Investigation on the spontaneous combustion of refuse-derived fuels during storage using a chemiluminescence technique

Abstract

Refuse-derived fuel (RDF), a high-caloric material, is used by various combustion processes, such as power plants, as alternative fuel. Several explosion accidents, however, possibly initiated by the spontaneous combustion of stored RDF, have been reported in Japan. Therefore the spontaneous combustion of RDF prepared from domestic garbage was investigated using chemiluminescence. RDF samples were heated either under air or under nitrogen for 1, 2, or 4 h at 120 or 140 degrees C and then cooled by an air or nitrogen stream. All RDF samples exhibited chemiluminescence. In air-treated RDF samples (heated and cooled by air), chemiluminescence after ageing was shown to be slightly lower than before ageing, whereas in nitrogen-treated samples (both heated and cooled by nitrogen) chemiluminescence decreased significantly after ageing. When nitrogen was replaced with air during aging, however, a sudden increase of chemiluminescence was observed. On the other hand, when cooling was done with air, chemiluminescence increased. Higher chemiluminescence was also observed during high-temperature treatment. Further experiments on cellulose, one of the major components of domestic garbage, exhibited similar chemiluminescence patterns to those of RDF when treated by the same methods as those used for RDF ageing. Chemiluminescence from cellulose increased significantly when the atmospheric gas was changed from nitrogen to air, suggesting that oxygen in the air promoted the formation of hydroperoxide from cellulose. Therefore, it is hypothesized that cellulose plays an important role in the formation of chemiluminescence from RDF. The formation of chemiluminescence indicated that radicals are formed from RDF by oxidation or thermal degradation at room or atmospheric temperatures and may subsequently lead to spontaneous combustion.

Heat accumulations and fire accidents of waste piles

“…In the case of RDF, it is thought that most important factor of the primary heat generation is water related phenomena such as water absorption or fermentation (Fu et al, 2005;Matsunaga et al, 2005; Special Committee for Investigation on the Accident of Refuse Derived Fuel Power Plant in Mie Prefecture Japan, 2003). The reaction heat value of RDF with water was evaluated by using MMC-5112-I.…”

“…Suzuki (2004) reported those elementary atomic compositions were C (50 wt%), H (7 wt%), O (30 wt%), N (1 wt%), S (0.5 wt%), and Cl (0.5 wt%). Table 1 shows the main compositions of RDF (Matsunaga, Yasuhara, Yamamoto, Shimizu, & Wakakura, 2005). Many of them were compressed into pellets (f 10-20 mm  30-50 mm), with less than 10 wt% of water and about 2 wt% of calcium hydroxide for maintaining its hardness.…”

Investigation of the self-heating and spontaneous ignition of refuse-derived fuel (RDF) during storage

“…It is hypothesized that when RDF is exposed to air, oxygen is absorbed. The absorbed oxygen is changed to reactive peroxide by various actions, such as heat, light, and microorganisms, and consequently these accumulated peroxides cause the spontaneous ignition (Matsunaga et al, 2008). The research group of J-Power Co. Ltd. (Tokyo, Japan) estimated the possible physical processes of temperature elevation from the chemical oxidation stage to the occurrence of ignition by a computer modeling system using data from various storage conditions of RDF, including specific heat, particle density and filling bulk density of RDF as well as packed bed voidage, air viscosity, thermal conductivity of an apparatus, and heat production from a belt comber (Akasaka et al, 2008).…”

Evaluation of Various Solid Biomass Fuels Using Thermal Analysis and Gas Emission Tests

“…Huge amounts of RDF were stored in a silo and other storage facilities, where it sometimes generated heat and initiated fires. One explosion occurred during fire-fighting against heat generation in a RDF silo, and two firemen were killed in August 2003 by an explosion shown in Figure 2 [6,9]. The explosion occurred because methane was produced by anaerobic organisms.…”

“…These potential fuels include RDF (= refuse derived fuel), RPF (= refuse paper & plastic fuel), wood chips, coal-wood mixtures, chicken dung, etc. However all these fuels have high energy potentials and may cause fires and explosions [3][4][5][6]. We have experienced many incidents with these materials in Japan.…”