PTQ Q3 2026 Issue

temperature of the salt bed reduces salt consumption, the dissolved water content in ULSD, and the risk of dissolved salt carryover in the product. Adjustments to the air cooler inlet temperature at the stripper bottom heat exchanger may be necessary, provided the feed heater is not at mini - mum firing. Facilities have reported that online cleaning of the air cooler and maximising fan blade angles have effec - tively reduced salt dryer inlet temperature. • Coalescer performance: Consistent and effective coa - lescer performance is essential for the efficient operation of the salt dryer. An increase in water content at the salt dryer inlet, along with a decrease in brine density, may indicate coalescer underperformance when operating temperature and unit feed remain unchanged. The coalescer cartridge should also be designed for the maximum temperature that may be experienced during abnormal conditions such as temporary loss of air cooler fans during a plant-wide power failure. • Lining up or bypassing the salt dryer : During start-up, the salt dryer should be placed in service only after water content at the coalescer outlet has stabilised, to avoid excessive salt consumption. During an emergency shut - down, when the unit is under internal circulation from the low-pressure section to the feed section, the salt dryer should be bypassed to prevent chloride stress of stain - less-steel piping in the feed section and potential catalyst poisoning. • Channelling in salt bed : Once channelling develops within the salt bed, drying efficiency deteriorates significantly. These preferential flow paths appear to be irreversible

under normal flow conditions. Reducing or stopping the ULSD flow does not eliminate the channels. In such cases, the salt bed must be completely removed and replaced to restore uniform flow distribution and ensure effective drying. One refiner reported that their salt dryer loaded with cal - cium chloride (CaCl₂) had become fully lumped. Disposal of the resulting brine through the ETP was constrained by chloride loading limits, making the process time-consum - ing. After ensuring all required safety precautions, person - nel entered the vessel, mechanically raked and broke the lumped salt, and removed it in sacks. The spent salt was subsequently disposed of through an approved third party. • Transitioning from CaCl₂ to rock salt : If a refiner opts to switch from CaCl₂ to rock salt, adjustments to the ceramic ball layers must be considered due to the smaller size of rock salt. Additionally, the salt loading diagram should be reviewed to ensure the total salt mass remains consistent with the original design. Prabhas K Mandal is an Operations Engineer Specialist at Aramco. He has more than 30 years of experience in petroleum refining and supports front-end design development for capital projects. He holds a B.Tech in chemical engineering and an M.Tech in petroleum engineer - ing. Email: prabhas.mandal@aramco.com Rajib Talukder is a Process Specialist in the Global Manufacturing Excellence department at Aramco, Saudi Arabia. He has more than 30 years of experience in process engineering and holds a B.Tech in chemical engineering from NIT Tiruchirappalli, India. Email: rajib.talukder@aramco.com

PTQ Q3 2026