SU1616889A1 - Method of separating methylethylketone - cyclohexanon - water mixture - Google Patents

Abstract

The invention relates to lower ketones, in particular the separation of a mixture of methyl ethyl ketone-cyclohexanone and water, which can be used in chemical technology. The goal is to reduce energy costs. For this, the separation of this mixture is carried out in three distillation columns with separation from the bottom of the 1st column of the main amount of water and separation of the distillate. The latter is stratified in the Florentine vessel into organic and aqueous layers (water is returned to the 1st column). The organic layer is used as feed for the 2nd column, and the extractant-cyclohexanone is fed from the top with a selection into the methyl ethyl ketone distillate, cyclohexanone and water (the anhydrous mixture of methyl ethyl ketone and cyclohexanone remains in the bottom). As a feed, in the 3rd column operating at atmospheric pressure, the bottom product of the 2nd column is used to obtain pure methyl ethyl ketone and pure cyclohexanone (cube). Here, a portion of the cyclohexanone in the form of a recycle stream is used to reflux the column 2 with a mass ratio of feed to reflux of 5.56-7.31. In this case, the 2nd column distillate is sent for separation into a Florentine vessel. In this case, the need to evaporate the circulating cyclohexanone stream is eliminated. 1 dw., 5 tab.

Description

The invention relates to chemical technology, in particular to a method for the purification of organic solvents using azeotropic distillation.

The aim of the invention is to reduce energy costs in the allocation of methyl ethyl ketone and cyclohexanone from their mixture JB in the presence of water.

But the drawing shows the principal technological scheme of the sporob.

The technological scheme includes distillation columns 1,2 and 3 and the Florentine vessel 4. Source stream 5 containing methyl ethyl ketone, il-hexane and water is fed to the Florentine vessel 4. The lower (water) layer 6 from the Florentine vessel is fed to column 1, where the separation of solvents from the main mass of water discharged from the bottom stream 7.

00 00

with

The leaflet stream 8 is directed to the Florentine vessel, from which the organic layer 9 is fed to column 2, irrigated from above with an extractant, which is cyclohexanoic and from the bottom of column 3. 3 results in distillate 10 column 2 containing methyl ethyl ketone, cyclohexanone and water, in the bottom stream 1; an anhydrous mixture of methyl ethyl ketone and cyclohexanone remains. Stream 12 is formed from a mixture of streams 5, 8 and 10. The bottoms stream 11 is sent for separation into column 3, where it is subjected to separation into pure methyl ethyl ketone (stream 13) and cyclohexanone (stream 14). The part of cyclohexanone, which is discharged from the cube of column 3, is used as a recirculated stream 15 for irrigation of the column 2, and the remaining part is diverted from the system as the desired product.

Example 1. The initial mixture in the amount of 100 kg / h composition, May,%: methyl ethyl ketocyclohec: Sanon 16.7; water 50.00 - served in the Llorentinian jar, where delamination occurs at 60 ° C. Water (Lazu from (Olorentinian vessel is fed to the rectification in the first column with efficiency K), tt, on the first plate oiepxy in the amount of 68.85 kg / h; composition, wt.%: Methyl ethyl ketone 10.04; cyclohexapone 3.67; water 86.29. At the top of the column, 96.1 s, distillates are taken away, kg / h: metts-1lcrton 6.91; diclohexan-one 2.53; water 9.41 - which is sent to the Florentine vessel. In Kyfie, the columns emit water in an amount of 50.00 kg. The organic phase from the Florentine vessel 3 is 92., 96 kg / h composition, wt.%: Methyl ethanol ketone 46.60; peak-letexapop 34.39; water G :, 97 - served for rectification into the second column with a yield of 24 tons, on the 10th plate from the top at zero reflux. 15 the same column on the plate above serves cyclohexanone with in the amount of 516.35 kg. in relation to the power of the column 5556 :, at the top temperature columns 82.84 ° C take distillate in an amount, kg / h: methyl ethyl ketone 13.34; cyclohexanone 17.65; water 11.97. From the bottom of the column, take the mixture in a quantity, kg / h: methyl keel 33.26; cyclohexanone 533.09, - serves it for separation

in the third column with an efficiency of 10 tons, on the sixth plate from the top. At the temperature of the top of the column

79.4 ° C; reflux number 2: take distillate in an amount, kg / h: methyl ethyl ketone 33.26; water 0.07. Pure cyclohexanone (533.02 kg) is taken from the cube of the column. 5 of which are

(516.35 kg / h), return the second column for irrigation.

Examples 2 and 3. The hardware and process conditions are similar to those described in

Example l.-B of Table 1 shows the effect of the separation agent cyclohexanone consumption on the composition of the bottom product of column 2, where the process of extractive rectification is carried out.

As can be seen from the table. (examples 2-3) j only within the required limits of the ratio of the separating agent - cyclohexanone and the initial stream of raw materials, the necessary clarity of separation is achieved. So in example 2, when the ratio of cyclohexanone and raw materials is 3.80: water appears in a cube of an extractive distillation column in a concentration of 0.14 oil mass, which negates |

affects the quality of methyl ethyl ketone produced in column 3. Therefore, the water content in the bottom product of column 2 should not exceed 0.01 wt.%, so that the water concentration

in the commodity methyl ethyl ketone, it did not exceed 0% by weight, which is dictated by technological standards.

P p:,: i e p s 4-7. The composition of the initial mixture, the efficiency of

lonny., the amount taken

distillate, 1 shegm number and consumption of cyclohexanes separating agent such as, as in example 1. B Table 2 shows the effect of; , g: oceans and plates in the rectification column 2 for the results of separation of the initial mixture.

The separation task is achieved when the initial one is fed to the 10–12th plate; since only in this case the water content in the bottom liquid is less than 0.01% wt.%. Changing the position of the food plate in column 2 has almost no effect on

 the amount of energy costs in this column.

In a known manner, the mixture of methyl ethyl ketone-niclohexanone-bov-yes is poured into column 1, where it is separated

from its main body of water. The distillate columns are sent to the Llorantian vessel for delamination. The syllable of the Florentine vessel is returned to column 1, and the organic comes into further separation into the system of columns 2 and 3. Column 2 works with methyl ethyl ketone irrigation from the bottom of column 3 with reflux number 5. In column 2 of the cyclo- hexanone azeotrope - methyl ethyl ketone - water is distilled off (water content is 11.3 wt,%) fed to column 3, operating under a pressure of 5-7 kg / cm. As the pressure increases, the azeotropic point shifts toward a higher water content than distillation at atmospheric pressure, thereby distilling methyl ethyl ketone – water with a water content of 19% by weight into the distillate, and in the bottom of the column 3 dried methyl ethyl ketone is taken. The distillate is fed to the second Florentine vessel, the aqueous layer from the Florentine vessel is returned to the power supply of column 1, and the organic layer is fed to the power supply of column 3.

The results of the comparison of energy costs in technological separation schemes for the method known and proposed are given in Table 3.

In tab. Figures 4 and 5 present the data for calculating the material and heat balances of the separation of the methyl ethyl ketone – cyclohexanone – water mixture according to the proposed and known methods, respectively.

Thus, separation of the mixture in the presence of an azeotropic agent such as cyclohexanone allows in the 2nd column the separation of water from methylstilketone and cyclohexananone, while according to a known method, with conventional rectification, the water goes along with methyl ethyl ketone, which complicates the further separation of the mixture, since for the separation of the azeotrope - methyl ethyl ketone - water, a pressure column is required.

168896

In the implementation of the proposed method, cyclohexanone fed to the separation is mainly removed from the bottom of the column 2 with methyl ethyl ketone and only a small part of it is discharged from the distillate mixed with methyl ethyl ketone and water. Further separation of cyclohexanone and methylethyl 10

the ketone is carried out by simple distillation in the 3rd column. Application

The proposed method allows juice-, flow rates, selected from the 2nd

3rd columns, in addition, eliminates j with the need to evaporate the flow

circulating cyclohexanone, which 1 results in a reduction in

energy costs of separation

compared with the known method: 20% heat saving is 21%, and

save in the cold - 60%.

Claims (1)

Invention Formula 25 A method of separating a mixture of methyl ethyl ketone - cyclohexanone - water in three distillation columns with separation of the main amount of water from the bottom of the first column, stratifying 30 distillates of the first column in a Florentine vessel into organic and aqueous layers with returning the aqueous layer to the first column, using the organic layer as feeding the second column, distilling off the mixture containing methyl ethyl ketone and water in the form of a distillate of the second column and obtaining a dehydrated cyclohexanone and methyl ethyl ketone, distinguished by In order to reduce energy costs, cyclohexanone from the bottom of the third column is fed to the top of the second column as a reflux at a mass ratio of 5.56 to 7.31: 1 oroshe, and distilled from the top of the second column to the Florentine vessel. and get methyl ethyl ketone with. top and cyclohexanone from the bottom of the third Q column, operating at atmospheric pressure. T a b l and c a Table 3 Note, Heat Capacity (kk / kg. C) of cyclohexanone and methyl ethyl ketone 0.4-0.5, water 1.0. I Table 5 fi l and u a 4