Energy and water conservation at lignite-fired power plants using drying and water recovery technologies

•Pre-drying and water recovery technologies were used to conserve energy and water.•The energy and water conservation potential were analyzed with reference cases.•The air-cooling unit produces water when the water content of lignite is high enough.•Influences of main parameters on energy and water conservation were analyzed. Lignite is considered as a competitive energy raw material with high security of supply viewed from a global angle. However, lignite-fired power plants have many shortcomings, including high investment, low energy efficiency and high water use. To address these issues, the drying and water recovery technologies are integrated within lignite-fired power plants. Both air-cooling and wet-cooling units with three kinds of lignite as feeding fuel were analyzed quantitatively. Results showed that energy conservation and water conservation are obtained simultaneously. The power plant firing high moisture lignite becomes more environmental friendly with higher power generation efficiency and a lower water makeup rate than the one firing low moisture lignite. And further calculation revealed that the air-cooling unit needs no makeup water and even produces some water as it generates power, when the water carrying coefficient is higher than 40g/MJ.