During the cold start of air separation, is it necessary to drain the main cooler and the liquid from the lower column? ? ?
Thread Content
During short-term shutdowns of the air separation unit, the liquid in the main cooler and the lower column is generally not discharged; it is necessary to save time associated with the accumulation of such liquid when restarting the unit. I wonder how long the liquid levels in the main cooler and the lower column generally remain stable after parking the plant? How many days can it be kept cold at most, and which metric is used to determine whether to release it?
With the main cooling liquid level at its highest. There is a possibility of pumping all the liquid from the lower column into the upper column. It is necessary to use the main cooling liquid level as a reference, provided that the levels of harmful elements in the main cooling fluid are not high. As for the number of days, it depends on whether the valve can cool down quickly and on whether the thermal conductivity of the insulation material is good.
One approach is to follow the manufacturer’s instructions strictly: if the machine is shut down for more than 24 hours and the level of the primary coolant is below 800, it’s necessary to drain the liquid. The other approach is to rely on practical experience, striving to maintain the cooling effect and the correct coolant level, while also analyzing the contents of acetylene, hydrocarbons, etc., in the liquid to determine how many days it’s possible to keep the system running. Some people manage to keep it running for 7–8 days, while others manage to do so for over 15 days~~
This time, the shutdown will last 6-8 days; for safety reasons, it has been decided to drain both the main coolant and the liquid in the lower tower. We have online hydrocarbon analyzers.
After 7.19, everyone became more cautious~~ Indeed, safety is the greatest benefit~
Previously at Air Liquide, during a 10-day maintenance period, no liquid was drained, and the hydrocarbon levels were not above the limit； Yima is operating with defects; there are management issues.
Allow a small amount of liquid to drain out while the machine is running; this is done to check whether there are any impurities entering the distillation tower. It’s best to use a white cloth to catch the liquid and examine it. Whether to drain fluid during short pauses depends on the characteristics of one’s own setup; even if drainage is not performed, it is still necessary to allow a small amount of flow through the bottom drain of the distillation column in order to maintain fluid movement and prevent the accumulation of hydrocarbons
Since liquid is being drained, it’s better to just start the engine while it’s warm; otherwise, if some liquid remains in a certain corner and isn’t completely drained, could that lead to problems?