Method for producing 1,2-dichloroethane by direct chlorination and installation for its implementation

 

(57) Abstract:

The invention relates to the production of 1,2-dichloroethane (ethylene dichloride , ejh) by introducing ethylene and chlorine in the circulating ejh under vigorous stirring and heat recovery. The interaction is carried out at a temperature of 65-125C and an absolute pressure of 0.5 to 3.2 bar. When this process is carried out in such a way as to ensure that the boiling of the reaction mixture, and the heat of reaction away from the filled gas space and send at least one heat exchanger. The process is carried out at the plant, including the reactor with a stirrer, a heat exchanger, preferably a distillation column, condenser, dryer. This increases the efficiency of monitoring the progress of the reaction, preventing the formation of side products, which lowers costs. 2 C. and 8 C.p. f-crystals, 3 ill.

The invention relates to a method for producing 1,2-dichloroethane by direct chlorination.

Obtaining 1,2-dichloroethane or ethylene dichloride, ejh) reaction of interaction between ethylene and chlorine, usually referred to as direct chlorination, flows with heat release. To improve the monitoring of the reaction and for removal of heat of reaction usually ispolzuyuschie raw ejh, and the heat of reaction is used, selecting it through the heat exchanger, for example a distillation column. Such methods are known, e.g. from EP-A-471987 (ZA 91/6491), DE-A - 4029314 and DE-A-4133810. From these publications it is also known the use of appropriate equipment such as stirrers without additional mixing devices, for particularly intensive mixing of the reagents with the circulating ejh. In the US 4873384 describes a method for ejh from ethylene and chlorine in a liquid ejh, vapors of the reaction medium used for the regeneration of part of the latent heat.

The present invention relates to a method for ejh by introducing ethylene and chlorine in the circulating ejh under vigorous stirring and heat recovery. This method differs in that the interaction is carried out at a temperature of 65 - 125oC and an absolute pressure of from 0.5 to 3.2 bar, and the pressure and temperature is chosen so to ensure that the boiling of the reaction mixture, and the heat of reaction away from the gas stream and directed into the heat exchanger.

The invention further relates to an apparatus for carrying out the method, the scheme of which is shown in Fig. 1. In this drawing under the relevant positions obozny pipeline for liquid ejh,

5 - pump,

6 - supply pipe for chlorine, respectively, of ethylene,

7 - supply line for ethylene, chlorine respectively,

8 - the discharge pipe for the gaseous reaction mixture,

9 - piping to the heat exchanger 10,

10 - heat exchanger

11 - the return pipe from the heat exchanger 10 to the reactor 1,

12 - pipeline to the distillation column (shown),

13 - pipeline to the consumer of heat, respectively, of the heat consumer,

14 - the pipeline from the heat consumer, respectively, to the heat consumer.

Preferred embodiments of proposed according to the invention method, accordingly, embodiments of the offer according to the invention the installation described in more detail below.

According to one of embodiments of the method of the filled gas space divert the gaseous reaction mixture, ejh condense in the heat exchanger and liquid ejh return to the reactor.

In accordance with another embodiment of the invention the gaseous reaction mixture is introduced laterally in a distillation column, from which the top assign inert gas components and neproreagirovavshimi products. For this distillation column, it is preferable to use the heat of reaction is removed from a filled gas space of the reactor. The temperature in the lower part of the distillation column while slightly below the temperature in the reaction space. For example, it is 90oC if the reaction is carried out at 105oC.

Installation suitable for the implementation of this variant of the invention shown in Fig. 2. In this drawing positions 1-14 indicated above items, and other items indicated the following elements:

15 - distillation column,

16 - pipeline for highly volatile products

17 - condenser,

18 - the circulation pipeline,

19 - tank phlegmy,

20 - pump

21 - the pipeline to drain boiling products,

22 - dryer

23 - pipe for the exhaust gas,

24 - condenser,

25 - pump

26 - pipeline for ejh,

27 - pipeline for high-boiling products.

Volatile products from the upper part of the distillation column 15 through the pipe 16 and through the condenser 17 is coming through the circulation pipe 18 into the tank 19 tank phlegmy). The condensed isoplane in this circuit is taken away by water, causing corrosion. Pipeline 21 volatile products can be displayed separately.

From the reservoir 19 gaseous products, mainly unreacted ethylene and inert components served by the pump 25 through one capacitor 24 for processing exhaust gases.

Dryer 22 may be performed in the usual manner and to operate, for example, based on the known physical and/or chemical principles. Dryer 22 may also contain a desiccant, which can be used either chemical desiccants such as patikis phosphorus, or physical desiccants such as molecular sieves or silica gels. The drying preferably takes place according to the method described in US 5507920.

In another embodiment of the invention the distillation column operates at low pressure. This option is shown in Fig. 3. In the drawing positions 1-21 (dryer 22 is absent) and 23-27 indicated above elements, and position 28 marked the return pipe from the condenser 24 to the reservoir 19.

When this tank 19 is under lower pressure in comparison with the column 15 (for example, the absolute pressure in the column 15 is 0.8 bar, and the tank 19 Abir, with the help of the pump 25 (using appropriate valves, which are not shown). In this embodiment, the tank 19 is decompression coming into it from the refrigerator 17 products. The gas phase flows through the pipe 23 in the refrigerator 24, from which liquefied products through the pipeline 28 back to the reservoir 19. The liquid phase, i.e., pure ejh, after passing through the pump 20 is divided into a stream of final products (exhaust pipeline 26) and the thread 18 is returned to the cycle of products.

The method is carried out using conventional catalysts. Use may be made of a Lewis acid such as ferric chloride (III), in combination with halides of metals of the first or second main group of the Periodic system of elements, primarily sodium chloride, in various molar ratios (NL-A-6901398, US 4774373 or DE-A-4103281), in particular, it is possible to apply the catalytic system described in WO 94/17019 (ZA 94/0535), in which the molar ratio between sodium chloride and iron chloride (III) in the course of the reaction remains below 0.5, is preferably from 0.45 to 0.3. In this way ejh get such a high purity that significantly increases the service life of heat exchangers.

Pteryx can highlight the following.

The reaction may proceed with a high degree of reliability and ensuring effective control over the course of its flow at any point in time. Due to this, the reaction temperature can be maintained at a low level, which suppresses the formation of by-products. In addition, due to the removal of the heat of reaction of the gaseous reaction mixture, the heat exchangers, for example coil evaporators, you can run small in size because it also uses the heat of condensation ejh. Another advantage is that the heat exchangers are not contaminated carried along with the flow of catalyst and high boiling by-products.

Highly efficient use of the heat of reaction and condensation allows for a greater freedom of choice in a constructive design method. Not only is the heat exchanger or heat exchangers can be placed directly next to the reactor, but also consuming heat apparatus, in turn, can be mounted spatially adjacent to the heat exchanger (heat exchanger), respectively around him (them). This prevents too high costs for the establishment of relevant structures, as well as eliminates th the di in the installation.

In the above embodiments of the invention, which are provided for the removal of inert components in the gas and unreacted ethylene, ethylene can in a known manner to separate from the inert components and return to the process. Such gas components such as oxygen or nitrogen, are made in the process, for example, together with chlorine, and in this case, the oxygen volume concentration below the explosive limit (3%) is considered to be inert. The return of exhaust gases by direct chlorination described in WO 96/03361 (ZA 95/6058).

In General, the reaction is carried out according to well-known technology, and the content of the above-mentioned literature sources, including on individual parts of the equipment included in the present description by reference.

Proposed according to the invention the method is illustrated in more detail by the following examples of its implementation.

Example 1 (Fig. 1 and 2)

In the reactor 1 direct chlorination, equipped with a stirrer 2 without additional mixing devices via the pipeline 6 is injected chlorine, and the pipe 7 serves ethylene. The reactor is filled up to level 3 liquid ejh, which is pumped in a closed loop in line 4 by pump 5. Big h is it mainly ejh, as well as trace amounts of unreacted ethylene, oxygen, nitrogen and more low-boiling in comparison with ejh components) is supplied to the pipe 9 into the heating column (heat exchanger 10, where it condenses, and the pipeline 11 is again directed into the reactor 1. The energy of condensation on the pipes 13 and 14 is fed to the distillation column 15, respectively, is taken away from her.

The smaller part of the gas mixture is introduced through the pipeline 12 at the side of the distillation column 15, in which unreacted ethylene, oxygen, nitrogen, and trace amounts of more low-boiling by-products, such as ethylchloride and water are separated in the upper part of (and are discharged through the pipeline 16). Clean ejh is taken from columns 15 through the pipeline 26 (below the point of entry of the supply pipe 12).

Such substances as ethylene, oxygen and nitrogen are passed through the pipeline 16, the capacitor 17, condenseries in it, the pipe 18, the reservoir 19 and the pipe 23 and into the condenser 24 of the exhaust gases, and then arrive at the compressor 25, which conveys them to the treatment plant off-gases.

Substances such as more low-boiling by-products and consisting of ejh and the second pipe 18, first go into the tank 19 to phlegmy, but there pumping the pump 20 is fed to the dryer 22, which prevents the accumulation in the upper part of the column of water made it in trace quantities. The dried condensate then flows through the circulation pipe 18 to a distillation column 15.

Example 2 (Fig. 3)

Working analogously to example 1, first paragraph, however, then the process is as follows.

A smaller part of the gas mixture through the pipeline 12 is introduced into the distillation column 15. Clean ejh, and unreacted ethylene, oxygen and nitrogen and trace amounts of more low-boiling components are fed via pipe 16 in ejh-capacitor 17, and then through pipe 18 into the reservoir 19 to phlegmy. With one (only) vacuum pump 25 absolute pressure in the column 15 is set to a value of 0.8 bar, and the tank 19 to phlegmy bring up the level of 0.26 bar with the intention of separating unreacted dissolved in ejh ethylene, and oxygen and nitrogen. In the refrigerator 24 of exhaust gases at a temperature of +1oC there is a further condensation ejh, while exhaust gases are fed via line 23 to install their processing. Clean ejh from rezeigat (ethylene dichloride, Ejh) by introducing ethylene and chlorine in the circulating ejh under vigorous stirring and heat recovery, characterized in that the interaction between ethylene and chlorine is carried out at a temperature of 65 - 125oC and an absolute pressure of 0.5 to 3.2 bar, and the pressure and temperature is chosen so to ensure that the boiling of the reaction mixture, and the heat of reaction away from the filled gas space and send at least one heat exchanger.

2. The method according to p. 1, characterized in that the filled gas space divert part of the gaseous reaction mixture, ejh condense in the heat exchanger and liquid ejh return to the reactor.

3. The method according to p. 1 or 2, characterized in that part of the gaseous reaction mixture is introduced laterally in a distillation column, from which the top assign inert gas components and unreacted ethylene, the side below the entry of the reaction mixture are selected net ejh, and from Cuba to separate high-boiling by-products.

4. The method according to p. 3, characterized in that the distillation columns use the heat of reaction from the filled gas space of the reactor.

5. The method according to one or more of the preceding paragraphs, living devices.

6. The method according to one or more of the preceding items, characterized in that the reaction is carried out using a catalytic system consisting of a Lewis acid and the halide of the metal of the first or second main group of the Periodic system of elements.

7. The method according to p. 6, characterized in that the catalyst used sodium chloride and iron chloride (III) in a molar ratio of less than 0.5.

8. Installation for implementing the method according to PP.1 to 7, characterized by the presence of the reactor (1), mixer (2), level (3) liquid ejh, the circulation pipeline (4) for liquid ejh, pump (5), the inlet pipes (6, 7) for chlorine, respectively, of ethylene, and a discharge pipe (8) for the gaseous reaction mixture, pipe (9) to heat exchanger (10), a heat exchanger (10), the return pipe (11) from the heat exchanger (10) to the reactor (1), pipeline (12) to the distillation column and conduits (13, 14) to the consumer of heat, respectively, of the heat consumer.

9. Installation under item 8, characterized by the presence of the distillation column (15), pipe (16) for volatile products, condenser (17), the circulation pipeline (18), tank (19) for phlegmy, pump (20), pipe (21) to remove the node (26) for ejh and pipeline (27) for the high-boiling products.

10. Installation under item 9, characterized in that there is no dryer (22) and a return pipe (28) from the condenser (24) to the tank (19).

Priority points:

04.07.96 on PP.1 to 5, 7 and 8;

09.10.96 on PP.6, 9 and 10.

 

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