What is the ash softening temperature and slagging property of coal?

What is the ash softening temperature and slagging property of coal?
Ash is a mixture of various inorganic minerals, which will soften and melt into liquid state when heated. Different ash has different softening temperature and melting point. Ash with low softening temperature and melting point may be viscous or molten in the combustion chamber, thus hindering air circulation and affecting the normal progress of combustion or vaporization

Generally, the temperature at which the ash starts to soften is called the deformation temperature, the temperature at which the ash starts to soften is called the softening temperature, and the temperature at which the ash melts in a fluid state is called the melting temperature. There is a definite relationship between softening temperature and melting point. According to the softening temperature of ash, ash can be divided into four types: fusible (melting point less than 1100 ° C), low melting (melting point between 1100 ° C and 1250 ° C), high melting (melting point between 1250 ° C and 1500 ° C) and refractory (melting point greater than 1500 ° C). The ash softening temperature of Chinese coal is between 1100 ~ 1700 ° C. Slagging property of coal refers to whether ash and slag are easy to agglomerate during coal combustion or gasification. The strength of slagging is expressed by the slagging rate, which is not conducive to combustion and gasification.

Slagging property is related to ash content, ash softening temperature, sulfur content and carbonate content. Those with heavy ash, low melting point and high content of sulfur and carbonate are easy to slag. The influence of slagging and ash softening temperature should be comprehensively considered when selecting fuel from the combustion point of view.

Dispersion and stacking angle of coal
Fluidity refers to the relative mobility between solid fuel particles and blocks under the action of gravity, which mainly depends on the friction and adhesion between particles. The coal with large fluidity is not easy to accumulate, and will flow around like a fluid, with a small accumulation angle; Coal with small fluidity is easy to accumulate and has a large stacking angle. When the stacking angle of the coal pile is equal to or greater than 90 °, it can be considered that the fluidity is lost. Therefore, the stacking angle reflects the size of the dispersion to a certain extent. The increase of mechanical moisture adsorbed by coal will worsen the fluidity, which will disappear when the limit moisture is reached.