| abstract |
Thermally coupled extractive distillation; a feed stock (for example, a C4 or C5 cut from an ethylene plant) is distilled by thermally coupled extractive distillation to remove paraffins and mono-olefins as a raffinate stream, as well as acetylenic hydrocarbons in a separate steam, thus segregating the C4 or C5 diolefin, the process using extraction solvents such as acetonitrile (ACN), dimethyl formamide (DMF), furfural, acetone, dimethylacetamide or N-methyl-2-pyrrolidone mixed with 0-12 weight percent of water, a bottoms stream of virtually acetylene free solvent further being produced; thermally coupled extractive distillation utilizing one to three coupled vessels to produce at least two and preferably three discrete, different volatility streams therefrom, as well as an extractive solvent recycle stream. |