Design specifications for pressure piping for large air separation unit

The principle of expander with motor brake in air separation plant is to control the speed of expander by braking torque generated by motor generator braking state. Once the brake motor fails, the expander speed will lose control and overspeed will occur. At this time, it is necessary to automatically open the protection and control system. The principle is that the speed measuring motor will send out the overspeed signal to cut off the three-way solenoid valve. The three-way solenoid valve directly controls the air open pneumatic butterfly valve at the inlet of the expander, so that the butterfly valve is quickly closed and the air inlet is cut off. At the same time, the rotation of the valve rod touches the stop and limit switch, so that the power supply of the expander motor is cut off and the safe shutdown is realized.

The liquid oxygen from the main condensing evaporator is compressed by the internal compressed oxygen pump, evaporated and reheated into the main heat exchanger and then out of the cold box as oxygen product. The low-pressure nitrogen is pumped out from the top of the low-pressure tower, and its cooling capacity is transferred to the reflux liquid in the subcooler, which is sent out of the cold box through the main heat exchanger, partially compressed by the first stage of the nitrogen make-up c...