PAKHT Exchange Rate Project - Rectification

Description of the process diagram of the fractionation plant

Developed rectification plant - continuous operation.

The initial mixture is supplied from the warehouse to tank E1. A level measuring device is installed on the vessel, which indicates and signals the upper limit and its lower limit. Upon reaching the upper mark, supply of the initial mixture to the container is stopped, upon reaching the lower mark, it is resumed.

Liquid mixture is pumped from vessel E1 by centrifugal pump H1. The pump is duplicated in case of failure by the spare pump H2. There is also a bypass line operating in the event of a shutdown of the plant for repair or prevention, which serves to lower liquid from the pipeline.

The plant provides for rational use of heat. The heat of the effluent streams is used to heat the effluent streams, that is, the initial mixture is heated by the heat of the liquid removed from the bottom of the column, the so-called bottom residue. This heat exchange is carried out in recuperator X1. This is a heat exchange shell-and-tube apparatus, in one space of which the initial mixture is pumped, and in the other - bottoms.

After leaving the recuperator, the starting mixture is heated, but not to boiling point. Further heating of mixture is carried out in preheater P. Heated initial mixture is supplied to pipe space of this shell-and-tube heat exchanger, and heating steam supplied from boiler room is supplied to pipe-and-tube space. The steam, condensing, gives its heat to the initial mixture, heating it to the boiling point.

The temperature of the initial mixture is controlled by a special device.

The boiling mixture then enters the distillation column.

In the column, the vapors of the initial mixture go up, enriched with benzene, and the liquid phase goes to reflux the lower part.

The liquid discharged from the bottom of the column is partially withdrawn to the tank E2, passing through the recuperator X1 (see above), and partially supplied to the reboiler K, which heats the residue to boiling point and completely evaporates it. After leaving the reboiler, the bottom residue completely changes into steam. Heating is performed by heating steam coming from boiler house .

Condensed vapors of heating steam from preheater and reboiler are removed by means of condensate traps KO2 and KO1, respectively. In order to ensure continuous operation of the plant during repair and inspection of the water drains, they are equipped with a bypass (bypass) line .

Steam from the reboiler rises up the column, connects to the vapors of the initial mixture, and, increasingly enriched with benzene, exits through the upper nozzle. It is then sent for condensation to reflux generator D.

In the reflux condenser, benzene vapors condense due to cooling water.

Condensate is supplied to E4 tank. Here it is divided into two streams: liquid taken for reflux of the column - reflux and finished product - distillate. Reflux is pumped into the column by pump H7, which is duplicated by pump H8. A bypass (bypass) line is provided for liquid lowering during plant shutdown.

The reflux fed to the reflux column is mixed with the feed mixture and flows down the trays into the column cube.

Distillate flowing through the pipeline is supplied to the cooler X2, where it is cooled to the desired temperature with cold water. The cooled distillate enters vessel E3. There is also installed a level measuring device, which includes a pump H6 when the amount of the finished product - benzene - reaches a given mark.

The circulating water flows through line 1 and is removed after performing the specified functions through line 10 .

Heating steam is supplied via line 2 and removed as condensate via line 3.

When the rectification plant is stopped for repair or prevention, the remaining liquid is lowered from the pipes, opening bypass lines into the tanks, and from them the liquid is drained into the sewer 5.