Application of fuzzy control theory to direct-heating furnace control system

On the basis of bias-flow analysis and the tackling method, a control scheme is present to resolve the bias-flow problem. Three fuzzy controllers are built, based on the three pipes´ absolute temperature-difference as the input, the openness of the valve as the controlled object. After realizing this control scheme, the problem of bias-flow is resolved satisfactorily. The coked pipes are burned once a year, and almost no-coking occurs. We have been using this control scheme up to now for seven years and there is no need to replace the heating-pipes at all. The new design method of discrete fuzzy controller presented in this paper can also resolve the bias-flow problem in other fluid distribution control systems.