SU915869A1 - Method of regulating evaporation process - Google Patents

Description

The invention relates to methods for automatic regulation of evaporation processes and can be used to automate the process of evaporation of solutions and suspensions in the chemical industry, mainly in the production of mineral fertilizers. ^five

A known method of automatic control of the evaporation process, in which by changing the supply of heating steam depending on the pressure in the first apparatus, the pressure is corrected for the consumption of steam and condensate discharged from the first evaporator unit [1].

The disadvantage of this method is that the control system generates a control signal after changing the output parameters.

In the presence of intense disturbances, this leads to undesirable fluctuations in the concentration of the solution at the outlet of the evaporator.

The closest in technical essence to the present invention is a method for automatically controlling the evaporation process in a multi-unit solution installation by changing the density of the heating steam

2

and the total alkalinity of the initial solution and the density of one stripped off solution [2].

The disadvantage of this method is that it does not provide a high quality of the output product due to the lack of regulation of the temperature of the condensate entering the second evaporator. When evaporating thermosensitive solutions, there is a limitation on the maximum temperature, the value of which depends on the density and total alkalinity of the initial solution. To speed up the process, it is necessary to maintain the optimum temperature in the second evaporator.

The purpose of the invention is to increase the efficiency of the evaporator and improve the quality of the output product.

This goal is achieved by the fact that in the Method of regulating the evaporation process additionally measure the temperature of the condensate entering the second building, and regulate it with a correction for the density and total alkalinity of the initial solution and the density of the saved solution.

3 915869

The drawing shows a diagram of the implementation of the method of automatic control of the evaporation process.

The evaporation process takes place in a three-unit vacuum evaporation unit with an additional ₅ evaporators containing evaporators.

1-3, pre-evaporator 4, collection 5 of one stripped off pulp, shell-and-tube vacuum condenser 6, hydraulic tank 7 and plate heat exchanger 8., ₀

The control loop for the ratio of the heating steam consumption to the initial solution contains sensors 9 and 10 of the flow rate and a secondary device with an integrated regulator 11, a density sensor 12, a sensor 13 for the total alkalinity of the initial _<5 solution and a valve 14.

The coirtool for controlling the temperature of the condensate at the outlet of the plate heat exchanger contains a temperature sensor 15, a secondary device with an integrated regulator 16, a density sensor ₂ θ 17 and a valve 18. A signal from the sensors 12 and 13 is supplied to the same circuit.

The method is as follows.

The initial solution is fed into the separator of the evaporator 1, the partially evaporated solution ₂ $ enters the next evaporator 2 and from there into the evaporator 3. The evaporated solution from the evaporator 3 enters the evaporator 4. The evaporated solution from the evaporator 4 is directed by gravity into the collection 30

nick 5.

The heating steam is supplied to the heating chamber of the pre-evaporator 4 and the evaporator 3. The resulting juice vapor when the solution boils in the separators of the pre-evaporator 4 and the evaporator 3 is supplied to the heating chamber of the evaporator 2. The steam of the evaporator 2 enters the annular shell-and-tube vacuum condenser 6, where it is cooled and condensed on the cold surface of the tubes through which water flows. ^, °

The condensate of the juice vapor of the evaporator 1 from the condenser 6 flows into the hydraulic lock tank 7, from it into the plate heat exchanger 8, where the heating steam condenser of the evaporator 4 and the evaporator 3 is heated and used for heating the evaporator 2.

 In the automatic control system, the value of the ratio of the costs of heating steam and

four

of the initial solution, measured by sensors 9 and 10, and measured by a secondary device with a built-in regulator. Some give a regulating signal to the valve 14. Density and total alkalinity corrections of the initial solution from sensors 12 and 13 are also introduced to the controller 11.

The condensate temperature at the outlet of the plate heat exchanger is measured by the temperature sensor 15 and is fed to a secondary device with an integrated regulator 16, which also introduces corrections for the density and total alkalinity of the initial solution and for the evaporated solution density at the outlet of pre-evaporator 4 measured by sensors 12, 13 and 17 The regulating signal of the regulator 16 controls the valve 18 installed in the cold condensate line to the plate heat exchanger 8.

The proposed method allows you to control the concentration of the output solution and reduce the fluctuation of the density of the solution at the outlet of the evaporator by 70%. The estimated economic effect from the introduction of the method by increasing the efficiency of the evaporator and improving the quality of the output product is 20 thousand rubles. in year.

Claims (1)

Claim The method of regulating the evaporation process in a multi-unit installation by changing the supply of heating steam depending on the density and total alkalinity of the initial solution, and the evaporated solution density, characterized in that, in order to increase the efficiency of the evaporator and. quality of the output product by improving the accuracy of regulation, additionally measure the temperature of the condensate entering the second building, and adjust it with a correction for the density and total alkalinity of the initial solution and the density of the evaporated solution.