No More Inefficient Crude Desalting - Breaking Bottleneck with Dual Frequency Technology Lowering Total Cost of Ownership

Historically, the engineering and operations teams in refineries have been constantly challenged to deploy efficient solutions for their crude desalting processes as part of the crude distillation unit (CDU). Inefficient crude oil desalting employing AC technology leads to higher utility consumption and corrosion-related issues with downstream equipment that create multiple bottlenecks while processing opportunity crudes. In addition, these challenges lead to a significant increase in operating expenses due to processing upsets and subsequent downtime. A major independent crude oil refinery in Asia is processing crude oil in two CDUs utilizing an AC technology desalting system. The total design capacity for the CDU is 206,000 BPD. The first CDU desalting equipment is designed for 150,000 BPD, and the second CDU is designed for 56,000 BPD. Both CDUs were operated in a range of 10 to 30 PTB inlet salinity. However, due to inefficient desalting, less than 60% desalting efficiency was achieved for each train with subsequent low dehydration efficiency. This led to a considerable bottleneck with the processing capacity and much higher chemical consumption, accompanied by frequent upsets and operational issues on downstream equipment. After a review of the entire desalting operations, the CDU 1 desalter vessel was upgraded to dual frequency technology, and a new dual frequency desalter was installed at the second stage of CDU 2. This change provided a paradigm shift in handling opportunity crude blends in the range of crude density 21 to 28° API with the flexibility of 20 to 100 PTB inlet salinity. After the upgrade, the CDUs achieved a desalting efficiency of more than 90% on each stage and more than 99% on two stages. This paper examines the project from early engagement through conceptual technology selection phase, engineering design, and project execution leading to a successful startup backed by operational history. Furthermore, the adoption of dual frequency technology over legacy AC technology demonstrates the twin goals of positive economic and environmental stewardship, thereby lowering the total cost of ownership to the customer. The CDU 1 dual frequency technology retrofit has been in continuous operation since 2019 and performing well within the PTB outlet specifications. The system is running with 40 to 50 % lower utility consumption, both chemical and power savings with reduced downstream corrosion and an increase in uptime reliability.