【作者】 孔繁镍；

【导师】 何小阳；

【作者基本信息】 广西大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 广西是产糖大省，制糖工业是广西传统优势产业之一。为了有效地保持白糖的产量和提高产品的质量，必须想办法研究新技术、新方法，尽可能提高白糖的生产效率。本文的主要工作是基于蔗糖结晶机理模型的基础上研究蔗糖结晶过程控制的有效方法，以提高蔗糖结晶的速度、缩短煮糖时间、节约能源和提高产品质量。 传统上，大多数人认为煮糖结晶过程的控制是一个“黑箱”，因为目前煮糖结晶过程的控制操作都是由经验丰富的操作工人根据个人操作技巧和煮糖经验来控制煮糖过程。在理想条件下，煮糖结晶过程的控制应该使糖浆过饱和度、糖膏晶体含量这两个量保持在一定的范围内。糖液过饱和度必须足够大才能使晶种不断吸收糖分生长长大，但过饱和度值不能超出临界过饱和度值，如果过饱和度值超过临界过饱和度值，就会在糖浆中出现大量的小晶核。而晶体含量值过大，就会影响糖膏的循环速度，进而影响晶体的生长速率，从而扩大了糖产品的产品不均匀度。在此之前进行的很多研究工作主要是研究能可靠测量过饱和度的新仪器、新设备或者一些比较简单的控制方式(如常规PID控制)。 本文针对煮糖结晶过程的控制特点，把传统控制方式与智能控制相结合，运用模糊控制理论，设计模糊自适应PID控制器。在煮糖过 广西大学硕士学位论文程中根据实际糖浆过饱和度与设定糖浆过饱和度之间的偏差和偏差变化率，通过模糊推理及模糊裁决，实现对控制器参数的自适应调整，从而使实际输出过饱和度准确跟踪煮糖设定过饱和度，实现对煮糖结晶过程关键量一过饱和度的有效控制。 从控制器的仿真控制效果看，所设计的模糊自适应plD控制器可以有效地实现对过饱和度的控制，整个调节过程曲线比较平滑、无大的波动，比较符合实际煮糖结晶过程对过饱和度的工艺要求;并且对实际煮糖自动控制系统的设计也有一定的理论指导意义。从理论分析意义看，运用智能控制技术控制蔗糖结晶过程，实现蔗糖生产过程的自动化应该是可行的。更多还原

【Abstract】 Guangxi is the main sugar-produced province in China. The sugar industry is the traditional industry of Guangxi. To efficiently retain the sugar production and improve the quality of sugar, the new technology and new method must be investigated, so the sugar productive efficiency can be improved. This work demonstrates the efficient method of process control based on the batch raw sugar crystalliser model to improve the crystal rate and shorten the crystal time.Tradionally the control of the sugar crystalliser has been referred to as a "black box"where experienced operators use skill and past judgement to obtain satisfactory result. Ideally the control of a vacuum pan requires one to maintain two quantities(oversaturation and crystal content)within certain limits. The sucrose oversaturation must be kept high, thus motivating seed crystal growth, but no so high as to exceed thepoint of critical oversaturation. If this critical oversaturation is exceeded, an avalanche of small ,unwanted crystals nucleate from solution. If the crystal content value is too high, the natural circulation in the vacuum pan stalls, leading to crystal growth rate variations and resulting in expanding the product crystal size distribution. Previous work either concentrated on developing new instruments or alternatively to simply control the pan such as general PID control.According to the control characteristic of sugar crystal process, this work combines the traditional control method with the intelligence control method, employs the fuzzy control theory, design the fuzzy self-adaptive PID controller. The controller make the illation and verdict according to the error and error variety velocity between the actual oversaturation and the given oversaturation to auto self-adaptive tunning the parameters of the controller, so that the actual output oversaturation can accurately track the given oversaturation and the output oversaturation can be controlled efficiently during the sugar crystal process.From the effect of a series of simulations, the fuzzy self-adaptive PID controller can efficiently achieve to control the oversaturation and help to design the actual auto-control system of sugar crystal process, the regulating and controlling processing curve is gentle and smooth and the simulation effect is conformed with the oversaturation require to theactual sugar crystal process. From the theory, it is feasible to achieve the automation of sugar crystal process by employing the intelligence control technology.更多还原