The method of obtaining pure benzene and pure toluene and device for its implementation

 

(57) Abstract:

The invention relates to a method for production of pure benzene and pure toluene from the original product containing aromatic hydrocarbons, and the original product in the stabilization process step of distillation (1) free from gases, and stable source product is divided into an intermediate product, enriched with benzene, and the intermediate product, enriched with toluene, and the intermediate product, enriched with benzene, and the intermediate product, enriched in toluene, send in process stage extractive distillation (2) and separately issued on different plates of the column for extractive distillation (4), and a mixture of pure benzene, pure toluene and extracting agent selected from the lower part (3) of the column for extractive distillation (4) and with the extracting agent in the Stripping process stage (5) is separated from pure benzene and pure toluene and return in process stage extractive distillation (2). It differs in that the stabilization process stage distillation (1) is equipped to separate the original product intermediate product, enriched in b the config benzene, sent directly from the stabilization process step of distillation (1) in process stage extractive distillation, and, on the other hand, the intermediate product, enriched in toluene, before serving in process stage extractive distillation (2) in process stage preliminary distillation (6) release from the high-boiling components. The technical result - increase in the efficiency of the process and the purity of the target product. 2 C. and 8 C.p. f-crystals, 1 Il., table 1.

The invention relates to a method for production of pure benzene and pure toluene from the original product containing aromatic hydrocarbons, in which the original product is free from gases in the stabilization process step of distillation, where stable source product is divided into an intermediate product, enriched with benzene, and the intermediate product, enriched with toluene, and then the intermediate product is enriched with benzene, and the intermediate product, enriched in toluene, send in process stage extractive distillation and separately served on different plates of the column for extractive distillation, in which a mixture consisting of pure benzene, pure toluene is NT in the technological level of the steam is separated from pure benzene and pure toluene and return to the stage extractive distillation. Under pure benzene and pure toluene is assumed that the benzene and pure toluene in a technical sense, i.e., that can be a small amount of contamination by impurities. As the original product containing aromatic hydrocarbons, typically use coke crude benzene from the process of coking coal and/or pyrolysis gasoline from the oil refining process. Mainly, however, is also used, for example, annealing the benzene from the process of aeration of coal or oil or catalytic reforming product of the oil refining process. These initial products contain a greater part of the residual gas from the process of manufacture of the original product. Such residual gases can be, for example, hydrogen sulfide, ammonia and hydrogen. In this case we speak of unstabilized source products. Unstabilized source product should, however, before further processing to be stabilizing, i.e., free from residual gases, so that couldn't have place for further processing of any harmful reactions. This is done in the stabilization process step of distillation. This unstabilized original product is served in the stabilization of the columns of the output products is lowered into the lower part of the column. During the steps of the method according to extractive distillation in the column for extractive distillation, along with bursting discs intermediate products or product, served selective solvent with polar groups as the extracting agent, as a rule, the head of the column for extractive distillation. Due to this, the partial pressure of neuromata increase stronger than the partial pressure of fragrances, and thus contribute to the associated separation in the column for extractive distillation. Neuropathy taken from the head of the column for extractive distillation and disposed. Extracting agents dissolved therein flavors of fall in the lower part of the column for extractive distillation. Stage Stripping unit uses a suitably equipped ferry column for separation of the extracting agent and fragrances. Thus obtained mixture of benzene and toluene is almost completely without interference divided into its components.

The method specified first type is known from practice and is basically described in the source EP 0 434 959 A2. According to this literature, the separation of stable original product on p ferry column, moreover, the intermediate product, enriched with benzene, is withdrawn from the head of ferry columns, and the intermediate product, enriched in toluene is withdrawn from a side exhaust ferry columns, while parts of the original product with a high boiling point fall in the lower part of the column and disposed of it. In practice, known to some extent the way to the ferry column pre-connects the stabilization stage distillation normal appearance. This method is mostly paid off, however, in regard to the purity of the obtained benzene and toluene can still be improved, since only part of the non-aromatic hydrocarbons in benzene is almost 0.1% in toluene nearly 0.2 percent.

From a literary source DE 15 43 119 A1 is known a method other for the production of benzene and toluene from the original product containing aromatic hydrocarbons, which produces a very pure benzene, however impure, containing about 1.5% by weight of non-aromatic hydrocarbons toluene. This method works with a single first stage of distillation, in which boiling at temperatures above 150oC components are separated from the stable is and the only plate column for extractive distillation. In practice, this method is improved due to the fact that step of the process of extractive distillation works intermittently, and described the way from time to time interrupted in order received impure toluene using stage of the process of extractive distillation to free from harmful nah. The result is very pure benzene, and very pure toluene; the disadvantage, however, is that due to the intermittency of the process requires a large capacity for interim storage of pre-cleared original product or impure toluene. This incurs costs. In addition, this intermittent method is unfavorable in energy terms, since it requires a larger amount of high-pressure steam. Instead of intermittent operation method can be equipped also the second step of the process of extractive distillation for additional processing impure toluene. It is, however, very expensive.

In contrast to the specified first prior art, the basis of the invention lies in the technical task of creating a method of obtaining pure benzene and pure toluene from the original product containing aromatic hydrocarbons, wherein phlebodium, namely, without significantly increasing costs.

To solve this technical problem the invention reports that are equipped with the stabilization process stage distillation for the separation of the original product intermediate product, enriched with benzene, and the intermediate product, enriched with toluene, and that, on the one hand, intermediate product, enriched with benzene, directly served from the stabilization process step of distillation in stage extractive distillation, and on the other hand, the intermediate product, enriched in toluene, before serving in the stage extractive distillation is released from the high-boiling components in the technological stage of the preliminary distillation. The invention uses data that already available technological level stabilization distillation can be designed not only to remove residual impurity gases, but also for the simultaneous separation of the original product intermediate product, enriched with benzene, and the intermediate product, enriched in toluene. Thanks to that used in other cases to separate the original product process stage distillation can be the t of the high-boiling components. Besides process stage preliminary distillation can be constructed with smaller dimensions, due to the small quantitative flow. The result is very pure benzene and a very pure toluene in a continuous process, i.e., without the need for costly storage tanks for intermediate storage, and without the need for additional process steps extractive distillation. The result is a final product of higher purity at almost the same cost. Energy consumption, in comparison with the closest prior art, remains basically the same. In General, using the process according to the invention results in unexpected synergistic effect, as is usually the improvement of the purity of the final product, especially when the already high level of purity can only be achieved with a considerable increase in cost.

The subject invention, however, is also a device for carrying out the method, which includes the stabilization column with a side outlet for releasing gas from the source of the product and to separate the original product enriched benzene and enriched in toluene products; to Gasanova toluene intermediate product from the high-boiling components, column for extractive distillation for filing an intermediate connecting the two terminals to the side outlet of the stabilization of the column and to the head of the column prior to distillation, and to the lower part of the column for extractive distillation column connected to steam, and from the bottom of the Stripping column can be removed extracting agent and sent to the supply pipe for extracting agent column for extractive distillation and from the head of the Stripping column can be removed mixture of pure benzene and pure toluene. Other embodiments of the device according to the invention described in claims 9 and 10.

Further, the device according to the invention, and carrying with it the way explained in more detail based on the drawing, which shows only one embodiment of the invention. The drawing schematically shows the construction of the device according to the invention.

In the drawing, first of all shows that are mainly used stabilization process stage distillation 1, process stage preliminary distillation 6, process stage extractive the process stage distillation 1 mainly has a stabilization column 8 with a side outlet 9. The stabilization column intended for the release of the original product from the gases and to separate the original product intermediate product, enriched with benzene, and the intermediate product, enriched in toluene. It contains about 60 practical plates, and a side outlet 9 is equipped at about 52nd practical plates. Process stage preliminary distillation 6 has a pre-column distillation 11 to release the intermediate product, enriched in toluene, from high-boiling components. Column a preliminary distillation 11 is equipped with approximately 65 practical plates. It is connected to the lower part 10 of the stabilization of the column 8. Part of the production stage extractive distillation 2 is equipped with a column for extractive distillation 4. Column for extractive distillation 4 for supplying the intermediate product 12, 13 connected by two connections to the side outlet 9 stabilizer 8 and the head part 14 of the column for preliminary distillation 11. It has about 70 theoretical plates, and a connection for supplying the intermediate product 13 for the intermediate product, enriched in toluene connected about /on/ 20 Teoret the product 12 to the intermediate product, enriched with benzene, there are about 17 // 40 theoretical plates below the feed pipe extracting agent. Between the connections of the supply of intermediate products 12, 13 can be equipped in the usual way fireplace plate columns. Process stage steam 5 includes a Stripping column 15, which is connected to the lower part 3 column 4 for extractive distillation. From the lower portion 16 of the Stripping column 15 can be removed extracting agent and sent to the supply pipe for extracting agent 17 column for extractive distillation 4. From the head part 18 of the Stripping column 15 can extract a mixture of pure benzene and pure toluene. Process stage separation is formed in the main distillation column 19 with about 60 practical plates. Distillation column 19 is connected to the head part 18 of the Stripping column 15. From the bottom of the distillation column 20 19 can be removed pure toluene, and from the head part 21, a distillation column 19 - pure benzene.

The drawing shows no sign several heat exchangers, as well as reflux columns. They can easily calculate and to equip the average person. P is tion according to the invention is claimed method is as follows. The original product in the stabilization process step of distillation 1 is released from the gases. When this stabilization process stage 1 is equipped with a distillation to separate the original product intermediate product, enriched with benzene, and the intermediate product, enriched in toluene. This is due to the fact that the intermediate product, enriched in benzene, extracted through the side outlet of the stabilization of the column 8 and the intermediate product, enriched in toluene, extracted from the lower part 10 of the stabilization of the column 8. When this stabilization process stage distillation 1 provides an intermediate product, enriched in toluene with a content of from 10 to 40% benzene, preferably about 20% /5%/ benzene. It has the same value provided that is contained in the original product methylcyclohexane up to 70% goes into the intermediate product, enriched in toluene. Enriched with benzene intermediate product directly from the stabilization process step of distillation 1 is sent in process stage extractive distillation 2. Enriched with toluene intermediate product before serving in process stage extractive plumage and this process stage preliminary distillation 6 runs thus, components with a boiling point of more than about 120oC are separated from the intermediate product, enriched in toluene. These components are mainly aromatic hydrocarbons with more than 7 atoms, as well as higher non-aromatic hydrocarbons. In the technological stage of the extractive distillation 2 processing is performed with N-formylmorpholine as extracting agent. The alternative is, however, also another substance from the group of N-substituted of the research, the substituents of which are less than 8 atoms, or a mixture. This extracting agent is known, for example, from a source patent DE 15 68 940 C3. Extracting agent is introduced into the upper part of the column for extractive distillation 3. A mixture consisting of pure benzene and pure toluene and extracting agent is extracted from the bottom of the column for extractive distillation 4. In the process step of steaming 5 extracting agent is separated from pure benzene and pure toluene and returns to step 2 for extractive distillation. A mixture of pure benzene and pure toluene, extracted from the process steps of steaming, is divided into its components, i.e., pure benzene and pure toluene, technologiesmountain experiments, carried out according to the method according to the invention and the method according to the literary source EP 0 434 959 A2, Dali amongst the results, given in the end of the text in the table, where

BY means of non-aromatic hydrocarbons. In respect of benzene shows that not only significantly increases the purity of the benzene, but what an unexpected way at the same time it is possible to ascertain the increase in output. This, in particular, is also important because of the loss of benzene must be removed from waste gases from considerations of environmental protection, which requires costs. These costs fall with increasing output and, consequently, in reducing losses. Moreover, the benzene talking about substance more "valuable" than with toluene. In respect of toluene can be stated that achieved a noticeable improvement in the cleanliness. At the same time, however, slightly lower output. Comparison of both methods in terms of cost of equipment and energy do not show any significant difference.

Comparison of the method according to the invention described in the beginning of the continuous method according to the literary source DE 15 43 119 A1 shows that although the achievable purity benzene or toluene comparable, the cost of the equipment in the way soglasno same for the claimed process requires approximately one-third less expensive high-pressure steam.

1. The method of obtaining pure benzene and pure toluene from the original product containing aromatic hydrocarbons, comprising the following stages: the initial product in the stabilization process step of distillation (1) free from gases, stable source product is divided into an intermediate product, enriched with benzene, and the intermediate product, enriched in toluene, intermediate product, enriched with benzene, and the intermediate product, enriched in toluene, send in process stage extractive distillation (2) and separately served on different plates of the column for extractive distillation (4), a mixture of pure benzene, pure toluene and extracting agent is extracted from the lower part (3) of the column for extractive distillation (4) and extracting agent in the process step of steaming (5) is separated from pure benzene and pure toluene and return in process stage extractive distillation (2), characterized in that the use of the stabilization process stage distillation (1) designed to separate the original product intermediate product, enriched with benzene, and the intermediate product, enriched with toluene and enriched benzene which are in process stage extractive distillation

(2) as an intermediate product, enriched in toluene, before sending in process stage extractive distillation (2) release from the high-boiling components in the technological stage of the preliminary distillation (6).

2. The method according to p. 1, characterized in that the intermediate product, enriched with benzene selected from the stabilization column (8) of the stabilization process step of distillation (1) through the side outlet (9), and the intermediate product, enriched with toluene, taken from the lower part (10) stabilizer (8).

3. The method according to p. 1 or 2, characterized in that the stabilization process stage distillation (1) works with the arguments provided to the content of benzene in the intermediate product, enriched in toluene, from 10 to 40%, preferably about 20%.

4. The method according to one of paragraphs.1 to 3, characterized in that the process stage preliminary distillation (6) works with parameters, which provides separation of components with a boiling point of more than 120oWith the intermediate product, enriched in toluene.

5. The method according to one of paragraphs. 1 to 4, characterized in that as the extracting agent is used as a compound from the group of N-substituted is.

6. The method according to one of paragraphs.1 to 5, characterized in that column for extractive distillation (4) from about 70 theoretical plates served intermediate product, enriched in toluene of about 20 theoretical plates below the pipeline for filing extracting agent and the intermediate product, enriched with benzene, served about 40 theoretical plates below the pipeline for filing extracting agent.

7. The method according to one of paragraphs.1 - 6, characterized in that a mixture consisting of pure benzene and pure toluene, extracted from the production stage Stripping unit (5), separated in the separation process of step (7) on its components.

8. Device for obtaining pure benzene and pure toluene, representing successively interconnected stabilization column, the column pre-distillation column for extractive distillation, a Stripping column and a distillation column, characterized in that the stabilization column (8) is equipped with a side-wall (9) to release the original product from the gases and to separate the original product intermediate product, enriched with benzene, and the intermediate product, abogado) to release the intermediate product, enriched with toluene, from the high-boiling component column for extractive distillation (4) connected by two connections for the supply of intermediate products (12, 13) to the side outlet (9) stabilizer (8) to the upper part (14) of the column prior to distillation (11) and to the lower part of the column for extractive distillation (4) connected to a Stripping column (15), and from the bottom of the Stripping column can be extracted extracting agent and served in the pipeline for extracting agent (17) column for extractive distillation (4), and from the upper part (18) Stripping columns (15) can be extracted as a mixture of pure benzene and pure toluene.

9. The device under item 8, characterized in that the stabilization column (8) has about 60 practical plates, and a side outlet (9) is situated at about 52nd practical plates and pre-column distillation (11) is approximately 65 practical plates, column for extractive distillation (4) has approximately 70 theoretical plates, and a connection for supplying the intermediate product (13) for the intermediate product, enriched in toluene, is lower by about 20 theoretical plates of the pipeline to supply ekstrasensov benzene, below about 40 theoretical plates pipeline for supplying extracting agent (17).

10. The device under item 8 or 9, characterized in that the upper part (18) Stripping columns (15) connected to a distillation column (19) with about 60 practical plates, and the lower part (20) of the distillation column (19) can be selected pure toluene, and from the upper part (21) of the distillation column (19) pure benzene.

 

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