SU1745730A1 - Method of process control in solvent refining by distillation - Google Patents

Abstract

Usage: in the chemical and petrochemical industries of the industry, 2 in particular in the production of SKI-3 rubbers, the ACS in the polymerization process, and the purification of solvents from impurities by rectification. In the method, upon reaching the dimer concentration of the upper limit value, the reflux consumption is left unchanged. If the reflux number then exceeds the predetermined permissible value, the steam supply is continued to be adjusted for the solvent consumption with a positive sign, and for converting the concentration of dimers to the upper limit value and / or the reflux number for the upper permissible value — with a negative sign, with a further decrease in concentration dimers below the lower limit value, the flow rate is adjusted depending on the solvent consumption and the reflux number with a positive sign. 1 h p f-ly ,. cr s

Description

The invention relates to the regulation of technological processes and can be used in the chemical and petrochemical industries, in particular in the production of SKI-3 rubbers, SKDs, and others in the polymerization process during the purification of solvents (toluene, isopentane) from impurities by rectification.

Methods are known for regulating solvent purification processes by rectification.

A disadvantage of the known methods is the low economic efficiency of solvent purification.

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

The circuit includes a column 1, a boiler 2 with a steam flow control loop in the boiler, consisting of a sensor 3 (DKN and DS-P), a regulator 4 (PV10.1ES Pr 3.24). control valve 5, a circuit for controlling the flow of bottoms, consisting of sensor 6 (DKN and DC-P), controller 7 (PV10.1E with PR3.24) and control valve 8, sensor 9 (DM-P) of the liquid phase in column 1 and its associated regulator 10 (PV10.1E with PR3.21), steam phase condenser 11, reflux flow control loop consisting of sensor 12 (DKN and DC-P), regulator 13 (PV10. 1E with PR3.24) and control valve 14, sensor 15 concentration of dimers in distillate (chromatograph

Vj b

cl

xj cj o

Neftekhim-200 or EPDM with a pneumatic storage device on USEPPA elements) and its associated controller 16 (PVSU1E with PR3.21), maximum signal limiter 17 (PP 11.1), minimum signal limiter 18 (PP11.1 ), the distillate flow sensor 19 (DKN and particle board), reflux number determination unit 20 (multiplier-separating device PF1.18), minimum signal limiter 21 (PP 11.1), control unit 22 (PR1.5), unit 23 summation (PF1.1), solvent flow sensor 24 (DKN and DC-P), controller 25 (PV 10.1 Oe with PR3.21), switch 26 signals (two switches neither PP2.5), block 27 summation (PF 1.1) and block 28 control (PR1.5).

The method is carried out as follows.

The solvent is fed to the distillation column 1, the flow rate of which is measured by the sensor 24. The steam flow to the boiler 2 is stabilized by the controller 4, which acts on the valve 5 according to the signal from the sensor 3 of the flow. From the bottom of the column, bottom residues are removed, the flow rate of which is measured by sensor 6 and stabilized by regulator 7 acting with valve 8. As solvent consumption increases, regulator 25 adjusts steam flow to boiler 2 by a signal through adder 27 and regulator 4 in the direction of increase steam consumption. The inertia of action along this contour with an increase in solvent consumption leads to an increase in the level in column 1.

The sensor 9 of the liquid phase level in the column outputs a signal to the regulator 10. When the level in the column exceeds a predetermined value, the regulator 10 corrects the task to the regulator 7, increasing the output of the bottoms and vice versa. At the exit of column 1, the vapor phase enters the condenser 11, from which the distillate goes to polymerization or additional drying. The distillate flow rate is measured by the flow sensor 19. Part of the distillate is bypassed from this pipeline and used as reflux, the flow rate of which is measured by sensor 12 and stabilized by regulator 13 acting on valve 14. Regulator 16 according to information from a dimer concentration sensor in distiller 15 generates a correction signal to the regulator 13.

With increasing concentration in comparison with its given value, the reflux consumption increases and vice versa. With an increase in the concentration of dimers above the upper limit value. 1 wt.% Of dimers, the signal limiter 17 leaves the reference to controller 13 unchanged, and the reflux consumption is stabilized. By reducing the concentration of dimers, the effect of the regulator 16 on the regulator 13 is restored. 5 With sensors 12 and 19 and block 20

determination of reflux number determine reflux number f:

ten

, “D

where Sf - consumption of phlegm;

Cd - consumption of distillate, and through the switch 26 give the signal

from block 20 to block 27 summation with a positive sign, affecting the increase in steam consumption in boiler 2 with an increase in the reflux ratio. In control block 22, the determined value F of the reflux number is compared with its allowable value Fdop (in the example FDoP 8).

If the reflux number is less than or equal to the acceptable value, the effect

regulator 4 is implemented with a positive sign.

If the reflux number is greater than the allowable value, then the signal from the control unit 22 by the switch 26 changes the negative signal, since the adder 23 is connected to the adder 27 through the switch 26, which changes the sign of the signals 18 and 21. at concentration values above the upper limit value Cgr of 0.01 mass% of dimers, the concentration increase signal, the concentration increment D C is fed to the adder 23. which is fed and / or the signal is exceeded by a reflux number given Fdop 8 th value, i.e. F through the limiter 21 signal to a minimum. Thus, the signals from blocks 21 and 18 are generated and fed to an adder 23

only when C and F exceed the maximum allowable values.

Thus, the switch 23 connects to the adder 26 either block 20 or adder 23. which reduces the consumption of steam in the boiler 2 columns in proportion to the expression:

Ki DC + K2DF,

where Ki and K2 are the coefficients of proportionality;

D C is the increment in the concentration of dimers in the distillate above the upper limit value;

Df is the increment of the reflux of the permissible value.

When the dimer concentration drops below the limit value (0.05 wt.% Dimers) by the signal from control unit 28, switch 26 reverses the correction signal and sends to the adder 27 only a reflux ratio value signal with a positive sign from the solvent flow meter 24 through regulator 25.

Claims (1)

Invention Formula The method of controlling the solvent purification process by rectification, including regulation of steam consumption, consumption of the bottoms residue depending on the level in the column, determination of the reflux number and comparison with the acceptable value, regulation of the reflux consumption depending on the concentration of dimers in the distillate, characterized in , In order to reduce energy consumption, the solvent consumption is measured, the upper and lower boundary values of the concentration of dimers in the distillate and the reflux number are set. When the dimers concentration of the upper limit value is reached, the reflux consumption is left unchanged, when the reflux number exceeds the specified acceptable value, the steam consumption is adjusted according to consumption solvent with a positive sign, when the concentration of dimers in the distillate exceeds the upper limit value and / or the reflux number exceeds the upper limit value tim - with a negative sign, and for reducing the concentration of dimers below the lower limit value of the steam flow is adjusted depending on the flow rate of reflux solvent and with a positive sign. Distil / R