In the precooling system of air separation unit, the working temperature should be in specific range, the molecular sieve can work normally. When it is beyond the range of 8-15°, the load will increase, the adsorption effect will reduce and even the adsorption effect lose .
If the precooling system fails, air enters the adsorber of molecular sieve, the working temperature is beyond the normal range, the saturated water content in the air increases, and it operates according to the original set adsorption cycle. In the later stage of the adsorption period, a large amount of carbon dioxide will not be removed, and it will be brought into the main heat exchanger and distillation column, which will block the main heat exchanger and liquefizer, and the resistance of the distillation column will be blocked up. In case of serious, it must stop running and re warm up. The argon production will be stopped immediately once the refrigerator stops running with the device of hydrogenation to produce argon.
Therefore, when the air separation unit precooling unit fails, some measures are taken to keep the air separation unit in operation in a short period, (1) reduce the air volume appropriately to reduce the load of the adsorber; (2) shorten the adsorption period to ensure the work within the allowable range of adsorption capacity; (3) pay attention to monitoring the carbon dioxide content in the air at the outlet of the adsorber below 1 *10-6. (4) The nitrogen flow rate of the product shall be reduced properly, and the nitrogen flow of the decontamination nitrogen cooling column shall be increased to reduce the temperature of the cooling water as much as possible, and the flow rate of the common cooling water shall be increased.
