Study On Catalytic Combustion Reaction Characteristics And Mechanism Of Beipiao Oil Shale

Due to the low grade of combustion characteristics,low calorific value,high ash content of oil shale,it is usually used as'a flame-resistant fuel in power plants.In order to better improve the utilization of oil shale and alleviate the problem of coal resource consumption,it has become a topic of increasing concern to propose an effective method to promote combustion.Therefore,in this paper,Beipiao oil shale was selected as research object,potassium-based catalyst was taken as the combustion supporting agent,and catalytic combustion technology was applied to solve the combustion problem of oil shale and explore its catalytic mechanism.The combustion reaction characteristics of Beipiao oil shale were investigated by thermogravimetric analysis.The changes of fuel combustion parameters before and after adding the eatalyst were ealculated aceording to the TG/DTG curves,and the faetors affecting the catalytic effect were discussed.The results showed that the combustion of oil shale in Beipiao can be mainly divided into three stages:the water evaporation stage,the main combustion stage and the mineral decomposition stage.The catalyst accelerated the decomposition of inorganic minerals,making the third-stage combustion peak almost negligible.The catalyst addition ratio and heating rate had a crucial influence on the oil shale combustion.With the increase of the catalyst addition ratios,the TG curve moved toward lower temperature direction,the weight loss of fuel becomes more obvious,and the qualities of the residue became smaller and smaller.Among them,the catalyst with the additive amount of 5%had the best catalytic effect,reducing the ignition temperature and burn-out temperature by 2.78%and 7.79%,respectively.The higher the heating rate,the worse the combustion performance of the sample,which indicates that the lower heating rate was more conducive to the combustion reaction.By comparison,the catalyst decreases the burn-out temperature of the sample the most at 20OC/min.The catalyst reduced the ignition temperature of the sample to the maximum when the heating rate was 10?/min.TG-FTIR technology was used to study the effect of catalysts on gas precipitation products during combustion.The solid-phase infrared spectroscopy and scanning electron microscopy were used to analyze the change of the precipitation law of solid products during the combustion process of the catalyst.Studies had shown that the main gaseous product from the combustion of oil shale was CO2.The catalyst made the characteristic peaks of the third stage of.CO2 disappeared,while the carbon dioxide emissions of the second stage increased,which indicated that the catalyst accelerated the decomposition of minerals in the oil shale,which was consistent with the results of TGA.FTIR analysis results showed that the catalyst promoted the decarbonization and cracking of oil shale,which led to the decomposition of large-molecular aromatic hydrocarbons and oxygen-containing functional groups to generate small-molecular hydrocarbons and-OH,which caused an increase in phenol and alcohol compounds and promoted the release of volatiles.Scanning electron microscopy results showed that the catalysts caused the Beipiao oil shale burned more thoroughly and a "skeleton" appeared.Many small pores appeared on the surface of the oil shale sample,and the oxygen adsorption capacity increased during the surface sample combustion,and the combustion was sufficient.The Flynn-Wall-Ozawa method and Friedman-Reich-Levi method were used to analyze the kinetics of Beipiao oil shale and mixed fuels,and explore the mechanism.The results showed that the analysis results of the two methods were almost the same.The activation energy required for the combustion reaction of the Beipiao oil shale was relatively high.The catalyst significantly reduced the activation energy required for the fuel reaction,especially in the later stage of the reaction.The reason why potassium-based catalysts could promote the combustion of Beipiao oil shale was that a series of reversible reactions between the catalyst and its derivatives occur,which accelerated the oxygen transfer and made the oxygen sufficient during the combustion process and the combustion was sufficient.