【作者】 王熙雏；

【导师】 何小阳；

【作者基本信息】 广西大学 ， 控制理论与控制工程， 2005， 硕士

【摘要】 煮糖工序是强非线性的工序。在这个过程中既有传热,又有传质,是一个复杂的化学和物理过程。从制糖工艺学中可知,在众多过程工艺参数中,母液的过饱和度对煮糖质量的影响最为显著,必须将这一参数控制在适当的范围内。 如果能够建立一个符合新理论的过程模型并进行仿真、控制,从而对设计一个适合的、性能良好、尽可能理想的结晶器,对优化煮糖工序的性能,以及控制蔗糖晶体的粒度分布,蔗糖产品的质量都是有重大意义的。本文针对当前糖厂生产现状,在总结先前研究成果的基础上,从蔗糖结晶的机理出发,结合当前蔗糖结晶动力学研究发展的新理论建立基于晶体生长机理的微分方程,以间歇式煮糖过程的物料平衡方程、晶体生长动力学方程以及矩平衡方程为基础,建立了基于与粒度有关的晶体生长理论的煮糖过程模型。本文采用工业生产中甲糖煮炼的初始条件进行模拟计算,并采用工业生产中甲糖煮炼的初始条件,对煮糖结晶过程进行传统的PID控制和非线性PID控制,从结果分析,所建立的模型具有较好的准确性,可以作为应用各种先进控制算法的基础。更多还原

【Abstract】 Crystallization is one of the key steps in the cane sugar processing. And sugar cryatallization with strongly nonlinearity and nonstationarity is a complicated physicochemical process. It is the step that produces the final product which must be monitored very closely as the quality of the final product determines profit. Crystallization occurs by boiling a sugar solution until it becomes oversaturated and crystals grow. Care must be taken not to exceed a critical oversaturation to prevent nucleation of new cyrystals, as these greatly affect the quality of the final product. So oversaturation must be controlled well.Since the crystallization process is complex , a model is required to understand the effect of operating conditions on parameters such as growth rate and crystal size. What’s more, the first and maybe the most important step in designing a perfect controller is to develop a model as accurate as possible, which is valid under a wide range of operating conditions.In this paper, a working model for the batch is developed and discussed. And the matlab coding for the working dynamic model of batch vacuum pan has been completed and tested. According to the control characteristic of sugar crystal process, a kind of nonlinear PID controller is designed. From the effect of a series of simulations, the nonlinear PID controller can efficiently achieve to control the oversaturation and help to design the actual auto-control system of sugar crystal process. From the results, we can see the model presented in this paper is validated.更多还原