Device and method for producing partially chlorinated alkanes

Abstract

The invention relates to a device for producing partially chlorinated alkanes, said device allowing the reaction heat arising during the production of the partially chlorinated alkanes to be efficiently dissipated and reused. The invention additionally relates to a method, which can be carried out by means of the device, for producing partially chlorinated alkanes.

Description

[0001] thyssenkrupp Uhde GmbH, thyssenkrupp AG, WESTLAKE VINNOLIT GMBH &

[0002] CO. KG

[0003] P149516PC00

[0004] Apparatus and method for the production of partially chlorinated alkanes

[0005] The present invention relates to a device for the production of partially chlorinated alkanes, which allows the heat of reaction generated during the production of the partially chlorinated alkanes to be efficiently removed and used elsewhere. Furthermore, the present invention relates to a process for the production of partially chlorinated alkanes that can be carried out using the device.

[0006] In general, the use of the heat of reaction from direct chlorination by direct heat transfer via a hot process stream directly to a heat sink, or by using an intermediate heat transfer medium such as hot water, is limited by the reaction temperature of approximately 120 °C, as the number of suitable heat sinks that consume heat at a low temperature level is also limited. Therefore, there is a need for a process that recovers the heat of reaction from direct chlorination and makes it available at a versatile temperature level. This task also includes heating heat sinks within the chlor-alkali electrolysis plant, which is usually located in close proximity to a direct chlorination plant.

[0007] This problem is solved by means of the device according to claim 1. The dependent claims represent advantageous further developments.

[0008] The invention thus relates to a device for the production of partially chlorinated alkanes, comprising a loop reactor which has a first feed for an alkene to be chlorinated, a second feed for a chlorinating agent and at least one outlet arranged at the top for a gaseous product stream containing the produced partially chlorinated alkane, wherein the gaseous product stream is fed to a first heat exchanger which is designed to at least partially condense partially chlorinated alkane of the product stream and to at least partially evaporate water via a first feed for water supplied, wherein a stream containing condensed partially chlorinated alkane and a gaseous stream and a first two-phase stream containing liquid and vaporous water are discharged from the first heat exchanger.

[0009] The apparatus according to the invention provides a particularly advantageous process for the production of partially chlorinated alkanes, especially for the direct chlorination of ethylene to 1,2-dichloroethane. Due to its special reaction procedure, particularly high yields of 1,2-dichloroethane and high product purities are possible even at a high reaction temperature, typically 120°C. The special feature of the process is the dissolution of the gaseous raw materials chlorine and ethylene in the reaction medium 1,2-dichloroethane in a homogeneous liquid phase prior to the actual reaction. The reactor is a gas lift loop reactor with internal or external circulation, whereby the reaction medium is circulated naturally. The produced quantity of 1,2-dichloroethane is withdrawn as vapor at the reactor head. Ethylene is added to the main circulation stream in the reactor riser pipe, thus facilitating natural circulation.Simultaneously, the ethylene dissolves in the circulating 1,2-dichloroethane as it travels along the riser pipe. To dissolve the chlorine, a partial stream of 1,2-dichloroethane is taken from the reaction cycle and cooled to a temperature typically of 45–60 °C. At this temperature, the chlorine remains readily soluble, while side reactions such as further chlorination to 1,1,2-trichloroethane are suppressed. Due to the low final temperature of the 1,2-dichloroethane stream used for chlorine dissolution, some of its heat content is difficult to utilize for heat recovery, thus reducing the proportion of recoverable heat relative to the total heat of reaction.

[0010] To solve this problem, it is proposed to generate steam at a pressure below atmospheric pressure using the latent heat content of the vaporous 1,2-dichloroethane stream and the sensible heat content of the 1,2-dichloroethane stream used to dissolve the chlorine. This steam is then brought to a technically usable temperature level using mechanical compression units. Radial blowers are preferably used as the compressor type. The number of required compressor stages depends on the temperature level necessary for the intended technical application. A particular embodiment of the invention aims for a particularly high utilization of the heat of reaction. Here, steam is generated at at least two pressure levels below atmospheric pressure. The steam at the lower pressure level is then compressed to the pressure of the steam at the higher pressure level by means of mechanical compression.The steam streams are then combined and brought to a technically usable pressure level by means of further compression.

[0011] According to a preferred embodiment, the first two-phase stream, containing liquid and vaporous water, is fed to a first phase separation vessel designed to separate the first two-phase stream into a first liquid water phase and a first vaporous water phase. A further preferred embodiment provides that the first phase separation vessel has a top-end discharge for the first vaporous water phase, through which the first vaporous water phase is directed to an outlet.

[0012] According to a further preferred embodiment, the discharged first vaporous water phase is fed to a first compression device located upstream of the outlet. This compression device is preferably a mechanical compression device and, in particular, comprises at least one compression stage, which can, for example, be a mechanical compression stage. For example, the compression device can have one, but also two, three, or four compression stages connected in series. In a preferred embodiment of the invention, the mechanical compression stages are operated by means of a continuously generated electric current.

[0013] Another preferred embodiment provides that the first compression device has a second supply for liquid fresh water.

[0014] For example, at least part of the liquid water phase can be removed from the first phase separation vessel, in particular from the bottom, and fed to the first heat exchanger via the first water supply, with the removal preferably being carried out with a first pump.

[0015] Another preferred embodiment provides that the loop reactor has a laterally arranged discharge of a liquid circulating stream containing liquid partially chlorinated alkane, which is fed to a second heat exchanger designed to cool the liquid partially chlorinated alkane of the circulating stream and to at least partially evaporate water supplied via a second inlet for water, wherein a return stream containing cooled partially chlorinated alkane and a second two-phase stream containing liquid and vaporous water are discharged from the second heat exchanger.

[0016] According to a further preferred embodiment, the loop reactor has a rising zone and a falling zone, and the discharge of the circulating current preferably takes place from the falling zone.

[0017] Another preferred embodiment provides that the discharge of the liquid circulating flow is carried out by means of a circulating flow pump.

[0018] It is also advantageous that the second two-phase current is fed to the first phase separation tank.

[0019] It can also be provided that at least part of the recycled stream is fed into a mixing device, wherein the mixing device is designed to mix the chlorinating agent with the partially chlorinated alkane of the recycled stream, and the mixture produced in the mixing device is fed to the feed for a chlorinating agent.

[0020] Furthermore, the return flow can be split into a first partial flow and a second partial flow, wherein the first partial flow is fed to the mixing device and the second partial flow is directed into the loop reactor, preferably into the fall zone, in particular below the extraction of the liquid circulating flow.

[0021] It is further preferred if a third heat exchanger is arranged upstream of the mixing device, which is designed to cool the return flow or the partial flow and to at least partially evaporate water supplied via a second feed for water, wherein a cooled return flow or the partial flow, containing further cooled partially chlorinated alkane and a third two-phase flow, containing liquid and vaporous water, is discharged from the third heat exchanger.

[0022] It is also possible to feed the third two-phase stream into a second phase separation vessel, which is designed to separate the third two-phase stream into a second liquid water phase and a second vaporous water phase, wherein the second liquid water phase is preferably fed to the third heat exchanger via the second water inlet. It is further advantageous that the second phase separation vessel has a top-end outlet for the second vaporous water phase, through which the second vaporous water phase is led to an outlet.

[0023] Another preferred embodiment provides that the discharged second vaporous water phase is fed to a second compression device, which is arranged upstream of the outlet, preferably a mechanical compression device and comprising at least one compression stage.

[0024] According to a further preferred embodiment, the second compression device has a second supply for liquid fresh water.

[0025] It is also advantageous that the first compression device and / or second compression device are radial blowers.

[0026] Furthermore, the system may include at least one evaporator stage downstream of the outlet for the evaporation of sodium hydroxide solution, designed to be heated by the first and / or second vaporous water phase, or by the combined first and second vaporous water phase. This allows at least some of the steam generated by the process described above to be used for heating a system for evaporating aqueous sodium hydroxide solution. Typically, in such a system, sodium hydroxide solution with a sodium hydroxide concentration of approximately 32 wt% is evaporated to approximately 50 wt%. The evaporation takes place in multi-stage evaporation plants. In each stage, the evaporator with the highest sodium hydroxide concentration is heated by steam from the system boundary.The vapor stream from this evaporator stage is used to heat the evaporator stage with the next lower sodium hydroxide concentration, whereby this process includes at least two evaporator stages, but can also include three or more evaporator stages.

[0027] The invention relates to the heating of such an evaporation plant using steam generated according to the procedure described above. Previously, it had been proposed to heat a sodium hydroxide evaporation plant using hot liquid or vaporous 1,2-dichloroethane from direct chlorination. However, this approach carries the risk that leaks in heat exchangers carrying 1,2-dichloroethane could contaminate the valuable sodium hydroxide product with 1,2-dichloroethane. The invention advantageously enables the heating of the sodium hydroxide evaporation using the heat of reaction from direct chlorination without the risk of contamination.

[0028] The invention also relates to a process in which the sodium hydroxide solution from the chlor-alkali electrolysis is subjected to flash evaporation before entering the evaporation unit. This step pre-concentrates the sodium hydroxide solution by utilizing its sensible heat content. Simultaneously, the temperature reduction achieved by this step lowers the inlet temperature to the evaporation unit, resulting in higher effective temperature differences for all evaporation steps. This allows for the use of a lower pressurized vapor than would be possible without this step.

[0029] The invention further relates to a variant of the inventive method in which plate heat exchangers are used as heat exchangers for the evaporator stages.

[0030] In particular, a relaxation stage for sodium hydroxide is installed upstream of the evaporator stage, which is designed to pre-concentrate sodium hydroxide.

[0031] According to a further preferred embodiment, a distillative desalination plant for seawater is connected downstream of the outlet, which is designed to be heated by means of the first and / or second vaporous water phase or the combined first and second vaporous water phase.

[0032] The invention thus also relates to a system comprising a plant for the direct chlorination of ethylene with a plant for the distillative desalination of seawater, in which at least part of the steam produced by means of the above-described process is used to heat a plant for the distillative desalination of seawater.

[0033] In a preferred embodiment of the invention, the desalinated seawater is used to prepare brine for chlor-alkali electrolysis.

[0034] The invention also relates to a system comprising a plant for the direct chlorination of ethylene with a plant for the evaporation of sodium hydroxide and a plant for the desalination of seawater, wherein the latter plants are at least partially heated by steam generated according to the method described above.

[0035] The problem is further solved by the following procedural embodiments, compiled as sentences.

[0036] Sentence 1: A process for the production of partially chlorinated alkanes in a loop reactor comprising a first feed for an alkene to be chlorinated, a second feed for a chlorinating agent, and a top-mounted discharge for a gaseous product stream containing the produced partially chlorinated alkane, wherein the gaseous product stream is fed to a first heat exchanger, the partially chlorinated alkane of the product stream is at least partially condensed, and water supplied via a first feed for water is at least partially evaporated, wherein a stream containing condensed partially chlorinated alkane and a gaseous stream, as well as a first two-phase stream containing liquid and vaporous water, is discharged from the first heat exchanger.

[0037] Sentence 2: Method according to Sentence 1, wherein the first two-phase stream containing liquid and vaporous water is fed to a first phase separation vessel which separates the first two-phase stream into a first liquid water phase and a first vaporous water phase.

[0038] Sentence 3: Method according to the preceding sentence, wherein the first phase separation vessel has a top-side discharge for the first vaporous water phase, through which the first vaporous water phase is led to an outlet.

[0039] Sentence 4: Method according to the preceding sentence, wherein the discharged first vaporous water phase is fed to a first compression device arranged upstream of the outlet, wherein the compression device is preferably a mechanical compression device and in particular comprises at least one compression stage.

[0040] Sentence 5: Method according to the preceding sentence, wherein liquid fresh water is supplied to the first compression device via a second supply.

[0041] Sentence 6: Method according to one of sentences 0 to 0, wherein at least a part of the liquid water phase is taken from the first phase separation vessel, in particular from the bottom, and is fed to the first heat exchanger via the first water supply, wherein the withdrawal is preferably carried out with a first pump.

[0042] Sentence 7: Method according to one of the preceding sentences, wherein a liquid circulating stream containing liquid partially chlorinated alkane is discharged from the loop reactor via a laterally arranged discharge, which is fed to a second heat exchanger which cools the liquid partially chlorinated alkane of the circulating stream and at least partially evaporates water supplied via a second feed for water, wherein a return stream containing cooled partially chlorinated alkane and a second two-phase stream containing liquid and vaporous water are discharged from the second heat exchanger.

[0043] Sentence 8: Method according to the preceding sentence, wherein the loop reactor has a rising zone and a falling zone and the discharge of the circulating flow preferably takes place from the falling zone.

[0044] Sentence 9: Method according to one of the two preceding sentences, wherein the discharge of the liquid circulating flow is effected by means of a circulating flow pump. Sentence 10: Method according to one of sentences 0 to 0, wherein the second two-phase flow is fed to the first phase separation vessel.

[0045] Sentence 11: Method according to one of sentences 0 to 0, wherein at least a part of the return stream is fed into a mixing device, wherein the mixing device mixes the chlorinating agent with the partially chlorinated alkane of the return stream, and the mixture produced in the mixing device is fed to the second feed for a chlorinating agent.

[0046] Sentence 12: Method according to the preceding sentence, wherein the return flow is split into a first partial flow and a second partial flow, wherein the first partial flow is fed to the mixing device and the second partial flow is directed into the loop reactor, preferably into the fall zone, in particular below the extraction of the liquid circulating flow.

[0047] Sentence 13: Method according to one of the two preceding sentences, wherein a third heat exchanger is arranged upstream of the mixing device, which is designed to cool the return flow or the partial flow and to at least partially evaporate water supplied via a second feed for water, wherein a cooled return flow or the partial flow, containing further cooled partially chlorinated alkane and a third two-phase flow, containing liquid and vaporous water, is discharged from the third heat exchanger.

[0048] Sentence 14: Method according to the preceding sentence, wherein the third two-phase stream is fed to a second phase separation vessel, which separates the third two-phase stream into a second liquid water phase and a second vaporous water phase, wherein the second liquid water phase is preferably fed to the third heat exchanger via the second water supply.

[0049] Sentence 15: Method according to the preceding sentence, wherein the second phase separation vessel has a top-side discharge for the second vaporous water phase, through which the second vaporous water phase is led to an outlet. Sentence 16: Method according to the preceding sentence, wherein the discharged second vaporous water phase is fed to a second compression device, which is arranged upstream of the outlet, preferably a mechanical compression device and comprising at least one compression stage.

[0050] Sentence 17: Method according to the preceding sentence, wherein liquid fresh water is supplied to the second compression device via a second supply.

[0051] Sentence 18: Method according to one of sentences 0 to 0, wherein the first compression device and / or second compression device are radial blowers.

[0052] Sentence 19: Method according to one of sentences 0 to 0, wherein at least one evaporator stage for the evaporation of sodium hydroxide is connected downstream of the outlet, which is heated by means of the first and / or second vaporous water phase or the combined first and second vaporous water phase.

[0053] Sentence 20: Method according to the preceding sentence, wherein the at least one evaporator stage is operated by means of a plate heat exchanger.

[0054] Sentence 21: Method according to one of the two preceding sentences, wherein a relaxation stage for sodium hydroxide is placed upstream of the evaporator stage, which pre-concentrates the sodium hydroxide.

[0055] Sentence 22: Method according to one of sentences 0 to 0, wherein the outlet is followed by a plant for the distillative desalination of seawater, which is heated by means of the first and / or second vaporous water phase or the combined first and second vaporous water phase.

[0056] The apparatus according to the invention and the process for the production of partially chlorinated alkanes are illustrated below with reference to the direct chlorination of ethylene to 1,2-dichloroethane. Figure 1 shows a loop reactor 1 with circulating EDC as the reaction medium, in which chlorine 2 and ethylene 3 are reacted to form 1,2-dichloroethane (EDC). The ethylene is fed in gaseous form into the lower part of the reactor riser 4 and dissolved in the circulating EDC. The chlorine 2 is dissolved in at least a portion 7 of the recirculating EDC 6, which is drawn from the reactor's downpipe 8 by means of a recirculating pump 9. Dissolution is carried out by means of a liquid jet gas compressor 10 or – if gaseous chlorine is available at sufficient pressure or liquid chlorine is used – by means of a static mixer (not shown here).The EDC partial stream 7 used to dissolve the chlorine is cooled to a temperature suitable for dissolving the chlorine by means of a heat exchanger 11 after prior cooling by the heat recovery measures according to the invention. Another partial stream 12 of the EDC cycle stream 6 is returned to the reactor downpipe without further cooling after cooling by the heat recovery measures according to the invention. Due to the heat of reaction, a portion of the EDC stream circulating in the reactor evaporates at the reactor head. This vaporous EDC stream 13 is condensed for heat recovery.

[0057] As further shown in Fig. 2, the vaporous EDC stream 13 from the reactor head is partially condensed in a first steam generator 14, releasing latent heat. The condensed liquid EDC stream 15 is fed to further processing, and the remaining gaseous stream 16, containing inert gases, is fed to a flue gas treatment system. Using the latent heat of the condensing EDC, circulating boiler feedwater 17 is partially vaporized in the steam generator 14. A first two-phase water stream 18 is fed to a first phase separation vessel 19. The water phase 20 is recirculated by a first pump 21. Fresh boiler feedwater is supplied via a line 22.

[0058] Hot circulating EDC 6 from the EDC circulating pump 9 transfers sensible heat to circulating boiler feedwater 20 in a second heat exchanger 23, causing some of the water to evaporate. The two-phase water flow 22 is fed to the phase separation vessel 19. The water phase 20 is recirculated, as already described, replenishing the evaporated quantity. The combined vapor phases from the separation vessel are compressed to a higher pressure by means of a compressor 26 with at least one stage. Boiler feedwater 25 is added to saturate the compressed steam. If a multi-stage compressor is used, saturation occurs after each compression stage. Compressed steam 27 is discharged to the system boundary for any desired use.

[0059] The compressed steam 27 produced by the compressor 26 preferably has a temperature and pressure level of at least 110°C and at least 1.43 bar(a), particularly preferably at least 150°C and at least 4.76 bar(a).

[0060] The EDC circuit partial flow 1, 7 transfers latent heat to circulating boiler feedwater 28 in a third heat exchanger 28, causing the boiler feedwater to partially evaporate. The two-phase water flow 29 is fed to a second phase separation vessel 30. The water phase 31 from the phase separation vessel 30 is recirculated by means of a second pump 32.

[0061] Since the EDC stream 7, which releases heat in heat exchanger 28, has already been cooled in heat exchanger 24, the steam separated in phase separator 30 has a lower pressure than the steam separated in phase separator 19. The steam from the second phase separator is compressed by means of a second, at least single-stage compressor 33 and fed into the suction side of the first compressor. Boiler feedwater 35 is added to saturate the compressed steam. If a multi-stage compressor is used, saturation takes place after each compression stage.

[0062] On the suction side of the first compressor 26, a temperature and pressure level of at most 90 °C and at most 0.7 bar(a) preferably prevails, while on the suction side of the second compressor 33 a temperature and pressure level of at most 65 °C and at most 0.25 bar(a) preferably prevails.

[0063] Depending on the operating mode and the desired degree of heat recovery, the EDC circuit flow can also be omitted as a division into partial flows 7 and 12. In this case, the EDC circuit flow 6 first flows through the heat exchanger 24 and then through the heat exchanger 28 (not shown in the figures).

[0064] The amount of vaporous EDC 13 evaporating and discharged at the reactor head during steady-state operation of the loop reactor 1 is determined by the amount of heat discharged via the EDC circuit 6. During steady-state operation of the loop reactor 1, the amount of EDC evaporating at the reactor head corresponds to the difference between the reaction energy and the amount of heat discharged via the EDC circuit 6. The amount of heat discharged via the EDC circuit 6 can be adjusted via the operating parameters of the heat recovery system, for example, the EDC circuit pump 9 and the heat exchangers 24, 28.

[0065] In particular, more vaporous EDC can therefore be discharged at the reactor head per unit of time than is produced in the same time during the chlorination reaction in loop reactor 1. In this case, a portion of the condensed liquid EDC 15 is returned to loop reactor 1, for example as part of stream 12, to enable steady-state operation.

[0066] However, at least the amount of EDC produced in the loop reactor 1 per unit of time is preferably extracted as vaporous EDC 13 overhead, and at least the amount of liquid EDC required for complete dissolution of the chlorine per unit of time is extracted via the side outlet as EDC recirculation stream 6.

[0067] 1 loop reactor

[0068] 2 Chlor

[0069] 3 Ethylen

[0070] 4 Reactor riser pipe

[0071] 5 Circulating EDC

[0072] 6 EDC - Circulating flow for chlorine dissolution and heat recovery

[0073] 7 EDC circuit partial flow 1

[0074] 8 Reactor downpipe

[0075] 9 EDC circulation pump 10 Liquid jet gas compressor / Static mixer

[0076] 11 heat exchangers

[0077] 12 EDC circuit partial flow 2

[0078] 13. Vaporous EDC from the reactor head

[0079] 14 steam generators 1

[0080] 15 Condensed Liquid EDC

[0081] 16 Exhaust gas flow, containing inert

[0082] 17 Boiler feedwater

[0083] 18 Two-phase water flow 1

[0084] 19 Phase separation tanks 1

[0085] 20 Boiler feedwater circulation flow, first circuit

[0086] 21 Boiler feedwater circulation pump 1

[0087] 22 Two-phase water flow 2

[0088] 23 Fresh boiler feedwater line

[0089] 24 steam generators 2

[0090] 25 Boiler feedwater for steam saturation, compressor 1

[0091] 26 Mechanical compressor 1

[0092] 27 Steam, compressed, to the plant boundary

[0093] 28 steam generators 3

[0094] 29 Two-phase water flow 3

[0095] 30 phase separation tanks 2

[0096] 31 Boiler feedwater circulation flow, second circuit

[0097] 32 Boiler feedwater circulation pump 2

[0098] 33 Mechanical compressor 2

[0099] 34 Boiler feedwater for steam saturation, compressor 2

Claims

P149516PC00 Patent claims 1. Apparatus for the production of partially chlorinated alkanes, comprising a loop reactor (1) having a first feed (3) for an alkene to be chlorinated, a second feed for a chlorinating agent (2) and a top-side discharge for a gaseous product stream (13) containing produced partially chlorinated alkane, characterized in that the gaseous product stream (13) is fed to a first heat exchanger (14) designed to at least partially condense partially chlorinated alkane of the product stream (13) and to at least partially evaporate water supplied via a first feed for water (17), wherein a stream (15) containing condensed partially chlorinated alkane and a gaseous stream (16) and a first two-phase stream (18) containing liquid and vaporous water are discharged from the first heat exchanger (14).

2. Device according to claim 1, characterized in that the first two-phase current (18) containing liquid and vaporous water is supplied to a first phase separation vessel (19) which is designed to separate the first two-phase current (18) into a first liquid water phase (20) and a first vaporous water phase.

3. Device according to the preceding claim, characterized in that the first phase separation vessel (19) has a top-side discharge for the first vaporous water phase, via which the first vaporous water phase is led to an outlet (27). 249 P 1852 4. Device according to the preceding claim, characterized in that the discharged first vaporous water phase is supplied to a first compression device (26) which is arranged upstream of the outlet (27), which is preferably a mechanical compression device and in particular comprises at least one compression stage.

5. Device according to the preceding claim, characterized in that the first compression device (26) has a second supply (25) for liquid fresh water.

6. Device according to one of claims 2 to 5, characterized in that at least a part of the liquid water phase (20) is removed from the first phase separation vessel (19), in particular from the bottom, and is supplied to the first heat exchanger (14) via the first water supply (17), wherein the removal is preferably carried out with a first pump (21).

7. Device according to one of the preceding claims, characterized in that the loop reactor (1) has a laterally arranged discharge of a liquid circulating stream (6) containing liquid partially chlorinated alkane, which is fed to a second heat exchanger (24) designed to cool liquid partially chlorinated alkane of the circulating stream (6) and to at least partially evaporate water supplied via a second inlet for water, wherein a return stream containing cooled partially chlorinated alkane and a second two-phase stream (22) containing liquid and vaporous water are discharged from the second heat exchanger (24).

8. Device according to the preceding claim, characterized in that the loop reactor has a rising zone (4) and a falling zone (8) and the discharge of the circulating flow (6) preferably takes place from the falling zone. 249 P 1852 9. Device according to one of the two preceding claims, characterized in that the discharge of the liquid circulating flow (6) is carried out by means of a circulating flow pump (9).

10. Device according to one of claims 7 to 9, characterized in that the second two-phase current (22) is supplied to the first phase separation container (19).

11. Device according to one of claims 7 to 10, characterized in that at least a part of the return stream is fed into a mixing device (10), wherein the mixing device (10) is designed to mix the chlorinating agent (2) with the partially chlorinated alkane of the return stream (7), and the mixture produced in the mixing device (10) is fed to the second feed for a chlorinating agent (2).

12. Device according to the preceding claim, characterized in that the return flow is split into a first partial flow (7) and a second partial flow (12), wherein the first partial flow (7) is supplied to the mixing device (10) and the second partial flow (12) is directed into the loop reactor (1), preferably into the fall zone (8), in particular below the extraction of the liquid circulating flow (6).

13. Device according to one of the two preceding claims, characterized in that a third heat exchanger (28) is arranged upstream of the mixing device (10), which is designed to cool the return flow or the partial flow (7) and to at least partially evaporate water supplied via a second water inlet, wherein a cooled return flow or the partial flow (7), containing further cooled partially chlorinated alkane and a third two-phase flow (29), containing liquid and vaporous water, is discharged from the third heat exchanger (28). 249 P 1852 14. Device according to the preceding claim, characterized in that the third two-phase current (29) is supplied to a second phase separation vessel (30) which is designed to separate the third two-phase current (29) into a second liquid water phase and a second vaporous water phase, wherein the second liquid water phase is preferably supplied to the third heat exchanger (28) via the second water supply.

15. Device according to the preceding claim, characterized in that the second phase separation vessel (30) has a top-side discharge for the second vaporous water phase, via which the second vaporous water phase is led to an outlet (27).

16. Device according to the preceding claim, characterized in that the discharged second vaporous water phase is supplied to a second compression device (33) which is arranged upstream of the outlet (27), which is preferably a mechanical compression device and comprises at least one compression stage.

17. Device according to the preceding claim, characterized in that the second compression device (33) has a second supply (34) for liquid fresh water.

18. Device according to one of claims 4 to 17, characterized in that the first compression device (26) and / or second compression device (33) are radial blowers.

19. Device according to one of claims 3 to 18, characterized in that at least one evaporator stage for evaporating sodium hydroxide is connected downstream of the outlet (27), which is designed to be heated by means of the first and / or second vaporous water phase or the combined first and second vaporous water phase.

20. Device according to the preceding claim, characterized in that the at least one evaporator stage is operated by means of a plate heat exchanger. 249 P 1852 21. Device according to one of the two preceding claims, characterized in that a decompression stage for sodium hydroxide is connected upstream of the evaporator stage, which is designed to pre-concentrate sodium hydroxide.

22. Device according to one of claims 3 to 18, characterized in that a system for the distillative desalination of seawater is connected downstream of the outlet (27), which is designed to be heated by means of the first and / or second vaporous water phase or the combined first and second vaporous water phase.

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