RU18647U1 - RECTIFICATION UNIT UNDER ATMOSPHERIC PRESSURE - Google Patents

Abstract

A device for distillation under atmospheric pressure, containing a distillation column and a separator connected to it by a bottoms withdrawal pipe, mixture supply pipelines to a distillation column and a target product, characterized in that it is equipped with an ejector, the input of which is connected via a vapor phase to the separator, the input by liquid - with the pipeline supplying the mixture to the distillation column, and the output - with the middle part of the rectification column.

Description

MPKV01 DZ / 32

Atmospheric pressure rectification device

The device relates to mass transfer equipment and can be used at enterprises of the chemical, oil refining and petrochemical industries in mass transfer processes, including in the technology of distillation of mixtures, in regenerative systems for the absorption treatment of gas emissions with recirculating absorbent, etc.

In the process of distillation of mixtures under atmospheric pressure in the lower part of the rectification column, excessive pressure occurs, which prevents the extraction of the target component from the mixture. The decrease in pressure in the distillation column (distillation under vacuum) significantly increases the degree of extraction of the target component from the mixture, however, such schemes require expensive equipment, the operation of which is associated with significant energy consumption (Kasatkin L.G. Main processes and apparatuses of chemical technology. M .: Chemistry , 1973, p. 484)

The closest in technical essence and the achieved result to the proposed one is a device for rectification (RF Patent SU No. 1606140 A1 class. 01 D 3/32, publ. 15.11.90). This device in addition to the rectification column is equipped with an additional cube with heating. The remainder of the rectification column is sent to an additional cube. Heating the residue in an additional cube leads to the formation of a vapor phase containing not recovered in the column

distillation of the target compound, which under its own excess pressure returns to the middle part of the distillation column. This increases the reliability of the rectification device and the quality of the target product.

The disadvantage of this device is the need to supply energy to heat an additional cube, which reduces the efficiency of the installation.

The problem solved by the proposed utility model is the improvement of the device for rectification of mixtures under atmospheric pressure with a high degree of extraction of the target component. The technical result from the use of a utility model is to increase efficiency by reducing energy consumption. In addition, the availability and dimensions of additional equipment, which is equipped with the main distillation column, make it easy to upgrade the corresponding installation.

This result is achieved by the fact that the device for distillation under atmospheric pressure, containing a distillation column and a separator connected to it by a bottoms withdrawal pipe, the mixture supply pipelines to the distillation column and the target product are equipped with an ejector, the input of which through the vapor phase is connected to the separator, the input is liquid with a pipeline for supplying the mixture to the distillation column, and an outlet with the middle part of the rectification column.

In FIG. 1 shows a schematic flow diagram of the proposed device for rectification.

The device contains a distillation column 1, the bottom part of which is connected by a pipeline 2 to the separator 3. The ejector 4 is installed on the pipeline 5 for supplying the mixture to the rectification column 1 and connected via the vapor phase to the pipeline 6

with a separator 3. The device is equipped with a pipe 7 for the yield of the target product, a pipe 8 for the removal of bottoms from the separator 3 and a heat exchanger 9 for heating the mixture before it is fed to the distillation column.

The device operates as follows:

The bottom residue, containing the unreduced target component, from the rectification column 1 by gravity pipe 2 flows to a separator 3 in which at a temperature close to the temperature of the rectification column 1 and due to the pressure drop (relative to the pressure in the rectification column 1), partial evaporation of the mixture together with the remainder of the target component. From the separator 3, the bottom residue depleted in the target component is discharged via pipeline 8. The degree of pressure drop in the separator 3 is determined by the efficiency of the ejector 4, which in addition to this function ensures the return of the vapor phase formed in the separator 3 to the rectification column 1 together with the mixture supplied via pipeline 5 through the heat exchanger 9.

Thus, the mixture entering the distillation column 1 has an increased concentration of the target component (in comparison with the initial one before it enters the ejector 4), which improves the quality of the separation of the mixture and increases the yield of the target component into the pipeline 7. The bottom residue at the outlet of the separator 3 has a smaller the content of the target component in comparison with its concentration in the residue at the outlet of the cube of the rectification column 1. In some cases, the factor of additional extraction of the target component in the separator 3 allows to reduce the temperature the cube of the rectification column 1 while maintaining a given value of the degree of extraction.

The efficiency of the proposed device depends on the efficiency of the ejector 4, which, in turn, is determined by the energy of the mixture flow entering its inlet through the pipeline 5. Using the proposed device becomes economically feasible if it is possible to reduce the pressure in

separator 3 by a value of 0.2 - 0.3 atm or more with respect to the pressure in the rectification column 1.

For practical use of the proposed device, it is possible to recommend options involving the condensation of the vapor phase extracted from the separator 3 with further forced supply of liquid to the rectification column 1. In addition, in some cases (for installations of oil refining industry enterprises, for example), it is advisable to supply extracted from the separator 3 vapor phase directly into the pipeline 7.

An example of the operation of the device:

1. Using the proposed device as a part of a rectification column of an absorption unit for the recovery of gas emissions of ethyl chloride with a recirculating absorbent allows you to save the required degree of extraction of ethyl chloride from the absorbent while lowering the temperature of the cube of the rectification column from 220 ° C to leo C. At the same time, the ejector does not create a vacuum in a separator, the pressure of which is maintained at atmospheric level. The pressure of the bottom of the rectification column is 1.4 at.

2. To increase the output of gasoline fractions from the topping column of the ABT installation, the use of the proposed device allows to increase the degree of their distillation from oil by 5-6%. No additional energy is required.

Thus, the proposed device can improve the efficiency of distillation units under atmospheric pressure by reducing energy consumption.

the degree of extraction of the target component to significantly reduce energy consumption for heating the mixture in the column.

Compared with the prototype, the proposed device is more economical, since additional extraction of the target component from the residue does not require subsequent heating.

Claims (1)

A device for distillation under atmospheric pressure, containing a distillation column and a separator connected to it by a bottoms withdrawal pipe, mixture supply pipelines to a distillation column and a target product output, characterized in that it is equipped with an ejector, the input of which is connected via a vapor phase to the separator, the input by liquid - with the pipeline supplying the mixture to the distillation column, and the output - with the middle part of the rectification column.