Method for wet condensation of polymer

Abstract

The invention discloses a polymer wet coagulation method which comprises the following steps: coagulating a polymer glue solution in at least two coagulation kettles connected in series to obtain polymer aqueous colloidal particles; wherein the steam stripping gas discharged from the first condensation kettle is cooled and then subjected to oil-water separation, and a wet solvent and layered water are obtained; the stripping gas discharged by the first condensation kettle is entrained with rubber scraps, and the method further comprises the following steps: before the stripping gas discharged by the first condensation kettle is cooled, contacting layered water with the stripping gas to take away the rubber scraps in the stripping gas, and then returning the layered water entrained with the rubber scraps to the first condensation kettle. According to the invention, on the premise of not changing the original process conditions of the steam stripping kettle, a trace amount of fine adhesive tape is returned to the first condensation kettle by using the filtering effect when layered water is in contact with the steam stripping gas, so that the amount of adhesive crumbs entrained in the steam stripping gas of the first condensation kettle is reduced; and meanwhile, layered water circularly flows and is updated constantly, so that the blocking and hanging phenomena are avoided.

Description

Technical Field

[0001] This invention relates to the field of rubber product preparation technology, and more specifically, to a method for wet polymerization of polymers. Background Technology

[0002] The solvent removal process in the solution polymerization synthesis apparatus employs a multi-stage series water separation coagulation process based on steam distillation and wet degassing. In the initial stage of coagulation, there is a constant-rate coagulation phase (the solvent vaporization stage in the solution), primarily occurring in the first coagulation vessel. Later, there is a decelerating coagulation phase (the solvent diffuses from the interior of the particles to the surface of the gel, a diffusion stage). During the constant-rate coagulation phase, approximately 95% of the total solvent is evaporated. This phase is relatively short (about a few minutes). With the vigorous evaporation of large amounts of solvent gas and water vapor, a small amount of fine gel particles near the liquid surface are inevitably entrained into the gas phase and carried to the oil-water separation tank, somewhat similar to the phenomenon commonly referred to as "fog entrainment," except that fine gel particles are also included. Since the density of both adhesive residue and solvent is less than that of water, the wet solvent and water are separated by settling in the oil-water separation tank. A small amount of fine adhesive residue goes to the downstream solvent refining unit along with the wet solvent and gradually accumulates on the heat exchange surface of the high-temperature heat exchanger. After a period of time, the heat transfer coefficient of the high-temperature heat exchanger decreases, the heat transfer temperature fails to meet the standard, the steam consumption increases, and eventually leads to an unplanned "shutdown".

[0003] In traditional processes, a filter is typically installed on the top of the condenser to reduce fine debris in the stripping gas. However, as the unit operates, the gas flow surface of the filter screen decreases, resistance increases, and gas discharge from the condenser becomes difficult. To avoid this, a backup filter must be installed in advance. These filters are usually located on the top floor of the unit's frame structure or on the roof. Cleaning a clogged filter requires using a crane to lower it to the ground, transport it outside the unit area for thorough cleaning, and then reinstalling it for future use. Throughout the production cycle, the stripping gas filter in the first condenser requires frequent cleaning, involves significant manual labor, and is costly. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of tedious removal of fine adhesive residues and high cleaning costs in the prior art, and to provide a method for wet polymer coagulation. This method can reduce the amount of adhesive residues entrained in the stripping gas of the first coagulation vessel, reduce the amount of circulating cooling water used, and also reduce the amount of steam used in the coagulation vessel.

[0005] To achieve the above objectives, the present invention provides a method for wet coagulation of polymers, the method comprising: coagulating a polymer solution in at least two coagulation vessels connected in series to obtain polymer hydrogel particles; wherein, stripping gas discharged from the first coagulation vessel is cooled and then subjected to oil-water separation to obtain a wet solvent and stratified water;

[0006] The stripping gas discharged from the first condensation vessel contains adhesive residue. The method further includes: before cooling the stripping gas discharged from the first condensation vessel, contacting the stripping gas with stratified water to remove the adhesive residue from the stripping gas, and then returning the stratified water containing adhesive residue to the first condensation vessel.

[0007] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0008] (1) Without changing the original stripping kettle process conditions, the present invention utilizes the filtration effect when the stratified water comes into contact with the stripping gas to return a small amount of fine tape to the first condensation kettle, thereby reducing the amount of adhesive debris entrained in the stripping gas of the first condensation kettle; at the same time, since the stratified water circulates and is constantly renewed, there is no clogging phenomenon.

[0009] (2) This invention achieves a double reduction in the amount of circulating cooling water and the amount of heating steam in the condenser by heat exchange during the contact between the stratified water and the stripping gas. Since the heating steam in the condenser will eventually be converted into wastewater and discharged, reducing the amount of steam will reduce the amount of wastewater discharged. Therefore, it can achieve the comprehensive effect of energy saving and emission reduction, thereby improving the overall economic and social benefits of the device. Attached Figure Description

[0010] Figure 1 This is a flow chart of the three-reactor differential pressure condensation process with stratified water tanks in Embodiment 1 of the present invention;

[0011] Figure 2 This is a flow chart of the three-reactor differential pressure condensation process with stripping gas filter in Embodiment 2 of the present invention;

[0012] Figure 3 This is a flow chart of the prior art three-reactor pressure differential coagulation process of adhesive liquid, which is Comparative Example 1 of this invention;

[0013] Figure 4a A schematic diagram of a three-reactor differential pressure condensation process with a stripper gas filter provided by one embodiment of the present invention, in which stratified water is atomized near the stripper gas outlet to form a water curtain;

[0014] Figure 4b A schematic diagram of the layered water forming a water curtain near the stripper gas outlet in a three-reactor differential pressure condensation process with a stripper gas filter provided by another embodiment of the present invention.

[0015] Explanation of reference numerals in the attached figures

[0016] R-1: First condensation vessel; R-2: Second condensation vessel; R-3: Third condensation vessel;

[0017] P-1: First coagulation reactor water-colloid pump; P-2: Second coagulation reactor water-colloid pump;

[0018] P-3: Third coagulation vessel water-colloid pump; P-4: stratification water pump; P-5: wet solvent pump;

[0019] X-1: First condensate reactor stripping gas filter; X-2: Second condensate reactor stripping gas filter;

[0020] X-3: Third condenser stripping gas filter; X-4: Injector; X-5: Water-glue mixer;

[0021] D-1: Oil-water separation tank; D-2: Separated water tank; E-1: Stripping gas condenser / cooler;

[0022] PS: Styrene-based thermoplastic elastomer solution; HW: Circulating hot water; LS: Low-pressure steam;

[0023] WS: Stripping gas or wet solvent; WR: Hydrocolloids; CS: Circulating cooling water inlet;

[0024] CR: Circulating cooling water return. Detailed Implementation

[0025] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0026] In this invention, the term "pressure" refers to gauge pressure; "glue debris" refers to fine glue particles much smaller than normal particle size, approximately less than 10 mm; "stripping gas" refers to the gas rising in the gas phase space of the condenser, part of which is solvent and the other part is water vapor; "wet solvent" refers to a solvent containing saturated water.

[0027] This invention provides a method for wet coagulation of polymers, the method comprising: coagulating a polymer solution in at least two coagulation vessels connected in series to obtain polymer hydrogel particles; wherein, stripping gas discharged from the first coagulation vessel is cooled and then subjected to oil-water separation to obtain a wet solvent and stratified water;

[0028] The stripping gas discharged from the first condensation vessel contains adhesive residue. The method further includes: before cooling the stripping gas discharged from the first condensation vessel, contacting the stripping gas with stratified water to remove the adhesive residue from the stripping gas, and then returning the stratified water containing adhesive residue to the first condensation vessel.

[0029] According to this invention, unless otherwise specified, polymeric adhesive refers to polymeric adhesive synthesized by solution method.

[0030] According to some embodiments of the present invention, the stratified water is sprayed into contact with the stripping gas in a stratified water tank, and then the stratified water and the entrained colloids are returned to the first coagulation vessel.

[0031] According to this invention, when hexane and / or cyclohexane are used as solvents for the stripping gas, the solvent is not condensed at all when passing through the stratification tank; only some water vapor is condensed into liquid, releasing latent heat of vaporization to raise the temperature of the stratified water, which then falls back to the condensation vessel along with the stratified water. Subsequently, the stripping gas is cooled by circulating cooling water in the stripping gas condenser, completely transforming from gas to liquid. Its volume shrinks rapidly, and its pressure decreases. This is the driving force that allows the stripping gas to overcome resistance and smoothly exit from the first condensation vessel. Therefore, the pressure in the stratification tank will be slightly lower than the pressure in the first condensation vessel.

[0032] According to some embodiments of the present invention, the stratified water tank is provided with a spraying device and an overflow plate. The stratified water forms a water curtain from the top of the stratified water tank through the spraying device. After contacting the stripping gas, it overflows back into the first condensation vessel along with the entrained glue debris through the overflow plate.

[0033] According to the present invention, the height of the overflow plate is not less than 2 / 3 of the liquid level.

[0034] According to the present invention, stripping gas is discharged downwards from the liquid phase of the stratified water tank through an exhaust pipe with a row of round holes or slits. After being filtered through the liquid phase layer to remove trace amounts of fine debris, it is discharged from the gas phase into the stripping gas condenser. The exhaust pipe with a row of round holes or slits should be as close as possible to the liquid surface to reduce the pressure difference between the stratified water tank and the first condensation vessel. The stratified water is pressurized by the stratified water pump and sent to the top of the stratified water tank. After forming a "water curtain" in the gas phase space through the spray device, it falls into the liquid phase and then carries the debris over a baffle and enters the liquid phase of the first condensation vessel by gravity potential energy.

[0035] According to the present invention, the stratified water tank may also be without a baffle, and the stratified water is discharged from the side of the stratified water tank to one end of the head into the first condensation vessel.

[0036] According to some embodiments of the present invention, layered water containing adhesive residue enters the first coagulation vessel from the liquid phase region of the first coagulation vessel and mixes with the polymer adhesive solution in the first coagulation vessel.

[0037] According to the present invention, since the pressure of the stratified water tank is slightly lower than that of the first condenser, in order to prevent a small amount of stripping gas from entering the stratified water tank from the stratified water inlet of the condenser, the stratified water should enter the first condenser from the liquid phase, rather than the gas phase, and form a static water column at the inlet that is slightly higher than the liquid surface of the condenser. The liquid level of this water column will rise or fall with the liquid level of the condenser. After long-term operation, a small amount of adhesive residue will be attached to the walls of the pipe where the static water column is located. It should be noted that a detachable short pipe section is provided at this point so that it can be cleaned in time during maintenance shutdowns.

[0038] The method of the present invention may also not use a stratified water tank. The stripped gas flows sequentially through a filter, a stripped gas condenser and an oil-water stratification tank. The stratified water is pressurized by a stratified water pump and added directly from the gas phase outlet of the first condensation vessel. Through a certain flow rate and design, a "water curtain" is formed in a certain area at the gas phase outlet of the first condensation vessel. When the stripped gas passes through the "water curtain", some of the entrained debris can be filtered out.

[0039] This invention, without altering the original stripping reactor process conditions, utilizes the filtration effect of the stratified water in contact with the stripping gas to return trace amounts of fine adhesive tape to the first condensation reactor, reducing the amount of adhesive debris entrained in the stripping gas of the first condensation reactor; at the same time, because the stratified water circulates and is constantly renewed, there is no clogging phenomenon, which can replace the traditional filter process.

[0040] According to some embodiments of the present invention, stratified water enters the first condensation vessel from the gas phase region, and after being atomized near the stripper gas outlet, the stratified water comes into contact with the stripper gas; the stripper gas after contact is first filtered through the stripper gas filter of the first condensation vessel, and then the filtered stripper gas is cooled.

[0041] The present invention can use various conveying methods commonly used in the art to feed the heterogeneous mixture into the first condensation vessel. Preferably, the heterogeneous mixture is fed into the first condensation vessel through a nozzle.

[0042] According to some embodiments of the present invention, the atomization is carried out by straight pipe injection, the outlet end of the straight pipe injection is a duck-shaped nozzle, the nozzle angle is 50-70°, the nozzle gap is 2-3mm, and the water flow velocity in the pipeline is greater than or equal to 2m / s.

[0043] like Figure 4a The diagram shows a three-reactor differential pressure condensation process with a stripper gas filter, where a straight-pipe jet atomizes stratified water near the stripper gas outlet to form a water curtain. Figure 4a As can be seen, the stratified water entering from the stratified water inlet is sprayed through a straight pipe into the stripper gas phase outlet pipe, forming a water curtain perpendicular to the stripper gas flow direction. When the stripper gas passes through the water curtain, the water curtain will carry away some of the colloids in the stripper gas.

[0044] According to other embodiments of the present invention, the atomization is performed by a curved pipe injection, the included angle between the inner and outer sides of the outlet guide ring of the curved pipe injection is 90-110°, the average gap of the ring is 2-3mm, and the water flow velocity in the pipeline is greater than or equal to 2.5m / s.

[0045] like Figure 4b The diagram shows a three-reactor differential pressure condensation process with a stripper gas filter, where a curved pipe jet method is used to atomize stratified water near the stripper gas outlet to form a water curtain. Figure 4b As can be seen, the stratified water entering from the stratified water inlet is sprayed through the bend pipe into the stripping gas gas phase outlet pipe to form a water curtain. When the stripping gas passes through the water curtain, the water curtain will carry away some of the debris in the stripping gas.

[0046] According to the present invention, the polymer solution is coagulated in at least two coagulation vessels connected in series, preferably in at least three coagulation vessels connected in series, and more preferably in three to five coagulation vessels connected in series.

[0047] According to some embodiments of the present invention, the coagulation is carried out using a three-reactor pressure differential coagulation method.

[0048] According to the present invention, the polymer solution synthesized by solution method is condensed using a three-reactor pressure differential condensation process.

[0049] According to some embodiments of the present invention, a polymer liquid is sequentially coagulated through a first coagulation vessel, a second coagulation vessel, and a third coagulation vessel to obtain polymer hydrogel particles; wherein, the operating pressure of the first coagulation vessel is 0.01-0.04 MPa and the temperature is 80-120°C; the operating pressure of the second coagulation vessel is 0.06-0.1 MPa and the temperature is 100-120°C; and the operating pressure of the third coagulation vessel is 0.004-0.006 MPa and the temperature is 95-105°C.

[0050] According to some embodiments of the present invention, stripping gas discharged from the second condenser and stripping gas discharged from the third condenser both enter the first condenser, and then the solvent is distilled off from the top of the first condenser.

[0051] According to a preferred embodiment of the present invention, the gas phase from the top outlets of the second and third condensing reactors enters the bottom of the first condensing reactor. The gaseous solvent is distilled off from the top of the first condensing reactor, passes through a stratification water tank or filter to remove most of the gum particles in the stripping gas, and then enters an oil-water stratification tank for stratification after being cooled by a condenser. The wet solvent and the stratified water are separated in the oil-water stratification tank, and then the wet solvent is sent to the solvent refining unit, while the stratified water is pressurized by a stratification water pump and sent back to the first condensing reactor.

[0052] According to some embodiments of the present invention, the polymer solution is mixed with circulating hot water before entering the first coagulation vessel.

[0053] According to some embodiments of the present invention, the weight ratio of rubber contained in the polymer solution to circulating hot water is 0.015-0.05:1.

[0054] According to some embodiments of the present invention, the temperature of the circulating hot water is 90-105°C.

[0055] According to some embodiments of the present invention, the method further includes: introducing steam into the bottom of the first condensing vessel and the bottom of the second condensing vessel.

[0056] According to the present invention, the steam is low-pressure steam with a temperature of 150-200°C and a pressure of 0.4-1.0 MPa.

[0057] According to the present invention, steam is introduced into the bottom of the first condensation vessel to regulate its temperature. That is, temperature compensation measures are implemented for the first condensation vessel. Specifically, the introduction of steam into the bottom of the first condensation vessel is not continuous, but only occurs when the temperature of the first condensation vessel drops due to heat loss; a small amount of steam is introduced to restore the temperature of the first condensation vessel to the aforementioned range.

[0058] According to some embodiments of the present invention, the polymer adhesive is selected from at least one of isoprene rubber adhesive, butadiene rubber adhesive, styrene-based thermoplastic elastomer adhesive, solution-polymerized styrene-butadiene rubber adhesive, and hydrogenated nitrile butadiene rubber adhesive.

[0059] According to the present invention, the solvent in the polymer solution synthesized by solution method is preferably one or more selected from cyclohexane, hexane, pentane, heptane, octane, butanone, xylene and chlorobenzene.

[0060] This invention reduces the amount of circulating cooling water used for condensing and cooling stripped gas, and also reduces the amount of steam used in the condensation reactor. Since the stratified water is typically 40–60°C, it does not contain any colloids, but it can dissolve saturated solvents at this temperature and cannot be directly discharged. It is usually used as "mechanical seal water" for water-colloid pumps, or as makeup water for the condensation system, and returned to the condensation reactor. Ultimately, it combines with excess circulating hot water to become wastewater, which is then treated to meet standards before being discharged. When the stratified water and stripped gas come into contact, heat exchange occurs. The temperature of the stratified water increases, carrying more heat, while the temperature of the stripped gas decreases slightly, causing some water vapor to recondense into liquid, reducing the amount of heat carried. This simultaneously reduces both the amount of circulating cooling water and the amount of steam used to heat the condensation reactor. Since the steam used to heat the condensation reactor is ultimately converted into wastewater for discharge, reducing the amount of steam reduces the amount of wastewater discharged. Therefore, it achieves a comprehensive effect of both energy saving and emission reduction, thereby improving overall economic and social benefits.

[0061] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0062] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0063] Example 1

[0064] The condensation process in this embodiment adopts the three-reactor pressure differential condensation method, and its process flow diagram is as follows: Figure 1 As shown, a styrene-based thermoplastic elastomer solution PS (specifically a styrene-butadiene-styrene block copolymer rubber solution, with cyclohexane as the solvent, hereinafter referred to as the adhesive solution) is fed into a water-adhesive mixer X-5 and mixed with post-treatment circulating hot water HW to obtain a heterogeneous mixture. The resulting heterogeneous mixture is fed into the first condensation vessel R-1. The stripping gas WS at the top of the vessel passes through a stratification water tank D-2 and a condenser E-1 before entering an oil-water stratification tank D-1 for stratification. The stratified wet solvent is sent to a solvent refining unit for further processing via a wet solvent pump P-5. The stratified water is pressurized by a stratification water pump P-4 and sent to a spray device in the gas phase space of the stratification water tank D-2 to form a "water curtain". After falling, it carries the filtered adhesive residue back to the first condensation vessel R-1.

[0065] Low-pressure steam LS is fed into the second condenser R-2 from the bottom. Water-gel particles WR from the bottom of the first condenser R-1 are fed into the second condenser R-2 via the first condenser water-gel particle pump P-1. Water-gel particles WR from the bottom of the second condenser R-2 are then fed into the third condenser R-3 via the second condenser water-gel particle pump P-2. Stripping gas WS from the top of the second condenser R-2 enters the bottom of the first condenser R-1 through the second condenser stripping gas filter X-2. Stripping gas WS from the top of the third condenser R-3, after passing through the third condenser stripping gas filter X-3, enters the bottom of the first condenser R-1 along with low-pressure steam ejected by steam ejector X-4. Water-gel particles WR from the bottom of the third condenser R-3 are then fed into the post-processing section for dehydration, drying, and packaging.

[0066] When the temperatures of the first condensing vessel R-1 and the second condensing vessel R-2 are lower than the preset temperatures, low-pressure steam LS is introduced from the bottom of the first condensing vessel R-1 and the bottom of the second condensing vessel R-2 respectively to adjust the temperatures of the first condensing vessel R-1 and the second condensing vessel R-2 (that is, to take temperature compensation measures for the first condensing vessel and the second condensing vessel).

[0067] The three-reactor coagulation process conditions are as follows: the top pressure of the first coagulation vessel is 0.03 MPa, the top pressure of the second coagulation vessel is 0.08 MPa, and the top pressure of the third coagulation vessel is 0.005 MPa; the bottom temperature of the first coagulation vessel is 87℃, the bottom temperature of the second coagulation vessel is 104℃, and the bottom temperature of the third coagulation vessel is 100℃; the adhesive solution temperature is 80℃; the circulating hot water temperature is 95℃; the low-pressure steam temperature is 200℃, and the pressure is 0.45 MPa. The adhesive solution concentration is 17% by weight, and the weight ratio of rubber in the adhesive solution to the circulating hot water is 0.025:1. The stratified water tank is arranged on top of the first coagulation vessel, with specifications of Φ1200mm x 2000mm, horizontal. The results are shown in Table 1.

[0068] Example 2

[0069] The condensation process in this embodiment adopts the three-reactor pressure differential condensation method, and its process flow diagram is as follows: Figure 2 As shown, compared to Example 1, the difference is that the stripping gas enters the stripping gas condenser E-1 after passing through the stripping gas filter X-1 in the first condenser, and the stratified water is pressurized by the stratified water pump P-4 and sent from the gas phase region of the first condenser R-1 into the first condenser R-1, and then... Figure 4a The straight-pipe injection mode shown atomizes the gas near the stripper gas outlet to form a water curtain, which then comes into contact with the stripper gas. Other process conditions are the same as in Example 1. The results are shown in Table 1.

[0070] Comparative Example 1

[0071] The condensation process in this embodiment adopts the three-reactor pressure differential condensation method, and its process flow diagram is as follows: Figure 3 As shown, compared with Example 2, the difference is that the stratified water is pressurized by the stratified water pump P-4 and then sent into the first condensation vessel R-1 from the liquid phase region. Other process conditions are the same as in Example 2. The results are shown in Table 1.

[0072] Table 1

[0073]

[0074] Note 1: Due to slight differences in the physical properties of the coagulated adhesive in each batch within a production cycle during actual production, the data in the table above fluctuates within a certain range. Therefore, the values ​​given in the table above are the average values ​​within a production cycle.

[0075] Note 2: During production, no temperature compensation measures are taken in the third condensation kettle, that is, steam is generally not introduced.

[0076] Note 3: During production, after the steam enters the condensation process, except for a very small portion which is used to supplement the circulating hot water consumption in the post-treatment process, the rest is eventually discharged as wastewater into the wastewater treatment system.

[0077] Note 4: "-" means none.

[0078] Note 5: Basis for calculating various costs in the implementation results: 200℃ saturated steam 350 yuan / ton; circulating cooling water with inlet / outlet water temperature of 33 / 43℃ 0.33 yuan / ton; sewage treatment cost 3 yuan / ton; stripping gas filter cleaning cost 5000 yuan / time, which is 0.5 yuan / ton of product after being included in the product cost.

[0079] As can be seen from the results in Table 1, compared with Comparative Example 1, Example 1 uses a stratified water tank, which has virtually no clogging, which is beneficial for long-term operation; the circulating water consumption is reduced by 30 t / h, and the cost is reduced by 10 yuan / ton of product; the steam consumption is reduced by 0.42 t / h, and the cost is reduced by 147 yuan / ton of product; the sewage treatment volume is reduced by 0.42 t / h, and the cost is reduced by 1.5 yuan / ton of product; the cost of cleaning the stripping gas filter is reduced by 0.5 yuan / ton of product; the electricity cost is increased by 2.5 yuan / ton of product; the total cost reduction is 159 yuan / ton of product.

[0080] From Table 1, Figure 1-4b As can be seen, Example 2 is another variation of Example 1, and its implementation effect is worse than that of Example 1, but better than that of Comparative Example 1. Comparative Example 1 did not involve contact between the stratified water and the stripping gas. Compared to Comparative Example 1, in Example 2, the amount of debris carried by the stripping gas is greatly reduced, extending the cleaning cycle of the stripping gas filter in the first condensation vessel; the circulating water consumption is reduced by 8 t / h, resulting in a cost reduction of 2.6 yuan / ton of product; the steam consumption is reduced by 0.14 t / h, resulting in a cost reduction of 49 yuan / ton of product; the wastewater treatment volume is reduced by 0.14 t / h, resulting in a cost reduction of 0.4 yuan / ton of product; and the stripping gas filter cleaning cost is reduced by 0.2 yuan / ton of product; the total cost reduction is 52.2 yuan / ton of product.

[0081] The above examples and comparative examples demonstrate that the coagulation method of the present invention has the following significant effects:

[0082] (1) Under the premise that all product indicators are qualified, the amount of circulating cooling water is reduced, the total amount of steam consumption is reduced, and the total amount of sewage treatment is reduced; the amount of stripping gas debris carried is greatly reduced, and the cleaning cycle of the stripping gas filter in the first condensation kettle is extended, which is conducive to long-term operation.

[0083] (2) Since the stratified water tank itself is small in size and does not occupy too much space, this invention can be realized simply by adding a stratified water tank without changing the layout and equipment of the existing condensation device. (Real 1240108)

[0084] I91999BHY

[0085] It is easy to implement and has low modification costs.

[0086] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for wet coagulation of polymers, characterized in that, The method includes: coagulating a polymer solution in at least two coagulation vessels connected in series to obtain polymer hydrogel particles; wherein, stripping gas discharged from the first coagulation vessel is cooled and then subjected to oil-water separation to obtain a wet solvent and stratified water; The stripping gas discharged from the first condensation vessel contains adhesive residue. The method further includes: before cooling the stripping gas discharged from the first condensation vessel, contacting the stripping gas with stratified water to remove the adhesive residue from the stripping gas, and then returning the stratified water containing adhesive residue to the first condensation vessel.

2. The method according to claim 1, wherein, The stratified water is sprayed into the stripping gas in the stratified water tank, and then the stratified water and the entrained colloid debris are returned to the first condensation vessel.

3. The method according to claim 2, wherein, The stratified water tank is equipped with a spray device and an overflow plate. The stratified water forms a water curtain from the top of the stratified water tank through the spray device. After contacting the stripping gas, it overflows back into the first condensation vessel along with the entrained glue debris through the overflow plate.

4. The method according to claim 2 or 3, wherein, Layered water containing adhesive particles enters the first coagulation vessel from the liquid phase region.

5. The method according to claim 1, wherein, The stratified water enters the first condenser from the gas phase region. After being atomized near the stripper gas outlet, the stratified water comes into contact with the stripper gas. The stripper gas after contact is first filtered through the stripper gas filter of the first condenser, and then the filtered stripper gas is cooled.

6. The method according to claim 5, wherein, The atomization is achieved by straight pipe injection, with the outlet end of the straight pipe injection being a duck-shaped nozzle. The nozzle angle is 50-70°, the nozzle gap is 2-3mm, and the water flow velocity in the pipeline is greater than or equal to 2m / s. Alternatively, the atomization is achieved by a curved pipe injection, wherein the included angle between the inner and outer sides of the outlet guide ring of the curved pipe injection is 90-110°, the average gap of the ring is 2-3mm, and the water flow velocity in the pipeline is greater than or equal to 2.5m / s.

7. The method according to any one of claims 1-6, wherein, The coagulation method employed is the three-reactor pressure differential coagulation method.

8. The method according to claim 7, wherein, The polymer solution is sequentially coagulated in a first coagulation vessel, a second coagulation vessel, and a third coagulation vessel to obtain polymer hydrogel particles. The operating pressure of the first coagulation vessel is 0.01-0.04 MPa, and the temperature is 80-120℃; the operating pressure of the second coagulation vessel is 0.06-0.1 MPa, and the temperature is 100-120℃; the operating pressure of the third coagulation vessel is 0.004-0.006 MPa, and the temperature is 95-105℃.

9. The method according to claim 8, wherein, The stripping gas discharged from the second condenser and the stripping gas discharged from the third condenser both enter the first condenser, and then the solvent is distilled off from the top of the first condenser.

10. The method according to claim 8 or 9, wherein, The polymer solution is mixed with circulating hot water before entering the first coagulation vessel; Preferably, the weight ratio of rubber to circulating hot water in the polymer solution is 0.015-0.05:1; Preferably, the temperature of the circulating hot water is 90-105℃.

11. The method according to any one of claims 8-10, wherein, The method further includes introducing steam into the bottom of the first condensation vessel and the bottom of the second condensation vessel.

12. The method according to any one of claims 1-11, wherein, The polymer solution is selected from at least one of isoprene rubber solution, butadiene rubber solution, styrene-based thermoplastic elastomer solution, solution-polymerized styrene-butadiene rubber solution, and hydrogenated nitrile butadiene rubber solution.

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