The production of hydrogen-rich gas by catalytic pyrolysis of biomass using waste heat from blast-furnace slag

Abstract

The granulation for molten slag produces a large amount of sensible and recoverable heat. In this paper, a system was proposed to simultaneously produce glassy slag and reuse the heat for production of hydrogen-rich gas via biomass catalytic pyrolysis. A variety of parameters, including slag temperature, mass ratio of slag to biomass (S/B), particles size, and rotor speed, were evaluated for their effects on pyrolysis product yields and gas characteristics. The catalytic activity of blast-furnace (BF) slag for improving tar cracking was also addressed. The conditions of 1000 °C of slag temperature and 0.6 of S/B achieved a complete pyrolysis of biomass. When the S/B value increased to 0.8, a lower slag temperature (700 °C) can afford a complete pyrolysis of biomass. The maximum gas yield was gained at a rotor speed of 16 rpm/min, when slag particles in reactor showed a “cascading” movement. BF slag exhibited a catalytic activity in tar cracking and CnHm reforming during biomass pyrolysis process. Furthermore, decreasing the slag particle size favored to produce more light gases, and less char and condensate. However, the effect of slag particle size became not evident in the subsequent catalytic reforming process.