Method for preventing blockage of vacuum potassium carbonate desulfurized acid gas pipeline

Abstract

The invention discloses a method for preventing a vacuum potassium carbonate desulfurized acid gas pipeline from being blocked, and belongs to the field of coking product recovery. The method comprises the following steps: arranging a furnace end of an acid-making incinerator / Claus furnace close to a desulfurization regeneration vacuum pump, and linearly arranging an acid gas pipeline. Two mutually-standby acid gas pipelines are arranged, flushing water pipes are arranged at the ends of the pipelines, and a mist catcher, a corresponding separation tank and an acid gas water seal are arranged in front of an incinerator / Claus furnace. The washing oil mist catcher is arranged at the outlet of the benzene washing tower, so that washing oil in desulfurization liquid is reduced, and the content of impurities in acid gas is reduced; a desulfurization pregnant solution pipeline filter is arranged, and a reasonable operation cycle is set according to the quality of the solution, so that components such as pulverized coal and oil in the pregnant solution are further reduced, and the purpose of reducing the content of impurities in the acid gas is achieved. The large safety risk of acid gas leakage possibly existing in the blind plate pumping and blocking process of acid gas pipeline blocking clearing operation is eradicated, and the risk that hydrogen sulfide in coke oven gas exceeds the standard in the blocking clearing process can be reduced.

Description

Technical Field

[0001] The invention relates to a coking product recovery process, in particular to a method for preventing a vacuum potassium carbonate desulfurized gas pipeline from being blocked. Background Art

[0002] Coke oven gas (COG) is a combustible gas produced during the high-temperature dry distillation of coal in a coke oven. Its H2S content before treatment is generally 8-10g / m3. H2S is an acidic gas that corrodes equipment and pipelines. During combustion, it converts to SO2, which also seriously pollutes the environment. Therefore, H2S removal from the gas is essential. Commonly used desulfurization methods include wet oxidation and chemical absorption. The vacuum potassium carbonate method is a chemical absorption method. The process flow is as follows: After benzene washing, the gas enters the desulfurization tower. After a small amount of oil is removed through the lower mist catcher, the gas comes into countercurrent contact with the desulfurization lean solution from bottom to top, absorbing the H2S in the gas. The desulfurization process reaction equation is: K2CO3 + H2S → KHCO3 + KHS.

[0003] The desulfurized rich liquid, which has absorbed H2S, flows by gravity into the rich liquid tank. The rich liquid is pumped out by a rich liquid pump and exchanged with the hot lean liquid exiting the bottom of the regeneration tower before entering the regeneration tower for regeneration. Within the regeneration tower, the rich liquid countercurrently contacts the rising steam from the bottom of the tower, desorbing the H2S from the rich liquid under vacuum. The desorbed lean liquid is pumped out from the bottom of the regeneration tower by a lean liquid pump, sent through the lean-rich liquid heat exchanger for heat exchange, and cooled in the lean liquid cooler before being recycled to the desulfurization tower. The acid gas exiting the regeneration tower is dehydrated by a condenser cooler and separator, and then the acid gas (H2S) is sent by a vacuum pump to the WSA acid plant or Claus furnace for treatment. The regeneration principle: KHS + KHCO3 → K2CO3 + H2S.

[0004] The desulfurized rich liquid contains impurities such as secondary salts, wash oil, and naphthalene, which are desorbed along with the hydrogen sulfide gas in the regeneration tower and accumulate in the acid gas pipeline transported to the incinerator by the vacuum pump, causing blockage in the pipeline. Summary of the Invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for preventing blockage of vacuum potassium carbonate desulfurized gas pipelines; fundamentally reduce the operation of clearing blockages in acid gas pipelines, eliminate the safety risk of acid gas leakage during blind plate removal operations, reduce the labor load of personnel, and reduce maintenance costs.

[0006] Technical solution: A method for preventing blockage of a vacuum potassium carbonate desulfurized gas pipeline, comprising the following steps:

[0007] S1. The burner of the acid incinerator / Claus furnace is placed close to the desulfurization regeneration vacuum pump, and the acid gas pipeline is arranged in a straight line;

[0008] S2. Set up two backup acid gas pipelines, install flushing water pipes at the ends of the pipelines, and install a mist collector and corresponding separation tank and acid gas water seal before entering the incinerator / Claus furnace;

[0009] S3. Install a washing oil mist collector at the outlet of the benzene washing tower to reduce the washing oil in the desulfurization liquid, thereby reducing the impurity content in the acid gas; and install a desulfurization rich liquid pipeline filter, set a reasonable operation cycle according to the solution quality, and further reduce the coal powder, oil and other components in the rich liquid, so as to achieve the purpose of reducing the impurity content in the acid gas.

[0010] Preferably, in step S2, corresponding gate valves are arranged between the two acid gas pipelines serving as backup for each other to ensure effective shutoff.

[0011] Preferably, in step S2, vacuum condensate is used as the flushing water in the flushing water pipe, without increasing the amount of wastewater.

[0012] Preferably, in step S2, the flushing water is long-flowing water, which is discharged to the surrounding drain tank through the water.

[0013] Preferably, the total length of the acid gas pipeline is less than 40 m, the gas flow rate in the acid gas pipeline is less than 3.0 m / s, and the slope of the acid gas pipeline is 5-10°.

[0014] Beneficial Effects: This eliminates the significant safety risk of acid gas leakage during the removal of blind plates during acid gas pipeline clearing operations, significantly reducing the workload of maintenance workers and lowering maintenance costs. It also reduces the risk of excessive hydrogen sulfide in coke oven gas during the clearing process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the floor plan;

[0016] Figure 2 It is a process flow diagram of this method. DETAILED DESCRIPTION

[0017] In order to make the technical solution of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] A method for preventing blockage of a vacuum potassium carbonate desulfurized gas pipeline, comprising:

[0019] (1) The burner of the acid incinerator / Claus furnace should be placed close to the desulfurization regeneration vacuum pump, and the acid gas pipeline should be arranged in a straight line with as few elbows as possible, such as Figure 1 shown.

[0020] (2) Figure 2As shown, two acid gas pipelines that can serve as backup for each other are set up, and corresponding gate valves are configured to ensure effective shut-off. A flushing water pipe is set at the end of the pipeline, and vacuum condensate can be used as the flushing water, which does not increase the amount of wastewater generated. A mist collector and corresponding separation tank and acid gas water seal are set before entering the incinerator / Claus furnace. The flushing water is long-flow water and is discharged to the nearby vent tank through the water seal.

[0021] The acid gas pipeline parameters are as follows: ① The total length should be less than 40m (from the vacuum pump outlet main pipe end flange to the incinerator head flange); ② The number of pipelines should be more than 2 (1 in operation and 1 in standby); ③ The gas flow rate in the pipeline should be less than 3.0m / s; ④ The pipeline slope is 5~10°.

[0022] (3) An oil washing mist collector is installed at the outlet of the benzene washing tower to reduce the washing oil in the desulfurization liquid, thereby reducing the impurity content in the acid gas. A desulfurization rich liquid pipeline filter is installed, and a reasonable operation cycle is set according to the solution quality to further reduce the components such as coal powder and oil in the rich liquid, thereby achieving the purpose of reducing the impurity content in the acid gas.

[0023] Example

[0024] Baosteel Zhanjiang Iron & Steel Co., Ltd.'s No. 1 and No. 2 blast furnace systems' coal cleaning project uses a vacuum potassium carbonate method for desulfurization and began production in July 2015. During operation, the acid gas pipeline required a one-month cleaning cycle after blockage.

[0025] (1) The acid gas pipelines of the coal refinery project of the No. 1 and No. 2 blast furnace systems were renovated according to the above plan: ① The acid gas pipelines were changed to two, and the pipe diameters were increased to reduce the flow rate of the acid gas in the pipelines; ② A long-flow flushing water was installed. Due to the limitations of the original design, other corresponding measures were not taken.

[0026] (2) The design of the coal refinery project for the three blast furnace systems began in 2019 and was put into operation in 2021. The design of the acid gas pipeline for vacuum potassium carbonate desulfurization follows the above principles and plans: ① The burner head of the incinerator and the vacuum pump are arranged close to each other, with a distance of only 37m. ② There are two acid gas pipelines designed, and the vacuum condensate is used as pipeline flushing water. A mist collector and acid gas water seal are installed to ensure that the flushing water is always open. ③ The pipeline design size is DN300, corresponding to a designed acid gas volume of 700Nm3 / h, with a slope of about 5°. ④ A mist collector is installed at the outlet of the benzene washing tower, and a pipeline filter is configured for the desulfurization rich liquid.

[0027] Results: ① After the renovation of the coal cleaning project for the No. 1 and No. 2 blast furnace systems, the frequency of cleaning operations has been reduced to once every three months. ② Since the coal cleaning project for the No. 3 blast furnace system went into operation in April 2021, the sour gas pipeline of the desulfurization unit has been in continuous operation for 22 months with zero clearing operations.

[0028] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preventing blockage of a vacuum potassium carbonate desulfurized gas pipeline, characterized in that: The following steps are involved: S1. The burner of the acid incinerator / Claus furnace is placed close to the desulfurization regeneration vacuum pump, and the acid gas pipeline is arranged in a straight line; S2. Set up two backup acid gas pipelines, install flushing water pipes at the ends of the pipelines, and install a mist collector and corresponding separation tank and acid gas water seal before entering the incinerator / Claus furnace; S3. Install a washing oil mist collector at the outlet of the benzene washing tower to reduce the washing oil in the desulfurization liquid, thereby reducing the impurity content in the acid gas; and install a desulfurization rich liquid pipeline filter, set a reasonable operation cycle according to the solution quality, and further reduce the coal powder, oil and other components in the rich liquid, so as to achieve the purpose of reducing the impurity content in the acid gas.

2. The method for preventing vacuum potassium carbonate desulfurization gas pipeline from being blocked according to claim 1, wherein: In step S2, corresponding gate valves are arranged between the two acid gas pipelines serving as backup for each other to ensure effective shutoff.

3. The method for preventing vacuum potassium carbonate desulfurization gas pipeline from being blocked according to claim 1, wherein: In step S2, vacuum condensate is used as the flushing water in the flushing water pipe, without increasing the amount of wastewater.

4. The method for preventing vacuum potassium carbonate desulfurization gas pipeline from being blocked according to claim 1, wherein: In step S2, the flushing water is long-flowing water and is discharged to the surrounding drain tank through the water.

5. The method for preventing vacuum potassium carbonate desulfurization gas pipeline from being blocked according to claim 1, wherein: The total length of the acid gas pipeline is less than 40m, the gas flow rate in the acid gas pipeline is less than 3.0m / s, and the slope of the acid gas pipeline is 5-10°.

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