WO2015043720A1

WO2015043720A1 - Method for the polymerization of ethylenically unsaturated monomers and reactor suitable therefor

Info

Publication number: WO2015043720A1
Application number: PCT/EP2014/002471
Authority: WO
Inventors: Michael Benje; Peter Kammerhofer; Andreas Doll; Detlef KEIL; Peter Langen; Peter Wallner
Original assignee: Thyssenkrupp Industrial Solutions Ag; Vinnolit Gmbh & Co. Kg
Priority date: 2013-09-30
Filing date: 2014-09-12
Publication date: 2015-04-02
Also published as: DE102013016178A1

Abstract

The invention relates to a method for the polymerization of ethylenically unsaturated monomers in a polymerization reactor, the cooling system thereof being divided into sections, only the least number of required sections being cooled with cold water, cooling water flowing through the remaining sections. The invention also relates to a polymerization reactor for device for carrying out said method. Said invention enables the operational costs and investment costs for cooling the cold water in geographical areas where the temperature of the cooling water is high, to be reduced.

Description

description

The invention relates to a process for the polymerization of ethylenically unsaturated monomers, such as monomeric vinyl halides, in a polymerization reactor.

Furthermore, the invention relates to a polymerization reactor for carrying out the method according to the invention. Polymerization of ethylenically unsaturated monomers is usually one

Exothermic reaction in which large amounts of heat are usually released (eg 1550 kJ / kg in the polymerization of vinyl chloride). For economic reasons, large pressure vessels of up to 300 m ³ are often used for discontinuous polymerization, so that considerable amounts of heat must be dissipated. Therefore, numerous processes and modifications of reaction vessels (reactors) for improved dissipation of the heat of reaction have already been developed for a batchwise polymerization of ethylenically unsaturated monomers, such as monomeric vinyl halides (such as vinyl chloride). In particular, for the polymerization of vinyl chloride is added that the discharged from the reactor heat flow during the reaction runs through a maximum.

In the polymerization technique, e.g. from DE 197 23 977 A1 and "Technical Progress for PVC", Y. Saeki and T. Emura, Prog. Polym., Be 27 (2002) 2055-2131 known to dissipate the heat of reaction on reactor walls (jacket cooler, wherein a discharge of In particular in the case of larger reactors, the baffles which are in any case required as components of the stirring system are additionally used for cooling

CONFIRMATION COPY It should be noted, however, that with increasing reactor size and almost constant reactor height to diameter ratio, the ratio of cooling area to volume decreases steadily. Since the heat flow from the interior of the reactor to the cooling medium has to pass through the pressure-bearing wall, the heat transfer coefficient is low.

In principle, three starting points are suitable for improving the heat release from a reactor:

- the increase of the heat transfer coefficient,

- the enlargement of the heat exchange surface, and

- the increase of the driving temperature difference between

Reactor contents and cooling medium.

Instead of a jacket cooler on the reactor outer wall can also be a reactor with

Internal coolers are used, see, e.g. EP 0 012 410 A1, US-A-4,552,724 and Shinkai T., Shinko Pfaundler Tech. Rep. 1988, 32 (3) 21-6. It can by

Reducing the wall thickness between the cooling medium and the reactor interior

Heat transfer can be significantly improved. EP 0 012 410 A1 describes, in particular, an attachment of cooling medium-carrying semi-coils to the inner wall of the reactor, which, in addition to improving the heat transfer coefficient, further improves the heat dissipation as a result of the increase in the heat exchange surface due to the curvature of the cooling coils.

The heat exchange surface can be significantly improved by additional external coolers. Here, first of all, the heat removal by evaporative cooling using a conventional reflux condenser should be mentioned. By adding a reflux condenser to a polymerization reactor, its performance can be increased by about 50%. But the large amounts of monomer, which must be evaporated and re-liquefied in the reflux condenser must be stirred back into the reaction mixture, engage in the difficult grain formation process. Furthermore, inert gas and foam problems must be solved. A high foaming of the reaction mixture in the reflux condenser must be avoided at all costs, since its condensation surfaces are then occupied and the heat removal and thus the proper completion of the polymerization batch are no longer guaranteed.

Another method for creating additional cooling surfaces is the circulation of the reaction mixture described in EP 0 526 741 A2 by means of an external heat exchanger. This process has two significant problems. For one thing that leads

Circulating a dispersion easily tends to deposit or block the system, and on the other hand, a dispersion pump has difficulty

controlling influence on the particle size distribution. According to Saeki et al. in prog. polym. Be. 27 (2002) 2055-2131 can not be said with certainty to date whether this method is already being used commercially.

An increase in the driving temperature difference by choosing a higher one

Polymerization temperature is only conditionally possible with the radical mechanism in which ethylenically unsaturated monomers are generally polymerized, since this temperature controls the average chain length of the polymer. The goal of the reaction is, however, to produce a polymer with a predetermined average chain length. Thus, the driving temperature difference can only be increased by using a cooling medium with the lowest possible temperature. Normal cooling water, as provided by wet-lava towers, is usually the cooling medium of choice because of its low deployment cost. The theoretically achievable lowest cooling water temperature of the wet cooling tower is determined by the wet bulb temperature, which in turn depends on the temperature and the relative humidity at a location. In practice, on the

Wet bulb temperature still the so-called cooling limit distance are added. In temperate countries, the climate allows cooling water temperatures of 20 ° C or even lower cooling water temperatures in winter. This allows good space-time yields (mass product per cubic meter of reaction volume and operating year) of polymerization reactors. However, petrochemical industry complexes, in which vinyl polymers are produced, are often produced in countries in tropical or subtropical latitudes near oil or natural gas production facilities. Due to the high temperatures prevailing there, often in conjunction with high humidity, only cooling water temperatures in the range of about 25-38 ° C are then possible, so that the reactor productivity drops significantly. To a desired

To produce an annual production of polymer, a plant operator had previously set up more reactors and invest more money accordingly or special measures had to be taken to lower the temperature of the cooling water. Through the use of cold water, a performance increase can be achieved as by a reflux condenser. However, the cold water must be generated with high power consumption by chillers (eg compression chillers). During wet cooling towers electricity only for the operation of the cooling water pumps, to

Cooling water circulation require compression refrigerators additionally large amounts of electricity to generate the low temperatures. The machines themselves incur additional investment costs.

The disadvantage of the high power consumption could be through the use of

Absorption chillers are greatly mitigated. In these, the necessary pressure increase of the refrigerant is not carried out by an electrically operated compressor as in compression refrigerators, but by external heat supply (e.g.

Urbanek, T .; Cold storage: fundamentals, technology and application; Oldenburg Verlag 2012). In sum, this additional heat requirement leads to a much lower efficiency compared to compression refrigerators. For this reason, absorption refrigeration systems are only particularly well if large amounts of heat otherwise unusable heat are available free of charge. In comparison to compression refrigeration machines absorption refrigerators have the far Higher plant complexity, a higher space requirement and a higher

Total weight. This is reflected in higher investment costs per kW of installed cooling capacity. In the case of cooling with cold water as coolant, the entire amount of heat to be removed from the reactor is removed via the chiller, even in phases of the polymerization, where the reaction heat output could or could be dissipated again by cooling water, i. in polymerizations of vinyl chloride also before and after passing through the maximum of heat generation. In many locations there is also a marked seasonal course of the

Cooling water temperatures, which would allow it, at least a few months

Cold water and the power-intensive operation of the chillers to do without. It is desirable to be able to divide the heat flexibly between the two cooling media cooling and cold water. Then a smaller refrigeration system would be needed, which would reduce the operating costs and the investment costs.

For such cooling, in which two cooling media can be optimally used on a reactor, there has hitherto been no solution which the mentioned

Fully satisfied claims. If, after the start of a polymerization, it is first cooled with cooling water until the cooling capacity is no longer sufficient, then the

Coolant supply to the reactor is completely switched to cold water until the

Heat development is sufficient enough for a return switch to cooling water, charged in the cooling phase with cold water still the entire heat output of the reactor, the chillers, so that their size (installed cooling capacity) compared to the operation can not be reduced only with cold water. If the cold water is used in such a way that it cools the cooling water, which in turn cools the reactor, via heat exchangers, the driving temperature difference necessary for the operation of the heat exchanger requires a lower chilled water temperature, which increases the operating costs of the refrigerating machines, because the efficiency with decreasing cold water temperature also decreases. Is the cooling water with cold water to the respective required

Temperature mixed, runs at times warm cooling water in the return to Chiller, where it must be cooled with additional energy input to the cold water flow temperature down.

An object of the present invention is to provide a process for the polymerization of ethylenically unsaturated monomers in a polymerization reactor, which is particularly economical by using cold water, but not exclusively in countries with subtropical or tropical climate by high space-time yields and at the same time with Installation and operation of refrigeration systems associated investment and operating costs minimized. In addition, it is an object of the invention to provide an apparatus for carrying out the polymerization process according to the invention. The product properties must not be significantly impaired.

Surprisingly, it has now been found that the object becomes solvable when the cooling device is subdivided at the reactor into a sufficient number of sections connected in parallel and equipped with individual coolant supply lines, which can then be selectively and reversibly operated with cooling or cold water. The solution found is represented by the independent and dependent claims as well as the description in connection with the figures. The invention overcomes the aforementioned disadvantages of the prior art.

The invention thus relates to a polymerization process in which ethylenically unsaturated monomers, in particular vinyl compounds, and preferably monomeric vinyl halides are polymerized in a reactor, wherein the heat dissipation via cooling devices on the reactor, which are divided into parallel cooling zones, that depending on the current Reaction heat output is a maximum possible cooling zone number with cooling water and only the remaining number of cooling zones with cold water is applied. The temperature-controlled switching of a zone can be done via valves.

In addition, the subject matter of the invention is a device which allows the method according to the invention to be carried out. The invention therefore relates to a process for the polymerization of one or more ethylenically unsaturated monomers in a reactor (1), which comprises the following steps:

i) provision of cooling water (3) which is optionally circulated through one or more cooling towers or other recooling devices, ii) production of cold water (4) by cooling water in a cold water plant below the cooling water flow temperature,

(iii) provision of cold water (4), where appropriate through the

Cold water system is led in a circle,

iv) introduction of the ethylenically unsaturated monomer (s) together with the other constituents of the formulation in a reactor (1) with at least two parallel-connected cooling devices of the reactor wall ("cooling zones") which can be selectively and reversibly charged with cooling water or with cold water, and

v) simultaneous removal of the resulting heat of reaction during a

ongoing polymerization of cooling water and cold water, wherein depending on the current reaction heat power one or more cooling devices of the reactor wall with cooling water and the other cooling devices of the

Reactor wall to be operated with cold water.

The polymerization of ethylenically unsaturated monomers, such as vinyl halides and in particular of vinyl chloride, is known per se. Surprisingly, it has now been found, however, that no losses in product quality are to be tolerated by the process according to the invention of the simultaneous cooling of the polymerization reactor with both cold and cold water compared with the conventional prior art.

With the method according to the invention, the cold water requirement and thus the power requirement of a polymerization of monomeric vinyl halides in a

Polymerization reactor with constant product quality compared to a

Exclusive cold water cooling significantly reduced and productivity in comparison significantly increased to a conventional jacket cooling with cooling water. In particular, it is surprising that in the process according to the invention, the temperatures of the inner wall of the reactor which are locally different due to the two different temperature-controlled cooling media have no appreciable influence on the product quality.

The inventive method is basically suitable for the radical polymerization of all ethylenically unsaturated monomers. Examples of ethylenically unsaturated monomers are halogenated olefins, such as vinyl halides or vinylidene halides, vinyl esters, such as vinyl acetate ("VA"), esters and / or amides of ethylenically unsaturated carboxylic acids, such as acrylates or methacrylates, dienes, such as 1,3-butadiene or vinylaromatics like styrene.

Vinyl chloride ("VC") is preferably used as monomeric vinyl halide, it being possible for the polymer produced to consist, for example, of 50% to 100% of vinyl chloride.

More preferably, identical or different monomer units according to the invention can be polymerized to give a homo- or copolymers. Advantageously, polymer products produced by the process according to the invention do not appreciably alter the product properties.

The reaction can be carried out according to the invention in solution or in dispersion, i. Starting materials and / or products of the reaction can be dissolved independently of one another in a solvent or be finely distributed as solids or liquids in a dispersion medium. In the method according to the invention, preference is given to

Polymerization carried out in dispersion with water as a dispersion medium.

The process of the invention may be carried out under a pressure higher than atmospheric pressure, preferably under a pressure of 0.3 to 2 MPa. Preferably, the polymerization is carried out batchwise. The invention also provides an apparatus for carrying out the method described above. This is a device comprising the following elements:

A) reactor (1) for the polymerization of ethylenically unsaturated monomers equipped with at least two parallel-connected cooling devices of the reactor wall ("cooling zones"),

B) apparatus for providing cooling water (3) connected to the entrances of each cooling device of the reactor wall,

C) cold water system for generating cold water (4), which is connected to the inputs of each cooling device of the reactor wall, and

D) switching devices for switching the supply of a cooling device of the reactor wall or a group of cooling devices of the reactor wall from cooling water (3) to cold water (4) or from cold water (4) to cooling water (3).

The apparatus provided for carrying out the method according to the invention is a reaction vessel preferably equipped with one or more stirring devices, the cooling devices of which are divided into zones connected in parallel, the reactor wall being in at least two, preferably two to fifty, in particular divided into two to thirty and more preferably two to twenty parallel zones, each of these zones can be supplied with cold water or with cooling water and switchable with at least one cooling water source and at least one

Cold water source is connected. Preferably, each of these zones is switchable part of a cooling water or a cold water circuit.

The switching is preferably carried out simultaneously both in the flow and in the return of a zone. The temperature-controlled switching of a cooling zone can take place via 3-way valves or via individual valves. Preferably, two interlocking arrangements with structurally different control accuracy are used. Thus, in the case of a heat release in the reactor, which exceeds the amount of heat which can be dissipated via the cooling water, one or more is preferred Cooling zones switched from cooling water to cold water. In particular, first a cooling zone is switched from cooling water to cold water. Subsequently, the

Cold water mass flow adapted to the current heat release, for example by a series-connected TC-FC control. Is the maximum

Cooling water flow reached and the heat release continues to increase, can be switched over the temperature circuit (TS) another cooling coil of cooling water to cold water.

Advantageously, the reaction described in EP 0 012 410 A1

Construction used as a polymerization reactor, since its internal

Cooling coil is already divided for the sake of pressure loss in several sections and also offers the benefits described increased heat transfer coefficient and increased cooling surface. A cooling zone can consist of a

Single section of the internal cooling coil exist.

A reactor which is preferably used according to the invention thus consists of a container provided with baffles, in which there is at least one agitator, preferably a multi-blade agitator, and on the wall thereof,

preferably on the inner wall, heat exchange structures are arranged.

In a further embodiment of the invention, a plurality of cooling zones may be grouped together to form the number of valves associated with the

Implementation of the switching is required to reduce. The present invention overcomes the disadvantages of the prior art, in particular by maximizing the heat dissipation by the cooling water, which is

Operating costs of a polymerization of ethylenically unsaturated monomers with constant product quality significantly reduced. Description of the figure In the following the invention will be explained with reference to a figure showing preferred embodiments of the device according to the invention.

The figure shows a preferred embodiment of an inventive

Polymerization reactor, which can be used for carrying out the method according to the invention. Illustrated by way of example is a reactor (1) which is equipped with an internal cooler (2) and is supplied with cooling water (3) and, if required, with cold water (4). The inner cooler (2) - here in the form of an internal half-pipe cooling coil - is divided into sections, which form the cooling zones and have their own connections for coolant supply and return. For illustrative reasons, only three cooling zones are shown. At the start of the reaction, all three-way valves are arranged so that all cooling zones are flowed through with cooling water, and a control cascade consisting of the internal temperature controller (6) and the cooling water flow regulator (7) keeps the reactor temperature at the setpoint. If the heat release in the reactor increases to such an extent that even with maximum cooling water flow (maximum open valves of the controller (7)), the heat dissipation is insufficient, a cooling zone by switching the three-way valves in the forward and in the return controlled by the temperature switch TS (5) Chilled water mode switched. The control valve in the cooling water supply line remains fully open. The controller for the inside temperature of the reactor now regulates the cold water flow rate via controller (8) so that the internal temperature of the reactor remains at its setpoint. If the heat release in the reactor finally increases to such an extent that the control valve of the cold water regulator (8) is fully open, the

Temperature switch (5) the next cooling zone from cooling to chilled water operation. As the heat demand continues to increase, further cooling zones (not shown) are switched to cold water by means of their three-way valves. Is the maximum the

Heat development exceeded and decreases the required cooling capacity recognizable by the decreasing cold water flow rate (3) again, the last switched to cold water cooling zone is switched back to the cooling water supply. At the end of the polymerization then again all cooling zones with cooling water

flows through. A model calculation shows that the multi-zone cooling according to the invention over the prior art as cooling with cold water or cooling water for a

Cooling water year course of a plant operated in tropical or subtropical climates is clearly beneficial. Both operating and investment costs are a minimum in multi-zone cooling.

The following examples illustrate the invention without limiting it.

Example 1: Preparation of S-PVC having a K value of about 67

Polymerization of vinyl chloride was carried out at a temperature of 57.3 ° C in a 1 m ³ experimental reactor with internal cooling coil and a cooling surface of about 6.4 m ² . The reactor had a total of 5 cooling zones, each with 1.28 m ² cooling surface. In the comparative experiments, all five cooling zones were integrated in parallel into a cooling circuit, the contents of which were circulated by a coolant pump. the

Circulation was fed fresh cooling water from the outside. At the same time an equal amount flowed out of the cycle and was returned to the cooling tower. The supply of fresh cooling water was controlled via a control cascade so that the internal reactor temperature was kept constant.

In the experimental examples according to the present invention, four of the five cooling zones were flowed through by means of regulated feed of medium pressure steam to a constant temperature adjusted water. As a result, the cooling zones acted upon by cooling water were simulated according to the present invention. This

The procedure was necessary because in the pilot reactor, the ratio of cooling area to volume was very large and otherwise there would be no significant differences between the coolant temperatures in the different cooling zones. The fifth cooling zone represented a zone subjected to cold water according to the present invention. Only this cooling zone was used in the same way as in the reference experiments for keeping constant the internal reactor temperature.

For K value 67, 450 kg of VCM (vinyl chloride monomer) were polymerized. In the approaches commercially available suspending aids and a Peroxydicarbonat as Initiator used. Here, the time sequence of the addition of the individual substances had no effect on the process. The reaction was stopped at a conversion of about 85% after 3 h. In comparison, the four parallel cooling zones were operated with water tempered to 55 ° C. The internal reactor temperature was kept constant at 51.5 ° C by controlling the water temperature in the fifth cooling zone. As a minimum, the flow temperature reached a value of 23 ° C.

For the reference experiment, all 5 cooling zones were exposed in parallel to cooling water to the same reactor under the same setting and the same conditions. As a minimum, the cooling water flow temperature reached a value of 48.5 ° C.

The powder properties of the product prepared by the process of the invention are summarized in Table 1 together with those of the product prepared by the reference method. It was found that the powder properties of the products of both methods showed no significant deviations.

Table 1: Powder properties S-PVC K value 67

Size Unit Reference with unit reference with inferior flow temperature according to different cooling water cooling water temperatures

K value - 66.1 66.4

Bulk weight g / i 564 560

Porosity% 21, 8 21, 6

average grain size 180.8 179.4

diameter

Sieve residue% 100 100

> 63 μηι

Sieve residue% 13.2 13.2

> 250 in

Sieve residue% 0.3 0.2

> 355 in Measure of the - 2.22 2.26

Width of

grain distribution

Example 2: Preparation of S-PVC having a K value of about 70

Polymerization of vinyl chloride was carried out at a temperature of 53.5 ° C using the reactor of Example 1. 430 kg of VC were used, which were polymerized in about 4 hours to a conversion of about 83%.

The suspending aid additions and initiator concentration were matched to the experiment.

In the experiment, the four parallel cooling zones were operated with water tempered to 50 ° C. The internal reactor temperature was kept constant at 53.5 ° C by controlling the water temperature in the fifth cooling zone. As a minimum, the flow temperature here reached a value of 32.5 ° C.

For the reference experiment, all 5 cooling zones were exposed in parallel to cooling water to the same reactor under the same setting and the same conditions. As a minimum, the cooling water flow temperature reached a value of 46.5 ° C. It was found that the powder properties were not significantly hindered (Table 2).

Table 2: Powder properties S-PVC K value 70

Size unit reference with reference with

more uniform according to the invention

Flow temperature of the different

Cooling water cooling water temperatures

K value - 70.1 69.9 Bulk weight g / i 468 474

Porosity% 30.3 30.9

average grain size 135 130,2

diameter

Sieve residue% 99.6 99.5

> 63 in

Sieve residue% 65.2 66.4

> 125mm

Sieve residue% 0.4 0.3

> 250mm

Measure for the 2,33 2,3

Width of

grain distribution

Example 3: Preparation of a random copolymer of vinyl chloride and vinyl acetate having a K value of about 57

Co-polymerization of vinyl chloride vinyl acetate was carried out using the reactor of Example 1. 380 kg VC plus 70 kg were used

Vinyl acetate, which were polymerized in about 3 hours. The suspending aid additions and initiator concentration were matched to the experiment.

In the experiment, the four parallel cooling zones were operated with water tempered to 60 ° C. The internal reactor temperature was kept constant at 62.5 ° C by controlling the water temperature in the fifth cooling zone. As a minimum, the flow temperature reached a value of 27 ° C.

For the reference experiment, all 5 cooling zones were exposed in parallel to cooling water to the same reactor under the same setting and the same conditions. As a minimum, the cooling water flow temperature reached a value of 53.4 ° C. It was found that the powder properties were not significantly changed (Table 3)

Table 3: Powder properties VC VA copolymer K value 57

Size unit reference with reference with

more uniform according to the invention

Flow temperature of the different

Cooling water cooling water temperatures

K value - 57.5 57.3

Bulk weight g / i 663 654

Vinyl acetate% 11, 2 10.7

salary

Sieve residue% 85 88

> 63 pm

Sieve residue% 0.5 0.3

> 250mm

Claims

Claims 213ku06.de

A process for the polymerization of one or more ethylenically unsaturated monomers in a reactor (1), comprising the steps of:

(iii) provision of cold water (4), where appropriate through the

Cold water system is led in a circle,

iv) presentation of the ethylenically unsaturated monomer (s) together with the other constituents of the formulation in a reactor (1) with at least two parallel-connected cooling devices of the reactor wall, which can be selectively and reversibly supplied with cooling water or with cold water, and

v) simultaneous removal of the resulting heat of reaction during a

Reactor wall to be operated with cold water.

2. The method according to claim 1, characterized in that the cooling devices of the reactor wall are arranged in parallel zones in which the heat dissipation of cooling water and cold water takes place, each zone is optionally acted upon with cooling or cold water.

3. The method according to claim 2, characterized in that depending on the current

Heat development in the reactor (1) Switching zones from cooling water to cold water operation or back.

4. The method of claim 2, wherein always only so many zones with cold water

be operated as it for the removal of just in the reactor (1) accumulating

Amount of heat is at least necessary.

5. The method according to claim 1, characterized in that the cooling water is circulated through one or more cooling towers or other recooling devices.

6. The method according to claim 1, characterized in that the cold water system is an absorption chiller or in particular a compression chiller.

7. The method according to any one of claims 1 to 6, characterized in that the one or more ethylenically unsaturated monomers are vinyl compounds, in particular a vinyl halide is used as the exclusive monomeric vinyl compound.

8. The method according to claim 7, characterized in that as the vinyl halide

Vinyl chloride is used.

9. The method according to any one of the preceding claims, characterized in that the polymerization is carried out in a dispersion or a solvent, in particular in aqueous suspension.

10. The method according to any one of the preceding claims, characterized in that the polymerization is carried out at a pressure of 0.3 to 2 MPa.

11. The method according to any one of the preceding claims, characterized in that the polymerization is carried out batchwise.

12. An apparatus for carrying out the method according to claim 1 comprising the following elements:

A) reactor (1) for the polymerization of ethylenically unsaturated monomers equipped with at least two parallel-connected cooling devices of the reactor wall,

B) apparatus for providing cooling water (3) connected to the entrances of each cooling device of the reactor wall, C) cold water system for generating cold water (4), which is connected to the inputs of each cooling device of the reactor wall, and

D) switching devices for switching the supply of a cooling device of the reactor wall or a group of cooling devices of the reactor wall from cooling water (3) to cold water (4) or from cold water (4) to cooling water

(3).

13. The apparatus according to claim 12, characterized in that the reactor (1) is equipped with one or more stirring devices reaction vessel, the cooling devices of the reactor wall in at least two, preferably two to fifty, in particular two to thirty and particularly preferably two to twenty parallel divided zones are divided, and wherein each of these zones can be supplied with cold water or with cooling water and is switchable connected to at least one cooling water source and at least one cold water source.

14. The device according to claim 13, characterized in that each of the zones

switchable forms the part of a cooling water or a cold water circuit.

15. The apparatus according to claim 12, characterized in that the switching devices constitute 3-way valves or individual valves.

16. The apparatus according to claim 12, characterized in that the reactor (1) comprises a container provided with baffles in which there is at least one agitator and arranged on the wall of heat exchanger constructions.

17. Device according to one of claims 12 to 16, characterized in that the reactor (1) has internal cooling coils.

18. Device according to one of claims 14 to 17, characterized in that each zone can be switched separately into the cooling or the cold water circuit

can be included.

19. The device according to any one of claims 13 to 18, characterized in that some or all zones are portions of the reactor (1) external or internal cooling coil or on the reactor (1) external or internal cooling jacket.