An alkylation unit converts the feedstock, typically isobutane or alkenes, into alkylate. Alkylate is a high-octane blending agent for gasoline. The conversion is completed by use of a strong acid, which is typically sulfuric acid (H2SO4) or hydrofluoric (HF) acid. A common alkylation unit will have feed preparation, reaction, treating, refrigeration, and fractionation sections.
Hydrocarbon Feed Section
Koch-Glitsch has successfully installed liquid-liquid coalescers in the hydrocarbon feed prior to the alkylation reactor. The designs use a variety of products depending on the specific application to reduce the water content to 15 vppm.
Koch-Glitsch has successfully installed liquid-liquid coalescers in the reactors and settlers to produce tremendous savings for the refinery, including acid recovery, improved alkylate, increased settler capacity, and decreased downstream corrosion for flares, knockout drums, and piping.
Koch-Glitsch has excellent experience with the effluent neutralization section related to the acid wash, water wash, alkaline water wash, depropanizer feed, and deisobutanizer (DIB) feed drums. Liquid-liquid coalescers and associated internals are utilized in these vessels.
To prevent damage to the reciprocating compressors in the auto-refrigeration circuit, mist elimination equipment is utilized to remove the entrained liquid droplets. DEMISTER® mist eliminator, DEMISTER-PLUS mist eliminator, and YORK-EVENFLOW vane inlet devices are common in this application.
There are alternate designs for the fractionation section; however, a majority of the units will have a depropanizer and DIB column. The columns will typically utilize trays with either MINIVALVE® trays or FLEXIPRO® valve trays being used as the initial design basis. This allows for future expansion capabilities by utilizing either SUPERFRAC® trays or ULTRA-FRAC® trays.