Theoretical study on pre-dried lignite-fired power generation system

A theoretical economy analysis model for a lignite-fired power generation system was established on the basis of the equivalent heat drop method. The energy saving condition of lignite pre-drying with steam of the reheat system was stated. A case study on a 600 MW power generation system was conducted to analyze the factors influencing thermal efficiency. The results show that the system can reduce the coal consumption rate by 11.21 g·(kW·h)^-1 under the rated condition. When the boiler exhaust temperature increases by every 10°C, the coal consumption rate will decline by about 1.5 g·(kW·h)^-1 because of lignite pre-drying. The coal consumption rate will decrease by about 3.3 g·(kW·h)^-1 when every 0.1 kg more water escapes from 1 kg lignite. The thermal economy rises with the decrease in the steam amount used for 1 kg moisture to escape from lignite, and the influence on the thermal economy is more obvious when the lignite is per-dried better.