基于S-200PLC精馏温度控制系统设计.doc

基于PLC的工业精馏控制系统 摘 要 精馏是石油、轻工、化工等生产过程中，常常需要将原料、中间产物或粗产品中的组成部分进行分离，最常用的方法。精馏分离是根据溶液中各组分挥发度或沸点的差异，使各组分得以分离。精馏是化工过程中的核心组成部分，而对于精馏过程控制来说温度的控制是重中之重，剧烈的温度变化会导致分离组分离提纯度降低，对精馏的效率影响极大，甚至导致精馏塔无法正常运行以及设备的损坏。采用PID算法使PID控制更为灵活, 较好地满足了生产过程的要求。用WINCC上位机和西门子S7-200 PLC下位机组成一个稳定的温度控制系统，达到温度控制的目的，一旦温度设定值，，PLC发出信号精馏塔，使其增加或减小，使温度达到设定值。实际运行结果验证了PLC应用于精馏塔温度控制系统的可行性及精确性。 关键词：可编程控制器，温度控制，，PID控制 Industrial distillation tower based on PLC control system ABSTRACT Distillation is the petroleum, light industry, chemical industry production process, often need to be raw materials, intermediate products or the crude product components were separated, the most commonly used method. Distillation separation is based on the solution of volatile components in degree or boiling point difference, make each allocated to separate. Distillation is the process of the core components, and for the distillation process control, temperature control is the most important, sharp temperature change causes the separated group separation purity decreasing, the rectification efficiency greatly, and even lead to the normal operation of distillation tower and equipment damage. While the PLC has high reliability, easy programming, easy maintenance and other advantages, can be widely used in various control systems, so for the distillation process control special decided to use PLC to achieve temperature control for distillation system utility. In the rectifying tower temperature system is complicated in structure and accuracy requirements higher characteristic, adopts Siemens S7-200programmable controller PLC on system temperature system. As a result of distillation column temperature lag time constant and the inertia time constant was bigger, used to separate the single loop feedback control system, easy to cause larger oscillation, so the actual is used in cascade control and cascade control main controller adopts the integral separation PID control scheme. At the same time, the single para