Vacuum potassium carbonate multistage desulfurization and decyanation device

Abstract

The utility model belongs to the technical field of coke oven gas desulfurization and decyanation, and particularly relates to a vacuum potassium carbonate multi-stage desulfurization and decyanation device which is characterized in that a tower body of a multi-stage single tower structure sequentially comprises a potassium carbonate washing section, a potassium hydroxide washing section, a sodium hydroxide washing section and an alkali mist removal section from bottom to top, a distributor I is arranged between the potassium carbonate washing section and the potassium hydroxide washing section and is connected with a desulfurization barren solution inlet, and an outlet I of a liquid breaking disc I is connected with a potassium hydroxide tank; a distributor II is arranged between the potassium hydroxide washing section and the sodium hydroxide washing section, a liquid breaking disc II is arranged above the distributor II, and a circulating pump is arranged on the pipeline; a distributor III is arranged between the sodium hydroxide washing section and the alkali mist removal section; and an outlet II of the liquid breaking disc I is communicated with the tower body below the distributor I through a short circuit pipe. The technical scheme has the advantages that the desulfurization and decyanation efficiency is improved, hydrogen sulfide and hydrogen cyanide can be efficiently absorbed by combining multiple washing modes, and the removal efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of coke oven gas desulfurization and decyanation, in particular to a vacuum potassium carbonate multi-stage desulfurization and decyanation device. Background Art

[0002] The vacuum potassium carbonate process is a commonly used method for desulfurization and decyanation of coke oven gas. The vacuum potassium carbonate process has many advantages such as low investment, low operating costs, and simple operation. Therefore, it is widely used in major steel enterprises such as Baosteel, Wuhan Iron and Steel, and Anshan Iron and Steel. This method mainly uses potassium carbonate solution as an absorbent to remove hydrogen sulfide and hydrogen cyanide from the coal gas by absorption. However, the sulfur and cyanide content in the coal gas treated by this method still cannot meet the standards for subsequent production and use of subsequent equipment, and further treatment is required. 2) Solutions of the existing technology: The existing solution is mainly to increase the sodium hydroxide consumption in the alkali washing section and add a fine desulfurization process after the vacuum potassium carbonate process. 3) Problems of existing technology: The existing vacuum potassium carbonate desulfurization and decyanation process has the following major problems: First, although the hydrogen sulfide and hydrogen cyanide that are not completely removed can be washed by increasing the consumption of sodium hydroxide, this will increase operating costs and will also lead to an increase in the sulfur and cyanide ion content in the wastewater treatment system, exceeding the load of the biochemical wastewater treatment device; second, the vacuum potassium carbonate process still needs to be equipped with a subsequent fine desulfurization process to meet the increasingly stringent needs of clean production, which not only increases investment, but also increases operating costs. In addition, the fine desulfurization process equipment is large and occupies a large area, which is not conducive to saving space.

[0003] Chinese utility model patent application number 201610749903.9 discloses a process and apparatus for treating alkali liquor in the alkali washing section of coke oven gas desulfurization and decyanation. The alkali liquor discharged from the alkali washing section of the coke oven gas desulfurization and decyanation process is fed into an alkali liquor desorption tower, where it is countercurrently contacted with steam to remove cyanide ions from the alkali liquor. HCN gas, thermally decomposed at the top of the alkali liquor desorption tower, is fed to the top of a residual ammonia distillation tower, where it is distilled along with the ammonia gas at the top of the residual ammonia distillation tower. Alternatively, the HCN gas thermally decomposed at the top of the alkali liquor desorption tower is fed into the acid gas output pipeline at the top of the regeneration tower of a vacuum potassium carbonate desulfurization process. At the bottom of the alkali liquor desorption tower, the alkali liquor after the desorption reaction flows by gravity to the residual ammonia distillation tower for the subsequent distillation process to decompose fixed ammonium. This process requires separate desorption and distillation towers, which occupies a large area, is not conducive to space conservation, and has high operating costs. Utility Model Content

[0004] The purpose of the utility model is to provide a vacuum potassium carbonate multi-stage desulfurization and decyanation device, which overcomes the shortcomings of the existing technology and adopts a multi-stage single-tower structure. Under the premise of not increasing the alkali consumption, it improves the removal efficiency of hydrogen sulfide, hydrogen cyanide and alkali mist contained in coke oven gas; reduces the content of sulfur and cyanide ions entering the wastewater treatment system, and reduces the treatment load of the biochemical wastewater treatment device; meets the increasingly stringent needs of clean production while reducing the equipment scale and saving space and other technical problems.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A vacuum potassium carbonate multi-stage desulfurization and decyanation device has a multi-stage single-tower structure. The tower body comprises, from bottom to top, a potassium carbonate washing section, a potassium hydroxide washing section, a sodium hydroxide washing section and an alkali mist removal section. A gas outlet is provided at the top of the tower body, a desulfurization rich liquid outlet is provided at the bottom of the tower body, and a gas inlet is provided on one side of the bottom of the tower body. A distributor 1 is provided between the potassium carbonate washing section and the potassium hydroxide washing section, a liquid cut-off tray 1 is provided above the distributor 1, the distributor 1 is connected to the desulfurization lean liquid inlet, and an outlet 1 of the liquid cut-off tray 1 is connected to a potassium hydroxide tank; a distributor 2 is provided between the potassium hydroxide washing section and the sodium hydroxide washing section, a liquid cut-off tray 2 is provided above the distributor 2, the distributor 2 is connected to the outlet of the potassium hydroxide tank via a pipeline, a circulating pump is provided on the pipeline, and the outlet of the liquid cut-off tray 2 is connected to an ammonia distillation device; a distributor 3 is provided between the sodium hydroxide washing section and the alkali mist removal section, the distributor 3 is connected to the sodium hydroxide solution inlet; and an outlet 2 of the liquid cut-off tray 1 is connected to the tower body below the distributor 1 via a short-circuit pipe.

[0007] Furthermore, the structures of the liquid-blocking tray 1 and the liquid-blocking tray 2 are the same, including a sealing plate and an umbrella-shaped cap. The sealing plate is provided with an air vent in the center, and a water retaining ring plate is provided around the air vent. The umbrella-shaped cap is provided above the air vent, and the height of the water retaining ring plate is not less than 80 mm.

[0008] Furthermore, the structures of the distributor 1, the distributor 2 and the distributor 3 are the same, including an annular tube with multiple nozzles provided along the bottom of the annular tube.

[0009] Furthermore, the potassium hydroxide tank is provided with a potassium hydroxide supply pipe and a soft water supply pipe.

[0010] Furthermore, the potassium hydroxide washing section is any one of a tower plate, a tower tray or a filler.

[0011] Furthermore, the potassium carbonate washing section is any one of the structures of a tower plate, a tower tray or a packing.

[0012] Furthermore, the sodium hydroxide washing section is any one of a tower plate, a tower tray or a filler.

[0013] Furthermore, a wire mesh demister is provided in the alkali mist removal section.

[0014] Compared with the existing technology, the beneficial effects of this technical solution are as follows:

[0015] 1) Improve desulfurization and decyanation efficiency: The utility model can efficiently absorb hydrogen sulfide and hydrogen cyanide by combining multiple washing methods, thereby improving the removal efficiency of hydrogen sulfide and hydrogen cyanide contained in coke oven gas.

[0016] 2) Reduced sodium hydroxide consumption: By optimizing the design of the washing section, the present invention allows potassium hydroxide solution to be washed in a closed-loop cycle within the washing section, thereby improving the effective utilization rate of potassium hydroxide. Furthermore, by optimizing the method of introducing potassium hydroxide into the desulfurization regeneration system, the desulfurization and decyanation efficiency is increased with the same potassium hydroxide consumption, thereby significantly reducing subsequent sodium hydroxide consumption. Furthermore, by providing an alkali mist removal section, the alkali mist can be controlled within the device, further reducing sodium hydroxide consumption. Therefore, the problem of increased sulfur and cyanide ion content in the wastewater treatment system due to the large-scale use of sodium hydroxide is avoided.

[0017] 3) Save space and investment: Compared with the existing technology, the utility model has a compact structure and occupies a small area, which not only saves space but also reduces equipment investment.

[0018] 4) Meeting the needs of clean production: The utility model can effectively reduce the sulfur and cyanide content in coal gas, meeting the increasingly stringent needs of clean production. The solution is advanced, so it can be widely used in the coking industry. It has important reference value for the equipment design and layout in the coking field. The utility model has broad market demand and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model.

[0020] In the figure: 1-potassium carbonate washing section, 2-potassium hydroxide washing section, 3-sodium hydroxide washing section, 4-alkaline mist removal section, 5-liquid cut-off plate 1, 6-potassium hydroxide tank, 7-circulating pump, 8-liquid cut-off plate 2, 9-distributor 1, 10-distributor 2, 11-wire mesh demister, 12-gas inlet, 13-desulfurization lean liquid inlet, 14-distributor 3, 15-waste sodium hydroxide outlet, 16-sodium hydroxide solution inlet, 17-gas outlet, 18-short-circuit pipe, 19-sealing plate, 20-umbrella cap, 21-water retaining ring plate. DETAILED DESCRIPTION

[0021] The technical solutions of the present invention will be described clearly and completely below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0022] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the specific embodiments required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation methods of the utility model. For ordinary technicians in this field, other specific embodiments can be obtained based on these specific embodiments without paying creative work.

[0023] The components of the embodiments of the present invention generally described and shown in the specific embodiments herein can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the claimed invention, but rather represents only selected embodiments of the present invention.

[0024] See Figure 1 , is a schematic diagram of the structure of an embodiment of a vacuum potassium carbonate multi-stage desulfurization and decyanation device of the utility model. In a multi-stage single tower structure, it includes a potassium carbonate washing section 1, a potassium hydroxide washing section 2, a sodium hydroxide washing section 3 and an alkali mist removal section 4 from bottom to top. A gas outlet 17 is provided at the top of the tower body, a desulfurization rich liquid outlet 12 is provided at the bottom of the tower body, and a gas inlet 12 is provided on one side of the bottom of the tower body. A distributor 10 is provided between the potassium carbonate washing section 1 and the potassium hydroxide washing section 2. A liquid cut-off plate 5 is provided above the distributor 10. The distributor 10 is connected to the desulfurization lean liquid inlet 13. The liquid cut-off plate 5 is provided above the distributor 10. The distributor 10 is connected to the desulfurization lean liquid inlet 13. Outlet 1 of tray 1 5 is connected to potassium hydroxide tank 6; distributor 2 9 is provided between potassium hydroxide washing section 2 and sodium hydroxide washing section 3, and liquid shut-off tray 2 8 is provided above distributor 2 9. Distributor 2 9 is connected to the outlet of potassium hydroxide tank 6 through a pipeline, and a circulation pump 7 is provided on the pipeline. The waste sodium hydroxide outlet 15 of liquid shut-off tray 2 8 is connected to an ammonia distillation device; distributor 3 14 is provided between sodium hydroxide washing section 3 and alkali mist removal section 4, and distributor 3 14 is connected to sodium hydroxide solution inlet 16; outlet 2 of liquid shut-off tray 1 5 is connected to the tower body below distributor 10 through a short-circuit pipe 18.

[0025] Liquid shut-off tray 1 5 and liquid shut-off tray 2 8 share the same structure, including a sealing plate 19 and an umbrella-shaped cap 20. Sealing plate 19 has a centrally located vent, surrounded by a water retaining ring 21. Umbrella-shaped cap 20 is located above the vent, and the height of water retaining ring 21 is 100 mm. Distributors 1 10, 2 9, and 3 14 share the same structure, including an annular tube with multiple nozzles located along its bottom. Potassium hydroxide tank 6 is equipped with a potassium hydroxide supply pipe and a soft water supply pipe.

[0026] The potassium hydroxide washing section 2 is packed with Lareau rings and has a height of 1m. It can also be constructed with plates or trays. The potassium carbonate washing section 1 is packed with Lareau rings and has a height of 14m. It can also be constructed with plates or trays. The sodium hydroxide washing section 3 is a tray-type structure with three trays. It can also be constructed with trays or packing. The alkaline mist removal section 4 is equipped with a wire mesh demister 11.

[0027] Coke oven gas enters from gas inlet 12, and the flow rate of coke oven gas is 126000Nm 3 / h, the temperature is 28℃, and the pressure is 12kPa. The coke oven gas enters the tower body from the lower part of the potassium carbonate washing section 1. In the potassium carbonate washing section 1, the coke oven gas is countercurrently contacted with the regenerated lean liquid containing 80% free K2CO3. Most of the hydrogen sulfide and hydrogen cyanide in the coke oven gas (accounting for 95-97% by weight) are absorbed, and the desulfurized rich liquid containing 30% free K2CO3 leaves the device to go to the regeneration device. The coke oven gas then passes through the liquid cut-off plate 5 and enters the potassium hydroxide washing section 2. In this section, the hydrogen sulfide and hydrogen cyanide in the coke oven gas are further absorbed by the circulating potassium hydroxide solution to 50mg / m 3 Coke oven gas, circulated potassium hydroxide solution (concentration of 5% wt) enters potassium hydroxide tank 6, which is replenished with fresh potassium hydroxide (concentration of 48% wt) and soft water for renewal. A closed potassium hydroxide cycle is formed by circulating pump 7. Excess potassium hydroxide solution is introduced into the lower potassium carbonate washing section 1 through liquid cut-off plate 1. The coke oven gas then passes through liquid cut-off plate 2 8 and enters sodium hydroxide washing section 3. Sodium hydroxide solution (concentration of 5% wt) can deeply remove hydrogen sulfide and hydrogen cyanide in the coke oven gas to 20 mg / m 3 For coke oven gas, this sodium hydroxide scrubbing section can be selectively opened according to the requirements of hydrogen sulfide and hydrogen cyanide content at the coke oven gas outlet to ensure that the hydrogen sulfide and hydrogen cyanide content at the coke oven gas outlet is 20-50 mg / m 3 Finally, after the coke oven gas passes through the mist collector 4 to remove the alkaline mist carried by it, it leaves the tower body of this device. At this time, the hydrogen sulfide and hydrogen cyanide content at the coke oven gas outlet can reach 20mg / m3 coke oven gas, meeting the emission requirements.

[0028] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A vacuum potassium carbonate multi-stage desulfurization and decyanation device, characterized in that: It is a multi-stage single-tower structure. The tower body includes, from bottom to top, a potassium carbonate washing section, a potassium hydroxide washing section, a sodium hydroxide washing section and an alkali mist removal section. A gas outlet is provided at the top of the tower body, a desulfurization rich liquid outlet is provided at the bottom of the tower body, and a gas inlet is provided on one side of the bottom of the tower body. A distributor 1 is provided between the potassium carbonate washing section and the potassium hydroxide washing section. A liquid shut-off plate 1 is provided above the distributor 1. The distributor 1 is connected to the desulfurization lean liquid inlet, and an outlet 1 of the liquid shut-off plate 1 is connected to the potassium hydroxide tank; a distributor 2 is provided between the potassium hydroxide washing section and the sodium hydroxide washing section. A liquid shut-off plate 2 is provided above the distributor 2. The distributor 2 is connected to the outlet of the potassium hydroxide tank through a pipeline, a circulating pump is provided on the pipeline, and the outlet of the liquid shut-off plate 2 is connected to the ammonia distillation device; a distributor 3 is provided between the sodium hydroxide washing section and the alkali mist removal section. The distributor 3 is connected to the sodium hydroxide solution inlet; an outlet 2 of the liquid shut-off plate 1 is connected to the tower body below the distributor 1 through a short-circuit pipe.

2. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The structures of the liquid-blocking tray 1 and the liquid-blocking tray 2 are the same, including a sealing plate and an umbrella-shaped cap. The sealing plate is provided with a vent in the center, and a water retaining ring plate is provided around the vent. The umbrella-shaped cap is provided above the vent, and the height of the water retaining ring plate is not less than 80 mm.

3. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The first distributor, the second distributor and the third distributor have the same structure, including an annular tube with a plurality of nozzles arranged along the bottom of the annular tube.

4. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The potassium hydroxide tank is provided with a potassium hydroxide supply pipe and a soft water supply pipe.

5. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The potassium hydroxide washing section is any one of a tower plate, a tower tray or a filler.

6. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The potassium carbonate washing section is any one of a tower plate, a tower tray or a filler.

7. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: The sodium hydroxide washing section is any one of a tower plate, a tower tray or a filler.

8. A vacuum potassium carbonate multi-stage desulfurization and decyanation device according to claim 1, characterized in that: A wire mesh demister is provided in the alkali mist removal section.

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