For large air separation equipment, the generally allowable temperature difference at the hot end is 2-3 ℃; For small medium pressure air separation equipment, the allowable temperature difference is 5-7 ℃.
In actual operation, the heat transfer area of the heat exchanger has been fixed. If the temperature difference at the hot end increases, it indicates that the cooling capacity of the backflow gas has not been fully recovered in the heat exchanger. This may be due to a decrease in the heat transfer performance of the heat exchanger, which reduces the amount of heat that can be transferred under the same heat transfer area; It may also be caused by changes in air flow rate and air flow temperature.
The main reason for the decrease in heat transfer performance of the main heat exchanger in the molecular sieve adsorption process is the improper operation of the adsorber. Due to water entering the molecular sieve adsorber or being impacted by air flow, the molecular sieve pulverizes, bringing powder into the heat exchanger and adhering to the surface of the heat exchanger channel, affecting heat transfer performance, resulting in an increase in the temperature difference at the hot end. In addition, when the adsorber does not clean up the moisture and carbon dioxide in the air and enters the heat exchanger, it will freeze on the heat transfer surface, reducing the heat transfer coefficient and reducing the heat transfer ability. This situation is often accompanied by an increase in the resistance of the heat exchanger.
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