DEAR Air separation plant.In the start-up stage of the air separation unit, the temperature of the switching heat exchanger decreases with time, and the temperature difference of the positive backflow gas flowing through the channel is far greater than the measured temperature difference of the cold end. Moreover, with the extension of switching time and the acceleration of temperature drop, the self clearing temperature difference of cold end will expand.Then sweep the frost, and do not make the frost melt in the cold insulation box, which will affect the filling of cold insulation materials. After heating to room temperature, air tightness test was carried out. If there is a treatment item, it needs to be naked cold again after treatment. The frequency and qualification standard of naked cooling depends on the specific situation. After the naked cooling is qualified, each adsorber is loaded with adsorbent, and the cold insulation box is loaded with cold insulation material.DEAR Air separation plant.The clearance between the valve stem and the valve seat hole is too small, and it will be stuck at low temperature. When it is found that the automatic valve is damaged, it should stop temporarily and heat the valve box separately. When the discharge temperature reaches about 10 ℃, maintenance can be carried out. If there is a shortage of automatic valve parts in the box, try to blow them back.
DEAR Air separation plant.During the start-up of the low-pressure oxygen generator, the self-cleaning condition of the switching heat exchanger has not been established, so some water or carbon dioxide must pass through the expander. If the temperature decreases after expansion, it may precipitate in the expander and cause blockage of the expander.In case of temperature deviation in the middle part, it should be adjusted as soon as possible. Because when the deviation is small, as long as a little adjustment, it will soon return to normal. If the deviation develops to a large extent and measures are taken, the adjustment will become difficult. In the process of adjustment, a small number of times should be taken, that is, the amount of each adjustment should be less, but the number of times can be more, so that the middle temperature tends to be uniform smoothly. In the process of regulation to prevent irritability, so as not to produce new interference factors.Close the oxygen regulating butterfly valve and fully open the dirty nitrogen and pure nitrogen regulating butterfly valve. Turn off steam source of steam heater. Cut off the power switch of electrical equipment and make it in the start position. After finding out the cause of the power failure and eliminating the fault, make preparations for the start-up.
）The enrichment of argon in the upper column is not constant. When the purity of oxygen and nitrogen products changes, the distribution of argon in the upper column will change, and the composition of argon fraction will also change. The change of oxygen purity is more sensitive to the composition of argon fraction. When the oxygen purity changes by 0.1%, the argon content of argon fraction will change by 0.8% ~ 1%. With the increase of oxygen purity, the argon rich region will move up and the argon content of the fraction will decrease.When the power supply of the air separation unit in the molecular sieve adsorption purification process is restored after the power failure, the operation should be carried out according to the following steps: the possible impact on the air compressor and other mechanical equipment should be judged in case of sudden power failure. If there is no influence, start the air compressor according to the operating procedures of the air compressor;DEAR Air separation plant.In normal operation, the surface pressure of the main cooling liquid oxygen surface at the bottom of the upper tower is about 0.04MPa, and the evaporation latent heat of oxygen is 6700kj / KMOL; the condensation pressure of gas nitrogen is about 0.48mpa, and the condensation latent heat of nitrogen is 4815kj / KMOL. The latent heat of condensation of nitrogen is less than that of evaporation of oxygen, that is to say, the cooling capacity required to condense 1 mmol of gaseous nitrogen into liquid nitrogen is less than that released by evaporation of 1 mmol of liquid oxygen.
