32 results found
Restuccia F, Fernandez-Anez N, Rein G, 2019, Experimental measurement of particle size effects on the self-heating ignition of biomass piles: Homogeneous samples of dust and pellets, Fuel, Vol: 256, ISSN: 0016-2361
Biomass can become an important fuel source for future power generation worldwide. However biomass piles are prone to self-heating and can lead to fire. When storing and transporting biomass, it is usually in the form of pellets which vary in diameter but are on average in the order of 7 mm. However, pellets tend to break up into smaller particles and into dust down to the µm size. For self-heating, size of particles is known to matter but the topic is poorly studied for biomass piles. This work presents an experimental study on the self-heating ignition behaviour of different particle sizes of wheat biomass. We study for the first time homogeneous samples from the dust scale to pellet diameter size, ranging from diameters of 300 µm to 6.5 mm. Experiments are done in an isothermal oven to find minimum ignition temperatures as a function of sample volume. The results are analysed using Frank-Kamenetskii theory. For the homogeneous biomass samples studied, we show that particle diameter variation does not bring a large change in self-heating ignition behaviour. The present work can be used to help quantify size effects on biomass ignition and help address the safety problems of biomass fires.
Fernandez-Anez N, Garcia-Torrent J, 2019, Influence of Particle Size and Density on the Hot Surface Ignition of Solid Fuel Layers, FIRE TECHNOLOGY, Vol: 55, Pages: 175-191, ISSN: 0015-2684
© 2018 Elsevier Ltd Due to both environmental concerns and the depletion of the reserves of fossil fuels, alternative and more environmentally friendly fuels, such as biomass and waste products, are being considered for partial or full fossil fuel replacement. The main disadvantage of these products is their lower energy density compared to fossil fuels. To deal with this several heat and power generation facilities are co-firing fuel mixtures. These processes involve mixtures of flammable dusts whose ignitability and explosibility characteristics are not known and therefore present un-quantified safety risk to the new technologies. This study reports on these risks and on the reactivity characteristics of two and three components dust mixtures of coal/sewage-sludge/torrefied-wood-pellet. In particular chemical composition, ignition sensitivity parameters (including minimum ignition energy, minimum ignition temperature on a layer, minimum explosive concentration) and flame speed have been determined. In all cases the measured parameters for the mixtures were within the range defined by the lower and upper value of the constituent. However, the expected values do not agree with the experimentally obtained ones, providing more relaxed values than the ones needed on this facilities.
Hu Y, Fernandez-Anez N, Smith TEL, et al., 2018, Review of emissions from smouldering peat fires and their contribution to regional haze episodes, International Journal of Wildland Fire, Vol: 27, Pages: 293-312, ISSN: 1049-8001
Smouldering peat fires, the largest fires on Earth in terms of fuel consumption, are reported in six continents and are responsible for regional haze episodes. Haze is the large-scale accumulation of smoke at low altitudes in the atmosphere. It decreases air quality, disrupts transportation and causes health emergencies. Research on peat emissions and haze is modest at best and many key aspects remain poorly understood. Here, we compile an up-to-date inter-study of peat fire emission factors (EFs) found in the literature both from laboratory and from field studies. Tropical peat fires yield larger EFs for the prominent organic compounds than boreal and temperate peat fires, possibly due to the higher fuel carbon content (56.0 vs 44.2%). In contrast, tropical peat fires present slightly lower EFs for particulate matter with diameter ≤2.5 μm (PM2.5) for unknown reasons but are probably related to combustion dynamics. An analysis of the modified combustion efficiency, a parameter widely used for determining the combustion regime of wildfires, shows it is partially misunderstood and highly sensitive to unknown field variables. This is the first review of the literature on smouldering peat emissions. Our integration of the existing literature allows the identification of existing gaps in knowledge and is expected to accelerate progress towards mitigation strategies.
Fernandez-Anez N, Christensen K, Rein G, 2017, Two-dimensional model of smouldering combustion using multi-layer cellular automaton: The role of ignition location and direction of airflow, Fire Safety Journal, Vol: 91, Pages: 243-251, ISSN: 0379-7112
Smouldering combustion is one of the most common and persistent fire hazards of reactive porous media, such as biomass. In this work, a two-dimensional multi-layer cellular automaton has been developed to study the process of smouldering and the roles of both the ignition location and the direction of airflow for generic biomass. Three different configurations are studied: line front, with forward and opposed airflow respectively, and radial front. The first two configurations simulate ignition of one edge of the sample, while the radial front simulates ignition of a spot at the centre of the sample. The resulting spread patterns of line vs. radial front are significantly different. Furthermore, when smouldering occurs with similar characteristics, where both line front and radial front are self-sustained, the smouldering radial front has a higher growth rate than the line front. However, in the studied cases where enough oxygen is always available for oxidation, the direction of the airflow does not influence the spread of the smouldering front, and the line front with forward and opposed airflow present similar behaviour. Finally, two non-zero minimum values have been detected for self-sustained spread according to the moisture of the fuel (probability of drying) and its tendency for thermal degradation (probability of pyrolysis). This model provides a powerful but simple way of reproducing the complex dynamics of smouldering processes which can be used to investigate different scenarios.
Novak VM, Fernandez-Anez N, Shiraishi K, 2017, Rethinking resilience planning: from problems to potential, International Journal of Disaster Resilience in the Built Environment, Vol: 8, Pages: 412-424, ISSN: 1759-5908
© 2017, © Emerald Publishing Limited. Purpose: Planning for the future can become mired in fixing the problems of the present. To create alternative solutions, planning must break free of the boundaries and assumptions of existing paradigms. The purpose of this paper is to explore an alternative way of thinking that reframes the issues from problems of “what is” to the potential of “what could be” in the context of socio-ecological resilience. Design/methodology/approach: A case study reviews the limitations revealed during a traditional problem-solving exercise on the topic of Coastal Eco-Cities, as well as the innovations resulting from the rethinking of the issues through the lens of the alternative paradigm. Findings: A key finding is the significance of linguistic modality, shifting from objective expressions to subjective dialogue. Originality/value: The originality of this approach is the emphasis on the framing of the problem before the development of the solution and the methodological implications of this early dialogue.
García Torrent J, Ramírez-Gómez Á, Fernandez-Anez N, et al., 2016, Influence of the composition of solid biomass in the flammability and susceptibility to spontaneous combustion, Fuel, Vol: 184, Pages: 503-511, ISSN: 0016-2361
© 2016 Biomasses are materials highly demanded nowadays for energy production. One of the main features of these materials is that they present a great variability in terms of chemical composition and physical behavior (O/C and H/C ratios, granulometric structure, ash content…). Nowadays, there is a lack of information concerning its characterization to determine its flammability and explosibility behavior. The objective of this study is to provide flammability and explosibility data as well as some parameters to assess the spontaneous combustion tendency of these products and to relate this thermal susceptibility with the composition. Initial results showed that risk assessments based on the activation energy were not effective for biomass as it is for coals, and that a greater tendency to self-ignition was observed in those biomasses having higher H/C ratios, on the contrary than in coals. This behavior can be explained because the most important stage for coals is the beginning of the self-heating reaction, which present a different resistance (activation energy) depending on its ranking, while biomasses present an initial stage easily achievable even at moderate temperatures, so the differentiation for biomasses should be found in the ability to spread this incipient reaction.
Medic-Pejic L, Fernandez-Anez N, Rubio-Arrieta L, et al., 2016, Thermal behaviour of organic solid recovered fuels (SRF), International Journal of Hydrogen Energy, ISSN: 0360-3199
The determination of the safety conditions in the storage and handling of solid recovered fuels (SRFs) was evaluated in order to avoid the presence of explosive atmospheres. Ten SRF samples were selected from different solid waste streams and collected in different seasons and different locations in Spain.Four different testing methodologies for characterizing the SRF dusts were carried out in order to determine thermal susceptibility and flammability. By means of thermogravimetric techniques, differential scanning calorimetry, minimum ignition energy and minimum ignition temperature on a cloud tests it has been possible to analyse the thermal susceptibility and ignition sensibility of SRFs. A prediction of the self-ignition risk level has been also obtained by a graphical method thanks to the data obtained.
Garcia-Torrent J, Fernandez-Anez N, Medic-Pejic L, et al., 2016, Ignition and explosion parameters of Colombian coals, Journal of Loss Prevention in the Process Industries, ISSN: 0950-4230
The explosivity of coal in Colombia is usually determined by chemical analysis based on the volatile ratio. To improve the assessment of the explosivity of those coals that have led to numerous explosions in Colombian mines, 22 coals from the department of Antioquia were analyzed. Flammability characteristic parameters were determined, such as minimum temperatures and energy for ignition and the lower explosive limit. Also explosion data, ie. Pmax and Kmax values were obtained. In addition, the susceptibility to spontaneous combustion was studied by thermogravimetry and differential scanning calorimetry, together with chemical attack with hydrogen peroxide and also measuring the temperature of ignition of flammable volatiles. Finally the effect of particle size and the percentage range of limestone needed for inerting coal under two different granulometries were determined.
Fernandez Anez N, 2016, Analysis of the flammability properties of solid fels
Fernandez Anez N, Bolonio Martin D, Medic Pejic L, et al., Facebook and fuels: an academic use, III Congreso Internacional sobre Aprendizaje, Innovacion y Competitividad
Medic Pejic L, Fernandez Anez N, Garcia Torrent J, et al., 2015, Determination of spontaneous combustion of thermally dried sewage sludge, JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES, Vol: 36, Pages: 354-359, ISSN: 0950-4230
Fernandez Anez N, Garcia Torrent J, Medic Pejic L, et al., 2015, Detection of incipient self-ignition process in solid fuels through gas emissions methodology, JOURNAL OF LOSS PREVENTION IN THE PROCESS INDUSTRIES, Vol: 36, Pages: 345-353, ISSN: 0950-4230
Medic Pejic L, Rubio Arrieta L, Al-Lal Baeza A, et al., Characterization of different solid recovered fuels (SRF), 10th European Congress of Chemical Engineering
Fernandez Anez N, Medic Pejic L, Garcia Torrent J, et al., Flammability properties of co-firing fuel mixtures, 10th European Congress of Chemical Engineering
Molina Escobar JM, Blandon Montes A, Caro Gonzalez L, et al., Characterization of flammability and explosibility properties of Colombian coals, 10th European Congress of Chemical Engineering
Fernandez Anez N, Slatter DJF, Saeed MA, et al., Ignition sensitivy of coal / waste / biomass mixtures, 8th International Conference on Sustainable Energy & Environmental Protection
Medic Pejic L, Rubio Arrieta L, Fernandez Anez N, et al., Thermal susceptibility of solid recovered fuels, 8th International Conference on Sustainable Energy & Environmental Protection
Fernandez Anez N, Dameto de Espana N, Garcia Torrent J, et al., Ignition of waste/biomass mixtures deposited as dust layers, 25th International Colloquium on the Dynamics of Explosions and Reactive Systems
Torrent JG, Anez NF, Pejic LM, et al., 2015, Assessment of self-ignition risks of solid biofuels by thermal analysis, FUEL, Vol: 143, Pages: 484-491, ISSN: 0016-2361
Medic-Pejic L, Garcia-Torrent J, Fernandez-Añez N, et al., 2015, Experimental study for the application of water barriers to Spanish small cross section galleries, DYNA (Colombia), Vol: 82, Pages: 142-148, ISSN: 0012-7353
© The author; licensee Universidad Nacional de Colombia. The objective of this work is the implementation of passive water trough barriers to put in practice EN-14591-2:2007 standard, as well as an update of the continuing study of passive water barriers. The viability of water barriers in typical Spanish small cross section galleries was analyzed and full scale testing at “Barbara” experimental mine in Poland was carried out. Suggestions for proper implementation of standards in Spain are presented.
Fernandez-Anez N, Garcia-Torrent J, Medic-Pejic L, 2014, Flammability properties of thermally dried sewage sludge, FUEL, Vol: 134, Pages: 636-643, ISSN: 0016-2361
Fernandez Anez N, Garcia Torrent J, Medic Pejic L, et al., Influence of grain size and compaction of different solid fuels on the layer ignition temperature, II International Symposium on Handling and Hazards of Materials in Industry
Fernandez Anez N, Medic Pejic L, Garcia Torrent J, et al., Characterization of gas emissions during heating of solid products, II International Symposium on Handling and Hazards of Materials in Industry
Fernandez Anez N, Garcia Torrent J, Medic Pejic L, et al., New tests for the detection of incipient self-ignition process in solid fuels, Tenth International Symposium on Hazards, Prevention, and Mitigation of Industrial Explosions
Medic Pejic L, Fernandez Anez N, Montenegro Mateos L, et al., Characterization of spontaneous combustion tendency of dried sewage sludge, Tenth International Symposium on Hazards, Prevention, and Mitigation of Industrial Explosions
Fernandez Anez N, Alvarez Perez A, Garcia Torrent J, et al., Explosion risk in coke, coal and sulphur storage, XIII International Conference on Energy and Mineral Resources
Garcia Torrent J, Fernandez Anez N, Medic Pejic L, et al., 2013, Guia sobre la operacion segura de las plantas con secado termico de lodos en las depuradoras de aguas residuales, Publisher: Fundacion Gomez Pardo, ISBN: 9788469581698
Fernandez Anez N, Montenegro Mateos L, Medic Pejic L, et al., Flammability properties of dry sewage sludges, 13th International Multidisciplinary Scientific Geoconference SGEM 2013, ISSN: 1314-2704
Montenegro Mateos L, Garcia Torrent J, Castilla Gomez J, et al., Physical characteristics of biomass and its influence in self-combustion, 13th International multidisciplinary scientific geoconferences SGEM 2013, ISSN: 1314-2704
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