Authors: R. Laubscher, P. Rousseau
Year: 2020
Industry: Fossil Fuel Power Generation
Keywords: Use FSE, Boiler, Two-phase, Comparison
ABSTRACT
Co-simulation of the high-temperature heat and mass transfer processes in coal-fired boilers using CFD together with process-level models of the water/steam circuit is a promising approach to investigate off-design conditions. In the present work, a 1D discretized two-phase model of the water flows in the evaporator and radiative superheaters was developed. This was coupled with a detailed furnace combustion and heat transfer CFD model. The coupled models are used to investigate the impact of variable particle emissivity and scattering efficiency on the evaporator and radiant superheater process conditions, including the furnace steam generation rate and final steam temperature. The results are compared with the case where the radiation properties of the particles are assumed to be constant, thereby highlighting the importance of accounting for the variations in the particle properties throughout the process. The case study boiler is that of a real 620 MWe subcritical power plant firing coal with a high ash content (41 %wt). The results show that the constant property model results in a predicted furnace heat load that is 6.5% lower than the experimental value, while the conversion-dependent model is only 0.7% lower than the experimental value.