Method of extraction of benzene from vysokoorientirovannogo raw materials

 

(57) Abstract:

Usage: in the petrochemical industry. Essence: allocation of benzene of high purity from vysokoorientirovannogo raw materials containing benzene, toluene and mixtures of saturated hydrocarbons. The process is carried out in two stages. In the first stage, allocate admixture of saturated hydrocarbons in heat and mass transfer apparatus containing a nozzle, made in the form of redistribution and heat and mass transfer packages built from specially shaped mesh in Z-educated bumps. The specific surface of the package 200 - 600 m2/m3and other design parameters chosen so as to provide a pressure differential between the top and bottom of the apparatus 10 to 80 mm RT. senior Process is carried out in the presence of a separating agent (RA) of aromatic hydrocarbons WITH8-C9when the mass ratio of RA - saturated hydrocarbons (3 - 60) : 1. Target benzene (purity of 99.96 wt.% and the output of 97.3 wt.%) allocate the second stage distillation top product, and from the lower product of the first stage. 1 C. p. F.-ly. table 1.

The invention relates to chemical processing of petroleum products, namely the extraction of benzene high sapolu brand benzene highest purification", used in the production of fibers, detergents and number of chemical syntheses, special requirements: the concentration of the basic substance shall be not less than 99,90 wt. the impurity content of saturated hydrocarbons in him should not exceed 0.10 wt. including n-heptane is not more than 0.01 wt. including n-heptane is not more than 0.01 wt. methylcyclohexane not more than 0.05 wt. Methylcyclopentane not more than 0.02 wt.

The benzene of high purity is mainly obtained by the catalytic reforming of gasoline fractions, followed by extraction with selective solvents such as triethylene glycol, N-organic and others.

A known method of extraction of benzene from mixtures with non-aromatic hydrocarbons by extractive distillation using as the separating agent amides of low molecular weight acids, in particular of dimethylformamide and dimethylacetamide [1]

The disadvantage of this method, in addition to the high rates of these agents is their chemical instability at high cycle use. Even in the presence of atmospheric moisture, they are able to decompose with the release of acids that cause corrosion of equipment and pollution target of benzene, which is unacceptable for holding the admixture of saturated hydrocarbons, by means of extractive distillation in the presence of a separating agent [2] as a separating agent use technical mixture of dioxane alcohols, taken in the mass ratio of the raw material (4-8):1.

The rectification is carried out at a multiplicity of irrigation 10-15 and atmospheric pressure. As distillate emit a mixture of saturated hydrocarbons and benzene. CBM product columns are referred to as power column efficiency 20 tons tons, on top of which is at atmospheric pressure, the temperature of the top 80aboutWith the expansion of irrigation 1,0 allocate target benzene of a purity of 99.9 wt. with the output from the potential to 95.5 wt.

The disadvantage of this method is the consumption of the process (per 1 ton of raw material is injected 4-8 t separating agent), the high cost of the latter, the significant cost of shipping from factories for the production of synthetic rubber. In addition, its use requires the complete absence of water impurities in raw materials. Otherwise, the cube of the column at a temperature of 205about(Example 1 of the prototype method) are hydrolytic processes with the formation of oxygen-containing impurities entering the benzene, i.e., the target product that meets the requirements of GOST cannot be allocated (see examples 9 and timesi water. Thus, according to the report Kirishi refinery, the concentration of water in basolateral fraction ranges from 0.07 to 0.14 wt.

The purpose of the invention increase the yield and quality of allotted benzene.

This goal is achieved by separating the benzene from vysokoorientirovannogo raw material containing impurities of saturated hydrocarbons by division in heat and mass transfer apparatus (abbreviated as TMA), equipped with heat and mass transfer and redistribution packages of specially shaped grid in the form of Z-shaped bumps with transverse waves, as well as special devices for uniform distribution of liquid and gas over the cross section of the device [3 and 4]

This is a relatively recently developed type of mass-transfer apparatus. Unlike disc distillation columns, which uses a bubble-way interaction of gas vapours and liquids in the TMA combined film as a mode of interaction flows rising steam from flowing liquid, and emulational mode, in which the flowing fluid due to the high velocity steam is broken into tiny droplets, turbulize stream. The liquid flows over the surface of the grid, and the grid cell size is chosen such film. Steam flow rises by inclined, overlapping channels have a spatial configuration, and is evenly distributed throughout the cross-section of the device.

Distribution packages are below the irrigation device and provide a uniform distribution of the liquid in the upper part of heat and mass transfer packages. From the uniformity of liquid distribution over the entire height of the column essentially depends on the efficiency of TMA. The disadvantage of existing distillation columns compared with the TMA is the need to enter additional redistributive device, which complicates the design and increases the height of the columns.

In this design of heat and mass transfer packages in each layer are redistributive and masloobmennye zone. Thus, by reducing the internal distribution of devices simplifies the design of mass transfer equipment.

TMA is considerably higher than a conventional distillation column, the throughput of liquid and gas, low hydraulic resistance at higher indexes of efficiency of the separation process.

Cleaning the ve which use aromatic hydrocarbons WITH8-C9taken in the mass ratio of a separating agent saturated hydrocarbons (3-60):1.

On top of TMA at a temperature 78-87aboutTo produce a mixture of hydrocarbons and uniform quantity of benzene. The bottom product of the TMA are separated in a distillation column efficiency 20-30 so t working with the multiplicity of the irrigation of 2.5-3.5, at a temperature of top 82-87aboutWith, the bottom 134-140aboutC. as a result, the top of the column produce the target product, on the bottom a mixture of toluene with a separating agent.

The bottom product of the column selection target benzene enters the next distillation column efficiency 20-30 so t working with the multiplicity of the irrigation of 1.5 to 2.5, the temperature of the top 112-120aboutWith, the bottom 155-170aboutC. the Top product of the column allocate commodity toluene, at the bottom of a separating agent, which recycle the power of the TMA, i.e. the problem of regeneration of the separating agent in the proposed method is solved quite simply.

The separation process in a TMA shall exercise so that the differential pressure between the upper and lower points of the device was in the range of 10-80 mm RT.article The specified differential is achieved by regulating the number of termoemissionnykh packages, as well as some of the Reticuli.

For the achievement of the invention objectives will be essential to the value of specific surface area of heat and mass transfer packages.

This value should be in the range of 200-600 m2/m3. Failure to comply with specified ranges of differential pressure and specific surface indicated the purpose of the invention is not achieved.

It is established that the purification of benzene from impurities saturated hydrocarbons in the presence of a separating agent flows significantly more effective than the in tray and Packed distillation columns, and the requirements of GOST in benzene can be achieved.

The recommended ratio separating agent admixture of saturated hydrocarbons is (3-60): 1. With a ratio of < 3:1, benzene, meets the requirements of GOST cannot be determined.

A ratio greater than 60:1, it is impractical from a technical-economic point of view, since in this case the energy consumption increases and the diameter of the TMA, and the yield and purity of the target product with virtually no change.

Thus, the important features of the proposed method is the process benzene purification from impurities saturated hydrocarbons in TMA with peripatoi separating agent of aromatic hydrocarbons WITH8-C9when the mass ratio in the feeding apparatus of a separating agent admixture of saturated hydrocarbons (3-60):1.

The possibility of benzene purification from impurities saturated hydrocarbons in the TMA using the separating agent is not an obvious fact and cannot be predicted from published data and theoretical calculations. Moreover, for example, it is impossible to clear the proposed method, the benzene from impurities olefin, diene and cycloolefinic hydrocarbons. This requires other separating agents and techniques to support the process.

The proposed method for the selection of benzene implement on an industrial scale, because in Russia there are companies that have started to produce TMA wide performance range.

Thus, the proposed method can improve the purity of the emitted benzene with 99,84 to 99.96 wt. the potential output from 95.5 to 97.3 wt.

The method is illustrated by the examples, the main results of which are shown in the pivot table.

P R I m e R 1. Hydrotreated straight run gasoline fraction, wikipaedia at a temperature of 62-95aboutC, isolated from the Samotlor oil field and containing non-aromatic uglevodorodami, containing, by weight.

Platinum 0,6

Chlorine 0,7

Rhenium 0,09

Cadmium 0,6 zulfikarovna alumina else, at a temperature of 524aboutWith the pressure of 2.2 MPa, the space velocity of the raw material 1,64-1the ratio of the circulation of the hydrogen-containing gas 1600 m2/m3. Reforming catalysate after selective hydrogenation and stabilization sent to extraction with an aqueous solution of triethylene glycol. After washing the extract from a mixture of triethylene glycol receive 100 kg/h of the product of the following composition, wt. isopentane 0,214; n-pentane 0,386; isohexane 0,822; n-hexane 0,751; isoheptane 0,123; n-heptane 0,023; cyclopentane 0,235; Methylcyclopentane 0,06; methylcyclohexane 0,015; benzene 55,587; toluene 41,244; water 0,540; which is directed to the middle part of the TMA efficiency 25 so t, operating at a pressure of top of 760 mm RT.article and the pressure of the bottom 790 mm RT.article the specific surface of packets TMA-400 m2/m3step shear wave 7 mm, height Z-shaped corrugation 6 mm, the angle of inclination to the vertical 30about. The specified parameters of heat and mass transfer packages provide the differential pressure between the top and bottom of the device 30 mm RT.article Together with the specified product at the point of supply to the machine enter 52,58 kg/h separating agent composition, wt. ativan the e hydrocarbons 20:1. The separation is carried out at a multiplicity of irrigation 10, the temperature at the top of the device 79,2aboutC, the temperature at the bottom 102,4aboutC. On top of the TMA emit a mixture of marginal uglevodorodov and the equilibrium quantity of benzene in the amount of 4,636 kg/h composition, wt. isopentane 4,616; n-pentane 8,326; isohexane 17,731; n-hexane 16,199; isoheptane 2,653; n-heptane 0,496; cyclopentane 5,069; Methylcyclopentane 0,971; methylcyclohexane 0,216; benzene 32,075; water 11,648. The specified stream is sent in raw materials extraction. On the bottom TMA allocate 147,944 kg/h of product containing, by weight. Methylcyclopentane 0,010; methylcyclohexane 0,003; benzene 36,568; toluene 27,878; a separating agent 35,541.

The bottom product of the TMA are separated in a distillation column efficiency 25 so t working with the multiplicity irrigation 3, when the temperature of the top 85,3aboutWith, the bottom 138aboutC.

As a result, the top of the column allocate target product number 54,107 kg/h composition, wt. Methylcyclopentane 0,028; methylcyclohexane 0,009; benzene 99,961; toluene 0,002. The yield of the target product from the potential content in raw materials of 97.3 wt. The product meets the requirements of GOST.

CBM product columns in the amount of 93,837 kg/h composition, wt. benzene 0,015; toluene 43,952; a separating agent 56,033, send in UP>aboutC. Top commodity product emit toluene, at the bottom of a separating agent, which is recycled in the process (food TMA).

P R I m m e R 2 the lower limit of the specific surface of the package TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the specific surface of packets TMA meets the bottom of the claimed boundary, namely 200 m2/m3. As a result, there benzene concentration 99,90% with output from potential 95.6 wt. Target product meets the requirements of GOST.

P R I m e R 3 (upper limit of the specific surface of the package TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the specific surface of packets TMA meets the upper declare the border, namely 600 m3/m2. As a result, there benzene concentration 99,90 wt. with the output from the potential for 95.8 wt. Target product meets the requirements of GOST.

P R I m e R 4 (the lower limit of the pressure drop in the TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the pressure drop in the TMA meets the bottom of the claimed boundary, and the product meets the requirements of GOST.

P R I m e R 5 (upper limit differential pressure TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the pressure drop in the TMA meets the upper declare the border, namely 80 mm RT.article As a result, there benzene concentration 99,90 wt. with the output from the potential to 95.5 wt. Target product meets the requirements of GOST.

P R I m e R 6 the lower limit of the ratio of the separating agent saturated hydrocarbons).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the ratio of a separating agent saturated hydrocarbons meets the bottom of the claimed boundary, namely 3:1. As a result, there benzene concentration 99,90 wt. with the output from potential 95.6 wt. Target product meets the requirements of GOST.

P R I m e R 7 (upper limit of the ratio of the separating agent saturated hydrocarbons).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the ratio of a separating agent saturated hydrocarbons meets the upper declare the border, namely 60:1. As a result, there benzene concentration of 99.98 wt. with vigorelli columns instead TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that the separation is conducted in the TMA, and a distillation column containing 50 single-threaded valve plates operating at temperatures of the top and 86.8aboutWith, the bottom of 120.7aboutWith the expansion of irrigation 20 and the selection of distillate product 7 wt. i.e., the mode is significantly more energy intensive than in example 1. As a result, there target product purity 99,71 wt. with the output potential of 94.9 wt. i.e. a product that does not meet the requirements of GOST.

P R I m e R 9 (comparative, method prototype).

The benzene fraction of the composition shown in example 1, fall in the middle part of the distillation column continuous efficiency 40 so so Separating agent technical isomeric mixture of dioxane alcohols, enter the fifth plate from the top of the column, and 1 wt.h. raw materials serves 8 wt.h. the separating agent. The process is carried out at reflux 10, the temperature of the top of the column 75aboutAnd bottom 205aboutS. Of the cubic product column extractive distillation column efficiency 20 so t at a multiplicity irrigation of 1.0 and a temperature of the top of the column 81aboutWith selected distillate target about yodsoderzhaschie impurities 0,114, with the output from the potential to 95.5 wt.

Oxygen-containing impurities are products of decomposition of dioxane alcohols (heterocyclic compounds) in the presence of water contained in raw materials, in Cuba extractive distillation column at a temperature of 205aboutC. the resulting product does not meet the requirements of GOST.

P R I m e R 10 (the prototype method using TMA).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, with the difference that, as a separating agent, a mixture of dioxane alcohols in accordance with the method prototype [2] taken in accordance separating agent-raw 8:1. As a result, there target product purity 99,86 wt. containing 0,073% of oxygen-containing impurities, i.e., does not meet the requirements of GOST. The yield of the target product 98,8 wt. from the potential.

P R I m e R 11 (with a different composition of raw materials).

Stable product of the process of hydrodealkylation toluene in benzene composition, wt. isohexane 0,413; n-hexane 0,821; isopentane 0,114; n-heptane 0,018; cyclopentane 0,287; Methylcyclopentane 0,092; methylcyclohexane 0,013; benzene 36,12; toluene 61,748; water 0,371, is subjected to separation as in example 1. In the result section GOST.

P R I m e R 12 (another part of the separating agent).

Raw material composition, carried out in example 1 is subjected to separation as in example 1, with the difference that, as a separating agent use individual aromatic hydrocarbon WITH8ethylbenzene. The division allocate target product purity of 99.96 wt. with the output from potential 97,0 wt. The product meets the requirements of GOST.

P R I m e p 13 (without the use of a separating agent).

Raw materials of the composition shown in example 1, is subjected to separation as in example 1, but without the use of a separating agent. The division allocate target product purity 99,81 wt. with the output from potential 95,7 wt. The selected product does not meet the requirements of GOST.

1. METHOD of extraction of BENZENE FROM VYSOKOORIENTIROVANNOGO RAW materials containing benzene, toluene, admixture of saturated hydrocarbons with separation of impurities saturated hydrocarbons in the first stage by rectification with separating agent and the target allocation of benzene from the bottom product of the first stage of the top product of the second distillation column, characterized in that the first stage is carried out in heat and mass transfer devices, the heat and mass transfer packages collected from specially shaped grid in the form of Z-shaped bumps with transverse waves and with a specific surface area of the package 200 to 600 mg/m3, the step of transverse waves, the height of the Z-shaped bumps and angles them to the vertical, providing a pressure differential between the top and bottom of the apparatus in the range of 10 to 80 mm RT.article and as a separating agent used aromatic hydrocarbons WITH8- C9mass ratio of a separating agent saturated hydrocarbons (3 60) 1.

2. The method according to p. 1, characterized in that the aromatic hydrocarbon WITH8use ethylbenzene, ortho-, meta - or paraxylene, or their mixtures, and aromatic hydrocarbon WITH9-propylbenzoyl, isomeric trimethylbenzene, methylethylbenzene or their mixture.

 

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