Investigation of thermal behavior of pine sawdust and coal during co-pyrolysis and co-combustion

Abstract

Nowadays, most of the recent large-scale installations are configured to use more than one fuel. Thermal analysis allows us to properly design and operate especially such a large-scale co-pyrolysis and/or co-combustion process. In this study, thermal behaviours of pine sawdust (PS), coals, and their blends were investigated by using thermogravimetric analysis (TGA) under nitrogen and air atmospheres with different heating rates of 10, 20, and 40 °C min-1. Kinetic parameter such as activation energy (Ea) was calculated by using Kissenger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and Starink models. The results showed the existence of an obvious synergistic effect between PS and coal during pyrolysis and combustion processes. The initial, maximum, and burnout temperatures of the reactions; the mass loss rate; and total mass loss were influenced by the proportions of PS and coal in the blend. For pyrolysis the average Ea of 25PS calculated by KAS, FWO, and Starink models was found as 31.57, 40.45, and 32.55 while that of 50PS was 166.80, 168.64, and 167.25 kJ mol-1, respectively. For combustion, the average Ea of 25PS calculated by KAS, FWO, and Starink models was found as 59.57, 67.74, and 60.52 while that of 50PS was 66.60, 74.20, and 67.49 kJ mol−1, respectively. According to the Ea value, the blend of 25PS was more suitable than 50PS for energy production through both pyrolysis and combustion. This synergistic effect between PS and coal may be further detailed with more different blend ratios.