An Insight into Effects of Pore Diffusion on Kinetics of Coal Smoldering Fire Using A 4-step Chemical Reaction Model
Oxygen diffusive transport plays a crucial role in coal smoldering fires, however, its effects have been inadequately investigated.This paper aims to study influences of pore diffusions of oxygen on chemical reaction and apparent reaction rate of heterogeneous combustion of pulverized coal.To fulfill this objective, three groups of thermogravimetric (TG) tests for two bituminous coal samples at three heating rates (2, 5 and 10 K/min) are conducted, and a 4-step decomposition scheme is constructed.The decomposition schemes contain two competing paths: Coal oxidation → Char oxidation → Ash (Path One), and Pyrolysis → Char oxidation → Ash (Path Two).A number of kinetic triplets (reaction order, pre-exponential factor and activation energy) and stoichiometric coefficients of the developed decomposition schemes are optimized by Genetic Algorithm (GA).Emphasis is put on influences of each diffusion on chemical reaction (e.g.pyrolysis, coal matrixs and multiple chars oxidation) and on competing paths of heterogeneous combustion of coal.Research results show that diffusive transports barely impact pyrolysis as it takes place without oxygen, and mainly retard coal oxidation and its successive char oxidation on the Path One, but basically enhance char oxidation on the Path Two.It is the first time that effects of oxygen diffusive transport on chemical kinetics of coal combustion are revealed and the retarding influence on the apparent reaction rate of coal combustion is quantitatively estimated, which is beneficial for understanding mechanism of oxygen-transport controlled spontaneous combustion of sealed coal piles and coal-seam and peat smoldering fires.
pore diffusion kinetics non-isothermal TG Genetic Algorithm
SONG Zeyang
Jiangsu Key Laboratory of Hazardous Chemicals Safety and Control, College of Safety Science and Engineering, Nanjing Tech University, Nanjing 211816, Jiangsu, China
国际会议
The 2016 International Symposium on Safety Science and Technology(2016安全科学与技术国际会议)
昆明
英文
466-470
2016-10-17（万方平台首次上网日期，不代表论文的发表时间）