SU1301479A1 - Absorption control system in production of complex mineral fertilizers - Google Patents

Abstract

The invention relates to absorption control systems in the production of complex mineral fertilizers and avoids the discharge of hazardous effluent by improving the quality of control. The system contains a circuit for adjusting the density of the irrigating solution: sensor 5, meter 4 and regulator (P) 6 for the density of the solution, valve 7 for supplying phosphoric acid to the circulation drum 2, Block 8 for calculating the optimal solution density, which includes adder 9 and blocks 10 and 11 multiply. The system also contains a diluent flow control loop: sensor 15, meter 14, diluent flow rate P 16, and diluent supply (water) valve 17 to drum 2. Diluent flow rate calculation unit 18 is connected to the diluent flow rate control unit 18, which includes series-connected multiplication unit 19 adder o (l oo 4 (x

Description

21 and block 20 multiply. Sensors 12 and 13 of the concentration of ammonia and fluorine compounds, exhaust gases in the exhaust gases are connected at the output of the absorber, respectively, connected to blocks 10 and II multiplication. To the input of block 19, a meter 24 and a phosphoric acid concentration sensor 25 are connected. Sensor 12

one

The invention relates to the control of chemical processes, in particular the processes of absorption of ammonia and fluorine compounds, and can be used in the production of mineral fertilizers in the production of complex mineral fertilizers.

The purpose of the invention is to eliminate the discharge of hazardous effluent by improving the quality of the process control.

The qualitative management of the absorption process in the production of complex mineral fertilizers is coupled with the solution of two main tasks of maximally cleaning the gases entering the absorber from the ammonia and fluorine compounds contained in them, as well as coordinating the loads of absorption and neutralization of phosphoric acid to - the cost of production and the normal conditions of the neutralization process.

It is known that the degree of purification of ammonia from ammonia is directly dependent on the amount of phosphoric acid supplied to the acidification of the irrigating solution, i.e. One of the conditions for the best removal of ammonia is the maximum possible acid consumption for acidification. However, in practice, it is impossible to maintain maximum acid consumption. because of the violation of the technological regulations on the density of the irrigation solution. In addition, an increase in the consumption of phosphoric acid for acidification leads to an additional release of fluorine compounds dissolved in phosphoric acid, which causes

is connected with a correction block 26, consisting of multipliers 27 and 28 and summation blocks 29.30, a gauge 33 and an ammonia concentration sensor 34 are connected to a block 26, and a meter 31 and a flow sensor 32 are connected to block 27 gas to be purified, 1 sludge

O

five

0

five

five

.

35

0

increase in fluoride compounds in exhaust gases.

The drawing shows a functional diagram of the control system.

The technological scheme comprises an absorber 1, a circulation drum 2 and a tank 3 of the neutralization compartment.

The control system contains a meter 4, a sensor 5 and a regulator 6 of the density of the irrigating solution, a valve 7 for supplying phosphoric acid to the circulation drum 2 (a circuit for controlling the density of the irrigating solution), a block 8 for calculating the optimal density of the irrigating solution consisting of the adder 9, blocks 10 and 11 multiplying both sensors 12 and 13 of the concentration of ammonia and fluorine compounds in the exhaust gases, a gauge 14, a sensor 15 and a regulator 16 of the diluent (water) flow into the circulation drum 2. And a diluent supply valve 17 (the circuit is regulated and diluent consumption), diluent consumption calculation unit 18, consisting of multiplication blocks 19 and 20 and adder 21, meter 22 and sensor 23 of total phosphoric acid consumption at the absorption and neutralization stage, meter 24 and phosphoric acid concentration sensor 25, block 26 correction, consisting of blocks 27 and 28 multiplying and blocks 29 and 30 summation, the meter 31 and the sensor 32, the flow rate of the gas to be purified and the meter 33 and the sensor 34 of the concentration of ammonia in the gas to be purified.

The control system operates as follows.

Signals proportional to the concentration of ammonia and fluoride compounds in the exhaust gases are fed to the input of block 8, which calculates the task of controller 6 in accordance with the expression

p p (to Y - K Y),

 Mr. Wed gbix 2

where P is the average value of the density cf

those irrigating solution; weights;

Y VJ ,, - respectively, the concentration of 6 °

ammonia and fluoride compounds in exhaust gases,

If the content of ammonia in the exhaust gases has increased, and the content of fluorine compounds has remained at the same level, then the increased value of the signal proportional to the retention of ammonia in the exhaust gases is multiplied in block 10 by the weighting factor and fed into the positive chamber of the summator 9, B in the minus chamber of the adder 9 The signal multiplied by its weight in block 11 is proportional to the fluorine content in the exhaust.

Consequently, an increase in the ammonia content in the exhaust leads to an increase in the output signal of the adder 9. The regulator 6 forms a control action, which through valve 7 increases the consumption of phosphoric acid for acidification and stabilizes the density of the spray solution at a higher level. The addition of acid improves ammonia trapping.

The effect of fluoride compounds in exhaust gases on the density of the spray solution is reversed, i.e. an increase in the fluorine compound content in the exhaust leads to a decrease in the consumption of phosphoric acid for acidification and stabilization of the density of the spray solution at a lower value.

Signals proportional to the concentration of ammonia in the exhaust and in the cleaned gas, as well as the flow rate of the gas to be purified, are fed to the inputs of the block 26

correction, which is calculated

the amount of phosphoric acid bound by ammonia as a result of chemisorption in absorber 1 (output signal of unit 28) corresponded to the expression:

With S (Y: - ,,) -R.

where S is the proportionality coefficient;

 ABOUT

 -5 20

-30 35

40

0

five

Y is the concentration of ammonia in the gas to be purified;

G - gas consumption.

The output signal of the correction unit 26, formed by the adder 30, is proportional to the actual consumption of phosphoric acid L and is calculated from the dependence L L., -

to

where L is the total consumption of phosphoric acid at the stage of neutralization and absorption, is fed to the input of the diluent consumption calculation unit 18.

The second input of block 18 receives a signal proportional to the concentration of phosphoric acid from sensor 25 through meter 24. Block 18 calculates the diluent flow into the circulation drum 2 from such a calculation that phosphoric acid is diluted to 47% at the output of tank 3 (the routine value for the neutralization stage ).

I I3 (5 1 -b -k 47

where C is the concentration of phosphoric acid at the entrance to the installation.

The flow stabilization circuit, consisting of a meter 14, a sensor 15, a regulator 16 and a valve 17, stabilizes the diluent flow rate at the desired value.

The consumption of phosphoric acid through the sensor 23 into the tank 3 is set by the load of the neutralization stage (the regulator is not shown), and the change in the acid consumption by the controller 6 is not reflected in the total acid consumption through the sensor 23.

The use of the proposed system makes it possible to optimally conduct the process of purifying gases from impurities of ammonia and fluorine compounds, to precisely match the loads of the neutralization and absorption stages, which generally improves the quality of regulation. An important result of improving the quality of regulation is to prevent pollution of the environment, since the discharge of hazardous effluent is completely eliminated.

Claims (1)

Invention Formula The absorption process control system in the production of complex mineral fertilizers, containing sensors for the concentration of ammonia and fluoride compounds in exhaust gases, combi51 through the unit for calculating the optimum density of the irrigation solution with a chamber for setting the density regulator of the irrigation system connected by its chamber; Variable to the sensor for the density of the irrigating solution; and output to the valve for supplying phosphoric acid to the circulation drum, a sensor for the concentration of phosphoric acid, connected to the first input of the diluent consumption calculation unit, the output of which is connected to the regulator chamber. filing diluent connected .. by its camera. Variable to the diluent flow sensor, and output to the diluent supply valve, and the sensor for total phosphoric acid consumption in the absorption and neutral compartments. a distinction 4TOj with a circuit to prevent the discharge of hazardous waste by improving the quality of the process control, the system further comprises sensors for the flow rate of the gas to be purified and the concentration of ammonia in it and a correction unit, while the ammonia concentration sensor in the exhaust gases is connected in parallel with the first input of the correction unit whose other inputs are connected to the sensors of the flow rate of the gas to be purified, the concentration of the ammonia in it and the sensor for the total consumption of phosphoric acid in the absorption and neutralization compartments, and the output of the correction unit is associated with the second input house unit diluent consumption calculation.