SU757171A1 - Rectification-processes automatic control method - Google Patents

Description

The invention relates to control systems of mass transfer processes in oil and gas processing, petrochemical, food and other sectors of the economy.

The known method of automatic control of the distillation column by adjusting the flow rate of irrigation of the column according to the temperature difference in the upper section of the column [1].

The disadvantage of this method is the impossibility of obtaining the target product of high quality with different composition of raw materials.

This is due to the fact that with temperature stabilization on the control plates, due to the lack of correction of the difference in these temperatures, the quality of the target product changes in the composition of the target product, which leads to an increase in energy consumption.

The closest in technical essence to the invention is a method of automatic control of the process of rectification by controlling the reflux costs for the upper and lower control plates. At the same time reflux consumption on top2

The new plate is stabilized, and the reflux flow rate to the lower plate is adjusted depending on the temperature on it and the pressure drop in the column [2].

The disadvantage of this method is

_{5 the} presence of increased energy losses due to the difficulty of maintaining the energy balance of the column as an inertial object, since a deliberately excessive amount of phlegm is supplied to the top plate.

In order to eliminate this drawback, the temperature difference between the upper and lower control plates is measured, depending on which the reflux flow rate on the lower plate is controlled, the temperature on the upper plate is stabilized, the concentration of undesirable impurities in the target product is measured and, when the value deviates from the specified value regulate the flow of phlegmy on the top plate, while changing the ratio of the costs of phlegm

20 on control plates.

The drawing shows a schematic diagram of the implementation of the method.

The method is as follows.

3

757171

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Temperature control on the upper control plate is produced using the controller 1, which receives a signal from the temperature sensor 2. Sensor 2 operates in conjunction with thermocouple 3 and acts through regulator 1 to feed most of the reflux to the upper control plate. Regulation of the temperature difference between the control plates is carried out using the controller 4, which receives a signal from the differential temperature sensor 5, which works in conjunction with the thermocouples 3 and 6 of the temperature and changes the reflux flow rate to the lower control plate. The ratio of reflux expenses in the range of 1: 0.3–0.4 is maintained by means of regulator 1, which affects the reflux flow rate (upper flow) and regulator 4, which acts on the lower flow of reflux. With an increase in the amount of undesirable impurities in the distillate, the flow rate of reflux on the upper control plate is adjusted using the analyzer 7 and the regulator 1, which leads to the required temperature change on this plate. The signal from sensor 5 acts on the temperature difference controller 4, which increases the reflux flow to the lower control plate, thereby changing the ratio of reflux streams. At the same time, the given constant temperature difference, depending on the thermophysical properties of the mixture to be separated, corresponds to different irrigation ratios. As a result, the content of undesirable impurities in the distillate is reduced and the necessary ratio of reflux flows is maintained in a given interval before the appearance of new disturbances. Then the control cycle repeats.

Using this method provides a reduction in reflux consumption by 8, ΟΙ 0.0%, reduction of energy consumption for carrying out the process by 15-20%, increasing the reliability and stability of the column and ensuring the production of the target product according to the quality of the required standard, which allows to obtain an economic effect at the rate of

y 48.9 thousand rubles. in year.

Claims (1)

Claim A method of automatic control of the rectification process by controlling ^{15 the} reflux consumption of the upper and lower control plates, characterized in that, in order to reduce the energy consumption for the separation process and obtain the target product of a given quality, change the temperature difference between the upper and lower control plates which regulate the flow of reflux to the lower plate and stabilize the temperature at the top of the plate was measured concentration of unwanted impurities in the target product ¹⁴ and, when deviation its value from the nominal value is controlled rate of reflux to the top tray and the reflux ratio of costs to the control plate.