A high-efficiency caustic washing device for difluorochloroethane

Abstract

The utility model relates to a kind of difluoro monochloroethane high-efficiency caustic washing device, second caustic washing tower upper alkali distributor is sent into by alkali storage tank in turn through first delivery pump, first regulating valve, first flowmeter, first caustic washing heat exchanger, second caustic washing tower bottom is connected with second crystallizing tank, second crystallizing tank is sent into first caustic washing tower upper alkali distributor through second delivery pump, second regulating valve, second flowmeter, second caustic washing heat exchanger in turn, first caustic washing tower bottom is connected with first crystallizing tank, first crystallizing tank bottom is connected with crystallization collection tank, first crystallizing tank middle lower portion or lower portion is divided into two ways by crystallization circulating pipeline with crystallization circulating pump, one way returns and connects first crystallizing tank top, another way is sent second crystallizing tank top by transfer pump.The device structure is simple, can effectively give consideration to two-stage caustic washing efficiency, reduce equipment, production hidden danger caused by salt content attachment simultaneously, improve service life and ensure caustic washing quality.

Description

Technical Field

[0001] This utility model relates to an alkaline washing device, specifically a difluorochloroethane high-efficiency alkaline washing device. Background Technology

[0002] In existing difluorochloroethane chlorination production technologies, a two-stage alkaline washing process is generally used to remove hydrogen chloride and unreacted chlorine, byproducts of the process. During alkaline washing, hydrogen chloride and chlorine react with sodium hydroxide to neutralize the sodium chloride, producing a large amount of sodium chloride. After long-term operation, a large amount of salt adheres to the packing section of the alkaline washing tower, increasing the internal resistance and making it prone to channeling and flow deviation. This reduces the washing effect, affects product quality, and in severe cases, causes corrosion to production equipment, shortens its service life, or even renders the equipment unusable. Summary of the Invention

[0003] This invention provides a high-efficiency difluorochloroethane alkaline washing device with a simple structure that can effectively balance the efficiency of two-stage alkaline washing, reduce equipment and production hazards caused by salt adhesion, improve service life, and ensure the quality of alkaline washing.

[0004] The technical solution adopted by this utility model is: a high-efficiency alkaline washing device for difluorochloroethane, comprising first and second alkaline washing towers, first and second crystallization tanks, and an alkaline solution storage tank, characterized in that: the alkaline solution distributor in the upper part of the second alkaline washing tower is fed into the alkaline solution storage tank sequentially through a first transfer pump, a first regulating valve, a first flow meter, and a first alkaline washing heat exchanger; the bottom of the second alkaline washing tower is connected to the second crystallization tank; the second crystallization tank is fed into the alkaline solution distributor in the upper part of the first alkaline washing tower sequentially through a second transfer pump, a second regulating valve, a second flow meter, and a second alkaline washing heat exchanger; the bottom of the first alkaline washing tower is connected to the first crystallization tank; the bottom of the first crystallization tank is connected to a crystallization collection tank; the lower part of the first crystallization tank is divided into two paths through a crystallization circulation pipeline with a crystallization circulation pump, one path returning to the top of the first crystallization tank, and the other path being sent to the top of the second crystallization tank via a transfer pump.

[0005] The lower part of the second crystallizer is divided into two paths via a crystallization circulation pipeline equipped with a crystallization circulation pump. One path returns to the top of the second crystallizer, and the other path is sent to the alkali distributor at the top of the first alkali washing tower via the second delivery pump, the second regulating valve, the second flow meter, and the second alkali washing heat exchanger.

[0006] The first and second crystallization tanks are equipped with cooling jackets.

[0007] The tops of the first and second crystallization tanks are also connected back to the bottoms of the first and second alkali washing towers via return gas pipes, respectively.

[0008] The second crystallizer has three branches in the lower part or the bottom part of the crystallization circulation pipeline with crystallization circulation pump. One branch is returned to the top of the second crystallizer. Another branch is sent to the alkaline liquid distributor at the top of the first alkaline washing tower in sequence through the second transfer pump, the second regulating valve, the second flow meter, and the second alkaline washing heat exchanger. The third branch is connected to the sodium hypochlorite storage tank in sequence through the liquid outlet pump and the liquid outlet valve.

[0009] Both the first and second alkali washing towers are equipped with top condensers.

[0010] The beneficial effects of this invention are as follows: By employing a tiered alkali supply path—comprising an alkali storage tank, a second alkali scrubbing tower, a second crystallizing tank, and a first alkali scrubbing tower—both alkali utilization and impurity removal efficiency are optimized. Based on the impurity gradient of the raw gas, the second alkali scrubbing tower treats gas with a lower concentration of acidic impurities after preliminary purification, while the first alkali scrubbing tower treats gas with an initial high concentration of acidic impurities. By first feeding the alkali from the storage tank into the second alkali scrubbing tower, deep purification of the low-impurity gas is ensured, preventing impurity exceedances due to insufficient alkali concentration. Furthermore, the alkali used in the second alkali scrubbing tower, after being cooled and crystallized in the jacket of the second crystallizing tank to precipitate NaCl, still retains sufficient NaOH, which is then supplied to the first alkali scrubbing tower. This perfectly matches the neutralization requirements of the high-impurity gas in the first tower, avoiding waste caused by directly treating high-impurity gas with fresh alkali. The tiered mode of high-concentration alkali for fine washing and low-concentration alkali for coarse washing minimizes the consumption of fresh alkali and reduces the risk of salt adhesion in the packing sections of both towers, further suppressing channel flow deviation.

[0011] Meanwhile, the alkaline solution after NaCl crystallization is returned from the first crystallizer to the second crystallizer, forming a closed-loop optimized circulation of the alkaline solution, significantly improving system stability and economy. The first crystallizer treats the waste liquid after the high-impurity reaction in the first alkaline washing tower, which has a high NaCl content and relatively low alkalinity. After being returned to the second crystallizer, it can be used to treat the low-impurity waste liquid. The higher alkalinity environment further promotes the precipitation of residual NaCl, improving salt recovery efficiency. At the same time, the low-concentration alkaline solution from the first crystallizer can supplement the total amount of alkaline solution in the second crystallizer, reducing the second crystallizer's dependence on fresh alkaline solution and avoiding resource waste caused by direct discharge of low-concentration alkaline solution. In addition, a third branch from the second crystallizer connects to a sodium hypochlorite storage tank, realizing the resource utilization of by-products. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the structure of this utility model.

[0013] In the diagram: 1. Inlet pipe; 2. First alkaline washing tower; 3. First tower top condenser; 4. Second alkaline washing tower; 5. Second tower top condenser; 6. Alkaline solution storage tank; 7. First transfer pump; 8. First regulating valve; 9. First flow meter; 10. First alkaline washing heat exchanger; 11. Second crystallization tank; 12. Cooling jacket; 13. Second transfer pump; 14. Second regulating valve; 15. Second flow meter; 16. Second alkaline washing heat exchanger; 17. First crystallization tank; 18. Crystallization collection tank; 19. Crystallization circulation pump; 20. Crystallization circulation pipeline; 21. Transfer pump; 22. Return gas pipe; 23. Liquid discharge pump; 24. Liquid discharge valve; 25. Sodium hypochlorite storage tank. Detailed Implementation

[0014] The following explanation, in conjunction with the accompanying drawings, will provide further details.

[0015] Figure 1 As shown, a high-efficiency alkaline washing device for difluorochloroethane includes an inlet pipe 1, a first alkaline washing tower 2, a first tower top condenser 3, a second alkaline washing tower 4, a second tower top condenser 5, an alkaline solution storage tank 6, a first transfer pump 7, a first regulating valve 8, a first flow meter 9, a first alkaline washing heat exchanger 10, a second crystallization tank 11, a cooling jacket 12, a second transfer pump 13, a second regulating valve 14, a second flow meter 15, a second alkaline washing heat exchanger 16, a first crystallization tank 17, a crystallization collection tank 18, a crystallization circulation pump 19, a crystallization circulation pipeline 20, a transfer pump 21, a return gas pipe 22, a liquid outlet pump 23, a liquid outlet valve 24, and a sodium hypochlorite storage tank 25.

[0016] The inlet pipe 1 connects to the lower part of the first alkali washing tower 2. The top of the first alkali washing tower 2 connects to the first tower top condenser 3. The first tower top condenser 3 connects to the lower part of the second alkali washing tower 4. The top of the second alkali washing tower 4 is equipped with a second tower top condenser 5. The alkali storage tank 6 connects to the alkali distributor at the upper part of the second alkali washing tower 4 via the first transfer pump 7, the first regulating valve 8, the first flow meter 9, and the first alkali washing heat exchanger 10. The bottom of the second alkali washing tower 4 connects to the second crystallization tank 11. The second crystallization tank 11 is equipped with a cooling jacket 12. The top of the second crystallization tank 11 connects to the lower part of the second alkali washing tower 4 via the return gas pipe 22. The bottom of the second crystallization tank 11 connects to the crystallization collection tank 18. The lower middle or lower part of the second crystallization tank 11 connects to a crystallization circulation pipeline 20 equipped with a crystallization circulation pump 19. The crystallization circulation pipeline 20 is divided into three branches. The first branch connects to the second The top of crystallizer 11 is connected to the alkaline liquid distributor at the top of the first alkaline washing tower 2 via the second transfer pump 13, the second regulating valve 14, the second flow meter 15, and the second alkaline washing heat exchanger 16. The third path is connected to the sodium hypochlorite storage tank 25 via the outlet pump 23 and the outlet valve 24. The bottom of the first alkaline washing tower 2 is connected to the first crystallizer 17. The first crystallizer 17 is equipped with a cooling jacket. The top of the first crystallizer 17 is connected to the lower part of the first alkaline washing tower 2 via a return gas pipe. The bottom of the first crystallizer 17 is connected to the crystallization collection tank. The middle and lower part of the first crystallizer 11 is divided into three paths via a crystallization circulation pipeline with a crystallization circulation pump. The first path is returned to the top of the first crystallizer 11. The second path is sent to the top of the second crystallizer 11 via a transfer pump 21. The third path is connected to the sodium hypochlorite storage tank 25 via the outlet pump 23 and the outlet valve 24.

Claims

1. A high-efficiency alkaline washing device for difluorochloroethane, comprising first and second alkaline washing towers, first and second crystallization tanks, and an alkaline solution storage tank, characterized in that: The alkali solution in the upper part of the second alkali washing tower is fed into the alkali solution distributor by the alkali storage tank in sequence through the first transfer pump, the first regulating valve, the first flow meter, and the first alkali washing heat exchanger. The bottom of the second alkali washing tower is connected to the second crystallization tank. The second crystallization tank is fed into the upper part of the first alkali washing tower by the second transfer pump, the second regulating valve, the second flow meter, and the second alkali washing heat exchanger in sequence. The bottom of the first alkali washing tower is connected to the first crystallization tank. The bottom of the first crystallization tank is connected to the crystallization collection tank. The middle or lower part of the first crystallization tank is divided into two paths by the crystallization circulation pipeline with a crystallization circulation pump. One path returns to the top of the first crystallization tank, and the other path is sent to the top of the second crystallization tank by the transfer pump.

2. The high-efficiency alkaline washing device for difluorochloroethane according to claim 1, characterized in that: The lower part of the second crystallizer is divided into two paths via a crystallization circulation pipeline equipped with a crystallization circulation pump. One path returns to the top of the second crystallizer, and the other path is sent to the alkali distributor at the top of the first alkali washing tower via the second delivery pump, the second regulating valve, the second flow meter, and the second alkali washing heat exchanger.

3. The high-efficiency alkaline washing device for difluorochloroethane according to claim 1, characterized in that: The first and second crystallization tanks are equipped with cooling jackets.

4. The high-efficiency alkaline washing device for difluorochloroethane according to claim 1, characterized in that: The tops of the first and second crystallization tanks are also connected back to the bottoms of the first and second alkali washing towers via return gas pipes, respectively.

5. A high-efficiency alkaline washing device for difluorochloroethane according to any one of claims 1-4, characterized in that: The second crystallizer has three branches in the lower part or the bottom part of the crystallization circulation pipeline with crystallization circulation pump. One branch is returned to the top of the second crystallizer. Another branch is sent to the alkaline liquid distributor at the top of the first alkaline washing tower in sequence through the second transfer pump, the second regulating valve, the second flow meter, and the second alkaline washing heat exchanger. The third branch is connected to the sodium hypochlorite storage tank in sequence through the liquid outlet pump and the liquid outlet valve.

6. A high-efficiency alkaline washing device for difluorochloroethane according to any one of claims 1-4, characterized in that: Both the first and second alkali washing towers are equipped with top condensers.

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