Upon becoming the refinery’s chemical solutions provider, Veolia focused on reducing the oil content in the desalter effluent water (brine). This cost the refinery lost feedstock and additional oil loading to the wastewater treatment plant that wasn’t recoverable.
A multi-step improvement program was developed with the refinery to fine-tune all operational aspects of the desalter operation to their crude oil operating envelope. These improvements were implemented over several months:
- A mix-valve study measured desalted crude chlorides and BS&W with changing pressure differential. This determined the optimal mix-valve setting for the first and second stage desalters.
- Level control was optimized over time with routine inspection of the tri-line samples.
- The emulsion breaker best suited for the refinery’s crude and desalting operation was selected using Veolia’s unique desalter simulator.
- Adjunct chemistry was added to assist with emulsion resolution control.
- Mud washing practice was optimized from continuous to intermittent, which reduced nozzle velocity to their design, resulting in a more stable emulsion layer and control of solids. Quarterly temperature surveys confirm no mud build-up in the desalter vessels.
- Training and engagement with unit operations to maintain performance as improvements were made.
Result
As the desalter’s operation improved over time, average oil in brine reduced from 13,000 PPM to <500 PPM. This reduced the fouling potential in the brine heat exchangers and reduced slop to be handled in a wastewater plant.
The oil recuperated from the brine through these improvements is estimated at ~26,000 barrels per year, a value of over $900,000 for the refinery.