John Ingham

Effect of system properties on the performance of Liquid—Liquid extraction columns—II: Oldshue—Rushton column

Abstract Mean drop size, fractional hold-up of dispersed phase and axial mixing characteristics have been determined in a 72 mm diameter mechanically agitated extraction column of Oldshue—Rushton type, using the two liquid—liquid mass transfer systems, toluene—acetone—water and MIBK-acetic acid—water. As for normal conditions of packed column operation described in Part I, solute presence and the direction of mass transfer has a significant effect on mean drop size, fractional hold-up and to a lesser extent, axial mixing in the dispersed phase. Probably the most dramatic effect however is the manner in which solute transfer affects dispersed phase behaviour. Highly coalescing conditions with transfer from the dispersed to the continuous phase can make the column practically unoperable. As for the packed column, axial mixing in the continuous phase is unaffected except in so far as solute presence and direction of mass transfer affect the hold-up of dispersed phase.

Effect of system properties on the performance of liquid-liquid extraction columns—1: Packed column

Mean drop size, fractional hold-up of dispersed phase, and axial mixing have been determined in a 72 mm dia. packed column, packed with 8 mm glass Raschig rings, using the systems toluene-acetone-water and MIBK-acetic acid-water, in an attempt to assess the effects of the solute transfer processes on column operation. For the MIBK-system, where the packing size corresponded to the normal recommended conditions dp > dFC (packing size greater than the critical size of packing), solute presence and the direction of solute transfer was found to affect drop size, fractional hold-up and the axial mixing in the dispersed phase appreciably, in a manner which was consistent with either suppressed or enhanced coalescence characteristics according to the appropriate changes in solute system. For the toluene system, however, with the packing size corresponding to the condition dp < dFC, the drop behaviour was dominated by the action of the packing void spaces and mean drop size was independent of solute presence and direction of transfer. In both cases, axial mixing in the continuous phase was independent of solute effects, except in so far as these changes modified hold-up of the dispersed phase.

Effect of system properties on the performance of liquid—liquid extraction columns—III Mass transfer characteristics: Systems toluene—acetone—w

Abstract Liquid—liquid mass transfer characteristics have been determined for single freely rising drops and swarms of drops in both packed and Oldshue—Rush

Application of Digital Simulation Languages with Personal Computers in Chemical and Biochemical Engineering Education

Abstract Dynamic models in chemical and biochemical engineering are usually non-linear, and the resulting differential equations require numerical solution. Recently it became possible to run simulation software on microcomputers such as the IBM-PC or Apple-Macintosh. Comparison is made for three languages: ISIM and ACSL for the IBM-PC and STELLA for the Macintosh. For ISIM and ACSL model equations have to be set up and directly typed in. Output may be in a tabular or graphic form. With ISIM interactive variation of parameters (pump on/off; stirrer speed etc.) during the run is possible. The graphic capabilities are limited. STELLA is programmed using an interactive graphical model procedure. The model can be presented either graphically or as a list of equations. Graphic output possibilities are excellent. These methods were used both at the ETH and Bradford University in both university and short professional courses. Based on this experience it was found that computer simulation modelling methods greatly enhance the learning process.