Improved Model of an Intermediate Point Enthalpy Control System for Enhancing Boiler Efficiency

Abstract

Control quality of an once-through boiler’s water-fuel ratio (WFR) and main-steam temperature are heavily influenced by the control quality of the once-through boiler’s intermediate point enthalpy (IPE), and it is also related to the economic and stable operation of the a once-through boiler. In order to control the IPE in a better way and to increase boiler efficiency, an improved model of IPE control system was built in this paper, matlab/simulink is used to build the IPE control system model based on a 600 MW supercritical unit, and the mechanism model of the control object is built in the same time. The feedforward of the feed-water temperature is brought to this model to increase the control rate. The control method of amendments to the amount of coal and the control method of amendments to the amount of feed-water are combined by the means of fuzzy control to solve the problem of the contradiction of the responding speed of the IPE and the separation interface’s stability of the steam-water separator. The simulation results show that the improved control method has better control effect and higher boiler efficiency was obtained as well.