Simplified method for the tensile strength estimation of coal particles

Significance 

Fossil fuels have been used to energize the globe for centuries. Even with the increasing strict carbon emission regulations imposed to mitigate the emission of greenhouse gases and global warming, eliminating the use of fossil fuels is out of consideration due to underdeveloped alternative renewable energy sources capable of meeting the current world energy demands. In particular, fragmentation of coal particle has attracted significant attention of researchers for the realization of effective utilization of coal.

Unfortunately, particle fragmentation mechanisms, as well as the effects of the mechanical properties of coal, have not been fully explored. Interestingly, recent studies have elucidated that tensile failure is among the key factors influencing the fragmentation of coal particles. To this end, several methods such as conventional and bending tests have been developed to determine the tensile strength of coal particles. However, most of these methods involve the determination of the tensile strength of regularly shaped particle samples.

Alternatively, studies have shown that tensile strength significantly influences the various coal conversion processes as well as their physical and mechanical properties. Therefore, a proper understanding of the tensile properties of irregularly shaped coal particles have been identified as a promising solution for determining the fragmentation behavior of particles. Furthermore, this should also be extended to determine the effects of the fuel properties as well.

To this note, Dr. Shan Zhong at Sichuan University together with Felix Baitalow, Markus Reinmöller, and Dr. Bernd Meyer at the Institute of Energy Process Engineering and Chemical Engineering in Germany assessed the relationship between the fuel properties and the tensile strength of irregularly shaped coal particles. The main aim was to understand the stress-induced coal fragmentation during various coal application processes. The work is published in the research journal, Fuel.

Briefly, the experiment entailed using eleven different types of coal with particle sizes ranging from 0.8-6.3 mm. Next, the influences of different fuel properties on the magnitude of the tensile strength of coal particles were investigated. Furthermore, a simplified prediction model was developed to predict the tensile strength of the particles.

The authors observed that the tensile strength was majorly influenced by the particle sizes: an increase in the particle size led to a corresponding decrease in the tensile strength. Coal particles with medium carbon content exhibited higher tensile strength as compared to those with low and high carbon content. On the other hand, other factors like ash content and porosity also showed considerable effects on the tensile strength with the decrease in the porosity and increase in the ash content leading to an increase in the tensile strength.

In summary, the authors investigated the various factors affecting the tensile strength of irregularly shaped coal particles. Apart from the effects of the particle size, the effects of the fuel parameters were narrowed down to only two i.e. ash and carbon contents considering the fact that they are significantly related with the other influencing factors , making the tensile strength of coal particles directly available from the proximate and ultimate analysis of coals. Therefore, the study will advance the investigation of the tensile strength of coal particles for a better description of various coal utilization and conversion processes.

Simplified method for the tensile strength estimation of coal particles - Advances in Engineering

About the author

Dr. Shan Zhong has received his doctoral degree of Process Engineering in the Institute of Energy Process Engineering and Chemical Engineering (IEC) at Technische Universität Bergakademie Freiberg, Germany in 2017. Since 2018 is he an Assistant Professor in the School of Chemical Engineering, Sichuan University, Chengdu, China. His research interests focus on coal gasification, coal particle fragmentation, CO2 utilization etc.

About the author

Dr. Markus Reinmöller has received his doctoral degree in physics. Since 2012 he is research associate in the field of mineral matter of coals and biomasses in various conversion processes. Since 2016 he is senior scientist and lecturer candidate at the Institute of Energy Process Engineering and Chemical Engineering (IEC) at Technische Universität Bergakademie Freiberg, Germany.

Reference

Zhong, S., Baitalow, F., Reinmöller, M., & Meyer, B. (2019). Relationship between the tensile strength of irregularly shaped coal particles and various fuel properties. Fuel, 236, 92-99.

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