Why should the air separation equipment be defrosted?

Long running time, coupled with multiple starts and stops, some parts of it will be frozen by moisture. In this case, the heat exchange effect will be worse, the resistance will increase, which will reduce the output and increase the energy consumption, so thorough Warm up and remove moisture.

The difference between gas air separation and liquid air separation is that the product coming out of the cold box is gaseous or liquid, and the product coming out is gaseous, which is called gaseous air separation; the product coming out is liquid, which is called liquid air separation.
Liquid air separation has one more heat exchanger (condenser) than gaseous air separation. After the product comes out of the refinery tower, it exchanges heat with a certain medium (sewage nitrogen) through this condenser, recovers the cold energy, and makes it further liquefied.
If all the equipment is operating normally, it should produce pure oxygen products or nitrogen products.
If the output is to be affected, either the gas purity is not good enough, or there is a problem with the storage pressure vessel.

There is a close relationship between the distribution of the amount of liquid air and the amount of liquid nitrogen in the lower tower and the purity of the liquid air and liquid nitrogen to be maintained. In other words, the distribution of liquid air and liquid nitrogen determines the purity of liquid air and liquid nitrogen.
The liquid air throttle valve only controls the liquid air level, and the liquid nitrogen throttle valve can control the purity of the liquid nitrogen and also affect the purity of the liquid air. Opening the liquid nitrogen throttle valve reduces the reflux ratio of the lower tower due to the decrease of the reflux liquid of the lower tower, the purity of the liquid nitrogen decreases, and the purity of the liquid air (oxygen content) increases.
The two valves restrict each other. In an air separation plant, there are many such valves that need to be coordinated with each other. A good debugging result has a lot to do with the final purity of your product, that is, the output.
In addition, when the pressure vessel storage tank stores your products, if there is too much gasification, the pressure of your pressure vessel will be high, and the pressure will often be relieved, which is equivalent to reducing your oxygen and nitrogen output.