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 be softened and melted into liquid when heated. Different ash content has different softening temperatures and melting points. Ash with low softening temperature and melting point may be viscous or molten in the combustion chamber, thus hindering air circulation and affecting normal combustion or vaporization.
Generally, the temperature at which the ash begins to soften is called the deformation temperature, the temperature at which the ash is completely softened is called the softening temperature, and the temperature at which the ash melts as a fluid is called the melting temperature. The softening temperature has a definite relationship with the melting point. According to the ash softening temperature, ash can be divided into four types: fusible (melting point less than 1100 ° C), low melting (the melting point between 1100 ° C and 1250 ° C), high melting (the melting point between 1250 ° C and 1500 ° C) and refractory (melting point greater than 1500C). The ash-softening temperature of coal in China is 1100~1700 ° C. The slagging property of coal refers to whether the ash is easy to agglomerate during coal combustion or gasification. The degree of slagging is expressed by the slagging rate, which is not conducive to combustion and gasification.
The slagging property is related to ash content, ash softening temperature, sulfur content, and carbonate content. Those with heavy ash content, low melting point, and high sulfur and carbonate content are easy to slag. The influence of slagging property and ash softening temperature should be comprehensively considered when selecting fuel from the perspective of combustion.
Fluidity 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 high mobility is not easy to accumulate, but will flow around like a fluid, with a small accumulation angle; The coal with small mobility is easy to accumulate, and the accumulation angle is large. 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 mobility to a certain extent. The increase of mechanical moisture absorbed by coal will worsen the fluidity, and the fluidity will disappear when the limited moisture is reached.