A method of processing products of fission by thermal decomposition of 1,2-dichloroethane

 

(57) Abstract:

The invention relates to the chemical industry and plastics. Processing of products of the cleavage of 1,2-dichloroethane carried out by cooling the gaseous products of up to 150-180oC. Prevailing neskondensirovannyh component part, consisting of the products of the cleavage of HCl and vinyl chloride and undecomposed 1,2-dichloroethane, sent for processing by distillation. Get 1,2-dichloroethane, which is sent to the chlorination of benzene without additional purification. The condensed part, containing all of the coke is subjected to a separate processing. The technical result is the improvement of technological and economic indicators. 3 C.p. f-crystals.

Scope:

Chemicals and plastics, where vinyl chloride is used as raw material for polyvinyl chloride and mixtures of polymerization.

Technical obtaining vinyl chloride is carried out by thermal cleavage of 1,2-dichloroethane at temperatures of 450-600oWith increased pressure. Approximately 40-65% of the 1,2-dichloroethane is split into vinyl chloride and hydrogen chloride. This Rasse is 2">

The fission products:

Target products: vinyl chloride and Hcl,

Not decomposed 1,2-dichloroethane.

By-products, which have a lower boiling point than the target products.

By-products, which have a higher boiling point than the target products, including solid by-products such as coke.

Thus, it is necessary to carry out multistage separation by distillation.

Gaseous products of thermal cleavage (gas splitting) is first sent through a filter to separate the coarser coke particles, is subjected to condensation and sent to the first distillation column (HCl-column), in which as the head product Argonauts hydrogen chloride. In the next column (column for vinyl chloride) as the head of product Argonauts the vinyl chloride. The lower part of the column contains undecomposed 1,2-dichloroethane, and whiter easily and higher boiling by-products and finer coke particles.

These coke particles especially interfere with the desired separation of benzene, so that up to now it was necessary (to produce) expensive office product lower Castine and partial purification was carried out by evaporation under reduced pressure.

From the Federal Republic of Germany patent DE-A-4033047 known way of separating benzene from the 1,2-dichloroethane obtained again in the manufacture of vinyl chloride, after separation of vinyl chloride and hydrogen chloride, which differs in that the 1,2-dichloroethane from the bottom of the column for vinyl chloride is separated into purified from high-boiling substances, the flow of the product and the crude product stream, the purified product stream is subjected to treatment with chlorine at a temperature of 30-85oWith the presence of metallic iron and this product flow again unite with untreated flow of the product together and separate the 1,2-dichloroethane from storable in the process of conducting further cleanup operations. The improvement of this method is that the catalyst used is aluminum oxide (the Federal Republic of Germany patent DE-A-4129391).

From the Federal Republic of Germany patent DE-A-4139632 known, then, a way to separate the benzene from the 1,2-dichloroethane obtained again in the production of vinyl chloride after the separation of vinyl chloride and hydrogen chloride, which is characterized by the fact that contaminated 1,2-dichloroethane from the bottom of the column for vinyl chloride is divided into free of high-boiling substances (Cu760> 83,7oC) the flow of the first product and containing high-boiling substances in the presence of metallic iron, the treated flow of the first product to combine with the flow of the second product, the combined flows of the product jointly processed with chlorine at a temperature of 30-85oFrom this stream of product produce purified in the distillation zone 1,2-dichloroethane.

From the Federal Republic of Germany patent DE-A-4132761 known method of gas processing cleavage, which is obtained as a by-product during thermal decomposition of 1,2-dichloroethane to vinyl chloride at a temperature of 480-540oC and a pressure of 15-25 bar and, if necessary, cooled with heat recovery to a temperature of 180-280oWith this temperature is sent to the zone of rapid cooling, in which he washed and cooled condensed gas cleavage, wherein a) 80-99 wt.% the cooled gases splitting in gaseous form as the head product and 1-20 wt.% the cooled gas as a liquid bottom product of the column is removed from the zone of rapid cooling, b) is contained in the bottom product of column area rapid quenching of the coke is crushed, resulting dispersion is separated in the separation zone to the distillate and the bottom product of the column, the bottom product of the column is withdrawn from the way through the gateway device condensation. Preferably 3-6 wt.% remove from the zone of rapid cooling as the bottom product of the column.

The task of the invention is as follows:

"A simplified method of producing vinyl chloride by thermal cleavage of 1,2-dichloroethane from the technological and economic points of view."

The purpose of the processing:

Formed during thermal decomposition of 1,2-dichloroethane gaseous products along with not decomposed 1,2-dichloroethane and the target products VC and HCl also contain high-boiling by-products and coke component. To protect distillation columns connected in series from dirt and especially to protect the catalyst for the chlorination of benzene from decontamination still were required costly cleanup operations for the Department of coke particles. Thanks to this invention, the method failed to convert and simplify it so that these cleanup operations can be waived.

It was found that the following principle areas of rapid cooling can be used in order to simplify the chlorination of benzene: you can refuse the separation of the flows of product and cleaning one of these otnositelno a narrow region of low temperature 150-180oWith, preferably 160-170oWith so at this stage condensation condense only a small proportion of 1,2-dichloroethane together with high-boiling components, and educated coke. A large part of undecomposed 1,2-dichloroethane, thus, with the products of the vinyl chloride and hydrogen chloride is sent to distillation under normal pressure, and is known in itself by the way - first, hydrogen chloride, and further steps of the vinyl chloride is separated from the 1,2-dichloroethane by distillation. The remaining 1,2-dichloroethane can now - without treatment - send in the unit for removal of benzene, which should be carried out according to the Federal Republic of Germany patent DE-A-4129391 with-aluminum oxide.

In the General case, it is sufficient only part of 1,2-dichloroethane to be subjected to the chlorination of benzene to maintain a fairly small part of benzene and its by-products in 1,2-ethylene dichloride or vinyl chloride. For division into partial flows quite the same, according to the invention, a simple device, such as regulating valve.

According to the invention can be condensing less than 7%, preferably less than 5% of the 1,2-dichloroethane so that it was necessary processing is passed at a known chlorination of benzene evaporation under reduced pressure disappears, so that the method according to the invention requires significantly less.

The invention is illustrated hereinafter in more detail by the following example.

Example

Gas splitting obtained in the process of decomposition of 1,2-dichloroethane, cooled with gas condensate splitting in the zone of rapid cooling to about 160-170oWith condensed 4% gas cleavage. The condensate is all coke. It disperses and is subjected to a separate processing.

Unfused approximately 96% of the gas splitting away in gaseous form through the head of the zone of rapid cooling, is directed to intermediate condensation and there subjected to condensation. This condensate is also sent to HCl-column. Followed by distillation in the HCl column for vinyl chloride products of the lower parts of the columns do not contain coke. The flow of product from the bottom of the column for vinyl chloride after cooling to about 30-50oUsing the regulating valve is divided into two partial flow: approximately 8 tons/hour go to the chlorination of benzene, about 20 t/h hold past the reactor chlorination of benzene and combined with the product from this reactor. The combined stream of product without cooling tra the attachment method according to the invention fall away, thus, part of the installation associated with a reduced pressure and filtered.

1. A method of processing products of fission by thermal decomposition of 1,2-dichloroethane, characterized in that the gaseous products are cooled to a temperature of 150-180oWith and prevailing neskondensirovannyh component part, consisting of the products of the cleavage model HC1 and vinyl chloride and undecomposed 1,2-dichloroethane, including therein the by-products are sent for processing by distillation and thus obtained 1,2-dichloroethane, including therein by-products, without additional purification sent to the chlorination of benzene condensed component part containing all of the coke is subjected to a separate processing.

2. The method according to p. 1, characterized in that the cooling is carried out until a temperature of 160-170oC.

3. The method according to p. 1 or 2, characterized in that condenses less than 7% of the gas cleavage.

4. The method according to one of paragraphs. 1-3, characterized in that the chlorination of benzene direct part of the flow undecomposed 1,2-dichloroethane.

 

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