A Developing Combustion And Air Distribution Monitoring System For BeiHe Power Plant

ABSTRACTFor the foursquare-distribution direct current firing implement, the distributing evenness of its air quantity and powdered coal quantity is very important to the safe and economical operation of power plant boiler. Well air distribution is the necessary condition to establish reasonable air kinetic operating condition and stable combustion. Moreover, the system of powdered coal conveying with primary air is the most important tache, whether the distribution of primary air is even or not directly relates to whether the distribution of powdered coal is even or not in all firing implement and nozzles, sequentially directly relates to whether it is hard to take fire, whether the fire is stable, whether there is coking and how about the heat efficiency of the boiler, hi addition, if there is jamming and deflagrate in the system of powdered coal conveying with primary air, severe safety accident can be resulted.This paper develops an on-line monitoring equipment of air distribution for the coal boiler of ChongQing BaiHe Power Plant. In the practical operation, there are three defaults in the former primary air distributing system: firstly, it is weak for the former system to receive and manage interrelated data. Secondly, the maintenance of the former system is very great. Thirdly, in the former system, a kind of sampling method is applied for the density testing of powdered coal, this method can cost relatively long time, and so cannot timely give the real density in the pipe of air and powdered coal.The new air distribution system has three characteristics. Its monitoring parameters are comprehensive, the data is applied adequately to realize the monitoring of various parameters, and, to make it more convenient, a kind of input method named touchscreen method is fixed in this air distribution system.In this system, mean velocity pipe is applied to transform the air velocity signal into pressure difference signal, and then the pressure difference signal is input into pressure difference transmitter to realize the transform of the pressure difference signal from non-electricity signal to electric current, and through the resistance in the corresponding sampling circuit the electric current is transformed into voltage signal; The thermocouple is used as the primary element to realize the transform from temperature signal to the voltage signal; Under the control of communication agreement module, diversified voltage signal is transported into computer by way of A/D conversion module, and then the monitoring software compiled beforehand is transferred to deal with all the voltage signals relatively, the result of which is conveyed to relative interface to display. For the monitoring of density of powdered coal, the paper put forward a kind of energy-balance method to realize the indirect monitoring of density, that is the computed temperature of primary air and that of powdered coal and that of the mixer of air and powdered coal is applied to compute the mean density of mixer of air and powdered coal according to energy-balance method.In the operation on site, this air distribution system can monitoring all the parameters above mentioned relatively perfectly, it is convenient to use and the maintenance of the system is easy. This air distribution system can play an important part in directing combustion adjustment and the safe and economical operation of boiler and unit.