Pall's AquaSep® Liquid/Liquid Coalescer System Reduces Salt Consumption and Provides On-Spec Diesel Fuel

Paul Cuerou
Market Sales Manager - Hydrocarbons

Success Story
March, 1999

Case History

A major southeastern refinery processes 240,000 BPD of crude oil. Diesel fuel is produced at a rate of approximately 50,000 BPD. The diesel fuel passes through an air cooler and water-cooled heat exchanger prior to being sent through an electrostatic precipitator (ESP) and salt bed. These units remove free and dissolved water necessary to meet the required haze specification.


Problem Area

The design capacity of the existing ESP is approximately 42,000 BPD. Once the flow rate exceeds 42,000 BPD the ESP becomes less efficient due to reduced residence time. Diesel fuel laden with excessive amounts of free water (i.e., greater than 250 ppmv) is sent to the CaCl2 salt beds causing channeling and a high rate of salt consumption. At a total process flow rate of 50,000 BPD, salt is being replaced monthly which is twice the expected rate. The cost to replace the salt bed is $30,000.



The operator installed Pall's AquaSep Liquid/Liquid Coalescing System to function in parallel with their existing ESP unit. The filter and coalescer assemblies are designed to handle 8,000 BPD of diesel fuel at normal operating conditions. The system configuration consists of a 9 element pre-filter assembly followed by a 19-around vertical AquaSep Liquid/Liquid Coalescer Unit. Pall's AquaSep System produces effluent with less than 15 ppmv free water. The 8,000 BPD diesel stream processed by the Pall System is combined with the ESP treated diesel stream for processing through the salt beds.



Pall's AquaSep system allowed the operator to increase diesel fuel throughput, reduce salt consumption and consistently meet haze specifications. The salt savings are approximately $180,000 annually. The system was placed in operation in September of 1996. The prefilter elements are replaced every four months. The original set of AquaSep Liquid/Liquid Coalescer elements are still in service.