Unsteady latex volatile component removal system and method

Abstract

The invention provides a system and a method for removing unstable latex volatile components. The system comprises a heat exchanger, a devolatilization unit, a liquid storage tank, a buffer tank, a vacuum pump and an ultrasonic cleaning unit, unsteady latex is connected with an inlet of the heat exchanger, an outlet of the heat exchanger is connected with an inlet of the devolatilization unit through a first pipeline, a liquid phase outlet of the devolatilization unit is connected with a first top inlet of the liquid storage tank through a second pipeline, and a gas phase outlet of the devolatilization unit is connected with a second top inlet of the liquid storage tank through a third pipeline; a top gas phase outlet of the liquid storage tank is connected with an inlet of the buffer tank through a fourth pipeline, an outlet of the buffer tank is connected with an inlet of the vacuum pump through a fifth pipeline, an outlet of the vacuum pump is used for outputting volatile components, and a bottom latex outlet of the liquid storage tank is used for outputting devolatilized latex; the multi-probe ultrasonic cleaning unit is respectively connected with the devolatilization unit, the liquid storage tank, the buffer tank, the first pipeline and the second pipeline and is used for cleaning the equipment and the pipelines.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering, and in particular relates to a system and method for removing volatile components of non-stable latex. Background Art

[0002] Unstable latex is a liquid-solid system formed by suspension polymerization and is widely used in coatings, adhesives and latex products. The devolatilization process of unstable latex is a key link in its production process, which aims to remove unreacted monomers, volatile organic compounds and other by-products to improve product quality and environmental performance. However, the traditional devolatilization process faces many challenges in achieving continuous production.

[0003] The physical and chemical properties of non-stable latex are relatively complex, and its high solid content significantly reduces its fluidity, resulting in material accumulation and blockage during the processing process. The processing capacity of solid particles is limited, which further hinders effective mass transfer and further reduces the devolatilization efficiency, making it impossible to achieve deep devolatilization.

[0004] Therefore, it is urgent to develop a more efficient devolatilization process to improve the devolatilization efficiency of unsteady latex. Summary of the invention

[0005] The invention provides a system and method for removing non-stable latex volatiles, which are used to solve the problems in the prior art that when removing non-stable latex volatiles, material accumulation and clogging are easy to occur, and efficient continuous devolatilization is difficult.

[0006] In a first aspect, the present invention provides a system for removing volatile components of a non-stable latex, comprising: a heat exchanger, a devolatilization unit, a liquid storage tank, a buffer tank, a vacuum pump, and an ultrasonic cleaning unit;

[0007] The non-stable latex is connected to the inlet of the heat exchanger, the outlet of the heat exchanger is connected to the inlet of the devolatilization unit through a first pipeline, the liquid phase outlet of the devolatilization unit is connected to the first top inlet of the liquid storage tank through a second pipeline, the gas phase outlet of the devolatilization unit is connected to the second top inlet of the liquid storage tank through a third pipeline, the top gas phase outlet of the liquid storage tank is connected to the inlet of the buffer tank through a fourth pipeline, the outlet of the buffer tank is connected to the inlet of the vacuum pump through a fifth pipeline, the outlet of the vacuum pump is used to output volatiles, and the bottom latex outlet of the liquid storage tank is used to output the devolatilized latex;

[0008] The multi-probe ultrasonic cleaning unit is respectively connected to the devolatilization unit, the liquid storage tank, the buffer tank, the first pipeline and the second pipeline for cleaning equipment and pipelines.

[0009] Compared with the prior art, the advantages of the present invention lie in that: through the special coordination between the devolatilization unit and various components and the synergistic effect of the multi-probe ultrasonic cleaning unit, the agglomeration of solid particles can be effectively broken, the sedimentation of solid particles can be inhibited, and their interaction with the liquid can be enhanced, thereby reducing the clogging problems common in traditional equipment, improving the operating reliability and production continuity of the equipment, thereby improving the overall devolatilization efficiency and achieving deep devolatilization; and the stripping system can adjust the operating parameters according to different types of non-steady-state latex, achieving a high degree of adaptability and improving the versatility of the production line.

[0010] Further, the first pipeline is not longer than 1m; and / or,

[0011] The second pipeline is no longer than 0.5 m and extends 50% to 70% of the height of the liquid storage tank; and / or,

[0012] The third pipeline is not longer than 0.5m; and / or,

[0013] The fourth pipeline is not shorter than 1m, and the inner diameter of the pipeline within 0.4m near the gas phase outlet at the top of the liquid storage tank is not less than 200mm; and / or,

[0014] The fifth pipeline is not shorter than 0.5m.

[0015] Furthermore, the outlet of the heat exchanger is higher than the inlet of the devolatilization unit, and the number of elbows of the pipeline connecting the heat exchanger and the devolatilization unit is no more than one; and / or,

[0016] The outlet of the devolatilization unit is located vertically above the inlet of the liquid storage tank.

[0017] Furthermore, the elbow of the pipeline connecting the heat exchanger and the devolatilization unit is a curved elbow.

[0018] Furthermore, the inlet of the buffer tank includes a bottom inlet and a top inlet, and the top gas phase outlet of the liquid storage tank is connected to the bottom inlet and the top inlet of the buffer tank respectively through the fourth pipeline.

[0019] Further, a Y-type filter is provided at the inlet of the devolatilization unit; and / or,

[0020] A pipeline filter is provided at the inlet of the vacuum pump; and / or,

[0021] The fourth pipeline and / or the buffer tank are / is filled with wire mesh filler; and / or,

[0022] The inner surface of at least one of the devolatilization unit, the buffer tank, the first pipeline, the second pipeline, the third pipeline, the fourth pipeline or the fifth pipeline is provided with a chemical coating, and the chemical coating includes at least one of epoxy resin, polyurethane, perchloroethylene or ceramic.

[0023] Furthermore, the inner surface of the devolatilization unit and / or the wire mesh filler is a hydrophobic surface.

[0024] Furthermore, the thermal conductivity of the heat exchange medium of the heat exchanger is not less than 160 W / (m·K), and the temperature of the heat exchange medium is not higher than 80° C.; and / or,

[0025] The vacuum degree of the devolatilization unit is -0.070 to -0.099 MPa; and / or,

[0026] The temperature of the devolatilization unit is 30-65°C.

[0027] Furthermore, the devolatilization unit comprises at least one of a supergravity device, a tower, a rotating liquid membrane device or a fiber membrane device.

[0028] In a second aspect, the present invention provides a method for removing volatiles from an unstable latex, which is performed using the system for removing volatiles from an unstable latex according to the first aspect, and comprises the following steps:

[0029] S1, allowing the unstable latex to enter a heat exchanger for heating treatment to obtain a preheated latex;

[0030] S2, allowing the preheated latex to enter a devolatilization unit for devolatilization treatment to obtain pre-separated latex and volatile matter;

[0031] S3, the pre-separated latex falls into the liquid storage tank by itself, and the latex outlet at the bottom of the liquid storage tank outputs the devolatilized latex;

[0032] The vacuum pump sucks the volatile matter into the buffer tank through the liquid storage tank for condensation and devolatilization, and the condensed material is output as the volatile matter through the outlet of the vacuum pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of a removal system in one embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 1. Heat exchanger; 2. Devolatilization unit; 3. Liquid storage tank; 4. Buffer tank; 5. Vacuum pump; 6. Multi-probe ultrasonic cleaning unit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] First, see Figure 1 The present invention provides a system for removing volatile components of non-stable latex, comprising: a heat exchanger 1, a devolatilization unit 2, a liquid storage tank 3, a buffer tank 4, a vacuum pump 5 and a multi-probe ultrasonic cleaning unit 6;

[0038] The non-steady-state latex is connected to the inlet of the heat exchanger 1, the outlet of the heat exchanger 1 is connected to the inlet of the devolatilization unit 2 through a first pipe, the liquid phase outlet of the devolatilization unit 2 is connected to the first top inlet of the liquid storage tank 3 through a second pipe, the gas phase outlet of the devolatilization unit 2 is connected to the second top inlet of the liquid storage tank 3 through a third pipe, the top gas phase outlet of the liquid storage tank 3 is connected to the inlet of the buffer tank 4 through a fourth pipe, the outlet of the buffer tank 4 is connected to the inlet of the vacuum pump 5 through a fifth pipe, the outlet of the vacuum pump 5 is used to output volatiles, and the bottom latex outlet of the liquid storage tank 3 is used to output the devolatilized latex; the multi-probe ultrasonic cleaning unit 6 is respectively connected to the devolatilization unit 2, the liquid storage tank 3, the buffer tank 4 and the first pipe.

[0039] It can be understood that the removal system includes a vacuum pump 5 to keep the entire removal system in a vacuum state during operation.

[0040] Specifically, the unsteady latex containing volatiles enters the heat exchanger 1 through the inlet of the heat exchanger 1, and then is heated therein to obtain preheated latex; the preheated latex leaves the outlet of the heat exchanger 1, and then enters the devolatilization unit 2 through the inlet of the devolatilization unit 2, where it is devolatilized, and the pre-separated latex from which volatiles have been removed flows directly downward through the liquid phase outlet of the devolatilization unit 2 under the action of gravity, and is temporarily stored in the liquid storage tank 3, or the devolatilized latex product can be directly output through the bottom latex outlet of the liquid storage tank 3. The separated volatile gas enters the buffer tank 4 through the gas phase outlet of the devolatilization unit 2, the second top inlet of the liquid storage tank 3, the top gas phase outlet of the liquid storage tank 3 and the inlet of the buffer tank 4 in turn under the action of the vacuum pump 5, and is further condensed and separated and collected in the third pipeline, the buffer tank 4, the fourth pipeline and the fifth pipeline, and finally leaves through the outlet of the buffer tank 4 and is output through the vacuum pump 5.

[0041] Among them, the multi-probe ultrasonic cleaning unit 6 can adjust the frequency and power according to different process requirements to achieve flexible cleaning effects, and can work in coordination with other process equipment (such as vacuum pump 5, heating device, etc.) to ensure efficient and stable operation of the entire removal system.

[0042] The present invention provides a system for removing volatiles from a non-stable latex. The system can effectively break up the agglomeration of solid particles, inhibit the sedimentation of solid particles, and enhance the interaction between solid particles and liquids through the special coordination of the devolatilization unit 2 and various components and the synergistic effect of the multi-probe ultrasonic cleaning unit 6, thereby reducing the common clogging problem in traditional equipment and improving the operating reliability and production continuity of the equipment, thereby improving the overall devolatilization efficiency and achieving deep devolatilization. Finally, the volatile content of the latex product after devolatilization is significantly reduced, thereby enhancing the stability and performance of the product, which is of great significance for improving the market competitiveness of non-stable latex.

[0043] The present invention does not limit the specific type of the unsteady latex, and can be widely used in the devolatilization process of polymers produced by suspension polymerization such as polyvinylidene chloride and polymethyl methacrylate, and is particularly suitable for the implementation of the devolatilization process of polyvinyl chloride.

[0044] The stripping system of the present invention can adjust the operating parameters according to different types of non-stable latexes, thereby achieving high adaptability. Finally, the system can be widely used in the implementation of a variety of polymer stripping processes produced by suspension polymerization, thereby improving the versatility of the production line.

[0045] Furthermore, the first pipeline is not longer than 1m; the second pipeline is not longer than 0.5m and penetrates 50%-70% of the height of the liquid storage tank 3; the third pipeline is not longer than 0.5m; the fourth pipeline is not shorter than 1m, and the inner diameter of the pipeline within 0.4m near the gas phase outlet at the top of the liquid storage tank 3 is not less than 200mm; the fifth pipeline is not shorter than 0.5m.

[0046] By limiting the length of the connecting pipes between the various components, it is possible to use the liquid storage tank 3 as the dividing line, make the front-end equipment compact to reduce heat loss, and appropriately extend the pipeline at the rear end to ensure the condensation effect, thereby further improving the efficiency of removing volatiles.

[0047] Furthermore, the outlet of the heat exchanger 1 is higher than the inlet of the devolatilization unit 2 , and the number of elbows of the pipe connecting the heat exchanger 1 and the devolatilization unit 2 is no more than one; the outlet of the devolatilization unit 2 is located vertically above the inlet of the liquid storage tank 3 .

[0048] By further defining the positional relationship of each component, the heat exchanger 1 is located at a high position, which can further reduce pipe bending, weaken vacuum fluctuation caused by resistance, and further improve devolatilization efficiency.

[0049] In a specific embodiment, the elbow of the pipe connecting the heat exchanger 1 and the devolatilization unit 2 is an arc elbow, which can further reduce the vacuum fluctuation caused by resistance and further improve the devolatilization efficiency.

[0050] In a specific embodiment, the inlet of the buffer tank 4 includes a bottom inlet and a top inlet, and the top gas phase outlet of the liquid storage tank 3 is connected to the bottom inlet and the top inlet of the buffer tank 4 respectively through a fourth pipeline.

[0051] The present invention does not limit the material and structural features of the heat exchanger 1, and optionally includes a tubular heat exchanger 1 and a coil heat exchanger 1. Furthermore, the material of the heat exchanger 1 is polished.

[0052] Optionally, a Y-type filter is provided at the inlet of the devolatilization unit 2 along the material inflow direction to filter large particles in the latex to avoid clogging the devolatilization unit 2; a pipeline filter is provided at the inlet of the vacuum pump 5; this can further reduce the clogging of the pipeline by the material, improve the operating reliability and production continuity of the equipment, thereby further improving the overall devolatilization efficiency and achieving deep devolatilization.

[0053] The fourth pipe and / or the buffer tank 4 is / are plugged with wire mesh filler to further intercept water vapor and polymer particles. Optionally, the wire mesh filler is a corrugated wire mesh filler.

[0054] The inner surface of at least one of the devolatilization unit 2, the buffer tank 4, the first pipeline, the second pipeline, the third pipeline, the fourth pipeline or the fifth pipeline is provided with a chemical coating, and the chemical coating includes at least one of epoxy resin, polyurethane, perchloroethylene or ceramic.

[0055] By adding chemical coating, the sedimentation of solid particles can be further inhibited, the interaction between solid particles and liquid can be enhanced, the fluid flow performance can be further improved, and the anti-blocking performance of the equipment can be improved.

[0056] The inner surface of the devolatilization unit 2 and / or the wire mesh filler is a hydrophobic surface, which can further improve the fluid flow performance and the anti-blocking performance of the equipment.

[0057] Specifically, the thermal conductivity of the heat exchange medium of the heat exchanger 1 is not less than 160 W / (m·K); optionally, the heat exchange medium includes at least one of a copper alloy or an aluminum alloy. Using materials with high thermal conductivity helps to evenly distribute heat and avoid local overheating.

[0058] The temperature of the heat exchange medium is not higher than 80°C; the heating rate can be further controlled to achieve slow heating, further avoiding latex demulsification.

[0059] The vacuum degree of the devolatilization unit 2 is -0.070 to -0.099 MPa; the temperature of the devolatilization unit 2 is 30 to 65° C. The vacuum degree and temperature are further limited to improve the devolatilization efficiency of the unstable latex. It can be understood that different substances have different sensitivities to temperature, and the devolatilization temperature may be different.

[0060] By further limiting the execution parameters of the stripping system, the overall stripping efficiency can be further improved and deep stripping can be achieved.

[0061] Optionally, the devolatilization unit 2 includes at least one of a supergravity device, a tower, a rotating liquid film device or a fiber membrane device. Among them, the rotating liquid film device can further disperse the latex into droplets, liquid films, etc., making it easier to remove volatiles; the supergravity device and the fiber membrane device further disperse the latex into droplets by shearing, reducing the residence time of the devolatilization treatment, reducing the required processing time and energy consumption, thereby significantly reducing the production cost.

[0062] Furthermore, according to the precise temperature requirements of the removal system, multiple temperature control nodes are integrated in each pipeline, devolatilization unit 2, liquid storage tank 3, etc., and the temperature is accurately adjusted through distributed control technology.

[0063] In a second aspect, the present invention provides a method for removing volatiles from an unsteady latex, which is performed using the system for removing volatiles from an unsteady latex according to the first aspect, and comprises the following steps:

[0064] S1, allowing the unstable latex to enter the heat exchanger 1 for heating treatment to obtain preheated latex;

[0065] S2, allowing the preheated latex to enter the devolatilization unit 2 for devolatilization treatment to obtain pre-separated latex and volatile matter;

[0066] S3, the pre-separated latex falls into the liquid storage tank 3 by itself, and the latex outlet at the bottom of the liquid storage tank 3 outputs the devolatilized latex;

[0067] The vacuum pump 5 sucks the volatile matter into the buffer tank 4 through the liquid storage tank 3 for condensation and devolatilization treatment, and the condensed material is output through the outlet of the vacuum pump 5 as the volatile matter.

[0068] The present invention provides a method for removing volatiles from a non-stable latex, the beneficial effects of which are similar to those of the removal system of the first aspect, and will not be described again.

[0069] In a specific embodiment, when the unsteady latex is polyvinyl chloride, the temperature of the devolatilization treatment is 50 to 65° C., and the vacuum degree is -0.085 to -0.099 MPa.

[0070] Hereinafter, a system and method for removing volatiles from a non-stable latex provided by the present invention will be described in detail through specific embodiments.

[0071] Example 1

[0072] This embodiment adopts Figure 1 The stripping system shown in the figure is carried out, wherein the stripping unit is a supergravity device, and the vacuum degree of the stripping system is -0.072MPa; comprising the following steps:

[0073] S1, allowing the non-stable latex (polyvinyl chloride) to enter the heat exchanger for heating treatment to obtain preheated latex; wherein the latex injection volume L is 120L / h;

[0074] S2, allowing the preheated latex to enter a devolatilization unit for devolatilization treatment at 62° C. to obtain pre-separated latex and volatile matter;

[0075] S3, the pre-separated latex falls into the liquid storage tank by itself, and the latex outlet at the bottom of the liquid storage tank outputs the devolatilized latex;

[0076] The vacuum pump sucks the volatiles into the buffer tank through the liquid storage tank for condensation and devolatilization, and the condensed material is output as volatiles through the outlet of the vacuum pump.

[0077] Example 2

[0078] The present embodiment is different from the embodiment 1 in that the temperature of the devolatilization treatment is 52°C.

[0079] Example 3

[0080] Compared with Example 1, the present embodiment is different in that the devolatilization unit is a rotary liquid membrane device, and the vacuum degree of the stripping system is -0.082 MPa.

[0081] Example 4

[0082] Compared with Example 1, the present embodiment is different in that the devolatilization unit is a rotating liquid membrane device.

[0083] Example 5

[0084] Compared with Example 1, the present embodiment is different in that the devolatilization unit is a tower, and the vacuum degree of the devolatilization system is -0.08 MPa.

[0085] Test Example 1

[0086] The residual content of vinyl chloride monomer in the latex before and after removal obtained in the above example was measured by headspace gas chromatography. The results are shown in Table 1.

[0087]

[0088] It can be concluded from the results of the examples that the present invention can significantly reduce the content of vinyl chloride in polyvinyl chloride, help reduce environmental pollution, and meet the requirements of sustainable development.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein by equivalents. If these modifications and variations fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the protection scope of the present invention.

Claims

1. A system for removing volatile matter from an unsteady latex, characterized in that: include: Heat exchangers, devolatilization units, liquid storage tanks, buffer tanks, vacuum pumps and ultrasonic cleaning units; The non-stable latex is connected to the inlet of the heat exchanger, the outlet of the heat exchanger is connected to the inlet of the devolatilization unit through a first pipeline, the liquid phase outlet of the devolatilization unit is connected to the first top inlet of the liquid storage tank through a second pipeline, the gas phase outlet of the devolatilization unit is connected to the second top inlet of the liquid storage tank through a third pipeline, the top gas phase outlet of the liquid storage tank is connected to the inlet of the buffer tank through a fourth pipeline, the outlet of the buffer tank is connected to the inlet of the vacuum pump through a fifth pipeline, the outlet of the vacuum pump is used to output volatiles, and the bottom latex outlet of the liquid storage tank is used to output the devolatilized latex; The multi-probe ultrasonic cleaning unit is respectively connected to the devolatilization unit, the liquid storage tank, the buffer tank, the first pipeline and the second pipeline for cleaning equipment and pipelines.

2. The system for removing volatile matter from unstable latex according to claim 1, characterized in that: The first pipe is not longer than 1 m; and / or, The second pipeline is no longer than 0.5m and penetrates 50%-70% of the height of the liquid storage tank; and / or, The third pipeline is not longer than 0.5m; and / or, The fourth pipeline is not shorter than 1m, and the inner diameter of the pipeline within 0.4m near the gas phase outlet at the top of the liquid storage tank is not less than 200mm; and / or, The fifth pipeline is not shorter than 0.5m.

3. The system for removing volatile matter from unstable latex according to claim 2, characterized in that: The outlet of the heat exchanger is higher than the inlet of the devolatilization unit, and the number of elbows of the pipeline connecting the heat exchanger and the devolatilization unit is no more than one; and / or, The outlet of the devolatilization unit is located vertically above the inlet of the liquid storage tank.

4. The system for removing volatile matter from unstable latex according to claim 3, characterized in that: The elbow of the pipeline connecting the heat exchanger and the devolatilization unit is a curved elbow.

5. The system for removing volatile matter from unstable latex according to claim 1, characterized in that: The inlet of the buffer tank includes a bottom inlet and a top inlet, and the top gas phase outlet of the liquid storage tank is connected to the bottom inlet and the top inlet of the buffer tank respectively through the fourth pipeline.

6. The system for removing volatile matter from unstable latex according to claim 1, characterized in that: A Y-type filter is provided at the inlet of the devolatilization unit; and / or, A pipeline filter is provided at the inlet of the vacuum pump; and / or, The fourth pipeline and / or the buffer tank are / is filled with wire mesh filler; and / or, The inner surface of at least one of the devolatilization unit, the buffer tank, the first pipeline, the second pipeline, the third pipeline, the fourth pipeline or the fifth pipeline is provided with a chemical coating, and the chemical coating includes at least one of epoxy resin, polyurethane, perchloroethylene or ceramic.

7. The system for removing volatile matter from unstable latex according to claim 6, characterized in that: The inner surface of the devolatilization unit and / or the wire mesh filler is a hydrophobic surface.

8. The system for removing volatile matter from unstable latex according to any one of claims 1 to 7, characterized in that: The thermal conductivity of the heat exchange medium of the heat exchanger is not less than 160 W / (m·K), and the temperature of the heat exchange medium is not higher than 80° C.; and / or, The vacuum degree of the devolatilization unit is -0.070 to -0.099 MPa; and / or, The temperature of the devolatilization unit is 30-65°C.

9. The system for removing volatile matter from unstable latex according to claim 8, characterized in that: The devolatilization unit includes at least one of a supergravity device, a tower, a rotating liquid membrane device or a fiber membrane device.

10. A method for removing volatiles from an unstable latex, performed by using the system for removing volatiles from an unstable latex according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, allowing the non-stable latex to enter a heat exchanger for heating treatment to obtain preheated latex; S2, allowing the preheated latex to enter a devolatilization unit for devolatilization treatment to obtain pre-separated latex and volatile matter; S3, the pre-separated latex falls into the liquid storage tank by itself, and the latex outlet at the bottom of the liquid storage tank outputs the devolatilized latex; The vacuum pump sucks the volatile matter into the buffer tank through the liquid storage tank for condensation and devolatilization, and the condensed material is output as the volatile matter through the outlet of the vacuum pump.

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