Method and system for producing a polymer

Abstract

The invention relates to a method for producing a polymer from a first component and a second component by means of a reactor (50), wherein reaction heat in the reactor (50) is discharged via an evaporative cooler (40), wherein gaseous exhaust vapour in the reactor (50) is supplied to the evaporative cooler (40), and condensed exhaust vapour is guided from the evaporative cooler (40) back into the reactor (50). In this way, the first component and/or second component are supplied at least partially via the evaporative cooler (40) and moved from the evaporative cooler (40) into the reactor (50). The invention also relates to a system for producing a polymer, comprising a reactor (50) and an evaporative cooler (40) for discharging reaction heat in the reactor (50). In addition, the evaporative cooler (40) has at least one filling opening (46) for filling in the first and/or second component.

Claims

1. A process for producing a (co)polymer from at least one first component and a second component by a reactor, where heat of reaction arising in the reactor is removed by an evaporative cooler by feeding gaseous vapor formed in the reactor to the evaporative cooler and recirculating condensed vapor from the evaporative cooler to the reactor, wherein the first component and the second component are at least partly introduced via the evaporative cooler and go from the evaporative cooler into the reactor, wherein the first component and the second component are at least partly mixed with a solvent, with the solvent being taken from a condensation unit arranged downstream of the reactor, the gaseous vapor ascending against the force of gravity in vertical tubes of the evaporative cooler and condensing in the evaporative cooler, and with the condensed vapor subsequently flowing together with the first component and the second component under the force of gravity back into the reactor.

2. The process of claim 1, wherein the first component contains styrene and wherein the second component contains acrylonitrile.

3. The process of claim 1, wherein the second component contains acrylonitrile and wherein the first component contains alpha-methylstyrene.

4. The process of claim 1, wherein the first component contains styrene and wherein the second component contains methyl methacrylate.

5. The process of claim 1, wherein the first component and/or the second component are introduced at least partly from above through a cap of the evaporative cooler.

6. The process of claim 1, wherein the first component and/or the second component are at least partly introduced from above into a plurality of vertical tubes of the evaporative cooler.

7. The process of claim 1, wherein the first component and/or the second component are introduced at least partly in liquid form into the evaporative cooler.

8. The process of claim 7, wherein the solvent is taken via a collection vessel from the condensation unit arranged downstream of the reactor.

9. The process of claim 1, wherein the first component and/or the second component are at least partly introduced directly into the reactor.

10. A system for producing a polymer from at least one first component and a second component, comprising: a reactor, and an evaporative cooler for removing heat of reaction arising in the reactor, wherein the evaporative cooler has at least one feed opening for introducing the first component and/or the second component, wherein a return conduit for feeding a solvent from a condensation unit arranged downstream of the reactor into the evaporative cooler is provided, wherein the reactor and the evaporative cooler are arranged in such a way that vapor formed in the reactor ascends against the force of gravity into the evaporative cooler and that vapor condensed in the evaporative cooler flows together with the first component and/or the second component under the force of gravity into the reactor.

11. The system of claim 10, wherein the at least one feed opening is arranged in a cap of the evaporative cooler.

12. The system of claim 11, wherein nozzles are arranged in the cap in such a way that the first component and/or second component introduced through the at least one feed opening are distributed from above into vertical tubes of the evaporative cooler.

13. The system of claim 10, wherein the return conduit is connected to a collection vessel and wherein the condensation unit is connected to the collection vessel.

Description

(1) Embodiments of the invention are explained in more detail with the aid of the following drawing, the following description and the claims.

(2) FIG. 1 shows a schematic sectional view of a system for producing a polymer such as SAN.

(3) A schematic sectional view of a system 10 for producing a polymer from at least one first component and a second component is depicted in FIG. 1. The system 10 serves, in particular but not exclusively, for producing styrene-acrylonitrile copolymer (SAN), alpha-methylstyrene-acrylonitrile copolymer (AMSAN) and styrene-methyl methacrylate copolymer (SMMA).

(4) The system 10 comprises a reactor 50. In the reactor 50, a polymerization of monomers fed in takes place. A stirrer 52 is arranged within the reactor 50. The stirrer 52 can be driven rotationally by means of an electric motor which is not shown here. Other types of reactors 50 in which a polymerization of monomers fed in can take place can also be used.

(5) A first feed conduit 31 is connected to the reactor 50. The first feed conduit 31 serves for the introduction of components directly into the reactor 50. The components introduced contain, in particular, monomers. A first return conduit 36 is also connected to the reactor 50. The first return conduit 36 serves for the introduction of a solvent and also of unreacted monomers separated off during degassing. The solvent originates from a condensation unit 71, which will be discussed at a later juncture.

(6) Furthermore, an outlet conduit 34 is connected to the reactor 50. Polymer composition formed in the reactor 50 can be drained from the reactor by means of the outlet conduit 34. A degassing unit 70 is arranged upstream of the reactor 50 and connected to the outlet conduit 34. Polymer composition drained from the reactor 50 via the outlet conduit 34 thus goes into the degassing unit 70 arranged downstream.

(7) The degassing unit 70 serves, in particular, for removing volatile constituents from the polymer composition, in particular solvent and unreacted monomers. An offtake conduit 38 is connected to the degassing unit 70. The polymer produced, which is now at least largely free of unreacted monomers and solvent, can be taken from the system 10 via the offtake conduit 38.

(8) The degassing unit 70 is also connected to a condensation unit 71. Solvent and unreacted monomers which have been removed from the polymer composition in the degassing unit 70 are fed into the condensation unit 71. The solvent and the unreacted monomers condense in the condensation unit 71.

(9) The condensation unit 71 is connected to a collection vessel 80. The condensed solvent and the condensed unreacted monomers from the condensation unit 71 are fed into the collection vessel 80, A feed conduit 33 is also connected to the collection vessel 80 and serves for introducing or introducing further amounts of solvent.

(10) The first return conduit 36 which is connected to the reactor 50 and serves for introduction of the solvent and the unreacted monomers into the reactor 50 is also connected to the collection vessel 80. The solvent present in the collection vessel 80 and also the unreacted monomers can thus be recirculated in their entirety or partly via the first return conduit 36 into the reactor 50.

(11) The system 10 further comprises an evaporative cooler 40. The evaporative cooler 40 serves for removing heat of reaction arising in the polymerization in the reactor 50. The evaporative cooler 40 is in the present case configured as shell-and-tube heat exchanger and comprises a plurality of vertical tubes 44. The evaporative cooler 40 is closed, i.e. at the end facing away from the ground, by a cap 42. Furthermore, the evaporative cooler 40 comprises a coolant inlet which is not shown here and a coolant outlet which is likewise not shown here.

(12) The reactor 50 is connected to the evaporative cooler 40 in such a way that the heat of reaction arising during the polymerization in the reactor 50 can be removed by means of the evaporative cooler 40. Gaseous vapor formed in the reactor 50 is fed to the evaporative cooler 40 and condensed vapor flows from the evaporative cooler 40 back into the reactor 50.

(13) Within the evaporative cooler 40, the gaseous vapor formed in the reactor 50 ascends in the vertical tubes 44. A coolant flows around the tubes 44. The coolant is fed to the evaporative cooler 40 through the coolant inlet, flows around the vertical tubes 44 and exits again from the evaporative cooler 40 through the coolant outlet. In the process, the coolant cools the tubes 44 and also vapor from the reactor 50 which is present therein.

(14) As a result, the vapor condenses and the condensed vapor flows back into the reactor 50.

(15) One or more feed openings 46 are arranged in the cap 42 of the evaporative cooler 40. The feed openings 46 in the cap 42 of the evaporative cooler 40 serve for introducing components into the evaporative cooler 40. Furthermore, a plurality of nozzles 48 can be provided in the cap 42 of the evaporative cooler 40. The nozzles 48 are connected to the feed openings 46. Components which are introduced into the cap 42 of the evaporative cooler 40 through the feed openings 46 thus go to the nozzles 48 in the cap 42 of the evaporative cooler 40.

(16) The nozzles 48 are arranged in the cap 42 of the evaporative cooler 40 in such a way that components which are introduced through the feed openings 46 into the evaporative cooler 40 are distributed from above over all vertical tubes 44 of the evaporative cooler 40. The components introduced through the feed openings 46 into the evaporative cooler 40 thus drop under the force of gravity into the vertical tubes 44 of the evaporative cooler 40 in which the vapor from the reactor 50 condenses.

(17) A second feed conduit 32 is connected to the cap 42 of the evaporative cooler 40. The second feed conduit 32 serves for introduction of components into the evaporative cooler 40. The components fed in contain in particular monomers. The second feed conduit 32 is connected to the feed openings 46 in the cap 42 of the evaporative cooler 40. Components introduced via the second feed conduit 32 thus go via the feed openings 46 to the nozzles 48 in the cap 42 of the evaporative cooler 40 and from there into the vertical tubes 44.

(18) A second return conduit 35 opens into the second feed conduit 32. The second return conduit 35 is, like the first return conduit 36, connected to the collection vessel 80. Thus, the solvent present in the collection vessel 80 and also the unreacted monomers can be fed in their entirety or partly into the second feed conduit 32 via the second return conduit 35. The second return conduit 35 thus serves for introduction of a solvent and of the unreacted monomers into the evaporative cooler 40.

(19) In the reactor 50, a polymerization of the monomers takes place while stirring by means of the stirrer 52. Heat of reaction arises in the polymerization. The heat of reaction results in gaseous vapor ascending from the reactor 50 into the evaporative cooler 40.

(20) The gaseous vapor formed in the reactor 50 ascends in the vertical tubes 44 of the evaporative cooler 40 and is cooled there. As a result, the vapor condenses and the condensed vapor flows back into the reactor 50.

(21) The polymer composition formed in the polymerization has a solids content of about 50%-80%, preferably 60%-70%. The polymer composition is then fed via the outlet conduit 34 to the degassing unit 70. In the degassing unit 70, the volatile constituents, in particular solvent and unreacted monomers, are removed from the polymer composition. The polymer produced, which is now largely free of volatile constituents, is taken off from the system 10 via the offtake conduit 38. The solvent removed from the polymer composition and also the unreacted monomers are conveyed through the condensation unit 71 and the collection vessel 80 and recirculated in their entirety or partly via the first return conduit 36 back into the reactor 50 or recirculated in their entirety or partly via the second return conduit 35 back into the evaporative cooler 40.

(22) The components are present in liquid form. The components are introduced through the feed openings 46 in the cap 42 of the evaporative cooler 40 into the evaporative cooler 40. The components are distributed into the vertical tubes 44 of the evaporative cooler 40 via the nozzles 48 in the cap 42 of the evaporative cooler 40. Here, the components drop from above under the force of gravity into the vertical tubes 44 of the evaporative cooler 40.

(23) Due to the heat of reaction which arises as a result of the polymerization in the reactor 50, gaseous vapor also ascends against the force of gravity from the reactor 50 into the vertical tubes 44 of the evaporative cooler 40. There, the vapor is cooled and condenses. In the process, mixing of the condensed vapor with the components which are introduced from above under the force of gravity into the vertical tubes 44 of the evaporative cooler 40 takes place. The condensed vapor subsequently flows together with the components introduced into the evaporative cooler 40 back into the reactor 50 under the force of gravity. The solvent also flows from the evaporative cooler 40 into the reactor 50.

(24) The process described here for producing a polymer is based on a continuous procedure.

(25) The components are introduced continuously in their entirety or at least partly via the second feed conduit 32 into the evaporative cooler 40, or not more than partly introduced via the first feed conduit 31 into the reactor 50.

(26) The polymer produced is likewise taken off continuously via the offtake conduit 38. The solvent is circulated in the system 10. The solvent is conveyed from the condensation unit 71 via the first return conduit 36 into the reactor 50 or via the second return conduit 35 into the evaporative cooler 40.

(27) The invention is explained in more detail by the examples and claims.

(28) In a process known from the prior art for producing a polymer, the components (styrene and acrylonitrile) are introduced exclusively directly into the reactor 50. The polymer produced is taken off continuously.

(29) After a number of months up to two years, so much polymer (SAN) has been formed in the evaporative cooler that the cooling power is significantly reduced and that efficient temperature management is no longer ensured. An operating time in the range from one to two years is frequently obtained.

(30) In an experiment on production of a polymer (SAN) by means of the process of the invention in a system 10 according to the invention, the components are introduced in their entirety or partly into the evaporative cooler 40. The polymer produced is taken off continuously. In the present case, it took about five years until so much polymer had been formed in the evaporative cooler that the flow of the vapor from the reactor 50 through the evaporative cooler 40 was significantly hindered. An operating time of five years was thus obtained.

LIST OF REFERENCE NUMERALS

(31) 10 System 31 First feed conduit 32 Second feed conduit 33 Feed conduit 34 Outlet conduit 35 Second return conduit 36 First return conduit 38 Offtake conduit 40 Evaporative cooler 42 Cap 44 Tube 46 Feed opening 48 Nozzle 50 Reactor 52 Stirrer 70 Degassing unit 71 Condensation unit 80 Collection vessel