Combustion behaviour and chemical structure changes of enzyme-treated coal
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Combustion behaviour and chemical structure changes of enzyme‑treated coal Jiawei Wang1 · Zifeng Sui1,2 · Yifei Zheng1 · Tao Wang1 · Yongsheng Zhang1 · Hong Xu1 · Wei‑Ping Pan1 Received: 7 July 2019 / Accepted: 29 December 2019 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract As one of the technologies for the improvement in coal quality, biological enzyme technology has received much attention. The enzyme product named 3EC was shown to enhance the power plant performance in our previous full-scale test. In this work, its effect on coal was explored. The results indicated that the enzyme product was beneficial in the removal of organic sulphur from coal, and the catalytic action of 3EC on the cleavage of C–C and C–S bonds was proven based on data from the dibenzothiophene decomposition test. Thus, when it was used to treat coal, the CH3-to-CH2 ratio changed from 0.81 to 0.32 with an increase in treatment time, which indicated that some chemical structures in the enzyme-treated coal changed. Because of these structural changes, the combustion behaviour of coal improved, indicated by the increase in the comprehensive combustion index from 2.958 × 106 to 3.113 × 106 %2 min−2 K−3 and the decrease in activation energy from 32.76 to 30.43 kJ mol−1. In addition, the optimum enzyme treatment time should be 4 days to ensure enough reaction time between the enzyme and the coal. Keywords Enzyme · Coal · Combustion · Kinetic analysis · Chemical structure List of symbols Ti Ignition temperature Tb Burnout temperature Kmean Average mass loss rate Kmax Maximum mass loss rate S Comprehensive combustion index E Activation energy Abbreviations HRT Hydraulic retention time DBT Dibenzothiophene FTIR Fourier transform infrared spectroscopy TG Thermogravimetric analysis GC-MS Gas chromatograph coupled to an SQ 8T mass spectrometer
* Yongsheng Zhang [email protected] 1
Key Laboratory of Condition Monitoring and Control for Power Plant Equipment, Ministry of Education, North China Electric Power University, Beijing 102206, People’s Republic of China
School of Energy and Environment, Inner Mongolia University of Science and Technology, Baotou 014010, People’s Republic of China
2
Introduction In recent years, with the continuous progress in energy conservation and emission reduction, the question of how to improve the quality of coal to achieve higher combustion efficiency and lower air pollution has received increasing attention. One of the technologies used to improve the quality of coal is the use of biological enzymes, which are organic substances produced by living cells. They consist of proteins, and they have a strong catalytic effect. Enzymatic technology can be carried out under mild conditions with simple reaction equipment. It has many advantages, such as low energy consumption, low investment, safety, and environmental friendliness. Therefore, enzymes could have broad applications in the improvement in coal quality. In 1908, the catalytic effect of bacteria on the coal oxidation process was discov
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