Simulation research on the off-design characteristics of flue gas pre-dried lignite-fired power system-inuence of power load and lignite moisture content

The whole-system boiler-turbine coupling simulation models of the conventional lignite-fired power system (CLPS) and the flue gas pre-dried lignite-fired power system (FPLPS) were developed in the present work. A 600 MW unit was taken as reference case to examine the influence of power load and lignite moisture content on the energy saving and water recovery capability of the FPLPS. The FPLPS is found to have remarkable energy saving and water recovery potential compared with CLPS. The standard coal consumption rate can be decreased by 9.91 g·(kW·h)^-1 at THA condition, in which the lignite moisture content is reduced from 39.5% to 9.82% and the ambient is warmed to 55 ℃ by the dryer exhaust. Besides, 12.8 t·h^-1 water can be recovered from raw lignite. When the power load decreases from THA to 50% THA the energy saving reduces to 9.30 g·(kW·h)^-1 while the water recovery rate reduces to 7.3 t·h^-1. With a 10% decrease in lignite moisture content, the energy saving is reduced by 1.25 g·(kW·h)^-1 while the water recovery rate is reduced by 3.8 t·h^-1.