A chlorinated polyethylene process off-gas treatment system

Abstract

The application discloses a chlorinated polyethylene process tail gas treatment system and belongs to the technical field of fine chemical tail gas treatment. The system comprises a water washing tower and an alkali washing tower. The bottom of the water washing tower is connected with a water washing liquid reflux tank. The water washing liquid reflux tank is connected with the upper part of the water washing tower through a water washing liquid circulating pump. The bottom of the water washing tower is provided with an input end of device tail gas. The top of the water washing tower is connected with the lower part of the alkali washing tower. The bottom of the alkali washing tower is connected with an alkali liquid reflux tank. The alkali liquid reflux tank is connected with the upper part of the alkali washing tower through an alkali liquid circulating pump and an alkali liquid cooler. The application realizes the standard discharge of chlorinated polyethylene process tail gas.

Description

Technical Field

[0001] This utility model relates to the field of fine chemical tail gas treatment technology, and specifically to a tail gas treatment device for chlorinated polyethylene process. Background Technology

[0002] Chlorinated polyethylene (CPE) is an important downstream product of chlorine. It is an excellent impact modifier for PVC plastics and a synthetic rubber with good overall performance. It is widely used in cables, wires, hoses, rubber sheets, rubber and plastic products, sealing materials, flame-retardant conveyor belts, waterproof membranes, films, and various profiles. Currently, the most widely used CPE production processes include the acid-phase method and the aqueous-phase method. Both methods generate large amounts of tail gas containing chlorine and hydrogen chloride. This tail gas cannot be directly emitted into the atmosphere and must be treated to meet emission standards. Utility Model Content

[0003] The purpose of this invention is to provide a tail gas treatment device for chlorinated polyethylene process, which is used to treat the tail gas containing chlorine and hydrogen chloride generated during the production process of chlorinated polyethylene, thereby achieving compliant emissions.

[0004] The objective of this utility model can be achieved through the following technical solutions:

[0005] A process tail gas treatment system for chlorinated polyethylene includes a water washing tower and an alkaline washing tower. The bottom of the water washing tower is connected to a water washing liquid return tank, and the water washing liquid return tank is connected to the upper part of the water washing tower through a water washing liquid circulation pump. The bottom of the water washing tower is provided with an input end for the device tail gas.

[0006] The top of the water washing tower is connected to the bottom of the alkali washing tower, and the bottom of the alkali washing tower is connected to the alkali reflux tank. The alkali reflux tank is connected to the top of the alkali washing tower through an alkali circulation pump and an alkali cooler.

[0007] In this utility model, the washing liquid return tank is equipped with a washing liquid return tank level gauge and a fresh water input pipe, and the fresh water input pipe is equipped with a fresh water shut-off valve.

[0008] In this utility model, a pH meter for the washing liquid is installed between the washing liquid return tank and the washing liquid circulation pump.

[0009] In this utility model, a washing liquid discharge valve is provided on the wastewater discharge pipe at the outlet of the washing liquid circulation pump.

[0010] In this utility model, the alkali reflux tank is equipped with an alkali reflux tank level gauge and an input end for fresh alkali, and the input end for fresh alkali is equipped with a fresh alkali shut-off valve.

[0011] In this utility model, an alkali pH meter is installed on the pipeline connecting the alkali reflux tank and the alkali circulation pump.

[0012] In this utility model, an alkali discharge valve is provided on the waste alkali discharge pipeline of the alkali circulation pump.

[0013] In this utility model, a blower is provided at the top of the alkali washing tower, and the output end of the blower is connected to the atmosphere.

[0014] In some specific technical solutions, the content is as follows:

[0015] A tail gas treatment device for chlorinated polyethylene process includes a water washing tower, a water washing liquid return tank, a water washing liquid circulation pump, an alkali washing tower, an alkali solution return tank, an alkali solution circulation pump, an alkali solution cooler, a blower, a fresh water shut-off valve, a fresh alkali solution shut-off valve, a water washing liquid discharge valve, an alkali solution discharge valve, a water washing liquid return tank level gauge, an alkali solution return tank level gauge, a water washing liquid pH meter, and an alkali solution pH meter.

[0016] The exhaust gas from the unit enters from the bottom of the water washing tower, the top of the water washing tower is connected to the bottom of the alkali washing tower, the top of the alkali washing tower is connected to the inlet of the blower, and the outlet of the blower is vented.

[0017] The bottom of the washing tower is connected to the washing liquid return tank, the bottom of the washing liquid return tank is connected to the inlet of the washing liquid circulation pump, and the outlet of the washing liquid circulation pump is connected to the top of the washing tower.

[0018] The bottom of the alkaline washing tower is connected to the alkaline washing liquid return tank, the bottom of the alkaline washing liquid return tank is connected to the inlet of the alkaline washing liquid circulation pump, the outlet of the alkaline washing liquid circulation pump is connected to the alkaline liquid cooler, and the alkaline liquid cooler is connected to the top of the alkaline washing tower.

[0019] The pH meter for the washing solution is installed on the bottom pipeline of the washing solution return tank, the pH meter for the alkali solution is installed on the bottom pipeline of the alkali solution return tank, the level gauge for the washing solution return tank is installed in the washing solution return tank, and the level gauge for the alkali solution return tank is installed in the alkali solution return tank.

[0020] The fresh water supply line is connected to the washing solution return tank, and a fresh water shut-off valve is installed on the line. The fresh alkali supply line is connected to the alkali return tank, and a fresh alkali shut-off valve is installed on the line.

[0021] The wastewater discharge pipe is connected to the outlet of the washing liquid circulation pump, and a washing liquid discharge valve is installed on the pipe. The waste alkali discharge pipe is connected to the outlet of the alkali circulation pump, and an alkali discharge valve is installed on the pipe.

[0022] When the pH of the washing solution is low, the interlock opens the washing solution drain valve; when the level in the washing solution return tank is low, the interlock closes the washing solution drain valve and opens the fresh water shut-off valve; when the level in the washing solution return tank is high, the interlock closes the fresh water shut-off valve. Similarly, when the pH of the alkali solution is low, the interlock opens the alkali solution drain valve; when the level in the alkali solution return tank is low, the interlock closes the alkali solution drain valve and opens the fresh alkali solution shut-off valve; when the level in the alkali solution return tank is high, the interlock closes the fresh alkali solution shut-off valve.

[0023] The beneficial effects of this utility model are:

[0024] First, it achieved compliant emissions of waste gas from the chlorinated polyethylene process; second, it enabled automatic discharge and replenishment of washing liquid and alkaline washing liquid, saving human resources. Attached Figure Description

[0025] Figure 1 This is a flow chart of the tail gas treatment device for the chlorinated polyethylene process;

[0026] In the diagram, 1. Water washing tower, 2. Water washing liquid return tank, 3. Water washing liquid circulation pump, 4. Alkali washing tower, 5. Alkali solution return tank, 6. Alkali solution circulation pump, 7. Alkali solution cooler, 8. Blower, 9. Fresh water shut-off valve, 10. Fresh alkali solution shut-off valve, 11. Water washing liquid discharge valve, 12. Alkali solution discharge valve, 13. Water washing liquid return tank level gauge, 14. Alkali solution return tank level gauge, 15. Water washing liquid pH meter, 16. Alkali solution pH meter, 17. Unit tail gas, 18. Compliant tail gas, 19. Fresh water, 20. Fresh alkali solution, 21. Wastewater, 22. Waste alkali solution, 23. Circulating water supply, 24. Circulating return water. Detailed Implementation

[0027] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited thereto:

[0028] like Figure 1A tail gas treatment system for chlorinated polyethylene process includes a water washing tower 1 and an alkaline washing tower 4. The bottom of the water washing tower 1 is connected to a water washing liquid return tank 2, which is connected to the upper part of the water washing tower 1 via a water washing liquid circulation pump 3. The bottom of the water washing tower 1 is equipped with an input end for the device's tail gas. The top of the water washing tower 1 is connected to the lower part of the alkaline washing tower 4, and the bottom of the alkaline washing tower 4 is connected to an alkaline solution return tank 5, which is connected to the upper part of the alkaline washing tower 4 via an alkaline solution circulation pump 6 and an alkaline solution cooler 7. The water washing liquid return tank 2 is equipped with a water washing liquid level gauge 13 and a fresh water input pipe, and a fresh water shut-off valve 9 is installed on the fresh water input pipe. A water washing liquid pH meter 15 is installed between the water washing liquid return tank 2 and the water washing liquid circulation pump 3. A water washing liquid discharge valve 11 is installed on the wastewater discharge pipe at the outlet of the water washing liquid circulation pump 3. The alkali reflux tank 5 is equipped with an alkali reflux tank level gauge 14 and a fresh alkali inlet, with a fresh alkali shut-off valve 10 at the fresh alkali inlet. An alkali pH meter 16 is installed on the pipeline connecting the alkali reflux tank 5 and the alkali circulation pump 6. An alkali discharge valve 12 is installed on the waste alkali discharge pipeline of the alkali circulation pump 6. A blower 8 is installed at the top of the alkali washing tower 4, with its output open to the atmosphere.

[0029] The specific process is as follows:

[0030] 1) Exhaust gas absorption process

[0031] The exhaust gas 17 is introduced from the bottom of the water washing tower 1. It absorbs hydrogen chloride in the exhaust gas by contacting the water sprayed at the top of the water washing tower 1. The exhaust gas at the top of the water washing tower 1 is introduced into the bottom of the alkaline washing tower 4. It absorbs chlorine in the exhaust gas by contacting the alkaline solution sprayed at the top of the alkaline washing tower 4. The reaction equation is as follows. The exhaust gas at the top of the alkaline washing tower 4 is pressurized by the blower 8 and then released into the air.

[0032] Cl₂ + NaOH = NaCl + NaClO

[0033] 2) Circulation process of water washing solution and alkaline washing solution

[0034] The washing liquid at the bottom of the water washing tower 1 flows into the water washing liquid return tank 2, and then is sent to the top of the water washing tower 1 for reuse by the water washing liquid circulation pump 3. The alkaline washing liquid at the bottom of the alkaline washing tower 4 flows into the alkaline washing liquid return tank 5, and then is sent to the alkaline liquid cooler 7 for cooling by the alkaline washing liquid circulation pump 6, and then sent to the top of the alkaline washing tower 4 for reuse.

[0035] 3) Process for discharging and replenishing water and alkaline washing solutions

[0036] When the pH meter reading of the washing liquid is low (15), the interlocking valve 11 opens. When the level gauge reading of the washing liquid return tank is low (13), the washing liquid discharge valve 11 closes, and after a 2-second delay, the fresh water shut-off valve 9 opens to replenish fresh water (19). When the level gauge reading of the washing liquid return tank is high (13), the fresh water shut-off valve 9 closes, and water replenishment stops.

[0037] When the pH meter 16 reading is low, the alkali discharge valve 12 is opened interlocked. When the alkali return tank level gauge 14 reading is low, the alkali discharge valve 12 is closed, and after a 2-second delay, the fresh alkali shut-off valve 10 is opened to replenish fresh alkali 20. When the alkali return tank level gauge 14 reading is high, the fresh alkali shut-off valve 10 is closed, and alkali replenishment is stopped.

Claims

1. A tail gas treatment system for chlorinated polyethylene process, characterized in that, The system includes a water washing tower (1) and an alkaline washing tower (4). The bottom of the water washing tower (1) is connected to a water washing liquid return tank (2). The water washing liquid return tank (2) is connected to the upper part of the water washing tower (1) through a water washing liquid circulation pump (3). The bottom of the water washing tower (1) is provided with an input end for the device exhaust gas. The top of the water washing tower (1) is connected to the bottom of the alkali washing tower (4), and the bottom of the alkali washing tower (4) is connected to the alkali reflux tank (5). The alkali reflux tank (5) is connected to the top of the alkali washing tower (4) through the alkali circulation pump (6) and the alkali cooler (7).

2. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, The washing liquid return tank (2) is equipped with a washing liquid return tank level gauge (13) and a fresh water inlet pipe, and a fresh water shut-off valve (9) is provided on the fresh water inlet pipe.

3. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, A washing liquid pH meter (15) is installed between the washing liquid return tank (2) and the washing liquid circulation pump (3).

4. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, The wastewater discharge pipe at the outlet of the washing liquid circulation pump (3) is equipped with a washing liquid discharge valve (11).

5. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, The alkali reflux tank (5) is equipped with an alkali reflux tank level gauge (14) and a fresh alkali input terminal, and a fresh alkali shut-off valve (10) is provided on the fresh alkali input terminal.

6. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, An alkaline pH meter (16) is installed on the pipeline connecting the alkaline reflux tank (5) and the alkaline circulation pump (6).

7. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, The alkali circulation pump (6) is equipped with an alkali discharge valve (12) on the waste alkali discharge pipeline.

8. The chlorinated polyethylene process tail gas treatment system according to claim 1, characterized in that, The top of the alkaline washing tower (4) is equipped with a blower (8), and the output end of the blower (8) is connected to the atmosphere.

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