Thermal economic analysis of flue gas pre-drying lignite

Through coupling the high flue gas rotary drier together with the boiler system,the theoretical analysis model of high flue gas pre-drying lignite was established.The method to calculate the high flue gas flow needed for pre-drying and evaluate the unit economy was proposed.The calculation results show that,the coal consumption rate can be reduced by 1.39,2.10 and 0.96g/(kW·h),by using the flue gas pre-drying technology to lower the moisture of the lignite from 38%to 27%,20% and 14%,respectively.With a10 degree centigrade decrease in the exhaust gas temperature of the pre-drying lignite power plant,the coal consumption rate can be reduced by 1.3g/(kW·h).In order to achieve the optimum economy,the heat loss due to exhaust gas and the dryer heat loss need to be considered together to determine the level of predrying lignite.