Process for N-butanizing field butane feedstock to thermal crackers

A method of increasing n-butane concentration in field butane, the method comprising:

• subjecting a feed stream, comprising primarily n-butane and isobutane collectively, to a concentrating process, the concentrating process comprising distilling the feed stream in one or more distillation columns to produce a first product stream comprising primarily n-butane and a second product stream comprising methane, ethane, and propane;
• and
• cracking, in a thermal cracker, the first product stream to produce a third product stream comprising primarily ethylene and a fourth product stream comprising primarily n-butane;
• and
• recycling, from the thermal cracker, at least some of the fourth product stream to the one or more distillation columns;
• wherein the concentrating process comprises:
• distilling, in a first distillation column, a combined stream that comprises a mixture of the feed stream and a recycle stream comprising primarily isobutane to produce a bottoms stream comprising primarily n-pentane, an intermediate stream comprising primarily n-butane, and an overhead stream comprising primarily isobutane;
• combining the intermediate stream and the bottoms stream to produce the first product stream;
• isomerizing the overhead stream in a reactor to convert at least some of the isobutane in the overhead stream to n-butane;
• and
• distilling effluent from the reactor, in a second distillation column, to form the recycle stream and the second product stream.