SU880436A1 - Method and apparatus for separating mixtures - Google Patents

Description

The invention relates to the separation of mixtures by distillation and can be used in the refining, petrochemical, chemical and other industries. A known method of separation of mixtures by distillation with heat removal at the top of the column using cold evaporation, in which the Ficata’s reagent pairs condensed and cooled to the temperature of cold irrigation, is partially fed to the column reflux, and the remaining part is directed to the next column, preheating in an additional heater to the feed temperature to the next stage of rectification, since the feed temperature to the column is always higher than the cold spray temperature 1. However, this is necessary before The energy consumption for heating the rectification is complete, and the heat of condensation of the rectified vapor is not used because of its low temperature level. The closest to the proposed result achieved is a method of separation of mixtures by distillation with heat removal at the top of the column using hot irrigation. This method is proposed to be used in the separation of mixtures of hydrocarbons (in particular the propane-butane fraction) into separate components. In this case, the debutanizer rectified condensed in the condenser is partially fed to the debutanizer irrigation, and the rest of the rectified at boiling point is sent to the depropanizer 2. The debutanizer, the condenser, the pump and the second stage, the depropanizer, install in the installation / containing column. With this method of additional costs for heating the depropanizer feedstock is not required, however, due to an increase in irrigation temperature, its quantity increases significantly, and consequently the costs for condensation of rectified vapor increase, the diameter of the first stage increases due to the increase in its load on the liquid and in pairs. pressure in the column increases, which can lead to a decrease in the clarity of the rectification.

The purpose of the invention is to reduce the rectification rate due to heat recovery of rectified vapors.

This goal is achieved by the fact that in the method of separation of the mixtures, which involves removing the vapor from the top of the first stage distillation column, condensing these vapors and feeding the condensed vapors to the first stage distillation column and. the second stage part of the vapor removed from the top of the first stage distillation column is mixed with part of the condensed vapors ..

The device allowing to carry out the method is equipped with a flow divider installed at the vapor outlet from the first stage distillation column and a mixing condenser located between the stream divider and the second stage distillation column.

The drawing shows a device for implementing the method.

The device contains rectification columns of the first stage 1 and the second stage 2, the flow divider 3, the condenser 4, the refrigerator 5, the pump 6 and the mixing condenser 7.

The method is carried out as follows.

Couples are withdrawn from the top of the first stage distillation column 1. Some of these vapors are condensed in condenser 4 and cooled to a cold irrigation temperature in refrigerator 5. Condensed vapors are pumped to pump the first fraction 1 distillation column reflux and the second stage 2 distillation column through a mixing condenser 7. Part the upper part of the first stage distillation column 1 is fed into the second stage distillation column 2 with part of the condensed vapors in the mixing condenser 7. As a result, Coming out of the mixing condenser 7, with the required degree of heating due to the heat of condensation of the rectified vapors of the column, and directing it to the second stage distillation column 2.

The ratio of steam and liquid hoTOKOB rectified, sent to the mixing condenser, is determined from the heat balance

, D,

- consumption received

F mixture (raw material of the second distillation column), kg / h;

  respectively, the consumption of steam and liquid streams entering the mixing condenser, kg / H;

5, the heat content of the resulting mixture, vapor and liquid flows, respectively, kcal / kg.

Q From the material balance of the mixing capacitor

F D, + Dg

Therefore, the ratio of vapor and liquid flows, -directed 5 to the mixing condenser, is determined from the equation

OL. tp - tp. Oh, 4. - t.

Example 1. A mixture consisting of 8.4% ethylbenzene, 16.2% i-xylene, 35.3% n-xylene, 40.1% o-xylene is fed to a first-stage distillation column. From the upper part of the first stage distillation column, 21,556 kg / h of vapors containing 12.6% of ethyl benzene, 24.4% of i-xylene, 53.0% of W-xylene, and 10.0% of o-xylene, are discharged at. Some of these vapors in the amount of 20192 kg / h condense and

185540 kg / h fed to the irrigation of the first stage distillation column at. Part of the vapor of 1364 kg / h is mixed with 1652 kg / h of condensed vapors, which provides the required feed temperature to the second stage distillation column 170C.

Example 2. Stable gasoline

l is separated in a first stage distillation column. From its upper part, vapors of the NK-105S fraction are withdrawn at SW. Part of these vapors 204320 kg / h are condensed, and of these, 104000 kg / h are fed for distillation irrigation.

5 columns of the first stage at 40 ° C. Another part of the vapors is mixed with 100,320 kg / h of condensed vapors in a ratio of 1: 4, which ensures the required flow temperature in the second stage distillation column 88 s.

In the examples provided, savings are achieved by reducing 5 the number of condensed vapors that need to be pumped by the pump, and reducing the cost of energy for condensation of the first stage distillation column vapors and heating.

raw material of the second stage distillation column.

The economic effect of using the proposed method averages 6-15% of the variable part of the reduced costs.

Claims (2)

Claim 1. The method of separation of mixtures, including the removal of vapors from the upper part of the distillation column of the first stage, the condensation of these vapors and the supply of condensed vapors for irrigation of the distillation column of the first stage and into the distillation column of the second stage, so that in order to reduce the cost of rectification due to heat recovery of the vapor of the rectification, before being fed into the distillation column of the second stage, part of the allocated vapors from the upper part of the distillation column of the first stage is mixed with a part of the condensation vapors. 2. A device for implementing the method according to π. 1, comprising distillation columns of the first and second stages, a refrigerator, a condenser and a pump, characterized in that it is equipped with a flow divider installed at the vapor outlet of the distillation column of the first stage and a mixing condenser located between the flow divider and the distillation column of the second stage. to