Effects of Contact Conditions between Particles and Volatiles during Co-Pyrolysis of Brown Coal and Wheat Straw in a Thermogravimetric Analyzer and Fixed-Bed Reactor

Abstract

Biomass is a clean and renewable energy source. In order to partially replace fossil fuels and break the limitations of the usage of biomass alone, co-pyrolysis of coal and biomass has been increasingly focused on by researchers, but few articles have investigated the effects of contact conditions between volatiles produced by thermal decomposition and particles from each other during co-pyrolysis. In the present work, co-pyrolysis behavior of wheat straw (WS) and brown coal (HKN) was investigated in a thermogravimetric analyzer (TGA) up to 1100 °C and a fixed bed reactor up to 800 °C, with different contact conditions of particles (biomass was placed above, below and well-mixed with coal). The results showed that the most obvious interactions occurred for mixed sample when 10 wt.% biomass was placed below the coal and mixed sample when 50 wt.% biomass was placed above the coal, both in TGA and fixed bed reactor, with different mechanisms. The synergy effect related to interactions that occurred during co-pyrolysis lead to different behaviors compared to simply addition of coal and biomass: In TGA this was caused by longer reaction time between particles and volatile products produced in primary pyrolysis process. However, for the fixed bed reactor, much more volatiles and catalytic compounds were produced to promote the particles decomposition of WS and HKN. Therefore, opposite to TGA, obvious synergy effects occurred for the blend with less contact time and were caused by volatiles containing more H2 and catalytic materials, which reacted with particles of the other fuel species along the gas flow direction. The kinetic parameters obtained by the Coats–Redfern method agreed with experimental behaviors and synergy effects.

Characterization of Pyrolysis Products and Kinetic Analysis of Waste Jute Stick Biomass

“…Suitable models to predict the pyrolysis products are essential for the power plant optimization and to offer an improved understanding about the behavior of combustion engines fueled by pyrolysis products [12]. Thus, for a better understanding of the pyrolysis process, many researchers studied and recommended, the thermal decomposition of biomass by thermogravimetric analysis (TGA) [5,9,[13][14][15][16][17][18]. Therefore, TGA is being considered as one of the most general technique which was applied for the different kinetic analysis of devolatilization method.…”

Proxy quality control of biomass particles using thermogravimetric analysis and Gaussian process regression models

“…Thermal parameters of thermogravimetric and derivative thermogravimetric (TG/DTG) analysis can be used to predict key features of many materials, including biomass particles. It has been shown to accurately describe the pyrolysis kinetics of coconut biomass particles, 21 the char and fixed carbon yields from various wood biomass particles, 22 and the co‐pyrolysis behavior of brown coal and wheat straw biomass particles 23 . The applications of TG/DTG analysis also extends well beyond biomass particles.…”

“…It has been shown to accurately describe the pyrolysis kinetics of coconut biomass particles, 21 the char and fixed carbon yields from various wood biomass particles, 22 and the co-pyrolysis behavior of brown coal and wheat straw biomass particles. 23 The applications of TG/DTG analysis also extends well beyond biomass particles. Thermogravimetric and derivative thermogravimetric analysis has been shown to be a useful tool for determining the spontaneous ignition potential of coal, 24 identifying the presence of commercial detergent-dispersant additives used in gasoline, and even characterizing the thermal properties of functionalized polymer nanocomposites with nanoclay and Ag nanoparticles added to the polymer matrix.…”