Study On The Control Of Water-vapor System And Combustion System For Industrial Boiler

There is a considerable amount of industrial boilers in China, and it is necessary to keep the boilers in automatic control. The control of the water-vapor system and combustion system directly affects the safety and stability of the boilers and the efficiency of the production, though the two systems are the complex objects that difficult to control.This paper elaborated a Distributed Control System which using HC900 from the U.S. Honeywell Inc as controller and InTouch 10.0 from the U.S. Wonderware Inc to design the HMI, and the system was established for the three coal-fired steam boilers of GITI company in AnHui. We use HC Designer to do the HC900's configuration and design the control plan. The designed program can run independently, process the data collected from the boilers'field, then control the action of equipments. At the same time, the collected data were delivered to the HMI by Ethernet. The operator can also control the action of the equipments in manual way in HMI, and alter the parameters of automatic control according to the boilers in real time. The HMI offered the functions of alarm and history data too.The article focused on the research of the boilers'water-vapor system and combustion system, and mainly analyzed the drum water level and steam pressure, designed a control scheme for the boilers. In the control of the drum water level, according to the effects of water level which from the difference between water flow and steam flow, we used a line function generator to do pretreatment for the difference between the measured value and setting value, then a Three-Impulse control plan for drum water level was proposed. In the control of the steam pressure, taking into account that the boilers to be controlled are all the chain boilers which were unresponsive in combustion, we use steam flow which affected the steam pressure more directly as feed-forward parameters, and set its proportion in the control of the steam pressure to assist the adjusting. In addition, we briefly analyzed other items of the water-vapor system and combustion system, such as the steam temperature and the air volume and the furnace pressure, and gave some ideas and opinions.Now the control system has been applied in production, the results told the fact that the system was safe and stable, fast and accurately in data collection and processing, got good results in the control of drum water level and steam pressure, and the friendly, concise, vivid HMI was easy to operate. The system was recognized by all the boiler's staff.