CPC C07C 7/04 (2013.01) [B01D 3/007 (2013.01); B01D 3/143 (2013.01); B01D 3/146 (2013.01); C07C 7/005 (2013.01); C07C 9/10 (2013.01); C07C 11/08 (2013.01)] | 7 Claims |
1. A method of refining raffinate-2 comprising:
feeding a raffinate-2 containing n-butane, isobutane, and 1-butene to a first distillation column;
obtaining heavy raffinate-3 containing n-butane from a lower part of the first distillation column;
recovering an upper part fraction containing 1-butene from an upper part of the first distillation column;
feeding the upper part fraction containing 1-butene to a second distillation column; and
recovering a first lower part fraction rich in 1-butene recovered from a lower part of the second distillation column and a light raffinate-3 containing isobutane from an upper part of the second distillation column,
wherein heat of the upper part fraction recovered from the upper part of the first distillation column is fed to a second lower part fraction recovered from the lower part of the second distillation column through a first heat exchanger,
wherein the upper part fraction of the first distillation column is fed to the first heat exchanger to supply heat from the upper part of the first distillation column to the second lower part fraction through the first heat exchanger, a portion of the upper part fraction of the first distillation column passed through the first heat exchanger is fed as a middle feed stream to the second distillation column, and a remaining portion of the upper part fraction of the first distillation column passed through the first heat exchanger is refluxed as an upper feed stream to the upper part of the first distillation column,
wherein a position of the middle feed stream is lower than a position of the upper feed stream,
wherein an upper part pressure of the second distillation column is 4.7 kgf/cm2 or more, and
wherein an upper part pressure of the first distillation column is higher than the upper part pressure of the second distillation column by 3.5 kgf/cm2 to 5.5 kgf/cm2.
|