Fuzzy Control Applications Applied To CFBB System

Circulating fluidized bed boiler has the advantages of widely fuel-adaptive, high combustion efficiency and low nitrogen-oxide emissions, makes its applications especially wide. However, it is very hard to build a precise mathematical model for circulating fluidized bed boiler because of the complicated control features, multi input/output, large delay of this system make it hard to control the circulating fluidized bed boiler.This paper will take a further analyze on the circulating fluidized bed boiler combustion system. The difficulties of combustion system control will be presented. Transfer factors of boiler bed temperature and main steam pressure are also deduced base on mechanism modeling. Then the calculating is performed about the boiler bed temperature and main steam pressure coupling relational degree to confirm the corresponding relations of all variables in order to realize the coupling of the bed temperature and the main steam pressure. Based on the coupling, the combustion system decoupling is performed by the static decoupling algorithm and fuzzy feed-forward decoupling algorithm. The simulating result shows the fuzzy feed-forward decoupling control takes fine effect on the combustion system decoupling.The fuzzy self-adaptive PID controller operated without precision mathematic model of the controlled objective, which suits for large-delay non-linear system can meet the requirement of combustion system. So in this paper, combined of the both advantages, the coal feeding is controlled respectively depending on the boiler bed temperature and main stream pressure. Result of simulation shows both two controllers working is perfectly meet the expectation, also, meet the requirement of the stabilities and real time feature.In this paper, the Honeywell EPKS controller system is applied to the boiler control system against the characters of circulating fluidized bed boiler. The hardware configurations are also designed, and mainly the control policy is designed; the simulation of fuzzy decoupling control applied to control policy is performed, the result of the simulation indicates the fuzzy decoupling control works well on decoupling of the combustion system.