The refrigerating capacity of an air separation unit is composed of two parts: expansion mechanism refrigeration and system throttling effect refrigeration. These two components work together to ensure the low-temperature cyclic operation of the device.
Throttling effect is the fundamental refrigeration method of air separation systems, and not only throttling valves can produce throttling refrigeration. According to the principle of gas expansion refrigeration, the process of all high-pressure gases in the device flowing towards low-pressure areas and expanding freely will result in temperature reduction and the release of cold. Throttling valves are just the most typical and concentrated throttling and depressurizing components. The gas pressure drop processes in system pipelines, heat exchangers, and structured flow channels all accompany a weak throttling refrigeration effect, becoming an important supplement to the system's cold capacity.
As a core refrigeration device, the expansion machine's refrigeration process does not exist independently. It also encompasses the fundamental refrigeration function of throttling expansion. The expansion machine achieves efficient pressure reduction and expansion of gas through the work done by the impeller. While reducing the internal energy of the gas and producing a large amount of effective cooling capacity, it also covers the throttling refrigeration effect of conventional pressure reduction expansion. Compared to ordinary throttling processes, the expansion machine can recover the energy from gas expansion, achieving higher refrigeration efficiency and serving as the main source of cooling capacity for the device.
The refrigeration system of the air separation equipment combines high-efficiency expander refrigeration with global throttling refrigeration. The cooling capacity generated by the pressure reduction and expansion of the global gas is superimposed, jointly maintaining stable operating conditions for low-temperature distillation and gas liquefaction of the equipment.
