Safety filter device for front end of vinyl chloride rectification system delivery pump

Abstract

This utility model discloses a safety filtration device for the front end of the transfer pump in a vinyl chloride distillation system, belonging to the field of vinyl chloride production technology. It addresses the problem of vinyl chloride leakage during filter element replacement when crude vinyl chloride monomer enters the distillation system via the transfer pump. The device includes a monomer tank, a filter, a monomer pump, a steam coil, and a gas holder, sequentially connected to a vinyl chloride pipeline. The filter contains a filter element and a pressure transmitter is mounted on it. The steam coil is located around the filter, and the gas holder is connected to the filter via a recovery pipeline. This utility model adds a vinyl chloride replacement and recovery system to safely recover residual vinyl chloride during filter cleaning or filter element replacement, preventing leakage and significantly improving economic, safety, and environmental benefits. It features a simple structure, low installation cost, high retrofit returns, and strong practicality.

Description

Technical Field

[0001] This utility model belongs to the field of vinyl chloride production technology, specifically relating to a safety filter device used at the front end of the delivery pump of a vinyl chloride distillation system. Background Technology

[0002] In the calcium carbide-based polyvinyl chloride (PVC) production process, the distillation system uses liquid-phase feed to separate and purify vinyl chloride. A monomer transfer pump is typically installed before the distillation column to pump vinyl chloride monomer. To ensure the quality of the monomer entering the distillation system, a monomer filter is usually installed on the pipeline upstream of the pump. Its main function is to block rust and welding slag from the pipeline. Simultaneously, because a small amount of vinyl chloride monomer undergoes self-polymerization during transport, these impurities gradually accumulate in the distillation column, causing blockages in the equipment, pipelines, and trays, thus affecting the separation efficiency of the distillation system. Therefore, a filter needs to be installed before the monomer transfer pump to intercept impurities and ensure the quality of the monomer feed to the distillation system.

[0003] However, filters require regular cleaning or filter element replacement after long-term use. During routine filter element replacement, vinyl chloride leakage is common. This results in waste of monomer raw materials, leading to increased production costs. Furthermore, since vinyl chloride is a flammable, explosive, toxic, and hazardous chemical, the explosion risk posed by vinyl chloride leakage poses a potential hazard to the health of workers and the environment.

[0004] In summary, when existing vinyl chloride crude monomers enter the distillation system, there is an urgent need to configure a safe, reliable, economical, and efficient system device before the transfer pump to filter pipeline impurities and self-polymers, and to have vinyl chloride recovery and replacement functions, in order to overcome the problems mentioned in the background technology. Utility Model Content

[0005] The purpose of this invention is to provide a safety filter device for the front end of the transfer pump in a vinyl chloride distillation system, so as to solve the problem of vinyl chloride leakage when the filter element of the pipeline filter is replaced when the crude vinyl chloride monomer enters the distillation system through the transfer pump.

[0006] To solve the above problems, the technical solution of this utility model is as follows: A safety filtration device for the front end of a transfer pump in a vinyl chloride distillation system includes a unit tank, a filter, a unit pump, a steam coil, and a gas holder connected sequentially to a vinyl chloride pipeline. The filter contains a filter element and a pressure transmitter is installed on the filter. The steam coil is located on the outer periphery of the filter, and the gas holder is connected to the filter through a recovery pipeline.

[0007] Furthermore, a nitrogen pipeline with a nitrogen valve is installed on the vinyl chloride pipeline between the individual tank and the filter; a sampling pipeline with a vent valve is also installed on the filter. This facilitates nitrogen purging of the filter after the gaseous vinyl chloride is collected in the gas holder, ensuring that the vinyl chloride content is <0.4% when the filter cap is opened for filter element replacement, thus guaranteeing the safety of operators.

[0008] Furthermore, one end of the steam coil is connected to a steam pipe, which is equipped with a steam valve, and the other end of the steam coil is connected to a condensate pipe. Steam and condensate recovery lines are provided for the steam coil, and the steam valve facilitates the adjustment of steam volume to control the heating level of the filter.

[0009] Furthermore, a feed valve is installed on the vinyl chloride pipelines at both ends of the unit tank, and a feed valve is installed on the vinyl chloride pipeline between the filter and the unit pump. This allows for the opening and closing control of the filter's connection and disconnection on the vinyl chloride pipeline, facilitating independent maintenance of the filter outside the system.

[0010] The beneficial effects of this utility model are as follows: (1) This utility model uses a steam coil to heat the residual vinyl chloride in the filter, promote the volatilization of vinyl chloride, and finally collect and temporarily store it in a gas holder. The pressure transmitter monitors the pressure in the filter and indicates abnormal pressure, which makes it easier to accurately grasp the timing of filter element flushing and replacement, and also facilitates monitoring whether the vinyl chloride replacement is sufficient. In addition, it plays a role in displaying and reminding when replacing vinyl chloride with nitrogen and replacing air with nitrogen in the later stages.

[0011] (2) This utility model adds a vinyl chloride replacement and recovery system to achieve safe recovery of residual vinyl chloride during filter cleaning or filter element replacement, prevent leakage, and significantly improve economic, safety and environmental benefits. It has a simple structure, low installation cost, high retrofit benefits and strong practicality. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of a safety filter device used at the front end of a delivery pump in a vinyl chloride distillation system.

[0013] The attached diagram is labeled as follows: 1-Unit tank; 2-Filter; 3-Unit pump; 4-Filter element; 5-Steam coil; 6-Gas holder; G1-Wine chloride pipeline; G2-Steam pipeline; G3-Condensate pipeline; G4-Recovery pipeline; G5-Nitrogen pipeline; G6-Sampling pipeline; F1-Feed valve one; F2-Feed valve two; F3-Steam valve; F4-Recovery valve; F5-Nitrogen valve; F6-Vent valve; P-Pressure transmitter. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0015] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0016] Example 1 like Figure 1 As shown, a safety filtration device for the front end of a vinyl chloride distillation system transfer pump includes a unit tank 1, a filter 2, and a unit pump 3 connected in sequence to a vinyl chloride pipeline G1.

[0017] Feed valve F1 is installed on the vinyl chloride pipeline G1 at both ends of the monomer tank 1, and feed valve F2 is installed on the vinyl chloride pipeline G1 between the filter 2 and the monomer pump 3.

[0018] A pressure transmitter P is installed at the top of filter 2. Filter 2 contains a removable filter element 4, typically with a 50-mesh pore size. A steam coil 5 is located around filter 2. One end of the steam coil 5 is connected to a steam pipe G2, which is equipped with a steam valve F3. The other end of the steam coil 5 is connected to a condensate pipe G3. This steam / water path... Figure 1 The blue area indicates this. Filter 2 also has two additional air paths, one of which connects to the air tank 6 via a recovery pipe G4. A recovery valve F4 is installed on the recovery pipe G4. This air path... Figure 1 The other gas path, indicated by purple, achieves safe venting through sampling pipe G6. Sampling pipe G6 is equipped with a vent valve F6. This gas path... Figure 1 The middle part is represented by green.

[0019] A nitrogen pipeline G5 is installed on the vinyl chloride pipeline G1 between the individual tank 1 and the filter 2. A nitrogen valve F5 is installed on the nitrogen pipeline G5. This nitrogen pipeline... Figure 1 The center is indicated in red.

[0020] The working process of this utility model is as follows: Under normal working conditions: Vinyl chloride monomer exits from monomer tank 1, enters filter 2 through vinyl chloride pipeline G1, and is filtered by filter element 4. Various impurities are intercepted in filter element 4. The purified vinyl chloride monomer is pumped to the distillation system by monomer pump 3.

[0021] In abnormal working conditions: When the pressure transmitter P increases and exceeds the set range, an alarm will sound, indicating that the filter element needs to be flushed or replaced. In this case, the pumping of vinyl chloride monomer needs to be stopped or the filtration of vinyl chloride monomer needs to be switched to a standby filtration unit, leaving the filtration unit that needs to be flushed or replaced idle.

[0022] That is, the feed valve 1 F1 and feed valve 2 F2 are shut off, the steam valve F3 and the recovery valve F4 are opened, and the steam pipeline G2 starts to supply steam to heat the vinyl chloride remaining in the filter 2, causing it to undergo a phase change. Finally, the gaseous vinyl chloride is collected in the gas holder 6 through the recovery pipeline G4, waiting to be recycled.

[0023] Once the pressure transmitter P reading stabilizes (close to 0 or 0) and stops changing, close the steam valve F3 and open the nitrogen valve F5 and recovery valve F4 to purge the residual vinyl chloride in filter 2 with nitrogen. The nitrogen discharged from the filter and the residual vinyl chloride continue to be sent to the gas holder 6. After 10 minutes, open the vent valve F6 and take a sample on the sampling pipeline G6 for monitoring. When the vinyl chloride content is <0.4%, the purging is qualified. Close the nitrogen valve F5, and the maintenance worker can open the cover on filter 2 to clean and replace filter element 4. When the monitoring sampling result shows that the vinyl chloride content is ≥0.4%, close the vent valve F6 and repeat the above nitrogen purging operation to continue purging until the sampling is qualified.

[0024] After rinsing and cleaning the filter element or replacing the filter element, tighten the top cover of filter 2, open the nitrogen valve F5, and continue air replacement. Observe the pressure gauge P to show a pressure of 0.5 MPa. Use soapy water to test for leaks in the top cover of filter 2. After the leak test is completed, open the vent valve F6 on the top of filter 2 to release pressure and take a sample. It can be put into use only after the oxygen content is ≤0.2%. If the oxygen content does not meet the standard, it is necessary to continue replacement until the replacement is qualified.

[0025] Finally, close the nitrogen valve F5 and the vent valve F6, open the feed valve one F1 and the feed valve two F2, start the monomer pump 3, and the vinyl chloride monomer pumping system resumes operation.

[0026] It should be noted that the filters, filter elements, pumps, and valves used in this embodiment are all commercially available products. The specific selection and calculation methods are determined based on production capacity and budget. As long as production personnel can use them according to the product operating instructions, it will not affect the sufficiency of the disclosure of this utility model, and will not be elaborated further.

Claims

1. A safety filtration device for the front end of a transfer pump in a vinyl chloride distillation system, the device comprising a unit tank (1), a filter (2), and a unit pump (3) sequentially connected to a vinyl chloride pipeline (G1), wherein the filter (2) is provided with a filter element (4), characterized in that: The device also includes a steam coil (5), a gas holder (6), and a pressure transmitter (P). The steam coil (5) is located on the outer periphery of the filter (2), the gas holder (6) is connected to the filter (2) through a recovery pipe (G4), and the pressure transmitter (P) is located on the filter (2).

2. The safety filter device for the front end of the delivery pump in a vinyl chloride distillation system as described in claim 1, characterized in that: A nitrogen pipeline (G5) is provided on the vinyl chloride pipeline (G1) between the unit tank (1) and the filter (2), and a nitrogen valve (F5) is provided on the nitrogen pipeline (G5); a sampling pipeline (G6) is also provided on the filter (2), and a vent valve (F6) is provided on the sampling pipeline (G6).

3. A safety filter device for the front end of a delivery pump in a vinyl chloride distillation system as described in claim 1 or 2, characterized in that: One end of the steam coil (5) is connected to a steam pipe (G2), and a steam valve (F3) is provided on the steam pipe (G2). The other end of the steam coil (5) is connected to a condensate pipe (G3).

4. The safety filter device for the front end of the delivery pump in a vinyl chloride distillation system as described in claim 1, characterized in that: Feed valve one (F1) is provided on the vinyl chloride pipeline (G1) at both ends of the unit tank (1), and feed valve two (F2) is provided on the vinyl chloride pipeline (G1) between the filter (2) and the unit pump (3).

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