What determines the temperature setting of the oxygen produced by air separation? What are the hazards if it is too low? What are the hazards if it is too high?

The oxygen outlet temperature is too low, resulting in excessive heat loss; the expander is of a large capacity； It’s too high; the load on the main heat exchanger is large, resulting in high operational costs. Taking into account both equipment costs and operating expenses, the temperature is set around 12 to 20 degrees Celsius.

I don’t know whether you use internal compression or external compression; I’ve never worked with internal compression, so let me explain our external compression method. The oxygen produced is transported through stainless steel pipes. LZ chooses stainless steel probably to account for the impact of low temperatures on its toughness. This issue is hardly a concern in air separation processes, as the temperature of the oxygen produced there is determined with regard to maximizing heat utilization while also taking into account the capacity of the expansion machine, thereby ensuring that liquefaction occurs during the cooling process in the expansion machine. Under normal conditions, the temperature of the produced gas can be adjusted through suction at the middle and bottom of the expander. The operation of the purification molecular sieve also causes periodic fluctuations in the oxygen temperature. In addition, if the oxygen temperature is too high, it is necessary to pay attention to the inlet and outlet temperatures at the expansion end of the expander; this may be caused by insufficient suction at the middle and excessive suction at the bottom, which can result in the temperature becoming too low during air expansion and leading to liquefaction that damages the expander’s impellers. Too low a temperature indicates incomplete heat exchange; it is also caused by improper adjustment of the middle and bottom extraction systems, which leads to an excessively high outlet temperature of the expander. Insufficient cooling capacity makes it difficult to accumulate liquid, and the purity of the produced gas is not adequate. The temperature at which oxygen is produced is adjusted gradually once the equipment is operating properly; one can pay attention to this during the start-up and shutdown of the LZ

It is generally determined based on the temperature of the air entering the plate-fin heat exchanger. The temperature difference at the hot side is generally set at 3 degrees, so the outlet temperature of the cold fluid is usually about 3 degrees lower than the inlet temperature of the air.