Cours project by discipline «basic technological processes and devices» content

3. Description of the technological scheme
The scheme of a single-shell evaporator plant is shown in fig. 6.6. The initial diluted solution from the collector 11 is supplied by a centrifugal pump 10 to the heat exchanger 12, where it is heated to a temperature close to the boiling point, and then to the evaporator 9, from which the evaporated solution enters the collector 7. From there, the centrifugal pump 8 is supplied to the consumer. The evaporator and the heat exchanger are heated by hot steam coming from the boiler house.
The vacuum in the evaporator is created due to the condensation of secondary vapors entering the evaporator, when they are cooled with water in a barometric condenser 3 and the condensing gases are sucked off - by a vacuum pump 5. To prevent water drops from entering the vacuum-pass, a trap 2 is installed in front of it. water and condensate is discharged to the condenser by means of a barometric pipe with a hydraulic seal 4. The condensate of the heating vapors and the evaporator and is heat exchanged through condensate traps and sent to the boiler room or for technological needs.
The scheme is automated. The control system of the evaporator plant must ensure the required capacity of the plant at a given concentration of the final product. In conjunction with this, the main adjustable parameters are: 1) the concentration of the finished product; 2) the temperature of the initial solution after the heat exchanger 12 before feeding it to the extractor; 3) level in the evaporator.
Automatic control systems work as follows. With an increase, for example, in the supply of the initial solution, the temperature of the solution after the heat exchanger 12 will decrease, the level of the solution in the vaporizer 9 will increase. To stabilize the temperature of the solution, the temperature controller will give a signal to increase the flow rate of the heating steam and the heat exchanger 12. The evaporated solution flow controller will give a signal, the position of the throttle valve on the pipeline will change in such a way that the solution withdrawal from the evaporator will increase. This can lead to a decrease in the concentration of the stripped off solution. For se stabilization with the help of a concentration regulator, the supply of heating steam to the evaporator will increase
Due to the increase in the supply of the initial solution, the amount of secondary steam entering the barometric condenser 3 will increase. The temperature of the water in the barometric tube will increase, and the vacuum in the system will decrease. In order to stabilize the water temperature in the barometric tube, the temperature controller will increase the return water supply to the barometric condenser to condense the secondary vapor, which will increase the vacuum in the system. To create a deeper vacuum, it is necessary to fully open the valve in front of the vacuum pump or turn on an additional vacuum pump
The automation scheme provides for the stabilization of liquid levels in the tanks. During the brewing process, flow rates, pressures, and temperatures of process flows are controlled using control and measuring devices (CIP)^.