Backward-Feed Distillation Column

Abstract

Although the flow conditions here do not conform to those behind the basi'c equation, it is possible to carry out formally a calculation of the absolute viscosity of the soap by means of Equations 1 and 2, using F -/b instead of F. Assuming the density to be 0.8 and taking values of F and U from the linear portions of the curves of Figure 8, the apparent viscosity of converter soap C is 4.95 X 104 poises with a wire of 0.0150-cm. radius. With a 0.0206-cm. wire also calculates to be 4.95 X 104 poises. Despite this agreement the significance of the figures is questionable, since the complex nature of the flow has not been taken fully into account in any of the equations. Interestingly, McBain.and Watts (8) using an extrusion plastometer found values between 2.9 X 10' and 2.7 X 10* poises, depending on the driving force, for the apparent viscosity at room temperature of a partly crystallized aqueous system containing 63% potassium laurate. SUMMARYThe construction and operation of a new cutting-wire plastometer are described, suitable for use with substances of high viscosity which must be maintained at constant relative humidity as well as at constant temperature. Yield values, rate of flow at different velocities, and extent of elastic recovery can be studied with this instrument, thus permitting construction of curves which depict the complete rheological behavior of the material being studied.Experiments were carried out on asphalt and soap. The par-