Experimental Study And Mechanism On Drying And Blending Of Lignite

Coal resources is rich in our country, where lignite resources is relatively abundant,the proven reserves of lignite accounts for about17%of national coal reserves. With therapid development of economic, the high-quality coal including bituminous coal,anthracite.etc have been fully utilized, so lignite has become a major part in our countryenergy production and supply. Lignite is a lowgrade fuel of high volatile, high moisture,low calorific value, low ash melting point, resulting that it’s not conducive totransportation, storage, low efficiency of direct combustion, greenhouse gas emissionslarge and so on. So how to efficient, economy, comprehensive utilization of lignite andmake full use of lignite power generation is urgently needed to solve problems andimprove.This paper describes the research background, significance and research status,utilization analysis theoretical analysis and numerical combining simulation method ofthe lignite drying and blending, lignite elemental analysis, TGA experiments andisothermal drying experiment analysis, study a dry heat of lignite. Study lignite dryingtechnology, establish lignite drying process model, and calculated and analyzed themodel dryers and project examples of regenerative extraction steam drying lignite.Taking one plant600MW supercritical coal-fired boiler as the research object, take thenumerical simulation for blended lignite combustion process, and blended lignite werethermodynamic calculation in the partition period of furnace. Results show that thelignite coal sample moisture precipitation occurred mainly under180℃,15minutesbefore; the higher the drying temperature, the higher the degree of lignite drying, thefaster the drying rate. Use the superheated steam drying lignite, the higher steamtemperature, the lower the steam consumption necessary for lignite drying; the higher thelignite moisture content, the lower steam consumption necessary for lignite drying. Whenthe lignite blending share increased, the furnace temperature dropped, CO concentratio ofthe burner area elevated, CO2concentration in the hearth rised; after the lignite drying,furnace temperature increased, the CO concentration in the burner area decreased, theCO2concentration in the hearth dropped. Flue gas temperature and radiation heatingsurface heat load overall trend is consistent in each work condition, the burner sectionoutlet flue gas temperature and radiation heating surface is maximum heat load when theblending share of Lignite increased, the flue gas temperature and heat load of radiationheating surface decreased; After blending dry lignite, flue gas temperature and the heatload of radiation heating surface increased.