How to resolve high differential pressure issue in FCC amine absorber?Dec-2021
THIYAGARAJAN KUPPUSWAMY, ADNOC, KTHIYAGARAJAN@ADNOC.AE
FCC amine absorber higher DP and carryover is an usual phenomenon for all refineries and this is predominantly due to the iron sulphide and cyanides coming out of solution in rich amine solution. This creates foaming inside the interstage column whereas does not occur in other amine absorbers or amine regenerators. Some iron salts are very soluble in lean amine an hence hard to filter out or observe. Usually hardware issues will not be the case if the DP is progressive over a period of time.
The solution to this problem is to perform online hot water wash with a proprietary chemical until the wash water is clear (initially black to grey to water white). This washes out the deposited ironsulfides and cyanides that are on trays. During this time, the interstage amine absorber has to be bypassed if it is allowed or shutdown for few shifts to perform this.
Mahesh Harge, Tecnicas Reunidas, firstname.lastname@example.org
2 possible reasons which I see are:
1. Heat Stable Salts - Test your amine
2. Foaming - Check the amine carry over.
Proper root cause to be identified for the increased pressure drop across tower which has lowered the liquid capacity resulting in off spec gas.
Doug Morgan, Searles Valley Minerals, email@example.com
I doubt the words "heat stable salts" would have entered our vernacular if it had not been to the misapplication of low pressures / temepratures to amine regeneration. There is no reason the regernerator (stripper) has to operate at low pressure / temperature on systems that absorb at low pressures (EG: FCC, Carbon Capture from flue gas). Of course most people just assume that stripping at low pressures somehow enhances something. To be sure, it enhances CAPEX by increasing dimaters and heat stable salt accumulation.
Chris Wallace, Filtration Technology Corporation (FTC), firstname.lastname@example.org
Have you done any thermal imaging of your absorber tower? How healthy is your amine? Specifically suspended solids and hydrocarbons? Have you checked the TSS levels of your amine? You could be fouling the trays with suspended solids. If you have high suspended solids, I suggest taking a closer look at your level of filtration.
Milap Sheth, SATORP, Milap.Sheth@satorp.com
Amine absorber is seive tray tower. WE observed high DP in last few months and lean amine flow could not be increased above min flow due to carry over of amine to knock out pot. H2S in fuel gas is remaining on higher side. Column might have fouled with heat sensitive salts.
Aadam Aryan, Distillation Equipment Company Ltd, email@example.com
Solution will depend on the type of internals you have in the amine absorber. Please provide further details.