Heat transfer and hydrodynamics in preparative continuous annular chromatography (P-CAC)

Radial velocity profiles due to radial temperature gradients inside a prepa rative continuous annular chromatograph (P-CAC) are calculated and their in fluence on the separation performance is studied. A commercially available version of a P-CAC, which can be thermostatted from the inner cylinder, is investigated. The coupled equations for heat transfer and fluid flow are so lved with a finite difference method. As an example, the movement of a conc entrated and an infinitely diluted aqueous sucrose solution through a catio n exchange resin is examined. Calculations are performed for a desired oper ating temperature of 60 degrees C and different inlet temperatures. The inf luence of the velocity profiles on the elution profiles is first investigat ed for the simple case, where only temperature effects occur, and second in combination with mass transfer effects. A comparison with peak broadening in the isothermal case shows that the influence of mass transfer and temper ature is of the same magnitude.