Systems and methods for enhancing the extractive section operability and modifying solvent heat recovery cycle in the separation of C4 mixtures

A method of separating a mixture of C4 hydrocarbons and a solvent, the method comprising:

• separating the mixture of C4 hydrocarbons and the solvent in a rectifier column to produce a top stream comprising at least some C4 hydrocarbons and a bottom stream comprising (a) primarily the solvent and (b) some C4 hydrocarbons;
• separating the bottom stream in a degasser column to produce a lean solvent stream comprising primarily the solvent;
• wherein a reboiler for the rectifier column comprises four or more heat exchangers in series, wherein at least three of the heat exchangers are operated using the lean solvent stream as a heating medium, and wherein a last heat exchanger of the four or more heat exchangers in series is operated using low pressure steam as a heating medium;
• wherein the degasser column is operated at an overhead boiling temperature range of 85 to 100° C.;
• and
• wherein the method further comprises steps of:
• flowing the lean solvent stream to at least one of the four or more heat exchangers as a heating medium for the reboiler to heat a rectifier feed stream to produce a first cooled lean solvent stream and a heated rectifier feed stream;
• and
• flowing the low pressure steam to the last heat exchanger of the four or more heat exchangers as a heating medium to heat the reboiler to heat the heated rectifier feed stream and produce a further heated rectifier feed stream.