Separations of multicomponent mixtures via thermal parametric pumping

This dissertation covers the separation of solutes from multicomponent solutions via direct mode thermal parametric pumping. Dilute solution separations were predicted from existing binary equations by assuming the existence of pseudo binary systems, each system consisting of one solute and the common solvent. Two systems, toluene-aniline-n-heptane and toluene-acetophenone-n-heptane with a silica gel adsorbent were used to experimentally demonstrate the separation. Experimental results were in good agreement with the mathematical predictions. For concentrated multicomponent solutions, the separation was demonstrated by the system, toluene-acetophenone-n-heptane on silica gel. The effects of mass transfer and nonlinear adsorption isotherms became significant and a numerical solution of the basic mass balance, rate, and equilibrium expressions was used to predict the product concentration profiles. These predictions were in reasonable agreement with the experimental results. Separation efficiency was increased by decreasing the bottom product rate and increasing the cycle time. Separation efficiency fell off sharply and the system appeared to be saturated as the total solute concentration reached 40 volume percent. The dilute solution (pseudo binary) theory was used to develop design equations for pilot plant and commercial systems. The parametric pumping assembly has the configuration of a multi-tube heat exchanger due to the necessity of instantaneous temperature changes between the hot and cold half-cycles. In addition to the main assembly, the requirements for auxiliary tanks, pumps, and instrumentation are outlined along with a process description for the operation of the entire system. Equations are also given for the required energies (steam, refrigeration, electrical) and the total energies compare favorably with conventional separation processes such as distillation. For the system studied, energy requirements were estimated at 600-900 BTU/lb. of bottom product for separation efficiencies of 50-100%. This was compared to distillation stripping and fractionating column separations where, for similar product purities, 310 and 1,250 BTU/lb. of bottom product are required