Q & A > Question Details
We are facing frequent issue of moisture carryover in the light naphtha stream to our hydrotreater. Does anybody have experience of putting a salt drier in the hydrotreater upstream to remove the moisture. What sort of damage it can cause to the catalyst?
 
Answers
07/08/2015 A: Yogesh Bhintade, Raffinerie Heide, bhintadeyogesh@gmail.com
A long term water/moisture carry over would create problem of fouling in unifiner unit and also to the downstream units (CCR (formation of cake) (Isomerization units/ Penex units catalyst will strongly deactivate).
30/06/2015 A: keith bowers, B and B Consulting, kebowers47@gmail.com
Water in naphtha is not a usual problem. Where is it comming from. Focus on fixing the source o the problem. Salt bed driers are not intended for bulk water removal, up to say 1000 PPM as a haze.
BE SURE and check total chlorides in the feed to protect any 300 series SS in the hydrotreater system. With a salt drier, risk increases. There are excellent cartridge filter style water coalescers available.
29/06/2015 A: Ganesh Maturu, Self, maturu.ganesh@gmail.com
Typical Naphtha hydrotreaters, a horizontal feed surge drum with a water boot can be used to separate free water from Naphtha feed. A separate salt drier may not be required in the feed to remove dissolved water. Since the entire feed is in vapor phase at the reactor inlet, dissolved water present in feed should not affect the catalyst performance. Presence of water in feed reduces the H2 partial pressure at the reactor inlet by very minimal amount and hence no catalyst adverse effect.
24/06/2015 A: Sarath Konda, DuPont India, sharathsatya@gmail.com
Fresh catalyst has a higher activity and has a good hydrogenation function, which results in higher H2 consumption and has higher density reduction with better product quality. Typically during EOR, catalyst has activity declines (due to coke deposition on catalyst), which results in less hydrogenation reactions taking place with lower H2 consumption. Depending upon the type of catalyst impact on the product quality like sulfur varies. If HDS catalyst is a CoMo type, impact on product sulfur level tends to be minimal as it attacks sulfur removal directly compared to NiMo which prefers hydrogenation route. Bed temperature has to be increased at EOR to meet the product quality; increase in temperature only bridges the activity loss due to coke deposition on the catalyst.
24/06/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Not a good idea if the hydrotreater metallurgy is 300 series stainless. Chlorides would cause stress corrosion cracking.