Study On A Comprehensive Evaluation Model Of Pulverized Coal Flame Stability And Flameout

The accurate diagnosis of the stability of boiler combustion for the timely and reasonable combustion adjustments directly determine the safe and economic operation of the boiler unit, but the traditional techniques of boiler test for regulating combustion can only test the boiler efficiency, it can not to judge quantitatively the stability of combustion. In addition, Coal flame detectors of power plant are only used to recognize On-fire or Off-fire and critical fire, which it impossible to judge quantitatively the stability of combustion, can not to guide inject fuel oil for stabilizing combustion, and miss the optimum opportunity of injecting fuel oil lead to burning accident. Therefore, establish a comprehensive evaluation model of the stability of combustion to accurate predicate and diagnose the stability of combutiong is essential for the safe operation of power boiler.This paper analyzes the ignition modes of the tangentially fired boiler, we consider that if the entrainment of heat enough to the ignition heat before the jet of two adjacent angles intersecting, the ignition mode is entraining ignition. Otherwise, the ignition mode is adjacent igniting. The mixed boundary of the jet flow of adjacent angles was estimated with the characteristics of pulverized coal-air jet, the predicting model of the stability of combustion was established with the initial conditions of jet flow. The predicting model used the igniting distance as the stability index, and the effect of primary air velocity, primary air temperature, pulverized coal concentration, coal quality parameters, boiler load on the stability of combustion was analyzed.In addition, through analyzes state parameters of the combustion on the phase of the stable and unstable combustion to extinction, the results indicated that combustion status was changed, the furnace temperature, furnace negative pressure, flue gas oxygen content, carbon content of fly ash and flame images information have more significant changed, the diagnosis model of the stability of combustion was established with the different combustion state parameter. The input parameter of the diagnosis model is the combustion state parameter. Compare between the output parameters and normal conditions to judge the stability of combustion.Integrate the predicting model and the diagnosing model to establish the comprehensive evaluation model of the combustion stability. The comprehensive evaluation model not only reflects the theoretical results, but also reflects the accumulation of operating experience. It can greatly reduce the false positive rate. The output parameter of comprehensive evaluation model is stability coefficient. The combustion stability as a dynamic process was studied, rather than the traditional approach, which considered that the combustion was completed in an instant and stabled, and the combustion states are stable, unstable or stall condition.