Pressure control in vacuum distillation
Thread Content
How is the pressure controlled in a vacuum distillation tower? Is there anyone who can explain this? Thank you!
How is it controlled? Isn’t it controlled based on the pumping rate of the vacuum pump?
I don’t know what the control scheme is; is there a PFD diagram available for reference?
Are you using an electric vacuum pump or a vacuum pump with some other type of drive? Regulation of electric vacuum pumps: frequency conversion regulation, backflow regulation, or exhaust pressure regulation. Regulation of other types of vacuum pumps: backflow regulation or exhaust pressure regulation
Use a steam ejector, or a vacuum pump
Our system uses an electric vacuum pump that is connected to the top of the reflux tank; basically, the vacuum pump is turned on at the time of startup, and there’s no need to keep it running afterward
In these cases, the amount of non-condensable gas is roughly calculated based on your materials and condensation temperature; thereafter, a vacuum pump with an appropriate exhaust capacity is selected to ensure that the desired vacuum level is achieved. Domestic water ring pumps are not very reliable as they exhibit significant fluctuations in performance, while imported pumps perform much better.
Okay, thank you. If there is no non-condensable gas, how is it calculated when all the gas at the top of the tower is condensed?
Prepare a high-vacuum tank and a low-vacuum tank; use a vacuum pump to create a high vacuum in the high-vacuum tank. The pressure in the high-vacuum tank represents the absolute pressure, while the pressure in the low-vacuum tank is the system pressure that needs to be controlled, for example, 200 mmHg. A DCS system is then used for control – when the pressure in the low-vacuum tank rises above 202 mmHg, a solenoid valve is activated, allowing the high-vacuum tank to draw air out of the low-vacuum tank until its pressure stabilizes at 200 mmHg.