Post-combustion Zone Research Articles

Influence of fire-ignition methods and stove ventilation rates on gaseous and particle emissions from residential coal braziers

Despite extensive electrification of low-income residential areas on the South African Highveld, extensive use is still made of wood and coal as domestic fuels, particularly for winter space heating. In informal settlements characterised by poverty and lacking electrification, coal is combusted in non-standardised, inefficient and polluting metal braziers, colloquially known as imbaulas. Copious emissions from domestic coal fires result in elevated household and ambient air pollution levels well above national air quality limits. Despite the severity of this pollution as a public health issue, emissions data from residential coal-burning braziers are still scarce. Consequently, there is a need to evaluate the emission characteristics of these devices. In this paper, we report on controlled combustion experiments carried out to investigate systematically influences of fire-ignition methods and stove ventilation rates on gaseous and condensed matter (smoke) emissions from informal residential coal combustion braziers. Two methods of stove ignition—conventional bottom-lit updraft (BLUD) and the top-lit updraft (TLUD) (colloquially known as the Basa njengo Magogo) were investigated. Emission factors (EFs) were found to be dependent on fire ignition method and stove ventilation rates. The top-lit ignition method reduces PM10/PM2.5 by 76% to 80% compared to the BLUD method. Carbon monoxide emissions do not change significantly with the ignition method. Pollutant emissions from normal combustion in high ventilation conditions were low compared to pollutants emitted when an oxygen deficient atmosphere was created under low ventilation conditions. High stove ventilation rates resulted in a 50% reduction in PM10/PM2.5 emissions compared to the low ventilation rates. Emissions of gaseous and particulate matter from incomplete combustion can be minimised by design optimisation of the braziers. Ideally, the emissions of condensed matter particles (which form the bulk of emitted particles in residential coal fires) can be reduced through good mixing of emitted gases and air, and by ensuring a long residence time in the high temperature oxygen rich post combustion zone, to allow for complete oxidation. This study is significant in that it presents the first systematic and comprehensive study of factors affecting emissions from coal braziers.

Influence of fire-ignition methods and stove ventilation rates on gaseous and particle emissions from residential coal braziers

Despite extensive electrification of low-income residential areas on the South African Highveld, extensive use is still made of wood and coal as domestic fuels, particularly for winter space heating. In informal settlements characterised by poverty and lacking electrification, coal is combusted in non-standardised, inefficient and polluting metal braziers, colloquially known as imbaulas. Copious emissions from domestic coal fires result in elevated household and ambient air pollution levels well above national air quality limits. Despite the severity of this pollution as a public health issue, emissions data from residential coal-burning braziers are still scarce. Consequently, there is a need to evaluate the emission characteristics of these devices. In this paper, we report on controlled combustion experiments carried out to investigate systematically influences of fire-ignition methods and stove ventilation rates on gaseous and condensed matter (smoke) emissions from informal residential coal combustion braziers. Two methods of stove ignition—conventional bottom-lit updraft (BLUD) and the top-lit updraft (TLUD) (colloquially known as the Basa njengo Magogo) were investigated. Emission factors (EFs) were found to be dependent on fire ignition method and stove ventilation rates. The top-lit ignition method reduces PM10/PM2.5 by 76% to 80% compared to the BLUD method. Carbon monoxide emissions do not change significantly with the ignition method. Pollutant emissions from normal combustion in high ventilation conditions were low compared to pollutants emitted when an oxygen deficient atmosphere was created under low ventilation conditions. High stove ventilation rates resulted in a 50% reduction in PM10/PM2.5 emissions compared to the low ventilation rates. Emissions of gaseous and particulate matter from incomplete combustion can be minimised by design optimisation of the braziers. Ideally, the emissions of condensed matter particles (which form the bulk of emitted particles in residential coal fires) can be reduced through good mixing of emitted gases and air, and by ensuring a long residence time in the high temperature oxygen rich post combustion zone, to allow for complete oxidation. This study is significant in that it presents the first systematic and comprehensive study of factors affecting emissions from coal braziers.

Air staging strategies in biomass combustion-gaseous and particulate emission reduction potentials

Gaseous and particulate emissions have been investigated with different air staging strategies over a wide range of secondary air flow rates. Laboratory scale wood pellet combustor, supplied by an underfeed fuel bed input, is used. The air staging strategies have been employed to study burning rate, temperature in primary and post combustion zones, and NO, CO and PM emissions, taking into account the air to fuel stoichiometric ratio. 50% CO reduction and 9 times less particle mass concentration than non-staged combustion are achieved by deploying a uniform secondary air module in a higher position from the bed. The minimum NO (37% reduction than non-staged) measured in the non-uniform air distribution module at the higher flow rate with lower distance from the fuel bed. The results demonstrate a trade-off between NO and CO, PM emissions but also significant potential for reducing particulate and gaseous emissions by deploying air staging in the pellet combustor.

An experimental study into the effect of air staging distribution and position on emissions in a laboratory scale biomass combustor

Air staging strategy is a proven technology to provide efficient biomass combustion with less gaseous and particulate emissions. In this study, two different secondary air distribution modules are employed at two different axial positions from the bed surface in a 15 kW fixed-bed laboratory scale combustion system includes grate and underfeed bed stocker. The effects of air staging on temperature, burning rate, gaseous and particulate emissions have been assessed over a selected primary air flow rate and a range of secondary air flow rates. Secondary air inlet module with uniform distribution of air results in 50% CO reduction by shifting the combustion to a more fuel lean environment and high temperature in the post-combustion zone. Remarkable decrease in particulate matters smaller than 1 μm is achievable through adjusting a uniform secondary air module in an appropriate distance from the bed. The non-uniform secondary air configuration increases the gaseous and particulate emissions than the uniform configuration. These results emphasise the need for further studies to better understand the effect of air staging on particulate and gaseous emissions.

Suppression of dioxins after the post-combustion zone of MSWIs

Thiourea was selected as representative of combined S- and N-inhibitors and injected after the post-combustion zone of two full-scale municipal solid waste incinerators (MSWIs) using a dedicated feeder. Firstly, the operating conditions were scrutinised by monitoring the concentrations of SO2, NH3 and HCl in the clean flue gas. The suppression experiment showed that in MSWI A thiourea could reduce the total I-TEQ value in flue gas by 73.4% from 1.41ng I-TEQ/Nm3 to 0.37I-TEQ/Nm3, those in fly ash by 87.1% from 14.3ng I-TEQ/g to 1.84I-TEQ/g and the total dioxins emission factor by 87.0wt.%, with a (S+N)/Cl molar ratio of 9.4. The suppression efficiencies of PCDD/Fs in flue gas and fly ash in MSWI B could be up to 69.2% and 83.0% when the (S+N)/Cl molar ratio attained 7.51. Furthermore, the congener distributions of dioxins were also analysed in the flue gas and fly ash, before and after addition of thiourea, to find cues to some suppression mechanism. In addition, the filtered fly ash was explored by the Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS) analysis of fly ash. These results suggest that poisoning the metal catalyst and blocking the chlorination are most probably responsible for suppression.

ON THE PROBLEMS OF CONTROL AND REDUCTION OF HIGH-TEMPERATURE LOSS OF STEEL IN HEATING FURNACES

The problem of assessment of the steel loss in the thickness of scale is considered for industrial furnaces. The possibilities of different ways to reduce steel oxidation are analyzed. Particular attention is paid to the attendant diffi culties of decrease of steel loss by reducing the oxidant consumption coeffi cient (n). The reality of achievement of substantially nonoxidative steel heating in industrial furnaces at present is shown. The author has highlighted their important technological characteristics: almost molecular mixing of the primary components of combustion (natural gas at n = 0.48 – 0.5), the synchronicity of the burners work and limit n deviation at regulation of primary combustion of fuel Δn ≤ 0,01, the eff ective jet-mechanical throttling of primary gas flow precluding the reverse circulation of the primary products of incomplete combustion from the post-combustion zone to the metal heating zone. Directions of design and work options of forging and rolling furnaces are proposed with the achievement of the relevant indicators for the reduction or complete suppression of steel loss. The problems of internal high-temperature oxidation of silicon of transformer steel are particularly analyzed as well as the nondecarburization heating of ball-bearing steel

Influence of simulated MSW sizes on the combustion process in a fixed bed: CFD and experimental approaches

This work presents the effect of the simulated sizes of Municipal Solid Waste (MSW) on the combustion process in a fixed bed experimentally and numerically. The effect of temperature, gas emissions, flame front velocity and process rate are discussed for three different sizes of MSW: 10, 30, and 50mm. The study found that for the operating conditions of the current model, when the diameter of particles is decreased, the bulk density of the material is increased, resulting in a decrease of convective heat transfer as well as combustion speed. As the diameter size of the material particles increase, the height of the post-combustion zone is increased, while the temperature in a high temperature area is decreased, due to the decrease in the material’s bulk density and the excessive increase in porosity. Results also show that the average emission concentration of CO and CO2 decreases gradually with an increase in the particle diameter size.

Investigation of the effects of quarl and initial conditions on swirling non-premixed methane flames: Flow field, temperature, and species distributions

Detailed measurements are presented of the turbulent flow field, gas species concentrations and temperature field in a non-premixed methane swirl flame. Attention is given to the effect of the quarl geometry on the flame structure and emission characteristics due to its importance in gas turbine and industrial burner applications. Two different quarls were fitted to the burner exit, one a straight quarl and the other a diverging quarl of 15° half cone angle. Stereoscopic Particle Image Velocimetry (SPIV) was applied to obtain the three components of the instantaneous velocity on a vertical plane immediately downstream of the quarl exit. Temperature and gaseous species measurements were made both inside and downstream of the quarls, using a fine wire thermocouple and sampling probe, respectively. This work provides experimental verification by complementary techniques. The results showed that although the main flame structures were governed by the swirl motion imparted to the air stream, the quarl geometry, fuel loading and air loading also had a significant effect on the flow pattern, turbulence intensity, mixture formation, temperature distribution, emissions and flame stabilization. Particularly, in the case of the straight quarl flame, the flow pattern leads to strong, rapid mixing and reduces the residence time for NO formation within the internal recirculation zone (IRZ). However, for the diverging quarl flames, the recirculation zone is shifted radially outward, and the turbulent interaction between the central fuel jet and the internal recirculation zone IRZ induces another small vortex between these two flow features. Less mixing near the diverging quarl exit is observed, with a higher concentration of NO and CO in the post-combustion zone. The instantaneous flow field for both flames showed the existence of small scale vortical structure near the shear layers which were not apparent in the time averaged flow field. These structures, along with high levels of turbulence present in the shear layer, result in the enhancement of the mixing, especially with straight quarl. This article outlines results that yield deeper insight into the combustion of swirling flames stabilized within the quarl and to establish an experimental data base for modelers.

The role of CuCl on the mechanism of dibenzo-p-dioxin formation from poly-chlorophenol precursors: A computational study.

A computational study is performed for the elucidation of the role played by CuCl in the condensation of two polychlorophenol molecules to yield PCDDs. The mechanism found consists of six sequential steps, which allow the final recuperation of the CuCl molecule, and applies for phenol molecules with an ortho chlorine. In the temperature range of 453-473 K (previously reported as adequate to diminish PCDDs formation in the post-combustion area), CuCl is able to softly retain chlorophenol molecules, mainly those less chlorinated. After a first HCl release, Cu(I) remains bonded to phenol oxygen atom, thus avoiding the formation of phenoxy radicals and the subsequent radical processes. A temperature raise up to 1200 K destabilizes the initial CuCl-chlorophenol complexes and causes that the rate limiting step change from the formation of the first oxygen bridge to HCl elimination. It has been checked that tetra and penta-chlorophenols undergo essentially the same reaction process of 2-chlorophenol. In view of our results and trying to arrive at a practical way to diminish the rate of formation of PCDDs, we propose that an extra addition of powdered CuCl to the post-combustion zone, cooled down to temperatures lower than 473 K, could act as an inhibitor in the formation of these pollutants.

Behavior and Fate of Halloysite Nanotubes (HNTs) When Incinerating PA6/HNTs Nanocomposite.

Nanoclay-based nanocomposites have been widely studied and produced since the late 1990s, and frequently end up in waste disposal plants. This work investigates the behavior of PA6/HNTs nanocomposites (nylon-6 incorporating halloysite nanotubes) during incineration. Incineration tests were performed at lab-scale using a specific tubular furnace modified in order to control the key incineration parameters within both the combustion and postcombustion zones. The combustion residues and combustion aerosol (particulate matter and gas phase) collected downstream of the incinerator furnace were characterized using various aerosol analysis techniques. Time tracking of the gas and particle-number concentrations revealed two-step char formation during combustion. HNTs transformed into other mineral structures which were found in both the aerosol and the residues. During combustion of the polymer, it appears that HNTs contribute to the formation of a cohesive char layer that protects the residual material.

Production of ultra-high temperature carbide (Ta,Zr)C by self-propagating high-temperature synthesis of mechanically activated mixtures

The combustion temperatures and rates of mechanically activated (MA) Ta–Zr–C mixtures depending on the initial temperature T0 are determined. The self-heating phenomenon is observed in argon atmosphere at T0>380K due to oxidation of the surface of zirconium particles by adsorbed oxygen. Zirconium oxide is formed in the combustion zone at the initial stage of chemical interaction; it is subsequently transformed into zirconium carbide. In addition, tantalum carbide is formed in the combustion zone, while the binary tantalum–zirconium carbide (Ta,Zr)C is formed closer to the post-combustion zone. In order to maintain the layer by layer stationary combustion mode of SHS, the initial temperature T0 needs to be 298K, while the duration of mechanical activation needs to be less than 5min. After longer mechanical activation, the mixtures are prone to bulk combustion even at low initial temperatures. Single-phase (Ta,Zr)C carbide with the lattice parameter of 0.4479nm was synthesized by forced SHS compaction in a sand mold.

PCDD/Fs’ suppression by sulfur–amine/ammonium compounds

Three distinct –S and –NH2 or NH4+ containing compounds, including ammonium thiosulfate, aminosulfonic acid and thiourea, were studied as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) inhibitors. All these three –S and –N containing compounds tested show strong suppression of PCDD/Fs formation, especially for thiourea which has not been studied before. With a (S+N)/Cl molar ratio of only 0.47, thiourea could inhibit 97.3% of PCDD/Fs and even 99.8% of I-TEQ. At an unusually high de novo test temperature (650°C), the PCDD/Fs’ formation was still very low but also the inhibition capacity of thiourea was weak, with an efficiency of 59% for PCDD/Fs when with a (S+N)/Cl molar ratio of 1.40. The results also revealed that the inhibition capability of the combined –S/–NH2 or –S/NH4+ suppressant was strongly influenced by both the nature of the functional group of nitrogen and the value of the molar ratio (S+N)/Cl. The amine functional group –NH2 tends to be more efficient than ammonium NH4+ and within a certain range a higher (S+N)/Cl value leads to a higher inhibition efficiency. Moreover, the emission of gases was continuously monitored: the Gasmet results revealed that SO2, HCN and NH3 were the most important decomposition products of thiourea. Thiourea is non-toxic, environment-friendly and can be sprayed into the post-combustion zone in form of powder or aqueous solution. The cost of thiourea at least can be partially compensated by its high inhibition efficiency. Therefore, the application of thiourea in a full-scale incinerator system is promising and encouraging.

Effect of CaO on retention of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W and Pb in bottom ashes from fluidized-bed coal combustion power station

This work was conducted to evaluate whether Ca-bearing additives used during coal combustion can also help with the retention of some other elements. This work was focused on the evaluation of bottom ashes collected during four full-scale combustion tests at an operating thermal fluidized-bed power station. Bottom ashes were preferred to fly ashes for the study to avoid interference from condensation processes usually occurring in the post-combustion zone. This work focused on the behaviors of S, Cl, Br, As, Mn, V, Cr, Ni, Cu, Zn, W, and Pb. Strong positive correlations with CaO content in bottom ashes were observed (for all four combustion tests) for S, As, Cl and Br (R=0.917–0.999). Strong inverse proportionality was calculated between the contents of Pb, Zn, Ni, Cr and Mn and CaO, so these elements showed association to materials other than Ca-bearing compounds (e.g., to aluminosilicates, organic matter, etc.). Somewhat unclear behaviors were observed for W, Cu, and V. Their correlation coefficients were evaluated as statistically “not significant”, i.e., these elements were not thought to be significantly associated with CaO. It was also discovered that major enrichment of CaO in the finest bottom ash fractions could be advantageously used for simple separation of elements strongly associated with these fractions, mainly S and As, but also Cl or Br. Removal of 5% of the finest ash particles brings about a decrease in As concentration down to 77%–80% of its original bulk ash content, which can be conveniently used e.g., when high As content complicates further ash utilization.

Towards controlling PCDD/F production in a multi-fuel fired BFB boiler using two sulfur addition strategies. Part I: Experimental campaign and results

Levels of PCDD/F production in a 140MWth bubbling fluidized bed boiler were measured. The boiler uses solid recovered fuel, bark and sludge. Homologue distribution patterns suggest the de novo mechanism is the main pathway for the generation of dioxin and furans in the post combustion zones of the boiler. Two modes of sulfur addition were tested to induce the deactivation of Cu which has been identified as the prime catalyst of this mechanism. First, S-pellet promoted Cu sulfation as supported by aerosol sampling data and resulted in a decrease in PCDD/F levels. The second approach was adding sulfur through peat; this resulted in an increase in PCDD/F concentration. Factors such as high Cu content in the SRF-peat-sludge fuel mixture and reduced volatilization of Cu may have contributed to the said increase. For all test cases, phase redistribution of PCDD/F was observed in the electrostatic precipitator favoring more gaseous PCDD/F at the outlet. The homologue distribution pattern did not change in the flue gas path, suggesting that further synthesis and/or chlorination in the stream were minimized. There is however evidence for subsequent reactions happening in the ESP fly ash. The homologue distribution pattern in the latter was different from that of the flue gas, and more highly chlorinated PCDD/Fs were present. Furthermore, the ratio of PCDD and PCDF was different from that of the samples in the flue gas path.

Polychlorinated Dibenzo-P-Dioxins and Dibenzofurans from a Grate-Type Municipal Solid Waste Incinerator in China

The emission characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were evaluated from a grate-type municipal solid waste incinerator (MSWI). The stack flue gas, fly ash and bottom ash samples were sampled and analyzed. Results indicated that the flue gas, fly ash and bottom ash presented their mean dioxin levels of 0.0723 ng I-TEQ/Nm3, 0.614 ng I-TEQ/g and 13.33 ng I-TEQ/kg respectively. The PCDD/Fs congener patterns, in flue gas, fly ash and bottom ash, showed large similarities in both concentration and I-TEQ profiles. The de novo synthesis plays a dominant role in the low-temperature post-combustion zone.

Temperature Measurement in WTE Boilers Using Suction Pyrometers

The temperature of the flue-gas in the post combustion zone of a waste to energy (WTE) plant has to be maintained within a fairly narrow range of values, the minimum of which is prescribed by the European Waste Directive 2000/76/CE, whereas the maximum value must be such as to ensure the preservation of the materials and the energy efficiency of the plant. A high degree of accuracy in measuring and controlling the aforementioned temperature is therefore required. In almost the totality of WTE plants this measurement process is carried out by using practical industrial thermometers, such as bare thermocouples and infrared radiation (IR) pyrometers, even if affected by different physical contributions which can make the gas temperature measurements incorrect. The objective of this paper is to analyze errors and uncertainties that can arise when using a bare thermocouple or an IR pyrometer in a WTE plant and to provide a method for the in situ calibration of these industrial sensors through the use of suction pyrometers. The paper describes principle of operation, design, and uncertainty contributions of suction pyrometers, it also provides the best estimation of the flue-gas temperature in the post combustion zone of a WTE plant and the estimation of its expanded uncertainty.

Multivariate relationships between molecular descriptors and isomer distribution patterns of PCBs formed during household waste incineration

The congener-specific concentrations of mono- to deca-chlorinated biphenyls (PC1-10B) in post-combustion zone flue gases from a laboratory-scale fluidized bed reactor were evaluated and correlated with a set of physicochemical properties and chlorine substitution descriptors. The objective was to identify parameters that affect post-combustion zone polychlorinated biphenyl (PCB) formation and interpreting observed correlations by using principal component analysis (PCA), and bidirectional orthogonal projections to latent structures (O2PLS). Both physicochemical variables and chlorine substitution descriptors were shown to have significant effects on the PCB congener distribution; however, the physicochemical descriptors were more influential in all-homologue models, whereas the chlorine substitution descriptors had a greater impact in single-homologue models, which suggests that PCB formation in general may be under thermodynamic control, whereas the distribution of isomers within homologues is more sensitive to chlorine substitution parameters. The EHOMO and ELUMO variables notably influenced both the PCA and the O2PLS models, which indicate that reactivity and polarization in the molecular structures of the PCBs is of importance.

Destruction and formation of dioxin-like PCBs in dedicated full scale waste incinerators

Destruction and formation of dioxin-like PCBs in full scale waste incinerators is studied by analysing input waste streams and boiler and fly ash of a grate furnace incinerator (GFI) incinerating MSW, of a Fluidised Bed Combustor (FBC) incinerating a mix of 50% sludge, 25% refuse derived fuel (RDF) and 25% automotive shredder residue (ASR) and of a rotary kiln incinerator (RKI) incinerating hazardous waste. The dioxin-like PCB fingerprints of the waste inputs show that PCB oils Aroclor 1242 and Aroclor 1254 late are the major dioxin-like PCB contamination source of sludge, RDF and ASR. The dioxin-like PCB fingerprints of the waste inputs are clearly different from the fingerprints of the outputs, i.e. boiler and fly ash, indicating that in full scale waste incinerators dioxin-like PCBs in the input waste are destroyed and other dioxin-like PCBs are newly formed in the post combustion zone. The dioxin-like PCB fingerprint of boiler and fly ash of all three incinerators corresponds well to the fly ash fingerprint obtained in lab scale de novo synthesis experiments, indicating that dioxin-like PCBs are mainly formed through this mechanism. The high PCB concentration in the input waste mix of the RKI does not promote the formation of dioxin-like PCBs through precursor condensation.

Effects of regional differences in waste composition on the thermal formation of polychlorinated aromatics during incineration

Two artificial wastes (A and B) whose contents reflect regional differences in municipal solid waste composition, were used to investigate the thermal formation of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), and naphthalenes (PCNs) during incineration. Flue gas samples were simultaneously collected at three ports in the post-combustion zone corresponding to flue gas temperatures of 400, 300, and 200°C. The combustion of Waste B, which had a higher chlorine and metal content than Waste A, produced greater levels of highly-chlorinated homologues, as demonstrated by a higher degree of chlorination. The total concentrations of PCDDs, PCDFs, PCBs, and PCNs formed in the combustion of both wastes increased as temperature decreased along the convector. There were no significant differences in total concentrations between Waste A and Waste B combustion at specific temperatures, with exception of PCDFs at 400°C. Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) modeling, used to evaluate the data for all compound groups, suggest that during flue gas quenching at temperatures of 400°C low-chlorinated homologues are preferentially formed in the presence of copper, which is known to be a very active catalyst for this process. At 300 and 200°C, the formation of highly-chlorinated homologues is favored.

The effect of combustion temperature on coal ash fine-fragmentation mode formation mechanisms

Ash particles smaller than 2.5μm in pulverized coal combustion ash are difficult to capture in particulate control devices and may pose greater harm to human health than larger particles if emitted into the atmosphere. The fine fragment coal ash mode, centered around 2μm, is less well understood than larger coarse and smaller ultrafine ash. Proposed formation mechanisms include bursting, shedding, or fragmenting of larger particles; particle-to-particle impaction; and adjunct particle formation. Increased heating rate may increase bursting and shedding of large particles and an increased overall temperature may lead to increased mineral vaporization, condensation, and subsequent merging into fine fragment particles. This study aimed at exploring these effects by varying the combustion temperature while maintaining a nearly constant residence time.Pulverized Illinois #6 bituminous coal was combusted at three different peak combustion temperatures in a self-sustaining downflow combustor operated at 15kW to generate ash, resulting in incremental temperature/residence time profiles following the same general trend. The size segregated ash samples were collected from the post-combustion zone in a Dekati low pressure inertial impactor. The mass of each fraction was measured and the ash was analyzed using scanning electron microscopy and X-ray microanalysis. The fine fragment mode ash types were classified into char, coarse, agglomerates, fragments, multi-spheres, and odd/unidentifiable classes. The abundance of these particle types were used to evaluate the significant fine fragment ash formation mechanisms and determine potential impacts of heating rate/temperature on fine-fragment particle formation. The results revealed that the mass fraction of multi-sphere, fragments, char, and agglomerates all increase with decreasing temperature. Further, there appears to be multiple formation mechanisms responsible for the generation of fine fragment sized multi-sphere and fragment type particles.