JP2006071215A - Thermal decomposition gasification melting system and its temperature raising method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste gasification melting system capable of completing temperature raising of the system in a short time and reducing the use of fuel excluding wastes. <P>SOLUTION: This thermal decomposition gasification melting system includes a fluidized bed-type thermal decomposition gasification furnace 3 for thermally decomposing wastes, a swivel melting furnace 6 connected with the thermal decomposition gasification furnace 3 through a pyrolysis gas flow channel 5, and burning the pyrolysis gas and char produced in the thermal decomposition gasification furnace 3 to obtain a high-temperature field to melt ash in the char, and an auxiliary fuel supply pipe 21 for supplying auxiliary fuel to the pyrolysis gas flow channel 5. The pyrolysis gas flow channel 5 can be cooled by switching a water-cooling mode and an air-cooling mode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pyrolysis gasification furnace that pyrolyzes general waste and industrial waste, etc., and a melting furnace that burns pyrolysis gas and char generated in the gasification furnace and obtains a high temperature field to melt the ash in the char The present invention relates to a pyrolysis gasification melting system and a temperature raising method thereof.

  Pyrolysis gasification and melting system for general waste, industrial waste, etc., is generated by supplying garbage and waste as fuel to a fluidized bed gasification furnace and pyrolyzing and gasifying it in a shortage of air. And the char which has unburned carbon and ash as a main component is burned with a melting furnace, a high temperature field is obtained and the ash in char is made into molten slag. During this process, waste is reduced in volume, and dioxins are completely decomposed and detoxified at high temperatures.

  A gasification furnace start burner and a melting furnace start burner are installed in the gasification furnace and the melting furnace, respectively, and when the system is started, the temperature is raised using a start burner using kerosene or the like as fuel. Normally, the amount of air supplied to the fuel is set in advance in the start burner (generally, an air ratio of about 1.2), and the amount of fuel is increased or decreased by the output regulator to raise the furnace temperature.

  The characteristic of the waste gasification and melting system is that the temperature of the gasification furnace and melting furnace is maintained by the energy of the waste. At startup, it is necessary to raise the temperature of the gasification furnace and melting furnace using auxiliary fuel such as kerosene. There is. This is because, unless the temperature of the gasification furnace is raised to about 600 ° C., the waste is not stably pyrolyzed and gasified. This is because it is necessary to raise the temperature to about (° C.) or higher.

  Here, when the temperature of the gasification furnace is increased, combustion gas and fluidized air for the gasification furnace starting burner are supplied to the gasification furnace, and it is burned by reacting with fuel from the gasification furnace starting burner. A large amount of combustion exhaust gas (usually 600 to 900 ° C.) is discharged from the furnace. This large amount of combustion exhaust gas flows directly into the melting furnace directly connected to the gasification furnace through the pyrolysis gas flow path. On the other hand, in the melting furnace, combustion air is supplied to the melting furnace starting burner, and there is a problem that the temperature of the furnace is difficult to rise in combination with the combustion exhaust gas fed from the gasification furnace. The following methods are considered as means for solving these problems, but none of them are effective or have operational problems.

(1) Bypassing the gasification furnace combustion exhaust gas so that it does not flow into the melting furnace at start-up, the temperature of the two furnaces is increased independently. Can be set to 1300 ° C. or higher. However, the temperature of the gasification furnace combustion exhaust gas at the time of start-up and the temperature of the pyrolysis gas at the time of waste gasification are as high as 600 to 900 ° C., and the pyrolysis gas contains corrosive hydrogen chloride generated from the waste. Therefore, there are no valves or dampers that can be used to switch the gas flow path, and it cannot be used in reality.

(2) Method of raising the temperature by enriching the combustion air of the melting furnace starting burner with oxygen: a high oxygen burner and oxygen cylinder, or an oxygen enrichment device is required, resulting in high costs.

(3) Method of using oxygen in gasification furnace combustion exhaust gas for melting furnace melting: Gasification furnace is supplied with a large amount of air such as fluidized air in addition to burner combustion air. The residual oxygen concentration is as high as 10%. If oxygen in the gasification furnace combustion exhaust gas is used as combustion oxygen for the melting furnace, the air ratio of the melting furnace start burner can be lowered to less than 1 to reduce the total gas amount, without increasing the amount of kerosene. It is possible to raise the melting furnace temperature. However, a normal burner has a preset air ratio to the fuel (air ratio of about 1.2), and in order to change the fuel amount and air amount independently, Since the air ratio setting must be changed mechanically, it is difficult to adjust and it is not possible to respond flexibly.

(4) Method of supplying fuel to the gasifier side: As disclosed in Patent Document 1, if fuel is supplied to the gasifier side, the start-up burner of the melting furnace can be abolished, and the burner air Therefore, it is easy to raise the temperature of the melting furnace. However, when fuel is supplied to the gasification furnace, the temperature of the gasification furnace needs to be as high as that of the melting furnace, and in a gasification furnace in which a refractory material having a heat resistant temperature lower than that of the melting furnace is applied, There is a problem that the degree of material damage is increased.

  Patent Document 2 discloses a technique for adjusting the amount of air in the start burner of each of the gasification furnace and the melting furnace independently of the amount of fuel in the refuse gasification and melting apparatus. However, it is expensive to install a start-up burner in the melting furnace.

JP-A-9-236220 (pages 2 to 3) JP 2001-296013 A (page 5)

  An object of the present invention is to complete the temperature rise of the system in a short time and to reduce the amount of fuel used other than garbage in view of the problems at the time of starting the conventional garbage gasification and melting system.

  The above problems include a pyrolysis gasification furnace for pyrolyzing waste, a pyrolysis gas generated in the pyrolysis gasification furnace connected to the pyrolysis gasification furnace through a pyrolysis gas flow path, and A melting furnace for burning the char to obtain a high temperature field and melting the ash in the char, and means for supplying auxiliary fuel to the pyrolysis gas channel, wherein the pyrolysis gas channel is water-cooled This is achieved by a pyrolysis gasification and melting system configured to be able to cool by switching between a system and an air cooling system.

  The type of the melting furnace is preferably a swivel type.

  According to the said structure, the starting burner of a melting furnace becomes unnecessary and the amount of combustion gas of a melting furnace can be reduced. Furthermore, by supplying auxiliary fuel to combustion exhaust gas having a high oxygen concentration discharged from a pyrolysis gasification furnace (hereinafter referred to as gasification furnace), the temperature of the exhaust gas flowing into the melting furnace can be effectively increased. It is possible to raise the temperature of the melting furnace in a short time. The exhaust gas discharged from the gasification furnace contains a large amount of oxygen, and high temperature gas can be obtained by supplying auxiliary fuel to the pyrolysis gas flow path. However, since there is a risk of the refractory material in the pyrolysis gas flow path being melted, the cooling method of the pyrolysis gas flow path is switched to the water cooling method at the start-up to prevent the refractory material from being melted. In the case of single operation of garbage, that is, pyrolysis gasification operation, the temperature of the pyrolysis gas flowing through the pyrolysis gas passage is as low as about 600 to 800 ° C. Switch to reduce heat dissipation.

  If the type of the melting furnace is a swivel type, it is possible to effectively distribute the high temperature gas to the inner wall of the melting furnace, so that in addition to the above effects, the temperature raising time of the melting furnace can be further shortened.

  According to the present invention, the startup time of the gasification and melting system can be shortened, the amount of fuel used can be reduced, and the fuel cost can be reduced. Moreover, since it is not necessary to install a burner in the melting furnace, the equipment cost can be reduced.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 is a system diagram showing a main part configuration when the present invention is applied to a pyrolysis gasification melting system for general waste. A pyrolysis gasification melting system according to the present embodiment includes a fluidized bed pyrolysis gasification furnace (hereinafter referred to as a gasification furnace) 3 provided with a supply hopper 1 and a dust supply device 2, and heat is supplied to the gasification furnace 3. A revolving melting furnace 6 connected by a cracked gas flow path 5, a revolving combustion furnace (hereinafter referred to as a melting furnace) 6, a secondary combustion chamber 7 provided for complete combustion of exhaust gas, and a secondary combustion A waste heat boiler 8 connected to the chamber 7 for the purpose of heat recovery from the exhaust gas, and an exhaust gas temperature reducing device for suppressing the resynthesis of dioxins provided connected to the waste heat boiler 8 9, connected to the exhaust gas outlet side of the exhaust gas temperature reduction device 9, connected to the dust collector 10, which is a dust collector, and connected to the exhaust gas outlet side of the dust collector 10 via the flue And a chimney 11 that emits exhaust gas to the atmosphere.

  The pyrolysis gas flow path 5 is surrounded by an air cooling / water cooling switching jacket 15, and the air cooling / water cooling switching jacket 15 includes a water supply facility 17 and an air supply facility 18 each having a flow rate adjustment valve 16. It has a structure that can be cooled by switching between a water cooling method and an air cooling method. The pyrolysis gas flow path 5 is connected to an auxiliary fuel supply pipe 21 having a fuel adjustment valve 20 interposed therebetween, and measures and outputs the temperature of the gas flowing into the melting furnace 6 at the melting furnace inlet. 12 and a control device 13 for controlling the opening degree of the fuel regulating valve 20 by using the output of the temperature measuring device 12 as an input. The auxiliary fuel supply pipe 21 is connected to an auxiliary fuel (kerosene) supply source and a compressed air source which are not shown.

  A temperature measuring device 12 is provided in each of the gasification furnace 3 and the melting furnace 6.

  Garbage is supplied from the supply hopper 1 to the gasification furnace 3 by the dust supply device 2, and the waste supplied to the gasification furnace 3 is fluidized air a supplied from the diffuser pipe 4 installed at the bottom of the gasification furnace. Fluidize with fluid medium. In this process, the waste is partially combusted and pyrolyzed to produce pyrolysis gas, char that is mainly composed of unburned carbon and ash. The generated pyrolysis gas and char are sent to the melting furnace 6 through the pyrolysis gas flow path 5, and react with the combustion air b separately supplied to the melting furnace 6 to burn. The inside of the melting furnace 6 is maintained at a temperature equal to or higher than the melting temperature of ash, and the ash in the char is melted and recovered as slag c.

FIG. 2 shows the startup operation of this system and the temperature change of each device, and the startup operation method is shown below.
a. Switching the cooling system of the pyrolysis gas flow path 5 to the water cooling system b. Supplying the fluidized air a without supplying dust to the gasification furnace 3, and starting the gasification furnace starting burner 14. c. Pyrolysis gas When the pyrolysis gas temperature in the flow path 5 exceeds 400 ° C., the fuel f (kerosene) is supplied to the pyrolysis gas flow path d and the temperature is raised until the temperature in the melting furnace 6 becomes 1300 ° C. or higher.・ Gas is supplied to the gasifier when the layer temperature of the gasifier 3 exceeds 600 ° C. f ・ Supply of fuel to the gasifier start burner 14 and the pyrolysis gas passage 5 is stopped g. After the shift to the gasification operation, the pyrolysis gas passage 5 is switched to the air cooling system when the gas temperature in the pyrolysis gas passage 5 is 800 ° C. or lower.

  In order to maintain a stable pyrolysis reaction in the pyrolysis gasifier 3, it is necessary to fluidize the gasifier fluidized bed portion in advance. For this reason, it is necessary to supply fluidized air to the gasification furnace 3 even at the start-up time when no waste is supplied. Immediately after startup, the bed temperature is low and the rate of air rise required for fluidization of the sand, which is the medium in the bed, cannot be secured, so the bed is not fluidized. Next, the gasifier starting burner 14 is started. The gasifier starting burner 14 is installed at a position and posture such that a flame collides with the layer surface so that the layer portion can be efficiently heated. As time elapses, the temperature of the gasification furnace refractory wall and the sand that is the fluidized medium rises, and the rising speed of the air increases, so that the sand begins to fluidize.

  When the temperature of the combustion exhaust gas from the gasification furnace 3 flowing through the pyrolysis gas channel 5 becomes 400 ° C. or higher, which is the temperature at which the injected kerosene can be stably burned, the kerosene as the auxiliary fuel is pyrolyzed. Sprayed onto the gas flow path 5. The spraying of kerosene employs a mechanism of atomizing with compressed air so that the spray droplets evaporate in a short time. Kerosene blown into the pyrolysis gas channel 5 reacts with oxygen (concentration of about 10%) in the combustion exhaust gas discharged from the gasification furnace 3 to form a high-temperature flame. The temperature of the exhaust gas flowing into the melting furnace 6 increases as the temperature of the gasification furnace 3 rises, and finally reaches about 1400 ° C. Since the melting furnace 6 is a swivel type, high-temperature gas flows in the vicinity of the inner wall of the melting furnace, and the inner wall of the melting furnace 6 is efficiently heated. In addition, since the pyrolysis gas flow path 5 becomes high temperature at the time of starting, it switches to the water cooling system. For this reason, even if the gas temperature of the pyrolysis gas channel 5 reaches about 1600 ° C., the wall surface of the pyrolysis gas channel 5 does not melt.

  The temperature increase to 1300 ° C. of the melting furnace 6 is completed in a short time with a high-temperature gas, and the supply of garbage to the gasification furnace 3 is started after the layer temperature of the gasification furnace 3 reaches about 600 ° C. The If the supply of waste to the gasification furnace 3 is started, the temperature of the gasification furnace 3 and the melting furnace 6 can be maintained with the energy of the waste, so that the gasification furnace start burner 14 and the pyrolysis gas flow path 5 are supplied. The fuel supply is stopped, and the operation shifts to the gasification and melting operation using only garbage. Thereafter, when the gas temperature in the pyrolysis gas channel 5 is lowered to 800 ° C. or lower, the cooling method of the pyrolysis gas channel 5 is switched from the water cooling method to the air cooling method, and the amount of heat dissipated is reduced.

It is a systematic diagram which shows the principal part structure of embodiment of this invention. It is supplementary explanatory drawing which shows the example of the operation procedure which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Supply hopper 2 Dust supply device 3 Fluidized bed type pyrolysis gasification furnace 4 Aeration pipe 5 Pyrolysis gas flow path 6 Swivel melting furnace 7 Secondary combustion chamber 8 Waste heat boiler 9 Exhaust gas temperature reduction device 10 Dust collector 11 Chimney 12 Temperature measurement device 13 Control device 14 Gasification furnace start burner 16 Flow rate adjustment valve 17 Water supply facility 18 Air supply facility 20 Fuel adjustment valve 21 Auxiliary fuel supply pipe

Claims (3)

  A pyrolysis gasification furnace for pyrolyzing waste, and the pyrolysis gasification furnace connected to the pyrolysis gasification furnace through a pyrolysis gas flow path, and burning the pyrolysis gas and char generated in the pyrolysis gasification furnace; A melting furnace that melts the ash in the char by obtaining a high temperature field, and means for supplying auxiliary fuel to the pyrolysis gas flow path, wherein the pyrolysis gas flow path includes a water cooling system and an air cooling system. Pyrolysis gasification melting system that can be cooled by switching to   The pyrolysis gasification melting system according to claim 1, wherein the melting furnace is a swirl type melting furnace. A fluidized bed type pyrolysis gasification furnace comprising a gasification furnace start burner and pyrolyzing waste, and connected to the pyrolysis gasification furnace via a pyrolysis gas flow path, Combusting the generated pyrolysis gas and char, obtaining a high temperature field and melting ash in the char, and means for supplying auxiliary fuel to the pyrolysis gas flow path, The pyrolysis gas flow path is a temperature raising method at the start of the pyrolysis gasification and melting system configured to be cooled by switching between a water cooling method and an air cooling method,
1. Procedure for switching the cooling method of the pyrolysis gas flow path to the water cooling method, supplying fluidized air without supplying waste to the gasifier, and starting the gasifier start burner,
2. Procedure for starting fuel supply to the pyrolysis gas channel when the temperature of the pyrolysis gas in the pyrolysis gas channel exceeds 400 ° C and raising the temperature until the temperature in the melting furnace reaches 1300 ° C or higher ,
3. Procedure for starting the supply of garbage to the gasifier when the bed temperature of the gasifier exceeds 600 ° C., and stopping the supply of fuel to the gasifier start burner and the pyrolysis gas flow path,
4. After shifting to normal gasification operation, the procedure is to switch the pyrolysis gas flow path to the air cooling system when the gas temperature in the pyrolysis gas flow path is 800 ° C or lower,
A temperature raising method at the start-up of the pyrolysis gasification melting system comprising:

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