JP2002089825A - Indirect water cooling method for waste gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the serious problems with the prior art that since water is sprayed directly into waste gas, the water is mixed with dust in the waste gas and dioxin and is hence contaminated, which mixture must be then processed, and further since the water dispersed in the waste gas is vaporized into waster vapor, which vapor then increases the quantity of the waste gas, which gas is in turn dissipated into the atmosphere, and further since hydrochloric acid and sulfuric acid are liable to be produced by directly dissipating water into the waste gas, causing corrosion of installations such as pipes and plates in later processes. SOLUTION: In the present invention, waste gas exhausted fro a stoker furnace, a fluidized bed furnace, a direct melting furnace, a gasifying melting furnace, an arc furnace, a plasma furnace, and a shaft furnace are indirectly cooled using a medium such as water, a cooling solution or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling of high-temperature exhaust gas discharged from a furnace for incinerating or melting general waste and industrial waste.

[0002]

2. Description of the Related Art Conventionally, a so-called cooling tower has been used. For example, water is directly sprayed on combustion gas or exhaust gas flowing from a boiler or an economizer outlet, and the cooling temperature is reduced by utilizing the latent heat of evaporation of water. FIG. 1 shows an example of the structure of a cooling tower for spraying water directly on combustion gas or exhaust gas.

[0003]

In this prior art,
Since water is directly sprayed into the exhaust gas, the water is contaminated by mixing with dust and dioxin in the exhaust gas, and there is a serious problem that this sewage must be treated.

[0004] Further, since water sprinkled in high-temperature exhaust gas is vaporized, there is a serious problem that the amount of exhaust gas increases as steam and is released to the atmosphere.

[0005] Further, direct spraying of water into the exhaust gas easily generates hydrochloric acid, sulfuric acid, and the like, and has a serious problem in that the facilities such as pipes and plates in the subsequent process are corroded. Therefore, there has been a serious defect that the exhaust gas temperature must be kept at or above 150 ° C. to prevent the drainage and dew condensation of hydrochloric acid and the like.

[0006]

According to the present invention, combustion gas and exhaust gas discharged from a stoker furnace, a fluidized bed furnace, a direct melting furnace, a gasification melting furnace, an arc furnace, a plasma furnace, a shaft furnace, and the like are converted into water, The problem is solved by indirect cooling using a medium such as a cooling solution or a cooling gas.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 2, the present invention uses a double pipe to flow exhaust gas into an inner pipe and flow exhaust medium by flowing a medium such as cooling water, a cooling liquid, or a cooling gas into an outer pipe. Let cool.

【The invention's effect】

As a result, the exhaust gas is rapidly cooled to suppress the resynthesis of dioxin.

[0009] In the conventional method, chlorine and the like are generated.
Although it was quenched from 0 ° C. to 200 ° C., in the present invention, since water is not directly sprayed on the exhaust gas, generation of corrosive substances such as hydrochloric acid and sulfuric acid in the combustion gas or the exhaust gas is reduced, and the temperature is reduced to 150 ° C. or less. Combustion gas and exhaust gas can be cooled. As shown in Table 1, dioxin in exhaust gas can be significantly reduced by cooling the present invention to 150 ° C. or lower.

According to the present invention, since the cooling water is not brought into contact with the exhaust gas, the necessity of sewage treatment is eliminated.

[0010] Further, by circulating the cooling water, the cost can be reduced. Table 2 shows a comparison of the running cost of water use between the conventional method and waste water treatment per 1 ton of general waste and the present invention.

[0011]

[Brief description of the drawings]

FIG. 1 is a structural example of a conventional technique

FIG. 2 is a diagram showing a method of performing indirect cooling.

FIG. 3 shows an embodiment of a multi-stage cooling method.

[Explanation of symbols]

 Reference Signs List 1 Indirect cooling device 2 Flow of circulating water to cooling tower, etc. 3 Inner pipe 4 Outer pipe 5 Flow of circulating water from cooling tower, etc. 6 Hopper 7 Exhaust gas flow

Claims (5)

[Claims] An incinerator for incinerating general waste and industrial waste, an incinerator such as a fluidized bed furnace and an electric furnace, a direct melting furnace for melting general waste and industrial waste, a gasification melting furnace, an arc furnace, and the like. Water is directly inserted into the combustion gas or exhaust gas discharged from a so-called waste treatment furnace such as a plasma furnace or a shaft furnace, and the pipe through which the combustion gas or exhaust gas passes is sprayed from outside without spraying and cooling. Alternatively, indirect gas cooling using a cooling liquid or a cooling gas. 2. A multi-stage gas cooling method comprising arranging two or more cooling devices according to claim 1 and controlling the exhaust gas temperature on the outlet side of each of the cooling devices. 3. A combined cooling method in which the process according to claim 1 and 2 is combined with a conventional process of directly spraying water on a gas to cool the gas. 4. A steel furnace process such as a blast furnace, a converter, a coke oven, a heating furnace, and a sintering furnace, a cement manufacturing process such as a rotary kiln, and a cooling of combustion gas and exhaust gas in a food processing process. A method using the cooling method according to claim 1 and claim 2 and claim 3. 5. The method of claim 1, 2, 3 or 4.
A method for cooling a combustion gas or an exhaust gas to a temperature of 150 ° C. or less by the process according to claim 4.