Abstract:Although stored at near room temperature, a large amount of stored industrial food waste or their recycled material gradually heats up and then ignites. To understand this phenomenon, soy sauce squeezing residue produced from the soy sauce brewing process and fish meal residue from processing fish were examined. We used a thermo gravimetric/differential thermal analysis system, a highly sensitive heat flux calorimeter (C80) and a spontaneous ignition tester to study their thermal properties. We applied Frank–K… Show more
“…For both geometric shapes of cylinder and box, the curves exhibit vertical (va) and horizontal asymptotes (ha) around the coordinates y va = 8 km; x va = 60 °C and y ha = 6 km; x ha = 60 °C when the selected dimensions were increased or decreased to near infinity while keeping the respective ratios. The findings confirm the report of Murasawa et al ( 2013 ) on storage of soy sauce residue and fishmeal, in which similar asymptotic responses were detected. Fig.…”
This study investigated the combustion kinetics and spontaneous ignition of sweet sorghum using thermogravimetric analysis and the Frank-Kamenetskii theory. The aim was to determine the proper operating conditions for a direct combustion reactor and predict the safe ambient temperature limits for given silo designs. Oxidative heating rates of 2, 5, and 10 °C/min were set up. Graphical observation shows that combustion was composed of two different stages representing the overlapping processes of pyrolysis and char oxidation, at 131–336 °C and 336–475 °C, respectively. Samples were found to ignite at 215 °C and were extinguished at 433 °C. Different heating rates shifted combustion characteristics to higher temperatures and increased reactivity for ignition and combustion indices up to 12 and 10 times higher. The Friedman method determined the apparent activation energies representing the combustion reaction by 132.91 kJ/mol. Regarding spontaneous ignition, the temperature safe limits were predicted to be 83–84 °C and 84–87 °C for cylindrical and box silos with diameter and height of 15 and 10 m, respectively. Calculations of silos were designed within the limits of certain dimension ratios.
Graphical Abstract
“…For both geometric shapes of cylinder and box, the curves exhibit vertical (va) and horizontal asymptotes (ha) around the coordinates y va = 8 km; x va = 60 °C and y ha = 6 km; x ha = 60 °C when the selected dimensions were increased or decreased to near infinity while keeping the respective ratios. The findings confirm the report of Murasawa et al ( 2013 ) on storage of soy sauce residue and fishmeal, in which similar asymptotic responses were detected. Fig.…”
This study investigated the combustion kinetics and spontaneous ignition of sweet sorghum using thermogravimetric analysis and the Frank-Kamenetskii theory. The aim was to determine the proper operating conditions for a direct combustion reactor and predict the safe ambient temperature limits for given silo designs. Oxidative heating rates of 2, 5, and 10 °C/min were set up. Graphical observation shows that combustion was composed of two different stages representing the overlapping processes of pyrolysis and char oxidation, at 131–336 °C and 336–475 °C, respectively. Samples were found to ignite at 215 °C and were extinguished at 433 °C. Different heating rates shifted combustion characteristics to higher temperatures and increased reactivity for ignition and combustion indices up to 12 and 10 times higher. The Friedman method determined the apparent activation energies representing the combustion reaction by 132.91 kJ/mol. Regarding spontaneous ignition, the temperature safe limits were predicted to be 83–84 °C and 84–87 °C for cylindrical and box silos with diameter and height of 15 and 10 m, respectively. Calculations of silos were designed within the limits of certain dimension ratios.
Graphical Abstract
“…Heat generation was considered for two periods: 0-24 h, and 24-72 h. In addition, heat generation was considered for a combination of both time periods. The TAM-III temperature was held at 50 • C for all tests, because microbial activity occurs most vigorously in this temperature range but disappears at higher temperatures [16,17].…”
In the Japanese agricultural industry, efforts are being made to recycle waste produced in order to use resources more efficiently. However, in some cases, when stored for long periods of time these materials generate heat through fermentation, which can eventually result in spontaneous ignition or oxygen deficiency in storage areas, resulting in the deaths of workers. In this study, we conducted a series of experiments on several types of agricultural waste (organic waste generated by agricultural production activities in Japan) frequently stored for recycling, using combinations of various thermal-and gas-analysers, in order to identify the risk factors related to spontaneous ignition and oxygen deficiency accidents. The aim of this research was to understand the circumstances leading to spontaneous ignition and oxygen deficiency accidents in storage facilities and to recommend safety measures to prevent such occurrences. Our results suggest that fermentation is likely responsible for the generation of heat and production of carbon dioxide at temperatures up to approximately 50 • C, where microbial activity diminishes. At temperatures beyond 50 • C, a transition into heat generation by the oxidation of fatty acid esters occurs. Additionally, when the barrier of heat absorption is overcome at around 100 • C due to the evaporation of water, there is a transition to thermal cracking that could lead to fire. Accidents due to oxygen deficiency may occur when a storage facility is well sealed and the amount of oxygen circulation is minimal. However, when the amount of oxygen is sufficient; the substance is stored in large deposits; and the facility is well insulated, fermentation can cause the temperature to increase. Therefore, it is desirable to periodically measure the temperature of stored materials and monitor the generated gases.
“…Heat generation has been considered for two periods: 0-24 h, and 24-72 h. In addition, heat generation was considered for a combination of both time periods. The TAM-III temperature was held at 50 °C for all tests, because microbial activity occurs most vigorously in this temperature range but becomes inactive at higher temperatures [16,17]. Considering the thermal behaviour of wood pellets (made from tree bark), once distilled water is added, heat generation begins immediately and increases again after 24 h. This is assumed to occur because microorganism activity increases over a period of time.…”
New biomass fuels are constantly being developed from renewable resources in an effort to counter global warming and to create a sustainable society based on recycling. Among these, biomass fuels manufactured from waste are prone to microbial fermentation, and are likely to cause fires and explosions if safety measures, including sufficient risk assessments and long-term storage, are not considered. In this study, we conducted a series of experiments on several types of newly developed biomass fuels, using combinations of various thermal-and gas-analysers, to identify the risks related to heat-and gas-generation. Since a method for the evaluation of the relative risks of biomass fuels is not yet established in Japan, we also such a method based on our experimental results. The present study found that in cases where safety measures are not thoroughly observed, biomass fuels manufactured from waste materials have a higher possibility of combusting spontaneously at the storage site due to microbial fermentation and heat generation.
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