In the switching heat exchanger, moisture and carbon dioxide cannot be completely and thoroughly removed. Although the remaining amount is very small, it will gradually block the switching heat exchanger over time. In the production, it shows that the resistance of switching heat exchanger increases continuously, the free section of gas flow decreases, and the air volume cannot enter. In addition, in the cold section of the switching heat exchanger, carbon dioxide has been basically cleaned up theoretically, but due to the clamping effect of air flow, the amount of carbon dioxide brought into the tower is much more than the theoretical content. Apart from being partially cleared by the adsorption filter, the rest of the carbon dioxide will gradually accumulate in the tower and block the tower plates, pipelines and valves. In addition, the air also contains a small amount of acetylene and hydrocarbon. Although adsorbed by acetylene adsorber, its adsorption efficiency can only reach about 97%, and the rest part will also threaten the safe production of the air separation plant. In order to eliminate these accumulated impurities such as water, carbon dioxide, acetylene, etc., when the air separation plant runs for a certain period of time, it needs to be stopped for heating and blowing off.
In addition, during the operation of the air separation plant, it is necessary to heat and blow it off in order to eliminate the low temperature before it is forced to stop for maintenance due to the malfunction of the equipment or machine. Before all the installation of the air separation plant is completed and the commissioning is started, in order to remove the remaining impurities and moisture in the equipment, heating and blowing operations are also needed.
As for the equipment (such as liquid-air adsorber) used for monomer replacement, when the silica gel is saturated by acetylene and carbon dioxide, in order to recover its adsorption capacity, heat and regenerate it regularly. When the expansion filter and expansion machine are frozen by carbon dioxide, in order to thaw, monomer heating operation is also needed.
