Got 2x aMDEA absorption column's with structured packing removing CO2 receiving exactly the same feed gas. Always have problems with one of the absorbers while the other one never has an issue. Occasionally the dP (based on dP instrument for each bed not individual PTs) across the packing of both the top and bottom bed plummets (reduces by 25-50%) on the troublesome absorber, with no change in gas or amine flow. We then go offspec and have to reduce gas rates by about 20%. Sometime later the dP will recover back to normal and the rates can be increased again. The only other symptom, that is repeatable, is that the temperature on the lean amine inlet and the gas outlet of the absorber inverts when these events occur. Normally the gas outlet temp is cooler than the the lean amine inlet temp (of course there could be minor calibration issues). However when the issue occurs this inverts slightly (gas outlet becomes warmer than lean inlet). It seems to be completely random when these "dP" events occur however we have repeated it by taking off our carbon bed and filtration on the lean amine side for 7 days and we had issues until we brought back the carbon bed a few weeks later after finishing maintenance.
The regeneration system is completely fine (regen temperature is constant) and there is no change in valve opening , levels suggesting there is significant foaming. The quality of the amine (activator, HSS , strength , lean loading, degradation etc) is the same in each unit and the amine is completely clear (like water) when sampled. Use of antifoam (silicon based antifoam) is also the same along with the use of activated carbon and filters (5um filters U/S & D/S of carbon bed slipstream). The troublesome column has been inspected and was literally spotless.
To me the only way the dP can change across the structured packing, at constant gas and liquid flow, is due to a change in density or viscosity of the gas / liquid inside the column. Impact on gas viscosity would be minimal so you would suggest the liquid phase. This would usually suggest the column is foaming or potentially flooding however you would expect the dP to rise in those scenarios hence the confusion.
Edited by kek12345, 10 May 2024 - 02:59 AM.