According to the physical characteristics of coal, we can preliminarily judge whether the selected coal is easy to fouling and slagging. The physical properties of coal ash include the melting point temperature, ash viscosity, sintering temperature, slag characteristics of coal ash. Here we only discuss the effect of ash melting point temperature on slagging characteristics.

 Assuming coal ash deformation temperature T1, softening temperature T2.
The initial deformation temperature in the reductive atmosphere is a common indicator for predicting slagging tendency in the furnace.

Judging the slagging limit of coal by T1 temperature:
T1>1289 (° C) without slagging
T1=1108~1288 (° C) medium slagging
T1<1107 (° C) severe slagging

In the United States, the initial deformation temperature DT (equivalent to T1 in our standard) is used to predict the slagging characteristics of coal:
DT>1371 (° C) without slagging
DT=1093~1204 (° C) easy to slag

T2 is our standard test method for ash melting point weak reducing atmosphere softening temperature. The ash characteristics of 50 power coal in China are analyzed, and the empirical criterion is determined by the three - stage optimal segmentation method. details as follows:
T2>1390 (° C)) without slagging
T2= 1260 ~ 1390 (° C) medium slagging
T2<1260 (° C) severe slagging
The criterion has a resolution of about 65%.

The criterion for judging the slagging property of coal in Japan is T2:
T2>1230 (° C) low slagging
T2<1230 (° C) high slagging

The slagging condition of each furnace in 67 power plants was investigated. The classification criteria for the calorific value Qdw were as follows:
T2> 1230 (° C), Qdw = 8.5 ~ 27 (MJ / kg) without slagging zone
T2 <1230 (° C), Qdw> 12.6 (MJ / kg) Slagging zone