Pyrolysis, Combustion, and Steam Gasification of Various Types of Scrap Tires for Energy Recovery

The energy recovery from carbonaceous materials is considered a reliable energy source. In this context, pyrolysis, combustion, and gasification characteristics of scrap truck and car tire samples were investigated using a thermogravimetric analyzer coupled with mass spectrometer system. Pyrolysis behavior of the sample was estimated in argon atmosphere with the heating rate of 40 K/min over the temperature range of 100–1100 °C. The combustion and gasification studies of the tire samples were conducted in oxygen and steam ambiences, respectively. In addition, the size effect of the truck tire has been examined. The ignition temperature, temperature of maximum mass loss rate, and burn-out temperatures of both truck and car tires were measured. The pyrolysis gas mainly consisted of hydrogen, hydrocarbons, and carbon oxides, whereas in the condensable gases (pyrolytic liquids) mainly aromatic hydrocarbons and alcohols were detected in the temperature range of 300–500 °C. In the combustion processes, mostly CO and CO₂ gases were released; besides some hydrocarbons were also evolved. Moreover, the release of sulfur compounds and nitrogen oxides were detected in pyrolysis and combustion stages, but the nitrogen oxide was predominant in the later stage. The complete gasification conversion of scrap tire is taking place at 950 °C during the isothermal condition in steam ambience. The main products detected during gasification were CO₂, CO, and H₂, indicating that oxidation, water gas, and water gas shift reactions were predominant. The emission of sulfur compounds during combustion and gasification reactions implied the presence of sulfur in pyrolyzed char. The results indicated that the scrap tires can be used as a potential energy resource. The activation energy (Eₐ) was calculated from the thermogravimetric test results by using an Arrhenius-type kinetic model.