METHOD FOR INCREASING CAPACITY OF AN EXTRACTION PLANT FOR THE EXTRACTION OF BUTADIENE- (1,3) FROM C (DOWN ARROW) 4 (DOWN ARROW) -HOLID HYDROGEN MIXTURES WITH SIMULTANEOUS RECOVERY OF BUTES (2)

摘要

1. A process for increasing the capacity of an extraction plant for the recovery of 1,3-butadiene from C4 -hydrocarbon mixtures and for the recovery of 2-butene by extraction of a butadiene-containing C4 -cut in a first extraction stage A and a second extraction stage B with an intervening distillation column C and a subsequent distillation column D, characterised in that a part of the 2-butene is withdrawn with the crude butadiene from the second extraction stage B and is separated from 1,3-butadiene and higher boiling hydrocarbons by means of a plurality of subsequent distillation stages, the amount withdrawn at the head of the second extraction stage B being increased to such an extent that it contains up to 3% by weight of cis-2-butene in the crude butadiene which has a purity level of less than 99%, simultaneously the amount withdrawn from the sump of the subsequent second distillation column D being increased to such an extent that a pure butadiene with a purity of more than 99.5% and a cis-2-butene content of less than 0.5% is obtained at the head of this distillation column, the bottoms from this column being fed to a third distillation stage E in which the remainder of the pure butadiene is obtained as overhead product, and the bottoms product of the third distillation stage E being passed to a fourth distillation stage F in which high-purity 2-butene is recovered as overhead product.