Wpływ wybranych parametrów na sprawność kotła CFB typu oxy

This paper presents a model of boiler operating in oxygen combustion technology. This is a CFB boiler for supercritical steam parameters 29MPa/600°C, operating at the power unit of gross electricity: 600 MW. The boiler is presented in two systems: with dried flue gas recirculation and humid flue gas recirculation. The methodology determining the thermal efficiency of the boiler and the assumptions for parametric analysis of two structural variants are described. During the analysis the impact on boiler efficiency of such quantities as the temperature difference between hot flue gas outlet and inlet cold water at the end of the water heater, and the ratio of excess oxidant in the combustion chamber, for both variants of the flue gas recirculation in the boiler. The impact of oxygen puroty in the oxididant on the efficiency of the boiler is also evaluated. Is shown, that the increase in efficiency with increasing oxygen concentration in the oxidant is negligibly small. It has been proven that essential to the efficiency value is the flue gas recirculation way. Flue gas wet recirculation increases boiler efficiency by approximately 1.5% compared to the dry exhaust gas recirculation.