Ignition sensitivity of solid fuel mixtures

Abstract

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.

Biocoal - Quality control and assurance

“…Further research is needed, in order to establish a novel, qualitative, rapid testing analytical techniques, such as FTIR ATR or NIR, as QC techniques for Biocoal, most of the work being the identification of particular wavenumbers/bandwidths relevant for the properties of the solid fuel. It would be even better if correlations between such characteristic wavenumbers/bandwidths and performance of the solid fuels in [193] ☑ Time-consuming Ultimate analysis � Dedicated (CHNS*) analysers ☑ Allow calculation of the stoichiometric amount of oxygen/air [181,182] ☑ Allow estimation of the change of NO x emissions ("fuel NO x ") and SO x depending on the used fuel ** [183][184][185][186][187][188][189][190] Fire and explosion characteristics � 20 L or 1 m 3 spherical vessel � Hartmann apparatus � Layer Ignition Temperature Apparatus � Self-Ignition (in volume) Temperature apparatus � Goldberg-Greenwald apparatus ☑ Parameters necessary for ATEX assessment and risk prevention (fire and explosion safety) [194] ☑ Assessment of reactivity [33,85,[195][196][197] ☑ Knowledge about ignition and flame propagation [34,[197][198][199] ☑ Time-consuming * -not all analysers allow determination of S content. ** -requires information on fuel N/S conversion to NO x /SO x .…”

Study on the Similarity of the Parameters of Biomass and Solid Waste Fuel Combustion for the Needs of Thermal Power Engineering

“…This resulted in an estimation of the ignition of the front propagation velocity in the investigated solid beds, which is of general importance in the design of grate furnaces. The dynamics of combustion in these works are discussed in terms of the physical properties of the bed, such as bulk density and porosity, etc., and we also see additional interest of the authors, e.g., in [23,24], in the phenomenon of fuel mixtures' explosion and the observation of the flame front in these processes. However, it is clearly visible, also in these works, that the data from the experiment are not related to the parameters of the boiler grate furnace on a technical scale.…”

Explosive property and combustion kinetics of grain dust with different particle sizes

“…Additionally, cereal residues as renewable and abundant resources, include both on-site residues and processing residues, have a huge potential to achieve more sustainable agriculture and to provide a novel fuel feedstock in theory [4]. However, the suspending grain dust in production departments is detrimental to life safety during liquor-making and starch processing, which holds potential hazard of fire or explosion due to its flammability and low density for forming an explosive cloud [5,6,7]. The necessary prevention and control of organic dust explosion are very imperative for safety production and property security, and the quantitative research on the potential explosion property is the prerequisite to designing some effective and efficient safeguards to minimize its security risk.…”

“…Saeed et al [16,17] suggest that fine biomass facilitates increased mass-burning with high flame speed. Therefore, the potential risk derived from the organic dust including explosion and ignition imparts huge hidden danger to the dust-processing workshops [5,6,7]. The preliminary exploration of the ordinary or pristine organic dust is necessary to broaden the combustion and explosion mechanism, which is beneficial to provide some basic experimental data in the security design of dust explosion suppression.…”