The migration rule of sodium and its blends during the combustion

as well as the main affecting factors

were studied by X-ray diffraction (XRD)

coal ash composition analysis

mathematical statistics and combustion verification of 100 MW boiler.In addition

a prediction method for combustion contamination of high sodium coal and its blended coal was provided.The results indicated that

the sodium in some high sodium coal will volatilize obviously when the ashing temperature is higher than 500℃

and the change of mass fraction of Na_2O and Fe_2O_3 has little effect on release rate of sodium in high sodium coal.CaO and Na_2O in high sodium coal and its blended coal ash can react with aluminosilicates at high temperatures

but there is obvious competition between them.When the mass fraction of CaO increases to a certain degree

the formation of sodium aluminosilicates will be inhibited.When the mass fraction of Na_2O in high sodium coal and its blended coal ash is less than 7%

the mass ratio of SiO_2 to CaO is larger than 4

indicating the high sodium coal and its blends are weak contaminated.When the mass ratio of SiO_2 to CaO is 2～4

the high sodium coal and its blends are medium contaminated.When the mass ratio of SiO_2 to CaO is below 2

the high sodium coal and its blends are strong contaminated.The smaller the mass ratio of SiO_2to CaO is

the stronger the ash contamination is.The accuracy and adaptability of the proposed method are verified by the boiler combustion test.