This work was performed to investigate the response and stability of a jacketed kettle with internal heating/cooling coils and glasteel thermowell. This system was first analyzed mathematically by deriving transfer functions for each component and then combining all component equations together to give the overall system transfer function. The mathematical model was then checked by frequency response analysis of the system. Bode plots of the system were prepared and the effect of the thermowell was analyzed.
Nyquist plots of the system were used as the criteria for determining stability, and obtaining the open-loop gain necessary to give optimum closed-loop response. The system was found to be completely stable over the frequency range investigated.
Condensate throttling in the coil was the method used to control the kettle temperature during the frequency response tests. The advantages and disadvantages of this method of control are discussed.
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