A concept of critical particle size of pulverized coal which can be fully burnt away under certain conditions has been put forward

and an unburnt away rate under different distribution of pulverized coal fineness being obtained through calculation on the basis of particle size distribution behavior of the pulverized coal and the critical particle size under burnt away condition of the pulverized coal

the influence of critical particle size during burnt away of the pulverized coal

the fineness of pulverized coal

and the volatile matter content etc.upon the unburnt away rate being analysed.Analysis shows that the calculated value from emperical formula of the volatile matter content is somewhat greater than that of the economic fineness of pulverized coal for hardly burnt coal with low volatile matter content;the calculated value from emperical formula of volatile matter content is somewhat smaller than that of economic pulverized coal fineness for fuel coal with Vdat35% and more;the calculated value of fineness for pulverized coal from emperical formula of volatile matter content is within the range of economic fineness of pulverized coal for other fuel coal

however

the economic fineness value of pulverized coal has to be determined through test.