Thermal Evaluation of Shell and Tube Heat Exchangers in the Sugar Industry: Case Study

Sugar is one of the most important commodities of the world, this high production makes the sugar factories have a complex energy integration of the process. One point of energy consumption is the heating of sugarcane juice in heat exchangers. To analyze this point, the thermal design of five boxes of the shell and tube exchangers of a sugar plant was evaluated in terms of the outlet temperature of sugarcane juice, overall heat transfer coefficient, fouling resistance and pressure drop. It was considered actual process conditions and service requirements, as well as equipment characteristics. In combinations of the exchangers was reached the operation minimum temperature of the sugarcane juice (105 degrees C). It was estimated that production could be increased by 24% if the outlet juice temperature was reduced to 101 degrees C. The clean and dirty overall coefficient varied between 2364 and 3462 kcal/hm(2) degrees C and 114 and 158 kcal/hm(2) degrees C, respectively. Fouling resistance ranged between 0.0061 and 0.0084 hm(2) degrees C/kcal, about 10 times more than the recommendations. Despite the fouling resistance, the pressure drops of the exchangers are within the limits of the specifications, but it can still be increased in order to improve the heat exchange. The results are discussed and commented, and possible immediate solutions for improvement are recommended. The data obtained serve as a reference for comparative purposes and future simulations of the process.