Study On Combustion Kinetic Characteristic Of Oil Droplets Produced By Pyrolyzing Waste Tire Rubber

The proportion of oil products in waste tire pyrolysis is as high as 50%,and resource utilization of waste tire pyrolysis oil（TPO）becomes an essential part in the disposal process of waste tires.However,the combustion characteristic parameters of waste tire pyrolysis oil are insufficiently studied due to its complex composition,which limits the use of TPO as a clean fuel.Therefore,it is urgent to study the basic characteristic parameters of TPO combustion process for the design of industrial combustion system.The main content of this thesis is the combustion kinetic characteristic parameters of TPO from typical household vehicle and freight truck tires.Semi-steel radial tires for vehicles and full-steel radial tires for trucks were utilized as raw materials,which were pyrolyzed in a three-stage micro-negative-pressure screw reactor.Firstly,2 TPO samples（NRTO:semi-steel tire pyrolysis oil;SRTO:full-steel tire pyrolysis oil）were obtained by using a circulating oil cooling system with a condensation temperature of 25°C,and their physical parameters were tested.At the same time,GC-MS and TG-FTIR were utilized to analyze their components and combustion kinetic parameters.It was found that the flash point of TPO at 25°C condensation temperature was lower than 30°C,therefore,the temperature of the oil cooling system was raised to a maximum of 130°C,and 2 new TPO samples were produced.Their flash point was 10-20°C higher than that of 25°C condensed samples,and their composition distribution was tested by GC-MS again.Finally,the combustion flame shapes,combustion rates,heat and mass transfer parameters and flame stand-off ratio（FSR）of 4 condensed oils were investigated using a single particle combustion device.Combined with droplet combustion model,the maximum mass loss rates of the 4 TPO droplets in stable combustion stage were further calculated.The research results show that nitrogen content of SRTO is higher than that of NTRO.Besides,SRTO contains more high-carbon substances（C>10）.In terms of composition,NTRO possesses two more components:ethylbenzene and styrene.Weight loss of TPO combustion is mainly divided into two stages,while the corresponding Eαare 30-40 k J/mol and 10-20 k J/mol,respectively.At the beginning of combustion,separation of C-containing groups and carbonization reactions occur first.Incomplete combustion lead to the production of CO,N and S are finally discharged in the form of NO and SO₂respectively.At the condensation temperature of 25°C,SRTO made from synthetic rubber exhibits a higher stable burning rate（1.93±0.03 mm²/s）than NTRO from natural rubber.Compared with gasoline（6）₇-2))≈0.14W/（m·K）,B>10,FSR>5),diesel（0.12 W/（m·K））and methanol（0.21 W/（m·K））,The 4 TPO droplets in this work has a larger local heat transfer coefficient（6）₇-2))>0.3 W/（m·K）),while its mass transfer number（B≈2.5）and FSR（<3.1）are much smaller,and their maximum mass loss rates in stable combustion stage are 3-5 g/s.The above could be used to guide the industrial atomized combustion and the design of subsequent specific burners,and could help to optimize the combustion conditions of TPO.