摘 要
随着人们对能源需求量的日益扩大以及对环境质量要求的不断提高,作为近年来国际上发展起来的新一代高效、低污染的清洁燃烧锅炉,循环流化床锅炉得到了迅速地推广。由于循环流化床锅炉是一个多输入、多输出且各变量间相互关联的复杂控制对象,手动控制很难获得满意效果。采用计算机技术、自动化技术实现循环流化床锅炉综合自动化是目前过程控制的主要研究方向之一,是一项具有重要实际意义的研究课题。
本论文以烟台巨力异氰酸酯(TDI)有限公司循环流化床锅炉自动控制系统的开发为背景,结合目前流行的先进控制策略及方案,针对35t/h循环流化床锅炉的工艺特点,选用基于ABB公司AC800F控制器及相关卡件为硬件结构并辅以现场总线仪表实现集散控制。在此基础上,研究开发了集循环流化床锅炉除氧器水位及压力、汽包水位、主蒸汽压力、主蒸汽温度、炉膛负压、减温减压器温度及压力、过压报警保护及炉膛各参数超限报警保护等各环节运行于一体的过程控制系统。
由于循环流化床锅炉控制对象具有非线性、大惯性、大延迟的特点,常规闭环控制对此类对象难以获得满意效果,所以必须研究相应的先进控制策略。预测控制中的动态矩阵控制(DMC)算法有良好的跟踪性能和较强的鲁棒性,不仅能够直接处理带有纯滞后的过程对象,而且对大惯性过程对象有很强的适应能力。动态矩阵控制以对象的阶跃响应为直接模型,采用动态预测、滚动优化的策略,十分适合循环流化床锅炉的特点和要求。本论文研究了动态矩阵控制(DMC)算法的特点,将其应用于循环流化床锅炉床层温度的自动调节,并获得了满意的控制效果。
研究开发结果表明:该控制系统将DCS的优点和现场总线技术的优势相融合,同时又将经典的控制理论与预测模型算法相结合,提高了企业的自动化水平,节约了能源,改善了劳动条件。该项目的成功实施,为企业带来明显的经济效益和社会效益,有着巨大的现实意义。
关键词:循环流化床锅炉,过程控制系统,动态矩阵控制,OPC,集散控制系统(DCS)
ABSTRACT
With the increased demand for energy resources, it is necessary to study a new high-powered, low-pollution boiler. The Circulating Fluidized Bed Boiler (CFBB), has been developed rapidly and is used widely. As the CFBB is a complicated control system that has many input and output signals, it is hard to get a satisfying result with manual control. Nowadays, one of the main research items in integrated automation of CFBB is to achieve automation by applying computerized technology.
Based on the CFBB automation control system for a chemical plant in Yantai, the paper expounds on achieving the Distributed Control System (DCS) control project. This project is based on current, popular control strategies, the craftwork’s characteristics on CFBB, and the modules and PROFIBUS instruments from ABB company. Subsequently, the paper also narrates various control strategies such as main-steam pressure, main-steam temperature, modulate control system, sequence control system, and furnace safeguard system for CFBB.
The routine closed loop control system has issues. The control object for CFBB has traits for high inertia and delay. The Dynamic Matrix Control (DMC) can easily deal with these issues, as it has a strong ability to deal with inertia and well-slotted capability. DMC strategy adapts easily to the CFBB traits and demands. This paper stresses the arithmetic in DMC-PID, which is applied in controlling CFBB Bed temperature. DMC-PID provides perfect results after CFBB production.
The result of the research indicates that this system takes the advantages of DCS, PROFIBUS, and makes the classical control theory and arithmetic methods of prediction models work together. The system has enhanced the automotive qualities of plants, saved energy,and improved working conditions. At the same time, the successful application of the automation system has social and economic benefits for plants, but also the great realistic significance.
Keywords: Circulating Fluidized Bed Boiler (CFBB), Process Control, Dynamic Matrix Control (DMC), OLE for Process Control (OPC), Distributed Control System (DCS)