SU893975A1 - Method of automatic control of ammonium phosphate production process - Google Patents

Description

I

The invention relates to the automation of the neutralization process, and more KoincpeTHO to the automation of the production of ammophos by neutralizing phosphoric acid with ammonia, and can be used in the chemical industry, in particular in the production of mineral fertilizers.

There is a known method for automatically controlling the production process of granular fertilizers by stabilizing the ratio of the consumption of phosphoric acid and ammonia by affecting the supply of ammonia depending on the pH value, taking into account the humidity and electrical conductivity of the neutralized pulp 13.

There is also known a method for automatically regulating the process of producing ammophos, including regulating the ratio of the consumption of phosphoric acid and ammonia with correction for the temperature of the product in the reactor and the consumption of phosphoric acid 121.

A disadvantage of the known methods is that the direct adjustment of pH and temperature in the reaction zone is not carried out, and only correction is carried out on these parameters. With the inertia of the object and the presence of a lag time, such control methods do not provide rapid control of the output parameters (pH and temperature).

In addition, the absence of direct control loops in pH and temperature does not allow the introduction of correction signals from disturbances (for example, consumption and concentration of phosphoric acid) affecting these parameters.

Claims (3)

There is also known a method for controlling the process of obtaining ammophos by neutralizing phosphoric acid with ammonia, maintaining the desired temperature in the reaction zone by varying the heating steam consumption with correction for the consumption of phosphoric acid and the viscosity of the resulting ZD product. The disadvantage of this method is the absence of a pulp pH control loop and, accordingly, an account of the influence of disturbances on this parameter; temperature control is carried out without taking into account changes in the concentration of phosphoric acid. In addition, the viscosity adjustment of the product is technically difficult to implement, since a small change in temperature in the reaction zone or in the environment causes sharp fluctuations in viscosity. When ammophos is obtained, it is desirable to take into account the change in the density of the output product. The purpose of the invention is to improve the quality of the output product by increasing the control accuracy. This is achieved by additionally regulating the pH of the pulp by varying the ammonia supply with a correction for the flow rate and concentration of phosphoric acid. In addition, the steam supply is additionally adjusted for the concentration of phosphoric acid and the density of the output product. The drawing shows a schematic diagram of the system for automatic control of the neutralization process. The method is carried out as follows. The neutralization process takes place in a high-speed ammonizer-evaporator 1. Phosphoric acid and ammonia are fed through a nozzle 2 into the reaction tube 3. The resulting mixture is heated in a heat exchanger 4. The pH value is measured by sensor 5 and controlled by regulator b by acting on the ammonia supply valve 7 . The regulator 6 also receives correction signals from the flow sensor 8 and phosphoric acid concentration through the compensators 10 and 11, respectively. The temperature of the pulp at the outlet of the heat exchanger 4 is measured by the sensor 12 and adjusted by the regulator 13 by acting on the steam supply valve 14. The regulator 13 also receives correction signals from the sensors: 8-flow through the compensator 15; 9concentration of phosphoric acid through the compensator 16; 17 Density. Amm phosphate pulp. When the flow rate and concentration of phosphoric acid from sensors 8 54 9 are changed through compensators 10 and 11, the signals to regulators 6 and 13 are lowered, which, in turn, compensate for changes in consumption and concentration of osphoric acid by changing ammonia and steam, respectively. When the density changes in the pulp from the density sensor 17, a signal is sent to the regulator 13, which compensates for the change in the density of the additional HbiM by changing the feed. Thus, the supply of correction signals for the consumption and concentration of phosphoric acid through the compensators 10, 11, 15, and 16 makes it possible to eliminate the influence of these disturbances on the pH and temperature in the reaction zone without causing their deviations. When implementing the proposed method, the control accuracy is increased, and this allows improving the quality of the output product. Claim 1. A method for automatically controlling the process of obtaining ammophos by neutralizing phosphoric acid with ammonia, including adjusting the temperature in the reaction zone by varying steam consumption with correction for phosphoric acid consumption, characterized in that, in order to improve the quality of the product by improving the control accuracy, the pH of the pulp by changing the flow of ammonia with a correction for consumption and concentration of phosphoric acid. 2, the method according to p. 1, about tl and h and y and with the fact that the steam supply is additionally adjusted for concentration. phosphoric acid and the density of the output product. Sources of information taken into account during the examination 1. USSR author's certificate No. 575343, cl. C 05 C 1 / OO, 1977 2. USSR author's certificate number 564296, cl. C O5 B 7/00, 1977. 3. USSR author's certificate number 471299, cl. From 01 to 25/18, 1975.