| The sugar industry is our tradition industry, and its sugar output has been on the fourth in the world in 2006. Yunnan is a big sugar producing province, there are many sugar factories and workers, which play important roles in the local economy. Sugar boiling is one of the important processes, but sugar boiling process of most factories in Yunnan, such as the JinKe sugar Ltd, co. in Yunjiang, is depending on the experience control, which has seriously affected the quality and efficiency of the sugar boiling.Therefore, it is necessary to realize automation of the sugar boiling process.Two main conclusions have beeen summarized in the analysis of domestic and foreign sugar boiling processes:one is that the sane sugar viscosity has a obvious relationship with supersaturation coefficient and crystal content which are two important parameters in sugar boiling processes, however, the common used refractometer and the electric conductivity meter only reflect one parameter, so taking sane sugar viscosity as control parameter displays a unique superiority. The other is that experimental research about the rheological behavior of sane sugar is seldom found on the domestic study papers, and the technology of viscosity sensor for online examination is weak, but these two aspects are the foundation of viscosity control. Therefore, the questions in view of the above presentation was analyzed in this paper.Using the digital viscometer, the rheological behavior of armor sane sugar was experimentally researched which is taken from the Yunjiang JinKe sugar Ltd, co. in Yunnan, also, the affect of temperature,concentration and shearing rate on the rheological behavior of sane sugar has been discussed.In the scope of test condition, the experimental results showed that sane sugar become pseudo-plasticity fluid and take on thixotropy. Its viscosity reduced quickly with the rise of temperature, however, the viscosity reduced slowly when reached to 55℃. Its viscosity reduced quickly with the rise of shearing rate, however, the viscosity reduced slowly when shearing rate reache to 10 s-1. When temperature is certain, viscosity increased and non-Newton was more remarkable along with concentration being increased. And when concentration is certain, if concentration was much bigger, the rheological behavior was effected by temperature much greater; if temperature was much higher, non-Newton was less significant.Through experimental data's return process, consistency index K and rheological property index n changes along with the temperature changes, index model was suitable for concentration lower than 77.30°Bx, otherwise suitable for multinomial model. Rheological property index n changes along with the concentration changs, which uses the multinomial model. Consistency index K with the changes of concentration is suitable for the geometric model.Viscosity measurement is a prerequisite for viscosity control, based on the rheological behavior of sane sugar, a single-cylinder rotary viscosity sensor for online examination was designed in this paper. The sensor includes five parts:the constant speed part of stepping motor, the torque part of sleeve and cantilever elastic unit, the torque measurement part of two increase type rotary encoder, the sensing part of rotor and the support part of foundation, and the sensor is fit for on-line measurement installed on the vacuum pan.The armor sugar boiling process includes five stages:boiling water, reorganization crystal, crystal growth, armor washing and concentration. Samples were taken from all key operation points of sugar boiling process that operated by skilled worker, and then a curve that viscosity fluctuated with time in the sugar boiling process was drew, which is composed by different slope of the curve in the each stage, so it prove that taking viscosity as automatic control parameter is feasible. Finally, on the basis of the viscosity and the time parameters, the control method of the sugar boiling process was proposed. |
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