Distillation apparatus

A distillation apparatus comprising in combination:

• a first distillation column,
• a second distillation column,
• a compressor,
• a first heat exchange means connected to said first distillation column at the bottom of said first distillation column,
• a second heat exchange means connected to said second distillation column at the bottom of said second distillation column, and means for removing overhead streams and for removing bottoms streams from each of said first and said second distillation columns, wherein
• said first distillation column is equipped with from about 70 to about 100 plates,
• said second distillation column is equipped with from about 5 to about 20 plates,
• means is provided for supplying an organic hydrocarbon feed to about a mid-point of said first distillation column,
• means is provided for supplying a first portion of the bottoms stream from said first distillation column to an upper point of said second distillation column,
• means is provided for circulating a second portion of the bottoms stream from said first distillation column to said first heat exchange means wherein it is subjected to indirect heat exchange with a stream from said compressor,
• means is provided for circulating a bottoms stream from said second distillation column to said second heat ecxhange means wherein it is subjected to indirect heat exchange with a supply of hot water or steam,
• means is provided for supplying an overhead stream from said second distillation column to a lower point of said first distillation column,
• means is provided for removing a high boiling component stream from the bottom of said second distillation column,
• means is provided for removing as purified product a portion of the overhead stream from said first distillation column,
• means is provided for supplying a second portion of the overhead stream from said first distillation column to said compressor wherein said vapor is compressed and heated,
• means is provided for circulating the heated compressed vapor stream from said compressor to said first heat exchange means wherein it is liquefied and cooled by indirect contact with said second portion of the bottoms stream and then to a point in the overhead stream from said first distillation column.