Air separation system's liquid pump system

Air separation unit's liquid pump system

The horizontal pump is horizontally arranged (the liquid inlet pipe is lower than the liquid discharge pipe), and heating gas (set behind the pump or in front of the filter in front of the pump to prevent impurities from entering), seal gas, liquid discharge exhaust valve (discharge at low place and exhaust at high place) and return pipeline (return liquid inlet phase) are required. The rotating speed of the horizontal pump should not be too high. Generally, the discharge pressure is less than 30barg. The horizontal pump has a good bearing capacity for cold contraction due to its horizontal arrangement, However, the dynamic balance of high speed rotor is not satisfied.

The vertical pump adopts the bearing suspension arrangement (the liquid inlet pipe is higher than the liquid discharge pipe), which bears a large downward tension, the center of gravity of the rotor coincides with the shaft, and the speed can be very high; Generally, it is more than 30bar, and it needs to be set: air return in front of the pump (note that there is no horizontal pump), heated air (set in front of the pump filter, air intake at high altitude), seal gas, liquid discharge and exhaust valve (liquid discharge at low altitude, air exhaust at high altitude, and check whether it is cold thoroughly during precooling) and return pipeline (return liquid inlet phase). Vertical pumps are generally multi-stage, and the air return pipeline shall not be downward (flat or inclined upward), otherwise the gas will not be discharged, which is easy to cause pump cavitation. In addition, the motor of the cryogenic pump needs to be equipped with a blowing pipeline to prevent overheating in summer and frosting in winter.

The liquid oxygen pump and the liquid nitrogen pump are on-line cold standby, in which the sealing gas pressure of the liquid nitrogen pump is more than 7barg; The sealing air pressure of the oxygen pump is 4barg (the pressure of the lower tower can be met by nitrogen); Circulating liquid argon pump, one for use and one for standby, the sealing gas is generally sealed by liquid argon vaporization, and the flow is required to have a margin of 20%. Generally, the return valve pressure bypass control and the outlet valve flow level control of the liquid argon pump adopt dual loop control.