SU1364357A1 - Method of controlling the process of absorption-desorption - Google Patents

Abstract

The invention relates to a method for controlling the process of absorption - desorption, can be used in the petrochemical, chemical industry and allows optimizing the process by increasing its selectivity, reducing energy costs and product losses. The method is implemented by a device that includes a flow control loop for a naschennogo absorbent with a level correction in the absorber 1, a regulator (P) 10 connected to the sensor (D) 8; a control loop for the consumption of the regenerated absorbent with a correction for the concentration of the target product in the exhaust gases P 7, associated with A 14 concentration through the control action formation unit 17; the flow control loop of the selected absorbent with a level correction in the tank 4JP26, connected to the level sensor, the steam flow control loop in the boiler 3; Flow rate P 12 associated with current enthalpy difference calculation unit 22. 1 il. S Yu

Description

Gas

& d @ d

4ib

CO C71

4j

  13

The invention relates to methods for controlling chemical and technological processes and can be used in the petrochemical, chemical and petrochemical industry. The purpose of the invention is to optimize the process by increasing its selectivity and reducing energy consumption and losses of the target product.

The drawing shows a schematic diagram of the implementation of the method of controlling the process of absorption-desorption.

Q - regenerated consumption

absorbent, kg / h; - The degree of na-stage performance. The temperature of the regenerated absorbent supplied to the absorber is controlled by the supply of the cooling agent with a humulator 9, the task for which is the signal from block 25, in which the difference between the current is calculated; the value of the thermal effect of the absorption process calculated by block 24 and the given value of the thermal effect obtained by calculating the thermal

The process of absorption-desorption wire- 5 balance. Block 24 implements at the same time

d in an installation that contains absorber 1, desorber 2, boiler 3, tank 4, heat exchanger 5, reflegmator 6..

The process is controlled by regulator 7 of the consumption of the regenerated absorbent, regulator 8 of the level and absorber, regulator 9 of the temperature of the regenerated absorbent, regulator 10 of the consumption of saturated absorbent with absorption, hydraulic lock 11 by regulator 12 of the steam consumption in the boiler, regulator 13 of the level desorber, measuring the concentration of the target product 14 in the exhaust gases, the unit 15 for calculating the absolute increase in the absorbent, the unit 16 for calculating the degree of saturation of the absorbent, the unit 17 for controlling the formation on the consumption of the regenerated absorbent, the distillate consumption meter 18, the comparison unit 19 by the feed absorber consumption meter 20, the absorber efficiency calculation unit 21, the current enthalpy difference calculation unit 22, the adder 23, the absorption effect current value thermal calculation unit 24, the task setting unit 25 and regulator 26 consumption of the absorbent taken.

Absorption process control; the change in the supply of the absorbent by the regulator 7, the task is the signal from block 17, which is formed using the concentration of the target product in the exhaust gases and the degree of saturation of the absorbent, calculated using blocks 15, 16, 10 and 7 by the ratio

5 QHiQf

QH

(one)

where Q is the consumption of the absorbent, kg / h;

following algorithm:

uq, QM-t ° -K, -Qp-tp-K

kcal

(2)

0

0

five

where t is the temperature of the saturated absorbent measured in the cube of the absorber. WITH;

tp is the temperature of the regenerated absorbent measured at the entrance to the heat exchanger of the absorber, C; K ,, Kg - constant coefficients,

kcal .kG ° C

The thermal effect setpoint is calculated from the heat balance equation of the absorption process:

i,. t K, -Qp. , t (qr (3)

5 where Q

0) H25

Hor-tj

from

0

TO.

exhaust gas consumption, kg / h;

the flow rate of gas entering the absorber, kg / h; temperature of the gas entering the absorber. WITH; heat capacity of the incoming

to absorber

kcal gas, ----.

To ensure the normal functioning of the absorption process, the level in the absorber cube is additionally stabilized by the regulator 8 and the pressure in the absorber by the hydraulic lock 11.

The control of the desorption process is carried out by changing the supply of the coolant to the boiler 3 by a controller 12, the task for which is the signal from unit 23 representing

is the sum of the signals from blocks 22 and 19. In block 22, the current enthalpy difference of the saturated and regenerated absorber flows is calculated by the ratio

de

 Wg

k, .k and tu „E. kcal ... h

-K t, (4)

1 m about kg

 constant coefficients, kcal

temperature of the saturated absorbent, measured at the code in the desorber. WITH; t is the temperature of the regenerated absorbent measured in the desorber cube,

with.

C. FDI ,,

set point ental kcal

kg

In block 19, a signal is generated that is proportional to the efficiency of the desorber operation. The efficiency of the desorber is estimated by the difference in the distillate consumption measured by block 18 and the distillate consumption obtained by calculating from the material balance of the desorber in block 21, which implements the following algorithm:

(QH-Qp) + Q "-Qor-Qa o, (5)

de Qn h., consumption pbdpitki, -;

consumption of absorbed 0 ,, .30

one

kg distillate consumption, - ;.

Dp calculating material ba40

The purpose of the desorption process is to reduce energy consumption and price loss in block 15, in which the left-hand product is produced, additionally measure the cost of the estimated and tore saturated saturation absorbent temperature, and block 21, in which the difference is the flow rate of the feed absorbent is added and the flow rate of the absorbent taken out is measured, as measured by block 26.

The use of regulating the supply of coolant to the desorber, depending on the current enthalpy difference between the desorbed and saturated absorbent, allows the heat to be consumed as much as necessary to heat the saturated absorbent to the boiling point, and to introduce a correction for the current efficiency

45

50

bent in the absorber cube and at the inlet to the desorber and the regenerated absorbent in the desorber cube, while the flow rate of the coolant is controlled depending on the temperature difference between the saturated absorbent at the inlet to the desorber and the regenerated absorbent, in the desorber cube with correction for the distillate deviation from the specified, the difference between the product of costs for the temperature of the absorbed and regenerated absorbent during the absorption process and the temperature of the regenerated absorbent at the inlet to the absorber is adjusted with correction according to the deviation from the given value of the calculated difference.

desorber operation allows you to provide the amount of heat that is required

4357. four

Dimo to evaporate. In addition, regulation of the temperature of the absorber supplied to the absorber, depending on the deviation of the current thermal effect of the absorption process from a predetermined value, allows increasing the selectivity of the process and thereby reducing the circulation ratio of the absorbent, which allows Q to have energy savings per unit as a whole and to reduce the loss of energy for the target product.

The present invention allows controlling the process of absorption-desorption of the B mode, which is the closest to the optimal one, and thereby reduces energy consumption.

Claims (1)

Invention Formula The method of controlling the process of absorption and desorption of gases by adjusting the flow rate of the regenerated absorbent to the absorber, taking into account the content of the target product in the exhaust gases, controlling the flow rate of the coolant to the desorber boiler, taking into account the flow rates of the regenerated and saturated absorbent and distillate, measuring and controlling the temperature of the regenerated absorber the entrance to the absorber, characterized in that, in order to optimize the process by increasing its selectivity and 40 g reduce the energy consumption and loss of the target product, additionally measure the temperature of the saturated absorption 45 0 bent in the absorber cube and at the inlet to the desorber and the regenerated absorbent in the desorber cube, and the flow rate of the coolant is controlled depending on the temperature difference between the saturated absorbent at the inlet to the desorber and the regenerated absorbent, in the desorber cube with a correction for the distillate deviation from the specified, calculated the difference between the product of costs for the temperature of the absorbed and regenerated absorbent during the absorption process and the temperature of the regenerated absorbent at the inlet to the absorber is adjusted with correction according to the deviation from the given value of the calculated difference.