Investigation On Corrosion Behaviors Of Downstream Components Of Power Plant Following The WFGD

Sulfuric acid vapor from power plant firing fuel can cause low temperature corrosion of the co-components, once the temperature of flue gas is below the acid dew point. The application of WFGD for the remove of SO2 has an effect on the corrosion. The problem will be serious along with the more and more applications of WFGD in China. Based on this background, the basic properties of corrosion of the downstream components after the WFGD were systematically investigated on CFD (Computational Fluid Dynamics) software platform. At the same time, the erosion-accelerating method was developed to study the corrosion characteristics of the downstream component's materials according to the simulation data. Besides the experimental research, the simulation and calculation for the research objects were performed.This paper first reviews the main acid dew point calculation formulas at present. Based the flue gas composition of typical fuels, the acid dew point was computed. According to the results and the contrasts between the statistic and the experiment data of the literature, the effects on the acid dew point of the WFGD were analyzed. The following results are obtained from the study: the lower limit of acid dew point is determined by the Haase & Borgmann formula, and the upper limit by Verhoff & Banchero formula. The power function including the experiment constants (B) was recommended to determine the exact acid dew point of the flue gas.The thermodynamics theory and the modified fugacity equation were used to predict the condensate concentration. Numerical simulation of the condensate process of the downstream components was performed on FLUENT software platform. Modified fugacity theory was applied to determine the concentration of the sulfuric acid vapor above the condensed sulfuric acid, which was the boundary condition of the FLUENT numerical model. The deposit rate of the condensed sulfuric acid was quantitatively predicted under the various conditions. The following results are obtained from the study: the condensate concentration is decreased with the increasing of the water vapor concentration and the decreasing of the wall temperature after the WFGD. The deposit rate of the sulfuric acid is essentially controlled by the sulfuric acid vapor concentration of the flue gas. The reduction of sulfuric acid vapor concentration of the flue gas after the WFGD cause the decreasing of the acid deposit rate. At the same time the flow velocity of flue gas has few effects on the deposit rate and the deposit rate is decreased along the flue gas flow. The simulated data is in a good accordance with the experiment data of the literatures before. The model can be used to predict the corrosion environment of the downstream components.The erosion-accelerating method was developed. The corrosive characteristics of concrete of the power plant chimney were studied in high SO2 concentration. The main environment factors affecting neutralization were analyzed as well, i.e.SO2 concentration, relative humidity, temperature. A new model of concrete corrosion under combined action of durability factors including temperature and humidity is established based on experimental results. The following results are obtained from the prediction: the main control corrosion factor of the concrete of power plant chimney is sulfuric acid condensate. The gas phase corrosion of SO2 is slight.Based the predicted corrosion environment before, the erosion-accelerating method was developed. The corrosive characteristics of concrete of the power plant chimney were studied in sulfuric acid mediums...