Abstract
The gases evolution during the low-temperature oxidation of coal is an essential parameter used to assess the state of coal oxidation and to estimate the gaseous pollutants. However, the current semi-quantitative method, which employs gas concentration as the measurement standard, is flawed. This paper presents a quantitative calculation method for gas products during coal oxidation. N2 is used as the tracer gas in the experiment, because nitrogen is an inert gas that will not participate in the reaction, and the amount of matter will not change in the reaction. According to the formula \({\textrm{M}}_i=\frac{X_i}{X_{N_2}}\times {V}_{N_2}\times {\rho}_i\), the corresponding mass flow rates of each gases component were calculated, and the gas yields during the reaction period were determined by comprehensive calculation. To this end, experiments were conducted on the low-temperature oxidation of coal using a flow reactor. After undergoing quantitative calculations, the main gas products’ mass flow rates, yields, and energies, including CO, CO2, CH4, C2H4, C2H6, C2H2, and C3H8 between 30 and 180 °C were obtained. The findings showed that CO2 > CO > CH was generated in all the coal samples. The amount of gases produced in the low-temperature oxidation of coal is proportional to the level of oxygen concentration. When the oxygen concentration ranges from 0 to 21%, the gaseous production of MTH coal ranges from 381.44 g/ton to 8562.80 g/ton. The results of gaseous energy calculations showed that the energy loss for low temperature oxidation of the four coal samples ranged from 4334.14~26,772.73 kJ/ton under air atmosphere. Energy loss is also significantly affected by the oxygen concentration, and the energy loss of MTH coal increases significantly from 520.52 kJ/ton at 0% oxygen concentration to 26,772.73 kJ/ton at 21% oxygen concentration, an increase of about 50 times. Significantly, this method not only reflects the real gas evolution during low-temperature oxidation of coal but also computes the gas emission and energy loss, which is crucial for studying the mechanism of coal spontaneous combustion and assessing gases pollutants.
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Abbreviations
- MTH:
-
Mataihao
- XJ:
-
Xinji I
- ZJ:
-
Zhangjixi
- GH:
-
Gaohe
- M i :
-
Mass flow rate
- X i :
-
Molar fraction
- ρ i :
-
Respective gas density at standard temperature and pressure
- \({X}_{N_2}\) :
-
Molar fraction of N2
- \({V}_{N_2}\) :
-
Volume flow rate of N2
- Yi :
-
Yield of each gas
- t :
-
The reaction time
- T :
-
Reaction temperature
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Funding
This work was supported by the “Outstanding Youth Research Project of Anhui Province (2022AH030084)”, and the “National Natural Science Foundation of China (No.52104178)”, and their supports are gratefully acknowledged.
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All authors contributed to the study conception and design. Jinhu Li: investigation, visualization, writing—original draft, getting funding; Qin Cao: investigation, visualization, writing—original draft; Wei Lu: methodology, project administration, writing—review and editing; Jingjuan Geng: investigation, review & writing; Jinliang Li: investigation, visualization, writing—original draft; Hui Zhuo: investigation, review & writing.
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Li, ., Cao, Q., Lu, W. et al. Quantitative calculation of gases generation during low-temperature oxidation of coal. Environ Sci Pollut Res 30, 113774–113789 (2023). https://doi.org/10.1007/s11356-023-30219-y
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DOI: https://doi.org/10.1007/s11356-023-30219-y