Otimização operacional do processo de cristalização da sacarose em leito vibrado

Abstract

Industrial production data shows that Brazil is currently the world\'s largest producer of cane sugar and the largest exporter of commercial sugar, which is an important element in Brazilian trade balance. This work aimed to study the sucrose crystallization in a vibrated bed crystallizer, in which was analyzed the influence of the following variables: supersaturation, vibration intensity and operation time through the execution of a design of experiments. The crystallizer in which the experiments were performed has a steam conical shape, is jacketed, manufactured in stainless steel and has as a vibration system two perforated plates separated by aluminum rings connected to the central axis of the device. The vibration energy comes from an electric motor in contact with a cam that transfers the vibration mechanical energy to the crystallizer axis, the vibration intensity was measured by a digital tachometer. In crystallization experiments were transferred to the crystallizer 280 mL of sucrose solution, prepared with commercial sucrose and distilled water in amounts indicated in experiment planning. In the crystallization process, it was used as seeds, sucrose crystals retained on sieve opening of Tyler 20 (0.841 mm), they were added in the crystallizing initiating crystallization. At the end of the process the crystals were separated from the solution and was analyzed the sucrose percentage productivity on the weight of the added seed, it was determined the average size of the crystals by sieving the material. Through statistical analysis, it was obtained the operating condition which maximizes the productivity and average crystal size, according to this configuration, the responses of production and average size were 162.14% and 1,466 mm. The results obtained in tests performed in triplicate were 163.12% for productivity and 1,481 mm for the average crystal size. In this optimal condition, the crystals growth during the crystallization process was studied in a similar process, employed in Pereira (1997), where the results obtained proved to be superior to the author. Comparing the operating conditions, the difference between the values suggests that this variation was provided by the high population of seeds and for determining the maximum operating conditional through the statistical analysis.