Stagewise mass transfer

It can be shown by simulation that a quasi-steady state can be reached for a fed-batch fermenter, where dX /dt=0 and //= l /V (Dunn and Mor, 1975). Since V increases, // must therefore decrease, and thus the reactor moves through a series of changing steady states for which //= I), during which Sj and ft decrease, and X remains constant. A detailed analysis of fed batch operation has been made by Keller and Dunn (1978). 

All three bioreactor modes described above can be simulated using the example BIOREACT. 

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Stagewise mass transfer processes 622 Standard orifice meter 249... 

Fig. 1.25 shows a countercurrent stagewise mass transfer cascade and the resulting staged profile of the two streams, owing to the mass transfer between the streams. 

The principle of the perfectly-mixed stirred tank has been discussed previously in Sec. 1.2.2, and this provides essential building block for modelling applications. In this section, the concept is applied to tank type reactor systems and stagewise mass transfer applications, such that the resulting model equations often appear in the form of linked sets of first-order difference differential equations. Solution by digital simulation works well for small problems, in which the number of equations are relatively small and where the problem is not compounded by stiffness or by the need for iterative procedures. For these reasons, the dynamic modelling of the continuous distillation columns in this section is intended only as a demonstration of method, rather than as a realistic attempt at solution. For the solution of complex distillation problems, the reader is referred to commercial dynamic simulation packages. 

Chapter 3 concerns the dynamic characteristics of stagewise types of equipment, based on the concept of the well-stirred tank. In this, the various types of stirred-tank chemical reactor operation are considered, together with allowance for heat effects, non-ideal flow, control and safety. Also included is the modelling of stagewise mass transfer applications, based on liquid-liquid extraction, gas absorption and distillation. 

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