Gasification of Shenhua Bituminous Coal with CO2: Effect of Coal Particle Size on Kinetic Behavior and Ash Fusibility

Jinzhi Zhang,Ruidong Zhao,Jinhu Wu,Zhiqi Wang

doi:10.3390/en13133313

Abstract

Coal gasification is the process that produces valuable gaseous mixtures consisting primarily of H2 and CO, which can be used to produce liquid fuel and various kinds of chemicals. The literature shows that the effect of particle size on coal gasification and fusibility of coal ash is not clear. In this study, the gasification kinetics and ash fusibility of three coal samples with different particle size ranges were investigated. Thermogravimetric results of coal under a CO2 atmosphere showed that the whole weight loss process consisted of three stages: the loss of moisture, the release of volatile matter, and char gasification with CO2. Coal is a heterogeneous material containing impurities. Different grinding fineness leads to different liberation degrees for impurities. As for the effect of particle size on TG (thermogravimetry) curves, we found that the final solid residue amount was the largest for the coal sample with the smallest particle size. The Miura-Maki isoconversional model was proved to be appropriate to estimate the activation energy and its value experienced a slow increase when the particle size of raw coal increased. Further, we found that particle size had an important impact on ash fusion temperatures and small particle size resulted in higher ash fusion temperatures.

Highlights

Coal, as a traditional fossil fuel, will continue to be dominant in China’s energy sector for a relatively long time [1]
The effect of particle size on TG curves was reflected in the final amount of solid residue when the temperature was higher than 1050 ◦ C
The coal sample with the smallest particle size had the largest final solid residue amount, which was consistent with the results of the ash amount in the proximate analysis

Summary

Introduction

As a traditional fossil fuel, will continue to be dominant in China’s energy sector for a relatively long time [1]. Coal gasification technology deserves attention because it is the process that produces valuable gaseous mixtures consisting primarily of H2 and CO (syngas) with high fuel conversion efficiency [2]. Char gasification is usually a slower process than pyrolysis and is the rate-limiting step of the whole process; the knowledge of gasification kinetics is vital for designing gasification reactors [2]. The most frequently utilized gasification agents include O2 , air, H2 O, and CO2 , among which steam is the most widely used [2]. Unlike CO2 , water is resource-limited and energy-intensive. CO2 is less reactive than steam, it is still widely used in the coal gasification process because it can reduce the dependence on water resources [5]

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Discussion

Conclusion