From which location is it best to introduce nitrogen for purging during the shutdown of an ethylene plant?
Thread Content
This post was last edited by yanran88 on 2011-7-26 at 12:25. During the major overhauls of ethylene plants, it is very difficult to purge systems such as those used in propylene and ethylene units, as it’s hard to empty them completely. I was wondering if there are any good methods to address this issue. When maintaining and purging equipment pipelines, are there any particular considerations or requirements regarding the introduction of nitrogen, such as introducing it at higher points and discharging it at lower points?
When introducing nitrogen, moisture and impurities should be removed first; it is best to introduce it at a higher point and discharge it at a lower point, using purging from high to low to ensure thorough cleaning.
The difficulty in purging the refrigerant systems of propylene and ethylene plants after maintenance shutdowns lies in the fact that these systems operate at low temperatures, making it hard to achieve a dry and clean state. It is best to keep the cracking gas compressor running after both cryogenic compressors are shut down, so as to \"reheat\" the system; this way, the temperatures in the cryogenic tanks and the two refrigerant systems rise, thereby facilitating the purification process.
The suggestion from upstairs is good, but it should be operated with nitrogen; using pyrolysis gas isn’t feasible as the losses would be too high.
Just purge with hot nitrogen; this is faster