• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.34-40
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• 2003

Analyses for concentration, surface phenomena, and crystal structure were performed to identify the causes of clinker formation in three type of pulverized coal fired boilers. Some clinkers had partially molten surface and more CaO and $Fe_2O_3$ as compared with fly ash, and the major crystalline phases identified in the clinker were mullite and quartz. Clinkers were formed in high temperature zone of the boiler according to the identification of mullite by XRD. Free $SiO_2$ in sand combined with K, Na and Ca in limestone served as a fluxing agent to form clinkers in a circulating bed boiler.

• Applied Chemistry for Engineering
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• v.17 no.5
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• pp.547-551
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• 2006

In the reactor following the American standard test method (ASTM) D5757-95 and lab-scale fluidized bed combustor, the attrition characteristics of sand and ash of Korean anthracite were investigated. The attrition characteristics, such as particle size distribution of fly ash, attrition rate, and attrition ratio etc, were studied with variation of gas velocities. The particle attrition of ash was more active than sand which was generally used as a fluidized material and also the attrition index of ash taken by ASTM D5757-95 was 5 times higher than that of sand. The formation of fine particles continuously occurred due to particle attrition with increasing gas velocities. The following equation has been suggested for attrition rate of ash. $$\frac{dW}{dt}=-3.18{\times}10^{-7}(U-U_{mf})W$$.

• Clean Technology
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• v.8 no.1
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• pp.1-9
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• 2002

Mild pyrolysis of four different coals (two bituminous coals and two Korean antracite) was investigated. Desulfurization characteristics, weight loss and variation of heating values were studied. As operating variables of experiment, pyrolysis temperature($350{\sim}550^{\circ}C$), pyrolysis time(5~20 min.) and particle size(0~3.55mm) were examined. The maximum sulfur removal rate of bituminous coal and anthracite were 38% and 28%, respectively. The optimum mild pyrolysis conditions were 10~15 min for pyrolysis time and $450{\sim}550^{\circ}C$ for pyrolysis temperature. The mild pyrolysis was effective to reduce organic sulfur content. Heating values of char per mass after pyrolysis increased about 5% compared to raw coal. The effect of coal particle size on the desulfurization was not observed.