How to purge the gas separation unit

Place the torch first, then purge with nitrogen.

The nitrogen purging time is long, and certain areas are difficult to purge; moreover, some C4 components tend to vaporize and cause low temperatures after being purged with nitrogen. . . Of course, having an abundant supply of nitrogen at high pressure is one thing; however, it’s not good to pump large amounts of nitrogen into the gas system. Steam cleaning is much better. We supply steam at the bottom of the tower, and let the gas escape from the reflux tank. Once the line through which the gas escapes from the reflux tank becomes hot, we open the vent on that tank to check whether steam is present; if steam is detected, we then switch to using the on-site vent. . The concern with such equipment is that the double-flange diaphragm box might get damaged; some magnetic float level gauges cannot operate at high temperatures. It is necessary to close the upstream and downstream valves, and only slightly open them towards the end of the purging process in order to carry out a brief purge. What other devices are sensitive to high temperatures? The floating head of the heat exchanger? Am I worried that thermal expansion and contraction will cause leaks? It’s possible, but since you used steam for purging, it must have been overhauled. What is there to fear?

Because steam purging is still required before starting up

Before starting up, it is also possible to use nitrogen to displace air; however, non-condensable gases must be vented during startup, and the presence of nitrogen inside the system makes operations difficult at the beginning. Use steam to displace air; once steam is visible in all areas, it can be turned off after a few minutes, and then gas can be used to fill the space. If you are worried that prolonged purging of the small floating head with an aftercooler might cause problems, you can pass through the cross-connected line while removing air, and then simply go through the heat exchanger at the end.