Browsing by Author "Mtalam, Kassim Ismail"

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    Design and implementation of a real-time computer-based monitoring system for TBL fermentation plant
    (University of Dar es Salaam, 2004) Mtalam, Kassim Ismail
    The fermentation process at Tanzania Breweries Ltd is a type of batch (stirred) tank reactors. In general, there is no steady state in a batch cycle, and therefore no “normal” conditions at which controllers could be tuned. Dynamics of the batch process vary with time; thus, the process variables, the process gains, and the time constants also vary during the batch circle. In addition, there are the problems of runway reactions and batch-to-batch product uniformity. Runaway reactions occur in exothermic reactions like the fementation process, in which an increase in temperature speeds to the reaction, which in turn releases more heat and raises the temperature further. In order to counter this positive feedback cycle, highly self-regulating coolong systems are required. The present control system, based on a PLC, is not good enough as far as temperature control is concerned and the manual operations involved. A computer- based Software (S/W) has been developed to improve the performance of the control system, in which a computer is linked to the PLC via a serial cable, such that the PLC becomes the master controller and the computer the secondary controller. The software solution enables accurate temperature control and renders the manual operations redundant. It also facilitates addition of useful functions like data logging, report production, remote process monitoring and visualization to the integrated into the control system. The software, developed in Visual C++ for Windows, was successfully tested in a real-time emulated environment, whereby the computer was used to emulate the PLC and the fermentation process. Tests and implementation on the real plant awaits availability of a PLC for further experimentation.