【作者】 随晶晶；

【导师】 赵学； 吴明亮；

【作者基本信息】 兰州理工大学 ， 机械设计及理论， 2011， 硕士

【摘要】 热电厂二氧化硫的排放严重危害了人类生存的环境,甚至还对人体健康产生直接影响。随着人们对生活环境质量要求的不断提高,对热电厂燃煤锅炉进行烟气脱硫也越来越为大家所重视。石灰石粉作为燃煤锅炉中主要的脱硫剂,其制备系统也成为了环保中重要的一部分。对于电厂来讲,高可靠性的石灰石制粉输送控制系统会减少脱硫系统停产的次数,使得维修费及停机检查损失费大大减小,保障了电厂的脱硫率,为环境保护工程作出贡献。本文首先分析了石灰石制粉生产线的结构,详细的介绍了各部分的设备组成形式及其功能,研究了整条生产线的工艺流程。根据工艺要求,结合对制粉生产过程的功能,给出了生产线各组成部分的总体设计方案。其次,从软、硬件两方面论述了石灰石粉生产线自动控制系统的设计过程,包括系统组成,部件选型,通信网络的确定,控制程序的编制和上位界面的设计等。为了提高自控系统的可靠性,选择了西门子公司的带有容错功能的S7-400H系列PLC进行了冗余设计,并使用了配套的STEP7编程软件和WinCC界面软件。最后本文对石灰石粉生产系统进行了可靠性分析,应用马尔可夫状态转移法分析、计算、对比了主控系统冗余前后的差别,同时,根据制粉系统的组成绘制了可靠性框图,由厂家提供的数据资料对制粉系统的工作可靠度进行了定量的计算。本文设计的控制系统对石灰石粉生产线控制效果很好,保证了热电厂脱硫的稳定运行,另外,对类似的制粉控制系统具有一定的技术借鉴作用。更多还原

【Abstract】 The emission of sulfur dioxide in thermal power plant is seriously damage the human living environment, even impacts human’s health directly. With the improvement of quality requirements on environment, we are paying more and more attention to flue gas desulphurization on the thermal power plant.As the main desulfurization agent of coal-fired boiler, limestone milling system has become an important part of environmental protection. For the power plant, high reliability control system in the limestone milling will reduce stopping frequency of desulfurization system, witch making the costs of maintenance and examination greatly. It ensures the desulfurization rate of the power plant, and makes contributions to environmental protection projects.Firstly, this article analyzes the structure of limestone milling production line, describes in detail every composition, function and the whole process.According to process requirements, combined with the milling function, overall control scheme of various components is given in this paper.Secondly, design process of the limestone milling control system is described from both hardware and software.It includs system components, parts selection, communication network, control procedures and interface design.In order to improve the reliability of automatic control system, Siemens S7-400H fault-tolerant redundant series PLC is selected to the redundant design.In addition, programming software STEP 7 and interface software WINCC are used to making the control system perfect.Finally, reliability theory is applied in the paper to analysis the reliability of limestone milling system.Markov state transition method is used to transition analyzing, calculating and comparing the difference of the main control system between before and after redundancy.At the same time, reliability diagram was drawn according to the composition of limestone milling sysem.This paper has caculated the reliability of milling system through using data provided by the manufacture.This control system of limestone power production line should work well to ensure the stable running of desulfurization in power plant. Additionally, it has certain technical reference to the similar milling control system.更多还原