Theoretical Study and Case Analysis for a Predried Lignite-Fired Power System

摘要

Lignite is a type of low-rank coal, which is uneconomically transported over long distances and does not efficiently generate electricity. As a result, lignite utilization and application is very limited;;lignite is mainly used as a low-level fuel that generates electricity inefficiently and can be distributed only in areas near lignite mines. With increasing requirements in efficiency and environmental protection, studying a new lignite-fired power system to improve the efficiency of direct lignite-fired power plants is very important. A rotary-tube dryer is mature drying equipment used in a pre-dried lignite-fired power system (PLPS). However, a comprehensive model approach on the influence of PLPS parameters on power generation efficiency and optimization has not been previously investigated. In the current paper, a PLPS theoretical model was developed based on basic thermal principles, and a case analysis was performed using this model as the theoretical foundation. Parameter influence was also calculated and analyzed. Results show that the PLPS theoretical model can evidently increase the efficiency of a conventional lignite-fired power system (CLPS) by approximately 1.87% when the condensate is sent to the de-aerator, and by 1.72% when the condensate is sent to the condenser at the calculation benchmark condition listed in this paper.