Low-acidity high-purity difluorochloroethane alkali washing system

Abstract

The utility model relates to a low-acidity high-purity difluorochloroethane alkali washing system, which is characterized in that two stages of alkali washing towers are respectively matched with an alkali washing tank, a first alkali washing tower is connected with a first alkali washing tank, the first alkali washing tank is divided into three paths after passing through a first alkali washing pump and a first cooler, and the three paths are respectively connected with the first alkali washing tank, a sodium hypochlorite storage tank and a first condenser and then are connected with the upper part of the first alkali washing tower; a cooling liquid inlet pipe of the first cooler is connected with a flow regulating valve, the bottom of a second alkaline washing tower connected with the top of the first alkaline washing tower, the structures of the second alkaline washing tower and the second alkaline washing tank are the same as those of the first alkaline washing tower and the first alkaline washing tank, and the top of the second alkaline washing tower is connected with an alkaline washing separator buffer. The controller is used for collecting the temperature of alkali liquor sent out of the alkali washing tank and the cooler and entering the alkali washing tower, so that the opening degree of the flow regulating valve is controlled to enable the alkali liquor to be sent into the alkali washing tower within a certain range, and alkali washing efficiency is improved.

Description

Technical Field

[0001] The utility model relates to an alkali washing device, in particular to a low-acidity high-purity dichlorofluoroethane alkali washing system. Background Art

[0002] In the existing industrial production of dichloroethane, the process of photochlorination reaction of difluoroethane is adopted. The produced dichlorofluoroethane contains a large amount of chlorine gas and hydrochloric acid. During the purification process, hydrochloric acid is first absorbed by a hydrochloric acid absorber, then sent to an alkali washing tower to further remove hydrochloric acid and chlorine gas, and then sent to a water washing process. However, the temperature rise of the alkali solution during alkali washing directly affects the washing effect of hydrochloric acid, which directly leads to unclear gas-liquid separation at the inlet of the water washing tower during subsequent water washing, easy gas blockage in the system, and in severe cases, flooding into the alkali washing process, reacting with sodium hypochlorite to generate harmful substances such as chlorine gas, resulting in serious corrosion and shutdown of the system, directly affecting safe production. Summary of the Invention

[0003] The utility model provides a low-acidity high-purity dichlorofluoroethane alkali washing system with a simple structure, which can effectively improve the alkali washing effect, prevent flooding of the water washing tower into the alkali washing tower, and improve the safety production performance.

[0004] The technical solution adopted by the utility model is as follows: A low-acidity high-purity dichlorofluoroethane alkali washing system includes two alkali washing towers and two alkali washing tanks. After the dichlorofluoroethane hydrochloric acid absorber, it is connected to the bottom of the first alkali washing tower. The bottom of the first alkali washing tower is connected to the first alkali washing tank through the first liquid outlet pump. The first alkali washing tank is connected to the upper part of the first alkali washing tower through the first alkali washing pump. The top of the first alkali washing tower is connected to the bottom of the second alkali washing tower. The bottom of the second alkali washing tower is connected to the second alkali washing tank through the second liquid outlet pump. The second alkali washing tank is connected to the upper part of the second alkali washing tower through the second alkali washing pump. The top of the second alkali washing tower is connected to the pipeline leading to the water tower. It is characterized in that: The first alkali washing pump is divided into three paths after passing through the first cooler. The first path is connected back to the first alkali washing tank through a valve. The second path is connected to the sodium hypochlorite storage tank through a valve. The third path is sent to the first condenser and then connected to the upper part of the first alkali washing tower. The cooling inlet pipe of the first cooler is connected with a flow regulating valve. Temperature sensors are arranged in the first alkali washing tank and at the outlet of the first cooler. Temperature sensors are arranged in the second alkali washing tank and at the outlet of the second alkali washing pump. After passing through the second alkali washing pump, it is divided into three paths. The first path is connected back to the second alkali washing tank through a valve. The second path is connected to the sodium hypochlorite storage tank through a valve. The third path is sent to the second condenser and then connected to the upper part of the second alkali washing tower. The above temperature sensors, flow regulating valves, and valves are connected to a controller.

[0005] Liquid level sensors are arranged in both the first alkali washing tank and the second alkali washing tank, and the liquid level sensors are connected to the controller.

[0006] The first alkali washing tank and the second alkali washing tank are connected through a communicating pipe, and a two-way pump is arranged on the communicating pipe.

[0007] The first cooler is a shell-and-tube heat exchanger.

[0008] The first and second condensers are shell-and-tube condensers.

[0009] The second caustic scrubbing pump is divided into three paths after passing through the second cooler, and the structure of the second cooler is the same as that of the first cooler.

[0010] On the pipelines through which the upper parts of the first and second caustic scrubbing towers are respectively connected via the first and second condensers, caustic scrubbing tower inlet liquid temperature sensors are provided, and the caustic scrubbing tower inlet liquid temperature sensors are connected to a controller.

[0011] The first caustic scrubbing tank is connected to the first caustic scrubbing tower via a balance pipe, and the second caustic scrubbing tank is connected to the second caustic scrubbing tower via a balance pipe.

[0012] The top of the second caustic scrubbing tower is connected to a caustic scrubbing separator and then goes to a gas holder or a water scrubbing tower.

[0013] The beneficial effects of the present utility model are as follows:

[0014] 1. After a long time, when the concentration of sodium hypochlorite in the first caustic scrubbing tank reaches the high-concentration index for sodium hypochlorite collection, after the first caustic scrubbing pump distributes and sends it to the sodium hypochlorite storage tank for collection, the second caustic scrubbing tank pumps the caustic scrubbing liquid with a low sodium hypochlorite concentration to the first caustic scrubbing tank for use through a two-way pump; it is also possible to pump the caustic liquid in the first caustic scrubbing tank to the second caustic scrubbing tank according to the required caustic concentration of the caustic scrubbing liquid in the first caustic scrubbing tower, and add water to the first caustic scrubbing tank to dilute it to the required concentration, meeting the usage requirements under multiple working conditions and overall reducing the production and usage costs.

[0015] 2. Dichloroethane is sent to the first caustic scrubbing tower after passing through the hydrochloric acid absorber. The caustic scrubbing liquid is pumped out of the first caustic scrubbing tank by the first caustic scrubbing pump. According to the temperature of the caustic scrubbing liquid detected by the temperature sensors of the first caustic scrubbing tank and the first caustic scrubbing pump, by controlling the flow regulating valve on the coolant inlet pipe of the first cooler, combined with the real-time monitoring of the temperature of the caustic liquid fed in through the caustic scrubbing tower inlet liquid temperature sensor on the pipeline where the first caustic scrubbing tower is connected via the first condenser, the temperature of the caustic scrubbing liquid is controlled at 10 - 30 °C, ensuring the stability of the caustic scrubbing liquid temperature, improving the caustic scrubbing efficiency, reducing the acid content of the product, and avoiding potential safety hazards in subsequent water washing.

[0016] 3. The caustic scrubbing separator serves as a gas-liquid separation buffer tank, which can effectively eliminate the risk of hydrochloric acid entering the caustic scrubbing tower in the case of liquid flooding in the water scrubbing tower, ensuring the long-term stable operation of the device.

[0017] 4. In the caustic scrubbing system of the double caustic scrubbing towers and caustic scrubbing tanks, the caustic scrubbing and acid removal requirements of the second caustic scrubbing tower are relatively lower than those of the first caustic scrubbing tower. The second caustic scrubbing tower can adopt a temperature control similar to that of the first caustic scrubbing tower, which can better meet the requirements for the acidity level of dichloroethane products to be undetected. Description of the Drawings

[0018] Figure 1 It is a schematic structural diagram of the present utility model;

[0019] In the figure: the crude difluorochloroethane gas pipe 1, the hydrochloric acid absorber 2, the first alkali washing tower 3, the first liquid discharge pump 4, the balance pipe 5, the first alkali washing tank 6, the first alkali washing tank temperature sensor 7, the first alkali washing pump 8, the cooler 9, the flow regulating valve 10, the first circulation temperature sensor 11, the sodium hypochlorite storage tank 12, the first condenser 13, the first alkali washing tower inlet liquid temperature sensor 14, the second alkali washing tower 15, the second liquid discharge pump 16, the second alkali washing tank 17, the second alkali washing tank temperature sensor 18, the second alkali washing pump 19, the second circulation temperature sensor 20, the second condenser 21, the second alkali washing tower inlet liquid temperature sensor 22, the alkali liquid separator 23, the connecting pipe 24, the double-suction pump 25, and the controller 26. Specific embodiments

[0020] The following is further described with reference to the accompanying drawings.

[0021] Figure 1 As shown: a low-acidity high-purity difluorochloroethane alkali washing system, including the first alkali washing tower 3, the first liquid discharge pump 4, the balance pipe 5, the first alkali washing tank 6, the first alkali washing tank temperature sensor 7, the first alkali washing pump 8, the cooler 9, the flow regulating valve 10, the first circulation temperature sensor 11, the sodium hypochlorite storage tank 12, the first condenser 13, the first alkali washing tower inlet liquid temperature sensor 14, the second alkali washing tower 15, the second liquid discharge pump 16, the second alkali washing tank 17, the second alkali washing tank temperature sensor 18, the second alkali washing pump 19, the second circulation temperature sensor 20, the second condenser 21, the second alkali washing tower inlet liquid temperature sensor 22, the alkali liquid separator 23, the connecting pipe 24, the double-suction pump 25, and the controller 26.

[0022] The crude difluorochloroethane gas pipe 1 is connected to the bottom of the first alkali washing tower 3 after passing through the hydrochloric acid absorber 2. The bottom of the first alkali washing tower 3 is connected to the first alkali washing tank 6 through the first liquid discharge pump 4. The first alkali washing tank 6 is connected to the bottom of the first alkali washing tower through the balance pipe 5. The bottom of the first alkali washing tank 6 is connected to the first alkali washing pump 8. The first alkali washing pump 8 is divided into three paths after passing through the cooler 9 and the first circulation temperature sensor 11. The first path is connected back to the first alkali washing tank 6 through a valve. The second path is connected to the sodium hypochlorite storage tank 12 through a valve. The third path is sent to the first condenser 13 through a valve. The first condenser 13 is connected to the upper part of the first alkali washing tower 3 through a pipeline with the first alkali washing tower inlet liquid temperature sensor 14. The cooling inlet pipe of the cooler 9 is connected with the flow regulating valve 10. The first alkali washing tank 6 is provided with the first alkali washing tank temperature sensor 7. The first liquid discharge pump 4, the first alkali washing tank temperature sensor 7, the first alkali washing pump 8, the flow regulating valve 10, the first circulation temperature sensor 11, the first alkali washing tower inlet liquid temperature sensor 14, and the above valves are all connected to the controller 26.

[0023] The top of the first caustic scrubber 3 is connected to the bottom of the second caustic scrubber 15. The bottom of the second caustic scrubber 15 is connected to the second caustic scrubbing tank 17 via the second liquid outlet pump 16. The second caustic scrubbing tank 17 is connected to the bottom of the second caustic scrubber via a balance pipe. The bottom of the second caustic scrubbing tank 17 is connected to the second caustic scrubbing pump 19 and the second circulation temperature sensor 20, and then divides into three paths. The first path is connected back to the second caustic scrubbing tank 17 via a valve, the second path is connected to the sodium hypochlorite storage tank 12 via a valve, and the third path is sent to the second condenser 21 via a valve. The second condenser is connected to the upper part of the second caustic scrubber 15 via a pipeline with the second caustic scrubber inlet liquid temperature sensor 22. The second caustic scrubbing tank temperature sensor 18 is arranged in the second caustic scrubbing tank 17. The second liquid outlet pump 16, the second caustic scrubbing tank temperature sensor 18, the second caustic scrubbing pump 19, the flow regulating valve 10, the second circulation temperature sensor 20, the second caustic scrubber inlet liquid temperature sensor 22 and the above valves are all connected to the controller 26. The top of the second caustic scrubber 15 is connected to the caustic liquid separator 23.

[0024] In this embodiment, the first caustic scrubbing tank 6 and the second caustic scrubbing tank 17 are connected via a connecting pipe 24, and a two-way pump 25 is arranged on the connecting pipe. The two-way pump 25 is connected to the controller 26.

[0025] Based on this embodiment, liquid level sensors can also be arranged in both the first caustic scrubbing tank and the second caustic scrubbing tank, and the liquid level sensors are connected to the controller.

[0026] Based on this embodiment, after the caustic scrubbing separator, it can be selectively sent to the gas holder or the water scrubber.

[0027] The temperature sensors in the drawings of this embodiment do not represent the positions on the relative structures.

[0028] The drawings of this embodiment only show the connection relationship between the caustic scrubbing tank and the caustic scrubber, and do not limit the relationship between the position and height of the caustic scrubbing tank and the position and height of the caustic scrubber.

Claims

1. A low-acidity high-purity dichlorofluoroethane caustic washing system, comprising two caustic washing towers and two caustic washing tanks. After the dichlorofluoroethane hydrochloric acid absorber, it is connected to the bottom of the first caustic washing tower. The bottom of the first caustic washing tower is connected to the first caustic washing tank via the first liquid outlet pump. The first caustic washing tank is connected to the upper part of the first caustic washing tower via the first caustic washing pump. The top of the first caustic washing tower is connected to the bottom of the second caustic washing tower. The bottom of the second caustic washing tower is connected to the second caustic washing tank via the second liquid outlet pump. The second caustic washing tank is connected to the upper part of the second caustic washing tower via the second caustic washing pump. The top of the second caustic washing tower is connected to the pipeline leading to the water supply tower. It is characterized in that: The first caustic scrubbing pump is divided into three paths after passing through the first cooler. The first path is connected back to the first caustic scrubbing tank through a valve, the second path is connected to the sodium hypochlorite storage tank through a valve, and the third path is sent to the first condenser and then connected to the upper part of the first caustic scrubbing tower. The cooling inlet pipe of the first cooler is connected with a flow regulating valve, and temperature sensors are arranged in the first caustic scrubbing tank and at the outlet of the first cooler; Temperature sensors are arranged in the second caustic scrubbing tank and at the outlet of the second caustic scrubbing pump. The second caustic scrubbing pump is divided into three paths after passing through the second caustic scrubbing pump. The first path is connected back to the second caustic scrubbing tank through a valve, the second path is connected to the sodium hypochlorite storage tank through a valve, and the third path is sent to the second condenser and then connected to the upper part of the second caustic scrubbing tower; The above temperature sensors, flow regulating valves, and valves are connected to the controller.

2. The caustic washing system for low-acidity high-purity dichlorofluoroethane according to claim 1, wherein: Level sensors are arranged in both the first caustic scrubbing tank and the second caustic scrubbing tank, and the level sensors are connected to the controller.

3. A caustic washing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, characterized in that: The first caustic scrubbing tank and the second caustic scrubbing tank are connected through a connecting pipe, and a two-way pump is arranged on the connecting pipe.

4. The caustic washing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, wherein: The first cooler is a shell and tube heat exchanger.

5. The caustic washing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, characterized in that: The first and second condensers are double pipe condensers.

6. The caustic washing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, characterized in that: The second caustic scrubbing pump is divided into three paths after passing through the second cooler, and the structure of the second cooler is the same as that of the first cooler.

7. A caustic washing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, characterized in that: Caustic scrubbing tower inlet temperature sensors are arranged on the pipelines through which the upper parts of the first and second caustic scrubbing towers are connected through the first and second condensers respectively, and the caustic scrubbing tower inlet temperature sensors are connected to the controller.

8. The caustic washing system for low-acidity high-purity dichlorofluoroethane according to claim 1, characterized in that: The first caustic scrubbing tank is connected to the first caustic scrubbing tower through a balance pipe, and the second caustic scrubbing tank is connected to the second caustic scrubbing tower through a balance pipe.

9. The caustic scrubbing system for low-acidity high-purity 1,1-dichloro-1-fluoroethane according to claim 1, characterized in that: The top of the second caustic scrubbing tower is connected to a caustic scrubbing separator and then goes to the gas holder or the water washing tower.

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