Paste resin latex VCM circulation purification and removal system and process

Abstract

The present invention relates to the field of paste resin production, specifically a paste resin latex VCM circulation purification and removal system and process, including a VCM gas-liquid separation tank and a VCM gas-liquid separation tower, the two are connected in series through a VCM circulation pipeline and a discharge pipeline; the feed pipeline transports the original latex containing VCM monomers to the VCM gas-liquid separation tank for stirring, and VCM is separated from the latex during the stirring process and discharged into the VCM exhaust pipeline; the latex containing the remaining VCM gas phase enters the VCM circulation pipeline and is steam-heated to 70-80°C, and the heated latex enters the VCM gas-liquid separation tower in a vacuum environment, and VCM is recovered by spraying; the latex falling into the bottom of the tower enters the VCM gas-liquid separation tank again through the discharge pipeline, and the cycle is repeated until the latex VCM monomer content in the VCM gas-liquid separation tank reaches less than 200ppm, and the finished latex can be discharged to the next process. The present invention can remove VCM in the latex to the greatest extent, and at the same time solve the problems of agglomeration of the inner wall of the traditional stripping tower and easy clogging of the steam nozzle.

Description

Technical Field

[0001] The invention relates to the field of paste resin production, in particular to the field of removal of VCM monomers in latex during paste resin production, and specifically to a paste resin latex VCM circulation purification and removal system and process. Background Art

[0002] As the name implies, polyvinyl chloride (PVC) paste resin is mainly used in the form of paste. People often call this paste plasticized paste, which is a unique liquid form of polyvinyl chloride plastic in the unprocessed state. Paste resin is often made by emulsion and microsuspension method. At present, the application field of paste resin is constantly expanding and the market scale is constantly expanding. VCM refers to vinyl chloride, which is an important monomer used in polymer chemical industry. It can be made from ethylene or acetylene. It is a colorless, easily liquefied gas with a boiling point of -13.4℃, a critical temperature of 142℃, and a critical pressure of 5.22MPa. VCM is a toxic substance that can form an explosive mixture with air.

[0003] In the paste resin production process, the VCM recovery unit is a crucial link in the entire production process. The effect of removing VCM monomer (gas phase) in latex has an important impact on the drying process of the subsequent products and the quality of the paste resin products. In addition, the VCM that has not been removed from the latex will enter the tail gas treatment unit at the back end after the drying process. If the VCM is not completely removed, it will bring great pressure to the tail gas treatment unit. It is very likely that the tail gas treatment will not meet the emission standards, which will affect the normal production activities of the enterprise and bring great pressure to environmental protection. In addition, since the VCM monomer is highly toxic, if it is not completely treated and discharged into the atmosphere, it will also have great safety hazards.

[0004] Therefore, in the paste resin production process, the purification and removal of VCM in latex is of great significance.

[0005] In the existing paste resin production process, there are two main existing process solutions for purifying and removing VCM in latex:

[0006] Process:

[0007] This is a continuous process. In the VCM recovery unit, the latex is pumped into a horizontal VCM blowing tank. The blowing tank is tilted at a certain angle and has a stirrer at the bottom. The VCM in the latex is removed by stirring and gathered at the top of the blowing tank. After passing through the defoamer, it enters the back-end process. The main problems of this process are: the recovery (removal) of VCM is not ideal, the recovery time is long, and the effect is particularly unsatisfactory when the viscosity of the latex is high.

[0008] Stripping tower process:

[0009] This is a continuous process. The stripping tower process is to pump latex into a stripping tower. While the latex is sprinkled from top to bottom, steam is sprayed from the bottom of the tower for heating. Under vacuum conditions, VCM monomer is separated from the latex. The latex is discharged from the bottom of the stripping tower and sent to the next unit. The VCM monomer is discharged from the top of the tower and enters the back-end process. The main problems of this process are: the latex is easily sprayed onto the inner wall of the tower, attached to the inner wall, forming plasticized sheets, causing material agglomeration, and the lower steam nozzle is easily blocked; in addition, this process has difficult-to-overcome disadvantages for colloidal media: it cannot recover (eliminate) VCM well, and the recovery effect is very unsatisfactory.

[0010] In addition, the existing pipeline distributor or nozzle is used to spray the material downward, but this method is not suitable for resins with high viscosity (viscosity of 10~20cp) and possible particles. It is easy to clog the nozzle and pipeline openings, and it cannot meet the needs of the production process in terms of spraying area, spraying liquid surface shape, spraying intensity, etc., which makes it easy for latex to be sprayed on the inner wall of the stripping tower, affecting the removal of VCM monomer and the recovery of latex. In addition, the existing process scheme cannot adjust and control multiple parameters of material spraying, which greatly affects the conversion rate of materials and product quality. Summary of the invention

[0011] The purpose of the present invention is to provide a paste resin latex VCM circulation purification removal system and process, which can remove VCM in the latex to the maximum extent and solve the problems of agglomeration on the inner wall of the stripping tower, difficulty in adjusting the spraying parameters and easy clogging of the steam nozzle.

[0012] The invention discloses a VCM circulation purification and removal system for paste resin latex, comprising a VCM gas-liquid separation tank and a VCM gas-liquid separation tower, which are connected in series through a VCM circulation pipeline and a discharge pipeline.

[0013] The feed pipeline transports the original latex containing VCM monomer to the inclined VCM gas-liquid separation tank for stirring. During the stirring process, VCM is separated from the latex and discharged into the VCM exhaust pipeline; the latex containing the remaining VCM gas phase enters the VCM circulation pipeline and is heated to 70-80°C by steam. The heated latex then enters the VCM gas-liquid separation tower in a vacuum environment and VCM is recovered by spraying; the latex that falls to the bottom of the tower enters the VCM gas-liquid separation tank again through the discharge pipeline, and the cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank reaches below 200ppm, and the finished latex can be discharged to the next process.

[0014] Furthermore, a stirring device is provided in the VCM gas-liquid separation tank near the original latex feed port, the electrical control part of the stirring device is arranged at the top of the outer side of the tank body, a stirring rod is connected below the electrical control part, and the stirring rod extends downward to the bottom of the VCM gas-liquid separation tank; at least two layers of stirring blades are provided axially on the stirring rod; the foam layer of the VCM gas-liquid separation tank is provided with at least one layer of stirring blades, and the edge of the stirring blade in the foam layer is provided with a needle-like structure.

[0015] Furthermore, a foam baffle is provided in the VCM gas-liquid separation tank, and the foam baffle extends downward from the top of the VCM gas-liquid separation tank to the center of the tank cross section; and the foam baffle is densely covered with defoaming holes on the plate body.

[0016] Furthermore, a plurality of spikes are arranged around the inner wall of the foam removal hole, and the spikes extend from the inner wall of the foam removal hole toward the center.

[0017] Furthermore, the VCM circulation pipeline is provided with a latex circulation pump, a Venturi mixer and a hot steam delivery pipeline. The latex circulation pump is used to deliver the latex to the VCM gas-liquid separation tower; the hot steam delivery pipeline is used to deliver the hot steam to the Venturi mixer, and the latex enters the VCM gas-liquid separation tower after being heated by the hot steam in the Venturi mixer; a temperature regulating valve and a pressure regulating valve are installed on the hot steam delivery pipeline to respectively adjust the temperature and pressure of the hot steam.

[0018] Furthermore, the latex is sprayed into the VCM gas-liquid separation tower through a fluid shaping valve; the fluid shaping valve includes an electric actuator and a main valve body; the main valve body includes a valve core and an outer shell body mounted on the outside thereof; the output end of the electric actuator is connected to the top of the valve core and can drive the valve core to rise and fall, a shaping plate is provided at the bottom of the valve core, and a material inlet connected to a Venturi mixer is provided on one side above the outer shell body; the space between the outer shell body and the valve core provides a tangible channel for the flow of latex, and the latex entering the channel is sprayed out through the gap between the bottom of the outer shell body and the shaping plate.

[0019] Furthermore, a cooling pipe is arranged on the outer wall of the VCM gas-liquid separation tower from top to bottom.

[0020] The present invention also discloses a VCM purification and removal process for paste resin latex, comprising the following steps:

[0021] Step 1: The latex enters the VCM gas-liquid separation tank in a vacuum environment through a feed pipeline, and the stirring device stirs the latex in the tank. During the stirring process, the VCM gas in the liquid phase rises, and the foam on the upper layer of the liquid phase is broken by the stirring blades on the upper layer; the foam that is not broken gathers at the foam baffle and breaks when passing through the defoaming hole;

[0022] Step 2: VCM gas released from the latex gradually gathers and enters the exhaust line;

[0023] Step 3: The latex containing the remaining VCM enters the Venturi mixer under the action of the latex circulation pump; hot steam is introduced into the Venturi mixer to mix with the latex, and the heated latex is about 70-80 degrees and enters the fluid shaping valve through the material inlet;

[0024] Step 4: The latex is sprayed out through the annular gap between the shaping plate and the outer shell, and the height of the latex spraying gap is L; the vacuum degree in the VCM gas-liquid separation tower is 10~20KPa. Under this condition, the VCM monomer is further separated from the latex and discharged from the top of the VCM gas-liquid separation tower to enter the back-end process link;

[0025] Step 5. Due to the existence of the cooling pipe, a small amount of latex sprayed onto the wall of the VCM gas-liquid separation tower is not easy to form plasticized sheets; most of the latex is discharged from the bottom of the VCM gas-liquid separation tower to the discharge pipeline and enters the VCM gas-liquid separation tank, and this cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank reaches below 200ppm, and then it can be discharged through the finished latex discharge port to the next process.

[0026] Furthermore, when the latex temperature of the VCM gas-liquid separation tank is 70-80° C., the vacuum degree of the VCM gas-liquid separation tank is selected to be 10-20 KPa.

[0027] Furthermore, the volume range of the VCM gas-liquid separation tank is 50-80m 3 The diameter of the VCM gas-liquid separation tower ranges from 2100 to 2500 mm, and the flow rate of the latex circulation pump is 0 to 25 m 3 / h;

[0028] When the latex circulation pump flow rate Q is set to 10 m 3 / h, the latex spray gap height L is selected to be 12mm.

[0029] The beneficial effects of the present invention are:

[0030] The present invention connects the VCM gas-liquid separation tank and the VCM gas-liquid separation tower in series as a whole through a VCM circulation pipeline, and realizes the gradual separation of VCM gas through the reciprocating operation in the above two devices; specifically:

[0031] First, the VCM monomer is initially separated through the VCM gas-liquid separation tank, and a stirring device and a foam baffle are set in the VCM gas-liquid separation tank to enhance the removal efficiency of the VCM monomer in the latex, reduce the latex foam entrained into the gas phase, enter the rear system, and cause the dryer to be blocked; then the latex containing the remaining VCM monomer is heated outside the tower to solve the problem of easy blockage of the hot steam pipe in the traditional process; at least two layers of stirring blades are arranged axially on the stirring rod; the stirring blades in the latex liquid phase play a stirring role to make VCM escape better. The stirring blades in the foam layer play a defoaming role; the setting of the foam baffle further enhances the defoaming effect; 3. The heated latex enters the VCM gas-liquid separation tower for spraying, and the VCM monomer in the latex is removed under a vacuum environment; for fluids with a viscosity of 10~20cp, a fluid plastic valve with fine adjustment of flux, spray intensity, spray area, and collision shape is provided, which solves the problem that the traditional material spray parameters are fixed and cannot be adjusted, and improves the material conversion rate and product quality;

[0032] 4. The space between the outer shell and the valve core of the fluid plastic valve provides a large-flux tangible channel for the flow of latex. The latex is sprayed out through the gap between the bottom of the outer shell and the plastic plate, which can be adjusted at any time, solving the problem of easy clogging of the spray channel by materials in this field;

[0033] 5. The outer wall of the VCM gas-liquid separation tower is surrounded by cooling pipes, which reduces the possibility of plasticization of latex on the inner wall of the tower and is conducive to the recovery of latex. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a schematic diagram of the paste resin latex VCM circulation purification and removal system of the present invention;

[0035] Figure 2 is a schematic diagram of a fluid shaping valve of the present invention;

[0036] Figure 3 is the relationship between the vacuum degree inside the VCM gas-liquid separation tank and the VCM content in the latex in the present invention;

[0037] Figure 4 It is a schematic diagram of latex entering the VCM gas-liquid separation tower through a fluid shaping valve in the present invention;

[0038] Figure 5 It is a relationship diagram between the latex spraying gap height L and the latex spraying radius R in the present invention.

[0039] Figure: 1, VCM gas-liquid separation tank; 11, feed pipeline; 12, stirring device; 13, foam baffle; 14, gas outlet; 15, circulating latex outlet; 16, VCM exhaust pipeline;

[0040] 2. VCM circulation pipeline; 21. Latex circulation pump; 22. Venturi mixer; 23. Hot steam delivery pipeline; 3. VCM gas-liquid separation tower; 31. Cooling pipeline; 4. Fluid shaping valve; 41. Electric actuator; 42. Valve core; 43. Outer shell; 44. Shaping plate; 45. Material inlet; 5. Discharge pipeline. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0042] like Figures 1 to 5 As shown, the present invention provides a paste resin latex VCM circulation purification and removal system, including a VCM gas-liquid separation tank 1 and a VCM gas-liquid separation tower 3, which are connected in series through a VCM circulation pipeline and a discharge pipeline.

[0043] The VCM gas-liquid separation tank 1 is improved from the blow-off tank in the prior art, and its specific structure is a horizontal closed cylindrical tank body and is inclined at a certain angle; the lower side of the VCM gas-liquid separation tank 1 is provided with an original latex feed port, a circulating latex feed port and a finished latex discharge port; the higher side is provided with a gas discharge port 14 and a circulating latex discharge port 15.

[0044] The VCM circulation pipeline includes a VCM circulation pipeline 2 and a discharge pipeline 5; the VCM circulation pipeline 2 is connected between the circulating latex discharge port 15 of the VCM gas-liquid separation tank 1 and the feed end of the VCM gas-liquid separation tower 3; the discharge pipeline 5 is connected between the discharge end of the VCM gas-liquid separation tower 3 and the circulating latex feed port of the VCM gas-liquid separation tank 1.

[0045] The feed line 11 conveys the original latex containing VCM monomer to the VCM gas-liquid separation tank 1 for stirring, and the purpose of preliminary separation of VCM from the latex is achieved during the stirring process; the VCM gas is discharged into the VCM exhaust pipeline 16 through the gas outlet 14; the latex containing the remaining VCM gas phase enters the VCM gas-liquid separation tower 3 through the circulating latex outlet 15 and the VCM circulating pipeline 2 for further recovery; and then enters the VCM gas-liquid separation tank 1 again through the discharge pipeline 5 to recover the VCM monomer, and this cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank 1 reaches below 200 ppm, and then it can be discharged to the next process through the finished latex outlet.

[0046] A stirring device 12 is provided in the VCM gas-liquid separation tank 1 near the original latex feed port. The stirring device 12 is vertically arranged, and the electrical control part of the stirring device is arranged on the top of the outer side of the tank body. A stirring rod is connected below the electrical control part, and the stirring rod extends downward to the bottom of the VCM gas-liquid separation tank 1. Since a large amount of foam will be generated on the surface of the latex liquid phase during the stirring process, it is necessary to remove the foam to facilitate the discharge of VCM gas and reduce the entrainment of latex foam into the gas phase and enter the rear system to cause the dryer to be blocked. Therefore, at least two layers of stirring blades are provided on the stirring rod along the axial direction. The stirring blades in the latex liquid phase play a stirring role to make the VCM escape better. The foam layer is provided with at least one layer of stirring blades, and the edge of the stirring blades in the foam layer is provided with a needle-like structure to achieve a defoaming effect; in order to further enhance the defoaming effect, a semicircular foam baffle 13 is arranged in the VCM gas-liquid separation tank 1, and the foam baffle 13 extends downward from the top of the VCM gas-liquid separation tank 1 to the center of the tank cross section to fully intercept the foam, and the plate body is densely covered with defoaming holes, and the inner wall of the defoaming hole is surrounded by a plurality of spikes, and the spikes extend from the inner wall of the defoaming hole to the center so that the foam is punctured when passing through the hole; in order to achieve a better defoaming effect, multiple layers of foam baffles 13 can be evenly arranged in the VCM gas-liquid separation tank 1.

[0047] Preferably, the gas outlet 14 is arranged at the top of the VCM gas-liquid separation tank 1, and the circulating latex outlet 15 is arranged at the bottom of the VCM gas-liquid separation tank 1; the inclination angle of the VCM gas-liquid separation tank 1 is 3-5°, and the setting of this angle facilitates the upward transportation of VCM gas without hindering the circulation of latex.

[0048] Preferably, the temperature of the latex returned to the VCM gas-liquid separation tank 1 is 70-80°C. Through relevant experiments, the relationship between the vacuum pressure (20KPaA~60KPaA) inside the VCM gas-liquid separation tank 1 and the VCM content in the latex can be obtained; the experimental data are as follows Figure 3 As shown: when the latex temperature of VCM gas-liquid separation tank 1 is 75℃, at the beginning, as the internal pressure of VCM gas-liquid separation tank 1 decreases (vacuum degree increases), not only the mass transfer driving force increases, but also the gas-liquid mass transfer interface area increases, which is conducive to the removal of VCM from latex, and the VCM content in latex is significantly reduced. When the vacuum degree is reduced to 25KPa, the VCM content in latex is 225ppm; when the vacuum degree is reduced to 20KPa, the VCM content in latex is 191ppm; the vacuum degree continues to decrease to 10KPa, and the VCM content in latex changes very little. Therefore, in order to ensure that the VCM content in the latex output is less than 200ppm, the optimal operating vacuum degree of the VCM gas-liquid separation tank is 10-20KPa.

[0049] The VCM circulation pipeline 2 is provided with a latex circulation pump 21, a venturi mixer 22 and a hot steam delivery pipeline 23, wherein the latex circulation pump 21 is used to deliver the latex to the VCM gas-liquid separation tower 3; the hot steam delivery pipeline 23 is used to deliver hot steam to the venturi mixer, the hot steam is mixed with the latex and the hot steam is heated and then delivered to the VCM gas-liquid separation tower; a temperature regulating valve and a pressure regulating valve are installed on the hot steam delivery pipeline 23 to adjust the temperature and pressure of the hot steam respectively; during production, heating is required to remove VCM from the latex; compared with the prior art in which hot steam is input upward from the bottom of the stripping tower, the present application heats the latex before it enters the VCM gas-liquid separation tower 3, thereby solving the problem that the sprayed latex is prone to clogging the steam nozzle.

[0050] The VCM gas-liquid separation tower 3 is improved on the basis of the existing stripping tower. In the prior art, the sprayed latex falls on the inner wall of the stripping tower, which is easy to form plasticized sheets; in order to solve this problem, the present invention has a cooling pipe 31 arranged on the outer wall of the VCM gas-liquid separation tower 3 from top to bottom, and the tower wall is cooled by inputting circulating cooling water to prevent the latex from plasticizing into sheets.

[0051] Preferably, the latex is sprayed into the VCM gas-liquid separation tower 3 through a fluid shaping valve 4; the fluid shaping valve 4 includes an electric actuator 41 and a main valve body; the main valve body includes a valve core 42 and an outer shell 43, the top of the valve core 42 is connected to the output end of the electric actuator 41, and the bottom is provided with a shaping plate 44 as a core component for spray parameter control; the cross-section of the shaping plate 44 is adapted to the shape and size of the inner cavity of the outer shell, the bottom of the bottom shaping plate 44 is flush, and the top can be set to a flat top or an arc top; the outer shell 43 is sleeved on the outside of the valve core 42, and the outer shell 43 is connected to the top of the VCM gas-liquid separation tower 3 It is connected by flanges; a material inlet 45 is provided on one side above the outer shell 43, and the material inlet 45 is connected to the discharge end of the venturi mixer 22 through a corresponding pipeline; since the space between the outer shell 43 and the valve core 42 provides a large-throughput latex channel for the flow of latex, the latex is ejected through the adjustable annular gap between the bottom of the outer shell 43 and the shaping plate 44. The design of this large-throughput latex channel not only provides sufficient circulation space for the latex, but also allows the latex to be subjected to uniform pressure and velocity distribution during the flow process, solving the problem of easy clogging of the spray channel by materials in this field. The material inlet 45 is connected to the main valve body at an angle downward to reduce the feed resistance, ensuring that the latex can smoothly enter the fluid shaping valve 4.

[0052] In actual production, the length of the valve core 42 and the outer shell 43 can be changed according to the working conditions to change the spray height; in addition, the electric actuator 41 can use compressed air or electricity as a power source to control the rise and fall of the valve core 42, thereby achieving the adjustment of the spray intensity and area. Figure 4As shown, when the amount of latex introduced remains unchanged, the closer the shaping plate 44 is to the bottom of the shell, the smaller the latex spray gap height L is, the higher the spray intensity is, and the larger the spray radius R is. Conversely, the farther the shaping plate 44 is from the bottom of the shell, the larger the latex spray gap height L is, the lower the spray intensity is, and the smaller the spray radius R is.

[0053] Preferably, the volume range of the VCM gas-liquid separation tank applicable to the present invention is 50-80m 3 The diameter of the VCM gas-liquid separation tower ranges from 2100 to 2500 mm, and the flow rate of the latex circulation pump is 0 to 25 m 3 / h.

[0054] The present invention explores the relationship between the latex spraying gap height L and the latex spraying radius R when the flow rate Q of the latex circulation pump 21 is constant through relevant experiments:

[0055] The flow rate Q of the latex circulation pump is set to 10 m 3 / h, the latex spray gap height L is adjusted between 11mm and 17mm. During the adjustment process, the change of the latex spray radius R at the outlet of the fluid shaping valve is observed. The larger the R value, the better the spray effect, which is more conducive to the escape of VCM in the latex. However, the R value should also be controlled to be less than the radius D / 2 of the VCM gas-liquid separation tower to avoid latex sticking to the wall. The radius D of the VCM gas-liquid separation tower is preferably 1.15m. The results are as follows Figure 5 It can be seen that when the latex spray gap height L is selected to be 12mm, the spray radius R=1.06m, and the operating parameters are optimal.

[0056] In actual production, the spray shape can also be changed by changing the shapes of the outer shell 43 and the matching valve core 44, for example, changing them to a circle or a square; multiple spray holes can also be set on the shaping plate 44 at a position opposite to the latex channel; or only the top shape of the shaping plate 44 can be changed, for example, the top curve of the shaping plate 44 is set to an umbrella shape with a certain regularity, so as to effectively control the shape of the spray liquid, make the spray area of ​​the latex as large as possible, and at the same time all of it will be sprayed to the bottom of the tower and enter the discharge pipeline 5.

[0057] Preferably, a remote pressure gauge, flow meter and regulating valve are provided on the pipeline between the material inlet 45 and the Venturi mixer 22 to control the flow and pressure of the material entering the fluid shaping valve 4 to achieve fine adjustment of various parameters of the spraying material at the outlet of the fluid shaping valve 4, thereby making the present invention applicable to various process production links under similar working conditions.

[0058] Example 3

[0059] The present invention discloses a process for purifying and removing VCM of a paste resin latex, comprising the following steps:

[0060] Step 1: latex enters the VCM gas-liquid separation tank 1 through the feed pipeline 11, and the stirring device 12 stirs the latex in the tank. During the stirring process, the VCM gas in the liquid phase rises, and the foam on the upper layer of the liquid phase is broken by the stirring blades on the upper layer. The foam that is not broken gathers at the foam baffle 13 and breaks when passing through the defoaming hole;

[0061] Step 2: The VCM gas released from the latex gradually gathers toward the discharge end and enters the exhaust pipeline;

[0062] Step 3: The latex containing VCM enters the Venturi mixer 22 under the action of the latex circulation pump; hot steam with a pressure of 1.0 MPa and a temperature of 180 degrees Celsius is introduced into the Venturi mixer to mix with the latex, and the heated latex is about 70-80 degrees and enters the fluid shaping valve 4 through the material inlet 45;

[0063] Step 4: The electric actuator 41 drives the valve core 42 to rise and fall, and adjusts the shaping plate 44 to a preset height, and the latex is ejected through the annular gap between the shaping plate 44 and the outer shell 43; the vacuum degree in the VCM gas-liquid separation tower is 10-20KPa, under which the VCM monomer is further separated from the latex and discharged from the top of the tower to enter the back-end process link;

[0064] Step 5. Due to the presence of the cooling pipe 31, a small amount of latex sprayed onto the wall of the VCM gas-liquid separation tower 3 is not easy to form a plasticized sheet; most of the latex is discharged from the bottom of the VCM gas-liquid separation tower to the discharge pipeline 5 and enters the VCM gas-liquid separation tank 1, and this cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank 1 reaches below 200ppm, and then it can be discharged through the finished latex discharge port to the next process.

[0065] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed by the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A paste resin latex VCM circulation purification and removal system, characterized in that: It includes a VCM gas-liquid separation tank and a VCM gas-liquid separation tower, which are connected in series through a VCM circulation pipeline and a discharge pipeline; The original latex containing VCM monomer is transported to the inclined VCM gas-liquid separation tank through the feed pipeline for stirring. During the stirring process, VCM is separated from the latex and discharged into the VCM exhaust pipeline; the latex containing the remaining VCM gas phase enters the VCM circulation pipeline and is heated to 70-80°C by steam. The heated latex then enters the VCM gas-liquid separation tower in a vacuum environment and VCM is recovered by spraying; the latex falling to the bottom of the tower enters the VCM gas-liquid separation tank again through the discharge pipeline, and the cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank reaches less than 200ppm, and the finished latex can be discharged to the next process; the latex is sprayed into the VCM gas-liquid separation tower through a fluid shaping valve; The VCM circulation pipeline is provided with a latex circulation pump, a venturi mixer and a hot steam delivery pipeline. The latex circulation pump is used to deliver the latex to the VCM gas-liquid separation tower; the hot steam delivery pipeline is used to deliver the hot steam to the venturi mixer, and the latex enters the VCM gas-liquid separation tower after being heated by the hot steam in the venturi mixer; a temperature regulating valve and a pressure regulating valve are installed on the hot steam delivery pipeline to adjust the temperature and pressure of the hot steam respectively; The fluid shaping valve includes an electric actuator and a main valve body; the main valve body includes a valve core and an outer shell body mounted on the outside thereof; the output end of the electric actuator is connected to the top of the valve core and can drive the valve core to rise and fall, and a shaping plate is provided at the bottom of the valve core, and the cross-section of the shaping plate is adapted to the shape and size of the inner cavity of the outer shell body; a material inlet connected to a Venturi mixer is provided on one side above the outer shell body; the space between the outer shell body and the valve core provides a tangible channel for the flow of latex, and the latex entering the channel is ejected through the gap between the bottom of the outer shell body and the shaping plate.

2. The paste resin latex VCM circulation purification and removal system as claimed in claim 1, characterized in that: A stirring device is provided in the VCM gas-liquid separation tank near the original latex feed port, the electrical control part of the stirring device is arranged on the top of the outer side of the tank body, a stirring rod is connected below the electrical control part, and the stirring rod extends downward to the bottom of the VCM gas-liquid separation tank; at least two layers of stirring blades are provided on the stirring rod along the axial direction; the foam layer of the VCM gas-liquid separation tank is provided with at least one layer of stirring blades, and the edges of the stirring blades in the foam layer are provided with a needle-like structure.

3. The paste resin latex VCM circulation purification and removal system as claimed in claim 1, characterized in that: A foam baffle is arranged in the VCM gas-liquid separation tank, and the foam baffle extends downward from the top of the VCM gas-liquid separation tank to the center of the tank cross section; and the foam baffle is densely covered with defoaming holes on the plate body.

4. The paste resin latex VCM circulation purification and removal system as claimed in claim 3, characterized in that: A plurality of spikes are arranged around the inner wall of the foam removal hole, and the spikes extend from the inner wall of the foam removal hole toward the center.

5. The paste resin latex VCM circulation purification and removal system as claimed in claim 1, characterized in that: A cooling pipe is arranged on the outer wall of the VCM gas-liquid separation tower from top to bottom.

6. The process of the paste resin latex VCM circulation purification and removal system as claimed in claim 3, characterized in that: The steps include: Step 1: The latex enters the VCM gas-liquid separation tank in a vacuum environment through a feed pipeline, and the stirring device stirs the latex in the tank. During the stirring process, the VCM gas in the liquid phase rises, and the foam on the upper layer of the liquid phase is broken by the stirring blades on the upper layer; the foam that is not broken gathers at the foam baffle and breaks when passing through the defoaming hole; Step 2: VCM gas released from the latex gradually gathers and enters the exhaust line; Step 3: The latex containing the remaining VCM enters the Venturi mixer under the action of the latex circulation pump; hot steam is introduced into the Venturi mixer to mix with the latex, and the heated latex is 70-80 degrees and enters the fluid shaping valve through the material inlet; Step 4: The latex is sprayed out through the annular gap between the shaping plate and the outer shell, and the height of the latex spraying gap is L; the vacuum degree in the VCM gas-liquid separation tower is 10~20KPa. Under this condition, the VCM monomer is further separated from the latex and discharged from the top of the VCM gas-liquid separation tower to enter the back-end process link; Step 5. Due to the existence of the cooling pipe, a small amount of latex sprayed onto the wall of the VCM gas-liquid separation tower is not easy to form plasticized sheets; most of the latex is discharged from the bottom of the VCM gas-liquid separation tower to the discharge pipeline and enters the VCM gas-liquid separation tank, and this cycle is repeated until the VCM monomer content of the latex in the VCM gas-liquid separation tank reaches below 200ppm, and then it can be discharged through the finished latex discharge port to the next process.

7. The process of the paste resin latex VCM circulation purification and removal system as claimed in claim 6, characterized in that: When the latex temperature of the VCM gas-liquid separation tank is 70-80° C., the vacuum degree of the VCM gas-liquid separation tank is selected to be 10-20 KPa.

8. The process of the paste resin latex VCM circulation purification and removal system as claimed in claim 6, characterized in that: The volume range of the VCM gas-liquid separation tank is 50~80m 3 The diameter of the VCM gas-liquid separation tower ranges from 2100 to 2500 mm, and the flow rate of the latex circulation pump is 0 to 25 m 3 / h; When the latex circulation pump flow rate Q is set to 10 m 3 / h, the latex spray gap height L is selected to be 12mm.

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