SU532383A2 - The method of automatic control of the evaporator-crystallizer - Google Patents

Description

(54) METHOD FOR AUTOMATIC REGULATION OF THE WORK OF THE SUPPORT-CRYSTALIZER

but close relationship (pair correlation coefficient, 8). Therefore, the stabilization of the acidity of the mother liquor of the pulp, the automatic measurement of which with existing measuring means is extremely difficult, is ensured by the stabilization of an indirect value — the acidity of the stock solution, which is easily measured automatically.

The drawing shows a functional diagram of the system implementing the described method.

The initial solution from feed collector 1 is fed to an evaporator-crystallizer 2, in which pulp is generated under vacuum conditions created by using surface condenser 3 and steam ejector 4 and then fed to centrifuge 5 for flushing salts with water contained in the pulp, followed by separation otfugovannogo solution. Electrical signals from the output transducers of the induction flow meters 6 and 7, proportional to the measured values of the pulp flow and the initial solution, are fed to electropneumatic transducers 8 and 9, in which they are transformed into proportional pneumatic signals. Pneumatic signals from transducers 8 and 9 are supplied to the comparison chambers of the regulating unit ratio 10. Depending on the predetermined ratio of these values, the regulating unit 10 generates the corresponding command signal to the regulating valve 11. Under the action of this signal, the valve moves, changing the solution flow into the apparatus until until the specified ratio between the flow rate of the initial solution and the pulp is established. The signals from the flow meters 12 and 13 are fed to register the measured flow rates of the used water and heating steam to the secondary devices 14 and 15. At the same time, the signal from the flow meter 12 is fed to the summing unit 16, in which, in accordance with the incoming signal, a correction pulse is generated. a ratio of the regulating block 17. Signals from an electropneumatic converter 9 and an output converter of the flow meter 13 are received in the variable chamber of this block. Depending on the ratio of the input signal In the control unit 17, a control signal is generated to the control valve 18. Under the action of this signal, the valve moves to change the flow rate of heating steam until the ratio between the flow rates of the solution and the heating steam is established, in accordance with the amount of evaporated water at a given time. The pneumatic signal from the output transducer of the vacuum gauge 19, which is proportional to the measured vacuum value in the evaporator-crystallizer, is fed to the secondary device 20 and the variable control unit 21 to the chamber. A pneumatic signal corresponding to the specified vacuum value in the apparatus is supplied to the reference chamber located in the secondary

device 20. Depending on the values of the input signals, the control unit 21 processes the command signal to the control valve 22; it changes the steam supply to the ejector until the vacuum in the evaporator-crystallizer is set to the specified value. A pneumatic signal from the output transducer of the rotameter 23, which corresponds to the measured value of water consumption for salt production, is fed to the secondary device 24 and to the variable control unit chamber 25 for recording. The pneumatic signal corresponding to the specified value of the water flow rate in the centrifuge is sent to the setpoint chamber 25. control unit of the secondary device 24. Under the action of the command signal of the regulating unit 25, the control valve 26 is moved until the water flow for salt washing is equal to th. The electrical signal from the pH meter measuring transducer 27, proportional to the measured pH value of the distilled solution, is fed to the secondary device 28 for recording and comparison with a predetermined value set by the local manual setting unit. The set pH value corresponds to the required acidity of the otfugovanny solution. Depending on the difference between the measured and the set pH values, the pneumatic control device integrated in the secondary device 28 acts on the control valve 29. It moves to

as long as the mismatch becomes 0, i.e. until the acidity of the otfugovannogo solution is not established in the required value. This will maintain the acidity of the crystalline ammonium sulfate at a given value.

Using the proposed method of automatic control of the operation of the evaporator-crystallizer will eliminate the production of ammonium sulfate with an acidity above the limiting value for the desired grade of the finished product,

set by GOST.

The automatic system for stabilizing the acidity of an otfugovannogo solution provides a return directly to the evaporation of the maximum possible, based on the restriction of acidity

crystalline ammonium sulfate, the amount otfugovannogo solution. The concentration of ammonium sulfate in the initial solution is maximum.

Thus, along with an increase in quality

of the obtained product, when using the proposed method, the specific costs of heating steam for evaporation of the initial solution are also reduced.

Claims (1)

Invention Formula The method of automatic control of the operation of the evaporator of the L-crystallizer according to aut.St. No. 428758, is different from the fact that, in order to increase the quality of ammonium sulfate 60 and reduce the energy consumption for evaporation of the solution, the water consumption for washing crystalline ammonium sulfate is changed by changing its supply to the centrifuge and acidity of otfugovannogo solution by changing its quantity returned directly to the evaporator-crystallizer.