SU1119979A1 - Method of automatic control for process of obtaining sodium nitrate - Google Patents

Abstract

A method of automatic control of the process of producing sodium nitrate by controlling the ratio of the flow rates of weak nitric acid and nitrite-nitrate solution by affecting the flow of weak nitric acid into the inversion column, stabilizing the pressure of nitrous nitrous gases at the inlet of the column and adjusting the flow of the swede mask. The pH of the solution of nitrate salts at the outlet of the neutralizer, characterized in that, in order to reduce the expenditure coefficients for a weak nitric acid and soda per unit of product by increasing the accuracy of regulation, the ratio of the consumption of weak nitric acid and nitrite-nitrate solution is adjusted by the temperature difference of the nitrite-nitrate solution, at the entrance to the inversion column and in the middle of the column, the soda solution is adjusted according to the composition of the solution sodium nitrate at the inlet to the neutralizer.

Description

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The present invention relates to a method for automatically controlling the process of producing sodium nitrate and can be used in chemical applications.

There is a known method for automatically controlling the process of obtaining sodium nitrate by adjusting the ratio of the flow rates of weak nitrogen and nitrite-nitrate solution -tJ

The disadvantage of this method is that there are significant costs of weak nitric acid per unit of product and soda solution, necessary for its subsequent neutralization.

The closest to the proposed technical essence and the achieved effect is the method of automatic control of the process of obtaining sodium nitrate by adjusting the ratio of the consumption of weak nitric acid and nitrite-nitrate solution by inversion, stabilizing the pressure of tail nitrous gases at the column inlet and controlling the consumption of soda solution to the neutralizer depending on the pH value of the solution of nitrate salts at the outlet of the neutralizer 2.

The disadvantage of this method is the presence of significant consumption coefficients for weak nitric acid and soda solution per unit of product.

The purpose of the invention is to reduce consumption coefficients for weak nitric acid and soda solution per unit of product by means of control accuracy.

The goal is achieved by the fact that the ratio of the consumption of weak nitric acid and nitrite nitrate solution is adjusted by the temperature difference of the nitrite-nitrate solution at the inlet to the inversion column and in the middle of the column, and the flow rate of the soda solution is adjusted by the composition of the sodium nitrate solution at the inlet to the neutralizer.

The drawing shows a schematic diagram of a device implementing the method.

The scheme contains pipelines for supplying a solution of nitrite-nitrates 1, weak nitric acid 2, heat carrier 3, and tail nitrous gases 4

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output gases 5, a solution of nitrite nitrates 6, a solution of soda 7 and a solution of nitrate salts 8, an inversion column 9, a preheater 10, a neutralizer 11, flow sensors 12-1A, respectively, of a solution of nitrite-nitrates fed into and out of the column, and consumption of nitric acid, sensors 15–17 tempo (About the temperature of the inlet to the inversion column 9, respectively, before and after the preheater 10, pressure sensor 18 of the tail gases, sensors 19 and 20 of the composition of the nitrate solution, j nitrite and sodium salt solution, multiplication unit 21, controllers 22–24 times Water, respectively, nitrite-nitrate solution, nitric acid and salt solution, regulator Q torus 25 pressure of tail nitrous gases, regulator 26 temperature of solution of nitrite-nitrates and executive mechanisms 27-31 corresponding fluids.

5 The method is carried out as follows.

The heated nitrite-nitrate solution (PHN), the flow rate of which is measured by the sensor 12, enters the inversion column 9 via pipeline 1, where it also enters. pipeline 2 is weak nitric acid, the flow rate of which is measured by sensor 14. The PHN entering the inversion column 9 is regulated

5 through the regulating device 22 by the actuator 27. From the middle of the column 9, the inversion of the PHN enters the heater 10, which supplies the temperature-temperature heat carrier (for example, steam) through the pipeline 3. Preheat the PMI to the required temperature (for example), which is measured by the sensor 17 and regulated with the aid of a temperature controller of temperature 26 by an actuator 29, it returns to the inversion column 9.

Inversion column 9 is fed through the pipeline 4 tail nitrous

0, the gas whose pressure is measured by the sensor 18 and regulated through the regulator 25 by the actuator 30.

Sensors 15 and 16, measuring accordingly

the entrance to the inversion column and at the exit from the middle of the column are interconnected in series with such

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thus, to ensure the temperature difference measured by thermocouples. The signal from the differential turn on of two thermocouples is a corrective for the ratio of the flow rates of PHN and weak nitric acid.

From the inversion column 9, a solution of sodium nitrate, whose composition is measured by sensor 19 (for example, pH), flows through conduit 6 to the neutralizer 11, where soda solution flows through conduit 7. The consumption of PHN in the neutralizer 11 is measured by the sensor 13. From the neutralizer 11, a solution of nitrate salts (RIS) is fed through line 8 to the residue. The composition of the PHS (e.g., pH) at the outlet of the neutralizer is measured by sensor 20.

When measuring the flow rate of the PHN, the signal from the sensor 12 enters the flow controller 23, which also receives signals about the magnitude of the flow of weak nitric acid from the sensor 14 and the value of the temperature difference RNI before the entrance and after leaving the center of the inversion column 9. The flow controller 23 generates a regulating effect on the actuator 28 located on the pipeline 2 of nitric acid. An increase in the flow rate of PHN produces a signal to increase the flow rate of weak nitric acid, and a decrease in the flow rate of PHN produces a decrease in the flow rate of nitric acid, while in both cases this increase or decrease in nitrogen flow rate is corrected

depends on the magnitude of the temperature difference PHN to and from the center of the inversion column. An increase (decrease) in PHN and low nitric acid consumption will cause a decrease (increase) in PHN temperature in the inversion column, which are measured by sensor 16. In addition, an increase (decrease) in PHN cost

and nitric acid will cause an increase (decrease) in the consumption of PHN in the neutralizer 11, which is measured by sensor 13, and its composition (for example, pH) is measured by sensor 19.

Signals from sensors 13 and 19 enter the salt solution flow regulator 24, which also receives a signal from sensor 20 about the PHC composition (for example; pH) at the output of the neutralizer 11. The flow regulator 24 generates a signal to the actuator 31, increasing (decreasing) a) soda solution consumption depending on the product of signals from sensors

13 and 19, which is formed by the unit for correcting the composition according to the signal from sensor 20.

The economic effect of the method of controlling the process of obtaining sodium nitrate is to reduce the expenditure ratio for weak nitric acid by 0.01 ton / ton due to the possibility of more accurate maintenance of its ratio with the consumption of PHN and to reduce the expenditure coefficient for soda solution by 0.01 ton / ton due to a more accurate maintenance of its ratio with the consumption of PHC.

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Claims (1)

METHOD FOR AUTOMATIC CONTROL OF THE PROCESS FOR PRODUCING SODIUM NITRATE by controlling the ratio of the rates of weak nitric acid and nitrite nitrate solution by affecting the supply of weak nitric acid to the inversion column, stabilizing the pressure of the tail nitrous gases at the inlet of the column and regulating the dependence of the flow rate of the soda solution in the don the pH of the solution of nitrate salts at the outlet of the de-neutralizer, characterized in that, in order to reduce the expenditure coefficients for weak nitric acid and a solution with odes per unit of product by increasing the accuracy of regulation, the ratio of the flow rates of weak nitric acid and nitrite nitrate solution is adjusted by the temperature difference of the nitrite nitrate solution at the inlet to the inversion column and in the middle of the column, and the flow of soda solution is adjusted by the composition of the sodium nitrate solution at the inlet neutralizer. , SU _n „1119979 1 11