基于PLC称重给煤机控制系统设计毕业论文.doc

中文摘要 随着火电厂规模和单机容量的扩大，给煤机在整个选煤系统中的作用越来越大，目前300MW 及以上的大机组的锅炉一般采用直吹式制粉系统，即一台磨煤机配备若干台给煤机，磨煤机的煤粉直接进入锅炉燃烧器燃烧。这样锅炉的給煤量就完全由给煤机决定，给煤机的控制性能就显得尤为重要。给煤机给煤量过多会加大皮带电机负荷，增加皮带磨损程度，增加设备故障发生几率，影响生产效率；给煤机给煤量过少又会降低生产效率，影响效益。称重式给煤机是一种可均匀、连续、定量地给煤到磨煤机中的设备，并且可以在给煤过程中对煤连续称重, 同时根据燃烧系统需求的煤量信号，随时调节给煤量。因此称重给煤机广泛适用于电力、冶金等各行业的工业锅炉的连续给煤。 可编程控制器PLC因具有高可靠性、易集中控制的优点，使其在工业控制中得到广泛应用。S7-200PLC和MCGS监控软件实现称重式给煤机监控系统的设计、调试等。通过上位机的监控画面，我们便可以对现场的机器运行状况一目了然。 本文重点介绍了可编程控制器在给煤机称重监控系统中的应用。分析了目前给煤机在电厂中的重要地位，根据给煤机控制系统的现有状况，详细阐述了改造后系统的工作原理及方式、控制系统的组成、PLC应用领域、发展方向以及如何设计梯形图在本文中都一一进行了介绍。并且经过模拟试验，证明了改造后系统运行达到了经济高效稳定的预定要求。PLC及上位机监控实现对给煤机的控制是现代化火电厂的需要。 关键词 称重式给煤机，可编程序控制器，上位机，监控系统 Abstract With the scale of the power plant and single capacity expansion, to plough in the whole selection the role of coal system is more and more big, Of the 300 MW and above the boiler generally USES the straight blowing pulverizing system, namely a mill is equipped with the number of coal feeder, mill coal directly into the boiler combustion burner. So the coal boiler is completely to the coal to decision, so to the control performance measurement coal are particularly important. the coal to give too much can increase the amount of coal belt motor load, increase belt worn degree, increase equipment failure risk,affects the production efficiency; To give coal stoker had measured and will reduce the production efficiency less, affect benefits. Coal is a kind of weigh can be evenly, continuous and quantitatively to coal to the mill equipment, and can be in the process of coal to coal for weighing, and according to the demand of the coal combustion system of signal, adjust at any time to coal quantity. To plow has setup convenient, environmental protection, and other very much, widely used in electric power, metallurgy industries of the industrial boiler continuously to coal. PLC programmable controller with high reliability, easy for the advantages of centralized control, so that in the industry control have been widely used. This design wi