Assessment of self-heating and spontaneous combustion of Napier grass using thermogravimetric analysis

Napier grass is a potential solid biofuel that can be used as a renewable energy resource. Nevertheless, its tendency for self-heating and the subsequent self-ignition remain unknown, which are common problems in solid fuel. In this work, thermal decomposition characteristics of Napier grass in air and inert conditions were investigated using thermogravimetric analysis (TGA) and the pertinent kinetic parameters were established using model-free methods. The average activation energy of Napier grass thermal decomposition is 285 and 382 kJ/mol under oxidative and inert conditions, respectively. The linear plot obtained through model-free methods shows a high linear correlation coefficient at conversion ranges of 0.2-0.7 during combustion and 0.4-0.6 during pyrolysis. The ignition and burnout temperatures were evaluated, and ignition index of Napier grass was established. Average ignition temperature obtained for air was 217 degrees C while 200 degrees C for inert condition. The burnout temperatures between 691 and 984 degrees C were observed. This research facilitates in understanding fire threat posed by tendency of Napier grass to self-heat and provides valuable information for safe conditions of Napier grass storage and transportation.