Abstract:
The dynamic model and control of an Agitated Thin Film Evaporator, AFTE, for concentrating orange juice was studies in this research. Like many other distributed parameter processes, an improvement in the control of an AFTE can enhance the process economics by reducing energy consumption and raw material. The focus of this study is on ATFE which are widely used in the Thai food industry. The major of goals for this research is to develop an appropriate control structure for an ATFE system for concentrating orange juice. Experimental measurements were obtained fiom a pilot plant ATFE. Step changes in feed flow rate, feed concentration, feed temperature, steam pressure and Vacuum pressure were made. The output variables such as product flow, concentration and temperature were measured. Dynamic First Order Plus Time, FOPDT, model were developed. The nonlinear dynamic behavior of the ATFE system model were solved using Control Station or Matlab Software. Various control configurations will developed includes: feedback, feedforwrad, feedback-feedforward , cascade and multivariable control. PI controller in feed back control is good enough because it can eliminate an offset. Although more complex control strategies such as feed forward, feed back or multiloop controlresult in a reduction in the standard deviation it is felt that the " const- benefit" relationship favours the PI controller.