Vaporization Inside Horizontal Tubes—II Benzene-Oil Mixtures

Abstract This paper reports an investigation carried out to determine heat-transfer coefficients and pressure drops for mixtures of benzene and lubricating oil flowing inside a heated horizontal tube, and also includes an analysis of the pressure drops for the runs previously reported (1) for the flow of benzene and of water. The present data cover the following ranges: Velocity, 0.4 to 1.0 fps at the inlet and 16 to 200 fps at the outlet; feed composition, 13 to 94 weight per cent benzene; gage steam pressures, 2 to 120 psi; product compositions, 4 to 76 weight per cent benzene; total pressure drops, 1 to 12 psi. Average over-all coefficients of heat transfer, in Btu per hr per sq ft per deg F, range from 40 to 140 in the preheating section, and 45 to 470 in the boiling section. For a given feed composition the average coefficients per pass in the boiling section increase as vaporization progresses, but pass through a maximum and decrease due to depletion of volatile solvent in the liquid phase. When the same data are grouped by composition of the liquid phase, rather than that of the feed, curves are obtained which are very similar to those obtained for pure liquids.