Kinetics of Gaseous Species Formation During Steam Gasification of Municipal Solid Waste in a Fixed Bed Reactor

Abstract

Surrogate municipal solid waste (MSW) has been prepared to represent high plastic content waste with low fixed carbon in order to be utilized for feedstock for the gasification and pyrolysis. The major components are plastic (PE and PP), food and kitchen waste, and paper, whereas the minor components are textile, rubber, and biomass. Reactions were conducted in small drop tube fixed bed reactor with isothermal reaction temperature at 700, 800, and 900 °C. Steam was supplied as the gasifying agent for the main purpose of producing hydrogen-rich gas. Pyrolysis was also conducted at the same condition to observe the characteristic differences. Producer gas, including H2, CH4, and CO, of both the reactions was a function of the temperature, whereas CO2 showed a reversed trend when the reaction temperature was increased. Simple kinetic models of those gaseous formations were studied for describing the related parameters. It is challenging to determine the kinetics of the individual gas generation while most kinetic studies have focused on mass deterioration. The commonly used kinetic model of nucleation of Avrami–Erofe'ev (A2) could well predict the mechanism of the gas formation of gasification. In parallel, the pyrolysis conformed to the A3 model due to the slower rate of char and tar decomposition when the gasifying agent was absent. The activation energy of each gaseous species and the fitting of experimental data with the selected models are examined in this study.