PTQ Q4 2024 Issue

efficacy was not consistent. Even though 80% removal efficacy was observed when solids were >300 PTB, with changes in solids in the feed, a 50-60% solids removal tar- get is consistently achievable. At the same time, no desalter performance issues or downstream heat exchanger fouling was observed. Based on these learnings, targeting oil-in- soluble solids seems to be the best breakeven point for a good solids removal target of 50-60% removal. Solids removal efficacy was compromised with infre- quent mud wash frequency. When desludging operations were performed every four days (because the refinery has four desalters, with Train A having two desalters and Train B having two desalters, each day one desalter was mud washed in a cycle), the four-day frequency resulted in sol- ids accumulation in the desalter bottom, affecting residence time and limiting solids removal. Consequently, the mud wash frequency was optimised to every two days for each desalter, achieving 50-60% solids removal efficacy in the desalted crude, without heat exchanger performance drop or solids build-up in the emulsion layer. Additionally, it was recommended to use the solids wet- ting agent in the mud wash water period. Solids wetting helps move sticky solids from the desalter bottom and reduces desludging or mud wash durations. For example, in the Southeast Asian refinery where desalter optimisation was managed, normal desludging operations were per- formed for 45-70 minutes. However, with wetting agents in the mud wash water, the cleaning time was reduced to less than 30 minutes (see Figure 7 ). Overall, mud wash is an essential aspect of reducing the emulsion layer band thickness, promoting a sharp interface level, and sustaining the design residence time. Note: It is highly recommended to establish a daily mud wash opera- tion if the incoming crude contains more than 60 PTB (180 ppm) of solids. Conclusion The cost of poor desalting is significantly high. From the desalter survey, it is evident that crude blend quality varia- tions drive the day-to-day desalter key parameter optimisa- tion using basic data analysis tools. The brief overview and key performance factor optimisation strategies followed in this real-time refinery case study exemplify the critical role of strategic parameter management in refining operations. Adopting a holistic approach to operational parameter opti- misation, integrated with the best chemical treatment pro- gramme, enabled the refinery to consistently meet desalter performance indicators. This ensured sustained operational excellence and profitability in a dynamic refinery market envi- ronment. The key takeaways from this case study include: • Understand the interdependencies among factors like crude quality, operating conditions, equipment design, and chemical treatment in desalter optimisation. • Establish safe operating boundaries for critical parameters through data analysis, troubleshooting discrepancies, and periodic calibrations. • Optimise key parameters synergistically, considering their interdependencies (for example, temperature for viscos- ity and water solubility, mix valve DP for droplet size and

9 8 10

0 3 2 1 4 5 6 7

Start mud wash

Recommended mud wash duration

10 12 14 16 18

2 4 6 8

20 22 24 26

30 32

Time (minutes)

Figure 7 Mud wash optimisation – reduce desalter upsets

distribution, wash water for conductivity and coalescing force, interface level for residence time and emulsion control). • Implement a comprehensive chemical treatment pro- gramme, including demulsifier selection, wetting agents, and pH modifiers, based on emulsion studies and brine chemistry. • Continuously monitor performance, validate results during crude changes, and make proactive adjustments to opera- tional and chemical factors. • Leverage basic statistical tools and benchmarking for iden- tifying and addressing influencing parameters periodically. • By following a systematic optimisation approach and integrating best practices, refineries can overcome the challenges of crude oil desalting, minimise the associated costs, and achieve sustained operational excellence, even in dynamic market conditions. Acknowledgement The author would like to express his gratitude to the Veolia team, includ- ing Mike Dion, Sumalya Nag, Nimesh Kumar Patel, Martin Willis, Ching Yaw Lee, and Piravin Mageswaran, for their valuable contributions. Special thanks go to the Southeast Asian refinery CDU Process Manager and Specialist Distillation team, Saiful Dzulfitri, Azamuddin Jameran, Nor Atifah Binti, and Chua Wee Kheng, for their intense support and motiva- tion during the on-field troubleshooting and optimisation activities. References 1 Potential Effects of Upstream Additives on Refinery Corrosion and Fouling, NACE Technical Committee Publication 21415-SG. 2 Kapusta S, van den Berg F, Daane R, Place M C, Impact of oilfield chemicals on refinery corrosion problems , Paper no. 03649, Corrosion 2003. 3 Dion M, Desalting opportunity crude , NPRA Spring National Meeting, March 1995. 4 Desalter Training Manual, Veolia Water & Process Technologies. 5 Gutzeit J, Controlling unit overhead corrosion: rules of thumb for better crude desalting , Paper no. 07567, Corrosion 2007. 6 Shooshtari M, Karimi M, Panahi M, Modelling of an industrial mix- ing valve and electrostatic coalescer for crude oil dehydration and desalination, Separation Science & Technology 2023 , Vol 58, No.7, pp.1,306-1,318. Venkatesan Mani is Senior Product Manager and Application Expert for Veolia Water Technologies and Solutions for Southeast Asia & Oceania region, responsible for speciality chemical solution design and applica- tion expertise in refinery and petrochemical process technologies. He holds a BTech in chemical engineering from Anna University, Chennai, India.

PTQ Q4 2024