SU683767A2 - Apparatus for automatic control of fractionating process - Google Patents

Description

one

The invention relates to devices for the automatic control of the rectification process and can be used in the chemical and petrochemical industries.

According to the main author. St. No. 475162, a device for automatic control of the rectification process is known, comprising a flow sensor, vapor temperature sensors emanating from the column and outdoor irrigation, a temperature difference converter, a square root extractor unit, a software unit connected to the external irrigation temperature sensor and multiplication units, one of which is associated with an external irrigation flow sensor and a square root extraction unit.

However, such a device does not provide high accuracy of regulation. This is explained by the fact that it does not take into account the influence of heat losses from the walls of the column into the environment on the change in the consumption of internal irrigation.

The purpose of the invention is to increase the accuracy of regulation.

This is achieved by the fact that the main author. St. 475162, containing a flow sensor, temperature sensors for vapors leaving the column and external irrigation. a temperature difference converter, a square root extraction unit, a software unit connected to an external irrigation temperature sensor, and multiplication units, an additional converter for temperature difference in the column and ambient air, a unit for calculating the change in the internal irrigation flow rate, and a summing relay. The input of the unit for calculating the variation in the internal irrigation flow rate is connected to the temperature difference converter in the column and the ambient air, and the output is connected to the control unit for the external irrigation flow rate through a summing relay associated with one of the 5 multipliers.

The drawing shows a block diagram of the device for automatic control of the rectification process.

The device contains temperature sensors 1 and 2, converters 3 and 4 of the difference

0 temperatures, external irrigation flow sensor 5, program block 6, multiplication blocks 7 and 8, square root extraction unit 9, unit 10 for calculating the variation of internal irrigation flow depending

from heat losses to the environment, summing up the relay 11, the regulating unit 12 and the actuator 13 on the line of irrigation.

The output of temperature sensors 1 and 2 is connected via temperature converter 3 to multiplication unit 8, the output of which is connected to summing relay 11. Temperature converter 3 is connected via program unit 6 to multiplication unit 7. Outflow sensor 5 is connected to multiplication unit 7, the signal from which through the square root extraction unit enters multiplication unit 8. The signal from the transducer 4 temperature differences in the column and the ambient air through the unit 10 for calculating the change in the flow rate of the internal irrigation flow In the summing relay 11, the output signal of which serves as a variable for the regulating unit 12 controls the actuator 13. To maintain a constant flow of internal irrigation, the device implements the dependencies derived from the thermal and material balances of the column. The consumption of internal irrigation depending on the temperature change of external irrigation is determined from the equation

4-At)

. R

internal

BIESHN

where r

vgr- - consumption of internal orion of the column;

ReweaJH. - consumption of external irrigation;

Cp is the specific heat of external irrigation 1i;

1C - heat of vapor conversion

leaving the column;

The difference is the temperature of the trees coming out of the column and outside irrigation.

In the presence of heat losses from) to the column to the environment, vapor condensation occurs in the column and thereby increases the consumption of internal irrigation, which for the selected cross section of the column is calculated from the general equation;

If -K

 It - t r91

.- (-co. i

where KT is the heat transfer coefficient of the walls of the colopne;

F - surface of the column; 7 - average heat of vaporization

vapors in the column;

(- average vapor temperature in the column;. - ambient temperature.

Consumption in renne1Ch) in the columns ie, it is possible to calculate from equations (1) and (2)

Krf

R int. - to

BHEWH- (y

Chr

G -

- env

The device works as follows.

The output signal from the external irrigation temperature sensor 2 enters the program block 6, where a signal is generated for correcting the indications of the external irrigation consumption transducer in terms of density, reduced to the actual external irrigation temperature. This signal enters multiplication unit 7, where it is multiplied by the signal from the sensor for flow and external irrigation is proportional to C11 (the square of the flow rate. In block 9, the square root extract signal is proportional to the flow of external irrigation KVNEII; the signal in multiplication unit 8 does not increase with an output value of

 3 transducer temperature difference with a proportional value (). In this multiplication unit, a value is obtained, which is proportional to the internal consumption of the system when taking into account changes in temperature)

5 extraordinary terms according to equation (1). Accounting for thermal losses from walls

 H CIRCLE ABOUT UIU СРСДу () DITs. And converters 4 topics in the column and surrounding OILE-oh vo) And block 10 calculating and

spirit (t

CP

OAGR

 the internal flow rate | | oron 1e, in which the value of Rgwyrp- (ttp.-,) is calculated. In total, 01 1 by the relay 11 O1 is determined by switching 1 to (for re 1 O 1, its block 12, with () the

SK F

R int. R vn1in. (1 + y - A t) + - - (tcp.- toKp.)

Adjustable-1st block 12 with the help of the operating mechanism 13 ensures 1-maintenance of the consumption of the internal irrigation at a given level.

Claims (1)

Invention Formula The device for automatic - () unravLenin prodessy rectification by ed. St. No. 475162, characterized in that, in order to improve the accuracy of the adjustment: 1, it additionally contains a temperature difference converter in the column and the ambient air, a unit for calculating the change in the consumption of internal irrigation and summing its relay, and an input for the unit for calculating the change in the internal flow The irrigation is connected to the generator of the temperature difference in the column and the ambient air, and the output is connected to the control unit by the external irrigation unit through a summing relay connected to one of the multipliers.