The Ash Slagging/Fouling Characteristics Of Xin Jiang High Alkali Coal And It’s Blending Coal

The potential advantage of Xinjiang coal resources has been gradually well recognized with the increase of exploration and exploitation efforts on Xinjiang coal mine.As it is a newly found coal,Xinjiang Zhun-dong coal is notorious for its serious ash fouling slagging problems due to the high contents alkali mentals in it’s ash.Furthermore,the ash fouling,slaging characteristics as well as it’s deposit mechanism and it’s technical preventive measures have not be well understood until now.The rapid ash deposition rate and dense structure repeatedly cause unscheduled shutdown over 1-2 months.In light of this,most units have to blend with other kind of coals which incurs the increased operating cost and limits its utilization as a cheap fuel.In order to well understand the fouling,slagging characteristics of Xinjiang high alkali coal as well as it’s blending coal,lab-scale tests and pilot-scale test were used in this study.The transition characteristics of Na,K etc.alkai mentals as well as ash fouling slagging characteristics of Xinjiang high-alkali coal and it’s blending coals with different blending ratios were studied by using TGA,AFTs,SEM-EDX test etc.Furthermore,the ash fouling,slagging characteristics of Xinjiang high alkali coal as well as its blending coals were also studied in a 3MW pilot-scale test facility to simulate the real boiler combustion condition.The experimental results shown that the high content of Na,Ca and Cl in Xinjiang high alkali coal will cause serious ash fouling problems in the temperature range from 650℃ to 1000 ℃ in boiler.With the increase of low alkali coal’s blending ratio,the release ratio of Na as well as viscosity of ash of are being lighten.When the blending ratio is ranged from 20% to 50%,the blending ash are located in the eutectic region in the phase diagram,at that time the ash fouling tendecy was lighten,but the slaaging problem was becoming serious in the furnace.The results of this work can give a guidance for the boiler design,operating and coal blending when using that kind of coal.