SU858861A1 - Method of drying solvents - Google Patents

Description

(54) METHOD FOR DRYING SOLVENTS

one

The invention relates to a method of drying ketones, alcohols and other similar solvents and can be used in the petrochemical, oil refining and other industries in which such solvents are developed or used.

A known method of drying alcohols and ketones, according to which a wet solvent is mixed with an extractant (liquid alkyl substituted benzene) having a boiling point at least 40 ° C above the boiling point of the solvent to be dried, in an amount sufficient for phase separation of the mixture (0.5-3 vol. of extractant for 1 part of wet solvent), in which the lower (aqueous) phase contains the main amount of water with a small content of solvent, and the upper (extract) phase - the extractant and the main amount of solvent with no Olsha water content. After settling and separation, the extract phase is subjected to distillation distillation and rectification, while the distillation column is dried, the azeotropic mixture is separated in the azeotropic mixture and a part of the dried solvent with water is recycled for mixing with the extractant; the residue from the distillation distillation is subjected to rectification for the purpose of obtaining in the form of a distillate of a dried solvent; 5, an extractant, which is recycled to the mixture, with a wet solvent is removed from the bottom of the distillation column. Regeneration of the solvent from the aqueous phase is carried out in one distillation stage, at fQ this, an azeotropic mixture of the solvent and water is obtained as a distillate, which is sent for mixing with the extractant, and as a residue, the solvent is free of water, which is removed from the system .

Recommended as extractant

15 use of benzene derivatives, containing 1-4 carbon atoms in the side chains, in particular the use of isopropyl benzene and diethylene benzene.

Significant disadvantage of the known

20 of the method is that it provides for the treatment with the extractant of the entire amount of the wet solvent, which necessitates the circulation of large amounts of the extractant and high energy costs. In addition, expensive substances, such as isopropyl benzene, costing 1 ton in which is 175 rubles, or other benzene derivatives, are used as extractants. Due to the relatively high vapor pressure of these substances when using a known method, it is necessary to use a clear distillation to separate the solvent and extractant, which also increases the cost of the process. Another disadvantage of this method is the need for a long cycle of sludge extractant mixture with a wet solvent, as shown by experimental testing, sludge must be carried out for 3-4 hours. The need for such a long sludge does not allow for the continuity of this stage of the process makes it difficult to automate .

The purpose of the invention is to develop such a method of drying the solvents, which would allow the use of a baking extractant, to reduce the amount of circulating extractant, to reduce the duration of extraction sludge, simplify the technology and increase the depth of the drying of the solvent, reduce energy costs and improve the technical and economic indicators of the process.

The goal is achieved by the fact that the solvent is preliminarily distilled to form a dried solvent containing 0.05-0.5% water and an azeotropic solvent mixture with water, part of which is directed to refluxing the solvent, and part is subjected to extraction with an extractant obtained by regenerating the solvent from the extract phase, and the azeotropic mixture obtained during the regeneration of the solvent from the aqueous phase, while the oil fractions or their products are used as the extractant.

The drawing is a flow chart of the method of drying the solvent.

The wet solvent (stream A) is fed to the drying column 1; Flow B, a wet solvent recovered from the extract phase in column 2, is dispensed here to distill off the solvent from the extractant. Heat is supplied to the drying column 1 by means of a closed steam in a boiler 3. The dried solvent from the bottom of the drying column 1 is removed from the system through the cooler 4. The azeotropic mixture of solvent and water (stream B) from the top of the drying column 1 after condensation and cooling in condenser condenser 5 partially goes to the top plate of the drying column as irrigation, and the rest in vapor phase or condensed state goes to mixer 6. Recycling extractant (stream G) from column 2 for the distillation of the solvent from the extractant and an azeotropic mixture of solvent and water from the column 7 for the distillation of the solvent from water. After intensive contact in the mixer b, the mixture of these products enters the decanter 8, in which, as a result, the mixture is separated for 5-30 seconds into the extract phase (upper layer), which is the solvent saturated extractant, and the aqueous phase (lower layer), representing a solution of the solvent in water. After settling in the decanter 8, the extract phase (stream D) is fed to column 2, heat is supplied to the boiler in boiler 9 by means of closed steam. Recycled extractant, partially or completely freed from solvent

(stream D), from the bottom of column 2, after cooling in refrigerator 10, the solvent from the top of column 2 containing water impurity (stream B) after condensation and cooling in condenser-cooler 11 is partially fed to column 2 as reflux, and the remainder is sent to the substantial column 1 along with the main stream of wet solvent.

d. The aqueous phase from the decanter 8 (stream L) is fed to the column 7 for the distillation of the solvent from water, working with the introduction of water vapor (stream 3). The azeotropic mixture of solvent and water from the top of the column 7 (stream I) is sent to the condenser cooler 12

5 and further partially for irrigation of coloium 7, and the rest to mixer 6 for mixing with the extractant. The water freed from the impurity solvent from the column 7 (flow K) is removed from the system.

Example 1. Take 1000 g of MEK containing 4.5 wt. % water, and subjected to azeotropic drying. As a result of this, 602 g of solvent are obtained with a water content of 0.2% and 398 g of an azeotropic mixture of solvent with water containing

5 1 1% WATER.

The resulting azeotropic mixture is mixed with the extractant - crap FR. 340- 470 ° C t. Pl. 48.2 ° С, oil content 22.4%, density at 20 ° С, 0.827, viscosity at 100 ° С, 3.51, and refractive index at 70 ° С, 1.440.

The solvent was extracted from the azeotropic mixture at 60 ° C and the azeotropic mixture was processed with an extraheite of 1.2; 2.5; 5.0 and 10.0. Separation of the extraction products is carried out by suction for 15 seconds.

Example 2. Take 1000 g of IEC containing 3.8 weight. % water and subjected to azeotropic drying. As a result of this, 662 g of dried solvent are obtained with a water content of 0.12% and 338 g of an azeotropic mixture of solvent and water containing 11 / o water.

The azeotropic mixture obtained is mixed with the extractant — paraffin distillate fr. 320-420 ° С of Manglyshlak oil with a density of 0.8207 at 70 ° С, so pl. 29.8 ° C; viscosity 5.59 at 70 ° C; and a refractive index of 1.4555 at 70 ° C.

The solvent was extracted from the azeotropic mixture at 30 ° C and the azeotropic mixture was treated with an extractant of 0.8; 1.2; 2.0 and 4.0. Separation of the extraction products is carried out by sifting for 20 seconds.

Example 3. 1000 g of MEK containing 3.8% of water are taken and subjected to azeotropic drying, as described in Example 2. The azeotropic mixture obtained is mixed with the extractant — paraffin distillate fr. 320420 ° С of mangyshlak oil; extraction was carried out at 45 ° C and the azeotropic mixture was treated with an extractant 1.0; 2.5; 4.0 and 6.0. Separation of the extraction products is carried out by sifting for 20 seconds.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION A method of drying solvents of the class of ketones and alcohols, which are limitedly miscible with water to form azeotropic mixtures with a minimum temperature of puncture, including extraction of the solvent from its mixture with water using a hydrocarbon extractant, separation of the extraction products into the aqueous and extract phases by distillation and subsequent recovery of the solvent from separated phases, characterized in that, in order to reduce the amount of the extractant, reduce the sludge time and increase the drying depth, is preliminarily subjected to distillation to form a dried solvent containing 0.05-0.5% water and an azeotropic solvent / water mixture, part of which is directed to refluxing the solvent, and part is subjected to extraction with an extractant obtained by regenerating the solvent from the extract phase, and azeotropic the mixture obtained during the regeneration of the solvent from the aqueous phase, while the oil fractions or their products are used as the extractant. Sources of information taken into account during the examination 1. US Patent No. 2582214, cl. 202-60, 1952 (prototype).