Pine Wood Combustion Research Articles

Distribution of environmentally persistent free radicals in size-segregated PMs emitted from residential biomass fuel combustion

Environmentally persistent free radicals (EPFRs) are considered as an emerging pollutant due to their potential environmental risks, but the distribution characteristics of particulate matters (PMs)-EPFRs from residential combustion source are poorly understood. In this study, biomass (corn straw, rice straw, pine and jujube wood) combustion was studied in lab-controlled experiments. More than 80% of PM-EPFRs were distributed in PMs with aerodynamic diameter (dae) ≤ 2.1 µm, and their concentration in fine PMs was about 10 times that in coarse PM (2.1 µm ≤ dae ≤ 10 µm). The detected EPFRs were carbon-centered free radicals adjacent to oxygen atoms or a mixture of oxygen- and carbon-centered radicals. The concentrations of EPFRs in coarse and fine PMs were positively correlated with char-EC, but the EPFRs in fine PMs exhibited a negative correlation with soot-EC (p < 0.05). The increase of PM-EPFRs signals with the increased dilution ratio during pine wood combustion was more significant than that from rice straw, which may be resulted from the interactions between the condensable volatiles and the transition metals. Our study provides useful information for better understanding the formation of combustion-derived PM-EPFRs, and will be instructive for its purposeful emissions control.

A Study of Bioenergy Production from Chilean Tessaria absinthioides

This study assesses whether the use of Tessaria absinthioides (TA) pellets as a bioenergy resource is feasible or not. Its fuel properties were characterized and its combustion behavior assessed via a traditional log wood stove with a basket of wood pellets. Combustion of pinewood (Pinus radiata) commercial pellets (CP) was used as a reference in order to analyze experimental results. TA has a high ash content of 8.1% and an HHV of 17.47 MJ kg−1. Alkaline index on the TA pellets was of 1.46 kg alkali GJ−1, a relatively high value, which resulted from high sodium content in ash. Oven and exhaust temperatures during the combustion of TA and CP present similar behavior. The combustion chamber’s highest temperature for CP was 841.15 °C, while for TA, the highest temperature was 685.65 °C. Furthermore, CO and PM emission was superior for TA pellets, averaging about 4943.6 ± 235.2 mg Nm−3 and 32.45 ± 6.49 mg MJ−1, respectively at 13% O2. Results obtained have shown that there were no apparent hindrances for an extensive use of TA as a bioenergy resource and use of pellet baskets to combust pellets in traditional wood log stoves.

Combustion Characteristics, Kinetics, and Thermodynamics of Pine Wood Through Thermogravimetric Analysis.

The thermal conversion of woody biomass is increasingly critical for the development of the energy processing technologies and fire safety engineering. The combustion characteristics, kinetics, and thermodynamics of pine wood were characterized through a thermogravimetric analyzer in the air atmosphere. There were two apparent peaks in the derivative TG curves for pine wood. The combustion process of pine wood was divided into two stages. Therein, the first stage occurring in the conversion degree range of 0-0.6 may be considered a one-step reaction. It was easier for pine wood to decompose under air than under nitrogen. Moreover, the first stage of pine wood combustion may be characterized by the diffusion model g(α) = [1 - (1 - α)1/3]2. The kinetic modeling showed a good agreement between the predicted and experimental conversion degree curves. In addition, the high comprehensive combustion index of pine wood at 10 K min-1 (6.73 × 10-7 %2 min-2 K-3) showed its great potential for bioenergy generation. Besides, both the value of ΔH and ΔS exhibited similar patterns with the activation energy value versus conversion degree, while the ΔG value almost remained at a positive constant with conversion degree. The average ΔH, ΔG, and ΔS value was nearly equal under different heating rates.

Analysis of the UV irradiation effect on the composition and absorption properties of carbon-containing particles according to measurements of smoke from combustion of pine wood in the Big Aerosol Chamber

Analysis of the UV irradiation effect on the composition and absorption properties of carbon-containing particles according to measurements of smoke from combustion of pine wood in the Big Aerosol Chamber

Temperature and emissivity measurements from combustion of pine wood, rice husk and fir wood using flame emission spectrum

Biomass combustion for heat and power generation is one of the best ways for substituting fossil fuels. It is necessary to develop in situ temperature and emissivity measurement technology for biomass volatile flame. In this study, combustion experiments on three biomass pellets of pine wood, rice husk and fir wood were carried out in a laboratory biomass burner at two A/F flowrates. A multi-wavelength radiation thermometry method was proposed to calculate temperature and wavelength-dependent emissivity based on Rayleigh approximation. The results showed that the temperature and emissivity of pine wood combustion were higher than those of rice husk and fir wood volatile flames. Though the emissivity of rice husk was less than that of fir wood, the temperature of rice husk combustion was higher than that of fir wood due to the latter's higher moisture content. The temperatures measured by the spectrometer system agreed well with the thermocouple data. The normalized emissivities of the three different biomass show the same trend, indicating the radiative properties of biomass volatile flames do not change with biomass species and combustion conditions.

An assessment of important SPECIATE profiles in the EPA emissions modeling platform and current data gaps

The United States (US) Environmental Protection Agency (EPA)'s SPECIATE database contains speciated particulate matter (PM) and volatile organic compound (VOC) emissions profiles. Emissions profiles from anthropogenic combustion, industry, wildfires, and agricultural sources among others are key inputs for creating chemically-resolved emissions inventories for air quality modeling. While the database and its use for air quality modeling are routinely updated and evaluated, this work sets out to systematically prioritize future improvements and communicate speciation data needs to the research community. We first identify the most prominent profiles (PM and VOC) used in the EPA's 2014 emissions modeling platform based on PM mass and VOC mass and reactivity. It is important to note that the on-road profiles were excluded from this analysis since speciation for these profiles is computed internally in the MOVES model. We then investigate these profiles further for quality and to determine whether they were being appropriately matched to source types while also considering regional variability of speciated pollutants. We then applied a quantitative needs assessment ranking system which rates the profile based on age, appropriateness (i.e. is the profile being used appropriately), prevalence in the EPA modeling platform and the quality of the reference. Our analysis shows that the highest ranked profiles (e.g. profile assignments with the highest priority for updates) include PM2.5 profiles for fires (prescribed, agricultural and wild) and VOC profiles for crude oil storage tanks and residential wood combustion of pine wood. Top ranked profiles may indicate either that there are problems with the currently available source testing or that current mappings of profiles to source categories within EPA's modeling platform need improvement. Through this process, we have identified 29 emissions source categories that would benefit from updated mapping. Many of these mapping mismatches are due to lack of emissions testing for appropriate source categories. In addition, we conclude that new source emissions testing would be especially beneficial for residential wood combustion, nonroad gasoline exhaust and nonroad diesel equipment.

Pyrolysis and Combustion Behavior of Pinewood After the Addition of Flame Retardants

Abstract To investigate the effects of flame retardants on pinewood combustion, a comprehensive analytical method has been devised based on a full description of the pyrolysis process. With the addition of ammonium polyphosphate (APP), ammonium dihydrogen phosphate (NH4H2PO4), and boric acid (H3BO3), the total amount of cellulose/hemicellulose decomposition products increased by 27.9, 63.1, and 14.2 %, respectively, and the yield of lignin-derived products decreased by 22.8, 57.7, and 13.2 %, respectively. Because of the easiest release of phosphoric acid, NH4H2PO4 had the most obvious impact on destruction of the char structure by volatiles released in the pyrolysis process, resulting in the highest peak heat release rate of 273.46 kW/m2 at a heat flux of 50 kW/m2. The addition of APP induced similar changes in the pyrolysis products, but it showed the best fire-resistance properties because of its lower surface temperature and less destruction of the char layer by volatiles. The effect of H3BO3 was weakest.

Examination of Combustion-Generated Smoke Particles from Biomass at Source: Relation to Atmospheric Light Absorption

ABSTRACTThe formation of carbonaceous aerosols from biomass combustion is associated with a high degree of uncertainty in global climate models. In this work, soot samples were generated from the combustion of pine wood, wheat straw and barley straw in a fixed bed stove; as well as from the combustion of biomass pyrolysis model compounds. Samples were collected on filters, which were used for the determination of Absorption Angstrom Exponent (AAE). In addition, the content and composition of elemental carbon (EC) and organic carbon (OC) were determined, and the interrelationships between these and the AAE were examined. It was found that the spectroscopic signature of samples with high ‘brown carbon’ emissions was comparable to that of many PAH and polyphenols, with AAE ranging from 1.0–1.2 for model compounds to 0.5–5.7 for biomass. In addition to the filter samples, particles were collected directly onto microscopy grids and analysed by transmission electron microscopy – electron energy loss spectroscopy (TEM-EELS) in order to determine structural characteristics. This was used to examine the impact of combustion conditions and flue gas dilution on particle structure. Smouldering phase and diluted particles were found to be less graphitic and twice as oxygenated as undiluted flaming phase particles. The results are interpreted to better understand the impact of combustion processes on soot formation from biomass combustion.Abbreviations: AAE: absorption angstrom exponent; ATN: light attenuation; AToFMS: aerosol time of flight mass spectrometer; BC: black carbon; BrC: brown carbon; C:O: carbon to oxygen ratio; CPD: cyclopentadienyl radical C5H5; DMS: differential mobility spectrometer; EC: elemental carbon; EELS: electron energy loss spectroscopy; HACA: hydrogen abstraction carbon addition; MCE: modified combustion efficiency; OA: organic aerosols; OC: organic carbon; PM: particulate matter; POM: primary (particulate)organic matter; Py-GC/MS: pyrolysis gas chromatography/mass spectrometry; sp2: amount of sp2 orbital hybridisation in atomic structure; SSA: single scattering albedo; TC: total carbon (BC+OC) or (EC+OC); TEM: transmission electron microscope; TGA: thermogravimetric analysis

Molecular characterization of primary humic-like substances in fine smoke particles by thermochemolysis–gas chromatography–mass spectrometry

In this study, the molecular structures of primary humic-like substances (HULIS) in fine smoke particles emitted from the combustion of biomass materials (including rice straw, corn straw, and pine branches) and coal, and atmospheric HULIS were determined by off-line tetramethylammonium hydroxide thermochemolysis coupled with gas chromatography and mass spectrometry (TMAH-GC/MS). A total of 89 pyrolysates were identified by the thermochemolysis of primary and atmospheric HULIS. The main groups were polysaccharide derivatives, N-containing compounds, lignin derivatives, aromatic acid methyl ester, aliphatic acid methyl ester, and diterpenoid derivatives. Both the type and distribution of pyrolysates among primary HULIS were comparable to those in atmospheric HULIS. This indicates that primary HULIS from combustion processes are important contributors to atmospheric HULIS. Some distinct differences were also observed. The aromatic compounds, including lignin derivatives and aromatic acid methyl ester, were the major pyrolysates (53.0%–84.9%) in all HULIS fractions, suggesting that primary HULIS significantly contributed aromatic structures to atmospheric HULIS. In addition, primary HULIS from biomass burning (BB) contained a relatively high abundance of lignin and polysaccharide derivatives, which is consistent with the large amounts of lignin and cellulose structures contained in biomass materials. Aliphatic acid methyl ester and benzyl methyl ether were prominent pyrolysates in atmospheric HULIS. Moreover, some molecular markers of specific sources were obtained from the thermochemolysis of primary and atmospheric HULIS. For example, polysaccharide derivatives, pyridine and pyrrole derivatives, and lignin derivatives can be used as tracers of fresh HULIS emitted from BB. Diterpenoid derivatives are important markers of HULIS from pine wood combustion sources. Finally, the differences in pyrolysate types and the distributions between primary and atmospheric HULIS suggested that the primary HULIS would undergo many atmospheric processes to reconstruct the macromolecular organic matter in atmospheric aerosols.

Some Aspects of the Mechanism of Formation of Smoke from the Combustion of Wood

This paper is concerned with an investigation of the formation of soot from the combustion of some of the primary pyrolysis products formed during pine wood combustion. Comparisons are made between the combustion products of model compounds, furfural for cellulose and eugenol and anisole to represent lignin (and n-decane for comparison) with the smoke emissions from the previously studied combustion of pine wood. These compounds were burned in a diffusion flame burner, and the appearance and composition of the resulting particulate and the adsorbed polynuclear aromatic hydrocarbon (PAH) precursors were studied by transmission electron microscopy (TEM), mass spectrometry and pyrolysis gas chromatography mass spectrometry (Py-GC-MS). The reactions leading to soot formation were modeled. It was concluded that wood soot formation proceeded via pyrolytic breakdown followed by a mechanism based on HACA (H-abstraction–C2H2-addition) reactions with the participation of cyclopentadienyl intermediates, while eugeno...

SO2 Release as a Consequence of Alternative Fuel Combustion in Cement Rotary Kiln Inlets

The combustion of alternative fuels in direct contact with the bed material of the rotary kiln may cause local reducing conditions and, subsequently, decomposition of sulfates from cement raw materials, increasing the SO2 concentration in the gas phase. The decomposition of sulfates increases the sulfur circulation and may be problematic because high sulfur circulation can cause sticky material buildup, affecting the process operation of the cement kiln system. The SO2 release from cement raw materials during combustion of pine wood and tire rubber has been studied experimentally in a high-temperature rotary drum, focusing on the influence of the fuel particle size and volatile content. The SO2 release increased with a decreasing fuel particle size and with an increasing fuel volatile content. Furthermore, CO, H2, and CH4, which are the main reducing gases released during fuel devolatilization, were introduced in different concentrations under the bed material. A threshold concentration for each reducing gas, below which no SO2 release occurs, was found. Introduction of the same molar amount of gas in different concentrations during different time periods showed that a higher reducing gas concentration during a short period (representing fuel devolatilization) released a higher total SO2 amount compared to a lower concentration during a long period (representing fuel char oxidation).

Source Apportionment and Distribution of Polycyclic Aromatic Hydrocarbons, Risk Considerations, and Management Implications for Urban Stormwater Pond Sediments in Minnesota, USA

High concentrations of polycyclic aromatic hydrocarbons (PAHs) are accumulating in many urban stormwater ponds in Minnesota, resulting in either expensive disposal of the excavated sediment or deferred maintenance by economically challenged municipalities. Fifteen stormwater ponds in the Minneapolis-St. Paul, MN, metropolitan area were studied to determine sources of PAHs to bed sediments through the application of several environmental forensic techniques, including a contaminant mass balance receptor model. The model results were quite robust and indicated that coal tar-based sealant (CT-sealant) particulate washoff and dust sources were the most important sources of PAHs (67.1%), followed by vehicle-related sources (29.5%), and pine wood combustion particles (3.4%). The distribution of 34 parent and alkylated PAHs was also evaluated regarding ancillary measurements of black carbon, total organic carbon, and particle size classes. None of these parameters were significantly different based on major land-use classifications (i.e., residential, commercial, and industrial) for pond watersheds. PAH contamination in three stormwater ponds was high enough to present a risk to benthic invertebrates, whereas nine ponds exceeded human health risk-based benchmarks that would prompt more expensive disposal of dredged sediment. The State of Minnesota has been addressing the broader issue of PAH-contaminated stormwater ponds by encouraging local municipalities to ban CT-sealants (29 in all) and to promote pollution prevention alternatives to businesses and homeowners, such as switching to asphalt-based sealants. A statewide CT-sealant ban was recently enacted. Other local and regional jurisdictions may benefit from using Minnesota's approach where CT-sealants are still used.

In Situ Study of Soot from the Combustion of a Biomass Pyrolysis Intermediate—Eugenol—and n-Decane Using Aerosol Time of Flight Mass Spectrometry

This paper is the first work where a typical atmospheric aerosol tool such as an Aerosol Time Of Flight Mass Spectrometer (ATOFMS) has been applied to study the mechanism of soot formation. In particular, it considers the formation of soot from one of the major components released during the initial stages of biomass combustion, namely, eugenol, and n-decane, a compound chosen as representative of liquid hydrocarbon fuels. The analytical method has been optimized to be able to obtain reproducible mass spectra (MS) in minutes that allow the determination of elemental carbon/total carbon (EC/TC) ratios and qualitative determination of the organic composition of the analyzed soots. The compositions of the soots produced in the combustion of eugenol and n-decane are compared and the results from this study are compared with those obtained by offline techniques and interpreted in mechanistic terms confirming the key role of lignin in soot formation from pine wood combustion. The results have implications for h...

Mechanistic Aspects of Soot Formation from the Combustion of Pine Wood

Carbonaceous soot has been generated from pine in a range of appliances to simulate different combustion conditions. The fuel as well as biomass cell wall components have been studied by pyrolysis-GC−MS and pyrolysis-GC−TCD. In addition, the soots have been probed using both pyrolysis-GC−MS and direct inlet mass spectrometry (DI−MS). The material collected from the pine combustion is smoke, and the major component is a carbonaceous soot. The soots contain both organic carbon (adsorbed species) and black (solid) soot, and the organic carbon consists of primary pyrolysis products from the cell wall components, as well as decomposition products, PAH and oxidized PAH. The black carbon contains oxygen functionality (of the order of 5−10 wt % O), and there are indications that this is incorporated during soot growth, although surface oxidation on reactive sites could also be important. The decomposition products suggest an important additional PAH route is via cyclopentadiene, which is derived after cracking of lignin monomer fragments. Kinetic modeling also highlights the lignin monomers as important contributions to the soot production pathways. A model is proposed which, in addition to the hydrogen abstraction carbon addition (HACA) mechanism, incorporates the cyclopentadiene and the O-PAH addition routes to soot.

Filtration Combustion of Humid Fuels

A comparative study of the filtration combustion of two types of fuel in mixtures with an inert material at various degrees of humidity was performed. The fuels were activated birch charcoal and pinewood. It was demonstrated that the combustion of activated charcoal was only slightly affected by humidity. In the case of pinewood combustion, an increase in the fuel humidity caused substantial decreases in the gasification mass rate and temperature. The composition of the gaseous products was found to change only for mixtures containing a large amount of pinewood with a humidity of more than 35%. This can be accounted for by a change in the extent of pinewood pyrolysis.

Emission of Oxygenated Species from the Combustion of Pine Wood and its Relation to Soot Formation

Combustion tests of pine wood cribs have been performed in different airflows in a fire test chamber. VOC in the flue gas has been monitored on-line using FTIR. Soot was collected at different heights above the bed on to quartz fibre filters and was characterized using pyrolysis-GC-MS. Correlation between combustion conditions and emission profiles were elucidated. The soot contained significant amounts of adsorbed oxygenated material derived from pyrolysis of the wood. Three types of material were identified: pyrolysis products, pyrolysis recombination products and PAH, and significant proportions of O-PAH are also present. Oxygenated PAH increased with temperature and higher air flow rate whereas oxygenated phenolic type material increased with lower temperature and lower air flow rate. Cooler flames from oxygen-starved fires akin to conditions in household fires produce significant higher proportions of phenolic material.Oxygen appears to play a significant role in the production of soot and there appear to be two routes by which PAH material can be synthesized. Firstly through conventional hydrocarbon mechanisms such as the HACA method and secondly through a route involving the polymerization of biomass pyrolysis fragments. A number of important species are identified which could be intermediates between these pyrolysis products and PAH.

Gas Chromatographic Analysis of Organic Marker Compounds in Fine Particulate Matter Using Solid-Phase Microextraction

A gas chromatographic method that uses solid-phase microextraction for analysis of organic marker compounds in fine particulate matter (PM2.5) is reported. The target marker compounds were selected for specificity toward emission from wood smoke, diesel or gasoline combustion, or meat cooking. Temperature-programmed volatilization analysis was used to characterize the thermal stabilities and volatile properties of the compounds of interest. The compounds were thermally evaporated from a quartz filter, sorbed to a solid phase microextraction (SPME) fiber, and thermally desorbed at 280 °C in a gas chromatograph injection port connected via a DB 1701 capillary separating column. Various experimental parameters (fiber type, time, and temperature of sorption) were optimized. It was found that high extraction yield could be achieved using a polyacrylate fiber for polar substances, such as levoglucosan, and a 7-µm polydimethylsiloxane (PDMS)-coated fiber for nonpolar compounds, such as hopanes and polyaromatic hydrocarbon. A compromise was made by selecting a carboxen/PDMS fiber, which can simultaneously extract all of the analytes of interest with moderate-to-high efficiency at 180 °C within a 30-min accumulation period. The optimized method was applied to the determination of levoglucosan in pine wood combustion emissions. The simplicity, rapidity, and selectivity of sample collection with a polymer-coated SPME coupled to capillary gas chromatography (GC) made this method potentially useful for atmospheric chemistry studies.

06/01247 Fuel size effect on pinewood combustion in a packed bed: Yang, Y. B. et al. Fuel, 2005, 84, (16), 2026–2038

06/01247 Fuel size effect on pinewood combustion in a packed bed: Yang, Y. B. et al. Fuel, 2005, 84, (16), 2026–2038

Fuel size effect on pinewood combustion in a packed bed

In this paper, particle size effect on pinewood combustion in a stationary packed bed was investigated. Mass loss rate, temperature profile at different bed locations and gas compositions in the out-of-bed flue gases were measured at a fixed primary air flow rate. Pinewood cubes was fired with size ranging from 5 to 35 mm. A unique numerical model applicable to thermally thick particles was proposed and relevant equations were solved to simulate the non-homogeneous characteristics of the burning process. It is found that at the operating conditions of the current study, smaller particles are quicker to ignite than larger particles and have distinctive combustion stages; burning rate is also higher with smaller fuel size; and smaller fuels have a thinner reaction zone and result in both higher CO and CH 4 concentrations in the out-of-bed flue gases; on the other hand, larger particles produced a higher flame temperature and result in higher H 2 concentration in the flue gases. Larger particles also cause the combustion process becoming more transient where the burning rate varies for most part of the combustion process.

Assessment of the Estrogenic Activity of Flue Gases from Burning Processes by Means of the Yeast Based Human Estrogen Receptor (hER) Bioassay

Combustion processes are known to produce organic micro-pollutants in the flue gas at concentrations ranging over several orders of magnitude. Some organic micro-pollutants are suspected of being pseudo-estrogens and as such they can affect the public health. In this study, the possible application of the yeast based human estrogen receptor (hER) bioassay to screen flue gas streams for the presence of estrogenic active micro-pollutants was explored. Specifically, the protocol was modified to allow the detection and quantification of the potential estrogenic active non-polar organic micro-pollutants contained in the flue gas matrix. The modified assay was calibrated using a model estrogenic compound (17-α-ethinylestradiol (EE2)) dissolved in methylene chloride at concentrations ranging from 3 ng l−1 to 3000 ng l−1. The effective concentration to elucidate a 50% response (EC50) was 87 ngl−1 of EE2 equivalent dissolved in methylene chloride. Samples of methylene chloride used to trap non-polar micro-pollutants in flue gas from combustion of pine wood were found to clearly register estrogenic activity by the bioassay under certain conditions. The combustion tests were performed with pinewood alone and with pine wood in the presence of both Copper-naphthenate and copper(II)chloride at 600°C and 1000°C. These conditions must be considered as experimental rather than practical. Overall, the results suggest that, by means of this modified assay, it is possible and warranted to screen systematically for estrogens in flue gas combustion processes.