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Determination of optimum vapor bleeding arrangements for sugar juice evaporation process
Author(s) -
Chantasiriwan S.
Publication year - 2018
Publication title -
journal of food process engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 45
eISSN - 1745-4530
pISSN - 0145-8876
DOI - 10.1111/jfpe.12616
Subject(s) - sugar , evaporator , evaporation , chemistry , boiling point , water vapor , thermodynamics , heat exchanger , food science , organic chemistry , physics
The sugar juice evaporation process consists of juice heater, evaporator, and crystallizer. The juice heater increases the temperature of diluted sugar juice from the ambient temperature to the boiling point. The evaporator removes most water content of diluted sugar juice. The crystallizer removes the remaining water content, yielding raw sugar as the final product. Since both the juice heater and the crystallizer require vapor bled from the evaporator, there are interactions between the three components. A model of interactions between the three components of the sugar juice evaporation process is presented in this paper. The model yields a system of nonlinear equations that, under some specified assumptions and conditions, consists of only two free parameters. This implies that there is a unique distribution of a given total juice heater surface when vapor is bled from the first two effects of the evaporator. In contrast, if vapor is bled from the first three or four effects, there are many possible surface distributions. It is shown that there is an optimum surface distribution when vapor is bled from either the first three or four effects of the evaporator that minimizes the steam economy. The optimum four‐effect vapor bleeding arrangement results in the largest steam economy. However, the two‐effect vapor bleeding arrangement produces a larger mass flow rate of processed sugar juice than either three‐effect vapor bleeding arrangement or four‐effect vapor bleeding arrangement. Practical applications This paper presents a mathematical model of a sugar juice evaporation process. Although one specific process design is under consideration, the model can easily be adjusted for a different process design. This model will be useful for analysis and optimization of the process. One optimization problem mentioned in the paper is the optimum allocation of a fixed total surface among the four heat exchangers of the juice heater, which is used to increase juice temperature to the boiling point before entering the quintuple‐effect evaporator. It is found that there are two different optimum surface allocations corresponding to the maximum rate of processed juice and the minimum amount of steam required by the process. Results of this paper should provide a guideline to a process designer in selecting the juice heater that will both satisfy the required heating duty and yield the optimum performance.