Q & A > Question Details
I would like to know the configuration of an amine system for refineries having multiple hydroprocessing units with multiple ARU / SRU.

Are common lean amine and common rich amine pipelines connecting all units, or is each hydroprocessing unit independently assigned to an exclusive ARU / SRU unit (with rich amine and lean amine pipelines running between these two units, oor is one hydroprocessing unit i connected to two ARU / SRU units for flexibility in operation?

Kindly share your views stating the pros and cons of each configuration. You may share specific experience from your own refinery on the reliability of units having any one of the above.
27/05/2020 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
One would normally have multiple units feeding a single ARU using common collection and distribution systems. Having a dedicated ARU for each unit would add a lot of unnecessary equipment, which would increase both the capital and operating/maintenance cost.

If all the refinery contactors utilize a common collection and distribution system, then any problems such as hydrocarbon contamination from one contactor can propagate through the whole refinery. In my opinion the best system will combine flows from several contactors into reasonable sized ARU's. The systems should have interconnections so that an ARU can be taken out of service and still keep the contactors all online. When figuring out what contactors to link through a common ARU, you want to consider things like capacity and common turnarounds, to simplify taking the common ARU out of service for maintenance and inspection. Common interconnected piping systems can be challenging to get out of service for inspection, so particular attention should be paid on how to lay out the piping to alllow this activity.
27/05/2020 A: Morgan Rodwell, Fluor Canada Limited, morgan.rodwell@fluor.com
This usually depends on history more than logic. If the refinery was built in stages—as many have been—then you may have multiple sources (hydroprocessing units) and multiple amine circuits. However, if the refinery is built in a single step, it is common to have a single amine regeneration unit with appropriate equipment sparing (pumps, exchangers) to allow for maintenance and cleaning without shutting down the unit. If the local jurisdiction allows for times between inspections at least as long as the turnaround interval, this can work. This allows lean amine to be distributed to the source unit absorbers and the rich amine returned to the regenerator. One note - while lean amine can be distributed using a single network (one pipe leaving the regen unit at a single pressure, often with booster pumps in the high pressure destinations units), the rich amine lines should not be merged until they reach a flash drum / feed surge drum near the regeneration column. Trying to merge these lines early without first flashing them can lead to flow problems, surprisingly high backpressures and vibration.

The SRU on the other hand is often less reliable than the amine regeneration unit. For this reason, many plants have been built with 2 or even 3 SRU trains to obtain the desired onstream factor. A RAM model should be used to identify the correct configuration.
27/05/2020 A: Nagarathinam S Murthy, Ashphil Consultancy, Chennai, nssvdvr@gmail.com
It will be a luxury to have independent amine absorption and regeneration units for each HT, and an energy and OPEX waste too. Ideally, link all HTs in one group with a single regenerator and multiple absorbers depending upon process conditions in the HP and LP sections of HTs/ HCU. The Coker and FCC can be placed on another group as these units bring all HSAS into Amine system. A larger unit will have an online amine reclamation section to take out HSAS from circulating amines.
27/05/2020 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Headers for the lean and rich amine. Standby amine regeneration and SRU.