Investigation of Condensing Heating Surfaces with Reduced Corrosion of Boilers with Water-Fuel Emulsion Combustion

Abstract

Using of condensing low-temperature heating surfaces in exhaust gas boilers allows to increase the economic efficiency of boilers and thermal power plants. Analysis of literary sources showed, that there were no quantitative data of the low-temperature corrosion intensity of exhaust gas boiler low-temperature heating surfaces while water-fuel emulsion combustion. Experimental investigations of corrosion processes of low-temperature heating surfaces in exhaust gas boilers with excess air factor in the range of 1.5…3.0 were carried out. The empirical correlations for dependence of specific metal mass loss on water content of water-fuel emulsion, sulfur content in output fuel and excess air factor α at wall temperatures below the dew point temperature of sulfuric acid vapor, which characterize the low-temperature corrosion intensity of condensation surfaces at different operating modes of exhaust gas boilers were received. For estimation of the influence of the quality of combustible fuel and its combustion regimes on the corrosion intensity, a computer simulation was conducted by using the statistical program package Statgraphics Centurion XV. These correlations show that the smallest values of corrosion intensity are observed at large values of water content in water-fuel emulsion of about 30%. The minimum values of exhaust gas temperature at the exit from exhaust gas boiler and of wall temperature are determined, at which the permissible speed of low-temperature corrosion at a level of 0.25 mm/year is ensured.