Patent TW-323962-B (TW)
Title: Separation process of a multi-component stream using a distillation system with multiple towers
Inventor: RAKESH AGRAWAL
IPC: F25J3/04
Filed: 1993-03-02
Granted: 1998-01-01
Abstract: A process of separating a multi-component stream, in which the multi-component stream comprises at least a volatile component A and a less volatile component C and a component B with a volatility between that of components A and C, in which the multi-component is introduced into a distillation system with multiple towers, the system combines a side tower which effectively separates the multi-component stream and obtains at least one component; in a distillation system with multiple towers comprising a main distillation tower and a side tower to obtain an increased production of the component B from a stream containing at least components A, B and C, the improvements comprise the following steps: (a) withdrawing a liquid part from the main distillation tower, in which the liquid part is enriched in the component B but is contaminated with the component A and contains the component C at a low concentration, in which the component A is more volatile than the component B and the component B is more volatile than the component C; and feeding the fluid part into a stripping area in the side tower; (b) withdrawing a vapor part from the main distillation tower, in which the vapor part is enriched in the component B but is contaminated with the component C and contains the component A at a low concentration; and feeding the vapor part into a rectification area in the side tower; (c) withdrawing the component B with a pre-specified concentration from a location on the side tower, in which the location is between the introduction location of the fluid part enriched with the component B (however, containing an obviously low concentration of the component C) and the introduction location of the vapor part enriched with the component B (however, containing an obviously low concentration of the component A); (d) withdrawing a vapor part enriched in the component A from a stripping area of the side tower and recycling it to the main distillation tower; (e) withdrawing a liquid part enriched in the component C from a rectification area of the side tower and recycling it to the main distillation tower; and (f) thermally combining the side tower and the main distillation tower, which comprises at least the following (i) and (ii) steps: (i) vaporizing at least a part of a fluid part obtained from the side tower by a distilled part obtained from the main distillation tower such that at least a part of the vapor part obtained from the main distillation tower is partially condensed and at least a part of the liquid part obtained from the side tower is partially vaporized; recycling at least a part of the condensed vapor part from the main distillation tower to the distillation system with multiple towers; and recycling at least a part of the vaporized liquid part from the side tower to the distillation system with multiple towers; and (ii) condensing at least a part of a vapor part obtained from the side tower by a fluid part obtained from the main distillation tower such that at least a part of the liquid part obtained from the main distillation tower is vaporized and at least a part of the vapor part obtained from the side tower is condensed; recycling at least part of the vaporized liquid part from the main distillation tower to the distillation system with multiple towers; and recycling at least part of the condensed vapor part from the side tower to the distillation system with multiple towers; in which the main distillation tower is a double-tower system which comprises a high pressure tower and a low pressure tower, and the multi-component stream is air.