METHOD FOR PROVIDING A PURIFIED CRUDE GASEOUS C4 FRACTION AS AN INPUT STREAM FOR AN EXTRACTIVE DISTILLATION USING A SELECTIVE SOLVENT

摘要

The invention relates to a method for providing a purified crude gaseous C4 fraction (2) as an input stream for an extractive distillation using a selective solvent in order to obtain crude 1,3-butadiene on the basis of a liquid crude C4-fraction (1) as a feed stream, containing C3 hydrocarbons, C4 oligomers, C4 polymers, and C5+ hydrocarbons together with butanes, butenes, and 1,3-butadiene. The method has the steps of 1) separating the C4 oligomers, C4 polymers, and C5+ hydrocarbons up to the respective residual content previously specified for the purified crude gaseous C4 fraction and 2) evaporating the liquid crude C4 fraction in an evaporator tank (VK). The invention is characterized in that the evaporator tank (VK) is associated with a stripping column (K) with one or more separating stages, the liquid C4 fraction (1) being fed to the stripping column in the upper region of the stripping column. The stripping column directly exchanges gas and liquid with the evaporator tank (VK) in the lower region of the stripping column, and the purified crude gaseous C4 fraction (2) is drawn off from the stripping column in the upper region. The stripping column (K) is operated without a condenser at the column head.