Search

The co-combustion of sorghum straw and paper-making sludge (PMS) is beneficial to alleviate the ash-related problem in sorghum straw combustion process. In this paper, the mineral migration and transformation behavior in sorghum straw ashes with the addition of PMS ashes under an oxidizing atmosphere were investigated using an X-ray diffractometer, thermogravimetric-derivative thermogravimetric, scanning electron microscopy-energy dispersive X-ray detector, and FactSage software. The results demonstrated that the increase in the PMS ash mass ratio led to an increase in ash fusion temperature (AFT) of sorghum straw mixtures. The generations of high melting-point (MP) calcium feldspar (e.g., Ca 2 MgSi 2 O 7 , Ca 2 Al 2 SiO 7 , Ca 3 MgSi 2 O 8 , and Ca 7 Mg (SiO 4) 4) and phosphates (e.g., Ca 3 P 2 O 8 , Ca 5 P 2 SiO 12 , and Ca 7 P 2 Si 2 O 16) caused the increases in the AFT. The maximum weight loss of sorghum straw ashes decreased with the increasing PMS ash mass ratio, and the surface of the ashes underwent the transition from smooth to a whole loose and rough, which alleviated the ash-related problems of sorghum straw. The addition of PMS ashes decreasing the liquid-phase content calculated by FactSage at the same temperature also explained the sorghum straw AFT increase. The changes of AFT and its corresponding mechanisms in the sorghum straw with PMS ash addition under an oxidizing atmosphere provided the support for large-scale combustion of biomass. • Sludge addition increased the ash fusion temperature (AFT) of sorghum straw. • Calcium containing minerals were formed due to the addition of paper-making sludge. • Ca 3 MgSi 2 O 8 , Ca 2 MgSi 2 O 7 , and Ca 2 Al 2 SiO 7 were generated caused AFT increase. • The transformation of calcium phosphates content increased with increasing temperature. • Thermogravimetric analysis of ash samples illustrated the mineral interaction. [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]

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 paper characterizes waste in the form of fly ash generated in a power plant during the combustion of biomass in a fluidized bed in terms of its possible use in the ceramic building materials industry. This is important from the point of view of environmental protection. In order to assess the possibility of using ash in the production of red ceramics (e.g. bricks), two different clay raw materials (Clay I and Clay II) were selected to prepare the raw material sets. First of all, the investigated fly ash was subjected to thermogravimetric TG-DTG analysis and its basic chemical composition was determined. Then the specific density was determined for all the raw materials, XRD analysis was also performed and finally characteristic temperatures were determined by means of a high-temperature microscope. The basic raw material sets included clayey raw material and fly ash in various contents: 5 wt%, 10 wt% and 15 wt%. Samples were pressed from the ready sets and fired at the temperature of 1000℃. Afterwards, the obtained samples were subjected to XRD and microstructural tests, then selected physical properties were determined, i.e. water absorption, porosity, apparent density, and compressive strength. Based on the research and analysis of the results, it was found that the introduction of fly ash from biomass combustion into the raw material set in the range of 5–15 wt% has a positive effect on the insulating properties of red ceramics. In addition, the density of the red ceramics decreases with the increase in the addition of fly ash, while its porosity and water absorption increase. Furthermore, the addition of fly ash decreases the compressive strength and visually brightens the microstructure of the products. • It is possible to use fly ash from combustion in the production of red ceramics. • The sintering process transforms dusty waste into a harmless product. • The addition of ashes to clay reduces the density of finished products. • Products with the addition of fly ash have higher porosity. • Ceramic products with the addition of ashes are full-value products. [ABSTRACT FROM AUTHOR]

It is of great significance for cleaner production to partially replace traditional coke with biomass fuel in iron ore sintering processes. However, the higher reactivity of biomass leads to an unacceptable deterioration in sintering performance, which limits its high proportion application. This paper presents the numerical simulation of the technology of combining gaseous fuels and biomass for iron ore sintering. The improvement effect and mechanism of the methane injection method on the heat pattern and performance of the coke/biochar co-sintering bed were discussed. To more accurately quantify the coupling phenomena involved, the proposed model especially considers sub-processes of biomass combustion and gaseous reactions including volatile release/char formation, burning of the volatiles, and the oxidation and gasification of char particles. The results indicated that the equivalent methane heat injection method reached its limit of improvement at a concentration of about 0.6%, and failed to obtain qualified products. The thermal indicators and yield kept increasing within the concentration simulation range of 0∼0.8% under the extra methane method. At a concentration of 0.8%, peak temperature (PT), duration time (DTMZ), and enclosed area (MQI) in the high-temperature zone are 1442.094 K, 165.6 s, and 15923.72 K s, respectively, reaching the level of all coke method. The use of local concentration segregation can significantly optimize heat distribution and increase the yield of the coke/biochar co-sintering process. • A numerical model for combining gaseous fuel and biomass in sintering is proposed. • Extra methane injection has no improvement limit within concentrations 0.1%–0.8%. • Gaseous fuel combustion zone makes the melting zone enlarge. • Coke/biochar co-combustion is helpful in attaching the secondary combustion zone. • Methane injection makes 60% biochar sintering reach the level of all coke method. [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]

In this paper, one-dimensional intra-pellet solid model combined with multi-dimensional extra-pellet environment model were used to simulate the combustion processes of a biomass pellet in a furnace. The combustion processes of the solid phase were calculated using a self-written MATLAB code, and the processes of the extra-pellet fluid environment were calculated using the commercial CFD code. The two codes were coupled together by exchanging the data of source terms and boundary conditions in real-time. Experiments on combustion of a single corn-stover pellet in a tube furnace were implemented to validate the calculation method and acceptable agreements were obtained, and the main errors are within 10%. The heterogeneous-dimension discretization method made the updating and debugging of the physical and chemical mechanism of the solid phase very easy. Compared with constant environment conditions, the average error of coupling calculation method is decreased by about 5%. The calculation method can be extended to deal with many other problems. • One-dimensional discretization of pellet was coupled with multi-dimensional discretization of environment. • Self-written MATLAB code was coupled with Fluent and data exchanges between two software in real-time were realized. • Compared with constant-conditions, the average relative error of coupled calculation method is decreased by about 5%. [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]

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]

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]

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]

In this paper, the online light scattering method, combined with the offline thermophoretic sampling particle diagnostic method, was used to measure the formation and evolution of soot during coal and biomass combustion along the time and axial. A light scattering measurement system that can accurately move vertically was constructed to measure the light scattering intensity along axial. The particle size distribution was obtained by the thermophoretic sampling particle diagnostic method. The results show that the scattered light intensity of sesame stalk flame is divided into three stages over time, namely the slow rising zone (zone I), the rapid rising zone (zone II), and the rapid decreasing zone (zone Ⅲ). The rising zone of sesame stalk is long and the decreasing zone is extremely short. The scattered light intensity of Shenhua coal flame is divided into two stages over time, namely the rising zone (zone I) and the decreasing zone (zone II). The rising zone and the decreasing zone of Shenhua coal are almost symmetrical. When the flame burns stably, a large amount of soot is formed at the height of H = 10 mm, and the soot mass of Shenhua coal is about twice that of sesame stalk, which is mainly due to the large difference in volatile components between the two. As the flame height rises, the soot mass drops rapidly at H = 10–30 mm. In the range of 10–20 mm, the soot mass has been decreased by 76.07% for Shenhua coal, and 51.71% for sesame stalk. When H > 30 mm, the soot mass of sesame stalk and Shenhua coal slowly decreases. It is due to the change in the total surface area of soot particles during the combustion process. [Display omitted] • A light scattering measurement system that can accurately move vertically is constructed for the flames. • The distribution of soot particles over time and space during solid fuel combustion was explored. • When the flame is stable, the mass of soot decreases with increasing height. [ABSTRACT FROM AUTHOR]

Grate-fired boiler is of considerable interest for burning biomass owing to its reduced sensitivity to variations in fuel composition and size. However, grate-fired technology exhibits unsatisfactory performance in terms of combustion efficiency, contaminant emissions, and flame stability. CFD modelling can provide reasonable optimizations to overcome these drawbacks and ultimately achieve clean and efficient energy production. Conventional approach simulates the fuel-bed and freeboard combustion separately using an in- and over-bed coupling procedure, where data of the gases leaving from the packed-bed top and the radiative heat flux emitted by the high-temperature flame onto the bed cannot be interacted in real-time. This may cause distinct deviations in the calculations. In this paper, a three-dimensional (3D) full-scale integrated model is developed for the simulation of grate-fired boiler, in which the intensive combustion of both the freeboard and fuel-bed is solved in one scheme using the Eulerian-Lagrangian method. The gas phase is considered as a continuous medium and calculated by the Eulerian model, while the solid particles are considered as a discrete phase and tracked via the Lagrangian method. The reliability of the model is well verified through various field measurements and observations. Results shows that the key parameters are non-uniformly distributed along the grate width, i.e., the aerodynamic and combustion environment is poor at the vicinity of water-cooled walls compared with that at the furnace center. This results in a significant lag in volatile gases release and char oxidation near the water-cooled wall on both sides, which finally causes obvious differences in the distribution of temperature and species. For instance, the peak of CO concentration at the center is 12.6 % at 3.3m from the feed entrance, while that near the water-cooled wall is 8.6 % around 3.5m. The char burnout ratio in the bottom ash can be accurately calculated by this model, with a negligible relative error between the simulation of 81.97 % and the measurement of 82.50 %. It also provides a novel method for the calculation of fly ash particles by using size-grouped and non-spherical particles. Small-size particles in the vicinity of the feed inlet, as well as a part of the particles burning at the end of the grate are entrained into the freeboard by the primary air supplied beneath the grate and the high-momentum secondary air on the bed top. This model can provide valuable theoretical guidance for optimizing the refined distribution of fuel and air in grate-fired power plants and mitigating irregular deposition (corrosion) on heat exchangers and water-cooled walls caused by fly ash. [Display omitted] • An integrated model is developed for accurate modeling of travelling grate boiler. • Real-time mass and heat transfer between the fuel bed and freeboard is achieved. • Key parameters are found to be non-uniformly distributed along the grate width. • Non-spherical and size-grouped particles are used to better represent agricultural straw. • A novel method for calculating fly ash in grate-fired boiler has been developed. [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]

Ignition behaviour of biomass is an essential knowledge for plant design and process control of biomass combustion. Understanding of ignition characteristics of its main chemical components, i.e. cellulose, hemicellulose, lignin and their mixtures will allow the further investigation of ignition behaviour of a wider range of biomass feedstock. This paper experimentally investigates the influences of interactions among cellulose, hemicellulose and lignin on the ignition behaviour of biomass by thermogravimetric analysis. Thermal properties of an artificial biomass, consisting of a mixture of the three components will be studied and compared to that of natural biomass in atmospheres of air and nitrogen in terms of their ignition behaviour. The results showed that the identified ignition temperatures of cellulose, hemicellulose and lignin are 410 °C, 370 °C and 405 °C, respectively. It has been found that the influence of their interactions on the ignition behaviour of mixtures is insignificant, indicating that the ignition behaviour of various biomass feedstock could be predicted with high accuracy if the mass fractions of cellulose, hemicellulose and lignin are known. While the deficiencies of the determined mutual interactions would be further improved by the analytical results of the activation energies of cellulose, hemicellulose, lignin, their mixtures as well as natural and artificial biomass in air conditions. • First research on biomass ignition through its chemical compounds was conducted. • Ignition temperatures of cellulose, hemicellulose and lignin were determined. • The effects of interaction of biomass compounds on its ignition were negligible. • Ignition temperature of biomass is predictable via its chemical compounds. [ABSTRACT FROM AUTHOR]

The paper presents results of experimental investigation performed in order to examine kinetics of loose biomass combustion in vertical tube reactor. The investigation conducted included continuous measurement of the fuel mass loss rate, with two biomass combustion models (piston and batch model) proposed, each relying on appropriate theoretical postulates. Results obtained indicated that piston combustion model had shown better agreement between theoretical and experimental data and was therefore used to further analyse effects of excess-air on the combustion kinetics, as well as associated effects of flue gas recirculation. Recirculation of cold flue gases is used to lower peak temperature inside the furnace, as well as to reduce a zone where ash melting problems may potentially occur. During the investigation performed, effects of flue gas recirculation on the combustion process were simulated by simultaneously injecting nitrogen and air flows into the furnace. This was deemed appropriate to simulate real-life conditions prevailing in the furnace with gas recirculation. Experiments were conducted on specially designed and constructed apparatus that enabled kinetic parameters to be determined for the combustion of different types of biomass. Results obtained have indicated that quantity of air affects kinetics of biomass combustion and that increased recirculation leads to reduced biomass reaction rate. The same conclusion was reached based on the results of experiments conducted with two different types of agro-biomass, namely wheat straw and corn stalks, which are most commonly used for energy generation. Results achieved are deemed particularly important when it comes to design of new plants that utilize cigarette type combustion system, but also for development of numerical models used to simulate combustion of biomass bales, with special emphasis placed on the impact of recirculation gases on the combustion kinetics. • Experimental investigation performed in order to examine kinetics of biomass combustion in vertical tube reactor. • The piston and batch combustion models were used to analyze biomass combustion kinetics in vertical tube reactor. • The piston combustion model provides better agreement with experimental data. • Experimental results have confirmed that the increase in excess air and air velocity leads to reaction rates increasing. • Experimental investigation has also addressed the impact of flue gas recirculation on the fuel reaction rate. [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]

This paper examines the extent and intensity of energy poverty among households in the Kasargod district of Kerala. The inspiration to focus the study on Kasargod district is its socio-economic backwardness relative to Kerala as a whole. Household survey was conducted with a pre-designed questionnaire, and energy poverty was examined using multidimensional energy poverty index (MEPI). Results indicate that, although almost all households are electrified, households face intermittent power outages, and hence they are forced to rely upon alternative measures like power backup facilities. Although most households have access to clean cooking, they also use biomass like firewood extensively and hence widespread practice of fuel-wood stacking is reported. Since households use traditional stoves without chimney to burn fuel-wood, the very purpose of promoting clean cooking to eliminate health hazards of burning biomass is defeated. Overall, the results indicate that effective tackling of energy poverty and resultant evils requires not only economic security but also the capacity to influence the habits and customs of the people. • Although Kerala is fully electrified state, Kasargod region exhibits instances of intermittent supply of electricity, • Evidence of fuel stacking due to easy availability of fuel wood • Women in energy poor household are burdened with the collection of fuel wood leading to capability deprivation. • Incidence of energy poverty across socio-economic categories [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]

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]

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]

Frequent forest fires severely damage forest ecosystems. One potential big issue, however, is the fact that the substantial release of greenhouse gases (GHGs) from biomass combustion significantly impacts the global climate system and carbon balance. This study aims to assess the emissions of major carbon-containing gases from forest fires in mainland China between 2011 and 2021. Information on wildfires was obtained with Google Earth Engine (GEE) through the integration of MODIS products and Global Forest Above Ground Biomass (AGB) produced by the Climate Change Initiative Biomass (CCI BIOMASS) Programme. Utilizing the combustible load model and consideration of carbon emission factors in different vegetation, from 2011 to 2022, mainland China consumed an estimated 35.55 Tg C (3.23 Tg C yr−1) of above-ground combustible matter, resulting in 46.94 Tg (4.27 Tg yr−1) of carbon-containing gas emissions. Among these emissions, 42.16 Tg (3.83 Tg yr−1), 4.58 Tg (0.42 Tg yr−1), and 0.20 Tg (0.02 Tg yr−1) were attributed to CO 2 , CO, and CH 4. In general, carbon emissions from forest fires in mainland China exhibited a declining pattern with fluctuations. This indicates a substantial decrease in average annual emissions of CO 2 and CH 4 by 48.38% and 88.87%, respectively, compared to the previous century (1990s). Additionally, there was an average annual decrease in biomass consumption of approximately 35.4%. When analyzing the results on regional scales using linear regression and normalization methods, it was found that 81%–84% of provinces and regions in mainland China showed a decline in forest fire carbon emissions. Nevertheless, several areas in the northwest region displayed a noticeable rising trend. Pixel analysis is utilized in this paper to perform a spatial analysis of carbon emissions and fire locations associated with forestry fires in mainland China. This analysis clarifies the impact of combustible load distribution across different fire intensities on the interannual variability of carbon emissions from wildfires, thereby offering fire management authorities valuable insights. • Estimated carbon-containing gas emissions from wildfires in Mainland China at a pixel level in 2011–2021. • Compared 11-year average annual wildfire emissions with data from the previous century. • Explored the interrelationships among wildfire points, burnt area, net primary productivity, and fuel load. • Analyzed emission trends of major carbon gases from wildfires in Mainland China. [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, a system for energy production from biomass combustion to provide electricity to the national grid of Vietnam was evaluated based on different thermodynamics systems and the cultivation capacity of the local area. A 20:80 mixture of cashew shell and cashew wood chip is considered as fuel source to be combusted utilizing a fixed bed technology with high energy efficiency. Considering a 10 MW production capacity to the national grid, a 20-year Net Present Value analysis and payback time evaluation was considered based on the economic factors in Vietnam. The study demonstrates how the current feed-in tariff in Vietnam is too low to encourage investment in biomass power plant. Following a suggested electricity selling price that is close to the household electric cost, the power plant shows high potential with a short payback period of 9.22 years and a levelized cost of electricity (LCOE) of only 6.4 cents/kWh. Sensitivity analyses were performed for different scenarios of material cost, electricity selling price and initial investment to show that within a 10 % variation in process factors, such project would still be able to reach payback within 20 years, with an overall LCOE of around 5–7 cents/kWh, proving the high potential of biomass-based energy production projects. • An unprecedented cashew nutshell and woodchip fuel blend is used for practicality. • On-site biomass collection and analysis were performed for accurate assessment. • FiT should be adjusted to around the household electric price to achieve payback. • An LCOE of only 6.3 cents/kWh can be attained after a 20-year lifetime. • A 10 % reduction in electricity price can increase 4 years to the payback period. [ABSTRACT FROM AUTHOR]

In this paper, the volatile and char combustion were separated in a high temperature fixed bed reactor. The effects of temperature (700–1300 °C) and oxygen concentration (5%–40%) on volatile-N and char-N, as well as the nitrogen conversion mechanism of three different biomass were studied in O 2 /CO 2 and O 2 /Ar atmospheres. The results show that the release amount of fuel-NO increases first and then decreases with temperature in both coupled and separated combustion. Nitrogen redistribution caused by the interaction between volatile and char during pyrolysis at high temperatures can affect the final release amount of fuel-NO. Thus, below 1100 °C, the release amount of fuel-NO in coupled combustion is smaller than that in separated combustion, while the opposite trend is shown after 1100 °C. With temperature increasing, the release amount of volatile-NO increases first and then decreases, while the release amount of char-NO decreases continuously. The release amount of volatile-NO in O 2 /CO 2 is less than that in O 2 /Ar, and the release amount of char-NO also shows the same result at low temperature, and shows the opposite trend at high temperature. With oxygen concentration increasing, the release amount of fuel-NO in coupled and separated combustion, as well as volatile-NO and char-NO increases first and then decreases. • Separated and coupled combustion of biomass were carried out in O 2 /CO 2 and O 2 /Ar atmospheres. • The contribution of volatile-N and char-N to fuel-NO was studied by separated combustion. • The variation trend of volatile-NO and char-NO with temperature was obtained. • Fuel-N redistribution in devolatilization is more significant above 1100 °C. [ABSTRACT FROM AUTHOR]

Co-firing with coal is a promising technology for alleviating the ash-related issues during biomass combustion. This paper examines the effects of co-firing coal and straw on deposition characteristics under various biomass fractions and illustrates the mechanism of deposition formation during co-firing. Deposition experiments were conducted on a drop tube furnace with an air-cooled probe simulating the surface of the superheater. To clarify the detailed formation process of deposition, the micromorphology of deposits collected at different depths along the perpendicular direction to the deposition probe, as well as the elemental composition and mineralogy were characterized by SEM/EDS, XRF and XRD. Results showed that co-firing with coal reduced the serious slagging observed during biomass combustion, whereas resulted in higher deposition efficiency than that occurred in unblended coal/biomass combustion. As biomass fractions increased, the deposition efficiency exhibited a non-monotonic downward trend, whereas the sintering degree intensified remarkably. The formation of Ca sulfates and Fe-AAEMs aluminosilicates during co-firing led to the enrichment of Ca, S, Al, and Fe in deposits, and thus promoted melt-induced agglomeration. Viscous particles and adhesive films rich in alkali sulfates adhered closely to the probe surface were believed to be the initial layer, which triggered the deposition formation during co-firing. The inner layer composed of low-melting particles accelerated the formation and growth of deposition. Meanwhile, the fusion characteristics of coarse particles in the outer layer dominated the sintering degree. Co-firing with coal greatly alleviated the slagging tendency compared with biomass combustion, but we should be aware of the negative glue effect of AAEMs sulfates. [Display omitted] • Clarify the mechanism of deposition formation during co-firing wheat straw with coal. • Ca and K sulfates produced during co-firing significantly promoted agglomeration. • The initial layer composed of viscous particles and films triggered the deposition. • The inner layer rich in low-melting substances accelerated the growth of deposition. • The fusion characteristics of the outer particles dominated the slagging degree. [ABSTRACT FROM AUTHOR]

The reduction of pollutant emissions from internal combustion engines, and in particular greenhouse gases, must be achieved by optimizing the combustion process and choosing fuels with a low carbon impact. Heterogeneous mixture combustions such as Diesel induce a difficulty in managing of the pollutants formation even if in its principle the output efficiency remains favorable. Therefore, it is necessary to distinguish this last point, which refers to the compression ratio, in order to move towards homogeneous combustion with a high compression ratio. We then speak generically of HCCI combustion (Homogeneous Charge Compression Ignition), whose process takes place in the context of auto ignition. An important challenge of this combustion is the control of the ignition timing. This paper presents a concept to control the initiation of combustion of a reactive gas mixture with low susceptibility to auto-ignition, which meets the expectation of high efficiency, via the introduction of biomass particles. From a schematic point of view, these particles will play the role of spark plugs distributed throughout the combustion chamber, and should have an auto ignition time much lower than that of the fuel. For this purpose, a particle injector was conceived to directly inject a controlled quantity of biomass powder into the reactive mixture directly. This part is a challenging point. The reproducibility and viability of the particle injector were qualitatively validated by image analysis acquired at high frequency and high resolution. Thus, the system was integrated into an RCM (Rapid Compression Machine) chamber, allowing diphasic gas/solid biomass combustion study. This preliminary test was investigated by high-speed video on a lean diluted biomass enriched with hydrogen mixture (CH 4 /CO 2 /H 2) at low fuel-air equivalence ratio (Φ = 0.6), with different auto-ignition delays in the condition of experimentation. It was shown that the direct injection of a small amount of biomass particles was able to promote its reactivity and initiate the combustion process. This study highlights the promising effects of the injection of powder to control the beginning of homogeneous combustion, by bringing locally a spot of energy, distributed in the whole chamber. The control given by a global contribution of weak energy is distinguished from the process of combustion by auto-ignition of the fuel mixture whose properties of equivalence air-fuel ratio or dilution will complete the optimization of the process. • Control of lean homogeneous mixture combustion by biomass particles injection in a rapid compression machine. • Alternative renewable fuels using methane and hydrogen for sustainable development. • Auto ignition combustion control, biomass and biogas optimal fuels, greenhouse gas reduction, duals diphasic fuel mode. [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]

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]

Geographers' engagements with environmental crises have taken a number of forms. Some scholars argue that crises judgments are revelatory and expose the contradictions of modes of production through interruptions to socio-economic life that can no longer be ignored. Others contend that crises judgments conceal more than they reveal through the framing of crisis as "error" and the focus on technocratic solutions to political-economic problems. In this article, we argue that the judgment of seasonal air pollution as a crisis is contingent on contestations over livelihoods and worldviews, and in doing so demonstrate how attention to chronopolitics reveals the nuanced ways people account for uncertainty in the causes and effects of anthropogenic environmental change. Based in northern Thailand, the paper focuses on what is described by many residents as the region's annually recurring "haze crisis". In recent decades, broad shifts from subsistence farming to commercial agriculture and increased volumes of agricultural biomass burning have reportedly exacerbated the production of air pollution in the form of haze—an airborne mixture of pollutants that includes gasses, fine soot particles and carbon dioxide. Once a quotidian phenomenon of relatively little concern, today seasonal air pollution is described as a haze crisis. While causal uncertainty exists surrounding the precise combination of the socio-ecological drivers of haze production, multiple narratives circulate throughout the region, in which blame is frequently placed on smallholder farmers who have recently entered into new market relations. Situated within broader regional agrarian transitions, we draw on mixed ethnographic, archival and geospatial methods to examine the chronopolitics of seasonal air pollution and by what mechanisms such pollution comes to be constituted as a crisis. [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]

While the biomass gasification and cofiring technology is promising for future energy, including green technologies, such as carbon capture and storage and bioresource feedstock, negative carbon emissions are simultaneously possible using these technologies. However, despite these functions, our previous study established that for simulating a biomass reactor, a new model needed to be designed that could improve the accuracy of both real and lab-scale simulations for carbonaceous fuels, such as coal-based applications. Hence, in this study, a biomass experiment utilizing a thermogravimetric analyzer was conducted to obtain varying reaction rate data over carbon conversion, which may then be used to simulate the biomass conversion model and 3D simulation was also conducted for a 500 MWe coal-biomass cofiring boiler. Gasification was obtained at 1000 °C and 1200 °C using CO 2 at constant temperature for different biomasses. Compared to the peak exhibited by the random pore model, biomass gasification reaction rates shifted into the later stage of the reaction, thereby yielding irregular reaction rate developments and poor prediction accuracies. With flexibility-enhanced random pore model(FERPM), we observed that correlation factors increased from the previously reported value of 0.7–0.95. In the coal-biomass cofiring boiler, the difference between the Kinetics/Diffusion-limited model and FERPM in biomass combustion aspect was examined, and it was ultimately determined that characteristics of particle reactions through FERPM are valid in 3D analysis. Therefore, this paper proposed a flexibility-enhanced random pore model proven to enhance the prediction accuracy of a simulation. • A biomass reaction development model was established and demonstrated. • The random pore model was modified to produce better prediction accuracy. • A new model was proposed based on the obtained empirical results. • The Numerical simulations of biomass gasification and combustion have been validated. [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]

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]

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]

• 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 smooth combustion process of biomass is of great importance as the world transit away from the use of fossil fuels to embracing environmentally friendly and renewable energy. Ash-related problems, such as slagging, fouling, agglomeration, and corrosion, significantly disrupt the efficient operation of gasification systems, leading to unforeseen breakdowns. Potassium, a prevalent alkali metal in biomass, reacts with chlorine and sulfur in flue gas, generating troublesome compounds. This interaction constitutes the primary source of challenges linked to biomass combustion processes. Additives, especially kaolin, an aluminum-silicate, proved most effective in capturing potassium during combustion, forming high-melting-point potassium aluminum silicate compounds. Hence, this paper provides a summary of issues related to biomass ash, explores the deposition mechanism, outlines methods to mitigate problems associated with ash, and concludes by introducing alum sludge as an outlook. [Display omitted] • Potassium in biomass set in motion ash deposition during combustion. • Biomass ash related problem include slagging and fouling, bed agglomeration and corrosion. • The use of additives, co-combustion and leaching are biomass ash deposition remedy. • Suggestion of waste sludge as an economical alternative solution for biomass ash deposition. [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]

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]

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]

Biomass fuel is an environmentally friendly renewable energy source and carbon-neutral (non-fossil) fuel alternative. To facilitate its wider uptake, significant efforts are undertaken to model and experimentally study biomass combustion processes, in both industrial-scale (grate fired) and small-scale (lab-scale) combustors. In many studies, the core aim is to better understand the relationship between thermal conversion processes (drying, pyrolysis, char conversion) and their interrelationship to combustor performance (efficiency, emissions, process temperatures, scale formation, and instabilities). However, due to the complexity of solid fuel (particle) conversion and fuel bed behaviour, precise modelling of all aspects of biomass fixed-bed combustion is not readily achievable. Despite the existence of excellent experimental and modelling studies on numerous aspects related to the characteristics of forestry derived biomass fuels and their combustion, research in this field is challenging. Complications arise from the multitude of fuels used, the varying geometries and combustor configurations investigated and the different modelling methodologies adopted to resolve steady-state and transient operation. The literature includes works on various aspects of biomass combustion, including that undertaken in fixed-beds. However, whilst these works are valuable, they do not sufficiently cover the methods and fundamentals to model direct thermal conversion, at the bed and particle-level. The aims of the present study are to provide a fundamental overview of the methodologies employed in the modelling of laboratory-scale fixed-bed combustors. The paper also includes treatment of the fundamental thermo-physical fuel characteristics which need to be considered when undertaking macro-scale (bed-level) modelling. The paper concludes with summary observations in relation to the modelling of fixed-bed combustion as well as some opportunities which warrant further research and the challenges to be overcome. [ABSTRACT FROM AUTHOR]

As second part of an extensive study on the relation of co-combustion of biomass and fly ash quality, co-combustion fly ashes were investigated from full-scale co-combustion experiments in the Netherlands using agricultural biomass, meat and bone meal, paper sludge and municipal sewage sludge as secondary fuel. The fly ash was investigated in relation to its performance for use in concrete. It was shown that the quality of co-combustion fly ash can be explained from the characteristics of the fuel and the combustion process. Further, it was shown that also fly ash obtained from high co-combustion percentages is able to meet the basic requirements of the European standard for fly ash in concrete (EN 450). Whether an individual co-combustion fly ash does so, depends on the nature of the co-fired fuel and especially on the amount and nature of its inorganic matter. [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]

[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]