JPS6047518B2 - Method for recovering heat from crude gas generated in a coke oven - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering coke oven crude gas generated in a coke oven carbonization chamber.

Conventional coke oven crude gas of 600-8000C generated in the coke oven carbonization chamber can be reduced to 85% by brushing with ammonium water.
After being cooled to around 100°C, the gas is sucked and pressure-fed to the gas purification process, and this gas is not effectively utilized. One way to take advantage of this gas is to directly introduce it into a heat exchanger and exchange heat with it, but normal heat exchangers have the following problems and cannot be operated stably for a long period of time. That is difficult.

In other words, coke oven gas contains many high-boiling substances such as pensols and tar, as well as water and other soluble impurities, and at temperatures above 450°C, pensols and tar decompose at high temperatures and carbon is deposited on the heat transfer tube. At temperatures below 450°C, high-boiling substances such as tar condense on the heat transfer tube, and further below 100°C, water and other soluble impurities condense.

As a result, gas pipes and heat exchangers are blocked, causing so-called coking, which increases pressure loss and further reduces heat exchange efficiency.
It is difficult to operate the equipment stably for a long period of time. For this reason, several explicit recovery methods are available, such as a method in which high-boiling point oil is directly sprayed onto hot coke oven gas instead of ammonium water, and then steam is recovered by heat exchange with the high-boiling point oil; A method of generating electricity using Freon using water-saturated gas at around 85°C cooled by water brushing has been proposed.

If high boiling point oil is used, the above-mentioned impurities will be included in the gas, so it is expected that the nozzle will be clogged with coking, the pipes will be clogged with dust, and the high boiling point oil will decompose and deteriorate, so continuous operation for a long period of time is not recommended. It's difficult to say "fu".

Further, when Freon is used, there are problems such as the heat medium is special and the heat is recovered from low-temperature gas, resulting in low thermal efficiency and an increase in the size of the device.

The present invention focuses on the fact that the cause of coking is mainly carbon deposition at temperatures above 450°C and condensation of impurities at temperatures below 450°C. The object of the present invention is to provide a method for recovering heat from crude gas generated in a coke oven, which allows stable heat recovery over a long period of time without causing the above-mentioned coking. That is, the present invention is a method in which coke oven crude gas generated in a coke oven carbonization chamber is led to a spouted bed cooler for heat exchange, and then to a wet wall cooler for heat exchange.

The method of the present invention will be explained below with reference to the drawings.

FIG. 1 shows an example of a heat recovery device used in the present invention, in which two gas pipe systems 3 and 4 are provided in a riser pipe 2 connected to a carbonization chamber of a coke oven 1. One gas pipe system 3 includes a water seal valve 5, a dry main 6, a pressure control device 7,
A primary cooler 8, a pressure control device 9, and a coke oven gas blower 10 are provided in this order and connected to a gas purification device (not shown). The other gas pipe system 4 has a shutoff valve 1.
1. A new air collecting pipe 12, a spouted bed cooler 13, a wet wall cooler 1, an oil cooler 15, a flow rate control device 16, and a crude coke oven gas blower 17 are installed in this order, and connected to the dry main 6. There is. As shown in FIG. 2, the spouted bed cooler 13 has a gas inlet 18a at the lower end of an outer cylinder 18, a gas outlet 18b at the upper end, an inner cylinder 19 provided inside the outer cylinder 18, and a gas outlet 18b formed at the upper end of the outer cylinder 18. Particle splash prevention plate 20 above 19
Furthermore, a heat exchange fluid conduit 21 is provided in the gap between the outer cylinder 18 and the inner cylinder 19, and particles 22 such as heat-resistant, wear-resistant, and low-density alumina balls are inserted into the outer cylinder 18. It's on.

As shown in FIG. 3, the wet wall cooler 14 has self-byproduct tar between a gas-liquid contact tank 23 provided with a gas inlet 23a and a gas-liquid separation tank 24 provided with a gas outlet 24a. Or a flow pipe line 25 for circulating oil for heat exchange such as medium oil with high solubility.
Further, a circulation pump 26 for returning circulating oil from the gas-liquid/separation tank 24 to the gas-liquid contact tank 23 is provided.

Furthermore, the wet wall cooler 14 has a pipe line 27 for a heat exchange fluid such as water installed around the downstream pipe line 25, so that the heat of the gas is recovered using this fluid. According to the method of the present invention, the hot coke oven gas is guided to the spouted bed cooler 13 through the shutoff valve 11 and the new air collecting pipe 12.

In the spouted bed cooler 13, this gas rises inside the inner cylinder 19 from the gas inlet 18a of the outer cylinder 18, and passes through the particle ejection prevention plate 20.
The gas then flows out from the gas outlet 18b. On the other hand, particles 22 such as alumina rise inside the inner cylinder 19 as the gas rises, and then hit the particle scattering prevention plate 20 between the inner cylinder 19 and the outer cylinder.
8 (where the heat exchange fluid conduit 21 is located), the fluid descends through the gap between the pipe 21 and the heat exchange fluid, and circulates within the inner cylinder 19 again. This gas flow and the circulation of the particles 22 generate heat of the gas (600 to 8
00°C) moves from the particles 22 to the fluid in the conduit 21,
Here, the first stage of heat recovery is performed.・Spouted bed cooler 1
The coke oven gas whose heat has been recovered in step 3 and has reached a temperature of about 450'C is led to a wet wall cooler 14. In the wet wall cooler 14, the downstream pipe 2 is connected from the gas inlet 23a of the gas-liquid contact tank 23.
5 and exits from the gas outlet 24a of the gas-liquid separation tank 24. On the other hand, the circulating oil flows from the gas-liquid contact tank 23 to the downstream pipe 25.
The oil accumulates in the gas-liquid separation tank 24 while forming a liquid film inside, and is returned to the gas-liquid contact tank 23 by the action of the circulation oil pump 26. Due to the circulation of the hot coke oven gas and the circulation of the circulating oil, the heat of the hot coke oven gas is transferred from the liquid film of the circulating oil to the pipe 27.
The heat is transferred to the fluid flowing through it, where a second stage of heat recovery occurs.

The heated coke oven gas, whose heat has been recovered by the wet wall cooler 14 and has reached a temperature of about 300°C, is led to the ammonium water cooler 15 where it is sprayed with ammonium water to reduce the temperature to 70°C, and then the flow rate control device The gas enters the dry main 6 through a crude coke oven gas blower 17 for pressure compensation incorporating a gas blower 16, and is led to the gas purification equipment via a primary cooler 8 and a coke oven gas blower 10. Note that when a new gas pipeline system 4 is installed on the existing gas pipeline system 3 as in the above embodiment, both the water seal valve 5 and the cutoff valve 11 are opened and the new gas pipeline system 4 installed in the existing gas pipeline system 3 is opened. It is preferable to use the pressure control device 7 to control the pressure so that a predetermined amount of gas flows into the newly installed gas pipe system 4.

According to this method, stable pressure control and gas suction are performed. According to the present invention, however, since high-temperature coke oven gas is passed through the spouted bed cooler 13, tar and pitch in the gas are condensed on the surfaces of the particles 22.
When the particles 2 descend, they are carbonized, and further separated due to collisions between the particles 22, preventing the heat exchange fluid from adhering to the pipe line 21 and increasing its heat exchange efficiency. According to this spouted bed cooler 13, for example, 120k91c! It becomes possible to recover high-pressure steam from TG. Furthermore, the particles 22 are also self-regenerating and can be used cyclically, eliminating the need for extraction and regeneration. Note that the spouted bed cooler 14
In this case, if the cooling temperature of the gas is lowered too much, tar condensation becomes large, and particles 22 circulating in the layer tend to grow or aggregate.

Experiments have shown that tar condenses almost completely in one minute at temperatures above 450°C. Therefore, in this spouted bed cooler 13, the cooling temperature of the gas is preferably at least this temperature. Furthermore, according to the present invention, in order to guide coke oven gas whose temperature has dropped to about 450°C to the wet wall cooler 14,
Even if tar and pitch in the gas condense, they can be washed and dissolved with a large amount of circulating oil, preventing coking, improving heat transfer performance, and reducing pressure loss. For example, the wet wall cooler 14 can recover medium pressure steam of 60k91cdG. The tar contained in the crude gas generated from a coke oven begins to condense at 425°C, and at 200°C.
It was observed that the tar condensation rate was about 50% at 0C. Therefore, it is preferable that the wet wall cooler 14 circulates gas at a temperature below the above-mentioned temperature. Further, the heat recovery device used in the present invention is not limited to the above-described one; for example, as shown in FIG. New air collection pipe 3 pressure control device. 35, spouted bed cooler 36, wet wall cooler 37,
An ammonium water cooler 38, a primary cooler 39, a pressure control device 40, and a coke oven gas blower 41 are provided, and the other gas pipe system 32 is provided with a water seal valve 42, a dry main 43, and a pressure control device 44. It is connected between the cooler 38 and the primary cooler 39.

This device eliminates the crude coke oven gas blower and is suitable for new coke oven installations.

In this case, even when gas is not passed to the dry main 43 side, it is preferable to always perform a cheap water shower to prevent a drop in temperature and to switch over immediately even if the system is stopped due to failure, inspection, etc. As described above, according to the present invention, the spouted bed cooler
A wet wall cooler can be used to recover heat while preventing coking at temperatures above 450°C, and a wet wall cooler can be used to recover heat while preventing coking at temperatures below 450°C. It has the remarkable effect of being able to operate stably and continuously for a long period of time. Furthermore, since the recovered steam is at a high temperature of 60 kg1c71 or more, it can be efficiently used for power generation, making it an excellent method in terms of utilization.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example of a heat recovery device used in the method of the present invention, FIG. 2 is an explanatory diagram of a spouted bed cooler used in the same device, and FIG. 3 is an explanatory diagram of a wet wall cooler used in the same device. FIG. 4 is an explanatory diagram showing another embodiment of the present invention. 1... Coke oven, 2... Rising pipe, 3
, 4... Gas pipe system, 5... Water seal valve, 6...
...Dry main, 7...Pressure control device,
8...Primary cooler, 9...
Pressure control device, 10...Coke oven gas blower, 11...Shutoff valve, 12...New air collection pipe, 13...Spouted bed cooler, 14・・・・・・
・Wet wall cooler, 15... Anhydrous water cooler, 16
...Flow rate control device, 17...Rough coke oven gas blower, 18...Outer cylinder, 19...
... Inner cylinder, 20 ... Particle splash prevention plate, 21 ...
... Pipeline for heat exchange fluid, 22 ... Particles, 2
3... Gas-liquid contact tank, 24... Gas-liquid separation tank,
25... Downstream pipe line, 26... Circulation pump, 27... Heat exchange fluid pipe line.

Claims (1)

[Claims] 1. A coke oven-generated raw material characterized in that coke oven gas generated in a coke oven carbonization chamber is once collected in a collection pipe, and then guided to a spouted bed cooler for heat exchange, and then to a wet wall cooler for heat exchange. Gas heat recovery method.