Determination of spontaneous combustion of thermally dried sewage sludge

Pejić, Ljiljana Medić; Fernandez-Añez, Nieves; Torrent, Javier García; Ramírez-Gómez, Álvaro

doi:10.1016/j.jlp.2015.01.013

Cited by 17 publications

(11 citation statements)

References 11 publications

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“…When this method was applied to some dried sludge from wastewater, considered as a highly interesting biomass because of its energetic application, positive results were obtained, hence they are only exempt from classification if they are transported in packages smaller than 3 m 3 [19].…”

Section: Methodsmentioning

confidence: 99%

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Particle Size Influence on the Transport Classification Labels and Other Flammability Characteristics of Powders

et al. 2020

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Dust explosions and fires pose an industrial safety problem, due to the human and material losses caused by them. As many fuel processes and material transport generate powder particles, the effect of granulometry in different flammability properties has been studied to define the relationship between both. Deep knowledge of this relationship reduces the self-ignition and self-combustion processes, and the accidents associated with these processes. In this study, six different samples, including biomass, charcoal, and dog food, are tested in three different particle sizes, so differences in their flammability behavior could be appreciated (not only considering fine particles, but also coarse samples). The transport classification test was carried out, obtaining significant results in two samples, where the same material did not self-ignite when tested at its coarse size, but it did when tested at fine particle size. Similar results were obtained when analyzing initial temperature for related-combustion gasses emission: the finer the particle size, the lower the initial temperature. To understand the heat mechanisms, thermal analyses were performed, such as thermogravimetric analysis and differential scanning calorimetry. Finally, a self-ignition risk was assessed for all samples according to their activation energy and characteristic temperature. All the test results lead to conclude that biomasses easily start self-heating process, but its composition difficult the heat transmission to reach self-ignition, while charcoals are more susceptible to self-ignition.

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Section: Methodsmentioning

confidence: 99%

“…This method has been used previously to characterize the self-ignition of agricultural materials stored in silos [15,16], coals with different ranges and origin [17], biomasses [18], and thermally dried sewage sludge [19], among others. Research regarding numerical simulations has also been carried out [20,21].…”

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confidence: 99%

Particle Size Influence on the Transport Classification Labels and Other Flammability Characteristics of Powders

et al. 2020

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“…Comparing the self-ignition risk of these sewage sludge samples with other of biomass nature or even from fossil fuels [9], it is remarkable the higher dangerousness of these samples. Likewise, the location of the sludge samples in the very high and high risk areas, was already described for sludge of different origins [7].…”

Section: Thermal Susceptibilitymentioning

confidence: 99%

“…5, just SLU5 and SLU-6 are not located in the same zone, which could be attributed to the high volatiles content of both samples in comparison with the less danger sludges. In order to contrast this hypothesis, blue points correspond to sludges from the literature [7]: one of them situated in the area of maximum risk, as in Fig. 5, and the second one, located in an area of medium risk, hence the dotted line indicates that the zone of high risk comprises from 1 to 2.5 % of sulphur.…”

Section: Thermal Susceptibilitymentioning

confidence: 99%

“…In a pioneering work, Fernandez-Anez and coworkers [6] determined the explosion severity, flammability and thermal susceptibility analysis of several dried sewage sludge samples, and correlated these features and the chemical composition. Likewise, these authors evaluated the thermal susceptibility of sludge by activation energy and the characteristic oxidation temperature, observing a higher self-ignition trend with the H content [7]. This work was afterwards extended to different biomass samples from agriculture and forestry, cokes, solid recovered fuels, and sewage sludge, remarking the differences among the biomass materials and coals, attributing to the heat transmission mechanism the reported differences [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Effect of sewage sludge composition on the susceptibility to spontaneous combustion

Dı́az

Pintado

Faba

et al. 2019

Journal of Hazardous Materials

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The different technologies applied to the sewage sludge management have in common a first step devoted to the storage. In the case of dried sludges, this storage leads to important safety concerns because of the explosive character of the resulting dusts. In order to ensure safety in the storage step, it is necessary to evaluate the spontaneous combustion trends on terms of measurable chemical and physical properties of the dried sludges. In order to accomplish this scope, twelve samples from different wastewater treatment plants were characterized, correlating the susceptibility to spontaneous combustion with both the sludge composition and the heating value. Equations traditionally used for coals were used to determine the higher heating value from the chemical composition, finding as main source of error the high oxygen content of the sludge samples. Concerning the thermal susceptibility, different parameters were obtained (Maciejasz Index, induction temperature, maximum weight loss temperature, characteristic temperature and activation energy), being in all cases the spontaneous combustions favored by high H/C and low O/C ratios. Likewise, the presence of sulphur in the dried sludge was found to increase the thermal susceptibility of the material. This effect is tentatively explained with the formation of pyrophoric iron sulfides.

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Analysis of Spontaneous Ignition of Grass: Chemical Oxidation and Water Vapor Sorption

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2021

Fire Technol

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Self-heating of biomass by chemical oxidation, which can cause spontaneous ignition, is a safety and management concern. This process can be accelerated by aerobic fermentation and water vapor sorption. The chemical oxidation and water vapor sorption of grass were studied in a laboratory oven, measuring the variations in weight and the internal temperature of a sphere with grass within a flexible polymeric network. Both processes were simulated to prove that the proposed mathematical model could fit the experimental data. It was observed that the water vapor sorption capacity of the grass was high, so the experimental increase in the internal temperature of a spherical body was around 47 K, from 73°C to 120°C. This fact can be very important because the chemical oxidation of grass accelerates at high temperatures. For scaling, simulation programs were used to study the sorption and oxidation processes with an increase in internal temperature in spherical bodies and infinite plane slabs. These results can be used to obtain those of other geometric symmetries by interpolation. It was deduced that at 70°C and with vapor sorption, the ignition time can be around 3 days to 5 days, while without vapor sorption, the ignition times can be around 110 days to 140 days. For 35°C the ignition times with vapor sorption can be around 12 days to 18 days, while without vapor sorption the ignition times can be around 3700 days to 4500 days. These results can be of interest for warehouses of similar biomass and for forestry research and management groups of wildfires. Graphical Abstract

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Determination of spontaneous combustion of thermally dried sewage sludge

Cited by 17 publications

References 11 publications

Particle Size Influence on the Transport Classification Labels and Other Flammability Characteristics of Powders

Particle Size Influence on the Transport Classification Labels and Other Flammability Characteristics of Powders

Effect of sewage sludge composition on the susceptibility to spontaneous combustion

Analysis of Spontaneous Ignition of Grass: Chemical Oxidation and Water Vapor Sorption

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