Study on Fuel Oil Production from Waste Tires via Fixed-Bed Pyrolysis

Abstract

Pyrolysis of waste tires for oil production is an effective approach for resource utilization. To optimize the process parameters of fixed-bed pyrolysis of waste tires and clarify the product characteristics, this study employed a fixed-bed electric heating system to conduct pyrolysis experiments on waste tire chunks under a nitrogen atmosphere. The effects of pyrolysis time (1h and 2h) and pyrolysis temperature (270°C~620°C) on product yields were investigated, and the reliability of the experimental data was verified through repeated tests. Furthermore, the chemical composition of the pyrolytic oil was analyzed using gas chromatography-mass spectrometry (GC-MS), while the pyrolytic char was subjected to proximate analysis, calorific value measurement, and ash fusibility testing. The results showed that extending the pyrolysis time from 1h to 2h resulted in a limited increase in oil yield (less than 1%), indicating that the tires were essentially completely cracked within 1h. As the pyrolysis temperature increased, the oil yield first rose and then declined. The optimal pyrolysis temperature range was 440°C~460°C, under which the oil yield reached 35.2%~40.1% and the oil-to-gas ratio was 2.3~2.9. The average yield of solid products ranged from 44% to 53%, with an average steel wire content of 15.5%. After the temperature exceeded 320°C, the pyrolytic carbon black yield stabilized at 29%~34%. A total of 218 effective components were detected in the pyrolytic oil, among which 13 substances, including limonene (11.87%), ethanol, and phenol, each accounted for more than 1%. The pyrolytic carbon black had a fixed carbon content exceeding 80%, a calorific value of approximately 30 MJ/kg, and an ash melting point ranging from 1170°C to 1220°C. This study provides data support for the optimization of fixed-bed pyrolysis processes for waste tires and the graded utilization of pyrolysis products.