SU1567603A1 - Method of solvent dewatering - Google Patents

Abstract

The invention relates to refining, in particular the dehydration of solvents in dewaxing and deoiling of petroleum fractions. The purpose of the invention is to reduce energozatzat and intensify the process. The latter is carried out by supplying solvent vapors containing methyl ethyl ketone or its mixture with methyl isobutyl ketone and water to a distillation column. From its bottom, a dried solvent is removed, and from the top, azeotrope vapors with diisopropyl ether, solvent and water, which are cooled, condensed and decanted into aqueous and organic layers. The latter is used as reflux of the column, and the aqueous layer is directed to stripping traces of solvent in the ketone column. In addition, diisopropyl ether is added to the decanter. These conditions reduce the frequency of solvent circulation in the dewatering system [up to 10-15%], while achieving a similar, known degree of drying the solvent [up to 0.3%]. 1 il. 4 tab.

Description

The invention relates to methods for dehydrating solvents in dewaxing and de-oiling paraffin-containing raw materials with selective solvents and can be used in the refining industry.

The invention extends to a group of selective solvents containing methyl ethyl ketone (MZK) or a mixture of methyl ethyl ketone and methyl isobutyl ketone (MIBK). Moreover, benzene, toluene, and other J may be present in the solvent composition.

components that increase the solubility of oils in selective solvents.

The aim of the invention is to intensify the process of dehydration of the solvent used in dewaxing and freeing oil fractions, reducing energy consumption for operating the solvent regeneration system due to the increased amount of circulating body races in the dehydration system, instantly the flow rate of circulating water of N-1. Wiping and cooling the vapor p to i F Miii, provided the condition of D. i-, n, -saw MI- ..0 | a mixture

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soo o so

solvent and water in the dewatering system, as well as dehydration of wet methyl ethyl ketone.

The drawing shows a principle, a schematic diagram explaining the method.

The regeneration system receives wet vapors of the solvent components via line 1 to distillation column 2. Water vapors in the form of aqueous azeot-J ropa diisopropyl ether (DIPE) 3 are removed from the top of column 2, condensed, cooled and fed to the decanter separation unit k.

In addition, condensed and cooled ketone and water vapors from line 5 from ketone column 6 and water vapor with the highest boiling solvent components via line 7 from the recovery system columns are sent to decanter k. A dehydrating agent 8 DIPE, which weakly dissolves water, is preliminarily introduced into decanter C, which then circulates in the dewatering system. For a total of 2 losses of ether occurring during the operation of the dehydration system, fresh DIPE is periodically supplied to decanter k.

DIPE does not form azeotropes with solvent components, and DIPE azeotrope - water has the lowest boiling point among possible water azeotropes for the considered solvent components. This conclusion comes from the data given in Table. 1. In addition, the solubility of water in a condensed and cooled DIPE azeotrope — water itself is low among the possible azeotropic compositions.4

In the decanter, a mixture of all liquid streams separates into a layer enriched in solvent and a layer enriched in water. The solvent enriched layer consists mainly of d diisopropyl ether mixed with the components of the selective solvent supplied via lines 5 and 7. The presence of a large amount of DIPE in the layer significantly reduces the solubility of water in C. A solvent enriched layer through line 9 through a semi-deaf partition flows into another section of the decanter and is applied for irrigation / columns 2. The dried solvent along line 11 is removed from the lower suit of the colony 2. Water enriched with a line 10 from decanter 4 is fed into The ketone column 6, where traces of the solvent are stripped from water with live steam 12. Water that does not contain solvent 13 impurities is removed from column 6. Thus, diisopropyl ether circulating in the dewatering system plays the role of a dehydrating agent. cient wet paoov solvent components.

The method was tested on a continuous laboratory distillation column equipped with twelve cap trays and having a maximum raw material throughput of 300 g / h. Raw materials-solvents of a given composition, served on the seventh plate, counting from above.

The aqueous azeotrope is removed from the top of the column, condensed, cooled to 50 ° C, and divided into two layers. The solvent-rich top layer is fed to the upper plate of the laboratory column as a reflux. The amount and composition of irrigation are modeled by the operation of the ketone column and the stripping columns of the solvent recovery system.

The dried solvent is removed from the bottom of the laboratory column.

Thus, with the help of a laboratory column, the process of solvent dehydration of the following composition is simulated, OBD: IEC – MIBK 70:30; IEC - toluene 75:25; pure IEC. In this case, it was taken into account that the solvent is usually regenerated from a solution of paraffin: - or gacha is carried out in two stages, with the second stage being a stripping column. Regeneration of the solvent from the filtrate solution is carried out in two or more steps and the last, and the latter is stripped off. The following are examples of solvent dehydration in accordance with known and proposed methods. The amount of solvent vapors supplied to the laboratory column was determined on the basis of experimental data on the deoiling (dewaxing) of wet samples of the raw material and the subsequent distillation of the solvent from precipitates of the solid phase. The proportion of the distillate solvent from the precipitates in the first stage of the distillate was 85-90 wt.%.

The amount of reflux is calculated based on the required degree of solvent dehydration and the data on the water content in the decantation traders for the mixture of solvents and water in the decanter.

The efficiency of the solvent dewatering process is estimated by the K coefficient, which is the ratio of the irrigation flow per unit mass of the dried solvent.

Example 1. During the regeneration of the solvent from the precipitate of paraffin, obtained from g of wet gachi fraction 3 0-A60 ° C in the solution IEC: MIBK 70: 30, received 279.6 g of solvent vapor and water. Couples are served in a laboratory column. Irrigation is applied to the top of the column — a layer from the decanter, which consists mainly of methyl ethyl ketone (a known method) or di-isopropyl ether (DIPE) (the proposed method) with an admixture of more kokipyushchy components of the solvent and water. From the top of the laboratory column, rectified vapors are taken, representing the aqueous azeotrope of MEK or DIPE, which is condensed, cooled and sent to a decanter, and impurities of high-boiling components are removed from the bottom of the column together with the dried solvent. The aqueous layer from the decanter is sent to the ketone column.

The material balance and temperature conditions of the IEC - MIBK 70 - 30 solvent dehydration process are given in Table 2 in accordance with known and proposed methods. 2

The coefficient K for a known method is equal to 0.89, for the proposed described 0.76.

PRI mme R 2. When the solvent is regenerated from a precipitate of paraffin obtained from 250 g of wet gachy fraction 330-480 ° C in an MEK-toluene solution of 75:25, 260.5 g of solvent vapor and water are obtained, which are dehydrated in accordance with with the scheme described in example 1.

The material balance and temperature conditions of the dehydration process of the IEC-toluene 75: 25 solvent in accordance with the known and proposed methods are given in Table. 3

The coefficient K for a known method is 0.79, and for the proposed 0.67.

0

five

PRI me R 3. When regenerating a solvent from a precipitate of paraffin obtained from 250 g of wet gachy fraction 350-A20 ° C in an MEK solution, 25.7 g of MEK vapor and water were obtained, which were dehydrated in accordance with the scheme, as described in Example 1. Due to the fact that it is not possible to dehydrate a pair of wet MEK in a known manner, in Table. k shows the material balance and temperature conditions of the dewatering process according to the proposed method.

The coefficient K in this case is equal to 0.83.

From the above examples, it follows that the proposed method compared

with a known method allows significantly (up to 10-15%) to reduce the frequency of solvent circulation in the dewatering system while achieving the same degree of drying of the solvent (to

0.3 wt.%). Furthermore, the method makes it possible to dehydrate a pair of wet MEK that cannot be dried using a known method.

Claims (1)

Invention Formula Dissolve dewaxing process and o6c3Mac.ii.i-. Containing methyl ethyl ketone or its mixture with methyllysobutylketone by supplying ketone-containing solvent vapors and water to a distillation column, from the bottom of which a dried solvent is drawn off and from the top derive azeotrope solvent and water, cooling them, condensation and feeding into the decanter, followed by feeding the resulting organic layer as reflux of the distillation column and feeding the aqueous layer to stripping traces of the solvent in th A new column, characterized in that, in order to intensify the process and reduce energy consumption, diisopropyl ether is additionally introduced into the Decanter with a selection of water vapor from the top of the distillation column as an azeotrope with diisopropyl ether. Table 1 Known method Distillation column Couples wet IEC - MIBK Irrigation (IEC - MIBK) Dried IEC - MIBK Rectified Decanter Water vapor and IEC - MIBK Recipe from ketone column Distillate from distillation column Solvent layer Aqueous layer Ketone column The aqueous layer in the column Steam Water from the bottom of the column Hp Distillation column Couples wet IEC - MIBK Irrigation (DIPE - IEC - MIBK Dried IEC - MIBK Rectified Decanter Water vapor and IEC - MIBK Recipe from ketone column Distillate from distillation columns table 2 After condensation and cooling. Known method Vapor Wet MEC - Toluene Irrigation (MEC Luol) Drained IEC Rectificate The proposed method Couples of wet IEC Couples of wet IEC98248,85,92,32 Irrigation (DIPE - IEC) 50244,04,21,69 Drained IEC82297,60,90,30 Rectified63195,29,24,48 Table 3 ten 50 85 75 256.3 4.2 1.61 250.2 332.1 174.4 12.0 1.0 15.2 4.58 0.30 8.03 Table 4 W Editor M. Nedoluzhenko Compiled by L. Ivanova Tehred M.HOdanich Proofreader L. Patay Order 1301 Circulation 39 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab., K / b at five -four g 12 Subscription