Abstract:
Mixtures of hydrocarbons predominantly having 4 carbon atoms per molecule known as C4 cuts are used in obtaining crude 1,3-butadiene by a thermal cracking process. Vaporous purified crude C4 cuts are produced from liquid crude C4 cuts, containing butanes, butenes, 1,3-butadiene, C3 hydrocarbons, C4 oligomers and polymers, and C5+ hydrocarbons via an extractive distillation by fist removing the C4 oligomers and polymers and the C5+ hydrocarbons and then vaporizing the liquid crude C4 cut in a vaporizer vessel. The vaporizer vessel is directly or indirectly in contact with a stripping column where liquid C4 cuts are supplied to the upper region, direct gas and liquid exchange with the vaporizer vessel occurs in the lower region, and vaporous purified crude C4 cuts are removed from the top region.
Abstract:
Process for isolating pure 1,3-butadiene from a crude C4 fraction by extractive distillation using a selective solvent, wherein (a) the crude C4 fraction is introduced into a predistillation column, a first low boiler fraction comprising C3-hydrocarbons is taken off as overhead stream, a gaseous C4 fraction is taken off as side stream and a first high boiler fraction is taken off as bottom stream, (b) the gaseous C4 fraction is brought into contact with a selective solvent in at least one extraction column, giving an overhead fraction comprising butanes and butenes and a bottom fraction comprising 1,3-butadiene and selective solvent, (c) crude 1,3-butadiene is desorbed from the bottom fraction in at least one stripping column, with a stripped selective solvent being obtained and the stripped selective solvent being recirculated to the extraction column, and (d) at least part of the crude 1-3-butadiene is fed to a pure distillation column and a second high boiler fraction is separated off and a gaseous purge stream is taken off. Gaseous purge streams from the columns which are necessary in order to keep the concentration of molecular oxygen below a predetermined concentration limit are consolidated with output streams which are in any case provided for discharging other components in the process. The recirculation of the second high boiler fraction to a lower section of the predistillation column creates a further degree of freedom in operation of the pure distillation column.
Abstract:
A process for isolating pure 1,3-butadiene from a crude C4 fraction, which produces pure 1,3-butadiene having a prescribed maximum content of at least one low boiler and a prescribed maximum content of 1,2-butadiene, in each case based on 1,3-butadiene, wherein (a) a low boiler fraction and a high boiler fraction are separated off by distillation from the crude C4 fraction, giving a purified C4 fraction whose content of the at least one low boiler, based on 1,3-butadiene, is equal to or lower than the prescribed maximum content of the at least one low boiler and whose content of 1,2-butadiene, based on 1,3-butadiene, is equal to or lower than the prescribed maximum content of 1,2-butadiene; (b) the purified C4 fraction is subjected to at least one extractive distillation using a selective solvent, giving at least a fraction comprising butanes and butenes and a pure 1,3-butadiene fraction, is described. The process makes a pure distillation column dispensable.
Abstract:
A distillation device comprising a column for separating a feed stream into a head product stream, a bottom product stream and optionally one or more side extraction streams, having three or more cells in 5 series through which fluid flows, wherein at least the first cell is integrated into the bottom of the column, for multi-stage heating and partial evaporation of the liquid flowing through the cells with the exception of the liquid from the last cell in an evaporation stage.
Abstract:
What is proposed is a column (K) comprising separatory internals (E) for separating a mixture of hydrocarbons and/or hydrocarbon derivatives (1) by extractive distillation with a selective solvent (2),with supply of the selective solvent (2) in the upper region of the column and supply of the mixture of hydrocarbons and/or hydrocarbon derivatives to be separated (1) below the supply of the selective solvent (2), the selective solvent (2) becoming laden in the column (K) with the components from the mixture to be separated (1) for which it has greater affinity and being withdrawn from the lower region of the column as laden selective solvent (3), while, by contrast, the components from the mixture to be separated for which the selective solvent (2) has a lower affinity remain in the vapor phase and are withdrawn as top stream (4), which is completely or partially condensed to obtain a condensate (5), some of which is withdrawn as product stream (6), the remainder being reintroduced to the column (K) as reflux (7), wherein said column comprises in the region of the column above the separatory internals (E) a first, substantially horizontal feed pipe (R1) for supplying the selective solvent, wherein the first, substantially horizontal feed pipe (R1) exhibits a cross-sectional narrowing to a narrowest point (V), said pipe widening again downstream of the cross-sectional narrowing, and wherein said column comprises a second feed pipe (R2) for supplying the reflux (7), said pipe joining the first, substantially horizontal feed pipe (R1) in the region of the narrowest point (V) of the cross-sectional narrowing.