Research And Application Of Angle-tube Steam Boiler Automatic Control

As the gradual growth of industrial production, energy consumption and environmentdegradation are getting much worse. How to reduce energy consumption and pollutionemissions of every industrial production sectors has become a top priority in the industrialenterprise sustainable development strategy. In the current industrial production, as animportant energy conversion device, the boilers are applied in general but have drawbacks oflarge energy consumption and high emission. In the premise of safe operation, optimization ofboiler control system, increasing combustion efficiency and reducing harmful gas emissionshave not only economic significance but also social significance.In the thesis, a reconstruction project in a cigarette company 35T/h angle-tube steam boilercontrol system is treated as practice background. The production steam is used for tobaccocuring in the line. In the angle-tube steam boiler control system, the parameters of water level,furnace pressure, gas oxygen content and drum pressure are needed to control. In thefollowing tobacco-made production process, because of the extremely unstable of steamamount and large extent of steam flow in every change process, the frequent disturbances arecreated in the angle-tube steam boiler normal operation process and the control condition ismade complex slightly.The drum water level dynamic characteristic in the steam flow disturbance and suppliedwater flow disturbance, the drum water pressure dynamic characteristic in the burning ratedisturbance are analyzed in the thesis. For this series controlled object dynamic characteristicsand the control of drum water level, furnace pressure, flue gas oxygen content and drumpressure, water three impulse control scheme based on expert PID, furnace negative pressurefeed forward and feedback combined control scheme and fuel-air cross extent limitingcombustion control scheme are proposed. and the corresponding control algorithm are adopted. In actual engineering practice, due to the project, Siemens S7-300 series PLC isselected. Therefore, Siemens STEP7 software and the corresponding lower machine controlprocedures are used to write programs, as well as on-site commissioning. Now the productionhas put into operation, application results are satisfactory.