Study On Low-temperature Oxidation And Caking Properties Of Asphaltite

The caking action between fuel particles will aggravate when the burning temperature is too high or exceeds the initial bonding temperature of the fuel during boiler combustion,then it will melt and bond,which may be easy to cause serious slagging and ash deposition,thus the heat transfer effect is greatly reduced and the efficience of the boiler is decreased.To relieve this phenomenon,this article is mainly to modifie asphaltite by low temperature oxidation and explore the effect of improvement about asphaltite's viscosity,by testing the oxidation sample and carring out pyrolysis experiment to explore the adhesion of asphaltite.Firstly,using the fixed bed as reactor,asphaltite is the research object,the initial bond temperature is index,then studying the effect of oxidation temperature,oxidation time and particle size on the viscosity of asphaltite.The study found that low-temperature oxidation improved the caking action between asphaltite,and the best pretreatment conditions is 240degree Celsius,20 mins,and 1-1.4mm,the research also discovered that the temperature was the main factor affecting the caking action,but not only increasing the temperature can make the oxidation reaction rate increase and improve the caking,according to Design-Expert,the interaction of time and particle size on viscosity is more significant.Secondly,the oxidation characteristics and bonding mechanism of asphaltite were studied.using extraction experiment,FTIR test,thermal analysis The results showed that the CS₂-NMP mixed solvents has the highest extraction rate and good dissolving capacity.However,the extraction rate of oxidised samples were decreased,which revealed that low-temperature oxidation could cause the viscous component decreased.We can found the formation of ether bond and shorten of the aliphatic carbon chain according to FTIR,which were benefit to the decrease of viscosity.In addition,the formation of the ether bond contributes greatly to the decrease in viscosity.The thermal decomposition temperature and maximum weight loss temperature of oxidated sample were higher than raw sample,and pyrolysis endothermic peak weakened;in addition,activation energy of the oxidated sample was also increased,so pyrolysis was difficult to happen and viscosity was alleviated.Finally,the pyrolysis characteristic of asphaltite was studied.Mainly using GC test,FTIR test and SEM test,and asphaltite,addition of Kaolin,pretreated sample were experimental samples,fixed bed was also used as reactor.With the increase of pyrolysis temperature,the yield of solid product decreased and the yield of gas product increased.The addition of Kaolin promoted the decomposition of liquid product and inhibited the formation of CO.In addition,Kaolin can obstruct the contact between metaplast at a lower pyrolysis temperature,which can alleviate the melting characteristic of asphaltite.Low-temperature oxidation pretreatment reduced component of metaplast,so the melting phenomenon was alleviated.According to infrared test,it also discovered that viscosity was related with aliphatic,phenol,alcohol,ether etc.