A ph adjustment system for a polymerization recovery system

Abstract

The utility model discloses a kind of PH value adjusting systems for polymerization recovery system;The system includes lye storage tank, lye delivery pump, recovered vinyl chloride primary cooler, lye storage tank and lye delivery pump are connected by first pipeline, first pipeline is connected with first hand valve, recovered vinyl chloride primary cooler is connected with vinyl chloride gas phase pipeline, lye delivery pump and vinyl chloride gas phase pipeline are connected by second pipeline, first valve group, glass sight glass, second hand valve are sequentially and interval connected along the delivery direction of second pipeline, first branch pipeline is connected on the second pipeline between lye delivery pump and first valve group, first branch pipeline is communicated with lye storage tank top, second valve group is connected on first branch pipeline, characterized in that, third hand valve is connected on the pipeline between glass sight glass and second hand valve, pipeline purging device is connected on the second pipeline between third hand valve and second hand valve.The system can realize the effective emptying of lye delivery pipeline.

Description

Technical Field

[0001] This utility model relates to the production and processing of polyvinyl chloride, specifically to a pH adjustment system for a polymerization and recovery system. Background Technology

[0002] Existing technologies disclose methods for introducing alkali solution into the vinyl chloride gas phase pipeline via an alkali storage tank to adjust the pH value of the liquid vinyl chloride in the cooler. For example, a self-regulating pH adjustment device for a polymerization recovery system, disclosed in CN223366923U, employs this technology. While the one-way valve 17 in this system prevents vinyl chloride gas backflow, it causes alkali solution to remain in the pipeline, increasing the risk of pipeline corrosion and leakage, and preventing the alkali solution from being completely emptied. Utility Model Content

[0003] The purpose of this invention is to provide a pH adjustment system for a polymerization recovery system, which solves the technical problem that the alkali pipeline cannot be effectively emptied in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows.

[0005] A pH adjustment system for a polymerization recovery system includes an alkali storage tank, an alkali delivery pump, and a primary cooler for recovering vinyl chloride. The alkali storage tank and the alkali delivery pump are connected by a first pipeline, on which a first manual valve is connected. The primary cooler for recovering vinyl chloride is connected to a vinyl chloride gas phase pipeline. The alkali delivery pump and the vinyl chloride gas phase pipeline are connected by a second pipeline. Along the delivery direction of the second pipeline, a first valve group, a glass sight glass, and a second manual valve are sequentially and intermittently connected. A first branch pipeline is connected to the second pipeline between the alkali delivery pump and the first valve group. The first branch pipeline is connected to the top of the alkali storage tank and a second valve group is connected to the first branch pipeline. A third manual valve is connected to the pipeline between the glass sight glass and the second manual valve. A pipeline purging device is connected to the second pipeline between the third manual valve and the second manual valve.

[0006] Furthermore, the pipeline purging device includes a second branch pipeline connected to the second pipeline, and a fourth hand valve, a gas pressure detection device, a one-way valve, a compressed air purifier, a pressure reducer, and a nitrogen storage tank connected to the pressure reducer are sequentially and intermittently connected to the second branch pipeline.

[0007] Furthermore, a third pipeline is connected between the first pipeline and the second branch pipeline between the first hand valve and the alkali delivery pump. One end of the third pipeline is connected to the second branch pipeline between the fourth hand valve and the gas pressure detection device. A fifth hand valve is connected to the third pipeline.

[0008] Furthermore, the first valve group includes a sixth manual valve, a first self-regulating valve, and a seventh manual valve arranged sequentially at intervals.

[0009] Furthermore, the second valve group includes an eighth manual valve, a second self-regulating valve, and a ninth manual valve arranged sequentially at intervals.

[0010] Furthermore, a gas detector is installed on the first pipeline between the second hand valve and the vinyl chloride gas phase pipeline, and the gas detector is connected to a gas alarm controller.

[0011] Compared with the prior art, the beneficial effects of this utility model are: This system improves upon the existing system by adding a pipeline purging device to purge the alkaline solution from the pipeline and fill it with inert gas. This helps protect the pipeline from alkaline leakage and reduces pipeline corrosion. The backflow of vinyl chloride gas can also be suppressed by changing and controlling the valves. Attached Figure Description

[0012] Figure 1 This is the system control diagram of this utility model.

[0013] Among them, 1-alkali storage tank; 2-alkali transfer pump; 3-vinyl chloride recovery primary cooler; 4-first manual valve; 5-vinyl chloride gas phase pipeline; 6-sixth manual valve; 7-glass sight glass; 8-second manual valve; 9-first automatic control regulating valve; 10-seventh manual valve; 11-eighth manual valve; 12-second automatic control regulating valve; 13-ninth manual valve; 14-third manual valve; 15-second branch pipeline; 16-fourth manual valve; 17-gas pressure detection device; 18-check valve; 19-compressed air purifier; 20-pressure regulator; 21-nitrogen storage tank; 22-third pipeline; 23-fifth manual valve; 24-gas detector. Detailed Implementation

[0014] The preferred embodiments of this utility model will be described below with reference to the accompanying drawings.

[0015] like Figure 1 As shown, a pH adjustment system for a polymerization recovery system is disclosed. The system includes an alkali storage tank 1, an alkali transfer pump 2, a primary cooler for recovering vinyl chloride 3, and additionally includes a pipeline purging device and adjustments to the valve components; the improvements enable the cleaning and emptying of the alkali transfer pipeline.

[0016] The existing system has the following connections: the alkali storage tank 1 and the alkali transfer pump 2 are connected via a first pipeline, which is connected to a first manual valve 4, a manual ball valve. The vinyl chloride recovery primary cooler 3 is connected to a vinyl chloride gas phase pipeline 5, which is an existing pipeline for vinyl chloride recovery. The alkali transfer pump 2 is connected to the vinyl chloride gas phase pipeline 5 via a second pipeline. Along the delivery direction of the second pipeline, a first valve group, a glass sight glass 7, and a second manual valve 8 are sequentially and intermittently connected. The first valve group controls the opening and closing of the pipeline. To facilitate maintenance and ensure valve control accuracy, the first valve group includes a sixth manual valve 6, a first self-regulating valve 9, and a seventh manual valve 10, sequentially and intermittently arranged. The sixth and seventh manual valves 6 and 10 are manual ball valves. The first self-regulating valve 9 receives control feedback through a pressure sensor, which is a remote pressure sensor connected to the first pipeline at the discharge end of the first valve group. The pressure sensor is connected to the DCS system. The glass sight glass 7 is used to observe whether the second pipeline is filled with alkali. The second manual valve 8 is a manual ball valve, installed near the vinyl chloride gas phase pipeline 5. A first branch pipe is connected to the second pipeline between the alkali transfer pump 2 and the first valve group. The first branch pipe is connected to the top of the alkali storage tank 1. The second valve group is connected to the first branch pipe. The alkali transfer pump 2 is primed using this pipeline to prevent cavitation damage to the pump body. The second valve group includes an eighth manual valve 11, a second self-regulating valve 12, and a ninth manual valve 13 arranged at intervals. The eighth manual valve 11 and the ninth manual valve 13 are both manual ball valves. The second self-regulating valve 12 is also controlled by a pressure sensor. The pressure sensor is a remote pressure sensor. The sensor is connected to the first pipeline at the liquid inlet of the first valve group or the first branch pipe at the liquid inlet of the second valve group. The pressure sensor is connected to the DCS system.

[0017] The improvement to the system is as follows: a third hand valve 14 is connected to the pipeline between the glass sight glass 7 and the second hand valve 8, and a pipeline purging device is connected to the second pipeline between the third hand valve 14 and the second hand valve 8. The third hand valve 14 is a manual ball valve. After the third hand valve 14 is closed, the pipeline purging device can be used to purge the alkali solution in the second hand valve 8 and the vinyl chloride gas phase pipeline 5. The opening and closing of the third hand valve 14 enables the normal delivery of alkali solution. At the same time, if the second hand valve 8 is closed, the pipeline purging device can be used to purge the alkali solution delivery pipeline.

[0018] The pipeline purging device includes a second branch pipeline 15 connected to the second pipeline, which is connected between the third hand valve 14 and the second hand valve 8. The pipeline purging device also includes a fourth hand valve 16, a gas pressure detection device 17, a one-way valve 18, a compressed air purifier 19, a pressure reducer 20, and a nitrogen storage tank 21 connected to the pressure reducer 20, all sequentially and intermittently connected to the second branch pipeline 15. The nitrogen storage tank 21 can be a nitrogen expansion tank or a nitrogen cylinder. The pressure reducer 20 controls the exhaust pressure of the storage tank; the compressed air purifier 19 purifies the nitrogen; the one-way valve 18 allows vinyl chloride gas to enter the nitrogen storage tank 21 in reverse; the gas pressure detection device 17 detects the gas pressure to determine if the system pressure is stable; it can be a remote gas pressure sensor that transmits the pressure data to the DCS system, or a conventional pressure gauge; the fourth hand valve 16 is a manual ball valve used to control the flow of nitrogen.

[0019] To achieve forward purging and venting of the alkali transfer pump 2, an additional control pipeline is designed. This control pipeline connects a third pipeline 22 between the first pipeline (between the first hand valve 4 and the alkali transfer pump 2) and the second branch pipeline 15. One end of the third pipeline 22 is connected to the second branch pipeline 15 between the fourth hand valve 16 and the gas pressure detection device 17. A fifth hand valve 23 is connected to the third pipeline 22, and the fifth hand valve 23 is adjacent to the first pipeline. The fifth hand valve 23 is a manual ball valve. When the alkali transfer pump 2 is a diaphragm pump, gear pump, or other pump suitable for reverse purging and venting, this line can be removed and discarded; if a centrifugal pump is used as the alkali transfer pump 2, or in other situations requiring both forward and reverse purging, this control pipeline is retained.

[0020] To enable leak detection and alarm for vinyl chloride, a gas detector 24 is installed on the first pipeline between the second valve 8 and the vinyl chloride gas phase pipeline 5. The gas detector 24 can be a PID gas detector 24. The gas detector 24 is connected to a gas alarm controller, which can be an audible and visual alarm. Both the gas detector 24 and the gas alarm controller are connected to the central control room of the DCS system.

[0021] When discharging alkali solution, first open the first hand valve 4, the eighth hand valve 11, and the ninth hand valve 13 to start the alkali solution transfer pump 2. Fill the pump body to prevent cavitation and expel gas from the pump. At this time, a self-circulation occurs between the alkali solution storage tank 1 and the alkali solution transfer pump 2, with the alkali solution flowing back to the storage tank 1. After running for a certain period, close the alkali solution transfer pump 2, the eighth hand valve 11, and the ninth hand valve 13. Then, sequentially open the sixth hand valve 6, the seventh hand valve 10, the third hand valve 14, and the second hand valve 8 to start the alkali solution transfer pump 2. The alkali solution in the storage tank 1 is pumped into the vinyl chloride gas phase pipeline 5 and enters the vinyl chloride recovery primary cooler 3 along with the vinyl chloride gas.

[0022] After completing the alkali transfer, stop the alkali transfer pump 2. First, close the third hand valve 14 while keeping the second hand valve 8 open; control the ball valve on the nitrogen storage tank 21 to open and control the pressure regulator 20 to open, adjusting the pressure of the pressure regulator to be greater than the gas transmission pressure in the vinyl chloride gas phase pipeline 5, and open the fourth hand valve 16. At this time, the discharged nitrogen will purge and empty the alkali between the second hand valve 8 and the vinyl chloride gas phase pipeline 5. After opening for a certain period of time, close the second hand valve 8 first. Then open the third hand valve 14, the eighth hand valve 11, and the ninth hand valve 13 to empty the alkali in the first branch pipeline. The discharged alkali is discharged to the alkali storage tank 1, which is equipped with an vent and a corresponding pressure relief valve. The discharged nitrogen fills the alkali storage tank 1. After purging the first branch pipeline, the first hand valve 4 can be opened. At this time, the alkali transfer pump 2 can be reverse-purged. After purging for a certain period, the first hand valve 4 is closed first, then the third hand valve 14 is closed, and finally the fourth hand valve 16 and the valve on the nitrogen storage tank 21 are closed. For safety, the sixth hand valve 6 and the seventh hand valve 10 are also closed. At this time, the entire tank is filled with nitrogen, effectively completing the purging purpose. The area of ​​the second hand valve 8 is sealed with nitrogen to further ensure safety. When forward purging of the alkali transfer pump 2 is required, the fourth hand valve 16 is kept closed, and the valves on the nitrogen storage tank 21, the pressure reducing valve, the fifth hand valve 23, the eighth hand valve 11, and the ninth hand valve 13 are opened accordingly, allowing the alkali to flow back into the alkali storage tank 1. After completing the forward purging, the ninth hand valve 13, the eighth hand valve 11, the fifth hand valve 23, the pressure reducing valve, and the valve on the nitrogen storage tank 21 are closed.

Claims

1. A pH adjustment system for a polymerization recovery system, comprising an alkali storage tank, an alkali delivery pump, and a primary cooler for recovering vinyl chloride, wherein the alkali storage tank and the alkali delivery pump are connected via a first pipeline, a first manual valve is connected to the first pipeline, a vinyl chloride gas phase pipeline is connected to the primary cooler for recovering vinyl chloride, the alkali delivery pump is connected to the vinyl chloride gas phase pipeline via a second pipeline, and a first valve group, a glass sight glass, and a second manual valve are sequentially and intermittently connected along the delivery direction of the second pipeline; a first branch pipeline is connected to the second pipeline between the alkali delivery pump and the first valve group, the first branch pipeline being connected to the top of the alkali storage tank, and a second valve group is connected to the first branch pipeline, characterized in that... A third hand valve is connected to the pipeline between the glass sight glass and the second hand valve, and a pipeline purging device is connected to the second pipeline between the third hand valve and the second hand valve.

2. The pH adjustment system as described in claim 1, characterized in that, The pipeline purging device includes a second branch pipeline connected to the second pipeline, and a fourth hand valve, a gas pressure detection device, a one-way valve, a compressed air purifier, a pressure reducer, and a nitrogen storage tank connected to the pressure reducer, which are connected in sequence at intervals on the second branch pipeline.

3. The pH adjustment system as described in claim 2, characterized in that, A third pipeline connects the first pipeline between the first hand valve and the alkali transfer pump and the second branch pipeline. One end of the third pipeline is connected to the second branch pipeline between the fourth hand valve and the gas pressure detection device. A fifth hand valve is connected to the third pipeline.

4. The pH adjustment system according to any one of claims 1 to 3, characterized in that, The first valve group includes a sixth manual valve, a first self-regulating valve, and a seventh manual valve arranged sequentially at intervals.

5. The pH adjustment system according to any one of claims 1 to 3, characterized in that, The second valve group includes an eighth manual valve, a second self-regulating valve, and a ninth manual valve arranged sequentially at intervals.

6. The pH adjustment system as described in claim 1, characterized in that, A gas detector is installed on the first pipeline between the second valve and the vinyl chloride gas phase pipeline, and the gas detector is connected to a gas alarm controller.

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