Online determination of heat transfer coefficients in sugar juice evaporation process

Abstract

In the sugar juice evaporation process, the temperature of incoming juice is raised to the boiling point, and the water content of the juice is reduced by evaporation. The main process outputs are raw sugar and molasses. Heat transfer coefficients are important parameters in the simulation of this process. Due to scaling, the values of heat transfer coefficients decrease over time, and cleaning must be carried after a certain period of operation. Although correlations of heat transfer coefficients and recommended values of scaling rates are available in the literature, there are uncertainties in their values. Therefore, reliance on these correlations to predict when an evaporator station requires cleaning may be in error. In this paper, a method of online determination of heat transfer coefficients and scaling rates using measured values of process parameters is presented. Testing of this method indicates that it can produce accurate values of heat transfer coefficients and scaling rates despite possible errors in input data.