The load regulation range of low pressure air separation unit is related to the regulating performance of feed air compressor, the regulating performance of expander and the structural characteristics of distillation column. At present, the flow regulation range of turbine air compressor with inlet guide vane is 75% to 100%, and that of turbocharged expander with adjustable nozzle is 65% to 100%. Next, the most important thing is to adjust the residual of the distillation column. At present, the load regulation range of distillation column with structured packing can reach 50% - 100%, while that of traditional sieve tray column is 70% - 100%. If the load is too low, it will cause liquid leakage because the speed of steam passing through the sieve is too slow.
When oxygen is sufficient and the oxygen output needs to be reduced, first reduce the output of oxygen products, then reduce the air flow accordingly, and adjust the expansion air volume according to the main cooling level. The liquid gas and liquid nitrogen control valves sent to the upper tower should also be closed according to the distillation conditions. It should be noted that the whole operation should be completed slowly and gradually, so as to keep the distillation conditions stable during the reduction process.
If there is a liquid oxygen storage system, reducing the oxygen production can increase the production of liquid oxygen and make the storage of liquid oxygen more convenient. The oxygen output can be reduced first, then the expansion air volume can be increased, and the liquid oxygen extraction amount can be increased under the condition of keeping the main cooling liquid level unchanged. In order to maintain the stability of upper column distillation, some expansion air can be bypassed if necessary.
