Study On Moisture Generationg Mechanism Of Lignite In Low Temperature Oxidation

Moisture generating mechanism of lignite in low temperature oxidation is the key and difficult research on low-temperature oxidation mechanism.The spontaneous combustion of Indonesia lignite is taken as this paper research object,the two species H₂O generation monitoring plan which include hanging type and sat vertical type water generation monitoring plan has been designed,the advantages and disadvantages of two species plan are analyzed and compared,and the H₂O generation monitoring experiment eventually is built from the sat vertical type.The coal is oxidized in air and heated in nitrogen,respectively,to investigate the production of H₂O during oxidation;the effects of oxygen concentration,moisture content in coal and mass of coal are also investigated.The fast low temperature oxidation experiment is monitored in completely dry of coal sample,the coal bed temperature and oxidation gas product H₂O concentration,combining separation point temperature?SPT?and crossing point temperature?CPT?with oxidized gaseous products?H2O?features,the kinetic model of H₂O in low temperature oxidation is established,and the H₂O activation energy of different oxygen concentrations and gas flow,different size,different ways of drying of lignite is obtained during low-temperature oxidation.Experimental data indicate that production of H₂O is higher at higher oxidation temperature.The production of H₂O in gas flow progressively increase with increasing oxygen concentration,because the increase of partial pressure of oxygen promote the physical and chemical adsorption of O2 on coal surface.The production of H₂O progressively increase with increasing moisture content in coal.Although temperatures of coal with more mass slowly increase with increasing oven temperature,due to higher thermal capacity,the coal release more heat during oxidation,generating more H 2O.The process of low temperature oxidation has a corresponding stage law,it would be divided into three oxidation stages with characteristic temperature?SPT,and CPT?regarded as the transition point temperature;accessing to finding the kinetic parameters math of H₂O during low temperature oxidation:ln The activation energy of H₂O is obtained by fitting each stage in the process of gas production,with this dynamic model gaining the different oxygen concentrations and gas flow,different size,different ways of drying during low temperature oxidation.