Chloroethylene monomer water removal system and method

Abstract

The application provides a vinyl chloride monomer water removal system and method. The system comprises a plurality of parallel adsorption towers, a first heat exchanger, a first condenser, a gas-liquid separator, a vacuum pump, a crude vinyl chloride storage tank and a nitrogen gas main. A total condenser is connected to the crude vinyl chloride storage tank inlet pipeline. The adsorption tower is connected to the crude vinyl chloride storage tank through a reverse liquid pipeline. The nitrogen gas main is in communication with the first heat exchanger. The adsorption tower nitrogen gas outlet is in communication with the first condenser. The first condenser is connected to the gas-liquid separator and the circulating nitrogen gas pipeline. The circulating nitrogen gas pipeline is in communication with the first and second pressurizing pumps. The method comprises a water-containing vinyl chloride gas condensation step, a vinyl chloride adsorption dehydration step and an adsorbent regeneration step. In the adsorbent regeneration step, the temperature-increased regenerated nitrogen gas is sent to a hot-blowing nitrogen gas pressurizing tank. The temperature-decreased cold-blowing nitrogen gas is sent to a cold-blowing nitrogen gas pressurizing tank. The application realizes efficient water removal of vinyl chloride monomers, stable control of system operating pressure and extension of the adsorbent service life.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of chemical and material production equipment, and particularly relates to a vinyl chloride monomer water removal system and method. BACKGROUND

[0002] In the production of polyvinyl chloride, the most important raw material is vinyl chloride (VCM), that is, by adding an initiator to vinyl chloride or by performing a polymerization reaction under the action of light or heat, a polymer obtained is polyvinyl chloride. Stable improvement of the quality and yield of polyvinyl chloride is one of the core problems most concerned in the production of all polyvinyl chloride industries. In production, the quality of vinyl chloride, whether good or bad and stable, will directly affect the polymerization reaction and the quality of polyvinyl chloride. If the purity of vinyl chloride is poor or contains more impurities, many side reactions will occur. Moreover, within the allowable reaction temperature, although the control of the polymerization temperature is good, problems or some irregularly shaped accompanying polymers may still occur due to the influence of purity or impurities, thereby seriously affecting the yield and quality of the overall polymerization reaction, and further adversely affecting the cost control.

[0003] The presence of water in vinyl chloride monomer is a major factor affecting the purity of vinyl chloride monomer. In the production of vinyl chloride or polyvinyl chloride, whether using calcium carbide method or oxychlorination method, the problem of water removal of vinyl chloride cannot be avoided.

[0004] Due to the presence of water, hydrolysis reaction of vinyl chloride peroxide occurs, producing hydrogen chloride (which becomes hydrochloric acid when meeting water), formic acid, formaldehyde and other acidic substances, which corrode steel equipment and generate iron ions, directly affecting the quality of polyvinyl chloride resin. The presence of iron ions promotes the reaction of oxygen and vinyl chloride monomer in the polymerization system to generate peroxide, which can not only hydrolyze repeatedly, but also initiate the polymerization of vinyl chloride monomer, generating polyvinyl chloride with low degree of polymerization, causing self-polymerization blockage of the vinyl chloride monomer process system of calcium carbide method, and making the self-polymerization of vinyl chloride monomer in the original pipeline and equipment more and more serious.

[0005] At present, the general methods for removing water from vinyl chloride monomer internationally include water separator gravity stratification water removal, solid alkali dryer dehydration process and temperature swing adsorption dehydration process. The water content of vinyl chloride monomer separated by the water separator gravity stratification water removal is still above 10,000 mg / Kg, the solid alkali dehydration needs to frequently switch equipment and remove waste alkali, the waste alkali is easy to cause environmental pollution, and the running cost is high in the later stage of solid alkali dehydration; and the temperature swing adsorption dehydration uses a special adsorbent which has a special selectivity difference for water in vinyl chloride monomer, the adsorbent absorbs water when the temperature is reduced, the adsorbent is heated and warmed to make the components adsorbed on the desiccant desorb and desorb from the desiccant, the adsorbent is regenerated and can be recycled. The temperature swing adsorption dehydration has high initial investment, but has low running cost, less maintainability, stable running and good dehydration effect. Therefore, the temperature swing adsorption dehydration is commonly used at present.

[0006] During the drying process, the pressure in the adsorption tower has a great influence on the dehydration effect. If the pressure is not properly controlled, it will affect the purity of the product vinyl chloride, and the influencing factors are the influence of crude vinyl chloride on the pressure in the adsorption tower during the dehydration process and the influence of the regeneration gas on the pressure in the adsorption tower during the regeneration process of the adsorbent. At present, the gas crude vinyl chloride is mostly dehydrated by temperature swing adsorption. However, there are some problems in the process, such as the difficulty in controlling the uniformity of the gas flow when the gas crude vinyl chloride passes through the drying agent, which leads to uneven stress on the surface of the adsorbent, uneven pressure distribution in the adsorption tower, and increased friction between the gas crude vinyl chloride and the adsorbent, which easily leads to increased adsorbent loss, affects the number of cycles of the adsorbent, causes resource waste, and reduces the drying efficiency of vinyl chloride. SUMMARY

[0007] The present application provides a vinyl chloride monomer water removal system and method to solve the above problems mentioned in the background art.

[0008] In one aspect, the present application provides a vinyl chloride monomer water removal system, comprising: a plurality of parallelly connected adsorption towers, a first heat exchanger, a first condenser, a gas-liquid separator, a vacuum pump, a crude vinyl chloride storage tank, and a nitrogen gas main pipe.

[0009] The crude vinyl chloride inlet of the adsorption tower is in communication with the crude vinyl chloride storage tank through a crude vinyl chloride pipeline, and the dehydration vinyl chloride outlet of the adsorption tower is in communication with the dry vinyl chloride main pipe. The inlet pipeline of the crude vinyl chloride storage tank is connected with a total condenser. The liquid phase monomer outlet at the bottom of the adsorption tower 1 is connected with the crude vinyl chloride storage tank through a liquid pouring pipeline, and a liquid pouring pump is arranged on the liquid pouring pipeline. The nitrogen gas main pipe is in communication with the first heat exchanger through a circulating pump, the nitrogen gas outlet of the first heat exchanger is in communication with the tower inlet nitrogen gas pipeline, and the tower inlet nitrogen gas pipeline outlet is in communication with the adsorption tower top gas inlet. The nitrogen gas outlet of the adsorption tower is in communication with the first condenser through a water-containing nitrogen gas pipeline, the liquid phase outlet of the first condenser is connected with the gas-liquid separator, the gas phase outlet of the first condenser is connected with the circulating nitrogen gas pipeline, and the circulating nitrogen gas pipeline is connected with the circulating pump.

[0010] The first pressurizing pump and the second pressurizing pump are also connected with the circulating nitrogen gas pipeline, the first pressurizing pump is connected with a hot nitrogen gas pressurizing tank, and the second pressurizing pump is connected with a cold nitrogen gas pressurizing tank.

[0011] The water-containing nitrogen gas pipeline is also connected with a vacuum pump, and the vacuum pump is connected with a vinyl chloride gas cabinet and the second pressurizing pump.

[0012] Optionally, the outlet of the hot nitrogen gas pressurizing tank and the outlet of the cold nitrogen gas pressurizing tank are connected with the circulating nitrogen gas pipeline.

[0013] Optionally, a nitrogen gas balance tank is also connected with the pipeline through which the vacuum pump is connected with the second pressurizing pump.

[0014] The gas outlet of the nitrogen balance tank is connected with the second pressurizing pump, and the liquid outlet of the nitrogen balance tank is connected with the liquid phase outlet of the gas-liquid separator.

[0015] Optionally, a cold-blowing nitrogen pipeline is connected between the circulating pump and the tower-entering nitrogen pipeline.

[0016] Optionally, a second heat exchanger is connected between the first heat exchanger and the circulating pump.

[0017] Both the first heat exchanger and the second heat exchanger use water vapor with a temperature of 180-200℃ as a heat medium.

[0018] Optionally, the first condenser is further connected with a second condenser in series.

[0019] The condensing medium used by the first condenser is circulating water with a temperature of 20-32℃, and the condensing medium used by the second condenser is chilled water with a temperature of 3-7℃.

[0020] Optionally, the water-containing nitrogen pipeline is further connected with a water-containing nitrogen branch pipeline.

[0021] The water-containing nitrogen branch pipeline is connected with the heat medium inlet of the second heat exchanger, and the heat medium outlet of the second heat exchanger is connected with the gas phase inlet of the first condenser.

[0022] Optionally, the output end of the vacuum pump is further connected with the total condenser.

[0023] In another aspect, the application provides a method for removing water from vinyl chloride monomer, which is applied to the above-mentioned vinyl chloride monomer water removal system and comprises the following steps:

[0024] (1) a water-containing vinyl chloride gas condensing step, in which water-containing vinyl chloride gas is sent to the total condenser for condensing to obtain liquid crude vinyl chloride monomer.

[0025] (2) a vinyl chloride adsorption dehydration step, in which the liquid crude vinyl chloride monomer is moved in the adsorption tower, and water is removed under the adsorption of the high-efficiency adsorbent bed layer in the adsorption tower to obtain dry vinyl chloride; the pressure in the adsorption tower is 0.18-0.28 Mpa.

[0026] (3) an adsorbent regeneration step, which comprises a vacuuming period in the adsorption tower, a heating period in which hot nitrogen is introduced into the adsorption tower to make the water adsorbed by the adsorbent bed layer warm up and be regenerated with the output of the hot nitrogen, a cooling period in which normal-temperature nitrogen is introduced into the adsorption tower to cool the adsorbent bed layer, a second vacuuming period in the adsorption tower, and an equilibrium pressure period in which gaseous vinyl chloride monomer is introduced into the adsorption tower to make the pressure in the adsorption tower reach the pressure of the vinyl chloride adsorption dehydration step; the pressure in the vacuuming period and the second vacuuming period is 0.05-0.07 Mpa.

[0027] The nitrogen gas output by the adsorption tower during the temperature rising regeneration period is sent to the hot nitrogen gas pressurized tank, and the nitrogen gas output by the adsorption tower during the temperature falling cold blowing period is sent to the cold nitrogen gas pressurized tank.

[0028] The temperature of the temperature rising regeneration period is 130-140 DEG C.

[0029] Optionally, when the pressure of the hot nitrogen gas pressurized tank is greater than or equal to 80% of the design pressure thereof, the nitrogen gas in the hot nitrogen gas pressurized tank is output to the circulating nitrogen gas pipeline; when the pressure of the cold nitrogen gas pressurized tank is greater than or equal to 80% of the design pressure thereof, the nitrogen gas in the cold nitrogen gas pressurized tank is output to the circulating nitrogen gas pipeline.

[0030] The vinyl chloride monomer dewatering system and method provided by the application realize efficient dewatering of vinyl chloride monomers, and have the following beneficial effects compared with the prior art:

[0031] (1) The water-containing vinyl chloride gas output from the top of the high-boiling tower is condensed by the full condenser to obtain liquid crude vinyl chloride monomer for dewatering. The liquid crude vinyl chloride monomer is convenient to control, and when the liquid crude vinyl chloride monomer contacts the high-efficiency adsorbent bed, the force on the surface of the high-efficiency adsorbent bed is balanced, the impact on the high-efficiency adsorbent bed is small, and it is also easier to control the upward speed of the liquid crude vinyl chloride monomer, thereby the residence time of the liquid crude vinyl chloride monomer in the adsorption tower can be appropriately increased, the dewatering effect is improved, liquid-phase adsorption is conducive to controlling the pressure in the adsorption tower, the entire system is stable in operation, and the wear of the high-efficiency adsorbent is less, the service life of the high-efficiency adsorbent is longer, and the waste of the high-efficiency adsorbent is reduced.

[0032] (2) Under the premise of the temperature of the condensed liquid crude vinyl chloride, the pressure in the adsorption tower during adsorption dewatering is controlled by the cooperative flow regulating valve, the first pressure sensor and the second pressure sensor, so that the high-efficiency adsorbent stably adsorbs and dewatering the water in the crude vinyl chloride under the regulated pressure, not only the pressure of the dewatering system is controlled, but also the drying efficiency of the crude vinyl chloride is improved. The nitrogen gas after temperature rising regeneration and temperature falling cold blowing is recovered by the first pressurizing pump, the second pressurizing pump, the hot nitrogen gas pressurized tank and the cold nitrogen gas pressurized tank, which can further stabilize the pressure of the monomer dewatering system and further improve the adsorption effect of the high-efficiency adsorbent on the water and impurities in the crude vinyl chloride.

[0033] (3) by setting the first pressurizing pump, the second pressurizing pump, the hot nitrogen blowing pressurizing tank and the cold nitrogen blowing pressurizing tank, the nitrogen gas after the temperature rising regeneration period is sent to the hot nitrogen blowing pressurizing tank through the first pressurizing pump for pressure storage, the nitrogen gas after the temperature lowering cold blowing period is sent to the cold nitrogen blowing pressurizing tank through the second pressurizing pump for pressure storage, and the pressure sensors are arranged in the hot nitrogen blowing pressurizing tank and the cold nitrogen blowing pressurizing tank, so that the controllability of the nitrogen gas pressure of the whole water removal system is improved, the backflow of the nitrogen gas in the nitrogen gas main pipe caused by the too small pressure in the hot nitrogen blowing pressurizing tank and / or the cold nitrogen blowing pressurizing tank is avoided, and the pressure control of the whole water removal system is more convenient, which is beneficial to the operation of the system under stable pressure. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0035] Figure 1 The structural schematic diagram of the vinyl chloride monomer water removal system provided by an embodiment of the present application is shown in the figure.

[0036] Figure 2 The structural schematic diagram of the vinyl chloride monomer water removal system provided by another embodiment of the present application is shown in the figure.

[0037] Figure 3 The structural schematic diagram of the vinyl chloride monomer water removal system provided by another embodiment of the present application is shown in the figure.

[0038] Explanation of reference signs:

[0039] 1 adsorption tower; 2 first heat exchanger; 3 first condenser; 4 gas-liquid separator; 5 vacuum pump; 6 crude vinyl chloride storage tank; 7 nitrogen main pipe; 8 nitrogen balance tank; 22 second heat exchanger; 33 second condenser; 110 crude vinyl chloride pipeline; 120 dry vinyl chloride main pipe; 130 dry vinyl chloride storage tank; 140 filter; 150 dry vinyl chloride gas pipeline; 210 tower inlet nitrogen pipeline; 310 water-containing nitrogen pipeline; 320 circulating nitrogen pipeline; 330 water-containing nitrogen branch pipeline; 510 vacuum valve; 520 nitrogen pressure relief valve; 600 monomer valve; 610 total condenser; 620 liquid pouring pipeline; 630 liquid pouring valve; 640 liquid pouring pump; 701 circulating pump; 710 first pressurizing pump; 711 first nitrogen valve; 712 second nitrogen valve; 713 third nitrogen valve; 714 fourth nitrogen valve; 715 fifth nitrogen valve; 716 sixth nitrogen valve; 717 seventh nitrogen valve; 718 eighth nitrogen valve; 720 second pressurizing pump; 730 hot-blowing nitrogen pressurizing tank; 740 cold-blowing nitrogen pressurizing tank; 750 cold-blowing nitrogen pipeline; 1101 flow regulating valve; 1102 first pressure sensor; 1103 second pressure sensor; 1104 first thermometer; 1105 second thermometer; 1106 third pressure sensor; 1107 fourth pressure sensor; 1201 outlet valve; 1202 moisture detector; 1203 gaseous vinyl chloride regulating valve. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are clearly and completely described below. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0041] Figure 1 A structure schematic diagram of a vinyl chloride monomer water removal system provided by an embodiment of the present application is shown in FIG. 1. The present application provides a vinyl chloride monomer water removal system, which comprises a plurality of parallelly connected adsorption towers 1, a first heat exchanger 2, a first condenser 3, a gas-liquid separator 4, a vacuum pump 5, a crude vinyl chloride storage tank 6, and a nitrogen main pipe 7. Figure 1 The crude vinyl chloride inlet of the adsorption tower 1 is communicated with the crude vinyl chloride storage tank 6 through a crude vinyl chloride pipeline 110, and the dehydrated vinyl chloride outlets of the adsorption tower 1 are all communicated with the dry vinyl chloride main pipe 120. A total condenser 610 is connected to the inlet pipeline of the crude vinyl chloride storage tank 6. The liquid-phase monomer outlet at the bottom of the adsorption tower 1 is connected with the crude vinyl chloride storage tank 6 through a liquid pouring pipeline 620, and a liquid pouring pump 640 is arranged on the liquid pouring pipeline 620.

[0042]

[0043] ​The nitrogen main pipe 7 is communicated with the first heat exchanger 2 through a circulating pump 701, the nitrogen outlet of the first heat exchanger 2 is communicated with a tower nitrogen pipe 210, the outlet of the tower nitrogen pipe 210 is communicated with the top gas inlet of the adsorption tower 1; the nitrogen outlet of the adsorption tower 1 is communicated with the first condenser 3 through a water-containing nitrogen pipe 310, the liquid phase outlet of the first condenser 3 is connected with a gas-liquid separator 4, the gas phase outlet of the first condenser 3 is connected with a circulating nitrogen pipe 320, and the circulating nitrogen pipe 320 is connected with the circulating pump 701.

[0044] The circulating nitrogen pipe 320 is further communicated with the first pressurizing pump 710 and the second pressurizing pump 720 respectively, the first pressurizing pump 710 is connected with a hot-blowing nitrogen pressurizing tank 730, and the second pressurizing pump 720 is connected with a cold-blowing nitrogen pressurizing tank 740.

[0045] The water-containing nitrogen pipe 310 is further connected with a vacuum pump 5, and the vacuum pump 5 is connected with a chloroethylene gas tank and the second pressurizing pump 720 respectively.

[0046] The application also provides a chloroethylene monomer water removal method, which is applied to the above-mentioned chloroethylene monomer water removal system and includes the following steps.

[0047] (1) A chloroethylene gas containing water condensing step, in which the chloroethylene gas containing water is sent to a total condenser for condensing to obtain liquid crude chloroethylene monomer.

[0048] (2) A chloroethylene adsorption dehydration step, in which the liquid crude chloroethylene monomer is moved in the adsorption tower, and water is removed under the adsorption of the high-efficiency adsorbent bed layer in the adsorption tower to obtain dry chloroethylene; the pressure in the adsorption tower is 0.18-0.28 Mpa.

[0049] (3) An adsorbent regeneration step, including a vacuum extraction period of the adsorption tower, a temperature rising regeneration period in which hot nitrogen is introduced into the adsorption tower to make the water adsorbed by the adsorbent bed layer warm up and be output with the hot nitrogen, a cooling blow period in which normal-temperature nitrogen is introduced into the adsorption tower to cool the adsorbent bed layer, a second vacuum extraction period of the adsorption tower, and an equilibrium pressure period in which gaseous chloroethylene monomer is introduced into the adsorption tower to make the pressure in the adsorption tower reach the pressure of the chloroethylene adsorption dehydration step; the pressure in the vacuum extraction period and the second vacuum extraction period is 0.05-0.07 Mpa.

[0050] The nitrogen output by the adsorption tower in the temperature rising regeneration period is sent to the hot-blowing nitrogen pressurizing tank, and the nitrogen output by the adsorption tower in the cooling blow period is sent to the cold-blowing nitrogen pressurizing tank.

[0051] The temperature in the temperature rising regeneration period is 130-140℃.

[0052] Specifically, after the synthesis of vinyl chloride monomer, a series of impurity removal steps are needed for purification, so that the purity of vinyl chloride is higher. The vinyl chloride is sequentially passed through a low-boiling tower and a high-boiling tower for rectification purification to remove impurities in the vinyl chloride. The obtained vinyl chloride still contains 600-1200 ppm of moisture, and such vinyl chloride cannot meet the polymerization reaction requirements for subsequent production of polyvinyl chloride.

[0053] (1) Water-containing vinyl chloride gas condensation: The water-containing vinyl chloride gas output from the top of the high-boiling tower is sent to a total condenser 610 for condensation, so that the vinyl chloride and the moisture therein are both condensed to obtain a mixed liquid, i.e., liquid crude vinyl chloride monomer. After condensation, the water-containing vinyl chloride gas is sent to the adsorption tower 1 for water removal. The liquid crude vinyl chloride is more convenient to control during transportation than the gaseous crude vinyl chloride. After the liquid crude vinyl chloride enters the adsorption tower 1, the liquid level is kept horizontal, and when the high-efficiency adsorbent bed layer contacts the liquid crude vinyl chloride, the surface is balanced. Compared with the uneven impact of gaseous crude vinyl chloride on the high-efficiency adsorbent bed layer, the impact of liquid crude vinyl chloride on the high-efficiency adsorbent bed layer is smaller, and it is also easier to control the upward speed of the liquid crude vinyl chloride, thereby enabling the residence time of the liquid crude vinyl chloride in the adsorption tower 1 to be appropriately increased, improving the dehydration effect. Liquid-phase adsorption is conducive to controlling the pressure in the adsorption tower 1, enabling the entire system to operate stably, while having little effect on the operation of the high-boiling tower in the previous stage. Moreover, liquid-phase adsorption causes less wear of the high-efficiency adsorbent, the high-efficiency adsorbent has a longer service life, and the waste of high-efficiency adsorbent is reduced.

[0054] The system of the present application includes two processes of water-containing vinyl chloride gas condensation, vinyl chloride adsorption dehydration, and adsorbent regeneration when in operation. The number of adsorption towers is set to multiple parallelly connected adsorption towers 1. In the present application, for example, three adsorption towers 1 are provided, and when in operation, two of the towers perform vinyl chloride adsorption dehydration operation, and the other tower performs adsorbent regeneration operation, and then the operation is sequentially switched to ensure that the vinyl chloride can be continuously dehydrated. Figure 1

[0055] ​(2) Chloroethylene adsorption dehydration: A single valve 600 is arranged on the crude chloroethylene pipeline 110 near the outlet of the crude chloroethylene storage tank 6, and the opening and closing of the single valve 600 controls the output and blockage of liquid crude chloroethylene monomer. A flow regulating valve 1101 is arranged on the crude chloroethylene pipeline 110 for regulating the flow of liquid crude chloroethylene monomer into the adsorption tower. By opening the single valve 600 and the flow regulating valve 1101, the liquid crude chloroethylene monomer in the crude chloroethylene storage tank 6 enters the adsorption tower 1 from bottom to top through the crude chloroethylene pipeline 110 to carry out the dehydration adsorption process. In this application, the crude chloroethylene storage tank 6 is used to receive the liquid crude chloroethylene monomer from the total condenser 610, and serves as a buffer for the liquid crude chloroethylene monomer, and the liquid crude chloroethylene monomer is transported to the adsorption tower 1 by the way of self-flow. The temperature of the liquid crude chloroethylene monomer is 16-25℃, and a first pressure sensor 1102 is arranged on the crude chloroethylene pipeline 110 near the inlet of the adsorption tower 1 for detecting the pressure of the liquid crude chloroethylene monomer entering the adsorption tower 1. In this application, the pressure of the liquid crude chloroethylene monomer (i.e. the pressure detected by the first pressure sensor 1102) is 0.25-0.3 MPa; to ensure stable operation of the adsorption tower 1. A second pressure sensor 1103 is arranged in the adsorption tower 1 for detecting the pressure in the adsorption tower 1, and the pressure in the adsorption tower 1 during adsorption dehydration is 0.18-0.28 MPa (i.e. the pressure detected by the second pressure sensor 1103). Under the premise of the temperature of the liquid crude chloroethylene condensed by the total condenser 610, the crude chloroethylene is transported to the adsorption tower 1 for water removal process, without the need for temperature regulation, but cooperates with the flow regulating valve 1101, the first pressure sensor 1102 and the second pressure sensor 1103 to control the pressure in the adsorption tower 1 during adsorption dehydration, so that the high-efficiency adsorbent can stably adsorb and dehydrate the water in the crude chloroethylene under the regulated pressure, not only the pressure of the water removal system is controlled, but also the drying efficiency of the crude chloroethylene is improved.

[0056] The adsorption tower 1 is provided with high-efficiency adsorbents, which are molecular sieve adsorbents such as 3A molecular sieve, 4A molecular sieve, 5A molecular sieve or 13X molecular sieve. The molecular sieve adsorbents are resistant to wear and high temperature, and have the advantage of long service life. The liquid crude vinyl chloride monomer moves upwards in the adsorption tower 1 and passes through the multiple layers of high-efficiency adsorbent bed in sequence. The high-efficiency adsorbents adsorb the water and other impurities in the liquid crude vinyl chloride monomer, and the water and other impurities stay in the pores of the high-efficiency adsorbents. The vinyl chloride continues to move to the top of the adsorption tower 1, and finally the dry vinyl chloride monomer is obtained at the top outlet of the adsorption tower 1. The dry vinyl chloride main pipe 120 is provided with an outlet valve 1201. When the outlet valve 1201 is opened, the dry vinyl chloride monomer is discharged through the dry vinyl chloride main pipe 120 and collected. The dry vinyl chloride main pipe 120 is provided with a moisture detector 1202 near the outlet of the adsorption tower 1, which is used to detect the water content in the outlet dry vinyl chloride monomer. When the moisture detector 1202 detects that the water content in the dry vinyl chloride monomer is 90-100 ppm, it indicates that the adsorption performance of the adsorbent is close to saturation state. At this time, the flow regulating valve 1101 and the outlet valve 1201 are closed, the adsorption and dehydration process of the liquid crude vinyl chloride monomer is completed, and the adsorbent is regenerated. The inner side wall of the upper part of the adsorption tower 1 is provided with a first thermometer 1104 for detecting the temperature of the upper part of the adsorption tower 1. During the adsorption and dehydration process, the temperature of the first thermometer 1104 is 16-25℃, and the water content in the obtained dry vinyl chloride is less than 100 ppm.

[0057] (3) Adsorbent regeneration: The adsorbent regeneration process is divided into six periods:

[0058] (31) Liquid output: Before the adsorbent regeneration, the residual liquid crude vinyl chloride monomer in the adsorption tower 1 is output. The liquid phase monomer outlet at the bottom of the adsorption tower 1 is connected with the crude vinyl chloride storage tank 6 through a liquid output pipeline 620, and a liquid output pump 640 is arranged on the liquid output pipeline 620. The liquid output valve 630 and the liquid output pump 640 are opened, and the residual liquid crude vinyl chloride monomer in the adsorption tower 1 is output back to the crude vinyl chloride storage tank 6 for temporary storage. When the second pressure sensor 1103 is less than or equal to the first set pressure value, it indicates that the residual liquid crude vinyl chloride monomer in the adsorption tower 1 has been mostly output, and there is only a small amount of residual liquid crude vinyl chloride monomer and a small amount of gaseous vinyl chloride. At this time, the liquid output valve 630 and the liquid output pump 640 are closed, and the vacuum pump 5 is started to vacuumize the adsorption tower 1. The first set pressure value is 0.1-0.15 MPa.

[0059] (32) Vacuumizing: Turn on the vacuum pump 5 and the vacuum valve 510 on the pipeline connecting the vacuum pump 5 and the vinyl chloride gas tank, and under the negative pressure of the vacuum pump 5, the trace amount of vinyl chloride monomer remaining in the adsorption tower 1 is transported to the vinyl chloride gas tank for temporary storage. When the second pressure sensor 1103 is less than or equal to the second set pressure value, it means that the output of the vinyl chloride monomer in the adsorption tower 1 is completed. This setting reduces the loss of vinyl chloride monomer and reduces material waste, while avoiding the mixing of vinyl chloride monomer with the subsequent regenerated gas, affecting the recycling of the regenerated gas. The second set pressure value is 0.05-0.07 MPa.

[0060] (33) Regeneration by heating: In this application, nitrogen is used as the regeneration gas. By taking advantage of the characteristics of the high-efficiency adsorbent that the adsorption effect of water decreases with temperature rise, hot nitrogen is introduced into the adsorption tower 1, so that the water and other impurities adsorbed in the pores of the high-efficiency adsorbent are desorbed and carried out of the adsorption tower 1 with the hot nitrogen.

[0061] In the technical solution of this application, the first nitrogen valve 711 is arranged on the nitrogen main pipe 7, the second nitrogen valve 712 is arranged on the tower inlet nitrogen pipeline 210, the third nitrogen valve 713 is arranged on the branch pipe connecting the tower inlet nitrogen pipeline 210 and the nitrogen inlet at the top of the adsorption tower 1, the fourth nitrogen valve 714 is arranged on the pipeline connecting the water-containing nitrogen pipeline 310 and the nitrogen outlet at the bottom of the adsorption tower 1, the fifth nitrogen valve 715 is arranged on the pipeline connecting the circulation nitrogen pipeline 320 and the first pressurizing pump 710, and the sixth nitrogen valve 716 is arranged on the pipeline connecting the circulation nitrogen pipeline 320 and the second pressurizing pump 720. The second thermometer 1105 is arranged on the inner side wall of the lower part of the adsorption tower 1 to detect the temperature of the lower part of the adsorption tower 1.

[0062] In operation, the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714, the fifth nitrogen valve 715 and the circulating pump 701 are opened. Nitrogen is output by the circulating pump 701 through the nitrogen main pipe 7, heated by the first heat exchanger 2 to obtain high-temperature nitrogen, enters the adsorption tower 1 from the top nitrogen inlet of the adsorption tower 1, and moves from top to bottom to heat the high-efficiency adsorbent bed layer layer by layer. The high-efficiency adsorbent bed layer is heated to a high temperature, the moisture and other impurities adsorbed therein are desorbed, the adsorption sites are exposed again, and the adsorption effect is restored for subsequent dehydration adsorption. The high-temperature nitrogen is output from the bottom nitrogen outlet of the adsorption tower 1. The high-temperature nitrogen moves from top to bottom, which can completely regenerate the top and bottom of the high-efficiency adsorbent bed layer and ensure the stability of the high-efficiency adsorbent bed layer and reduce wear and tear. Because the top of the high-efficiency adsorbent bed layer is the last contact site in the wet raw material liquid adsorption dehydration process, it directly affects the quality of the vinyl chloride monomer liquid flowing out of the high-efficiency adsorbent bed layer. The moisture-containing nitrogen gas pipeline 310 enters the first condenser 3 to condense the moisture and other impurities in the moisture-containing nitrogen gas into liquid to achieve gas-liquid separation. The condensed nitrogen gas is pressurized by the first pressurizing pump 710 and sent to the hot-blowing nitrogen pressurized tank 730 for storage and temporary storage. The liquid obtained by the first condenser 3 is used as a solvent in the lye preparation process, which avoids waste of water resources, reduces the load of sewage treatment, and is more environmentally friendly. During the temperature rising regeneration process, the temperature of the first thermometer 1104 (i.e., temperature rising regeneration) is 120-140°C. If the temperature is too high, the vinyl chloride will decompose to generate a small amount of hydrogen chloride, which will corrode the equipment. Preferably, the temperature of the temperature rising regeneration is 130-140°C. When the temperature detected by the second thermometer 1105 reaches 90-100°C, the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714 and the fifth nitrogen valve 715 are closed, and the temperature rising regeneration period ends.

[0063] (34) Cooling and blowing: the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714 and the sixth nitrogen valve 716 are opened. Nitrogen is output by the circulating pump 701 through the nitrogen main pipe 7, passes through the first heat exchanger 2 (at this time, the first heat exchanger 2 does not pass through the heat exchange medium, only as a channel for nitrogen), enters the adsorption tower 1 from the top nitrogen inlet of the adsorption tower 1, and moves from top to bottom to cool and cool the high-temperature nitrogen, further restoring the adsorption effect of the high-efficiency adsorbent. The nitrogen gas after cooling and blowing is output from the bottom nitrogen outlet of the adsorption tower 1. The moisture-containing nitrogen gas pipeline 310 enters the first condenser 3 for gas-liquid separation, and a small amount of water is condensed and output to the lye preparation process. The condensed nitrogen gas is pressurized by the second pressurizing pump 720 and sent to the cold-blowing nitrogen pressurized tank 740 for recovery. When the temperature detected by the second thermometer 1105 is less than or equal to 50°C, the cooling and blowing is stopped.

[0064] The nitrogen from the nitrogen main pipe 7 during the cooling and blowing is normal temperature nitrogen, and the normal temperature in the present application refers to a temperature of 15-30°C.

[0065] The nitrogen during the heating and regeneration period is sent to the hot blowing nitrogen pressurized tank 730 through the first pressurizing pump 710 for storage and recovery, and the nitrogen during the cooling and blowing period is sent to the cold blowing nitrogen pressurized tank 740 through the second pressurizing pump 720 for recovery. Compared with the prior art, the nitrogen during the heating and regeneration period and the nitrogen during the cooling and blowing period are directly fed back to the adsorption tower 1 for reuse after being separated by the first condenser 3, and the pressure of the nitrogen is difficult to accurately control in the process. In the present application, the pressure of the monomer water removal system is further stabilized, the adsorption effect of the high-efficiency adsorbent on the water and impurities in the crude chloroethylene is further improved, and the drying efficiency of the crude chloroethylene is improved.

[0066] (35) Re-vacuumizing: The nitrogen pressure relief valve 520 is arranged on the connecting pipeline between the vacuum pump 5 and the cold blowing nitrogen pressurized tank 740, the fourth nitrogen valve 714, the nitrogen pressure relief valve 520 and the vacuum pump 5 are opened, the nitrogen in the adsorption tower 1 is pumped out to the cold blowing nitrogen pressurized tank 740 for temporary storage, so that the nitrogen is discharged cleanly, and the purity of the chloroethylene and the pressure stability in the adsorption tower 1 are avoided. When the reading of the second pressure sensor 1103 is less than or equal to the third set pressure value, the re-vacuumizing is ended, and the third set pressure value is 0.05-0.07 MPa.

[0067] (36) Equalizing pressure: The gas chloroethylene monomer is introduced into the adsorption tower 1, so that the pressure in the adsorption tower 1 is at the working pressure of chloroethylene adsorption and dehydration, and preparation is made for the next adsorption and dehydration work. The dry chloroethylene gas pipeline 150 is connected to the top inlet of the adsorption tower 1 through the gas chloroethylene regulating valve 1203, the gas chloroethylene regulating valve 1203 and the outlet valve 1201 are opened, the gas chloroethylene monomer is introduced into the adsorption tower 1, and when the reading of the second pressure sensor 1103 is greater than or equal to the fourth set pressure value, the equalizing pressure is ended, and the fourth set pressure value is 0.18-0.28 MPa.

[0068] The application realizes efficient water removal of crude vinyl chloride monomer, condenses the water-containing vinyl chloride gas output from the top of the high-boiling tower through the setting of the total condenser, and obtains liquid crude vinyl chloride monomer for water removal. The liquid crude vinyl chloride monomer is convenient to control, and when the liquid crude vinyl chloride monomer contacts the high-efficiency adsorbent bed, the force on the surface of the high-efficiency adsorbent bed is balanced, the impact on the high-efficiency adsorbent bed is small, and the rising speed of the liquid crude vinyl chloride monomer is more easily controlled, thereby the residence time of the liquid crude vinyl chloride monomer in the adsorption tower can be appropriately increased, the dehydration effect is improved, liquid-phase adsorption is beneficial to the control of the pressure in the adsorption tower, the whole system operation is stable, the wear of the high-efficiency adsorbent is less by using liquid-phase adsorption, the service life of the high-efficiency adsorbent is longer, and the waste of the high-efficiency adsorbent is reduced. Under the premise of the temperature of the liquid crude vinyl chloride monomer after condensation, the pressure in the adsorption tower during adsorption and dehydration is controlled through the cooperative flow regulating valve, the first pressure sensor and the second pressure sensor, so that the high-efficiency adsorbent stably adsorbs and dehydrates the water in the crude vinyl chloride monomer under the regulated pressure, the pressure of the dehydration system is controlled, and the drying efficiency of the crude vinyl chloride monomer is improved. The nitrogen gas after the temperature rising regeneration and the temperature lowering blowing is recycled through the setting of the first pressure pump, the second pressure pump, the hot-blowing nitrogen gas pressure tank and the cold-blowing nitrogen gas pressure tank, the pressure of the monomer dehydration system can be further stabilized, and the adsorption effect of the high-efficiency adsorbent on the water and impurities in the crude vinyl chloride monomer is further improved.

[0069] Figure 2 The structure diagram of the vinyl chloride monomer dehydration system provided by another embodiment of the application is shown in FIG. 6. Figure 2 As shown in FIG. 6, the outlet of the hot-blowing nitrogen gas pressure tank 730 and the outlet of the cold-blowing nitrogen gas pressure tank 740 are connected with the circulating nitrogen gas pipeline 320.

[0070] Specifically, the outlet of the hot-blowing nitrogen gas pressure tank 730 is provided with a seventh nitrogen valve 717, the outlet of the cold-blowing nitrogen gas pressure tank 740 is provided with an eighth nitrogen valve 718, the fifth nitrogen valve 715 is opened, the nitrogen gas after the temperature rising regeneration period is pressurized by the first pressure pump 710 and sent to the hot-blowing nitrogen gas pressure tank 730 for storage and recycling, the sixth nitrogen valve 716 is opened, the nitrogen gas after the temperature lowering blowing period is pressurized by the second pressure pump 720 and sent to the cold-blowing nitrogen gas pressure tank 740 for recycling, and then the nitrogen gas is sent to the circulating nitrogen gas pipeline 320 through the hot-blowing nitrogen gas pressure tank 730 and the cold-blowing nitrogen gas pressure tank 740, and is used in the next high-efficiency adsorbent bed heating regeneration process, thereby reducing the consumption of a large amount of nitrogen gas and reducing the production cost.

[0071] Furthermore, a third pressure sensor 1106 is installed inside the hot-blown nitrogen pressurization tank 730. When the pressure value detected by the third pressure sensor 1106 is greater than or equal to 80% of the design pressure of the hot-blown nitrogen pressurization tank 730, the seventh nitrogen valve 717 is opened, outputting nitrogen from the hot-blown nitrogen pressurization tank 730 to the circulating nitrogen pipeline 320 for the heating and regeneration period of the high-efficiency adsorbent bed. A fourth pressure sensor 1107 is installed inside the cold-blown nitrogen pressurization tank 740. When the pressure value detected by the fourth pressure sensor 1107 is greater than or equal to 80% of the design pressure of the cold-blown nitrogen pressurization tank 740, the eighth nitrogen valve 718 is opened, outputting nitrogen from the cold-blown nitrogen pressurization tank 740 to the circulating nitrogen pipeline 320 for the heating and regeneration period of the high-efficiency adsorbent bed. This design improves the controllability of nitrogen, preventing nitrogen backflow in the nitrogen main pipe 7 due to insufficient pressure in the hot-blown nitrogen pressurization tank 730 and / or the cold-blown nitrogen pressurization tank 740. It also makes pressure control of the entire dehydration system more convenient, facilitating system operation under stable pressure. The design pressure of the hot-blown nitrogen pressurization tank 730 and the cold-blown nitrogen pressurization tank 740 is determined by their manufacturing materials, material thickness, and volume; therefore, the design pressure of the hot-blown nitrogen pressurization tank 730 and the cold-blown nitrogen pressurization tank 740 depends on the actual operating conditions.

[0072] Furthermore, the third pressure sensor 1106 is interlocked with the seventh nitrogen valve 717, and the fourth pressure sensor 1107 is interlocked with the eighth nitrogen valve 718.

[0073] like Figure 2 As shown, optionally, a nitrogen balance tank 8 is also connected to the pipeline connecting the vacuum pump 5 and the second pressurization pump 720.

[0074] The gas outlet of the nitrogen balance tank 8 is connected to the second pressurizing pump 720, and the liquid outlet of the nitrogen balance tank 8 is connected to the liquid phase outlet of the gas-liquid separator 4.

[0075] Specifically, the nitrogen balance tank 8 is used to buffer the nitrogen output from the adsorption tower 1 during the adsorbent regeneration process, ensuring that the entire water removal system operates under a stable pressure. The nitrogen in the nitrogen balance tank 8 inevitably carries water from the high-efficiency adsorbent bed. Therefore, the liquid phase at the bottom of the nitrogen balance tank 8, along with the liquid phase from the gas-liquid separator 4, is transported to the alkali preparation process as a solvent, thus avoiding water waste.

[0076] like Figure 2 As shown, optionally, a cold-blowing nitrogen pipeline 750 is connected between the circulating pump 701 and the nitrogen inlet pipeline 210.

[0077] Specifically, the installation of the cold-blowing nitrogen pipeline 750 makes nitrogen delivery smoother during cooling and cold blowing, which is beneficial for pressure control during nitrogen delivery.

[0078] Optionally, the first heat exchanger 2 is connected with the circulating pump 701 through a second heat exchanger 22.

[0079] The first heat exchanger 2 and the second heat exchanger 22 both use water vapor with a temperature of 180-200℃ as the heat medium.

[0080] Specifically, the first heat exchanger 2 and the second heat exchanger 22 are arranged to ensure that the water vapor heats the nitrogen gas to the required temperature, thereby ensuring the regeneration effect on the high-efficiency adsorbent.

[0081] Optionally, the first condenser 3 is further connected with a second condenser 33 in series.

[0082] The condensing medium used by the first condenser 3 is circulating water with a temperature of 20-32℃, and the condensing medium used by the second condenser 33 is chilled water with a temperature of 3-7℃.

[0083] Specifically, the nitrogen gas pipelines of the first condenser 3 and the second condenser 33 are arranged in series to ensure that the water and other impurities in the nitrogen gas are condensed and settled, thereby achieving the gas-liquid separation effect. The condensing medium introduced into the first condenser 3 is circulating water, which is used to pre-cool the nitrogen gas output by the adsorption tower 1, and the chilled water introduced into the second condenser 33 is used to further condense the nitrogen gas, thereby not only achieving the gas-liquid separation effect but also saving the cold energy utilization.

[0084] Optionally, the water-containing nitrogen gas pipeline 310 is further connected with a water-containing nitrogen gas branch pipeline 330.

[0085] The water-containing nitrogen gas branch pipeline 330 is connected with the heat medium inlet of the second heat exchanger 22, and the heat medium outlet of the second heat exchanger 22 is connected with the gas phase inlet of the first condenser 3.

[0086] Specifically, during the temperature-increasing regeneration process of the high-efficiency adsorbent bed, the high-temperature nitrogen gas output from the adsorption tower 1 is first introduced into the second heat exchanger 22 through the water-containing nitrogen gas branch pipeline 330, and exchanges heat with the nitrogen gas passing through the second heat exchanger 22. After the temperature of the nitrogen gas is increased, the nitrogen gas continues to enter the first heat exchanger 2 to exchange heat with the water vapor again. The high-temperature nitrogen gas output from the second heat exchanger 22 is introduced into the first condenser 3 to be cooled and condensed. Such an arrangement not only reduces the use of water vapor and condensing medium, reduces the consumption of heat and cold energy, but also utilizes the heat of the high-temperature nitrogen gas output from the adsorption tower 1.

[0087] Figure 3 The structure schematic diagram of the vinyl chloride monomer water removal system provided by another embodiment of the present application is shown in Figure 3 Optionally, the output end of the vacuum pump 5 is further connected with a full condenser 610.

[0088] Specifically, the pipeline connecting the vacuum pump 5 and the vinyl chloride gas tank is also connected to the total condenser 610, and the vinyl chloride extracted during the vacuum extraction period in the high-efficiency adsorbent bed regeneration process is condensed into liquid through the total condenser 610, thereby avoiding the consumption of vinyl chloride.

[0089] Optionally, the output end of the dry vinyl chloride main pipe 120 is in communication with a dry vinyl chloride storage tank 130.

[0090] The inlet of the dry vinyl chloride storage tank 130 is also provided with a filter 140.

[0091] Specifically, a small amount of high-efficiency adsorbent powder may be entrained in the dry vinyl chloride after water removal, and the dry vinyl chloride is filtered through the filter 140 before being transported to the dry vinyl chloride storage tank 130 for storage, thereby further improving the purity of the vinyl chloride.

[0092] Optionally, the adsorption tower 1 is a vertical adsorption tower.

[0093] Specifically, the vertical adsorption tower is used in the present application, and multiple layers of high-efficiency adsorbent bed can be provided, which has high adsorption efficiency, is compact in structure, occupies small area, and is simple and convenient to maintain and manage.

[0094] It should be noted that in the technical solution of the present application, the number of adsorption towers, heat exchangers and condensers is set according to the actual working condition, and the number is not limited in the drawings of the present application. The system of the present application can also automatically control the vinyl chloride water removal process through the connection controller, thereby reducing the labor intensity.

[0095] The technical solution of the present application will be described in detail below with specific examples.

[0096] The vinyl chloride monomer water removal system and method in the present embodiment has the following operation process during specific work:

[0097] (1) Water-containing vinyl chloride gas condensation: The water-containing vinyl chloride gas output from the top of the high-boiling tower is transported to the total condenser 610 for condensation, so that the vinyl chloride and the water therein are both condensed, and a mixed liquid, i.e., liquid crude vinyl chloride monomer, is obtained.

[0098] In the present embodiment, the number of adsorption towers is set to three parallelly connected adsorption towers 1, and during work, two of the towers perform vinyl chloride adsorption and dehydration operation, and the other tower performs adsorbent regeneration operation, and then the work is switched in turn to ensure that the vinyl chloride can be continuously dehydrated. The adsorption tower 1 in the present embodiment is a vertical adsorption tower.

[0099] (2) Chloroethylene adsorption dehydration: open the flow regulating valve 1101, and the liquid crude chloroethylene monomer in the crude chloroethylene storage tank 6 is moved into the adsorption tower 1 from bottom to top through the crude chloroethylene pipeline 110 to perform the dehydration adsorption process. The temperature of the liquid crude chloroethylene monomer is 16-25°C, and the first pressure sensor 1102 is used to detect the pressure of the liquid crude chloroethylene monomer entering the adsorption tower 1. In this embodiment, the pressure of the liquid crude chloroethylene monomer (i.e. the pressure detected by the first pressure sensor 1102) is 0.25-0.3 MPa. The second pressure sensor 1103 is arranged in the adsorption tower 1, and the pressure in the adsorption tower 1 during the adsorption dehydration is 0.18-0.28 MPa (i.e. the pressure detected by the second pressure sensor 1103). Without temperature regulation, the temperature of the liquid crude chloroethylene after condensation is regulated, and the pressure in the adsorption tower during the adsorption dehydration is controlled in cooperation with the flow regulating valve 1101, the first pressure sensor and the second pressure sensor, so that the high-efficiency adsorbent can stably adsorb and dehydrate the water in the crude chloroethylene at the regulated pressure.

[0100] The adsorption tower 1 is provided with a high-efficiency adsorbent such as 3A molecular sieve, 4A molecular sieve, 5A molecular sieve or 13X molecular sieve. The liquid crude chloroethylene monomer moves in the adsorption tower 1 from bottom to top, and sequentially passes through multiple layers of high-efficiency adsorbent bed. The high-efficiency adsorbent adsorbs the water and other impurities in the liquid crude chloroethylene monomer, and the water and other impurities stay in the pores of the high-efficiency adsorbent. The chloroethylene continues to move to the top of the adsorption tower 1, and finally the dry chloroethylene monomer is obtained at the top outlet of the adsorption tower 1. The outlet valve 1201 is opened, and the dry chloroethylene monomer is filtered through the filter 140, and then discharged through the dry chloroethylene main pipeline 120 and collected in the dry chloroethylene storage tank 130. The moisture detector 1202 is arranged near the position of the dry chloroethylene main pipeline 120 close to the outlet of the adsorption tower 1. When the moisture detector 1202 detects that the dry chloroethylene monomer contains 90-100 ppm of water, it indicates that the adsorption performance of the adsorbent is close to the saturation state. At this time, the flow regulating valve 1101 and the outlet valve 1201 are closed, the adsorption dehydration process of the liquid crude chloroethylene monomer is completed, and the adsorbent is regenerated.

[0101] (3) Adsorbent regeneration: the adsorbent regeneration process is divided into six periods:

[0102] (31) Liquid output: the liquid residual in the adsorption tower 1 is output. The liquid phase monomer outlet at the bottom of the adsorption tower 1 is connected with the crude vinyl chloride storage tank 6 through the liquid output pipeline 620, and the liquid output pipeline 620 is provided with a liquid output pump 640. The liquid output valve 630 and the liquid output pump 640 are opened, and the liquid residual in the adsorption tower 1 is output to the crude vinyl chloride storage tank 6 for temporary storage. When the second pressure sensor 1103 is less than or equal to the first set pressure value, the liquid output valve 630 and the liquid output pump 640 are closed, and the vacuum pump 5 is opened to vacuumize the adsorption tower 1. The first set pressure value is 0.1-0.15 MPa.

[0103] (32) Vacuumizing: the vacuum pump 5 and the vacuum valve 510 are opened, and the trace amount of vinyl chloride monomer residual in the adsorption tower 1 is output to the total condenser 610 under the negative pressure of the vacuum pump 5, and is condensed into liquid and temporarily stored in the crude vinyl chloride storage tank 6. When the second pressure sensor 1103 is less than or equal to the second set pressure value, the vacuum pump 5 and the vacuum valve 510 are closed, and the output of the vinyl chloride monomer in the adsorption tower 1 is completed. The second set pressure value is 0.05-0.07 MPa.

[0104] (33) Temperature rising regeneration: nitrogen is used as the regeneration gas in the embodiment. In operation, the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714, the fifth nitrogen valve 715 and the circulating pump 701 are opened. The nitrogen is output through the nitrogen main pipeline 7 under the action of the circulating pump 701, is heated in the first heat exchanger 2 to obtain high-temperature nitrogen, enters the adsorption tower 1 from the nitrogen inlet at the top of the adsorption tower 1, and moves from top to bottom to heat the high-efficiency adsorbent bed layer layer by layer. The high-efficiency adsorbent is heated to a high temperature, the water and other impurities adsorbed therein are desorbed, the adsorption sites are exposed again, and the adsorption function is restored for subsequent dehydration and adsorption. The high-temperature nitrogen is output from the nitrogen outlet at the bottom of the adsorption tower 1, is first output to the second heat exchanger 22 through the water-containing nitrogen branch pipeline 330, exchanges heat with the nitrogen passing through the second heat exchanger 22, the temperature of the nitrogen is increased, and then the nitrogen enters the first heat exchanger 2 again to exchange heat with the water vapor to increase the temperature. The high-temperature nitrogen output from the second heat exchanger 22 is sequentially output to the first condenser 3 and the second condenser 33 to be cooled and condensed, so that the water and other impurities in the water-containing nitrogen are condensed into liquid to achieve the effect of gas-liquid separation. The condensed nitrogen is pressurized by the first pressurizing pump 710 and is sent to the hot-blowing nitrogen pressurizing tank 730 for temporary storage. The liquid obtained by the first condenser 3 is used as a solvent in the lye preparation process. In the temperature rising regeneration process, the temperature of the first thermometer 1104 is 120-140°C. Preferably, the temperature of the temperature rising regeneration is 130-140°C. When the temperature detected by the second thermometer 1105 reaches 90-100°C, the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714 and the fifth nitrogen valve 715 are closed, and the temperature rising regeneration period is ended.

[0105] (34) Cooling and blowing: open the first nitrogen valve 711, the second nitrogen valve 712, the third nitrogen valve 713, the fourth nitrogen valve 714, and the sixth nitrogen valve 716. Nitrogen is output from the circulating pump 701 through the nitrogen main pipe 7, passes through the cooling and blowing nitrogen pipe 750, and enters the adsorption tower 1 from top to bottom to cool and lower the temperature of the high-temperature nitrogen. The cooled and blown nitrogen is output from the bottom of the adsorption tower 1. The nitrogen enters the first condenser 3 and the second condenser 33 through the water-containing nitrogen pipe 310 for gas-liquid separation. A small amount of water is condensed and output to the lye preparation process. The condensed nitrogen is pressurized by the second pressurizing pump 720 and sent to the cooling and blowing nitrogen pressurized tank 740 for recovery. When the temperature detected by the second thermometer 1105 is less than or equal to 50℃, stop cooling and blowing.

[0106] In this embodiment, the normal temperature refers to a temperature of 15-25℃.

[0107] When the pressure value detected by the third pressure sensor 1106 is greater than or equal to 80% of the design pressure of the hot blowing nitrogen pressurized tank 730, open the seventh nitrogen valve 717 to output the nitrogen in the hot blowing nitrogen pressurized tank 730 to the circulating nitrogen pipe 320 for use in the high-efficiency adsorbent bed warming-up regeneration period. When the pressure value detected by the fourth pressure sensor 1107 is greater than or equal to 80% of the design pressure of the cooling and blowing nitrogen pressurized tank 740, open the eighth nitrogen valve 718 to output the nitrogen in the cooling and blowing nitrogen pressurized tank 740 to the circulating nitrogen pipe 320 for use in the high-efficiency adsorbent bed warming-up regeneration period. The pressure value detected by the second pressure sensor 1103 is 0.18-0.28 MPa.

[0108] (35) Re-evacuation: open the fourth nitrogen valve 714, the nitrogen pressure relief valve 520, and the vacuum pump 5 to evacuate the nitrogen in the adsorption tower 1 to the cooling and blowing nitrogen pressurized tank 740 for temporary storage. When the reading of the second pressure sensor 1103 is less than or equal to the third set pressure value, re-evacuation is completed. The third set pressure value is 0.05-0.07 MPa.

[0109] (36) Pressure equalization: introduce gaseous chloroethylene monomer into the adsorption tower 1 to make the pressure in the adsorption tower 1 be the working pressure for chloroethylene adsorption and dehydration, and prepare for the next adsorption and dehydration work. Open the gaseous chloroethylene regulating valve 1203 and the outlet valve 1201 to introduce gaseous chloroethylene monomer into the adsorption tower 1. When the reading of the second pressure sensor 1103 is greater than or equal to the fourth set pressure value, pressure equalization is completed. The fourth set pressure value is 0.18-0.28 MPa.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that; it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A vinyl chloride monomer water removal system characterized by, The application relates to a kind of drying system of crude vinyl chloride, including: A plurality of parallelly connected adsorption towers (1), a first heat exchanger (2), a first condenser (3), a gas-liquid separator (4), a vacuum pump (5), a crude vinyl chloride storage tank (6) and a nitrogen main pipe (7); The crude vinyl chloride inlet of the adsorption tower (1) is communicated with the crude vinyl chloride storage tank (6) through a crude vinyl chloride pipeline (110), a flow regulating valve (1101) is arranged on the crude vinyl chloride pipeline (110), a first pressure sensor (1102) is arranged on the crude vinyl chloride pipeline (110) close to the inlet position of the adsorption tower (1), a second pressure sensor (1103) is arranged in the adsorption tower (1), the dehydrated vinyl chloride outlets of the adsorption tower (1) are all communicated with a dry vinyl chloride main pipe (120), and a total condenser (610) is connected to the inlet pipeline of the crude vinyl chloride storage tank (6); the liquid monomer outlet at the bottom of the adsorption tower (1) is connected with the crude vinyl chloride storage tank (6) through a liquid return pipeline (620), and a liquid return pump (640) is arranged on the liquid return pipeline (620); The nitrogen main pipe (7) is communicated with the first heat exchanger (2) through a circulating pump (701), the nitrogen outlet of the first heat exchanger (2) is communicated with a tower inlet nitrogen pipeline (210), the outlet of the tower inlet nitrogen pipeline (210) is communicated with the top gas inlet of the adsorption tower (1); the nitrogen outlet of the adsorption tower (1) is communicated with the first condenser (3) through a water-containing nitrogen pipeline (310), the liquid phase outlet of the first condenser (3) is connected with the gas-liquid separator (4), and the gas phase outlet of the first condenser (3) is connected with a circulating nitrogen pipeline (320), and the circulating nitrogen pipeline (320) is connected with the circulating pump (701); The circulating nitrogen pipeline (320) is further communicated with a first pressurizing pump (710) and a second pressurizing pump (720) through branch pipes, the first pressurizing pump (710) is connected with a hot nitrogen gas pressurizing tank (730), and the second pressurizing pump (720) is connected with a cold nitrogen gas pressurizing tank (740); the outlet of the hot nitrogen gas pressurizing tank (730) and the outlet of the cold nitrogen gas pressurizing tank (740) are both connected with the circulating nitrogen pipeline (320); a third pressure sensor (1106) is arranged in the hot nitrogen gas pressurizing tank (730), and a fourth pressure sensor (1107) is arranged in the cold nitrogen gas pressurizing tank (740); When the pressure of the hot nitrogen gas pressurizing tank (730) is greater than or equal to 80% of the design pressure, the nitrogen in the hot nitrogen gas pressurizing tank (730) is output to the circulating nitrogen pipeline (320); when the pressure of the cold nitrogen gas pressurizing tank (740) is greater than or equal to 80% of the design pressure, the nitrogen in the cold nitrogen gas pressurizing tank (740) is output to the circulating nitrogen pipeline (320); The water-containing nitrogen pipeline (310) is further connected with a vacuum pump (5), the vacuum pump (5) is connected with a vinyl chloride gas tank and the second pressurizing pump (720), and the output end of the vacuum pump (5) is further connected with the total condenser (610); The vacuum pump (5) and the second pressurizing pump (720) are connected with a pipeline which is further communicated with a nitrogen balance tank (8); the gas outlet of the nitrogen balance tank (8) is connected with the second pressurizing pump (720), and the liquid outlet of the nitrogen balance tank (8) is connected with the liquid phase outlet of the gas-liquid separator (4).

2. The vinyl chloride monomer water removal system according to claim 1, characterized by, The circulating pump (701) and the tower-entering nitrogen pipeline (210) are connected with a cold-blowing nitrogen pipeline (750).

3. The vinyl chloride monomer water removal system according to claim 1, wherein The first heat exchanger (2) and the circulating pump (701) are connected with a second heat exchanger (22). The first heat exchanger (2) and the second heat exchanger (22) both use water vapor with a temperature of 180-200 ℃ as a heat medium.

4. The vinyl chloride monomer water removal system according to claim 3, wherein The first condenser (3) is further connected with a second condenser (33). The condensing medium used by the first condenser (3) is circulating water with a temperature of 20-32 ℃, and the condensing medium used by the second condenser (33) is refrigerated water with a temperature of 3-7 ℃.

5. The vinyl chloride monomer water removal system according to claim 4, wherein The water-containing nitrogen pipeline (310) is further connected with a water-containing nitrogen branch pipeline (330). The water-containing nitrogen branch pipeline (330) is connected with the heat medium inlet of the second heat exchanger (22), and the heat medium outlet of the second heat exchanger (22) is connected with the gas phase inlet of the first condenser (3).

6. A method for removing water from vinyl chloride monomer, applied to the vinyl chloride monomer water removal system according to any one of claims 1 to 5, characterized by, The method comprises the following steps: (1) a water-containing vinyl chloride gas condensing step, in which water-containing vinyl chloride gas is sent to a total condenser for condensing to obtain liquid crude vinyl chloride monomer; (2) a vinyl chloride adsorption dehydration step, in which the liquid crude vinyl chloride monomer is moved in an adsorption tower, and water is removed under the adsorption of a high-efficiency adsorbent bed layer in the adsorption tower to obtain dry vinyl chloride; the pressure in the adsorption tower is 0.18-0.28 MPa; (3) an adsorbent regeneration step: a vacuum extraction period in the adsorption tower; hot nitrogen is introduced into the adsorption tower to regenerate the adsorbent bed layer by increasing the temperature of the water adsorbed by the adsorbent bed layer and outputting the hot nitrogen; normal-temperature nitrogen is introduced into the adsorption tower to cool the adsorbent bed layer in a cooling and cold-blowing period; the adsorption tower is vacuumed again in a vacuum extraction period; and gaseous vinyl chloride monomer is introduced into the adsorption tower to reach an equilibrium pressure of the pressure in the vinyl chloride adsorption dehydration step; the pressure in the vacuum extraction period and the vacuum extraction period is 0.05-0.07 MPa; The nitrogen output from the adsorption tower in the temperature-increasing regeneration period is sent to a hot-blowing nitrogen pressurizing tank, and the nitrogen output from the adsorption tower in the temperature-decreasing cold-blowing period is sent to a cold-blowing nitrogen pressurizing tank; The temperature in the temperature-increasing regeneration period is 130-140 ℃.

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