constant. Further, since the temperature drop of the sand layer 2 due to nozzle cooling is small, the amount of air and auxiliary material consumed by the sand layer burner 4 is small. In addition, the ignition of the auxiliary combustion material can be stabilized by introducing preheated air.

Schematic of the principal part of the fluidized bed type gasification melting furnace of an embodiment Enlarged cross-sectional view of the sand layer burner installation position of the gasification melting furnace of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gasification furnace 1a Furnace wall 1b Through-hole 2 Sand layer 3 Aeration nozzle 4 Sand layer burner 5 Nozzle 5a Reception part 6 Air supply path 6a Branch 7 Air preheater 8 Sleeve 8a Reception part 9 Flame detector

Claims (4)

  In a fluidized bed gasification and melting furnace that incinerates waste, a fluidized bed gasification and melting characterized by the installation of a sand layer burner that blows auxiliary material into the sand layer that forms the fluidized bed at the bottom of the gasification furnace. Furnace.   The sand layer burner has a nozzle that sprays the auxiliary combustion material and a sleeve that covers an outer periphery of the nozzle, and fluid air that flows the sand layer is blown into the sand layer through the sleeve and the nozzle of the sand layer burner. The fluidized bed type gasification melting furnace according to claim 1, wherein   The fluidized bed gasification melting furnace according to claim 2, wherein the fluidized air is preheated before being blown into the sand layer.   The fluidized bed gasification melting furnace according to any one of claims 1 to 3, wherein a flame detector for detecting the ignition of the auxiliary combustion material is attached to the sand layer burner.

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