Hiromi Shirai

Classification of Corrosion Behavior of Water Wall Tube Materials in Simulated Coal Combustion Atmospheres Including H2S

To obtain an indicator for evaluating the amount of corrosion of water wall tube materials in a coal-fired boiler, we investigated the effect of H2S and SO2 concentration on the amount of corrosion of Fe-2.25wt.%Cr-1wt.%Mo (STBA24) alloy at 773K in N2-CO-CO2-H2-H2O-H2S-SO2 mixed gases. As a result, it was clarified that the amount of corrosion and the scale structure were not affected by concentrations of H2S and SO2 when they were above 150ppm and 200ppm, receptively, at fixed PO2 and PS2. Therefore it appears that the amount of corrosion in this range of concentrations can be evaluated only from the correlation between PO2 and PS2. In contrast, under the condition of less than 150ppm SO2 or less than 200ppm H2S, the amount of corrosion was affected by the concentrations of SO2 and H2S. Therefore, it appears that the concentrations of SO2 and H2S are necessary to evaluate the amount of corrosion when the concentrations of SO2 and H2S are less than 150ppm and 200ppm, respectively. An indicator for evaluating the amount of corrosion was able to be proposed as a function of H2S and SO2 concentrations in coal combustion atmospheres. Introduction

Evaluation of Sulfide Corrosion Conditions in Pulverized Coal Fired Thermal Power Plant Boilers

Due to cutbacks in operational costs, many pulverized coal fired thermal power plant boilers have recently been operating under conditions of in-furnace reduction atmosphere enhancement. As a result, stronger in-furnace reduction atmospheres have led to sulfide corrosion. CRIEPI has conducted a study to clarify correlations between boiler operation conditions and sulfide corrosion, and to develop effective sulfide corrosion countermeasures. This report therefore describes experimental and theoretical results of research into evaluation techniques for a sulfide corrosion environment, along with actual applied results of evaluation techniques for a sulfide corrosion environment using an in-furnace of an active boiler.

Large-eddy simulation of pulverized coal combustion in swirling flow

Large-eddy simulation (LES) is applied to both a pulverized coal combustion and non-combustion field in a combustion test furnace with a practical advanced low NOx burner called CI-α burner, and investigated the effect to coal combustion on flow field and ignition mechanism. The results show that predicted flow field and coal particle behavior are in general agreement with the experiment. Coal combustion strongly affect flow filed. Primary air jet and swirling flow is enhanced by the burned gas expansion. Moreover, a recirculation flow formed by strong swirling flow is observed near the burner region and keeps stable coal combustion by transporting hot gas and increasing coal particle residence time.