CN112111026B

CN112111026B - Method for coagulating isoprene rubber solution

Info

Publication number: CN112111026B
Application number: CN201910539162.5A
Authority: CN
Inventors: 徐林; 邰峰; 李巍; 张国娟
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2019-06-20
Filing date: 2019-06-20
Publication date: 2022-08-19
Anticipated expiration: 2039-06-20
Also published as: CN112111026A

Abstract

The invention relates to the field of rubber product preparation, and discloses a method for coagulating isoprene rubber solution, which comprises the following steps: feeding the heterogeneous mixture into a first condensation kettle, a second condensation kettle and a third condensation kettle in sequence to remove the solvent; the heterogeneous mixture is obtained by mixing the post-treatment circulating hot water A and an isoprene rubber solution. The method can fully recycle the steam condensate with higher enthalpy and reduce the discharged sewage quantity of the device.

Description

Method for coagulating isoprene rubber solution

Technical Field

The invention relates to the field of rubber product preparation, in particular to a method for coagulating isoprene rubber solution.

Background

The solvent removing process of the solution polymerization synthesis device adopts a multi-kettle series connection elutriation method coagulation process based on the steam distillation and wet degassing. In the traditional process design, the heat supply mode of the process is that steam is directly communicated for supplying heat, the process is simple in route and high in heat utilization efficiency, but the process has the problem that in order to balance the material inlet and outlet, oily sewage with the same amount as the steam inlet and outlet must be discharged out of a system, and the process has increasingly embodied limitations at present when the pollution discharge amount and the standard of chemical production devices are increasingly strict.

Disclosure of Invention

The invention aims to improve the sewage discharge of the device, and provides heat required by partial steam stripping by heating circulating hot water to an overheated state and introducing the superheated circulating hot water into a steam stripping kettle in a way of changing the heat supply mode in the condensation process on the premise of not changing the process conditions of the original steam stripping kettle. The method can reduce the amount of sewage discharged by the device, and the steam condensate with higher enthalpy can be fully reused, thereby improving the heat utilization efficiency of the device.

In order to achieve the above object, the present invention provides a method for coagulating an isoprene rubber solution, the method comprising: feeding the heterogeneous mixture into a first condensation kettle, a second condensation kettle and a third condensation kettle in sequence to remove the solvent; the heterogeneous mixture is obtained by mixing the post-treatment circulating hot water A and an isoprene rubber solution.

Preferably, a three-pot differential pressure coagulation process is employed.

Preferably, before the post-treatment circulating hot water A is mixed with the isoprene rubber solution, the first steam condensate and the isoprene rubber solution are subjected to second heat exchange, so that the first steam condensate is further cooled to obtain second steam condensate.

Preferably, the steam temperature is 125-200 ℃.

Preferably, the superheated water temperature is 125-145 ℃.

Preferably, the weight ratio of the isoprene rubber contained in the isoprene rubber solution to the total amount of the post-treatment circulating hot water A and B is 0.025-0.075: 1.

preferably, the temperature of the first steam condensate water is 140-200 ℃, the pressure is 0.4-0.8MPa, the temperature of the second steam condensate water is 85-125 ℃, and the pressure is 0.4-0.8 MPa.

Preferably, the weight ratio of the post-treatment circulating hot water B to the post-treatment circulating hot water a is 0.15-0.4: 1.

preferably, the gas phase at the top outlets of the second condensation kettle and the third condensation kettle enters the bottom of the first condensation kettle, and the solvent gas phase is evaporated from the top of the first condensation kettle, passes through a stripping gas filter and a condensation cooler and then enters the oil-water layering tank for layering.

Preferably, the operating pressure of the first coagulation-up kettle is 0.01-0.03MPa, and the temperature is 80-90 ℃.

Preferably, the operating pressure of the second condensation kettle is 0.06-0.1MPa, and the temperature is 100-120 ℃.

Preferably, the third coagulation-up kettle is operated at a pressure of 0.004-0.006MPa and a temperature of 95-115 ℃.

Preferably, the isoprene rubber solution is a rare earth isoprene rubber solution.

According to the traditional multi-kettle condensation process, steam directly enters a condensation kettle to provide heat, then is changed into steam condensate water which enters a post-treatment process along with colloidal water particles, hot water is recycled and then returns to the condensation process for recycling (namely post-treatment circulating hot water), and in order to balance the circulating hot water quantity, the circulating hot water changed from the steam is changed into sewage to be discharged after deducting the hot water loss quantity of the post-treatment process; by the method provided by the invention, steam does not directly enter the condensation kettle any more, but exchanges heat with part of circulating hot water to change the circulating hot water into superheated water to enter the condensation kettle, so that the condensation effect of the condensation kettle is ensured, the external discharge of sewage is reduced, the environmental protection requirement is met, and the subsequent sewage treatment cost is reduced.

Drawings

FIG. 1 is a flow chart of a three-pot differential pressure coagulation process for a dope in example 1.

FIG. 2 is a flow chart of a three-pot differential pressure coagulation process of the prior art cement in comparative example 1.

Description of the reference numerals

R-1: a first coagulation vessel; r-2: a second coagulation vessel; r-3: a third coagulation kettle; p-1: a first coagulation kettle water colloidal particle pump; p-2: a second coagulation kettle water colloidal particle pump; p-3: a third coagulation kettle water colloidal particle pump; x-1: a first coalescer stripper gas filter; x-2: a second coagulation reactor stripping gas filter; x-3: a third coagulation reactor stripping gas filter; x-4: an ejector; x-5: a water-glue mixer; e-1: a circulating hot water heater; e-2: a glue solution heater; PS: isoprene rubber solution; HW: circulating hot water; HW-A: circulating hot water A; HW-B: circulating hot water B; LS: steam; LC: steam condensate water; WS: gas phase at the top of the kettle; WR: colloidal particle water.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.

In the present invention, the term "pressure" refers to gauge pressure.

The invention provides a method for coagulating an isoprene rubber solution, wherein the method comprises the following steps: the heterogeneous mixture is sequentially sent into a first condensation kettle, a second condensation kettle and a third condensation kettle to remove the solvent; and feeding the superheated water into a second condensation kettle from the bottom of the second condensation kettle, wherein the heterogeneous mixture is obtained by mixing the post-treatment circulating hot water A and an isoprene rubber solution.

According to the present invention, the method for mixing the post-treatment circulating hot water a and the isoprene rubber solution is not particularly limited as long as sufficient mixing is possible, and for example, the post-treatment circulating hot water a and the isoprene rubber solution may be mixed by introducing them into a mixer. As such a mixer, an SX type mixer may be used.

In the present invention, from the viewpoint of the particle size and size of isoprene rubber, it is preferable that the weight ratio of isoprene rubber contained in the isoprene rubber solution to the total amount of post-treatment circulating hot water a and B is from 0.025 to 0.075: 1, more preferably 0.03 to 0.06: 1.

specific examples of the weight ratio of isoprene rubber contained in the isoprene rubber solution to the total amount of post-treatment circulating hot water a and B include, for example, 0.025: 1. 0.03: 1. 0.035: 1. 0.04: 1. 0.045: 1. 0.05: 1. 0.055: 1. 0.06: 1. 0.065: 1. 0.07: 1 or 0.075: 1, etc.

According to the present invention, the heterogeneous mixture may be fed into the first coagulation vessel by various feeding methods generally employed in the art, and preferably, the heterogeneous mixture is fed into the first coagulation vessel through a nozzle.

In the invention, steam does not directly enter the second coagulation kettle, but exchanges heat with part of the post-treatment circulating hot water to change the post-treatment circulating hot water into superheated water to enter the second coagulation kettle, so that the coagulation effect of the second coagulation kettle is ensured, the external discharge of sewage is reduced, the environmental protection requirement is met, and the subsequent sewage treatment cost is reduced.

Preferably, the steam temperature is 125-200 ℃.

Preferably, the superheated water temperature is 125-145 ℃; more preferably, the superheated water temperature is 130-140 ℃.

Preferably, the first steam condensate water temperature is 140-200 ℃, and the pressure is 0.4-0.8 Mpa; more preferably, the first steam condensate water temperature is 140-160 ℃, and the pressure is 0.4-0.8 MPa.

Preferably, the temperature of the second steam condensate water is 85-125 ℃, and the pressure is 0.4-0.8 Mpa; more preferably, the second steam condensate temperature is 95-105 ℃ and the pressure is 0.4-0.8 Mpa.

According to the invention, the steam is converted into a first steam condensate after a first heat exchange with the post-treatment circulating hot water B, the first steam condensate has a high temperature, and the heat of the first steam condensate can be further recovered. Therefore, before the post-treatment circulating hot water a is mixed with the isoprene rubber solution, the first steam condensate is preferably subjected to second heat exchange with the isoprene rubber solution, so that the first steam condensate is further cooled to obtain a second steam condensate.

The first steam condensate water and the isoprene rubber solution are subjected to second heat exchange to form second steam condensate water, so that the temperature of the isoprene rubber solution can be increased while the temperature of the isoprene rubber solution is reduced, and the condensation effect of the first condensation kettle is improved.

The first heat exchange and the second heat exchange may be performed by using various heat exchangers generally used in the art, and for example, a shell-and-tube heat exchanger may be used.

According to the present invention, in view of controlling the particle size and size of isoprene rubber, it is preferable that the weight ratio of the post-treatment circulating hot water B to the post-treatment circulating hot water a is 0.15 to 0.4: 1; more preferably, the weight ratio of the post-treatment circulating hot water B to the post-treatment circulating hot water a is 0.15 to 0.3: 1; further preferably, the weight ratio of the post-treatment circulating hot water B to the post-treatment circulating hot water a is 0.2 to 0.3: 1.

according to the invention, preferably, the outlet gas phases at the top parts of the second condensation kettle and the third condensation kettle enter the bottom part of the first condensation kettle, and the solvent gas phase is evaporated out from the top part of the first condensation kettle, passes through a stripping gas filter and a condensing cooler and then enters the oil-water separation tank for layering; more preferably, the gas phase at the top outlet of the second coagulation kettle directly enters the bottom of the first coagulation kettle, the gas phase at the top outlet of the third coagulation kettle enters the bottom of the first coagulation kettle along with steam sprayed by the steam sprayer, and the solvent gas phase is finally evaporated from the top of the first coagulation kettle and enters the oil-water separation tank for separation after passing through the stripping gas filter and the condensing cooler.

According to the invention, the method for coagulating the isoprene rubber solution is carried out by adopting a three-kettle differential pressure coagulation process.

According to the present invention, the operating conditions of the first coagulation vessel may be various conditions commonly used in the art, and preferably, the operating pressure of the first coagulation vessel is 0.01 to 0.03MPa and the temperature is 80 to 90 ℃.

According to the present invention, the operating conditions of the second coagulation-up vessel may be various conditions commonly used in the art, and preferably, the operating pressure of the second coagulation-up vessel is 0.06-0.1MPa and the temperature is 100-120 ℃.

According to the present invention, the operating conditions of the third coagulation-up tank may be various conditions generally used in the art, and preferably, the operating pressure of the third coagulation-up tank is 0.004 to 0.006MPa and the temperature is 95 to 115 ℃.

According to the present invention, preferably, the method further comprises introducing steam into the bottom of the first coagulation reactor for adjusting the temperature of the first coagulation reactor. That is, the temperature compensation means for the first coagulation-flocculation vessel is not a continuous means of introducing steam into the bottom of the first coagulation-flocculation vessel, but a small amount of steam is introduced to return the temperature of the first coagulation-flocculation vessel to the above range when the temperature of the first coagulation-flocculation vessel decreases due to heat loss.

According to the present invention, preferably, the method further comprises introducing steam into the bottom of the second coagulation vessel for adjusting the temperature of the second coagulation vessel. That is, the temperature compensation of the second coagulation reactor is performed, and specifically, when the temperature of the second coagulation reactor is decreased by heat loss, the temperature of the first coagulation reactor is returned to the above range by introducing a small amount of steam, rather than continuously introducing steam into the bottom of the second coagulation reactor.

According to the invention, the isoprene rubber solution can be synthesized by adopting a method which is common in the field.

According to the present invention, the concentration of isoprene rubber in the isoprene rubber solution may be 12 to 25 wt%, more preferably 16 to 18 wt%, and particularly preferably 17 wt%.

In addition, the solvent in the isoprene rubber solution is preferably one or more of cyclohexane, hexane, pentane, methylcyclopentane, 3-methylpentane, heptane and octane.

The present invention will be described in detail below by way of examples, but the present invention is not limited to the following examples.

In the following examples and comparative examples, the post-treatment circulating hot water was desalted water.

Example 1

The condensation process of this embodiment adopts a differential pressure type, and a process flow diagram thereof is shown in fig. 1, an isoprene rubber solution PS (specifically, a rare earth isoprene rubber solution, a solvent of 65 wt% of hexane, 15 wt% of methylcyclopentane, 20 wt% of 3-methylpentane, hereinafter referred to as a glue solution) is sent to a glue solution heater E-2 to perform a second heat exchange with first steam condensate water, and then sent to a water-glue mixer X-5 to be mixed with fed post-treatment circulating hot water a to obtain a heterogeneous mixture, the obtained heterogeneous mixture is sent to a first condensation kettle R-1, and a kettle top gas phase WS passes through a first condensation kettle gas stripping filter X-1 and a condensation cooler and then enters an oil-water separation tank to be layered; in addition, feeding the post-treatment circulating hot water B into a circulating hot water heater E-1 to perform first heat exchange with the fed partial steam LS to obtain first steam condensate water and superheated water, and feeding the superheated water into a second condensation kettle R-2 from the bottom of the second condensation kettle R-2; colloidal particle water WR at the bottom of a first condensation kettle R-1 is sent into a second condensation kettle R-2 through a first condensation kettle colloidal particle pump P-1, colloidal particle water WR at the bottom of a second condensation kettle R-2 is sent into a third condensation kettle R-3 through a second condensation kettle colloidal particle pump P-2, gas phase WS at the top of the second condensation kettle R-2 directly enters the bottom of the first condensation kettle R-1, gas phase WS at the top of the third condensation kettle R-3 enters the bottom of the first condensation kettle R-1 along with steam sprayed by a steam sprayer X-4, and solvent gas phase is finally steamed out from the top of the first condensation kettle R-1 and enters an oil-water layering tank for layering after passing through a steam stripping gas filter X-1 and a condensation cooler. And (2) sending the colloidal particle water WR at the bottom of the third coagulation reactor R-3 to a post-treatment working section through a third coagulation reactor colloidal particle pump P-3 for dehydration, drying and packaging treatment, and in addition, when the temperature of the first coagulation reactor R-1 and the second coagulation reactor R-2 is lower than the preset temperature, respectively sending a small amount of steam LS from the bottom of the first coagulation reactor R-1 and the bottom of the second coagulation reactor R-2 for regulating the temperature of the first coagulation reactor R-1 and the second coagulation reactor R-2 (namely, taking temperature compensation measures for the first coagulation reactor R-1 and the second coagulation reactor R-2).

Wherein, the three-kettle condensation process conditions are as follows: the top pressure of the first coagulation reactor is 0.03MPa, the top pressure of the second coagulation reactor is 0.08MPa, and the top pressure of the third coagulation reactor is 0.005 MPa; the temperature of the bottom of the first coagulation kettle is 88 ℃, the temperature of the bottom of the second coagulation kettle is 104 ℃, and the temperature of the bottom of the third coagulation kettle is 100 ℃; the temperature of the glue solution is 80 ℃; circulating hot water at 96 ℃; the steam temperature is 200 ℃, and the pressure is 0.45 MPa; the temperature of the first steam condensate water is 160 ℃, the pressure is 0.45MPa, the temperature of the second steam condensate water is 95 ℃, and the pressure is 0.44 MPa. The circulating hot water B/A is 0.2 (weight ratio); the concentration of the glue solution is 17 weight percent, the weight ratio of the rubber contained in the glue solution to the total amount of the post-treatment circulating hot water A and the post-treatment circulating hot water B is 0.03: 1.

the results are shown in Table 1.

Example 2

The B/A ratio of the circulating hot water is 0.15, the other process conditions are the same as example 1, and the experimental results are shown in Table 1.

Example 3

The B/A ratio of the circulating hot water is 0.3, other process conditions are the same as example 1, and the experimental results are shown in Table 1.

Comparative example 1

The process flow chart is shown in figure 2, all the post-treatment circulating hot water A and B and the rare earth isoprene rubber solution are mixed and enter a first condensation kettle R-1, steam which exchanges heat with the post-treatment circulating hot water B directly enters a second condensation kettle R-2, other process conditions are the same as those in example 1, and the experimental results are shown in table 1.

TABLE 1

Note 1: in actual production, the physical properties of the condensed glue solution of each batch in a production cycle are slightly different, so that the data in the table fluctuates within a certain range, and the values given in the table are all mean values in a production cycle.

Note 2: in the production process, the third condensation kettle does not adopt temperature compensation measures, namely, steam is not generally introduced.

Note 3: in the production, after the steam enters the condensation process, except that a part of the steam is used as the supplement of the consumption of the circulating hot water in the post-treatment process, other parts of the steam are finally changed into sewage and discharged to a sewage treatment system.

Note 4: the total amount of steam introduced into the three condensation kettles (the steam amount of the first kettle, the steam amount of the second kettle and the steam amount of the ejector) is the circulating hot water consumption amount and the sewage discharge amount of the post-treatment procedure

Note 5: various cost calculation bases in implementation effects are as follows: steam is 350 yuan/ton; 17 yuan/ton of condensed water; the sewage treatment cost is 7 yuan/ton.

As can be seen from table 1, in example 1 compared to comparative example 1, the steam was not directly fed into the second coagulation vessel, i.e.: the steam consumption is increased by 0.3t/h, namely the steam consumption per ton of product is increased by 0.07 ton of steam, and the cost is increased by 24.5 yuan per ton (product); the discharged sewage is reduced by 8.4t/h and 77%, and the cost is saved by 13.7 yuan/ton (product); the steam condensed water can be utilized to increase 8.7t/h, the cost is saved by 34.6 yuan/ton (product), the total cost is saved by 23.8 yuan/ton (product), and the cost is saved by 71.4 yuan per 3 ten thousand tons/year. (the steam dosage is slightly increased, the operation cost is neglected)

Social benefits are as follows: calculated according to the annual output of 3 ten thousand tons, the sewage discharge is reduced by 5.9 ten thousand tons per year.

Compared with the comparative example 1, the effects of the examples 2 and 3 are the same as those of the example 1, the change of the B/A value of the circulating hot water has certain influence on the temperature of the second condensation kettle, but the temperature of the second condensation kettle fluctuates in a smaller range through the adjustment of the heat exchanger.

The agglomeration method of the present invention can be seen from the comparison of examples and comparative examples, and its significant effects include:

1. on the premise that all indexes of the product are qualified, the total steam consumption is not increased or slightly increased, a large amount of reusable steam condensate is obtained, the cost is saved, and the economic benefit is increased.

2. The sewage discharge amount is obviously reduced, and the social benefit is obtained while the economic benefit is increased.

3. High-temperature sewage can not directly enter a sewage treatment plant, and needs to be subjected to cooling pretreatment, so that the sewage discharge amount is reduced, and the cooling water consumption amount can be reduced.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for coagulating an isoprene rubber solution, the method comprising: feeding the heterogeneous mixture into a first condensation kettle, a second condensation kettle and a third condensation kettle in sequence to remove the solvent; the method comprises the steps of carrying out first heat exchange on post-treatment circulating hot water B and steam to obtain superheated water and first steam condensate water, sending the superheated water into a second condensation kettle from the bottom of the second condensation kettle, mixing post-treatment circulating hot water A with an isoprene rubber solution to obtain a heterogeneous mixture, carrying out second heat exchange on the first steam condensate water and the isoprene rubber solution before mixing the post-treatment circulating hot water A with the isoprene rubber solution to further cool the first steam condensate water to obtain second steam condensate water, wherein the temperature of the superheated water is 125-145 ℃.

2. The method of claim 1, wherein the method is performed using a three-pot differential pressure coagulation process.

3. The method as claimed in claim 1 wherein the steam temperature is 125-200 ℃.

4. The process according to any one of claims 1 to 3, wherein the weight ratio of the isoprene rubber contained in the isoprene rubber solution to the total amount of post-treatment recycled hot water A and B is from 0.025 to 0.075: 1.

5. the method as claimed in claim 1, wherein the first steam condensate temperature is 140-200 ℃ and the pressure is 0.4-0.8MPa, and the second steam condensate temperature is 85-125 ℃ and the pressure is 0.4-0.8 MPa.

6. A method according to any one of claims 1-3, wherein the weight ratio of the post-treatment recycled hot water B to the post-treatment recycled hot water a is 0.15-0.4: 1.

7. the method according to any one of claims 1 to 3, wherein the outlet gas phase at the top of the second coagulation vessel and the outlet gas phase at the top of the third coagulation vessel enter the bottom of the first coagulation vessel, and the solvent gas phase is distilled out from the top of the first coagulation vessel and enters the oil-water separation layer tank for separation after passing through a stripping gas filter and a condensing cooler.

8. A process according to any one of claims 1 to 3, wherein the operating pressure of the first coagulation vessel is in the range of from 0.01 to 0.03MPa and the temperature is in the range of from 80 to 90 ℃.

9. The process as claimed in any one of claims 1 to 3, wherein the operating pressure of the second coagulation vessel is from 0.06 to 0.1MPa and the temperature is from 100 ℃ to 120 ℃.

10. A process according to any one of claims 1 to 3, wherein the third coagulation vessel is operated at a pressure of from 0.004 to 0.006MPa and a temperature of from 95 to 115 ℃.

11. The method according to any one of claims 1 to 3, wherein the isoprene rubber solution is a rare earth isoprene rubber solution.