How to regulate the capacity of vacuum unit in freezing monotone process
In the process of freezing monotony, the commonly used vacuum equipment is the vacuum unit, the vacuum degree of this process will be particularly high, and the extracted gas contains water vapor or condensable gas, so it is suitable for roots water ring vacuum unit.
In the process of careful application, the total pressure in the monotonous box directly affects the heat exchange of the product and the water vapor mass conversion to the condenser, so it is necessary to accurately control and measure.
By reducing the vacuum pump pumping capacity or closing the vacuum pump, the sublimated non-condensate gas is gradually gathered in the cold trap, and the condensation rate of the cold trap is reduced, so as to improve the pressure of the cold trap and the monograph box. This method can improve the total pressure in the tank, improve the heat transfer conditions and the allowable temperature of sublimation interface, and at the same time temporarily shut down the pump can reduce the operating cost. The main defect is that the measurement error of the conductive vacuum gauge is large, which may lead to uneven freezing of the cold trap, and thus constitute a blocking at the inlet.
Two-stage vacuum pump unit (Roots vacuum pump + water ring vacuum pump)
The main pump of vacuum pump unit as the roots vacuum pump, water ring vacuum pumps as backing pump, in order to guarantee the normal operation of the pump, should operate according to the following procedure:
1. Check the integrity of the equipment before installation, and be familiar with the operating instructions of each pump.
2. Fix the base Angle of the vacuum unit in place and connect the pipeline as required.
Note: When connecting the intake pipe, 20-40 purpose filter screen should be installed in the pipeline above the unit to prevent foreign matters such as welding slag from entering the vacuum unit. The pipeline can be removed after passing the suction test and the test run is successful. Ability to install Y-type filters.
3. Before starting the unit, check whether there is leakage in all pipelines of the system; Before the start of the liquid ring pump, the car should be started to check whether it is stuck;
4. Assemble the control cabinet and connect the electric motor and the electric contact vacuum meter according to the electrical schematic diagram.
5. To the electronic control cabinet before sending, telemetry ≮ 10 m Ω its insulation resistance, and the frame and the motor have good grounding; Before starting the unit, check whether the rotation direction of each pump is correct and make other preparations before starting the unit.
6. Adjust the lower limit of vacuum degree on the electric contact vacuum gauge to -0.092mpa and the upper limit to the maximum; Note: When adjusting the upper and lower limits of the electric contact vacuum gauge, the main power must be cut off first to prevent electric shock!
7. During operation, if the vacuum degree of some factor is lower than the limit value, roots pump will automatically stop operation. When the vacuum degree returns to the limit value, roots pump will restart;
8. To turn it off before, want to shut down the system and the unit connection butterfly valve, and then press the stop button, stop running vacuum unit