Butane Isomerization - continued.

The reactor product (which contains butane and newly-formed isobutane) is cooled and routed to an accumulator (high pressure separator). Hydrogen rises to the top of the accumulator and is routed to the suction of the compressor A. The stream B indicates the makeup stream for hydrogen.

Liquids from the accumulator are routed to a stabilizer. In the stabilizer, light-ends are separated as fuel gas and the rest is routed to the incoming feed. The newly formed isobutane is isolated in the de-isobutanizer as the final product.

In a typical low-temperature process, the feed to the isomerization plant is n-butane or mixed butanes mixed with hydrogen and passed to the reactor at 230-340 deg F (110-170 deg C) and 200-300 psi. Hydrogen is flashed off in a high-pressure separator and the hydrogen chloride removed in a stripper column. The resultant butane mixture is sent to a fractionator (deisobutanizer) to separate n-butane from the isobutane product.