Refinery HF Alkylation

Olefins (C3-C4) from the FCC unit are combined with isobutane (i-C4) and are first treated with a mol sieve bed to remove water. Concentrated Hydrofluoric Acid (HF) is then mixed in and fed to the reactor. The alkylation reaction takes place combining the olefins with the isobutane to form the alkylate product which consists of high octane value products that are later blended into the gasoline pool. The hydrocarbons leaving the reactor mostly consist of alkylate, unreacted isobutane, n-butane, and propane.

The HF and alkylate product are separated by a settler and the HF is recovered for re-use in the reactor. The reactor hydrocarbons are separated by the main fractionator where the isobutane is recycled to the reactor, alkylate is drawn off the bottom and an n-butane product stream is separated and treated with caustic (KOH).

The overheads consist mostly of HF acid fumes and propane gas. The overheads are then cooled and the HF separated. Propane is further treated through the propane splitter to remove any dissolved HF and finally treated with alumina to remove fluorinated organics, and then caustic (KOH) to neutralize any remaining acid. Effective separation is a critical component of an efficient, reliable and safe H2SO4 alkylation process.

Refinery Needs

• Equipment reliability/minimized corrosion to meet 4-6 year refinery turn around schedule
• Meet product specs for high octane value alkylate and caustic free propane and n-butane
• Low acid makeup costs by minimizing acid dilution from wet feedstocks
• Maintain high levels of safety by avoiding any equipment failures that could lead to fugitive emissions of HF

Production Challenge/Pall Solution

Key Application/Filter Recommendations (other applications not shown)

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