Vinyl chloride monomer dehydration device

Abstract

The utility model aims to provide a vinyl chloride monomer dehydration device, which is characterized in that a by-pass pipe is arranged on a vinyl chloride VCM monomer conveying pipeline, and the vinyl chloride VCM monomer sequentially enters a cooler, a prefilter, a coalescer and a heater through the by-pass pipe and then returns to the conveying pipeline to complete dehydration. According to the utility model, the removal of water in the VCM monomer is realized, the problem of system blockage is solved, and the product quality and the long-period stable operation of the system are ensured.

Description

Technical Field

[0001] The utility model relates to the field of vinyl chloride dehydration, in particular to a vinyl chloride monomer dehydration device. Background Art

[0002] Vinyl chloride, also known as vinyl chloride monomer (VCM), is specifically used as a precursor for PVC. Generally, in the production process of vinyl chloride monomer by the calcium carbide method, due to the full contact between water and crude vinyl chloride gas during the water washing and alkali washing processes, water molecules are easily drawn into the post-system, resulting in hydrolysis reactions, producing a large amount of acidic substances, and causing varying degrees of corrosion and damage to steel equipment. At the same time, the iron ions generated will directly affect the resin quality of PVC, prompting oxygen to react with vinyl chloride monomer to produce more peroxides. This peroxide can both repeat the above-mentioned hydrolysis process and initiate the polymerization of vinyl chloride to produce polyvinyl chloride with a lower degree of polymerization.

[0003] Due to the above-mentioned special properties of vinyl chloride (VCM) monomer, excessive water content in vinyl chloride monomer will cause an increase in self-polymerization in the low-boiling tower and the low-boiling tower reboiler heat exchange tubes, causing system blockage; at the same time, there are many solid impurities in the system, and the catalyst with water as the carrier has many impurities, which will seriously affect the product quality. Therefore, the removal of water in VCM monomer is the key to ensuring the stable operation of the device and the quality of the product. Utility Model Content

[0004] The utility model aims to provide a vinyl chloride monomer dehydration device, which realizes the removal of water in VCM monomer, solves the problem of system blockage, and ensures product quality and long-term stable operation of the system.

[0005] The technical solution adopted by the utility model to solve the above problems is as follows:

[0006] A vinyl chloride monomer dehydration device, characterized in that it comprises a cooler, a pre-filter, a coalescer 3, and a heater;

[0007] The upper part of the cooler is connected to the vinyl chloride monomer delivery pipeline through a bypass pipe, and the lower part is connected to the upper part of the pre-filter through a pipeline. The pipeline before entering the pre-filter is connected to the vinyl chloride monomer delivery pipeline through a bypass pipe; if the pre-filter and the subsequent equipment need to be repaired, the VCM monomer enters the vinyl chloride monomer delivery pipeline through the bypass pipe 6, which does not affect the production demand; the cooler is also provided with a cooling water inlet and outlet pipeline, and the cooling water is used as a coolant to cool the vinyl chloride monomer. The cooled vinyl chloride monomer enters the pre-filter through the pipeline;

[0008] The pre-filter is connected in parallel with one for use and one for standby. The bottom of the pre-filter is connected to the external water pipe through a pipeline, and the lower part of the pre-filter is connected to one side of the upper part of the coalescer through a pipeline; the other side of the upper part of the coalescer is connected to the vinyl chloride monomer delivery pipeline and the bottom of the heater through a bypass pipe.

[0009] The upper part of the heater is connected to the vinyl chloride monomer delivery pipeline through a bypass pipe. The heater is also provided with hot water inlet and outlet pipes. The hot water is used as the heat source to heat the vinyl chloride monomer material. The heated material is transported to the back-end process flow through the delivery pipeline.

[0010] Furthermore, a water separation bag is arranged at the bottom of the coalescer, and the water separation bag is connected to an external water pipe through a pipeline.

[0011] Furthermore, the coalescer is a horizontal phase separation device, in which a demulsification unit, a coalescing unit and a separation unit are arranged from left to right, and each unit is filled with a filter medium, and the pore size of the filter medium becomes smaller in sequence.

[0012] The utility model has the following beneficial effects

[0013] 1. Cool the material through cooler 1 to convert the dissolved water in the system into free water as much as possible to meet the process design requirements.

[0014] 2. The pre-filter 2 is arranged at the front end of the coalescer 3 to separate and filter solid particles, effectively preventing solid particles from clogging the coalescer 3 and causing a decrease in the separation efficiency of the coalescer 3. The pre-filter 2 can make the performance of the entire coalescing system better, the operation more stable, and the maintenance cost lower.

[0015] 3. The coalescer 3 is a horizontal phase separation device, which is equipped with a demulsification unit, a coalescing unit and a separation unit. Each unit is filled with a filter medium, and the pore size of the filter medium increases layer by layer. When the fluid flows through the filter medium, small droplets compete to pass through the openings and gradually gather into large droplets. These large droplets are easier to separate from the continuous phase fluid and settle to the bottom of the coalescer by their own gravity, thereby achieving the purpose of dehydrating vinyl chloride.

[0016] 4. Heater 4 is arranged after coalescer 3. The low-temperature material after being treated by coalescer 3 may have a certain influence on the operating performance of the low-boiling tower. Therefore, heater 4 is arranged after coalescer 3 to raise the material temperature to about 40°C to meet the process operation requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a vinyl chloride monomer dehydration device of the utility model;

[0018] Figure 2 It is a schematic diagram of the structure of the coalescer;

[0019] Description of the accompanying drawings: cooler 1, pre-filter 2, coalescer 3, heater 4, conveying pipeline 5, bypass pipe 6, water distribution bag 7. DETAILED DESCRIPTION

[0020] The utility model is described in detail below with reference to the accompanying drawings:

[0021] like Figure 1 As shown, a vinyl chloride monomer dehydration device adopts a "variable temperature + coalescence" combined process design route. A bypass pipe 6 is provided on the vinyl chloride VCM monomer conveying pipeline 5. The monomer then passes through the bypass pipe 6 in sequence into the cooler 1, the pre-filter 2, the coalescer 3, the heater 4 and then returns to the conveying pipeline 5 to complete the dehydration purpose.

[0022] The vinyl chloride monomer enters the cooler 1 through the feed port of the cooler 1. The function of the cooler 1 is to cool the material under normal production conditions of the system and convert the dissolved water in the system into free water as much as possible to meet the process design requirements. The cooler 1 is a heat exchange device, which is provided with a VCM monomer inlet and outlet and a cooling water inlet and outlet. The cooling water is used as a coolant to cool the vinyl chloride monomer. The cooled vinyl chloride monomer enters the pre-filter 2 through the VCM monomer outlet of the cooler 1;

[0023] The pre-filter 2 is arranged at the front end of the coalescer 3 to separate and filter solid particles, effectively preventing solid particles from clogging the coalescer 3 and causing the separation efficiency of the coalescer 3 to decrease. The pre-filter 2 can make the performance of the entire coalescing system better, the operation more stable, and the maintenance cost lower. The pre-filter 2 is a solid-liquid separation device with two units connected in parallel, one for use and one for standby. It is an inlet and outlet and a liquid discharge port, and a bypass pipe 6 is arranged before the inlet. If the pre-filter 2 and the subsequent equipment need to be repaired, the VCM monomer enters the conveying pipeline 5 through the bypass pipe 6, which does not affect the production demand, and the outlet is connected to the inlet of the coalescer 3.

[0024] like Figure 2 As shown, the coalescer 3 is a horizontal phase separation device, which is provided with a demulsification unit, a coalescing unit and a separation unit. Each unit is filled with a filter medium, and the pore size of the filter medium is gradually reduced. The demulsification unit uses the filter medium to demulsify the emulsified oil. The coalescing unit is used to convert small oil droplets into large droplets through the capillary effect, collision coalescence and wetting coalescence of the filter medium. The separation unit uses a fine filter pore size to further separate the large droplets.

[0025] When the fluid flows through the filter medium, under the action of the demulsification unit, coalescing unit and separation unit, the small droplets compete to pass through the openings and gradually gather into large droplets. These large droplets are easier to separate from the continuous phase fluid and settle to the bottom of the coalescer in the container by their own gravity, thereby achieving the purpose of VCM dehydration.

[0026] The coalescer 3 is provided with an inlet and an outlet, and a water separation bag 7 and a water separation port are provided at the lower part. The outlet is connected to the heater 4 and is connected to the conveying pipeline 5 through a bypass pipe 6 to facilitate the maintenance of the heater 4.

[0027] Heater 4 is arranged after coalescer 3. The low-temperature material after being treated by coalescer 3 may have a certain impact on the operating performance of the low-boiling tower (the destination of conveying pipeline 5). Therefore, heater 4 is arranged after coalescer 3 (i.e. before the low-boiling tower) to raise the material temperature to about 40°C to meet the process operation requirements. Heater 4 is a heat exchange device, which is provided with an inlet and outlet and a hot water inlet and outlet. Hot water is used as a heat source to heat the VCM monomer material, and the heated material is transported to the back-end process flow through conveying pipeline 5.

[0028] The following is an explanation with specific cases:

[0029] Case 1:

[0030] In the second phase of the PVC project of a chlor-alkali company, a pre-filter 2 and a coalescer 3 were installed on the VCM monomer delivery pipeline, with a processing capacity of 14 to 18 m 3 / h, the average daily drainage volume is about 1550kg, the dehydration rate is up to 91.17%, the water content in vinyl chloride monomer and the content of resin powder are significantly reduced, and other quality indicators such as the whiteness of the finished resin are significantly improved.

[0031] Case 2:

[0032] A new 400,000 tons / year vinyl chloride project of a chlor-alkali enterprise adopts the "variable temperature + coalescence" combined process design route, with a processing capacity of 40m 3 / h, the water content of the inlet water is 3000ppm, the free water removal rate in the process material after treatment is about 99%, and the total water content is less than 750ppm.

Claims

1. A vinyl chloride monomer dehydration device, characterized in that: It comprises a cooler (1), a pre-filter (2), a coalescer (3), and a heater (4); The upper part of the cooler (1) is connected to the vinyl chloride monomer delivery pipeline (5) through a bypass pipe (6), and the lower part is connected to the upper part of the pre-filter (2) through a pipeline. The pipeline before entering the pre-filter (2) is connected to the vinyl chloride monomer delivery pipeline (5) through the bypass pipe (6); the cooler (1) is also provided with a cooling water inlet and outlet pipeline, and the cooling water is used as a coolant to cool the vinyl chloride monomer. The cooled vinyl chloride monomer enters the pre-filter (2) through the pipeline; The bottom of the pre-filter (2) is connected to an external water pipe through a pipe, and the lower part of the pre-filter (2) is connected to one side of the upper part of the coalescer (3) through a pipe; the other side of the upper part of the coalescer (3) is connected to the vinyl chloride monomer delivery pipe (5) and the bottom of the heater (4) through a bypass pipe (6); The upper part of the heater (4) is connected to the vinyl chloride monomer conveying pipeline (5) through a bypass pipe (6). The heater (4) is also provided with hot water inlet and outlet pipelines. The hot water is used as a heat source to heat the vinyl chloride monomer material. The heated material is conveyed to the back-end process flow through the conveying pipeline (5).

2. A vinyl chloride monomer dehydration device as claimed in claim 1, characterized in that: A water separation bag (7) and a water separation port are arranged at the bottom of the coalescer (3), and the water separation bag is connected to an external water pipe through a pipeline.

3. A vinyl chloride monomer dehydration device as claimed in claim 2, characterized in that: The coalescer (3) is a horizontal phase separation device, and is provided with a demulsification unit, a coalescing unit and a separation unit from left to right in sequence. Each unit is filled with a filter medium, and the pore size of the filter medium decreases in sequence.

4. A vinyl chloride monomer dehydration device as claimed in claim 1, characterized in that: The pre-filter (2) is connected in parallel with one for use and one for standby.

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