Fouling Monitoring Of Heat Transfer Surface And Soot-Blowing Optimization Of Coal-Fired Boiler

Fouling and slagging on heat transfer surface have a significant effect on the economic and safety performance of the coal-fired boiler of power plant. At present, soot-blowing system of most power plants are operated on a fixed soot-blowing period, which usually based on operation experience or recommended scheme of boiler design specification. But this approach can’t meet the cleaning demand of heat transfer surface completely under various coal qualities. This work is aimed to propose a kind of optimized soot-blowing based on on-line monitoring of fouling and slagging on heat transfer surface.In this work, a 660MW boiler of DaTang Nanjing Power Generation is taken as research object. And the overall model of the boiler is put forward based on the traditional heat balance method model, in which all the heat transfer surfaces of the boiler is considered as a whole. The calculation process requires constant iterative in accordance with the flue gas direction based on the real time parameters of all the heat transfer surfaces. Then the ideal heat transfer coefficient and the real heat transfer coefficient are calculated, and the ash fouling condition of the heat transfer surface is characterized by the ash fouling factor.The data obtained by the overall model shows the real time fouling condition of the heat transfer surfaces as a kind of signal. However the signal is usually polluted by noise. The digital filter based on Fourier transform and wavelet filter based on wavelet analysis are designed. The wavelet analysis method can more clearly show the time-frequency characteristics of the boiler operating signal. Results show that the wavelet transform is a more efficient method in comparison with Fourier transform. In addition, wavelet packet analysis shows the high frequency details of the signals.To obtain accurate sample data for modeling, a series of sensitivity tests and model validation test have been conducted. The tests result verifies the accuracy of the overall model of the boiler. Then the economic model of individual heat transfer surface is put forward by using the mathematical model and the equivalent enthalpy drop method. The result shows that standard coal consumption decreases by 0.4855 g/kW·h。...