【作者】 赵艳子；

【导师】 汤伟；

【作者基本信息】 陕西科技大学 ， 控制理论与控制工程， 2012， 硕士

【摘要】 磨浆是制浆造纸过程中不可或缺的环节，起着举足轻重的作用，它直接影响着成浆的质量和产量，生产效率以及资源能耗。盘磨间隙测量与控制是保证磨浆质量指标高低的一个重要标度，其作为磨浆设备的关键技术之一，一直深受国内外研究者的关注。然而，目前国内大多采用的接触式测量方法，只适合于测量初始盘磨间隙，而磨片磨损对测量的影响却并未考虑；而采用非接触式测量，虽然解决了上述问题，但对传感器的性能和材质要求特别高，且购买成本太高，一般很难达到。这也决定了直接测量方法虽然被普遍采用，但精度有待提高。本课题是在未央区科技计划项目（201001）“APMP制浆工艺优化及关键设备控制”资助下完成的。在了解磨浆过程工艺机理的基础上，经过分析与借鉴前人研究成果，针对盘磨间隙在线直接测量存在的精度问题，提出了直接测量与间接测量（基于支持向量机的软测量）相结合的方法，探讨盘磨间隙测量的新方向，本文主要工作及成果如下：1）盘磨间隙软测量数学模型研究由于磨浆过程的复杂性，使得盘磨间隙直接测量精度很难实现，文中提出直接测量与软测量相结合的思想。通过学习和分析，得出利用比较容易测量的二次变量(辅助变量)间接测出盘磨间隙，在该软测量模型中，主导变量为盘磨间隙，辅助变量为浆流量，浆浓度和电能耗。分别采用基于支持向量机和神经网络，以及基于poly核函数和RBF核函数两组对比进行仿真，探索适合盘磨间隙测量的软测量模型，仿真结果表明：基于RBF支持向量机更适合本研究盘磨间隙软测量模型的结论，进一步说明了支持向量机是基于小样本的，全局最优以及泛化能力强的学习工具。利用软测量得到的结果，对直接测量值进行修正，先算出软测量与直接测量在可行域下的差值，盘磨间隙的最终值为直接测量值加上所得差值。2）盘磨间隙测量技术工业实现研究本文结合宁夏美利纸业磨浆过程，设计了一种盘磨间隙测量技术在DCS控制系统开发平台上的实现方法。硬件开发选用西门子S7-400PLC作为平台，软件开发选用Step7和WINCC作为平台，上位机除了WINCC界面设计，还要实现与MATLAB的对接，将该测量技术嵌入到工业控制系统中，真正意义上实现理论实践相结合的思想目标。3）工作总结与未来研究展望将软测量技术应用在盘磨间隙的测量中，避免测量依靠硬件的局限性，真正实现盘磨间隙软测量技术的工业化途径，并为以后研究工作提供了新的方向，使课题更有意义地在线指导磨浆过程盘磨间隙的实时控制。更多还原

【Abstract】 The beating process is a necessary part of paper industry, and plays animportant role during paper making process, it also influences the quality oryield of pulp, production efficiency and energy consumption. Measuring andcontrolling the disc refiner gap is an important scale in guaranteeing the qualityindicator of pulp, as one of the key technologies of refiner equipments, it hasbeen taken more attention by researchers all over the world. However, at present,the method of contact disc refiner gap measurement is adopted mostly at home,it’s only suitable for measuring the disc refiner initial gap, without consideringthe influence of the plate wear, the method of non-contact disc refiner gapmeasurement can solve the above problem, but the requirement of sensorperformance and material is special high, the price of sensor is also expensive,it’s hard to meet the requirement. It also determines that the direct measurementhas been widely used, but the accuracy will be needed to improve.This subject is supported by the science and technology plan projects(201001) of Wei Yang area, named “APMP pulping optimization and the keyequipment control”. On the basis of introducing the refining process mechanismand analyzing other’s research results, aiming at the accuracy problem ofmeasuring the disc refiner gap directly, the combination idea of directmeasurement and indirect measurement(soft measurement) is proposed in thispaper, for further study at the disc refiner gap measurement, the main contentsand achievements of the paper are summarized as follows：1）Research on the mathematical model of soft measurement for discrefiner gapBecause the refining process is very complex, the accuracy of directmeasurement for disc refiner gap is difficult to achieve, the combination idea ofdirect measurement and soft measurement based on SVM (support vector machine) is proposed in this paper. Through studying and analyzing, it can usethe secondary variable measured easily to measure the disc refiner gap, in thesoft measurement model, the disc refiner gap is selected as leading variable, thepulp flow, pulp consistency and power consumption are selected as secondaryvariables. Two groups of contrast are been used to build the soft measurementmodel respectively, the simulation tools select between neural network andsupport vector machine, as well as between poly kernel function and RBFkernel function, the simulation results show that SVM based on RBF is betterthan NN (neural network) in modeling the soft measurement of disc refiner gap,it further illustrates that SVM is a study tool with small sample, global optimumand high generalization performance. The direct measurement values can beamended by using the soft measurement result, the differences between the softmeasurement and direct measurement value are worked out firstly in thefeasible region, the final disc refiner gap is the sum of direct measurementvalues and differences.2) Research on the industrial design about soft measurement technology ofdisc refiner gapAssociating with the beating process of Ningxia Meili industry, animplementation method of measurement technology for disc refiner gap isdesigned, which based on the development platform of DCS. S7-400PLC isselected as hardware development platform, WINCC and Step7are selected assoftware development platforms. It needs to not only design the WINCCinterface but only achieve docking with the MATLAB software on uppercomputer, so that the measurement technology can be embed into DCS controlsystem, the goal of combining theory and practice is realized indeed.3) Summarize the whole work and prospect the further studyThe soft measurement technology will be applied in the measurementprocess, therefore, the measurement limitations of relying on hardware can beavoided, the soft measurement technology of disc refiner gap will arrive at theindustrialization way, and provide a new direction for the future research work,the real-time control of the disc refiner gap will be realized by online guide.更多还原