Technology Type

Caustic treatment is used to upgrade a wide range of Liquid Fractions from LPG to Diesel Fuels and Heating Oils. As the Caustic Solution (and often a Catalyst) mixes with the Hydrocarbon Feed it either extracts or sweetens Mercaptans, depending on the Process used.

However, the combination of the Hydrocarbon and Mercaptan Rich Caustic also forms a very stable Emulsion that is difficult to Separate, causing significant quantities of Caustic Carryover in the Product. This results in off-specification Products due to haze or elevated sodium concentration and loss of Caustic. In many cases the entrained Caustic is fed to Processes where Sodium is a Poison to the Catalyst.

Because the Emulsion is so stable, Knock-Out Drums, Sand Filters and Packed Vessels are not able to efficiently separate the Caustic Emulsion from the Hydrocarbon Streams. High efficiency Phase Separators such as Liquid/Liquid Coalescers reliably meet ‘clear and bright’ Product specification and Sodium levels downstream. Filter Elements are employed to reduce suspended Solids to improve the efficiency and life of the Liquid/Liquid Coalescer.

Example of Fuels Caustic Processes are:

• UOP Merox™ Process
• Merichem Napfining™ Process
• Merichem Mericat Processes