We are facing an issue of LPG product off spec due to total sulfur being high. We have an amine treating unit followed by caustic treatment with CFC technology (EIL). Since the caustic regeneration system is not working frequently, caustic dumping and fresh caustic (25 Be) charging is being done. While the CFC unit is designed for RSH 4500 ppm and 100 ppm H2S, actual numbers are H2S NIL and RSH 1350 ppm in LPG.
The following activities have been done so far:
a) Line up checked for mixing feed and product to rule out short circuiting
b) Caustic strength reconfirmed and dumping / charging increased
c) Circulating caustic flow has been maximized and presently it is ~19.5 m3/hr.
d) Caustic levels in contactors have been increased to 70% to increase residence time.
e) Feed to CFC was reduced from 58 to 50 m3/hr.
1. Is there anything which we are missing?
2. Is there any impact of Erha crude which we are processing in the CDUs?
3. What is the experience of troubleshooting in other Refineries?