Search

Levoglucosan is used as a tracer of biomass burning; however, its determination often requires expensive analytical techniques. Therefore, this study describes the development of an inexpensive and useful method using paper-based analytical devices (PADs) to determine levoglucosan based on colorimetric measurements. The color intensities were correlated with the analytical concentrations and presented linear behavior in the range from 0 to 64.8 μg mL−1. The achieved limits of detection and quantification were 2 and 6 μg mL−1, respectively. The conversion rate of levoglucosan into glucose was 81 ± 8% and the average recovery was 105 ± 9%. Moreover, the method presented selectivity for levoglucosan, showing variation in colorimetric signal intensity lower than 8% in the presence of other saccharides (xylose, glucose, galactose, maltose, mannose, arabinose, and fructose). The accuracy of the method was confirmed by comparison with gas chromatography-mass spectrometry. The proposed method was explored to determine levoglucosan in samples of atmospheric particulate matter collected in Goiania city (Brazil) and the values ranged from 0.08 to 1.10 μg m−3, showing the high impact of the biomass burning to the particulate matter in the region's atmosphere. The method was also used to detect levoglucosan in rainwater samples. Therefore, the use of PADs can simplify fieldwork involving the determination of levoglucosan in atmospheric particulate matter. Image 1 • Paper-based analytical devices were used to determine levoglucosan. • The method is inexpensive, useful and presented selectivity for levoglucosan. • The highest levoglucosan concentration was determined in the dry season. • The particulate matter chemical composition was highly affected by biomass burning. [ABSTRACT FROM AUTHOR]

The combustion of biomass and waste paper sludge in a fluidized bed is ecologically profitable. However, a large amount of by-product with high hydraulic reactivity is produced and is considered as wastes. Most of the time the waste paper fly ash (WPFA) goes to landfills, therefore new utilization methods are necessary. In some countries, the high content of metallic and metalloids trace elements (MMTE) in WPFA, more specifically Barium (Ba) and Lead (Pb) makes its valorization difficult. In this paper, the Lightweight Aggregates (LWA) was produced from WPFA by granulating with water in high-intensity granulator. Since WPFA is rich in CaO, the addition of water promotes rapid setting and hydration compared to other types of ash. In this study, different granulation parameters were investigated, such as the rotation modes between the steel pan and the impeller, the rotation speed of the steel pan, the granulation time, in order to improve the mass percentage of the targeted LWA (2–16 mm). In order to evolve the immobilization potential of Ba and Pb, a carbonation process was performed, exposing the manufactured LWA to pure carbon dioxide (CO 2) gas at laboratory scale. The physical, morphological, thermal and mechanical characterizations were performed on LWA for use in mortars, concretes or civil engineering constructions. Results have demonstrated the influence of the rotation mode between the steel pan and the on the distribution of WPFA inside the steel pan and the change in the growth rate of the granules can be observed. Increased density and improved compressive strength with low porosity and water absorption were also found in LWA after carbonation. This was due to the occurrence of both a carbonation reaction and a hydration reaction. Furthermore, the results of thermogravimetry and SEM-EDS confirmed the formation of hydrated phases (ettringite, carboaluminates), also the formation of calcite in the pores and the external surface of the LWA. Regarding environmental aspects, the results have revealed that Ba and Pb were well immobilized in the solid matrix after carbonation. [Display omitted] • LWA was manufactured from WPA without any agglomerating agents. • The physical-chemical properties of LWA were improved after carbonation. • The resulted LWA meet the requirements of NF EN -13,055-1. • The microstructure of LWA was studied before and after carbonation. • Influence of time, mode and rotation speed on the size of the manufactured LWA. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of wildfire is crucial for developing management and intervention strategies. Mathematical and computational models can be used to improve our understanding of wildfire processes and dynamics. This paper presents a systematic study of a widely used advection–diffusion–reaction wildfire model with non-linear coupling. The importance of single mechanisms is discovered by analysing hierarchical sub-models. Numerical simulations provide further insight into the dynamics. As a result, the influence of wind and model parameters such as the bulk density or the heating value on the wildfire propagation speed and the remaining biomass after the burn are assessed. Linearisation techniques for a reduced model provide surprisingly good estimates for the propagation speed in the full model. • The hierarchy of the mechanisms of an advection-diffusion-reaction wildfire model is examined analytically and numerically. • In the model, decreasing the initial biomass reduces wildfire propagation speed, with minimal effect on final biomass. • Linearisation techniques provide good approximations of the wildfire propagation speed. • The spatially lumped model provides a good prediction of the terminal biomass. [ABSTRACT FROM AUTHOR]

Rural fires are currently one of the main global disasters, and Portugal is among the countries that have suffered from them for decades. These fires pose economic, environmental, and social threats to the country. A primary cause of rural fires is the burning of biomass to clear agroforestry residues. Thus, combating rural fires requires more effective forest management, particularly the removal of forest residues that serve as fuel. These residues, also known as biomass, have significant potential for energy production and biofuel use. This paper proposes a model that integrates the PROMETHEE decision-making method with the roadmapping. This proposed model includes 7 steps, including the planning of the roadmap, the definition of the decision problem, gathering information and building the roadmap. The proposed model was applied to develop a roadmap proposal for the recovery of surplus agroforestry biomass in Portugal, identifying the most emerging conversion technologies in the national context. With the roadmap developed, it was possible to understand that the recovery of surplus agroforestry biomass in Portugal involves several sectors. The energy sector is one of those that can benefit from the recovery of leftover agroforestry biomass, both from the point of view of carbon neutrality and energy independence. Forestry management is another of the great advantages of recovering leftover forestry biomass and, consequently, reducing the number of fires. In the context of recovery, combustion is the most widely used technology for producing energy or heat. The technology identified as most emerging in the upcoming years is gasification. Investment in scientific research is essential for the success of this sector, as is the development of public incentive policies and more engagement from all stakeholders. This paper conclude that valorizing agroforestry residues can reduce rural fire risks while promoting energy independence, sustainable regional development, and innovation in Portugal. • The paper proposes an integrated PROMETHEE II-Roadmap model. • The proposed model is applied to the valorization of residual agroforestry biomass in Portugal (RAFB). • Benefits of RAFB valorization include reduction of rural fires, increased renewable energy alternatives, and sustainable regional development. • An evaluation of biomass conversion technologies is performed, and gasification is identified as the most emerging. • The paper emphasizes the need in the sector for research investment, stakeholder engagement and development of supply chains. [ABSTRACT FROM AUTHOR]

Exact and trusty prediction of pollutant emissions is pivotal for optimal combustion control in biomass cogeneration systems, which possess multiple variables, high-volume data streams, and dynamic characteristics. Aiming at the multivariate dynamic systems, this paper extends a classical fast relevance vector regression (FRVR) algorithm into a multivariate form to accomplish synchronous multi-pollutant prediction. Meanwhile, a flexible and effective online training strategy is proposed to solve the problems of low accuracy of multi-step prediction and lack of dynamic updating capability. First, the given dataset is divided utilizing the k -means clustering method to enhance the clustering of similar features and expedite the prediction process. Then, the classical FRVR algorithm is extended into a multiple-output form, enabling the simultaneous prediction of multiple pollutant emissions. Moreover, the incremental learning method is introduced into the proposed multivariate FRVR model to improve its dynamic performance and online learning ability. Finally, the proposed method's effectiveness is verified through a biomass cogeneration systems case. Experimental findings fully illustrate that the proposed method provides the lower RMSE and MAE while runtime decreases by 50% and R 2 reaches 96%. The proposed method significantly outperforms others, showing excellent potential in the pollutant prediction field. • An IMFRVR algorithm is proposed to predict multiple pollutant concentrations. • The k -means method cluster the data to extract useful information from the original data. • The MFRVR model is built by setting a Gaussian distribution to the FRVR weight matrix. • The incremental learning algorithm is employed to update prediction model dynamically. [ABSTRACT FROM AUTHOR]

The interaction between volatile and char is widespread in combustion. The effect of this interaction on the conversion of fuel-N to NO x is significant, but the mechanism remains to be comprehensively unveiled. Thus, in this paper, the NO and N 2 O conversion of nitrogen-containing biomass models (glutamate, glycine, phenylalanine) during combustion at high temperatures (800–1500 °C) is investigated using two combustion modes, separated combustion (in which volatile and char are burned separately) and coupled combustion (in which volatile and char are burned simultaneously), in an O 2 /Ar atmosphere. A new pathway for N 2 O formation resulting from the interaction between volatile and char is identified. At low temperatures, this interaction facilitates the conversion of fuel-N to N 2 O. For instance, during the separated combustion of glutamate at 800 °C, the conversion rates of fuel-N to N 2 O and NO are 26.3 % and 20.4 %, respectively. However, in coupled combustion, these conversion rates shift to 48.1 % for N 2 O and 3.6 % for NO. At high temperatures, this interaction promotes the conversion of fuel-N to NO. For instance, during the separated combustion and coupled combustion of glutamate at 1500 °C, the conversion rates of fuel-N to NO are 6.2 % and 16.6 %, respectively. Similar patterns are observed for the other two amino acids. In both combustion modes, the co-firing of cellulose, lignin, and hemicellulose with glutamic acid significantly suppresses the production of N 2 O. The conversion rate of N 2 O decreases by about 7 %–10 %, while the impact on NO release shows either a suppressive or promotive effect in different temperature intervals. These results play a crucial role in the development of efficient and clean combustion technology for biomass. [Display omitted] • A novel N 2 O formation pathway from volatile-char interaction has been identified. • Volatile-char interaction enhances NO formation at 1300–1500 °C. • Accurate volatile-NO/N 2 O and char-NO/N 2 O contributions were determined. • Co-firing with cellulose, lignin, and hemicellulose inhibits the formation of N 2 O. [ABSTRACT FROM AUTHOR]

South Asian air pollutants exert substantial effect on the climate and environment change over the Tibetan Plateau (TP). This paper investigates the trans-boundary transport of PM 10 , PM 2.5 , and O 3 from South Asia to the TP via WRF-Chem sensitive analysis. It is found that PM 10 , PM 2.5 , and O 3 over South Asia are mainly sourced from anthropogenic sources. South Asian emissions contribute up to 54% of PM 10 (PM 2.5) in the TP in the pre-monsoon season. For O 3 , the highest contribution of 18.13% is in the monsoon season, while the lowest contribution of 8.67% is in the winter season. To evaluate the respective contributions of anthropogenic and biomass burning emissions in South Asia to PM 10 , PM 2.5 , and O 3 in the TP, anthropogenic and biomass burning emissions in South Asia are considered separately. The results show that the largest percentage contribution of PM 10 (PM 2.5) from South Asian anthropogenic emissions to PM 10 (PM 2.5) in the TP with value of 35.86% (37.77%) occurs in winter, while the lowest percentage contribution of 16.52% (16.77%) appears in the monsoon season. For O 3 , the largest contribution of 17.74% from South Asian anthropogenic emissions appears in the monsoon season, whereas the lowest contribution of 8.59% occurs in winter. Compared to the anthropogenic emissions, the biomass burning emissions in South Asia have a relative less contribution to PM 10 , PM 2.5 , and O 3 in the TP. The largest contribution of PM 10 (PM 2.5) from South Asian biomass burning emissions to PM 10 (PM 2.5) in the TP is 20.04% (18.37%) in the pre-monsoon season. Conversely, the lowest contribution of 0.58% (0.53) appears in the monsoon season. O 3 from South Asian biomass burning emissions contributes <1% to O 3 in the TP in each season, implying that the biomass burning emissions in South Asia have little effect on O 3 in the TP. This study is of great significance to the ecological environment protection for the TP. • Contributions of South Asian emissions to PM 10 , PM 2.5 , and O 3 in the TP are quantified. • Anthropogenic emissions in South Asia have a larger contribution to PM 10 , PM 2.5 , and O 3 in the TP. • O 3 from South Asian biomass burning emissions contributes <1% to O 3 in the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

In this paper, we applied the Dispersion Normalised Positive Matrix Factorisation (DN-PMF) approach recently proposed in the literature to provide a more realistic picture of the relative importance of emission strength vs. atmospheric dispersion conditions. The disentanglement of such effects is of great concern in pollution hot spots like the Po Valley (Italy), where particulate matter limit values are exceeded despite the existing abatement measures. To explore the potentiality of the DN-PMF approach – still scarcely applied in the literature – a well-chemically characterised PM 1 (atmospheric particles with aerodynamic diameter <1 μm) dataset comprising samples collected at different time resolutions at an urban background site (Bologna) in the southern Po Valley was used. Indeed, it is well known that shallow mixing layers promote pollutant accumulation but this observation is not enough to exclude an enhancement of emission strength which could be tackled by appropriate abatement strategies. The source apportionment of sub-micron sized aerosols having a quite long atmospheric residence time in a complex environment like the Po Valley - which is also strongly impacted by secondary aerosol formation on a basin-scale - is generally quite challenging when using receptor models. Due to the availability of a huge dataset with variables having multiple time resolutions, in this work the DN-PMF was implemented in a multi-time resolution approach (MT) to achieve a better source identification and to gain knowledge about the relative importance of atmospheric dilution vs. emissions. A comparison between results obtained by the application of the regular multi time resolution (REG-MT) vs. the DN-MT approach is presented here for the five factors identified (nitrate-dominated, sulphate-dominated, biomass burning, mineral dust, and urban aerosol). The first interesting outcome is that REG-MT and DN-MT results do not point at significant differences in temporal patterns for aerosol components and sources impacting at the basin-scale (i.e. sulphate- and nitrate-dominated aerosol, biomass burning) thus suggesting that the diel modulation of these PM 1 emissions is somehow masked by the stronger variability of the mixing layer. Conversely, contributions from local sources with more pronounced diel variation like traffic are quite well reproduced by DN-MT and the ambient concentrations are enhanced compared to REG-MT. This is an important piece of information highlighting that PM 1 concentrations from local sources have been likely underestimated by REG-MT assessments. To our knowledge, this is one of the very few applications of DN-MT and the first one at a European site where the huge effort made to implement air pollution containment measures is still not very much effective in reducing PM levels; moreover, in this paper a detailed discussion about the possible interpretation of the output of DN-MT in terms of temporal patterns is reported. [Display omitted] • High PM levels are due to atmospheric stability and emission strength; DN-PMF points out the source emission role. • Secondary aerosol-dominated factors showed a regional nature. • Urban aerosol factor was highly enhanced by dispersion-normalisation. [ABSTRACT FROM AUTHOR]

Cheap Production of bioethanol from renewable lignocellulosic waste has the imperative potential to economically cut burgeoning world dependency on fossils while reducing net emission of carbon dioxide (CO 2), a principal greenhouse gas (GHGs). This paper highlights key benefits and status of bioethanol production technologies, aiming mainly on recent developments and its key potentials in Pakistan. Most sector of Pakistan economy heavily rely on the energy and power that is being produced using traditional approaches like from oil and hydel. However, the sedimentation in dams cut-down the energy generation and overwhelmed severe energy crisis that are witnessed since last decade. Thus, Pakistan must go to avail alternative sources of energy like hydro, biomass and solar so that energy security can be ensured to recover the tremendous loss of economy. Renewable biomass is abundantly available in Pakistan which can be used to produce bioethanol and electricity. Currently, 22 distilleries are producing the ethanol from sugar cane bagasse and out of these only 8 distillation units are producing motor fuel grade ethanol. The current bioethanol production of country is about 403,500 tons/year along with 2423 tons of biodegradable waste available in major cities. In addition, Pakistan produces 6.57, 0.5, 0.66, and 2.66 million tons of sugarcane, corn, rice, and wheat straw per annum, respectively. This biomass can produce 1.6 million liters of bioethanol which can produce approximately 38% of Pakistan's electricity annually. Despite having large potential, Pakistan is still producing a few volumes of ethanol from sugarcane bagasse. The production of bioethanol can be boosted using (I) pretreatment of agricultural biomass by alkali (II) enzymatic and bacteria-based hydrolysis of the biomass (III) post-hydrolysis using pressurized steam above 100 °C (IV) Fermentation of the biomass@ 7–10 h and (V) and (VI) distillation of bioethanol. This study recommends (1) increase R&D capacities mainly in the west and central regions of Pakistan, (2) initiate mega-projects to promote integrated bio-ethanol production at agriculture farms by providing 1/3 subsides, (3) purchase of bioethanol directly from the major agricultural farms, (4) produce bioethanol related manpower from the key research institutes as specified in this study. • Upgradation of inefficient biogas to bioethanol can solve energy crisis. • Study witnessed huge potential of bioethanol (403,500 tons/year) from cheap biomass. • Key technical barriers in the green development of ethanol is emphasized fact-sheet. • Study implementation will replace inefficient biomass burn into ethanol combustion. • Study will definitively help policy makers to sustain lives of Pakistan people. [ABSTRACT FROM AUTHOR]

PM emission is one of key issues in the biomass combustion of heat and power plants. In this paper, rice husk (RH) was co-combusted with cotton stalk (CSK) or cornstalk (CS) to study the PM emission behaviors. The experimental results show that the addition decreases PM 1 yields by 20.13–54.65% for CSK and 45.99–76.70% for CS in comparison to the CSK or CS combustion alone. A strong synergistic effect exists during the co-combustion process, which can appreciably inhibit the generation of fine particulate matter. The synergistic effect is caused by the physical dilution effect, and mainly by the reaction between alkali metals species in cornstalk/cotton stalk ash and Si-containing species in rice husk ash to inhibit the volatilization of alkali metals. However, the PM reduction degree is also affected by the ash chemistry, especially the Si/(Ca + Mg) ratio, as confirmed by the higher synergistic effect of rice husk/cornstalk compared to rice husk/cotton stalk. The results suggest that co-combustion of biomass with high Si-containing rice husk is a promising approach to reduce PM 1 emissions during biomass co-combustion. [ABSTRACT FROM AUTHOR]

• A CFD biomass ignition delay model is developed. • The model is able to accurately distinguish between different biomass fuels. • The model reasonably predicts the effect of particle size on ignition. • The OH species was found to better reproduce ignition results at lower temperatures. • The CH species was found to better reproduce ignition results at higher temperatures. This paper utilizes a CFD approach to study the ignition of pulverized biomass particles. Ignition is a critical parameter in a reactor's design and process efficiency, and a reliable and relatively quick method of its determination is a necessity. CFD is a well-established tool that has already proved credible in many combustion/gasification applications, and for that reason, its application in ignition-related studies should be paramount. In this research, an Eulerian-Lagrangian approach is used where key stages during biomass combustion such as inert heating, evaporation, devolatilization, gas-phase kinetics, char conversion, particle transport, and radiative transport are considered. The predictions of the model are verified against experimentally measured ignition data from the literature and are found to be in good agreement. The ignition delay is determined by monitoring the concentrations of OH (hydroxyl) and CH (methyl) radicals. It is concluded that using OH species as ignition indicator allowed reproducing the delay better for lower temperatures, whereas, for temperatures above 1600 K, CH species was found to be more accurate. The CFD approach was eventually found reasonable and relatively fast in ignition delay predictions enabling its wider use in industrial applications. [ABSTRACT FROM AUTHOR]

The production of biofuels to be used as bioenergy under combustion processes generates some gaseous emissions (CO, CO 2 , NO x , SO x , and other pollutants), affecting living organisms and requiring careful assessments. However, obtaining such information experimentally for data evaluation is costly and time-consuming and its in situ obtaining for regional biomasses (e.g. , those from Northeast Brazil (NEB) is still a major challenge. This paper reports on the application of artificial neural networks (ANNs) for the prediction of the main air pollutants (CO, CO 2 , NO, and SO 2) produced during the direct biomass combustion (N 2 /O 2 :80/20%) with the use of ultimate analysis (carbon, hydrogen, nitrogen, sulfur, and oxygen). 116 worldwide biomasses were used as input data, which is a relevant alternative to overcome the lack of experimental resources in NEB and obtain such information. Cross-validation was conducted with k-fold to optimize the ANNs and performance was analyzed with the use of statistical errors for accuracy assessments. The results showed an acceptable statistical performance for all architectures of ANNs, with 0.001–12.41% MAPE, 0.001–5.82 mg Nm−3 MAE, and 0.03–52.30 mg Nm−3 RMSE, highlighting the high precision of the emissions studied. On average, the differences between predicted and real values for CO, CO 2 , NO, and SO 2 emissions from NEB biomasses were approximately 0.01%, 10−6%, 0.14%, and 0.05%, respectively. Pearson coefficient provided consistent results of concentration of the ultimate analysis in relation to the emissions studied and effectiveness of the test set in the developed models. [Display omitted] • Assembly of a worldwide database with different lingocellulosic biomasses. • Prediction of main air pollutants (CO, CO 2 , NO, and SO 2) for the selected samples. • Information obtained on Brazilian biomasses without the need for many experiments. • Use of different evaluation metrics to validate the established models. • The ANN's showed differences between predicted and estimated values below 1.0%. [ABSTRACT FROM AUTHOR]

Summer 2019 is remembered as one of the most intense biomass burning (BB) seasons on record for the Northern Hemisphere. During the MOSAiC expedition, a smoke-dominated layer was identified in the upper troposphere over the North Pole region. The origin of this layer remains unclear, and no evidence has been found to indicate the intrusion of such particles into the Arctic Boundary Layer. The main aim of this work was to evaluate if biomass burning events in the summer 2019 were detectable at Gruvebadet Atmospheric Laboratory, close to Ny-Å lesund (Svalbard Islands) during the second half of 2019. This paper proposes an innovative approach to discriminate biomass burning events based on optical measurements combined with chemical analysis and air mass back-trajectories. Monthly background values of optical coefficients were defined using multi-annual (2018–2021) statistics and twelve possible events were identified. Source apportionment through positive matrix factorization (PMF) identified that the biomass burning factor by PMF accounted for only 2% of the total investigated concentration. The specific biomass burning tracers such as levoglucosan and phenolic compounds were compared with optical measurements and with the PMF results. Air mass trajectory analysis revealed that the early summer fires detected at Ny-Å lesund originated mainly from North America, as also confirmed by the presence of BB factor of PMF, levoglucosan and also vanillic species (softwood combustion tracers). In contrast, the chemical composition and air masses analysis of the highest peak detected in early December suggested residential heating as plausible source, further amplified by the onset of the harsh winter season and the expansion of the polar vortex towards mid-latitudes. • 12 mild pollution events have been identified investigating optical properties. • Biomass burning's contribution accounted for 2% of the total concentration. • Most of the events were detected during the fall. • The latest events in December may have been impacted by emissions from home heating. [ABSTRACT FROM AUTHOR]

The interactions among chlorine (Cl), sulfur (S), and alkaline and alkaline-earth metals (AAEMs) are the critical factors that affect the formation, transformation, and deposition of ash during biomass and coal gasification and combustion. These issues cause slagging, agglomeration, corrosion, and other problems related to the safety performance of gasifiers and boilers. A better understanding of the determination methods, modes of occurrence, migration routes, and control technologies of Cl and S is the basis for clean and efficient utilization of biomass and coal. The paper summarizes the research work in this field, namely: (1) The modes of Cl and S occurrence in biomass and coal are introduced, mainly in different forms of inorganic and organic Cl/S compounds; (2) The principles, merits and demerits of quantitative determination methods for Cl and S are sorted out and compared; (3) The migration routes of Cl and S, mainly related to their modes of occurrence, reaction evolution, temperature, and atmosphere; and (4) The interactions among Cl, S, and AAEMs and its induced issues, especially the challenging problems related to ash, including alkali-induced slagging, silicate melt-induced slagging (ash fusion), agglomeration, and corrosion. Finally, ecological and technological significance of the Cl and S release is discussed. This knowledge is of great significance to effectively control the emission of Cl and S pollutants, stable operation of gasifiers and boilers, cleaner and more efficient utilization of coal, as well as to diminish the consumption of fossil energy and heighten the availability of renewable energy in such thermochemical conversion processes. • Migration routes of chlorine and sulfur are elucidated. • Interactions among chlorine, sulfur, and AAEMs are summarized. • Ecological and technical significance of chlorine and sulfur release is discussed. [ABSTRACT FROM AUTHOR]

With continuous expansion of the heat produced from biomass energy, the problems of biomass ash melting and slagging have become increasingly prominent. Studies of mineral transformations and melting behaviour in biomass ash are helpful for understanding the slagging process fully. In this paper, ash samples prepared from corn straw, sawdust and rice husk were studied with an ash melting point analyser, simultaneous thermal analyser, XRD and SEM‒EDS. The results showed that the deformation temperature (DT) of corn straw was the lowest, while that of rice husk was the highest. The variations in ash weight loss and temperatures indicated that the two main paths for ash loss were decomposition and volatilization. With increasing combustion temperature, eutectic salts with low melting points were formed in the ash, such as potassium silicate and calcium silicate, and the liquid phase and crystalline phase coexisted at 1000 °C. In this paper, the influence of different elements on the ash structure and the changes occurring in ash structure during combustion and ash melting point tests are explained by considering the silicate network structure. The ash melting behaviour observed during biomass combustion is clarified, which provides a theoretical basis for preventing biomass ash from melting and slagging. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] Biomass is considered to be one of the most easily available and high-potential renewable power sources. Pyrolysis and combustion are the most common ways of utilizing biomass. A complex multiple-criteria analysis to identify the most promising technology of using various types of biomass has never been previously performed. The study is focused on comparing two typical techniques of utilizing agricultural and forestry biomass for bioenergy and valorization. In this paper, the direct combustion and pyrolysis of biomass were experimentally studied. The environmental and energy performance parameter of the investigated processes were determined for separate biomass components (leaves, straw, sawdust) and a group of mixtures from them. It was established that the biomass mixtures combustion has better environmental characteristics. Thus, the main anthropogenic emissions decreased by 8–66%. In addition to that, the pyrolysis of a biomass mixture from a group of components has a 30% higher yield of combustible gases. The analysis of relative efficiency indicators of two processes where biomass was used as an energy resource showed that a biomass-derived composite fuel is more efficient than its individual components. [ABSTRACT FROM AUTHOR]

Abstract: Caledonian Paper (CaPa) is a major paper mill, located in Ayr, Scotland. For its steam supply, it previously relied on the use of a Circulating Fluidized Bed Combustor (CFBC) of 58 MWth, burning coal, wood bark and wastewater treatment sludge. It currently uses a bubbling fluidized bed combustor (BFBC) of 102 MWth to generate steam at 99 bar, superheated to 465 °C. The boiler is followed by steam turbines and a 15 kg/s steam circuit into the mill. Whereas previously coal, wood bark and wastewater treatment sludge were used as fuel, currently only plantation wood (mainly spruce), demolition wood, wood bark and sludge are used. Since these biosolids contain nitrogen, fuel NO x is formed at the combustion temperature of 850–900 °C. NO x emissions (NO + NO2) vary on average between 300 and 600 mg/Nm3 (dry gas). The current emission standard is 350 mg/Nm3 but will be reduced in the future to a maximum of 233 mg/Nm3 for stand-alone biomass combustors of capacity between 50 and 300 MWth according to the EU LCP standards. NO x abatement is therefore necessary. In the present paper we firstly review the NO x formation mechanisms, proving that for applications of fluidized bed combustion, fuel NO x is the main consideration, and the contribution of thermal NO x to the emissions insignificant. We then assess the deNO x techniques presented in the literature, with an updated review and special focus upon the techniques that are applicable at CaPa. From these techniques, Selective Non-catalytic Reduction (SNCR) using ammonia or urea emerges as the most appropriate NO x abatement solution. Although SNCR deNO x is a selective reduction, the reactions of NO x reduction by NH3 in the presence of oxygen, and the oxidation of NH3 proceed competitively. Both reactions were therefore studied in a lab-scale reactor and the results were transformed into design equations starting from the respective reaction kinetics. An overall deNO x yield can then be predicted for any operating temperature and NH3/NO x ratio. We then present data from large-scale SNCR-experiments at the CFBC of CaPa and compare results with the lab-scale model predictions, leading to recommendations for design and operation. Finally the economic impact is assessed of implementing SNCR-technology when applying an NH3 SNCR or urea SNCR to the CFBC at CaPa. [Copyright &y& Elsevier]

The structural property of soot particles released during the pellet combustion of different municipal solid waste (MSW) was comparatively investigated through high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-Ray diffraction (XRD). The results showed under the same combustion condition, soot particles generated from different waste components have the same typical core-shell shape. But soot mass and aggregate morphology were strongly dependent on waste component material. When plastic (textiles) waste was burned, the soot obtained featured a much higher mass and more compact morphology with larger particle size compared to that from burning biomass and kitchen waste. Nanostructural characterization results revealed that paper and kitchen waste possessed the highest graphitization degree in soot, followed by wood waste, textiles, and plastic. Additionally, with the increasing addition of plastic in the mixed waste, the flame temperature was slightly reduced. And the soot was formed a lot and became more disordered in the nanostructure with shorter, more tortuous fringes and larger separation distances, which suggested a higher oxidation tendency. The A D1 /A G ratio had a linear relationship with the fringe separation distance and fringe tortuosity, with R2 values of 0.824 and 0.847, respectively. • Soot from burning municipal solid waste was comparatively studied. • Morphology and nanostructure varied largely among the soot samples. • Biomass fraction formed soot particles with well graphitic nanostructure. • Fringe characteristics play an important role in reactivity. • Plastic in mixed MSW enhanced the soot reactivity. [ABSTRACT FROM AUTHOR]

Fine particulate matter (PM) emission from biomass boilers for non-industrial heating represents one of the most important causes (together with the transport sector) of air pollution, in particular during winter. Separation technologies for fine PM are already well-known and adopted on an industrial scale, as a consequence of strict limits set by national and international regulations. On domestic boilers, the same technologies utilized on an industrial scale are not feasible due to high investment costs. Moreover, the emission limits for small size biomass boilers are higher than for industrial boilers, so high efficiency separation technologies are not needed, and are sometimes not present at all. The main goal of the paper is the development and testing of a mathematical model that is able to foresee the PM removal efficiency of a wet scrubber device. After an experimental validation based on several tests, it was possible to approach the preliminary design of an innovative wet scrubber, which is described in the paper. The main characteristics are (i) removal efficiency over 99.9%, (ii) specific energy consumption under 36 kJ m −3 , which is an industrial reference, and (iii) relatively low investment, operation and maintenance costs. [ABSTRACT FROM AUTHOR]

• Fuel quality of biomass will be improved after undergoing torrefaction pretreatment. • Correlation between torrefaction condition and biomass structural feature are summarized. • Compositional variation and elemental distribution for torrefied biomass are exemplified. • Torrefaction is beneficial to reducing the emission of gaseous pollutant and PM. Biomass is renewable and clean energy source, the utilization of biofuel derived from biomass is an important strategy to reduce CO 2 emissions and mitigate the greenhouse effect during power generation process. Biomass poses obstacles to its wide utilization in industry because of the self-characteristics such as low calorific value, high water content, poor grindability and easy corrosion decomposition. In the modern biomass conversion technologies, torrefaction pretreatment technology has attracted much attention. Torrefaction technology can generally be divided into dry torrefaction and wet torrefaction. Meanwhile, the dry torrefaction can be divided into inert torrefaction and oxidative torrefaction. From the perspective of economy and practicality, oxidative torrefaction has more prospects and advantages, such as high efficiency, low energy consumption, short pretreatment duration, et al. Based on the existing researches, a review was conducted on the field of biomass torrefaction pretreatment. Firstly, the detailed effects of torrefaction temperature, atmosphere, pressure and duration on the compositional and elemental variations of biomass were explored. Moreover, the efficiency analysis of inert torrefaction, oxidative torrefaction and flue gas torrefaction for different type biomass were also summarized and reviewed systematically. In this paper, the fuel quality and emission characteristics of torrefied biomass during thermal conversion process were also discussed respectively. Thence, the challenges and prospects of biomass torrefaction technology for the future development were also analyzed. Finally, future directions and technological challenges associated with the torrefaction process are proposed and its application potential is also evaluated. [ABSTRACT FROM AUTHOR]

Grate boilers are widely applied in biomass combustion for heat and energy generation. However, grate-firing systems often suffer from low efficiency and high emission. Computational fluid dynamic (CFD) becomes increasingly popular as a flexible method to obtain the detailed combustion behaviors in the furnace, and to optimize the performance of existing grate boilers. This paper presents efforts toward a reliable baseline CFD model for an industrial biomass-fired grate boiler, where the structure of the fuel-bed was sufficiently considered. The combustion performances in the furnace were investigated experimentally and numerically by coupling the fuel bed and freeboard, to clarify the impact of bed structure on the simulation accuracy. Results show that when the bed structure has been taken into account, the predictions are in better agreement with the various measurements, as the deviations between them are all within 10 %. Moreover, the flame center drops, the total heat transferred to the water-cooled walls increases, and the residence time of flue gas is greatly prolonged from 2.76 s to 3.90 s, resulting in a distinct difference of the temperature and species patterns in the freeboard. The simulations will provide valuable theoretical guidance for the accurate modeling of grate-fired boiler. [Display omitted] • A baseline model is proposed for accurate modeling of biomass-fired grate boiler. • Effect of fuel-bed structure on the simulation of grate boiler is clarified in detail. • Bed structure greatly affects the predicted temperature and species patterns. • Flue gas residence time and heat transfer are also highly impacted by bed structure. [ABSTRACT FROM AUTHOR]

The present paper reports the results of the design optimization of an air manifold utilized for delivering the air necessary for the combustion process in a biomass-fired batch boiler. A CFD model is built and validated by using experimental data. The numerical model is used to improve the device performances by reducing the entropy generation, considered as a measure of the effectiveness of the design. Other parameters, namely outlet velocities, are also monitored in order to guarantee an efficient combustion process. Four different designs of the manifold, characterized by a progressive reduction in entropy generation, are proposed and then compared with the base case. In each design step possible sources of irreversibility, such as corners, sharp variation of the flow direction, etc. are smoothed, for example by rounding the corners or by accompanying the flow in its directional changes. For all the cases, entropy generation is monitored and a reduction in its value of ∼10 times is observed if the first and last designs are compared. Values of velocities and pressure drops are monitored to confirm the acceptability of the improved designs. Finally, entropy generation and pressure drops are analysed for varied air flow controlled by the fan power. • An entropy generation analysis is developed to improve the design of an air manifold. • The elimination of the main sources of irreversibility allows to improve the performance. • Entropy generation minimization demonstrates to be an effective tool for design optimization. [ABSTRACT FROM AUTHOR]

In the paper, a novel dual circulating fluidized bed (DCFB) reactor is introduced, which can be widely applied in catalytic cracking, chemical looping combustion, coal/biomass combustion and gasification, and gas adsorption, etc. The study mainly investigates the effects of specific operating parameters on pressure balance and solid circulation rate, including total solids inventory, riser gas velocity, bubbling fluidized bed gas velocity and pot-seal gas velocity. It is found that changes of those parameters lead to variations in pressure balance and riser axial voidage in DCFB system, and further affect solid concentration and solid circulation rate in the system. To be more specific, total solids inventory, riser gas velocity and bubbling fluidized bed gas velocity have a major impact on solid concentration and solid circulation rate, while pot-seal gas velocity only exerts a minor impact. Besides, the changing of overall pressure drop across the bubbling fluidized bed is consistent with variations in pressure drops in the other parts of the system, with the former equaling △ P r + △ P c + △ P p-t + △ P ud1 + △ P ud2 . In this way pressure balance in the system is maintained. Eventually the paper reaches the conclusion that relevant operating parameters can be adjusted to control pressure distribution and solid circulation rate in different parts of the system and further to ensure the safe and stable operation of DCFB reactors. [ABSTRACT FROM AUTHOR]

The residual woody biomass (a.k.a. harvest slash) produced during forest harvest operations in the Pacific Northwest is generally collected into piles and burned and/or left on the forest floor to decompose. Producing drop-in biofuels from this residual cellulosic feedstock can provide an alternative use for this unused resource while simultaneously displacing petroleum based fuels. Utilizing a ‘Woods-to-Wake’ (WoTW) Life Cycle Assessment (LCA) approach, which is comparable to a Well-to-Wake (WTW) LCA for petroleum based aviation fuel, this paper assesses the environmental implications of feedstock recovery, production, and utilization of residual woody biomass based biojet fuel. This paper also presents a comparative assessment of the environmental implications of substituting petroleum based jet fuel with that of residual woody biomass based biojet fuel. The bioconversion process presented in this paper uses a mild bisulfite pre-treatment of the feedstock to liberate the C5 and C6 sugars which then go through enzymatic hydrolysis and saccharification to produce fermentable sugars. The sugars are then converted to bio-jet fuel (iso-paraffinic kerosene, IPK) using a proprietary biocatalytic fermentation and oligomerization process. The WoTW environmental implications of producing woody biomass based jet-fuel are then compared to the WTW environmental impacts of producing petroleum based jet-fuel. The results reveal that the WoTW global warming impact of residual wood based bio-jet fuel represents a 78% improvement over the WTW global warming impact of petroleum-based jet fuel. [ABSTRACT FROM AUTHOR]

In this paper, an innovative process layout to promote the integration among the chemical looping combustion of biomass, solar hydrogen, and carbon methanation is proposed and numerically investigated. The core of the layout consists of a multiple interconnected fluidized bed (MFB) system for the chemical looping combustion of solid fuels. A coupled hydrodynamic and reactive model of the system was developed and applied to evaluate solid circulation rate, solid bed levels in different parts of the system, flue gas composition and flow rate, and power production. The performance of the system was evaluated by considering chemical and physical properties of olive wood, a biomass typical of Mediterranean area, as fuel and of CuO supported on zirconia as oxygen carrier, respectively. A complex reaction scheme comprising both gas–solid heterogeneous and gas-phase homogeneous reactions was considered. Results corresponding to steady state operation of MFB are presented in conjunction with an analysis of the operability of the system under the considered ranges of operating conditions. By considering that only energy coming from renewable sources (such as photovoltaic panels or wind turbines) was fed to the electrolysis cell (EC) array, the potential of the proposed process to be used as an energy storage system was assessed. Unlabelled Image • A mathematical tool for evaluating the performances of a novel system was developed. • Heat and mass balances were coupled with thermodynamic and hydrodynamic model. • Through numerical simulation, system steady state operation ranges were evaluated. • High CH 4 yield can be reached only accounting for at least two methanation units. • A 17% electric energy storage efficiency can be achieved, as long as near-zero CO 2 emissions. [ABSTRACT FROM AUTHOR]

The main goal of this paper is the evaluation of combustion and grindability of torrefied palm kernel shells (PKS) obtained in a pilot-scale installation. The torrefied samples were prepared in different time conditions and temperatures, ranged from 220 to 300 °C. The physico-chemical properties were identified. Thermogravimetric analyses (TG-DTA) were used for characterization of the combustion performance and evaluation of the activation energy E α . The grindability of the pre-treated biofuel was investigated in a pilot-scale, coal bowl-roller milling unit. The results were compared to those of the raw PKS and bituminous coal. Torrefaction was found to increase carbon C content and HHV by 2–33 and 2–26%, respectively. Moreover, the combustion characteristics of the torrefied PKS samples are close to each other, but the ignition and burn-out temperatures differ significantly. The torrefaction changes the activation energy E α and it approaches the E α values to those of coal. Both the torrefaction temperature and residence time significantly affect the grindability. The grinding effect of PKS torrefied at 220 °C reached the value of 10%, whereas after torrefaction at 300 °C it doubled. The torrefaction considerably improves the properties and combustion behaviour of biomass, which is a good predictor for burning and co-burning in industrial units. • Torrefaction increase the higher heating value of the palm kernel shells. • Ignition and burn-out temperature of the torreffied PKS samples differ significantly. • Torrefaction temperature and residence time improves the grindability. • The activation energy decreased with the carbonization degree increase. [ABSTRACT FROM AUTHOR]

Oxy-MILD (Oxygen Moderate and Intense Low-Oxygen Dilution) combustion is one of the most promising technologies for the mitigation of CO 2 emissions from coal-fired furnaces, benefiting from its good performance in flame-temperature controlling and NOx reduction. Under oxy-MILD mode, the combustion or co-firing of biomass (CO 2 -neutral) can achieve "negative CO 2 emissions". In this paper, oxy-MILD biomass co-firing is numerically studied by CFD modeling for the IFRF furnace NO.1, where Guasare coal and Olive waste are co-fired under air-MILD and oxy-MILD conditions, respectively. The effects of biomass co-firing ratio (0–30%, energy basis) and atmosphere on the temperature and heat flux distribution, and NOx emissions are discussed. The modeling results show that under MILD combustion mode, both oxy-combustion and biomass co-firing can generate a more moderate temperature distribution and lower NOx emissions than air-combustion and coal combustion, respectively. When biomass co-firing ratio increases from 0% to 30%, under oxy-MILD combustion mode, the peak temperature linearly decreases by 28 K and the NOx emissions decrease by 141 ppm; while under air-MILD combustion mode, the peak temperature increases by 15 K and the NOx emissions decrease by only 73 ppm. This modeling work suggests that oxy-MILD biomass co-firing is a more promising technology to achieve "negative CO 2 emissions" in coal combustion, with lower furnace temperatures as well as NOx emissions. • Oxy-MILD biomass co-firing is numerically studied by CFD modeling. • Oxy-MILD biomass co-firing generates a more moderate temperature filed. • NOx emissions from Oxy-MILD biomass co-firing are lower. • Oxy-MILD biomass co-firing is more promising to achieve "negative CO 2 emission". [ABSTRACT FROM AUTHOR]

The paper presents experimental investigation on temporal release of potassium (K) from single biomass pellet combustion by Flame Emission Spectroscopy (FES). Through the analysis of spontaneous emission spectra and a calibration procedure, the concentration of gas phase potassium, temperature and thermal radiation during the whole process of biomass pellets combustion in a Hencken burner were measured simultaneously. Camphorwood and rice husk with volatile matter 87.93%, 69.12%, respectively, and K 2 O content from the ash analysis 7.99%, 1.8%, respectively, were used in the experiment. The effects of biomass composition and moisture content in the pellet on the temporal release of K were analyzed. Experimental results showed the three stages (devolatilization, char, and ash stage) of biomass pellets combustion can be distinguished by the changing points of K concentration, temperature and thermal radiation curves obtained by the FES. The volatile content in biomass pellet has effect on the release behavior of K. The change of moisture in biomass pellet may affect significantly the ratio of K release from biomass pellet with low volatile. The experimental investigation proves FES is feasible for on-line monitoring the K release and combustion process of biomass pellet. [ABSTRACT FROM AUTHOR]

The combustion processes of biomass occurring in furnaces run with an emission of exhaust gas consisting of groups of chemicals which occur both in gaseous and particulate-bound form. The purpose of the work presented in this paper was to investigate the impact of wood combustion processes occurring in domestic heating units (DHUs) on the emission of particulate matter (PM) and other exhaust components. The process of combustion was divided into three steps: A. firing, B. combustion, and C. post-combustion. During fuel burning, the weighting platform was used to measure variations in the mass of fuel and a gaseous analyzer was used to measure gaseous exhaust components such as CO 2 , CO, O 2 and SO 2. A dust sampler equipped with a dilution tunnel, a filter holder and a pump were installed in the stack. The samples of PM were collected on quartz fiber filters with a diameter of 47 mm. The PM was then analyzed for the presence of inorganic and organic components. The results obtained in the studies confirmed the influence of using the accumulation layer on the emitted exhausts. Application of accumulation layer led to decrease the emission of gaseous fumes (NO, NO x and SO 2), although, the CO and PM emission were higher. One also observed the impact of combustion phase on the chemical composition of collected PM. The highest measured concentrations of analyzed PAH compounds were determined for acenaphthene (Ace) and benzo(a)pyrene (BaP). In all analyzed events BaP mostly contributed to the budget of PAHs in the final phase of burning: during the post-combustion process, when the temperature in the combustion chamber decreased. The application of the accumulation layer enabled to decrease the BaP concentration in the ignition phase of burning. The highest concentration of Ace was observed for the combustion phase using the Stove 1, while in the Stove 2, both with and without an accumulation layer, the Ace concentration was higher in the initial phase of burning. [ABSTRACT FROM AUTHOR]

Crop residue burning is an important source of air pollutants and strongly affects the regional air quality and global climate change. This study presents a detailed emission inventory of major air pollutants from crop residue burning for the year of 2014 in China by the bottom-up method. Activity data were investigated for 296 prefecture-level cities. Emission factors were determined for indoor and in-field burning separately. Regional differences were considered for the proportion of residue burned (PCRB), the ratio between indoor and in-field burning, and the ratio of straw to grain production. The emissions were estimated at prefecture-city level as the first step; then they were redistributed within a city based on 1-km resolution land-use, MODIS fire counts, and rural population. Temporal variation was determined according to farming practices in different regions and MODIS fire counts. Uncertainties were estimated using the Monte Carlo method. The total emissions from crop residue burning in China were estimated to be 0.13 (−47–92%) for BC, 0.71 (−48–92%) for OC, 1.77 (−48–91%) for PM 2.5 , 2.04 (−50–100%) for PM 10 , 0.16 (−59–133%) for SO 2 , 0.53 (−55–105%) for NO X , 0.12 (−47–93%) for NH 3 , 1.07 (−55–102%) for CH 4 , 1.85 (−43–74%) for NMVOC, 18.33 (−46–85%) for CO and 305.20 (−45–80%) for CO 2 , in unit of Tg yr−1. Our results are remarkably lower than those reported in previous studies, mainly because of the PCRB has decreased significantly in recent years. For most of the pollutants, indoor burning accounted for about 50–70% of the emissions. Rice, wheat and corn contributed more than 85% of the emissions, but their relative contributions varied a lot with region and season. High emissions were mostly located in the eastern China, central China and northeastern China, and temporally peaked in April, June and October, with different intensities in the north and the south. This study provides a useful basis for air quality modeling and the policy making of pollution control strategies. • This paper presents an up-to-date and high-resolution inventory of air pollutant emissions from crop residue burning in China. • City-level activity data and high-resolution land use, fire counts and population were combined for spatial distribution. • Farming practices in different regions and statistics of fire counts were used to determine temporal distribution. • High emissions were generally located in Eastern, Central and Northeastern China, and temporally peaking in April, June and October. [ABSTRACT FROM AUTHOR]

• (Co-)combustion of biomass, biochar, coal, municipal solid waste were investigated. • Thermal degradation was analyzed using Coats-Redfern model. • A synergistic effect was detected between biomass, biochar, coal and municipal solid waste. Investigation of thermal behaviors of biomass waste, biochar, coal, municipal solid waste (MSW) and their mixtures were aimed in the present study using both thermogravimetric analysis and differential scanning calorimeter techniques. In fact, this paper intends to interpret the influence of mixtures on activation energy. In this purpose, Coats and Redfern were used. Then, the relative error Δ m e r r o r was calculated to quantify the synergism degree. Precisely, it was about 5.34% for biomass/coal, 5.52% for biomass/cardboard, 5.67% for biomass/biochar, 5.93% for biomass/synthetic rubber and 6.05% for biomass/plastic mixtures. This phenomenon was justified by the interaction between C-C bond of biochar, coal and MSW radicals with C-H and C-O bonds of biomass. [ABSTRACT FROM AUTHOR]

[Display omitted] • A zirconium oxide porous inert material was placed inside a biomass burner. • A VOC sampling train was designed, implemented, and its retention time validated. • New, more nuanced data on VOC-PM relationship was obtained. The present paper delves into experimental data to assess the effects of the inclusion of a zirconium porous medium in the emissions of a laboratory-scale biomass combustor, with a focus on particulate matter and volatile organic compounds. While other studies have focused on the effects of the material on solid particulate matter or gaseous emissions, this research is focused on volatiles, their capture and storage. A novel sampling train for the capture of volatiles has been designed based on active carbon adsorption on a refrigerated environment, and its performance was evaluated through thermogravimetric analysis, showing the affinity of this porous medium towards lighter organic compounds. The retention time of the sample was also studied, and the data revealed that after three to six hours the sample had degraded significantly when stored in airtight plastic bags inside a glass desiccator at 22 °C. An analysis of the particulate matter emitted was also carried out. Volatile organic compounds were also found to follow the behavior of particulate matter, with the scenarios where low solid particles were emitted being also those in which volatiles release was minimized. [ABSTRACT FROM AUTHOR]

In this paper, the effect of alkaline-earth metals (AEMs, Ca, Ba, and Sr) on the performance of CuO/ZrO 2 oxygen carriers (OCs) and the hemical looping with oxygen uncoupling (CLOU) process of wheat-derived hydrochars with these Cu-based OCs were investigated. The results showed that after multiple cycles, the crystal phases of modified Cu-based OCs were the same as that of pure CuO/ZrO 2 OC without any interaction between them. Due to the catalytic effects of AEMs, an increase in the decomposition of wheat and hydrochar-235 in modified Cu-based was observed at 500 °C. The combination of Ca and HTC promotes reoxidation, while Ba and Sr inhibit reoxidation. Notably, the Cu-based OCs exhibited moderate agglomeration after 20 redox cycles at 950 °C. The results of the kinetic analysis indicate that the chemical order models and diffusion models can suitably describe the first combustion stage for wheat and hydrochars with Cu-based OCs, respectively. The geometrical contraction model was also found to most suitably describe the second combustion stage of all samples. These results suggest that a combination of hydrothermal carbonization pretreatment with AEMs modification is an efficient approach for CLOU using CuO-based OCs. [Display omitted] • AEMs enhanced the decomposition under 500 °C without interactions with CuO OC. • Simultaneous combustion and reoxidation enhancement of hydrochar-235 was observed. • The reoxidation activity of CuO was improved by Ca but inhibited by Ba and Sr. • Moderate agglomeration of CuO was observed after 20 redox cycles at 950 °C. • The kinetics of biomass combustion was estimated using the Coats-Redfern method. [ABSTRACT FROM AUTHOR]

The air pollution in Hotan, Xinjiang is serious and the high concentration of polycyclic aromatic hydrocarbons (PAHs) cannot be ignored. Studies on the characteristics of PAHs in the region are still limited. In this paper, PM 10 and PM 2.5 samples were collected from the urban area of Hotan in summer and winter, and the concentrations, sources and contributions to hydroxyl radicals (·OH) of 12 PAHs were analyzed. The mean concentrations of PM 2.5 /PM 10 -bound PAHs were much higher in winter (150 ± 38.8 ng/m3 and 156 ± 38.1 ng/m3) than in summer (6.34 ± 6.28 ng/m3 and 7.64 ± 6.75 ng/m3), with greater contributions from medium and high molecular weight PAHs. PAHs are mainly derived from vehicle emissions, coal and biomass combustion, with coal combustion making the largest contribution to ·OH concentrations. The combination of air mass trajectory clustering and potential source contribution factor analysis (PSCF) revealed that long-range transport contributed less to the PAHs content, and local domestic source emissions dominated. Studies have shown a significant positive correlation between PAHs and ·OH concentrations, indicating that PAHs are oxidatively toxic to humans. Controlling PAHs emission in winter in Hotan and reducing the concentration of PAHs in respirable particulate matter will help to reduce the damage to human health. • PM 2.5 /PM 10 –bound PAHs in urban areas of Hotan City were studied in winter and summer. • PAHs mainly coalesced in fine particulate matter (PM 2.5), not PM 2.5-10. • PAHs were emitted from local mixed sources, with coal combustion and vehicle emissions being the main sources. • MMW-PAHs and HMW-PAHs showed a good positive correlation with ·OH concentration. [ABSTRACT FROM AUTHOR]

• A biomass ignition delay model is developed. • The model was validated against seven biomass fuels yielding a very good agreement. • The model is able to accurately distinguish between different biomass fuels. Ignition is a critical step of the combustion process of biomass, due to its substantial impact on flame characteristics, process efficiency, and pollutant formation. This paper aims to develop a robust zero-dimensional ignition model as an effective tool to quickly estimate the ignition behaviour of biomass fuels. The numerical approach integrates an established devolatilization model with a well-tested mechanism for gas-phase reaction kinetics. The ignition delay time is determined from the sum of the devolatilization time and ignition time of the evolved gas species, as specified by the maximum in the OH radical concentration. The central premise of the modelling routine is that kinetics govern the ignition delay during biomass initial heating and thermochemical conversion which makes the elemental fuel composition the most important fuel property and heating rate the most important reactor condition. The predictions of the model are tested and verified against published experimentally measured ignition data for seven pulverized biomass fuels and are found to be in good agreement. The model for the first time can reasonably distinguish ignition behaviours of different biomass fuels, enabling its use in wider industrial applications. [ABSTRACT FROM AUTHOR]

Recently the performance of dual fuel strategy on multi-cylinder engines over the whole engine map has received increasing attention. This research focuses on the potential of Homogeneous Charge Induced Ignition (HCII) combustion fueled with gasoline and diesel meeting Euro V emission standard through the whole operating range using a simple after-treatment system. This combustion mode utilizes a port injection of high-volatile fuel (gasoline) to form a homogeneous charge and a direct injection of high ignitable fuel (diesel) near the Top Dead Center (TDC) to trigger combustion. In this paper, an experimental and numerical investigation of the combustion characteristics and emission formation of HCII on a multi-cylinder heavy-duty engine is conducted. The effects of gasoline ratio ( R g ), one of the most important parameters in dual-fuel mode, are explored and analyzed in detail. A R g of 70–80% is recommended for better combustion and emission performance at the operating condition in this paper. HCII also turns out to be an effective strategy to reduce NOx and soot emissions at the same time. Furthermore, the high THC and CO emissions of HCII combustion can be eliminated using Diesel Oxidation Catalyst (DOC). Then the HCII strategy was optimized through the whole operating range showing a great potential of meeting Euro V limitations only with DOC as an after-treatment device. The fuel consumption also reduced with dual fuel strategy. [ABSTRACT FROM AUTHOR]

The interest in bio-CCS technologies is growing due to their potential to reduce CO 2 emission in power generation. Oxy-co-firing in fluidized-bed units is one of the available techniques to develop bio-CCS, offering wide fuel flexibility and low SO 2 and NO x emissions. This paper discusses the results of an experimental campaign carried out in a lab-scale fluidized bed reactor. The work focuses on the influence of limestone when oxy-firing blends of lignite and corn stover. Two different types of limestone with two Ca:S molar ratios were tested, and operational conditions were selected to compare the mechanisms governing desulphurization. Emissions of SO 2 , NO and HCl, together with deposition rates and ash mineralogy are studied in the paper. SO 2 capture increases with the Ca:S ratio and bed temperature, but to a different extent depending on the limestone fragmentation. The amount of NO emitted rises with the Ca:S ratio and the presence of calcined limestone (indirect desulphurization). The HCl concentration in the gas phase is dominated by alkali sulfation. Finally, the conditions for the highest desulphurization efficiency diminished the deposition rates, but increased the risk for chlorine-induced corrosion. [ABSTRACT FROM AUTHOR]

This Short Communication Paper approaches the CO 2 emissions from forest biomass produced in sustainable managed forests from aspects related to photosynthesis and variations in vitality and capability of CO 2 uptake, depending on i.a. different rotation periods and management regimes. These aspects are ignored or diminished in most other analyses on the subject as those analyses typically are based on simplified rigidly structured models. This Short Communication Paper suggests application of more relevant methodologies closer to actual real conditions. Two CO 2 issues are covered; the CO 2 balance between growth and harvesting of biomass in sustainably managed forests, and combustion of woody biomass in comparison with fossil fuels with regard to CO 2 emissions. The analysis of the first issue leads to the conclusion that biomass harvested from sustainably managed forests should be regarded as “carbon neutral” as the vitality and CO 2 absorption is sustained and kept on the same (or better) level. Moreover, to transform old pristine forests to young vigorous forests would be an effective (long term) means of reducing atmospheric CO 2 . Regarding the second issue, we notice that some other authors of papers on bioenergy claim that biomass would not be “climate neutral” when used for energy as, for generation of a given energy amount, more fixed carbon is released from biomass than from fossil fuels. In our opinion, authors of these papers apply obsolete, too general or sometimes illogical default values. This Short Communication Paper suggests that emissions from combustion of forest biomass should be compared with emissions from coal as it is the most common and relevant fuel to replace. Also additional emissions from mining/harvesting, transport, leakage, etc. should be included both for biomass and for reference fuels like coal, gas, and oil. The comparison should also be based on state-of-the-art technology, which for biomass would mean i.a. flue-gas condensing and efficient fuel treatment. Under these conditions, typical biomass applications for energy would be both carbon neutral and climate neutral. [ABSTRACT FROM AUTHOR]

• Dynamic model of the integrated biomass power-carbon capture plant is developed. • Dynamic interactions between biomass power and carbon capture systems are analyzed. • Operating costs of carbon capture and power generation are evaluated. • Capacities of power output and negative CO 2 emission of the plant are identified. • Power load ramping performance under different regulation methods is compared. Biomass direct-fired circulating fluidized bed boiler has distinguished advantages of strong fuel adaptability, high combustion efficiency and low NO X emission, thus has been regarded as one of the important pathways for biomass utilization. Retrofitting the biomass direct-fired circulating fluidized bed boiler power plant (BCFBP) with carbon capture can strongly support the goal of carbon neutrality, because negative CO 2 emission is achieved during the power generation. Nevertheless, the biomass direct-fired circulating fluidized bed boiler is sensitive to the combustion condition, high in operating costs, slow in dynamic response and poor in regulating capability. The integration of carbon capture may pose significant changes on the operating safety, efficiency and flexibility. A comprehensive analysis is thus required to understand the interactions between the BCFBP and carbon capture under various operating conditions. To this end, this paper develops a plant-wide dynamic model for a 130 ton/h BCFBP integrated with solvent-based post-combustion carbon capture (PCC) system. Multi-stage models of biomass combustion, steam generation and steam turbine-feedwater heater systems are developed to represent the dynamic interactions among biomass, heat, electricity and carbon, so that the impacts of BCFBP operation on the PCC process can be evaluated. Detailed BCFBP-PCC connecting system model are also developed to reflect the dynamic changes of steam/water flowrate, pressure and temperature in the steam turbine system caused by the integration of PCC. The developed model is then used to analyze the system interactions, operating costs, negative carbon capability and load ramping flexibility of the integrated BCFBP-PCC. Results show that the integration of PCC 1) causes significant impacts on the water/steam parameters of the steam turbine-feedwater heaters behind the reboiler steam extraction point; 2) reduces the power output of BCFBP by 26.12 % under 95 % CO 2 capture level condition; 3) expands the power output variation range of the BCFBP from 22.3 to 36.6 MWe and provides the negative CO 2 emission capacity from 2.2 to 6.9 kg CO 2 /s; 4) offers a feasible way to improve the power ramping performance through flexible distribution of the water/steam in the steam turbine-feedwater heater system. This paper provides specific guidance for the design, retrofit and operation of the BCFBP-PCC plant. [ABSTRACT FROM AUTHOR]

Engineering efforts to handle contemporary energy supply challenges and mitigate pollutant emission lead towards more complicated systems. Power plants are supplementing with additional processing units, alternative production modes and higher level of automation. Wind and solar sources, biomass combustion, gasification, carbon capture and storage (CCS), and cogeneration have appeared as important players in the energy systems. The increasing complexity comprises a risk that the systems become less manageable and less stable than currently. Traditional steady-state engineering methods cannot fully address these challenges that are inherently dynamic in their nature. Dynamic process simulation appears as important tool to the systems design and optimisation tasks. A large variety of dynamic process modelling and simulation approaches has been presented recent years. This paper presents a brief review of methods and simulation packages that are generally applied for studying energy systems' transient behaviour. A CCS capable power plant is presented as an example of utilizing dynamic process simulation for virtual evaluation of a novel electricity production concept. The modelling was performed using two simulators Apros and Aspen Plus Dynamics, which were linked together for dynamic simulating the full chain of cryogenic oxygen distillation, oxy combustion, turbine islands and carbon dioxide purification and liquefaction operations. • Dynamic simulations for design and optimisation of contemporary energy systems have been reviewed. • A case study for evaluating oxy combustion CFB boiler cycle with carbon capturing is presented. • Co-simulation with two dynamic process simulation software: Apros and Aspen Plus Dynamics were shown. • Flexibility aspects of oxy combustion power plant are discussed. [ABSTRACT FROM AUTHOR]

Abstract Functional groups evolution characteristics of biomass during the combustion process have a significant influence on the combustion mechanism because they directly affect the diffusion of oxygen to the surface of biomass. In this paper, microcrystalline cellulose was chosen as the feedstock. The functional groups evolution characteristics were studied using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and thermogravimetric (TG) analysis was also conducted to be compared. In situ DRIFTS and TG of cellulose were performed from 20 °C to 500 °C at different heating rates in different atmospheres. The results of in situ DRIFTS showed that oxygen-containing functional groups firstly increased and then decreased with increasing temperature, while hydrogen-bonded functional groups showed the opposite characteristics. Compared with TG experiments, it can be obtained that the O–H bonds maintained the crystal structure of cellulose at low temperature, and promoted further reactions at high temperature. The production of C=O functional groups prevented further decomposition of cellulose. The relationship of combustion kinetics during the initial stage of combustion and in situ functional groups evolution characteristics were obtained. This study demonstrated that the combustion kinetics can be predicted by the surface functional groups evolution of biomass, which provides a potential way for studying biomass combustion. [ABSTRACT FROM AUTHOR]

Abstract In the framework of the INDAAF (International Network to study Deposition and Atmospheric chemistry in AFrica) programme, part of the ACTRIS European Research Infrastructure for the long-term observation of Aerosols, Cloud, and Trace gases, this paper aims to study trends and seasonal variability of surface atmospheric NO 2 and HNO 3 concentrations, and OMI (Ozone Monitoring Instrument) NO 2 over 6 sites in tropical Africa. Sites are located in west and central Africa to represent the major African biomes: dry savanna (Banizoumbou, Niger and Katibougou, Mali), wet savanna (Djougou, Benin and Lamto, Côte d'Ivoire) and forest (Bomassa, Republic of Congo and Zoétélé, Cameroon). Ground-based NO 2 and HNO 3 concentrations were obtained over the period 1998–2015 using INDAAF passive samplers at a monthly basis, and NO 2 Vertical Column Densities (VCDs) from OMI for a 1° grid cell around each sites were obtained from 2005 to 2015. Mean annual NO 2 concentrations ranged from 2.3 ± 1.2 to 0.9 ± 0.4 ppb from dry savannas to forests, representing a north south gradient. In dry savannas, we observe two concentration peaks of NO 2 appearing at the beginning and the end of the wet season both for ground-based and satellite measurements, whereas at wet savannas and forest sites, NO 2 concentrations are highest in the dry season. The seasonality of surface NO 2 observations provide further evidence for a large role of microbial soil NOx emissions in dry savannas and of biomass burning NOx emissions in wet savanna and forest sites. Mean annual HNO 3 concentrations ranged from 0.4 to 0.5 ppb in dry and wet savannas to 0.2–0.3 ppb in forest. In dry ecosystems, higher HNO 3 concentrations are measured in the early wet season, consistent with NO 2 results. The analysis of a long-term dataset of surface O 3 concentrations indicates that HNO 3 production can mainly be explained by the photooxidation of NO x. Mann-Kendall and Seasonal Kendall statistical tests showed that NO 2 surface concentrations have a significant decreasing seasonal and annual trends at multiple sites (p-value < 0.05) ranging from −2.96% yr−1 (at Zoétélé) to −0.64% yr−1 (at Banizoumbou). HNO 3 results indicate no trends except at Bomassa (1.07% yr−1). The decreasing NO 2 ground-based concentration trends observed in wet savannas sites are correlated with OMI NO 2 decreasing trends at these sites. Trends obtained for NO 2 concentrations in wet savanna and forest ecosystems are consistent with trends of NOₓ biomass burning emissions. Highlights • Long term data of surface and column nitrogenous gases from major African biomes. • North-South latitudinal negative gradient in surface concentrations of NO 2 and HNO 3. • Microbial soil emissions of NOₓ are predominant in dry savannas. • Biomass burning emissions of NOx are predominant in wet savanna and forest sites. • NO 2 annual and seasonal decreasing trends at most of west and central Africa sites. [ABSTRACT FROM AUTHOR]

Abstract Rare earth elements (REEs) are highly important in the modern society as a result of their wide use in various fields of industry. Their high supply risk and increase in demand has led to classification as critical materials, and consequently, new resources for REEs are being prospected widely. Coal fly ash has been suggested as a possible secondary resource for REEs, but very little information is available regarding REE occurrence in biomass or peat derived fly ash. In this paper, fly ash samples from commercial power plants using peat and biomass as fuel were studied for REEs. The average concentration of REEs was 530 ppm, with up to 920 ppm in one fly ash. Five out of seven fly ashes were identified promising for profitable REE recovery according to outlook coefficients of >0.7 and critical REE content of >30%. Four fly ashes were found to exhibit medium REE enriched distributions, whereas three fly ashes displayed light REE enriched distributions. These enriched distribution patterns, as well as the observed Gd, Ce, Eu, La, and Y anomalies in the patterns, are proposed to originate mainly from the granitic bedrock at the fuel source. Additionally, positive correlation between REEs and iron was found, indicating REE association with iron minerals. Graphical abstract Unlabelled Image Highlights • Average REE concentration of 530 ppm, up to 920 ppm in one fly ash • Five out of seven fly ashes found promising for profitable REE recovery. • REE distributions exhibit enrichment for medium or light REE. • Correlation found between REE and Fe indicating REE associations with iron minerals. • Ce, Eu, La, Gd, and Y anomalies present in fly ashes. [ABSTRACT FROM AUTHOR]

Abstract As an important part of the anthropogenic aerosol, Black Carbon (BC) aerosols in the atmospheric environment have strong impacts on climate change. Recently, most remote sensing studies on aerosol components detection are limited to the inversion of aerosol optical properties, integration of chemistry models or in situ observations. In this paper, an algorithm based on Effective Medium Approximations (EMA) and statistically optimized aerosol inversion algorithm was integrated for retrieving the surface mass concentration of BC aerosols from satellite signals. The sensitivity analyses for the developed forward model proved that the volume fraction of vertical BC is sensitive to the satellite observations and significantly improved especially over bright surface targets or under polluted atmospheric conditions. By updating the forward model and retrieved parameters of the statistically optimized inversion algorithm, three cases of high aerosol loading days were retrieved from Polarization and Anisotropy of Reflectance for Atmospheric Sciences Coupled with Observations from a LiDAR (PARASOL) measurements, which shows a significant ability of BC aerosol detection. Additionally, the validation and closure studies of BC concentration retrievals also indicates an encouraging consistency with correlation (R) of 0.71, mean bias of 3.55, and root-mean-square error (RMSE) of 3.75 when compared against the in-situ observations over South Asia. The accuracy of the retrievals also demonstrates different trends under different levels of aerosol loadings, which shows a higher accuracy in biomass burning seasons (R = 0.75, RMSE = 4.04, Bias = 3.27) while exaggerates the results in the case of clear conditions (R = 0.47, RMSE = 4.83, Bias = 4.00). Finally, the uncertainties of three assumptions, including proposing uniform vertical profile for BC, neglecting light-absorbing aerosols and using spherical EMA models were discussed in our manuscript. The maximum standard deviations caused by these uncertainties on low BC aerosol volume fractions (f BC < 1%) are 0.8%, 0.35% and 0.2% while these deviations will change to 0.25%, 0.05% and 1.5% respectively under higher BC fractions (f BC > 5%). This conclusion confirmed that the proposed algorithm for BC surface concentration retrieval extends the application of satellite remote sensing in monitoring the extreme biomass burning pollution. Highlights • Satellite based BC surface concentration retrieval algorithm was developed. • Detailed sensitivities of integral forward modules of EMA and RTM were proposed. • Global high aerosol loads cases and closure validation studies of BC were tested. • Detailed uncertainties of expected assumptions in retrieval were analyzed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A new detailed kinetic model of biomass combustion and pyrolysis was developed. • The gas-phase reactions of biomass devolatization tars were considered in details. • A new oxidation mechanism has been written for hydroxyacetaldehyde. • New ThermoGravimetric Analysis experiments of beech, fir and oak were performed. • Several validation of the new mechanism against a wide set of experimental data. Abstract In the context of the growing utilization of biomass to produce energy and of the related need to decrease pollutant emissions from domestic wood combustion devices, this paper presents a new kinetic model of wood combustion considering especially in details the gas-phase reactions related to the combustion of the tars produced by the biomass devolatization. The tar production is predicted using a semi-detailed mechanism of the literature. The tar gas-phase combustion model has been built as a compilation of literature mechanisms already proposed for these species, except for hydroxyacetaldehyde for which a new oxidation mechanism has been written. Experiments on the thermochemical behavior of three types of wood (beech, fir and oak) were also performed in parallel of this work using Thermogravimetric Analysis (TGA). The new detailed kinetic model of wood combustion, BioPOx (Biomass Pyrolysis and Oxidation), has been tested against a wide range of experimental results published in literature. This model fairly reproduces experimental results for pyrolysis and combustion of biomass and its constituents, key produced tars from biomass pyrolysis, and key compounds for Polycyclic Aromatic Hydrocarbons (PAH) formation, for a wide range of experimental devices and operating conditions. [ABSTRACT FROM AUTHOR]

Abstract The vertical distribution characteristics of aerosols are key uncertain factors for studying the effect on radiative forcing and trans-regional transport of pollutants. This paper used three years (2013–2015) LiDAR measurements at a site in the Yangtze River Delta region of China to investigate the aerosol vertical distribution and transport sources of aerosol-aloft by using the Potential Source Contribution Function (PSCF) and Concentration-Weighted Trajectory (CWT) models. The results indicated that there were 230 haze days accounted for 21% of all the days, including 142 damp haze days and 88 dry haze days during the study period. The aerosols below 2 km accounted for >89% of the total aerosol optical depth (AOD). Compared to other seasons, aerosols in winter were more likely to accumulate below 1 km (>69%). In summer, although atmospheric convention was strong leading to a high planetary boundary layer height (PBLH) and the concentration of PM 2.5 was low, the AOD was largest because of high relative humidity that caused hygroscopic growth of particles. Due to the stable weather condition in winter, the PBLH was low with the largest concentration of PM 2.5 , so the occurrence of haze days was most frequent. The PSCF and CWT results revealed that the high-level aerosols mainly came from local areas; the CWT model showed considerable long-distance transports of dust from northern/northwestern China, as far as Mongolia, Gansu Province and Xinjiang Uygur Autonomous Region, in spring, autumn and winter. Southern sources were more obvious in winter that could contribute more anthropogenic aerosols and biomass burning emissions. Highlights • Long-term vertical distribution of aerosols over the YRD region from 3-years (2013–2015) LiDAR observations. • LiDAR observations were combined with backward trajectory model. • PSCF and CWT models were used to investigate aerosol-aloft sources. [ABSTRACT FROM AUTHOR]

Abstract This paper reports, for the first time, the use of Re 2 C as a catalyst for H 2 production from biomass. Re 2 C has been synthesized from rhenium and graphite using 1:1 and 2:1 stoichiometries. The highest H 2 productions are obtained at 800 °C using 10 wt % of Re 2 C catalysts. The yield of hydrogen production using Re 2 C (1:1) as a catalyst is 53.8%, while with Re 2 C (2:1) as a catalyst, it is 57.0%. The yield of 57.0% hydrogen using the Re 2 C (2:1) catalyst is the highest reported using biomass. The TPR and FTIR indicate that the Re from the Re 2 C is the main catalytic center involved in hydrogen generation from the decomposition of coconut shell. Finally, we proved that Re 2 C is a good material that can be used as a catalyst in H 2 production from biomass. Highlights • Re 2 C was synthesized by mechanochemistry using different Re:C stoichiometries. • Re 2 C was evaluated in H 2 production from coconut shell from 300 to 800 °C. • A mechanism to explain the generation of H 2 from coconut shell was proposed. [ABSTRACT FROM AUTHOR]

Abstract The results of solids accumulation and deposition in the front and rear zone of some selected steel samples located in a 400 MW coal and biomass cofired CFB boiler are presented in this paper. The analysis was particularly focused on the determination of chemical composition of the deposits in some chosen sample areas (sample surface and cross-section). The investigation results indicated that the deposits on the front sections of the samples were rich in calcium and sulfur compounds, while increasing mass fractions of alkali, alumina and silica compounds were determined on sample rear zones. The morphology and topography of the deposits were investigated and the solids accumulated on the front section (i.e. directly exposed to the flue gas flow) revealed an oriented structure, while the deposits in the rear consisted mainly of the finest ash fractions and formed a smooth and homogeneous surface. Highlights • Chemical composition of deposits depend on their location at sample outer surface. • Higher Na and K content was determined for deposits formed in sample rear zones. • The deposits in sample front section are enriched in Ca and S. • The structure of deposits in sample front section is affected by the gas flow. • Differences in elemental composition of individual deposit layers are found out. [ABSTRACT FROM AUTHOR]

The paper subsumes a framework that assesses health risk due to exposure to different fuel combustion through articulation of modern microscopic techniques, empirical equations, lung diagnostic tools and a pre-existing model that has been extrapolated to futuristic aspects (within controlled conditions). The framework was tested on 132 household cooks belonging to different age groups and using different types of fuel. The inhalable fraction released during fuel combustion varied in morphological characteristics and deposition site. Micrographs obtained using Scanning Electron Microscope (SEM) analysis of (biomass smoke) soot indicates aggregate formation attributing to a higher level of health risk. Further, abnormal ventilatory function along with higher risk (RR > 1) was more evident within biomass fuel users. The condition further exacerbates while using dung cakes due to high levels of emissions (294.3 particles/liter) that deposit in the upper respiratory tract (0.0899). Further, the population attributable risk percent (79%) calculated on the basis of cooking behavior suggests a ‘rural culture’ health determinant as clean fuel usage is not practiced as an outcome of low literacy and poor income in the region. These preliminary findings highlight the drudgery of impuissant women who are exposed to high particulate emissions on a regular basis which results in reduced lung function. Nevertheless, further cogitation is required to eliminate the limitations in this study and explore further linkages between exposure and vulnerable group to generate meaningful policy recommendations. [ABSTRACT FROM AUTHOR]

[Display omitted] • Differences in the combustion behaviour of biomass particles in natural convection and turbulent environments were experimentally identified. • Increasing turbulence intensity accelerates the heating rate and significantly shortens the burnout time of a 5 mm cellulose particle. • The volatile flame area fluctuates randomly and generally decreases with the turbulent intensity. • Volatile flame has higher local luminosity and peak temperature in low turbulence intensity. Biomass co-firing in coal-fired power plants is an appealing technology for reducing greenhouse gas emissions due to the abundant biomass resource and low cost of retrofitting the existing power plants. Burning larger biomass particles is inevitable in real boilers due to the energy-consuming grinding process. A profound understanding of the combustion characteristics of larger biomass particles in a strong turbulent gas environment inside the boiler is essential for designing and operating biomass conversion facilities. This paper presents a detailed experimental study of the effects of turbulent mixing on the combustion of biomass particles. An impinging arranged four-fan stirred turbulent furnace was established in the laboratory. Particle image velocimetry (PIV) was adopted to measure the turbulent flow field characteristics under various fan speeds. The combustion behaviours of a 5 mm homemade cylindrical cellulose pellet were investigated under natural convection and turbulent flow at 700 °C. The centre and surface temperature of the particle, the shape and peak temperature of the volatile flame, and the sequential combustion history were measured and analysed. The results show that the turbulent fluctuation velocity Vel rms increases linearly with increasing fan speed. Whether the gas environment is natural convection or turbulence has an essential impact on the combustion behaviours of the biomass particle. Increasing turbulence intensity accelerates the heating rate and significantly shortens the burnout time from 94 s to 55 s. The volatile flame area fluctuates randomly and generally decreases with the turbulent intensity due to the dilution of gas-phase volatiles by the turbulent eddies motion. Volatile flame has higher local luminosity and peak combustion temperature at a low turbulent fluctuation velocity of 0 ∼ 0.8 m/s but gradually weakens due to heat dissipation at a higher turbulent fluctuation velocity of 0.8 ∼ 1.6 m/s. The present results are the first to study the combustion behaviours of a single biomass pellet in different turbulent intensities, indicating that the effect of enhanced heat and mass transfer in turbulent environments on biomass combustion is essential and deserves further study. [ABSTRACT FROM AUTHOR]