JPH0445729B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is aimed at solving the problem of the generation of clinker in the hearth, which is particularly likely to occur at the end of operation, when tires, plastic waste oil, industrial waste, etc. are carbonized into gas. The present invention relates to a combustion method in a carbonization gasification furnace to prevent combustible gas and increase the amount of combustible gas.

(Prior art) Conventionally, mechanical stoker furnaces have been widely used in waste incinerators, but in these furnaces, the gasification of waste and the combustion of generated gas are performed almost simultaneously, without distinction. and combustion becomes incomplete, leaving soot and unburned substances in the exhaust gas,
It was polluting the air and becoming a source of secondary pollution. As a measure to prevent this, combustion devices that distinguish between gasification and combustion have recently been developed.

As mentioned above, a carbonization gasification furnace is used to gasify waste. In a carbonization gasification furnace, approximately 30% of the theoretical air amount is introduced, and the oil content in the waste is removed.
Wood, plastic, etc. are thermally decomposed and wrinkled and thermally decomposed to generate flammable gas, which is then carbonized and partially produces carbon monoxide, which is extracted as carbonized gas, and the residual carbon and ash in the furnace are in a red-hot state. keep it. Thermal energy of the generated carbonized gas is recovered using a boiler or combustion furnace.

Particularly in the batch carbonization method, combustion and shutdown occur frequently, but if air supply is continued in the same way as during normal operation before the end of operation, even if approximately 30% of the theoretical amount of air is introduced. In addition, the amount of oxygen becomes excessive with respect to the residual carbon content mentioned above, and the temperature rises too much, the combustion becomes intense and the ash itself melts and becomes clinker, and furthermore, if there is glass etc. in the waste, it is easy to melt. If the substance is present, it will melt and form clinker within the ash layer, blocking the air flow path, making it difficult to remove the ash layer, and in some cases requiring heavy labor such as crushing the ash layer with a hammer. To avoid this, if the amount of air is excessively restricted, the furnace temperature will drop and clinker generation can be prevented, but since the amount of air is reduced, the carbonization gas cannot be transferred to the next stage combustion furnace. The disadvantage is that heat recovery is also insufficient. Such an operation can also occur at the end of combustion in a carbonization gasifier in a continuous carbonization system.

Japanese Patent Publication No. 50-6749 was published as a prior art technology that distinguishes between a carbonization gasification furnace and a combustion furnace when burning waste, and controls and recirculates the combustion exhaust gas to the carbonization gasification furnace to suppress the temperature rise in the carbonization gasification furnace. There is an incinerator described in the publication, in which the supply of air is stopped to the carbonization gasifier, which is called the first combustion chamber, and only circulating gas is used.
The amount is adjusted to create a steamed state, and the material is gasified by thermal decomposition while preventing the generation of black smoke that occurs when the temperature of the first combustion chamber increases when the combustion material is introduced.

(Problem to be solved by the invention) However, since the wastes inputted are of various types such as rubber, plastics, and other industrial wastes, the oxygen content remaining in the combustion exhaust gas becomes unstable. In the prior art mentioned above, since the supply of air to the first combustion chamber is stopped, it is difficult to maintain an appropriate oxygen concentration even if the flow rate of combustion exhaust gas is controlled, and it is difficult to prevent clinker generation and prevent steaming. There are problems such as no consideration being given to the effective use of combustible materials that still remain in the furnace at the end of the process and can be gasified.

(Means for Solving the Problems) In view of the above, the present invention gasifies the residual carbon that remains in a red-hot state before the end of the operation of the carbonization gasifier at a low temperature, and facilitates the transfer of the generated carbonization gas. The present invention provides a carbonization gasification furnace combustion method for cooling and heat recovery of ash in a red-hot state and further preventing the generation of clinker in the ash layer. In a combustion apparatus equipped with a gas combustion furnace and an exhaust gas circulation pipe that branches from the combustion furnace flue and connects to the carbonization gasification furnace, an appropriate amount of air is introduced into the carbonization gasification furnace during normal operation. This is a carbonization gasifier combustion method in which carbonization gas is generated, the introduced air is restricted before the end of operation, and the mixture is mixed with the exhaust gas from the exhaust gas circulation pipe and introduced into the carbonization gasification furnace.

(Example) The figure is a flow sheet in one embodiment of the present invention, and as shown in FIG. 3 is provided in the upper part, a fixed retort 4 is provided in the lower part, a side wall ignition device 5 is attached, a gas outlet 6 is connected to the upper part of the side wall, and a mixed gas inlet of air and circulating exhaust gas is provided in the lower part. 7
is open. Separate inlet pipes may be installed for air and circulating exhaust gas.

The combustion furnace 8 is arranged horizontally, for example, and is connected to the carbonization gasification furnace 1 through a gas pipe 9, and is surrounded by a fan 10.
A secondary air inlet 11 is opened, and a boiler water pipe 12 for waste heat recovery is installed inside the furnace. ing.

On the inlet side of the exhaust gas purifier 14, an exhaust gas circulation pipe 17 branched from the flue and having a gas flow rate control valve 16 is provided, and an air introduction pipe 19 having a flow rate control valve 18 is connected to the pipe line 17. Then, a mixture of air and exhaust gas is introduced into the carbonization gasification furnace 1 from the inlet 7 via the blower 20. 21 is a filter.

In the combustion apparatus having the above configuration, the waste 22 charged into the carbonization gasifier is ignited by the ignition device 5, and the air is regulated to about 30% of the theoretical air amount by the flow rate control valve 18. It is supplied by the fan 20 for normal operation. Combustible materials form a preheating layer, reduced layer, oxidized layer, and ash layer, and generate carbonized gas.

The generated carbonized gas then enters the combustion furnace 8, is ignited by the ignition burner 23, and combustion continues with the supply of secondary air from the air inlet 11, and the thermal energy is transferred to the waste heat recovery boiler 12 and the heat recovery device. Heat is recovered by 13.

The input waste 22 decreases as it is gasified, the residual carbon becomes red hot, the amount of gas generated decreases, and the operation is nearing completion. Here, the air control valve 18 is operated to limit the amount of air to below the amount of air during normal operation, and the circulating exhaust gas is guided through the pipe 17. Therefore, in the carbonization gasification furnace 1, the amount of oxygen decreases and the temperature becomes low, and gas is generated while preventing clinker generation, and the calorific value of the generated gas, red residual carbon, and red hot ash is increased by the added circulating exhaust gas. It is transferred to the combustion furnace 8 and burned. The circulating exhaust gas, which is not involved in combustion, acts exclusively as a heat transfer medium for the heat recovered from the red-hot residual carbon and red-hot ash to the waste heat recovery boiler and waste heat recovery device.

(Effects) The present invention provides a combustion apparatus equipped with a carbonization gasification furnace, a carbonization gas combustion furnace, and an exhaust gas circulation path that branches from the combustion furnace flue and connects to the carbonization gasification furnace, with an appropriate amount of air during normal operation. is introduced into the carbonization gasification furnace, and before the operation is completed, the amount of air introduced is limited, circulating exhaust gas is introduced to maintain the temperature inside the carbonization gasification furnace at a low temperature, and flammable gas is generated from the residual carbon. This carbonization gasifier combustion method is characterized by preventing the generation of clinker, so as the combustibles are gasified in the carbonization gasifier, the amount of combustibles decreases at the end of operation, resulting in less gas generation. Even if red-hot carbon and red-hot pressure remain, a more limited amount of air is introduced than during normal operation, and circulating exhaust gas is introduced, so flammable gas is not generated from red-hot carbon. and the combustible gas can be transported by circulating exhaust gas and reach the combustion furnace,
Thermal energy is further increased by combustion, and the combustible materials in the input waste can be used without waste.

In addition, the red-hot carbon remaining in the carbonization gasifier is combusted by the more limited amount of air and the circulating exhaust gas, which has a lower oxygen content than the outside air, so the excessive combustion is at a low temperature, which reduces the generation of clinker. It has a preventive effect.

[Brief explanation of drawings]

The figure is a flow sheet in one embodiment of the present invention. 1... Carbonization gasification furnace, 3... Waste injector, 4
... fixed retort, 5 ... ignition device, 7 ... mixed gas inlet, 8 ... combustion furnace, 11 ... secondary air inlet, 12 ... boiler water pipe for waste heat recovery, 13 ... heat recovery device, 14...Exhaust gas purifier, 15...Chimney, 16...Gas flow rate control valve, 17...Exhaust gas circulation pipe, 19...Air introduction pipe.

Claims (1)

[Claims] 1. In a combustion apparatus equipped with a carbonization gasification furnace, a carbonization gas combustion furnace, and an exhaust gas circulation pipe branching from the combustion furnace flue and connecting to the carbonization gasification furnace, during normal operation, an appropriate amount of air is converted to carbonization gasification. Carbonization gasifier combustion characterized by introducing carbonization gas into the furnace to generate carbonization gas, limiting the amount of introduced air before the end of operation, mixing with exhaust gas from the exhaust gas circulation path, and introducing it into the carbonization gasification furnace. Method.