THE STUDY OF ANAEROBIC CHAR RELATED TO FIRE

Abstract

“Pyrophoric Carbon” often associated with the capability of self heating which lead to the occurrence of self-ignition or spontaneous combustion. Its existence however, is still a myth which has evoked disputes among researchers. Therefore, many studies and experiments have been conducted to contemplate the theory of pyrophoric carbon. However, among all the experiments executed, none have attempted to study characteristics of anaerobic char which created similar to environment of actual fire; where woods being heated close to heating source. Thus, this research was initiated. This research was executed to study the characteristic of anaerobic chars. In an anaerobic condition, the woods specimens were heated at close contact with the heating source to imitate the environment of actual fire. The creation concept of the anaerobic chars was based on own original idea. Kapur and Nyatoh wood samples were used in this research. To create chars under anaerobic condition, the wood samples were first heated at 150°C for 30 days at duration of 12 hours per day. To create a heating medium under anaerobic condition, an experiment set-up was custom designed and created from own original idea to fit the purpose. After heated under anaerobic char for 30 days at the temperature of 150°C, Kapur sample had lost more weight than Nyatoh sample, with the percentage of 37.08% and 35.21% respectively. The charred wood samples were then reduced to powder form to be experimented in Thermo Gravimetric Analysis (TGA) and yet again were heated in both air and nitrogen at temperature range of 74°C to 168°C to determine oxygen chemisorption level of the char. When Nyatoh and Kapur samples were heated in air, weight loss was more prominent with percentage up to 8.61% and 5.54% respectively. However, chemisorption had also occurred although the percentage of weight gain was small. From the lowest decreasing point, weight increased up to 1.28% when the Nyatoh sample was heated at 74°C. At 109°C and 139°C, both Nyatoh and Kapur samples experienced increment in weight up to 0.70% and 0.15% as well as 0.08% and 0.5% respectively. Weight gain was more dominant in all samples when preheated in nitrogen at temperature of 74°C, 109°C and 139°C. Thus, the occurrence of chemisorption was more apparent when samples were preheated in nitrogen. The TGA results were compared to results from previous study. Char samples of this research (anaerobic char) had more significant increase in weight in most cases. The anaerobic char gained up to 0.15% when heated at 139°C, up to 0.70% when heated at 109°C and up to 1.28% when heated at 74°C while sample of previous study gained up to 0.06% when heated at 139°C with only small and no significant increase of weight when heated at 109°C and 74°C. Thus, chemisorption in anaerobic char was more apparent. Based on the findings of this research, it can be concluded that wood charred under anaerobic condition with limited amount of air or oxygen was more reactive and have pyrophoric characteristics. This might contribute in the possibility of spontaneous ignition.