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Refinery Caustic Treating

Ensure Refinery Final Product Quality Through Leading Edge Spent Caustic Removal

Caustic Treating

Process Description

Caustic treating 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.

 

Refinery Needs

 

  • Achieve oil production quotas via reliable treatment of mercaptans and hydrogen sulfide
  • Meet product quality specifications for haze and sodium levels
  • Protect and extend run life of downstream catalytic process units

 

 

Production Challenge / Pall Solution

 

 

Challenge 

 

Meet product specifications

Solution

 

Improve refinery productivity and product specifications by removal of spent caustic carryover via effective liquids and solids removal downstream of the extractor.

 

  • KO pots, sand beds, water washes, and salt towers may not effectively remove the stable spent caustic emulsion.
  • High efficiency PhaseSep® liquid/liquid coalescers reliably meet ‘clear and bright’ product specification and sodium levels downstream.

 

 

Challenge

 

Protect downstream catalytic process units

Solution

 

Improve protection of downstream process units by removal of spent caustic carryover via effective liquids and solids removal downstream of the extractor.

 

  • KO pots, mesh pads, cyclonic devices and conventional filter-separators may not effectively remove the stable spent caustic emulsion.
  • High efficiency PhaseSep liquid/liquid coalescers reliably meet ‘clear and bright’ product specification and sodium levels downstream.
  • Solid particle contaminants in the spent caustic may not be adequately removed by filters that exhibit unloading, media migration, channeling or poor sealing.
  • A range of filter elements is available to reduce suspended solids to improve the efficiency and life of the liquid/liquid coalescer.

 

 

caustic treatment process diagram

 

Key Application/Filter Recommendations (other applications not shown)

 

Application

1.

Prefiltration prior to liquid/liquid coalescer

Pall Product

 

Nylon or polyphenylene sulfide (PPS) 

Profile® filter

Customer Benefits

 

Low operating costs by improving the life of the liquid/liquid coalescer

2.

Spent caustic removal

 

PhaseSep® liquid/liquid coalescer in horizontal configuration

 

Assured production and quality by meeting specifications for haze and sodium levels

 

Prevents downstream unit downtime from caustic contamination of catalytic processes

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