Batch processes multiple stages

The purification of value-added pharmaceuticals in the past required multiple chromatographic steps for batch purification processes. The design and optimization of these processes were often cumbersome and the operations were fundamentally complex. Individual batch processes requires optimization between chromatographic efficiency and enantioselectivity, which results in major economic ramifications. An additional problem was the extremely short time for development of the purification process. Commercial constraints demand that the time interval between non-optimized laboratory bench purification and the first process-scale production for clinical trials are kept to a minimum. Therefore, rapid process design and optimization methods based on computer aided simulation of an SMB process will assist at this stage. 

In comparison to batch processing, this process operates at the final concentration with associated low fluxes. The use of multiple stages where the retentate outlet from one stage feeds the next allows successive systems to operate at different fluxes and will improve membrane productivities. 

Semicontinuous production processes can be described in a similar way as batch production processes by adding a duration information to a material flow. This makes it possible to handle the overlapping of independent process orders over multiple stages in campaign planning and semicontinuous production planning. 

Seeded emulsion polymerization can be used with batch, semi-continuous, or continuous polymerization to give the desired value of N, In batch or semi-continuous emulsion polymerization, seeding ensures batch-to-batch reproducibility of the final particle size in continuous emulsion polymerization, it ensures the reproducibility, not only of the final particle size, but also of the conversion of the exit stream. Seeded emulsion polymerization is equally adaptable to emulsion homopolymerization and copolymerization. Moreover, two-stage or multiple-stage polymerizations can be used to produce core-shell latex particles the variation of the process type---batch, semi-continuous, continuous----as well as the para-... 

The available data from emulsion polymerization systems have been obtained almost exclusively through manual, off-line analysis of monomer conversion, emulsifier concentration, particle size, molecular weight, etc. For batch systems this results in a large expenditure of time in order to sample with sufficient frequency to accurately observe the system kinetics. In continuous systems a large number of samples are required to observe interesting system dynamics such as multiple steady states or limit cycles. In addition, feedback control of any process variable other than temperature or pressure is impossible without specialized on-line sensors. This note describes the initial stages of development of two such sensors, (one for the monitoring of reactor conversion and the other for the continuous measurement of surface tension), and their implementation as part of a computer data acquisition system for the emulsion polymerization of methyl methacrylate. 

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