Heating and thawing of air separation unit
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Dear seniors in the air separation field, our company’s air separation unit has been in operation for two years. This time, as part of the preparation for heating, thawing, and purging due to a prolonged shutdown, I would like to ask whether there is a risk of pipes breaking as a result of stress changes or thermal expansion and contraction Are there any good methods for blowing it out?
If there is concern about leaks, can pressure testing be carried out to ensure airtightness? Personal opinions, learn together
Currently, the liquid-air level in the fractionation tower is 0, and the liquid oxygen level in the main cooler is 4750 mm. If evacuation is carried out, should the liquid oxygen be drained immediately, or allowed to vaporize naturally?
First, drain it out and then heat it for evacuation; otherwise, the liquid will vaporize too rapidly
Pipeline stress and thermal expansion and contraction are inevitable, so it is necessary to proceed slowly and increase the temperature gradually. As for the pipes breaking due to expansion when the temperature rises, this is highly unlikely, unless there are problems with the pipe supports over the 2 years of operation, or if something prevents the pipes from expanding. After all, the current cold state also results from the hot state while driving, doesn’t it?
Follow the manufacturer’s instructions – that usually won’t go wrong. Is it from Hangyang? Hangyang’s instructions are quite detailed
Before heating, all the liquid in the tower must be drained; it is advisable to let it sit for a few hours before starting the heating process, in order to prevent the liquid from vaporizing when gas is introduced and causing damage to the equipment.
It is necessary to drain the liquid before heating it up significantly. If possible, it is best to let it sit for a while before introducing air for heating; however, the heating rate should be controlled, not exceeding 15 degrees per hour, to prevent the pipes inside the cold box from cracking~~
First, allow proper drainage and let it stand; then use heated air while controlling the rate of heating. Generally, by controlling the total amount of air or the rate of temperature increase and following the established procedures, there should be no problems