When the air separation plant stops, the liquid on the air separation tower will flow into the condensing evaporator to raise the liquid oxygen level. If the liquid oxygen surface is full of oxygen outlet tubes, the liquid oxygen will flow into the Plate-fin Heat Exchanger, which will lower the temperature of the heat exchanger. When restarting, the high pressure air temperature will drop (T2 =-180 ~ -190℃), the temperature before the expansion machine will also drop to-160℃. If the expansion machine is started immediately, liquid will be brought into the expansion machine, causing damage to the expansion machine.
Therefore, if the temperature of T2 and T3 is too low after the temporary stop, the section-1 valve can be opened first to make high pressure air enter the Plate-fin Heat Exchanger, first, make the liquid in the heat exchanger gasification, and the temperature rises, and promote the temperature rise before the expansion machine. When the temperature of T1 is higher than-150℃, start the expansion machine again. Open the bearing gas and sealing gas, and adjust the pressure to 0.5 ~ 0.6MPa, then fully open the air vent valve of the expansion machine, and then slowly open the air inlet valve to gradually increase the pressure. Control the rotating speed of the expansion machine to be about 105r/min, and then adjust the sealing air pressure to make it about 0.05MPa higher than the exhaust pressure.
After the expansion machine operates normally, adjust the working condition of the air separation Tower until the equipment is in stable production.
