Microwave pyrolysis of scrap tires and its pyrolysis oil performance in diesel engine

Abstract

Microwave assisted pyrolysis of scrap tires allows recovery of energy and useful materials, such as pyrolytic oil, char and gases. Scrap tire were being heated in inert atmosphere at temperature between 400 and 600 °C to produce liquid fuel. In this study, a modified conventional microwave and equipped with a custom made quartz reactor was used in pyrolysis process of scrap tire. Microwave pyrolysis process were performed with and without activated carbon as microwave absorbent. The effect of heating temperature and activated carbon on pyrolysis yield were studied. Pyrolytic oil was characterized for calorific value, composition and compound functional group. Temperature of 500 °C was the optimum temperature for the highest yield of pyrolytic oil at 54.39 wt% was obtained at the run of experiment with activate carbon as microwave absorbent. The obtained tire pyrolytic oil possessed high calorific value in range of 42.09 – 43.07 MJ/kg. The benefit of this thermal treatment was conversion of waste material into high calorific pyrolytic oil, which could be burnt directly in an unmodified diesel engine. Moreover, tire pyrolytic oil was blended with petroleum diesel and biodiesel at different ratio for performance and exhaust emission study. Engine performance such as engine torque, engine brake power, brake specific fuel consumption and brake thermal efficiency were examined with different blend ratio of fuel. Results showed neat pyrolytic oil showed an average of 7.93% lower torque and emission of carbon monoxide (CO), hydrocarbon (HC), nitrogen oxides (NOx) and sulphur dioxide (SO2), at an average of 207.4 %, 201.7 %, 42.5 % and 580.7 % higher, respectively than that of petroleum diesel fuel. At an optimum temperature of 500 °C the consumed electrical energy required to produce per unit mass of tire pyrolytic oil was 2.698 kWh/kg.