Extractive distillation column system and the use thereof in the separation of butenes from C4-hydrocarbon streams

An extractive distillation column system for separation of butenes from a C4-hydrocarbon stream which contains at least butenes and butanes using a solvent, wherein the extractive distillation column system comprises:

• a combination column, and
• a side rectification column,
• wherein the combination column from top to bottom comprises at least the following different sections:
• a top section in which a stream enriched in butanes compared to the C4-hydrocarbon stream is obtained;
• a random packing section which comprises at least two random packing beds;
• a collection section which comprises at least two liquid collectors;
• a regeneration section which comprises at least one further random packing bed;
• and
• a bottom section in which the solvent is obtained;
• wherein arranged on the combination column are at least two side evaporator systems, wherein in each evaporator system a liquid phase from one of the at least two liquid collectors of the collection section is at least partially evaporated and subsequently recycled via a respective first inlet or second inlet to the collection section, wherein the first inlet is arranged spatially at least one liquid collector above the second inlet;
• and
• wherein the side rectification column comprises at least two separating trays or at least one random packing or structured packing bed and is supplied with a gaseous phase which is obtained from the collection section of the combination column at a location below the first inlet but above or at a same height as the second inlet.