JPS614794A - Method for recovering heat of coke oven gas - Google Patents

Abstract

PURPOSE:To recover effectively heat without causing any troubles due to materials formed by heat decomposition, by effecting heat exchange between coke oven gas cooled by water and/or ammonia liquor and a low-temperature heat fluid. CONSTITUTION:Coke oven gas heated to 600-800 deg.C is introduced through the lower part of a cooling tower 20 into the lower, and vaporized together with water and/or ammonia as coolant sprayed from an inlet pipe 21 within the tower 20 to thereby cool it. At the same time, a recycling soln. is sprayed from the upper part of the tower 20 on the gas by means of a pump 22 to cool the gas to 500 deg.C or below at which new materials are hardly formed by heat decomposition. The gas is then introduced from the upper part of a heat recovery device 30 thereinto, and heat exchange between said gas and a low-temperature heat fluid within a tubular heat exchanger 31 is conducted. At the same time, a tar recycling soln. is sprayed by means of a pump 33 to scrub condensed tar formed on the heat exchanger 31.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for recovering heat retained in coke oven gas generated when coke is produced by carbonizing coal.

[Prior art]

Conventionally, when producing coke by carbonizing coal in a coke oven, the by-products generated from the coke oven together with coal are first cooled, and then the gas is converted into coke oven gas (hereinafter referred to as CO).
The tar gas oil and ammonia are recovered as by-products, and the gas liquid is detoxified by wastewater treatment equipment and then disposed of. These gas treatment processes can be roughly divided into four: a generated gas cooling and discharging process, an NH removal process, a light oil recovery process, and a desulfurization process.

As an example, FIG. 2 shows a system diagram of the above COG gas treatment process.

In FIG. 2, COG generated from the coke oven 1 is sprayed with ammonium water (gas liquid) in the riser pipe section 2, cooled from about 600 to 800°C to 85 to 90°C, and then cooled to the gas coolers 3, 4. Cool to 30-65°C in Step 6 and remove tar and ammonium water. Tar and ammonium water are separated by a decanter 7 and a separation tank 8, the tar is collected in a tar tank 9, and the ammonium water is evaporated as paper by a stripper 10, an aeration tank 11, a coagulation tank 12, and a sand filter. 16. After treatment with activated carbon filter 14 etc., discard as treated water.

Gas coolers include a combination type of an indirect type cooler 3 (heat exchange using seawater or industrial water) and a direct type cooler 4 (ammonium water spraying type) and an indirect type.

The gas after the cooler is subjected to a naphthalene scrubber 5 to remove naphthalene, and a discharger 15 suctions and pressurizes the gas before sending it to the next process. Naphthalene is recovered from the cleaning liquid of the naphthalene scrubber 5 through a naphthalene removal tower 17. Also, discharge machine 1
Before and after 5, remove tar mist by mechanical method or electrostatic precipitator 16
etc. to remove it.

In the above conventional COG treatment process, ・60
Tar is included in COG at a temperature of 0 to 800°C, and tar exhibits various behaviors during the cooling process.
As mentioned above, cooling is performed simply by spraying ammonium water, and the heat of the generated gas is not utilized very much.

In the case of partial heat recovery, the generated gas is directly recovered from the heat source from the high-temperature region, so the accumulation of thermal decomposition products, tar, etc. generated in the process becomes a problem.

There has long been a desire to solve these problems and effectively utilize the heat retained by COG.

[Summary of the invention] The present invention cools gas at 600 to 800°C generated from a coke oven to a temperature at which thermal decomposition products are difficult to generate, and in the process, removes tar that condenses and generates gas. The purpose is to exchange retained heat with low-temperature fluid and recover heat.

The present invention solves the problems of conventional COG heat recovery, and includes a step of cooling coke oven gas to 100 to 500 °C with ammonium water and/or water in order to recover the heat retained in the gas, and a step of cooling the coke oven gas with ammonium water and/or water. This is a method for recovering heat from coke oven gas, which includes a heat recovery step in which heat retained in gas from the process is exchanged with a low-temperature thermal fluid.

According to the method of the present invention, the heat retained in COG can be exchanged with a low-temperature fluid such as water or Florinol, and recovered as a high-temperature fluid, making it possible to significantly improve energy efficiency compared to conventional gas processing methods. It is.

[Embodiments of the invention]

The present invention will be described based on FIG. 1, which is an embodiment example.

FIG. 1 is an explanatory diagram of the method of the present invention.

The present invention involves a cooling process in which components in the gas are cooled down to a temperature at which thermal decomposition products are difficult to generate, and a heat recovery process in which the heat retained in the generated gas is efficiently exchanged with a low-temperature fluid. configured.

In the cooling process, COG is introduced from the lower part of the cooling tower 20, and ammonium water or water (
Industrial water) is sprayed in a mist and evaporatively cooled in the cooling tower 20. On the other hand, to collect condensed products, tar is used as the circulating fluid, and the circulating fluid is sprayed from the top of the tower by the pump 22 to generate thermal decomposition products. Cool to a temperature of 500°C or less, where it is difficult for substances to be generated. The circulating fluid uses tar as a replenishing fluid to prevent the accumulation of condensed products, and excess fluid is discharged outside the system and the condensed products are collected separately. It is also possible to recover heat from the circulating fluid or surplus fluid.

Next, the heat recovery device 60 in the heat recovery process is a tube type heat exchanger that supplies low temperature fluid to the tube 31 side and C to the shell 32 side.
OG is introduced from the upper part of the heat recovery device 60, and cooling gas is discharged from the lower part. On the other hand, tar or the like is circulated and sprayed onto the surface of the tube 31 by a pump 36, and the tar condensed on the tube 61 due to the heat exchange of the gas is quickly washed away and the heat exchange characteristics are maintained. In order to increase the cleaning effect of the tar circulation liquid, it is preferable to arrange the tubes 31 in a diagonal manner.

Further, the circulating tar is replenished with tar and the like for viscosity adjustment, while excess tar in the circulating tar is discharged and treated separately.

Heat may be recovered from these circulating tars and surplus tars.

The low-temperature fluid may be selected depending on the level of the heat source where the heat is to be used, but it is preferable to use water if the temperature is 250°C or higher, and use Florinol or the like if the temperature is 250°C or lower.

With such a configuration, the exhaust gas from the heat recovery process is cooled, while the heat retained in the COG is exchanged with the low temperature fluid and sent to the heat utilization destination as a high temperature fluid, where it is effectively utilized and heat is recovered.

〔Effect of the invention〕

According to the coke oven gas heat recovery method of the present invention, COG
This makes it possible to exchange the retained heat of the coke with the low-temperature fluid without the trouble caused by pyrolysis products, and the recovered heat can be used effectively, making a significant contribution to energy savings in the coke manufacturing process. .

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention, and FIG. 2 is a diagram of a conventional coke oven gas treatment process. In the figure, S...steam, CW...cooling water, M...
Motor, P... Pump, 1... Coke oven, 3, 4
．． 6...Gas cooler, 7...Decanter-18...
Separation tank, 10...S) IJ tube 115...Discharge machine, 20...Cooling tower, 21...Inlet conduit, 22...
- Circulation pump, 30... Heat recovery device, 61... Tube, 62... Shell, 63... Pump. Agent Patent Attorney Sanro Kimura Figure 1

Claims (1)

[Claims] Coke oven gas in ammonium water and/or water at 100-500%
1. A method for recovering heat from coke oven gas, comprising a step of cooling the gas to a temperature of 0.degree. C., and a heat recovery step of exchanging heat retained in the gas from the cooling step with a low-temperature thermal fluid.