PTQ Q1 2026 Issue

into the TPA section, leading to heat transfer issues in the heat exchangers as well. At the time of programme initia - tion, the tower differential pressure was already at a high level, though the trend had plateaued. On the other hand, the TPA section fouling trend continued to deteriorate (see Figure 4 ). Therefore, to avoid further fouling build-up and potential under-deposit corrosion in the TPA section, the programme was applied to the TPA section inlet side. The dosage and application were adjusted based on diagnostic feedback and performance indicators. Within one week, changes began to appear, and after one month, a clear recovery trend in the TPA heat transfer and tower differential pressure was observed. After two months, the fouling condition of the tower and TPA section had recov - ered to start-up levels. The unit maintained stable operation until the scheduled turnaround, and no off-spec products or abnormalities were observed during the treatment period. Post-turnaround inspection confirmed that there were no deposits or corrosion on the trays or heat exchangers. Conclusion This article has examined the causes of salt-related issues in FCC units, their critical impact on refinery profitability under current market trends, and the available counter - measure technologies, including an actual case study. Various approaches exist for salt mitigation; in some cases, a combination may be required. Since equipment structure, operating conditions, and contaminant profiles vary significantly across refineries and feedstocks, no single solution can universally address all the salt-related issues. However, by incorporating addi - tive-based countermeasures as part of the overall strategy, refineries can enhance their asset protection and opera - tional safety while maintaining profitability. To respond to increasingly unpredictable market and feedstock trends, expanding the range of available options is essential. The authors would like to express their sincere gratitude to Mr. Cuong Kevin Le, Senior FCC Technologist of Shell Global Solutions Inc, and Mr. Gage Fos, RCCU Operations Support Engineer of Shell Energy and Chemicals Park, Norco, for their invaluable support and insights during the implementation of this study. References 1 Kumar, S., Otzisk, B., Urschey, M., Managing ammonium salts corro - sion and fouling, PT Q Q3 2021 . 2 Koizumi, M., Karaki, K., Salty Business, Hydrocarbon Engineering , Nov, 2017. 3 Niccum, P., Mcdaniel, W., Pollicoff, H., FCC product fractionation for maximum LCO, PTQ O3 2017 . 4 Dean, C.F., Golden, S.W., Main fractionator water wash systems, PTQ O3 2006. 5 Otzisk, B., Urschey, M., Raising diesel yields by chemical treatment, PTQ O4 2020. Keisuke Karaki is a Chief Engineer for refinery and petrochemical pro - cess applications with Kurita Water industries Ltd. located in Japan. Email: k.karaki92@kurita-water.com Arthur Lamm is an Industry Consultant for refinery and petrochemical field solutions with Kurita America, Inc. located in the US. Email: a.lamm@kurita-water.com

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TPA H/E T (degF) RFCC unit feed

Main fractionator Top~TPA P (mmHg) Program me applied period

Figure 4 TPA section heat transfer and tower fouling trend

has been implemented in various refinery and process units without affecting product quality. Case study In a US refinery, a residue FCC unit (RFCC unit) with a capacity of 100,000 BPD had been processing atmos - pheric residue (AR) and vacuum residue (VR) and up to 50% of purchased gas oil as feedstock. Stable operation as well as corrosion and fouling in the main fractionator and surrounding equipment were controlled through rigorous monitoring, frequent analysis, and correct control of dew point and salt deposition temperatures. However, in the attempt to further increase refinery mar - gins, a new type of opportunity crude was introduced to the refinery feedstock. The new crude and purchased gas oil was later found to contain high levels of chlorides and bromides, which significantly increased the salt deposition risk within the RFCC unit. Simultaneously, due to declining gasoline demand, the refiner decided to change the RFCC unit operation to diesel maximisation mode by lowering the tower top temperature and naphtha end point. The combination of reduced temperature and increased acid partial pressure led to substantial salt deposition in the tower (see Figure 3 ), resulting in elevated differential pres - sure across the tower top to LGO section and reduced heat transfer in the top pumparound (TPA) section. These issues not only restricted the planned diesel production and opportunity crude processing but also threatened the unit’s ability to operate until the scheduled turnaround. Initially, the refinery applied a salt dispersant, which improved the differential pressure of the tower; however, it subsequently caused significant fouling in the downstream processing units. To address the situation, the proprietary Ammonium Chloride Free technology was applied as a new approach. Based on a comprehensive diagnosis, including fouling trends, process conditions, and analytical data, the salt dep - osition load and locations were estimated. The fouling was attributed to salt deposition in the main fractionator top trays, which subsequently carried down

PTQ Q1 2026