We usually do not control the bottom level in our primary absorber tower of DCU Gás recovery Section. The bottom of the primary absorber tower goes upward the compressor after cooler thats goes to the high pressure vessell. The gás of the high pressure vessell goes to the primary absorber and the liquid to the deetanizer tower. So, it is possible to send gás mixed with liquid in the stream of the bottom of primary absorber tower, if there is no level in the tower. What is it the risks and the problem with this operation ? Only a gás recirculation ?
The configuration you describe is a common one for gas plants. I think it is common to have only a loop seal to drain liquid out of the primary absorber and prevent vapor back flow. If vapors were to be entrained with the liquid from the primary absorber, they would recycle back to the primary absorber from the high pressure separator. This recycle could increase the vapor load to the primary absorber, if it were excessive.
I do not believe there are any process safety related hazards with loosing the level in the primary absorber. There might be a concern for two-phase flow in that rich oil line so it might vibrate if there was a significant vapor flow through that line.