Energy Analysis of Low-Rank Coal Pre-Drying Power Generation Systems

Abstract

Low-rank coal (LRC) is widely used for power generation in many regions of the world. However, due to the high moisture content of LRC, the overall efficiency of LRC-fired power plants without a pre-drying system is relatively low. Studies show that the overall efficiency can be improved by pre-drying the coal, and the fluidized bed drying technique is found to be a desirable choice because of its high drying rate, high processing capacity, and low maintenance cost. In this paper, two novel, fluidized-bed, LRC pre-drying systems were integrated into a 1000 MW LRC-fired power plant. Superheated steam and hot air were used as the fluidizing medium. Models for each component of these power generation systems were developed based on material and energy balances. The performances of these power plants were calculated under the typical operating conditions, and parametric analyses were also performed to evaluate the effect of operating parameters. The power generation efficiency is found to increase remarkably with a properly operated LRC pre-drying system.

Keywords:

• Coal drying
• Fluidized-bed drying
• Heat recovery
• Low-rank coal
• Power plant

ACKNOWLEDGMENT

The financial support from Shanghai Boiler Works Ltd. for this research is gratefully acknowledged.