KR102535166B1 - Solvent recovery method and solvent recovery apparatus - Google Patents

Abstract

The present invention relates to a method for recovering a solvent, and more particularly, supplying a polymerization reaction product containing at least one monomer and a solvent to a reactor to obtain a polymer solution (S10); supplying the stream containing the polymer solution to a separator to separate an upper discharge stream containing a solvent in a vapor phase and a lower discharge stream containing a polymer solution (S20); and heating a branched stream obtained by branching a portion of the bottom discharge stream of the separator with a heating device, returning the stream to the separator, and supplying the remaining stream including the remainder of the bottom discharge stream of the separator to a steam stripping unit (S30). It provides a solvent recovery method in which the vapor ratio of the branched stream, which is heated by the heating device and then returned to the separator, is controlled by a pressure control valve.

Description

Solvent recovery method and recovery device {SOLVENT RECOVERY METHOD AND SOLVENT RECOVERY APPARATUS}

The present invention relates to a method and apparatus for recovering a solvent, and more particularly, to a method and apparatus for recovering a solvent from a polymer solution prepared by solution polymerization.

Solution polymerization is a method of dissolving monomers in an appropriate solvent and polymerizing them in a solution state, and is used for radical polymerization and ionic polymerization. A representative example of preparing a polymer through solution polymerization is the preparation of a styrene-butadiene copolymer by anionic polymerization of styrene and butadiene. As an anionic polymerization initiator, n-butyl lithium is usually used, and cyclohexane is used as a solvent.

As such, after the anionic polymerization is completed, a polymer solution in which the polymer is dissolved or dispersed in a solvent is obtained. In order to obtain a solid polymer product, the following process of recovering the solvent in the polymer solution is essentially performed. After the polymerization is completed, the polymer solution is transferred to a vacuum blowdown tank, and some solvent is recovered as a gas using the residual heat of the polymerization reaction. The polymer solution having an increased composition of the polymer is transferred to the steam stripping process unit, and in the steam stripping process unit, residual solvent in the polymer is minimized by directly contacting steam to recover the solvent as a gas. The polymer obtained as a solid through steam stripping is transported together with water to the production process and can be obtained as pellets.

However, in the steam stripping process, a large amount of steam is input, consuming the most energy among the polymer manufacturing processes. The amount of steam input depends on the amount of solvent introduced into the steam stripping process. If the amount of steam is insufficient, the amount of residual solvent in the polymer increases, increasing the cost of gas solvent treatment in the subsequent productization process, and tVOC (total There was a problem adversely affecting the product, such as an increase in Volatile Organic Compound).

KR 2013-0048519 A

The problem to be solved in the present invention is to reduce the energy used during the polymer manufacturing process while minimizing the residual solvent flowing into the product production process in order to solve the problems mentioned in the background technology of the above invention. .

That is, the present invention reduces the amount of steam used in the steam stripping process by volatilizing the solvent in the polymer solution using a separator and a heating device before the steam stripping process of the polymer solution, thereby minimizing the residual solvent flowing into the product production process, The energy used during the polymer manufacturing process is to be provided with a solvent recovery method and recovery device that is reduced.

According to one embodiment of the present invention for solving the above problems, the present invention provides a polymerization reaction product containing one or more monomers and a solvent to a reactor to obtain a polymer solution (S10); supplying the stream containing the polymer solution to a separator to separate an upper discharge stream containing a solvent in a vapor phase and a lower discharge stream containing a polymer solution (S20); and heating a branched stream obtained by branching a portion of the bottom discharge stream of the separator with a heating device, returning the stream to the separator, and supplying the remaining stream including the remainder of the bottom discharge stream of the separator to a steam stripping unit (S30). It provides a solvent recovery method in which the vapor ratio of the branched stream, which is heated by the heating device and then returned to the separator, is controlled by a pressure control valve.

In addition, the present invention is a reactor to which a polymerization reaction product containing one or more monomers and a solvent is supplied, and discharges a stream containing a polymer solution obtained through polymerization of the polymerization reaction product; a separator receiving the discharge stream of the reactor and discharging an upper discharge stream containing a solvent in a vapor phase and a lower discharge stream containing a polymer solution; a heating device which heats a branched stream obtained by branching a part of the lower discharge stream of the separator and refluxes it to the separator; a pressure control valve for controlling a vapor ratio of the branched stream that is heated by the heating device and then returned to the separator; and a steam stripping unit receiving the remaining stream including the remaining portion of the lower discharge stream of the separator and volatilizing the solvent in the polymer solution.

The solvent recovery method and recovery device according to the present invention can reduce the amount of steam used in the steam stripping process by volatilizing the solvent in the polymer solution using a separator and a heating device before the steam stripping process of the polymer solution, thereby reducing the production process It is possible to provide a solvent recovery method and recovery device that minimizes the residual solvent flowing into the polymer while reducing the energy used during the polymer manufacturing process.

1 is a process flow diagram showing a method for recovering a solvent according to an embodiment of the present invention.
Figure 2 is a process flow chart according to the recovery method of the solvent according to Comparative Example 1 of the present invention.
3 is a process flow diagram showing a solvent recovery method according to Comparative Example 2 of the present invention.

The terms or words used in the description and claims of the present invention should not be construed as being limited to ordinary or dictionary meanings, and the inventors use the concept of terms appropriately to describe their invention in the best way. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical spirit of the present invention.

In the present invention, the term "upper" refers to a portion corresponding to a height of 50% or more from the total height of the device in the container, and "lower" refers to a portion corresponding to a height of less than 50% from the total height of the container or device. can

In the present invention, the term 'stream' may refer to a flow of a fluid in a process, or may also refer to a fluid itself flowing in a pipe. Specifically, the 'stream' may mean a fluid itself and a flow of the fluid flowing in a pipe connecting each device at the same time. Also, the fluid may mean gas or liquid.

Hereinafter, the present invention will be described in more detail with reference to FIG. 1 to aid understanding of the present invention.

According to the present invention, a method for recovering a solvent is provided. The recovery method of the solvent may include supplying a polymerization reaction product including one or more monomers and a solvent to the reactor 100 to obtain a polymer solution (S10); supplying the stream containing the polymer solution to the separator 200 to separate an upper discharge stream containing a solvent as a vapor phase and a lower discharge stream containing the polymer solution (S20); and a portion of the lower discharge stream of the separator 200, which is heated by a heater 220 and then refluxed to the separator 200, and the remainder including the remainder of the lower discharge stream of the separator 200. It includes supplying the stream to the steam stripping process unit 300 (S30), and the branch stream heated by the heating device 220 and then returned to the separator 200 is steam by the pressure control valve 230 Proportion can be adjusted.

According to an embodiment of the present invention, the step (S10) supplies a polymerization reaction product including one or more monomers and a solvent to the reactor 100, and includes a polymer formed by polymerization of the one or more monomers in the solvent. It may be a step of obtaining a polymer solution that For commercialization of the obtained polymer solution, a solid polymer may be obtained by performing solvent recovery steps described later.

The at least one monomer may be styrene, alphamethylstyrene, 3-methylstyrene, 4-methylstyrene, 4-propylstyrene, isopropenylnaphthalene, 1-vinylnaphthalene, or an alkyl group having 1 to 3 carbon atoms substituted. An aromatic vinyl-based monomer containing at least one member selected from the group consisting of styrene, 4-cyclohexyl styrene, 4-(p-methylphenyl)styrene, and halogen-substituted styrene; and 1,3-butadiene, 1,4-butadiene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, 1,3-pentadiene, piperylene, 3-butyl-1 It may include, but is not limited to, a conjugated diene-based monomer including at least one selected from the group consisting of 3-octadiene, 2-phenyl-1,3-butadiene and isoprene. As a specific example, the one or more monomers may include styrene and butadiene, and thus the polymer produced by the polymerization reaction may be a styrene-butadiene copolymer.

The solvent is cyclohexane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-ε caprolactam , 1,3-dialkyl-2-imidazolidinone, tetramethyl urea, and hexamethylphosphate triamide. As a specific example, the organic solvent may include cyclohexane. In this case, polymerization of the styrene-butadiene copolymer can be easily performed.

The polymerization reaction may be carried out by further including additives such as ion-exchanged water, an initiator, a molecular weight regulator, an activator, and a redox catalyst.

The initiator is, for example, t-butyl lithium, diisopropylbenzene hydroperoxide, t-butyl hydroperoxide, cumene hydroperoxide, p-menthane hydroperoxide, di-t-butyl peroxide, t-butyl One selected from the group consisting of cumyl peroxide, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, dibenzoyl peroxide, 3,5,5-trimethylhexanol peroxide and t-butyl peroxy isobutylate may contain more than

The molecular weight modifier is, for example, a-methylstyrenedimer, t-dodecylmercaptan, n-dodecylmercaptan, octylmercaptan, carbon tetrachloride, methylene chloride, methylene bromide, tetraethyl diuram disulfide, dipentamethylene diuram disulfide And at least one selected from the group consisting of diisopropylxantogen disulfide may be used.

The activator is, for example, one selected from the group consisting of sodium hydrosulfite, sodium formaldehyde sulfoxylate, sodium ethylenediamine tetraacetate, ferrous sulfate, lactose, dextrose, sodium linolenate, and sodium sulfate more can be used.

As the redox catalyst, for example, at least one selected from the group consisting of sodium formaldehyde sulfoxylate, ferrous sulfate, disodium ethylenediaminetetraacetate, and copper sulfate may be used.

It is not limited to the types of the above additives, and commonly used additives for polymerization may be additionally used. As a specific example, n-butyl lithium may be used as the initiator. In this case, polymerization of the styrene-butadiene copolymer can be easily performed.

According to one embodiment of the present invention, in addition to the above composition, an activator, a chelating agent, a dispersing agent, a pH adjusting agent, a deoxidizing agent, a particle size adjusting agent, an antiaging agent, an antioxidant, and an antifoaming agent within a range that does not degrade the physical properties of the copolymer as necessary. And additives such as an oxygen scavenger may be additionally added.

According to an embodiment of the present invention, after the step (S10) and before the step (S20) described below, the polymer solution is supplied to a blow down tank (not shown) and the residual heat of the polymerization reaction is used. Thus, a step of discharging the solvent into a vapor phase may be further included. Since residual heat of the polymerization reaction remains in the polymer solution supplied to the blowdown tank (not shown), the solvent in the polymer solution is recovered as a gaseous phase under reduced pressure conditions in which no steam is supplied in the blowdown tank (not shown). can do. The recovered solvent is supplied to a purification unit (not shown), and the polymer solution from which some solvent is removed is discharged to the bottom, and the following steps may be performed to additionally recover the solvent.

Conventionally, a polymer solution from which some solvent has been removed, discharged from a blowdown tank (not shown), is directly supplied to the steam stripping process unit 300 to recover the solvent in contact with steam in the gas phase, thereby obtaining a solid polymer. performed. However, in this case, a large amount of steam is input in the steam stripping process unit 300, resulting in high energy consumption. The amount of steam injected into the steam stripping process unit 300 depends on the amount of solvent in the polymer solution introduced into the steam stripping process unit 300, and when the amount of steam input is insufficient, the amount of residual solvent in the solid polymer increases, , In the subsequent commercialization process, there were problems adversely affecting the product, such as an increase in cost due to vapor phase treatment of the solvent and an increase in tVOC (total volatile organic compound) of the polymer.

Accordingly, in the present invention, by volatilizing the solvent in the polymer solution using the separator 200 and the heating device 220 before the steam stripping process of the polymer solution, the residual solvent flowing into the subsequent product production process can be minimized, and the steam Since the amount of steam used in the stripping process unit 300 can be reduced, the energy used during the polymer manufacturing process can be reduced, and a solvent recovery method can be provided.

That is, according to the present invention, the discharge stream of the reactor 100 may be supplied to the separator 200, or the discharge stream of the reactor 100 may be supplied to the separator 200 after passing through a blowdown tank (not shown). can Specifically, in the present invention, the steps (S20) and (S30) may be performed after the step (S10).

According to one embodiment of the present invention, in the step (S20), the discharge stream of the reactor 100 containing the polymer solution is supplied to the separator 200, the upper discharge stream containing the solvent as a gas phase, and the polymer solution. It may be a step of separating a bottom discharge stream that As such, the polymer solution included in the discharge stream of the reactor 100 may be discharged as a polymer solution having a high polymer concentration in the lower discharge stream while passing through the separator 200 .

According to one embodiment of the present invention, the step (S30) is a step of supplying the bottom discharge stream of the separator 200 to the steam stripping process unit 300, and a part of the bottom discharge stream of the separator 200 is branched After heating the branched stream with a heating device 220, returning it to the separator 200, and supplying the remaining stream including the remainder of the lower discharge stream of the separator 200 to the steam stripping process unit 300. can do. In this case, the vapor mass fraction of the branched stream that is heated by the heating device 220 and then returned to the separator 200 may be controlled by the pressure control valve 230 . Specifically, the pressure control valve 230 controls the vapor of the branched stream until a branched stream branching off a portion of the lower discharge stream of the separator 200 is heated by the heating device 220 and then returned to the separator 200. It can play a role in adjusting the ratio. Here, the vapor ratio may refer to a weight ratio of vapor among liquid and vapor in a stream including liquid and vapor. That is, the vapor ratio of the branch stream from being heated by the heating device 220 to being refluxed by the separator 200 can be adjusted by adjusting the degree of opening and closing of the pressure control valve 230 .

More specifically, the pressure control valve 230 may adjust the vapor ratio of the branch stream from being heated by the heating device 220 until passing through the pressure control valve 230 . That is, the weight ratio of vapor among the liquid and vapor in the branch stream from being heated by the heating device 220 until passing through the pressure control valve 230 can be adjusted. At this time, the vapor ratio of the branch stream from being heated by the heating device 220 until passing through the pressure control valve 230 is 0 to 5% by weight and 0 to 2% by weight by the pressure control valve 230. , or 0% by weight. Within the vapor ratio range, the branch stream whose vapor ratio is adjusted exists in a liquid state containing a minimum amount of gas, so that the heat transfer efficiency is excellent and the solvent volatilization ability of the separator 200 can be improved. There is also an effect of preventing a fouling phenomenon in which the branch stream is vaporized and the heating device 220 is clogged.

In addition, the heating device 220 for heating the branch stream of the separator 200 may be a heat exchanger, that is, a reboiler.

High-temperature steam may be used as a heat source used in the heating device 220, and the branch stream of the separator 200 may be heated by obtaining heat from the steam. At this time, the separator 200 does not have a separate solvent volatilization function, and as the stream heated by passing through the heating device 220 is refluxed into the separator 200, the polymer present in the separator 200 The solvent may be volatilized by increasing the temperature of the solution. The vapor ratio of the branched stream may tend to increase in the pipe after passing through the pressure control valve 230 and inside the separator 200 . In this way, the branched stream having an increased steam ratio may be sprayed into the separator 200 while being refluxed into the separator 200, and thus heat evenly to the polymer solution present in the separator 200. can deliver.

The volatilized solvent is recovered and supplied to a purification unit (not shown), and the polymer solution having an increased polymer concentration is discharged to the bottom, and the following subsequent steps for additionally recovering the solvent may be performed.

According to one embodiment of the present invention, in the step (S30), the mass flow rate of the branched stream branched from the lower discharge stream of the separator and returned to the separator to the total flow rate of the lower discharge stream of the separator 200 is It may be 80 to 90%.

When the mass flow rate of the branch stream is 80% or more, the amount of residual solvent in the stream introduced into the subsequent steam stripping process unit 300 can be minimized, and finally a solid polymer product obtained with high purity can be obtained there is. On the other hand, when the mass flow rate of the branch stream is 90% or less, the temperature of the stream refluxed to the separator 200 is prevented from being excessively lowered, that is, the need for an excessive amount of steam in the heating device 220 can be prevented. . Therefore, by making it easy to volatilize the solvent in the polymer solution present in the separator 200, there is an effect of reducing the amount of steam consumed in the subsequent steam stripping process unit 300, and an excessive branch stream is removed from the separator By preventing the inflow and discharge into the 200, there is an effect of preventing fouling in the pipe caused by hydraulic pressure instability and differential pressure increase.

For example, the ratio may be 80 to 95%, 80 to 90%, 85 to 90%, or 88 to 90%. In the case of using cyclohexane as a solvent during the polymerization and using a phenol-based, sulfur-based, or phosphorus-based antioxidant as an additive, a branch stream passing through the heating device 220 and refluxing to the separator 200 within this range By preventing the temperature of the excessive decrease, the antioxidant function can be easily exhibited in the solvent. Accordingly, it is possible to obtain a high-purity product of excellent quality by preventing color change of the finally obtained solid polymer.

The antioxidant is a specific example, butylated hydroxyl toluene, tris (nonylphenyl) phosphite (tris (nonylphenyl) phosphite), N, N'-1,6-hexanedyl bis [3,5 -bis(1,1-dimethylethyl)-4-hydroxyphenylpropanamide) (N,N'-1,6-hexanediylbis[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenylpropanaimd]) And octadecyl-3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionate (octadecyl-3- [3,5-di-tert-butyl-4-hydroxyphenyl] propionate) It may be one or more selected from the group.

According to one embodiment of the present invention, in the step (S30), the polymer concentration of the polymer solution in the lower discharge stream of the separator 200 supplied to the steam stripping process unit 300 is 20 to 40% by weight, 30 to 40% by weight 40 wt%, or 35 to 40 wt%. That is, the polymer concentration of the polymer solution in the residual stream of the separator 200 supplied to the steam stripping process unit 300 is 20 to 40% by weight, 30 to 40% by weight, or 35 to 40% by weight can be

When the polymer concentration of the polymer solution is 20% by weight or more, the amount of solvent in the polymer solution in the stream supplied to the steam stripping process unit 300 can be minimized, so that the finally obtained solid polymer product can be obtained with high purity, There is an effect of reducing the amount of steam consumed in the subsequent steam stripping process unit 300. On the other hand, when the polymer concentration of the polymer solution is 40% by weight or less, the heating device 220, the piping connecting the heating device 220 and the separator 200, and the fouling due to polymer precipitation in the steam stripping process unit 300 Since fouling can be prevented, heat exchange efficiency and solvent recovery efficiency are excellent.

As a specific example, for the mass flow rate of the solvent contained in the polymer solution in the discharge stream of the reactor 100 (when passing through the blowdown tank, the discharge stream at the bottom of the blowdown tank) to have the polymer concentration range of the polymer solution, The mass flow rate of steam supplied to the heating device 220 may be 0.005 to 0.110, 0.017 to 0.110, or 0.052 to 0.110, and within this range, the polymer concentration of the polymer solution can be easily adjusted within the above range. .

According to one embodiment of the present invention, in the step (S30), the viscosity of the polymer solution in the lower discharge stream of the separator 200 supplied to the steam stripping process unit 300 is 1,000 to 10,000 cp, 1,000 to 8,000 cp , or 1,000 to 5,000 cp. That is, the viscosity of the polymer solution in the residual stream of the separator supplied to the steam stripping process is 1,000 to 10,000 cp, 1,000 to 8,000 cp, or 1,000 to 5,000 cp can be

When the viscosity of the polymer solution is 1,000 cp or more, the amount of solvent in the polymer solution in the stream supplied to the steam stripping process unit 300 can be minimized, so that the finally obtained solid polymer product can be obtained with high purity, while subsequent There is an effect of reducing the amount of steam consumed in the steam stripping process unit 300. On the other hand, when the viscosity of the polymer solution is 10,000 cp or less, the heating device 220, the piping connecting the heating device 220 and the separator 200, and the fouling due to polymer accumulation in the steam stripping process unit 300 ( The fouling phenomenon can be prevented, and thus there is an effect of preventing the operation of the separator 200 from being shut down.

For example, when the viscosity of the polymer solution in the discharge stream of the reactor 100 supplied to the separator 200 is 100 to 1,000 cp, the solvent is volatilized from the separator 200 and then to the lower part of the separator 200 The polymer concentration of the polymer solution in the discharged bottom discharge stream may be 20 to 40% by weight, and the viscosity of the polymer solution may be 1,000 to 10,000 cp. At this time, assuming that the inside of the separator 200 maintains a steady state, the polymer concentration of the polymer solution contained in the separator 200 and the polymer solution included in the lower discharge stream of the separator 200 and viscosity may be the same.

On the other hand, for example, when the stream containing the polymer solution discharged from the reactor 100 is supplied to a conventional distillation tower instead of the separator 200 according to the present invention, a polymer having a polymer concentration or viscosity within the above range It may not be easy to drain the solution. Even if the distillation column is used to discharge a polymer solution having a polymer concentration or viscosity in the above range by solvent volatilization, due to the complex internal structure of a conventional distillation column having a tray or a packed bed When a fouling phenomenon occurs due to polymer precipitation or accumulation, the flow of the polymer solution is not smooth, and the residence time is locally different, resulting in a decrease in heat transfer efficiency. Accordingly, physical properties of the polymer in the discharged polymer solution may also be adversely affected.

As such, when the stream containing the polymer solution discharged from the reactor 100 is supplied to a conventional distillation tower instead of the separator 200 according to the present invention to volatilize the solvent in the polymer solution, as described above, the distillation tower Since a number of problems are caused by the fouling phenomenon due to precipitation or accumulation of polymers due to the complicated internal structure, when the bottom discharge stream of the distillation column is refluxed, the pressure control valve 230 is used to reflux the bottom discharge stream. Even if the vapor ratio is adjusted, similar or identical effects to those of the present invention may not be obtained.

According to one embodiment of the present invention, in the step (S30), the temperature of the branch stream heated by the heating device 220 and refluxed to the separator 200 may be 80 to 110 °C.

When the temperature of the reflux stream is 80° C. or higher, the temperature of the branch stream refluxed to the separator 200 is prevented from being excessively lowered so that the solvent in the polymer solution present in the separator 200 is easily evaporated. By doing so, there is an effect of reducing the amount of steam consumed in the subsequent steam stripping process unit 300. On the other hand, when the temperature of the refluxing branch stream is 110 ° C. or lower, the amount of residual solvent in the stream introduced into the subsequent steam stripping process unit 300 can be minimized, thereby producing a finally obtained solid polymer product with high purity. There is an effect that can be obtained.

For example, the temperature of the refluxing branch stream may be 80 to 110 °C, 85 to 105 °C, or 90 to 100 °C. In the case of using cyclohexane as a solvent during the polymerization and using a phenol-based, sulfur-based, or phosphorus-based antioxidant as an additive, within this range, the branch stream passing through the heating device 220 and refluxing to the separator 200 By preventing the temperature from excessively lowering, the antioxidant function can be easily exhibited in the solvent. Accordingly, it is possible to obtain a high-purity product of excellent quality by preventing color change of the finally obtained solid polymer.

According to an embodiment of the present invention, after the step (S30), volatilizing the solvent from the remaining stream of the separator 200 supplied to the steam stripping process unit 300 to obtain a solid polymer (S40) may further include. As described above, in the present invention, before supplying the discharge stream of the reactor 100 to the stripping process unit 300, the discharge stream of the reactor 100 is passed through the separator 200 and the heating device 220 to obtain polymer By volatilizing the solvent in the solution, the amount of steam used in the steam stripping process unit 300 can be reduced, and as a result, the total amount of energy used in the process can be reduced. The solvent volatilized and recovered in the stripping process unit 300 is supplied to a purification unit (not shown), and the stream containing the solid polymer is discharged to the bottom to perform the following steps to additionally recover the solvent can do.

According to one embodiment of the present invention, the method for recovering the solvent according to the present invention is to discharge the residual solvent by introducing the lower discharge stream of the steam stripping process unit 300 containing the solid polymer into a dryer in the product manufacturing process A step (S50) may be further included. As a specific example, circulating water (water) for transporting the solid polymer is circulated in the steam stripping process unit 300, and the lower discharge stream of the steam stripping process unit 300 containing the solid polymer and the circulating water into a dryer in the product manufacturing process, residual solvent and moisture can be discharged and disposed of as waste gas, and a final solid polymer product can be obtained.

According to the present invention, an apparatus for recovering a solvent is provided. The solvent recovery device includes a reactor 100 supplying a polymerization reaction product including one or more monomers and a solvent and discharging a stream containing a polymer solution obtained through polymerization of the polymerization reaction product; a separator 200 that receives the discharge stream of the reactor and discharges an upper discharge stream containing a solvent in a gas phase and a lower discharge stream containing a polymer solution; a heating device 220 which heats a branched stream obtained by branching a part of the lower discharge stream of the separator 200 and refluxes it to the separator 200; a pressure control valve (230) for controlling a vapor ratio of the branched stream that is heated by the heating device and then returned to the separator; and a steam stripping unit 300 receiving a residual stream including the remainder of the lower discharge stream of the separator 200 and volatilizing the solvent in the polymer solution.

According to one embodiment of the present invention, the solvent recovery device according to the present invention may be a device for performing a process according to the solvent recovery method described above.

According to one embodiment of the present invention, the solvent recovery device according to the present invention can be described with reference to FIG. 1 below. Specifically, the solvent recovery device may include a reactor 100, a separator 200, a heating device 220, a pressure control valve 230, and a steam stripping process unit 300.

According to an embodiment of the present invention, the reactor 100 receives a polymerization reaction product including one or more monomers and a solvent to obtain a polymer solution including a polymer formed by polymerization of one or more monomers in the solvent. can

The one or more monomers and types of the solvent may be the same as the types of monomers and solvents used in the solvent recovery method described above.

The polymerization reaction may be carried out by further including ion-exchanged water, an initiator, a molecular weight regulator, an activator, a redox catalyst, and other additives. The type of the additive may be the same as the type of additive used in the solvent recovery method described above.

According to one embodiment of the present invention, the solvent recovery device according to the present invention receives the discharge stream of the reactor 100, discharges the solvent into the gas phase using the residual heat of the polymerization reaction, and the lower part containing the polymer solution A blowdown tank (not shown) may be further included to discharge the exhaust stream to the separator 200 . Since residual heat of the polymerization reaction remains in the polymer solution supplied to the blowdown tank (not shown), the solvent in the polymer solution is recovered as a gaseous phase under reduced pressure conditions in which no steam is supplied in the blowdown tank (not shown). can do. The recovered solvent may be supplied to a purification unit (not shown), and the polymer solution from which some of the solvent is removed may be discharged to a lower portion and supplied to a device for additionally recovering the solvent.

That is, according to the present invention, the discharge stream of the reactor 100 may be supplied to the separator 200, or the discharge stream of the reactor 100 may be supplied to the separator 200 after passing through a blowdown tank (not shown). can

According to an embodiment of the present invention, the separator 200 may receive the discharge stream of the reactor and discharge an upper discharge stream including a solvent in a vapor phase and a lower discharge stream including a polymer solution. As such, the polymer solution included in the discharge stream of the reactor 100 may be discharged as a polymer solution having a high polymer concentration in the lower discharge stream while passing through the separator 200 .

According to an embodiment of the present invention, the heating device 220 may heat a branched stream obtained by branching a part of the lower discharge stream of the separator 200 and reflux it to the separator. Specifically, in the present invention, in the process of supplying the lower discharge stream of the separator 200 to the subsequent steam stripping process unit 300, a portion of the lower discharge stream of the separator 200 is branched and heated by the heating device 220 After that, the separator may be refluxed, and the remaining stream including the remainder of the lower discharge stream of the separator may be supplied to the steam stripping process unit 300. At this time, the heating device 220 may be a heat exchanger, that is, a reboiler.

High-temperature steam may be used as a heat source used in the heating device 220, and branched streams among discharged streams at the bottom of the separator 200 may be heated by obtaining heat from the steam. As a result, the branched stream of the lower discharge stream of the separator 200 passes through the heating device 220 and is refluxed to the separator 200 in a heated state, so that the solvent contained in the polymer solution inside the separator 200 volatilizes. It can be.

The vapor ratio of the branched stream that is heated by the heating device 220 and then returned to the separator 200 may be adjusted by the pressure control valve 230 . Specifically, the pressure regulating valve 230 is a branch stream from which a part of the lower discharge stream of the separator 300 is heated by the heating device 220 until it passes through the pressure regulating valve 230. It can serve to regulate the vapor ratio of the stream.

According to one embodiment of the present invention, the steam stripping process unit 300 receives a residual stream including the remainder of the lower discharge stream of the separator 200, and volatilizes the solvent in the polymer solution to obtain a solid polymer can do. As described above, in the present invention, before supplying the discharge stream of the reactor 100 to the stripping process unit 300, the discharge stream of the reactor 100 passes through the separator 200 and the heating device 220 to remove the solvent By volatilizing, the amount of steam used in the steam stripping process unit 300 can be reduced, and as a result, the total amount of energy used in the process can be reduced.

According to an embodiment of the present invention, the solvent recovery device according to the present invention is a dryer (not shown) that receives the lower discharge stream of the steam stripping process unit 300 containing the solid polymer and discharges residual solvent. can include The dryer (not shown) may be included in a commercialization process (not shown). As a specific example, circulating water (water) for transporting the solid polymer is circulated in the steam stripping process unit 300, and the discharge stream of the steam stripping process unit 300 containing the solid polymer and the circulating water are commercialized By putting it into a dryer in the process, residual solvent and moisture can be discharged and disposed of as waste gas, and a final solid polymer product can be obtained.

According to an embodiment of the present invention, the solvent recovery device according to the present invention includes the reactor 100, a blowdown tank (not shown), a separator 200, a heating device 220, a pressure control valve 230, steam A pipe connecting between the stripping process unit 300 and a dryer (not shown) in the commercialization process may be provided, and in order to easily supply the lower discharge stream of each configuration to the configuration of the subsequent device, a pump is installed on the pipe (110, 210 or not shown) may be further provided.

According to an embodiment of the present invention, the solvent recovery device according to the present invention may include at least one or more of the separator 200, the pump 210, the heating device 220, and the pressure control valve 230. .

According to one embodiment of the present invention, in the solvent recovery method and recovery device according to the present invention, if necessary, a distillation column (not shown), a condenser (not shown), a reboiler (not shown), a pump (not shown), A compressor (not shown), a mixer (not shown), and a separator (not shown) may be additionally installed.

Above, the solvent recovery method and recovery device according to the present invention have been shown in the description and drawings, but the illustrations in the description and drawings describe and illustrate only the essential components for understanding the present invention, and the description and drawings In addition to the illustrated processes and devices, processes and devices not separately described or illustrated may be appropriately applied and used to implement the solvent recovery method and recovery device according to the present invention.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are intended to illustrate the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and the scope of the present invention is not limited only to these.

< Example >

Example One

As shown in the process flow chart shown in FIG. 1, styrene monomer, butadiene monomer, cyclohexane as a solvent and n-butyllithium as an initiator are supplied to the reactor 100 composed of a stirrer and a jacket, and polymerization is performed to obtain a polymer solution after polymerization. obtained. At this time, the polymer concentration in the polymer solution was 20% by weight (5 tons of polymer, 20 tons of solvent). Then, the stream containing the polymer solution is supplied from the reactor 100 to a blowdown tank (not shown) to recover some solvent in the gas phase under reduced pressure using residual heat remaining in the polymer solution, and polymer from which some solvent has been removed. solution was drained. At this time, the amount of some of the solvent recovered in the gaseous phase was 2.8 tons, and the concentration of the polymer solution from which some of the solvent was removed was 22.5% by weight. Then, the stream containing the polymer solution from which some of the solvent has been removed from the blowdown tank (not shown) is transferred to the separator 200 connected to the discharge line of the blowdown tank (not shown) through a pump (not shown). The solvent was further volatilized to obtain a polymer solution having a high polymer concentration. At this time, in the additional volatilization of the solvent in the separator 200, a branch stream obtained by branching 80% of the lower discharge stream of the separator 200 containing a polymer solution having a high polymer concentration is heated by the heat exchanger 220. After refluxing to the separator 200, the remaining stream including the remainder of the lower discharge stream of the separator 200 was supplied to the stripping process unit 300, and after being heated by the heat exchanger 220, the pressure The vapor ratio of the branch stream before passing through the control valve 230 was adjusted to 0% by weight using the pressure control valve 230. At this time, the amount of steam supplied to the heat exchanger 220 was 0.3 ton. , the amount of the additionally volatilized solvent was 2.2 tons, and the concentration of the polymer solution with an increased polymer concentration was 25.0% by weight.

Then, the residual stream containing the polymer solution having a high polymer concentration was transferred to the steam stripping process unit 300 to recover steam and solvent in the gas phase through direct steam contact, and obtain a solid polymer. At this time, the amount of steam used in the steam stripping process unit 300 was 12.0 tons. Then, together with the circulating water (water) present for transporting the solid polymer in the steam stripping process unit 300, the solid polymer is put into a dryer (not shown) in the product manufacturing process, and residual solvent and moisture are discharged as waste gas and discarded, and a final solid polymer product was obtained. At this time, the residual solvent in the solid polymer introduced into the dryer (not shown) in the product manufacturing process was 0.5% by weight.

Example 2

In Example 1, the process was simulated in the same manner as in Example 1, except that 0.9 tons of steam was supplied to the heat exchanger 220.

Example 3

In Example 1, the process was simulated in the same manner as in Example 1, except that 1.3 tons of steam was supplied to the heat exchanger 220.

Example 4

In Example 1, the process was simulated in the same manner as in Example 1, except that 1.7 tons of steam was supplied to the heat exchanger 220.

Example 5

In Example 1, the process was simulated in the same manner as in Example 1, except that 1.9 tons of steam was supplied to the heat exchanger 220.

Example 6

In Example 3, the process was simulated in the same manner as in Example 3, except that 90% of the discharge stream from the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

Example 7

In Example 4, the process was simulated in the same manner as in Example 4, except that 90% of the discharge stream from the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

Example 8

In Example 5, the process was simulated in the same manner as in Example 5 at all times, except that 90% of the discharge stream from the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

Example 9

In Example 3, the process was simulated in the same manner as in Example 3, except that 95% of the discharge stream from the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

Example 10

In Example 4, the process was simulated in the same manner as in Example 4 at all times, except that 95% of the discharge stream at the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

Example 11

In Example 5, the process was simulated in the same manner as in Example 5 at all times, except that 95% of the discharge stream from the bottom of the separator 200 was branched and heated by the heat exchanger 220 and then refluxed to the separator.

comparative example One

As shown in the process flow diagram shown in FIG. 2, styrene monomer, butadiene monomer, cyclohexane as a solvent and n-butyllithium as an initiator are supplied to the reactor 100 composed of an agitator and a jacket, and polymerization is performed to obtain a polymer solution after polymerization. obtained. At this time, the polymer concentration in the polymer solution was 20% by weight (5 tons of polymer, 20 tons of solvent). Then, the stream containing the polymer solution is supplied from the reactor 100 to a blowdown tank (not shown) to recover some solvent in the gas phase under reduced pressure using residual heat remaining in the polymer solution, and polymer from which some solvent has been removed. solution was drained. At this time, the amount of some of the solvent recovered in the gaseous phase was 2.8 tons, and the concentration of the polymer solution from which some of the solvent was removed was 22.5% by weight. Then, the stream containing the polymer solution from which some of the solvent has been removed from the blowdown tank (not shown) is transferred to the steam stripping process unit 300 to recover steam and the solvent in the gas phase through direct steam contact, and solid polymer was obtained. At this time, the amount of steam used in the steam stripping process unit 300 was 13.8 tons. Then, the solid polymer is put into a dryer (not shown) in the product manufacturing process along with circulating water (water) present for the transport of the solid polymer in the steam stripping process unit, and the residual solvent and moisture are discharged as waste gas and discarded, A final solid polymer product was obtained. At this time, the residual solvent in the solid polymer introduced into the dryer (not shown) was 0.5% by weight.

comparative example 2

As shown in the process flow diagram shown in FIG. 3, styrene monomer, butadiene monomer, cyclohexane as a solvent and n-butyllithium as an initiator are supplied to the reactor 100 composed of a stirrer and a jacket, and polymerization is performed to obtain a polymer solution after polymerization. obtained. At this time, the polymer concentration in the polymer solution was 20% by weight (5 tons of polymer, 20 tons of solvent). Then, the stream containing the polymer solution is supplied from the reactor 100 to a blowdown tank (not shown) to recover some solvent in the gas phase under reduced pressure using residual heat remaining in the polymer solution, and polymer from which some solvent has been removed. solution was drained. At this time, the amount of some of the solvent recovered in the gaseous phase was 2.8 tons, and the concentration of the polymer solution from which some of the solvent was removed was 22.5% by weight. Then, the stream containing the polymer solution from which some of the solvent has been removed from the blowdown tank (not shown) is transferred to the separator 200 connected to the discharge line of the blowdown tank (not shown) through a pump (not shown). The solvent was further volatilized to obtain a polymer solution having a high polymer concentration. At this time, in the additional volatilization of the solvent in the separator 200, a branch stream obtained by branching 80% of the lower discharge stream of the separator 200 containing a polymer solution having a high polymer concentration is heated by the heat exchanger 220. After refluxing to the separator 200, the residual stream including the remainder of the lower discharge stream of the separator 200 was supplied to the following stripping process unit 300. At this time, the amount of steam supplied to the heat exchanger 220 was 0.3 ton, the amount of additionally volatilized solvent was 2.2 ton, the concentration of the polymer solution with the increased polymer concentration was 25.0% by weight, and the heat exchanger 220 The vapor ratio of the branched stream that was heated and then refluxed to the separator 200 was 7% by weight.

The vaporization of the solvent in the branch stream heated by the heat exchanger 220 and then refluxed as a result of not adjusting the vapor rate through the pressure control valve 230 differently from the embodiments. While this occurred, fouling, which is a clogging phenomenon of the heat exchanger due to polymer accumulation, occurred, and accordingly, a problem occurred in that the operation of the solvent recovery device had to be shut down.

Experimental example

In the polymer manufacturing process of Examples 1 to 11 and Comparative Example 1, the amount of heat (A) used in the heat exchanger 220, the amount of steam (B) and the discharge temperature (C), and the steam stripping process unit 300 Concentration of polymer transported to (D) and amount of steam (E), sum of total steam used in the process (F), amount of residual solvent in solid polymer (G), and color of final solid polymer product (H) and whether or not fouling occurred in the device (I) were measured and shown in Table 1 below.

heat exchanger steam stripping steam product fouling A B C D E F G H I unit Gcal ton ℃ weight% ton ton weight% Visually - Example 1 0.17 0.3 86.9 25.0 12.0 12.3 0.5 White doesn't exist Example 2 0.46 0.9 96.3 29.9 9.4 10.3 0.5 White doesn't exist Example 3 0.67 1.3 106 35.0 7.4 8.8 0.5 White doesn't exist Example 4 0.83 1.7 115.5 39.9 6.0 7.7 0.5 bright yellow doesn't exist Example 5 0.95 1.9 125.2 45.0 4.9 6.8 0.5 bright yellow generation Example 6 0.67 1.3 93.5 35.0 7.4 8.8 0.5 White doesn't exist Example 7 0.83 1.7 98.2 39.9 6.0 7.7 0.5 White doesn't exist Example 8 0.95 1.9 103.1 45.0 4.9 6.8 0.5 White generation Example 9 0.67 1.3 88.2 35.0 7.4 8.8 0.5 White generation Example 10 0.83 1.7 90.8 40.0 6.0 7.7 0.5 White generation Example 11 0.95 1.9 93.5 45.0 4.9 6.8 0.5 White generation Comparative Example 1 0.00 0.0 - 22.5 13.8 13.8 0.5 White doesn't exist

Referring to Table 1, as the concentration (wt%) of the polymer in the polymer solution transferred to the steam stripping process unit 300 increases, the amount of steam used in the steam stripping process unit 300 is reduced, and used in the process It can be confirmed that the total amount of steam being used is reduced.

In addition, when the concentration of the polymer introduced into the steam stripping process unit 300 exceeds 40% by weight (Examples 5 and 8), the heat exchanger 220 and the pump 210 circulated to the heat exchanger 220 It can be confirmed that fouling has occurred in the pipe. As such, when fouling occurs, the heat exchange efficiency is lowered, so that the operation of the process is stopped, thereby reducing economic feasibility.

In addition, when the temperature at which the polymer is heated and discharged from the heat exchanger 220 exceeds 110° C. (Examples 4 and 5), it can be confirmed that the color of the finally obtained solid polymer has changed.

In addition, as in Examples 9 to 11, when 95% of the discharge stream from the bottom of the separator 200 is branched and heated by the heat exchanger 220 and then refluxed to the separator 200, the excess stream is transferred to the separator 200 It was confirmed that fouling in the pipe may occur due to flow rate instability and differential pressure increase by inflow and discharge.

100: reactor 200: separator
110, 210: pump 220: heating device
230: pressure control valve 300: steam stripping process

Claims (12)

Obtaining a polymer solution by supplying a polymerization reaction product containing one or more monomers and a solvent to a reactor (S10);
supplying the stream containing the polymer solution to a separator to separate an upper discharge stream containing a solvent in a vapor phase and a lower discharge stream containing a polymer solution (S20); and
A branched stream obtained by branching a portion of the lower discharge stream of the separator is heated with a heating device and then refluxed to the separator, and a remaining stream including the remainder of the lower discharge stream of the separator is supplied to a steam stripping process unit (S30) including,
The vapor ratio of the branched stream that is heated by the heating device and then returned to the separator is controlled by a pressure control valve,
In the step (S30), the mass flow rate of the branched stream branched from the lower discharge stream of the separator and returned to the separator to the total flow rate of the lower discharge stream of the separator is 80 to 90%,
In the step (S30), the polymer concentration of the polymer solution in the residual stream of the separator supplied to the steam stripping process unit is 20 to 40% by weight,
In the step (S30), the temperature of the stream heated from the branch stream of the separator and refluxed to the separator is 80 to 110 ° C. According to claim 1,
The method for recovering a solvent in which the one or more monomers include styrene and butadiene. According to claim 1,
After the step (S10) and before the step (S20), the step of supplying the polymer solution to a blow down tank and discharging the solvent into a gas phase using residual heat of the polymerization reaction recovery method. According to claim 1,
After the step (S30), the solvent recovery method further comprising a step (S40) of obtaining a solid polymer by volatilizing the solvent from the remaining stream of the separator supplied to the steam stripping process unit. According to claim 1,
In the step (S30), the solvent recovery method in which the branch stream of the separator is heated by passing through a heat exchanger. delete delete According to claim 1,
In the step (S30), the viscosity of the polymer solution in the residual stream of the separator supplied to the steam stripping process unit is 1,000 to 10,000 cp. According to claim 1,
The solvent recovery method in which the vapor ratio of the branch stream after being heated by the heating device until passing through the pressure control valve is adjusted to 0 to 2% by weight. delete a reactor to which a polymerization reactant including one or more monomers and a solvent is supplied and a stream containing a polymer solution obtained through polymerization of the polymerization reactant is discharged;
a separator receiving the discharge stream of the reactor and discharging an upper discharge stream containing a solvent in a vapor phase and a lower discharge stream containing a polymer solution;
a heating device which heats a branched stream obtained by branching a part of the lower discharge stream of the separator and refluxes it to the separator;
a pressure control valve for controlling a vapor ratio of the branched stream that is heated by the heating device and then returned to the separator; and
A solvent recovery device comprising a steam stripping process unit for receiving the remaining stream including the remainder of the lower discharge stream of the separator and volatilizing the solvent in the polymer solution. According to claim 11,
The solvent recovery apparatus further comprising a blowdown tank receiving the exhaust stream of the reactor, discharging the solvent in a gas phase using residual heat of the polymerization reaction, and discharging a lower exhaust stream containing a polymer solution to the separator.

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