During the normal operation of the air separation plant, the temperature of each part of the cold box should be kept in balance. However, due to the temperature difference at the hot end of the heat exchanger and the possibility of no heat transfer between the cold box and the environment, and some large-scale air separation plants may produce a small amount of liquid products, which will cause heat loss. Therefore, to supplement the lost cooling capacity through expander and throttling, we paid electric energy to get the cooling capacity of expander. Why can throttling produce cooling capacity? This is because the pressure decreases after throttling, and the throttled liquid air and liquid nitrogen are saturated liquid. The pressure drop naturally causes the saturation temperature to decrease. In order to maintain its saturation state, part of the liquid is gasified to absorb heat.
