Is it necessary to install manual shut-off valves at the inlet and outlet of the liquid oxygen pump in the air separation internal compression process?
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To all experts in air separation: In the internal compression process for air separation, in order to facilitate online maintenance of the liquid oxygen pump, and given that control valves are used at both the inlet and outlet of this pump, is it necessary to install manual shut-off valves at those same locations? If setting it is necessary, after installing a manual shut-off valve, due to the large pressure difference before and after the valve, liquid oxygen tends to throttle and vaporize during opening, which poses a risk to safe operation. How should this valve be operated?
Generally, manual shut-off valves should be installed at both the inlet and outlet of liquid oxygen pumps. Under normal circumstances, the manual shut-off valve is in an open state. The shut-off valve closes only during removal and maintenance. It is necessary to check the open status of this cut-off valve before driving.
Normally, the liquid oxygen at the inlet of the oxygen pump has a certain degree of subcooling during normal operation; the pressure is low, so there is no safety risk； The pressure at the pump outlet is relatively high, but the saturation temperature of the medium increases accordingly; as long as proper cooling is provided and the operation is carried out correctly, the safety factor is quite high. (For reference)
There is no need to install manual valves. When it is necessary to shut down the system, first close the control valve, and then turn the handwheel on-site to the fully closed position. However, when starting up the system, remember to open the control valve slightly first; this is done to prevent accidents with the oxygen pump, as the valves can be locked in a closed position to avoid greater losses.