The production of fuel oil and combustible gas by catalytic pyrolysis of waste tire using waste heat of blast-furnace slag

Abstract

In this study, a novel “waste energy recycling” strategy is presented, i.e., the sensible heat of blast-furnace (BF) slag is utilized for the production of fuel oil and combustible gas from the pyrolysis of waste tire. The effects of various operating parameters including the slag temperature, the mass ratio of BF slag to tire (B/T) and feedstock size on yields and characteristics of pyrolysis products were systematically studied. The results showed that the presence of BF slag greatly improved the production of derived-oil and increased the contents of H2 and CO in pyrolysis gases. This can be explained by the catalytic activity of BF slag and the CaO-MgO complex in BF slag can prevent the formation of stable chemical structures in hydrocarbons, speed up the degradation of hydrocarbons, weaken CC and CH bonds and make them dissociate more easily, and thereby decrease the activation energy of degradation reactions. Increasing BF slag temperature and B/T ratio, and decreasing feedstock (including both BF slag and tire powder) size favored the heat and mass transfer during pyrolysis process and therefore afforded more liquid and gaseous products. In addition, it was observed that the presence of BF slag decreased viscosity, density, H and O content and increased C content, C/H ratio and calorific value of derived-oil relative to pyrolysis oil derived from solely tire powder, thereby resulting in upgradation of oil quality.