SU889613A1 - Method of automatic control of neutralizing process - Google Patents

Description

(5) AUTOMATIC PROCESS MANAGEMENT METHOD

NEUTRALIZATION

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The invention relates to methods for the automatic control of chemical technological processes and can be used in the chemical industry, for example, in the production of ammonium nitrate.

There is a known method of controlling the neutralization process in the production of ammonium nitrate by stabilizing the pH value of the solution at the reactor exit by varying the acid consumption and simultaneously introducing a correction for ammonia consumption, taking into account the total load on peaKTopJ 1J.

The closest technical solution to the proposed is a method of automatic control of the neutralization process in production. ammonium nitrate by adjusting the cost of neutralizing and neutralizing reagents 2.

The disadvantages of the known methods are the instability of the neutralization process and the large losses of associated nitrogen caused by it due to the substantial nonlinearity of the pH dependence on the composition of the solution at the outlet of the reactor. The main disadvantage is due to the specific nature of the pH dependence, which is the reason for the significant decrease in the monitoring volume, if necessary, to conduct a neutralization process in the usually acidified mode of operation. For example, the achievable accuracy of measuring acid in a solution of ammonium nitrate when using a standard pH meter in terms of acid is ± 3 g / l with an actual content of 6 g / l. In addition, when the environment changes from neutral to

Claims (2)

20 acidic, the gain is changed in 3535 ra. At the same time, it is known that common industrial automation, at best. 3 Provide satisfactory quality control when the gain of the system varies by no more than 15 times. These factors are mainly the cause of the unstable operation of the neutral reactors and the associated significant losses of raw materials. The purpose of the invention is to reduce the sweat of bound nitrogen by increasing the accuracy of controlling the pH of the neutralized solution. The goal is to achieve that a sample of a neutralized solution is mixed with neutralizing reagent in a given ratio, the pH of the mixture is measured and the cost of neutralizing neutralizing reagents is adjusted depending on the difference between the pH of the mixture and the specified potential corresponding to the equivalence point of the mixture. In this case, the specified ratio of the sample of the neutralized solution and the neutralizing reagent is set depending on the specified concentration of one of the components in the sample of the neutralized solution. The drawing shows a functional diagram of the implementation of the method. Neutralizing reagent nitric acid 2 and neutralizing reagent ammonia 3 flow into reactor-neutralizer 1, costs of which are measured respectively by flow meters 4 and 5. Changing the supply of nitric acid is performed by valve 6 at the command of regulator 7, and feed; ammonia by valve 8 according to the command S of the regulator 9, the ratio of the flow, corrected by the regulator 10. Sample 11 of the analyzed solution at the exit from the neutron of the lysator 1 is fed to the mixture in a given ratio with the neutralizing reagent 3. The ratio of these flows determines with a batch mixer 12. The analysis of neutralized Totok is performed by a pH sensor 13. The potential corresponding to the equivalence point of this mixture is set by the setting device 1. The method is carried out as follows. The amount of neutralizing reagent entering the metering mixer 12 is determined from the condition. 4 stoichiometric ratio to the specified amount of neutralized reagent, containing in the sample taken P, In this case, if in the solution coming out of the reactor neutralizer 1, the content of the component corresponds to the specified, then at the outlet of the mixer 12 the pH sensor 13 fixes the potential corresponding to the equivalence point . In the absence of imbalance with the value of the task set by the setpoint device, the regulator 10 leaves at the same level the signal that determines the ratio of the main flows of reagents. If in the solution leaving reactor-neutralizer 1, the content of the component differs from the predetermined value, an imbalance of signals at the output of sensor 13 and installed on the setting device 14 is formed, which determines the magnitude and direction of change of the signal at the output of regulator 10. After bringing the neutralizing reactor 1 to a predetermined mode of operation, determined by the content of the component in the solution, the output of the regulator 10 is fixed at a new level. If it is necessary to change the content of the component in the solution at the outlet of the reactor-neutralizer 1, a new ratio of costs to the neutralizing reagent is set on the dosing mixer 12. Thus, in the process of regulating the neutralization process at the outlet of the dispenser-mixer 12, the solution environment, controlled by the sensor 13, varies from acidic to ammonia near the equivalence point, ensuring the normal operation of the system as a whole, but at the same time in solution at the outlet of the reactor neutralizer 1 is always acidic. Using the method, as shown by the results of preliminary tests of the neutralization process control system, reduces the loss of bound nitrogen by 30 kO% compared to the known. Claims 1. A method for automatically controlling neutralization processes by adjusting the cost ratio of neutralizing and neutralizing reagents, characterized in that, in order to reduce losses 588961 bound nitrogen by increasing the accuracy of controlling the pH of the neutralized solution; a sample of the neutralized solution is mixed with a neutralizing reagent in a given ratio s; the pH of the mixture and corrections are measured; The ratio of the costs of neutralizing and neutralizing reagents depends on the difference between the signals of the pH of the mixture and the specified potential, corresponding to the equivalence point of the mixture. 2. The method according to p. 1, about tl and h ayusch and with the fact that the specified ratio of 3 " The sensitivity of the sample of the neutralized solution and the neutralizing reagent is set depending on the given concentration of one of the components in the sample of the neutralized solution. Sources of information taken into account in the examination 1. USSR author's certificate №, cl. C 01 B 21 / A8, 1970. 2. USSR author's certificate number 41259, cl. From 05 To 1/00, 1972.