To avoid cavitation in centrifugal liquid oxygen pumps during air separation operation and maintenance, it is necessary to strengthen operational standards and reduce factors that can induce cavitation.
Control the temperature and pressure of liquid oxygen. The temperature of liquid oxygen entering the pump should be lower than the vaporization temperature corresponding to the inlet pressure to prevent some liquid from vaporizing and forming bubbles. Raising the pressure of liquid oxygen can increase its gasification temperature, for example, by lowering the installation height of the pump to increase the inlet static pressure head, or by using reverse injection to create a certain static pressure at the liquid oxygen inlet.
To avoid idling and long-term low flow operation, when the liquid oxygen pump is idling, the power consumed by the motor is only used to stir the liquid inside the pump, resulting in an increase in liquid oxygen temperature and gasification. Long term low flow operation will cause fluid circulation in the pump, exacerbating temperature rise. The flow rate should be controlled within a reasonable range through the pump outlet valve, and the use of suction pipeline valves to adjust the flow rate should be avoided.
Promptly deal with gas blockages and leaks. Gas blockages (caused by a large amount of liquid oxygen vaporization blocking the flow channel in the pump) often occur with cavitation and require immediate exhaust until the pump is stopped for treatment. Excessive or insufficient sealing pressure can cause leakage or idling. It is necessary to accurately control the sealing pressure to prevent gas from leaking into the pump inlet through the labyrinth.
In the operation and maintenance of air separation, in order to avoid cavitation of centrifugal liquid oxygen pumps, in addition to strengthening operational standards, comprehensive measures need to be taken from structural design optimization, material and process upgrades.
