Effects of fine ash particles and alkali metals on ash deposition characteristics at the initial stage of ash deposition determined in 1.5Â MWth pilot plant tests

► Fine ash particles and alkali metals affect on the initial stage of coal ash deposition. ► Their effects on heat transfer have been evaluated in 1.5 MWth pilot plant tests using a test probe. ► Decreasing rate of heat flux through the probe represents slagging potential. ► A regression analysis of heat flux data was done considering fine particles and alkali values. ► Calculation using a regression equation agreed well with experimental data.