DEAR Cryogenic air separation unit.When the low-pressure oxygen generator starts up, the cooling capacity of the main cooler needs to be consumed, and the cooling capacity required to cool it to the working temperature is also certain. Some people think that gas precooling and liquid air precooling in the second stage and the fourth stage both transfer part of the cooling capacity to the main cooler, and the effect should be the same. Therefore, the precooling of the main cooler is ignored, resulting in the supercooling of the switching heat exchanger in the liquid accumulation stage.According to the weight of different fractionating tower, select appropriate steel wire rope, hang the tower flat on the sleeper, and carry out air tightness test; tie the steel wire rope to the lower part of the upper shell, and pad it with about 10 mm wood around to prevent the shell from deformation, and then lift it to the specified position with crane;DEAR Cryogenic air separation unit.The amount of rising steam in the lower tower and the amount of condensation in the condensing evaporator are reduced, which also has a certain impact on the distillation condition of the tower; after the switching of the cold accumulator (or switching heat exchanger), the backflow sewage nitrogen vaporizes the deposited liquid air due to the reduced pressure.
DEAR Cryogenic air separation unit.In normal operation, the biggest influence on the operation cycle is the temperature difference control of the cold end of the switching heat exchanger. If the temperature is not well controlled, on the one hand, the self-cleaning effect of the switching heat exchanger will be poor, and carbon dioxide will accumulate in the heat exchanger and increase its resistance; on the other hand, a small amount of carbon dioxide will be brought into the tower.When the temperature of the backflow gas out of the accumulator decreases, the temperature difference at the hot end will be larger. The cooling capacity absorbed by positive flow air is more than that absorbed by return flow and positive flow air, so the temperature of air out of the accumulator decreases, resulting in the reduction of temperature difference at the cold end.DEAR Cryogenic air separation unit.Abnormal operation of molecular sieve purification system will shorten the operation cycle of the device. It is mainly caused by the following reasons: short circuit of molecular sieve adsorber bed. In the process of start-up, due to unstable air velocity control or too large pressure difference between the two tanks during switching, the bed will be impacted, resulting in uneven molecular sieve bed and short circuit of bed.
The packing fouling of spray cooling tower not only makes the air out of the tower easy to carry water, but also makes the air out of the tower temperature rise, which is unfavorable to the air separation production. Therefore, the water quality should be improved to make the spray water as clean as possible. In order to prevent scaling, try to reduce the temperature of the air entering the spray tower.Generally, the nitrogen content in the fraction should not be more than 0.01%. In a word, the operation of the crude argon column should gradually increase the load of the crude argon condenser, too fast operation will be counterproductive, making the whole system fluctuate.DEAR Cryogenic air separation unit.A part of liquid oxygen is led out from the bottom of the main condensing evaporator to evaporate in the auxiliary condensing evaporator. With the evaporation of liquid oxygen, acetylene and other explosives are also concentrated. This part of liquid oxygen with high acetylene concentration is led to the acetylene separator, accumulated at the bottom of the separator and regularly discharged. This explosion-proof method has been used in 3350m3 / h air separation unit with high and low pressure process, which can prevent acetylene accumulation in the main condensing evaporator and ensure the safety of the main condensing evaporator.
