In the context of CO2 capture and storage, the oxyfuel technology provides a promising option applicable in centralised power production plants. This technology implies combustion of fuel with pure oxygen instead of air. In this way, the flue gas consists mainly of CO2 and H2O, since the N2 is absent. However, combustion with pure oxygen results in very high flame temperatures and cold flue gas recirculation is required to moderate the temperatures.
The focus of the work presented in this paper is to apply the oxyfuel combustion technology in a green-field lignite-fired power plant and provide the basic design characteristics of the oxyfuel boiler compared to a reference typical Greek power plant. Due to combustion with pure oxygen and the absence of nitrogen in the flue gas composition, there is a different design of the heat exchanging surfaces of the boiler compared to the conventional boiler.
The input data for the heat exchanging surface calculations consists of results from thermodynamic simulations for both the conventional power plant and the oxyfuel power plant. A comparative view regarding the basic design characteristics for both boilers (i.e. conventional and oxyfuei) is provided.
The dominating factors affecting the dimensioning of the oxyfuel boiler are the high concentrations of CO2 and H2O in the flue gas - resulting in higher radiative heat transfer - and the different flue gas mass flow, compared to the conventional boiler.