The essence of external icing of air separation incubator is the leakage of local cooling capacity of the tank, and the water vapor in the external air condenses and freezes when it is cold. The main reasons are divided into five categories:
The box seal fails. The sealing gaskets of manholes, manholes and pipeline through plate interfaces are aging, bolts are loose, the box shell welds are cracked, and the external high humidity air continues to penetrate into the box. The moisture is cooled after contacting the low-temperature insulation material, and the cooling capacity is transmitted to the outer wall, and the water vapor is directly condensed and frozen.
The performance of insulation layer is deteriorated. The pearlite insulation material in the box is damped, hardened or insufficiently filled, and the insulation capacity is greatly reduced. The cold capacity of the low-temperature pipeline quickly penetrates the insulation layer and is transferred to the box shell; At the same time, there are holes in the insulation layer, forming a local cold bridge, causing freezing at fixed points on the outer wall.
Internal low temperature medium leakage. The low-temperature liquid oxygen, liquid nitrogen and the welds and valves of low-temperature process pipes in the box are damaged, and the low-temperature medium or cold air leaks out, which directly cools the steel plate of the box, causing rapid icing on the outer wall. This kind of icing is generally concentrated in scope and has a large ice thickness.
The gas seal system inside the box is abnormal. The dry nitrogen gas seal pressure of the incubator is insufficient, and the gas seal pipeline is blocked, which cannot isolate the invasion of external wet air; Negative pressure fluctuation of equipment operation further aggravates moisture backflow and accelerates frost and ice formation on the outer wall.
Impact of environmental conditions. In rainy season, high humidity and low temperature environment, the air moisture content is high, and the cold and heat exchange is intensified; Excessive temperature difference between day and night will also aggravate the condensation and freezing phenomenon on the outer wall of the box.
