Fractionation method and apparatus

Abstract

A fractionation column is provided with a feed inlet and three product outlets, with the product outlets including an overhead vapor outlet, a bottoms liquid outlet and a side draw outlet. A plurality of vertically spaced apart vapor-liquid contact trays are mounted in the column. A generally vertical partition is positioned within the column in a central region between an upper and a lower vapor-liquid contact tray and divides the central region into first and second chambers defined by the upper and lower trays, column shell and partition. The feed inlet opens into the first chamber while the side draw outlet opens into the second chamber. First control means is provided for controlling the various inputs and outputs of the column. Second control means is also provided for measuring various constituent portions of fluid mixtures within the column. Third control means controls the relative vapor flow rates between the bottom portions of the first and second chambers and the region of the column below the partition. Fourth control means is also provided for measuring a constituent of a fluid mixture in the upper region of the first chamber and controlling liquid flow to the top of the first and second chambers from a region of the column above the partition.