Technical And Economical Research On Drying Lignite For A 300MW Lignite Power Plant

The lignite with high moisture content,high ash content,low calorific value,if directly used for power generation will lead to power plant boiler and power plant net overall efficiency decreased.This paper introduces the application situation of lignit e in China in the field of power generation,Study on the drying methods at home and abroad more mainstream and equipment,and taking the tube dryer as the research object focuses on the structure of tube dryer and drying principle,built the heat balance calculation model for tube dryer of lignite,the calculation method of coal quantity balance and gas balance in the drying process is discussed,and the heat balance and the heat transfer area of the equipment are calculated.In the case of raw lignite output 200t/h,36.32% of the original moisture and 25% of dry coal as an example,calculate the balance heat pipe,by calculating the drying process required for heating steam,with wet air,dry coal,dehydration,main technical data of equipment heat transfer area.In this paper,a new 300 MW Inner Mongolia lignite fired power plant as an example,the extraction steam tube dryer is used as the heat source of furnace before drying.For drying lignite and water 36.32% water 25% raw lignite this two kinds of fuel for boiler efficiency calculation,the results show that: In the case of 894.43t/h evaporation,with a boiler burning water 36.32% raw lignite drying lignite fired boiler efficiency than 25% moisture increased from 89.88% to 92.21%.In addition,for the same pumping parameters,the drying capacity of steam at different drying depths was calculated and compared,the results show that: As for the same heat source parameters,the less water is removed from the raw lignite with the same moisture,the more steam required by the unit dewater.In addition,through calculation the lignite of 300 MW unit is 36.32% of original moisture content,the minimum moisture content of lignite after steam extraction is 32.5%;and the relationship between dry coal water and boiler efficiency are analyzed by calculation and comparison.This paper introduces the technological process of the furnace steam drying process.Comprehensive analysis of the whole furnace drying equipment procurement,investment construction and system operation and maintenance costs,for the 300 MW unit,the total investment of the steam extraction drying system is about 90 million Yuan.Technical and economic comparison of lignite power generation with moisture content of 36.32% and moisture content of 32.5% respectively,the results show that: In the production of electricity 0.4 Yuan /kWh,production water price 1 Yuan / ton,only in the raw lignite prices rose to 1221 Yuan / ton,the balance can be achieved only in front of the furnace steam drying system for investment operations.