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This work employs a combination of density functional theory-infrared (IR), conductor-like screening model for real solvents (COSMO-RS), and molecular dynamic (MD) methods to investigate the impact of hydroxyl functional groups on CO2 capture within dicationic ionic liquids (DILs). The COSMO-RS reveals that hydroxyl groups in DILs reduce the macroscopic solubility of CO2 but improve the selectivity of CO2 over CO, H2, and CH4 gases. Quantum methods in the gas phase and MD simulations in the liquid phase were conducted to delve deeper into the underlying mechanisms. The IR spectrum analysis confirms red shifts in CO2's asymmetric stretching mode and blue shifts in the CR–HR bond of the dication, indicating CO2–DIL interactions and the weakening of the anion–cation interactions caused by the presence of CO2. The results show that the positioning of anions around hydroxyl groups and HR atoms in rings inhibits the proximity of CO2 molecules, causing the hydrogen atoms within methylene groups to accumulate CO2. van der Waals forces were found to dominate the interaction between ions and CO2. The addition of hydroxyl groups strengthens the electrostatic interactions and hydrogen bonds between dications and anions. The stronger interaction energy between ions in [C5(mim)2-(C2)2(OH)2][NTf2]2 limits the displacement of CO2 molecules within this DIL compared to [C5(mim)2-(C4)2][NTf2]2. Compared to [C5(mim)2-(C4)2][NTf2]2, [C5(mim)2-(C2)2(OH)2][NTf2]2 exhibits stronger ion–ion interactions, higher density, and reduced free volume, resulting in a reduction in CO2 capture. These results provide significant insights into the intermolecular interactions and vibrational properties of CO2 in DIL complexes, emphasizing their significance in developing efficient and sustainable strategies for CO2 capture. [ABSTRACT FROM AUTHOR]

Developing fuels without carbon, such as ammonia (NH 3), is crucial for achieving carbon reduction. Laminar burning velocity (LBV) is investigated, and distribution characteristics of OH and NH radicals are identified through planar laser-induced fluorescence. Rate of production of main free radicals and sensitivity analysis are also studied. The addition of NH 3 to CH 4 -air mixtures results in a decrease in the LBV, a rise in preheating zone height, a reduction in OH radical fluorescence intensity, and an enhancement in NH radical fluorescence intensity. Simulation reveals that the high NH 3 ratio enhance the negative impact of nitrogen-containing elementary reactions on LBV. The addition of NH 3 enhances the initial consumption of more OH via reaction R 248 : NH 2 + OH = NH + H 2 O , leading to increased NH production, and indicating a negative effect on LBV. The decrease in OH concentration is the main factor leading to a decrease in LBV. The reactions affecting the OH generation and consumption are R 39 : H + O 2 = O + OH and R 85 : OH + H 2 = H + H 2 O , respectively. The addition of NH 3 leads to a more significant reduction in R39. • The impact of NH 3 on the combustion characteristics of coal volatiles was studied. • The addition of NH 3 reduces the OH signal while increases the NH signal. • Primary reactions affecting LBV are H + O 2 = O + OH and H + CH 3 (+M) = CH 4 (+M). • H + O 2 = O + OH and OH + H 2 = H + H 2 O are the main reactions for OH generation and consumption. [ABSTRACT FROM AUTHOR]

The paper presents experimental studies on the effect of co-combustion of aviation kerosene with hydrogen in the GTM400 turbojet engine on the change in the carbon footprint generated by the engine in relation to its standard operation without hydrogen in the fuel. This research is in line with current research and development trends carried out in the EU, linking them to the issues of the European Green Deal, the Fit for 55 directive and current environmental trends in aviation and energy. The main objective of the research was to check the effect of hydrogen co-combustion in a turbojet engine on the change of the carbon footprint, while a secondary objective was to verify the impact of higher exhaust gas temperatures generated by the new, high-calorific fuel on the secondary generation of nitrogen oxides (NOx), especially in the thermal mechanism, as an undesirable effect. The research shows that the co-combustion of hydrogen with aviation kerosene in a turbojet engine reduces the carbon footprint (reduction of CO2 maximum of 15% and CO emissions maximum of 24%), but also increases the emission of nitrogen oxides (NOx) maximum of 58%, including those generated in the thermal mechanism (significant increase in the temperature of exhaust gases), moreover, the increase in nitrogen oxide emissions is proportional to the amount of co-combusted hydrogen, which is directly related to the stoichiometry of the combustion process. The main conclusion of the research is that technologies for the combustion or co-combustion of hydrogen in turbojet engines require further research and development, mainly on the side of the use of excess exhaust gas temperature generated during combustion and methods of reducing secondary nitrogen oxides. [ABSTRACT FROM AUTHOR]

When semi-coke is co-combusted with bituminous coal with higher sulfur content in a circulating fluidized bed (CFB) boiler, the necessity of desulfurization in furnace increases. Meanwhile, limestone, which is a widely used desulfurizing agent, also has an effect on NO emission. In order to explore its effect during co-combustion, the combustion experiments were conducted in both a CFB test rig and a fixed bed reactor. The results show that blending semi-coke with bituminous coal will change the occurrence forms of nitrogen in the fuel and more fuel NO is released during the devolatilization stage. During the desulfurization process, CaO will be generated through the calcination reaction. It has catalytic effects on both the oxidation and reduction reactions of NO, and the catalytic strength in these two types of reactions decides the final effect on NO emission. For the blended fuel with 50% semi-coke and 50% bituminous coal (SC50BC50), the NO emission initially increases and then decreases as the Ca/S molar ratio increases from 0 to 4 at 900°C. Compared to the situation of burning semi-coke alone, semi-coke in the blended fuel has more opportunities to contact with CaO under the same Ca/S molar ratio, leading to the heterogeneous reduction reaction of NO enhanced. As the combustion temperature increases from 800°C to 1000°C, the effect of limestone on NO emission will change from promotion to inhibition. This is because the higher combustion temperature can intensify not only the catalytic reduction of NO precursors in the dense-phase region, but also the reaction between NO and unburnt char in the dilute-phase region in the CFB. Besides, the lower O2 concentration in the atmosphere is also favorable for enhancing the catalytic effect of CaO on the NO-char reduction reaction for semi-coke and SC50BC50, so the conversion of fuel-N/NO will be inhibited compared with the cases without limestone. The achievements of this study are beneficial for the coordinated control of NOx and SO2 during the co-combustion of semi-coke and bituminous coal. [ABSTRACT FROM AUTHOR]

Implementing a co-combustion technology in coal-fired plants using biomass waste is a promising option to alleviate environmental pollution, reduce fuel costs, and minimize waste. The considerable potential of palm oil waste is believed to be able to substitute coal as a raw material in a coal-fired power plant. However, since each coal has different compositions and biomass generally has a high alkali content, the propensity of slagging and fouling during co-combustion needs to be clarified. This research evaluates the co-combustion ash characteristics of different types of coal, which is co-combusted with 25% palm oil biomass waste. The combustion test employs a drop tube furnace, where the produced ash composition and its morphology are investigated using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction. The results show that the ash melting temperature of the three types of coal mixed with biomass is reduced, although insignificant. Bituminous coal has a low potential for slagging and fouling since SiO2 and Al2O3 dominate the coal ash composition. In addition, lignite coal has low SiO2 and Al2O3 contents but high alkali contents (K and Na). As confirmed by SEM-EDS analysis, probe observations also show that lignite coal co-combustion with empty fruit bunch and frond waste has higher slagging and fouling risks. [ABSTRACT FROM AUTHOR]

Carbon capture and storage can reduce the carbon emission directly and effectively. Absorption carbon capture (ACC) is currently the most promising way to remove CO2 from coal-fired power plant, yet the main drawback is the excessive thermal energy consumption for the regeneration process. In this study, a new ACC system that utilizing the low-grade waste heat to generate steam has been proposed, in which system the steam is compressed to increase the saturation temperature to satisfy the thermal energy grade demand of the absorbent regeneration. Heat pump is introduced to increase the inlet pressure and enhance the energy and economic effect of vapor compression and R245fa is found suitable for the system. The vapor generating work can be controlled below 200 kWh t−1 when Twh is higher than 60°C, and COPvg can be higher than 3.5 for situations of Ttag,sat not exceeding 130°C. The energy performance and economic analysis of the proposed ACC system driven by the new vapor generation method is analyzed. Off-peak operation by ASS shows good economic effect, the operating cost for the regeneration process of carbon capture is only 69.70 CNY t−1 CO2 under the worst condition and far below the traditional heating method. The new heat supply method for carbon capture presents reasonable energy and economic performance, which is shown suitable for peak shifting of the power grid. [ABSTRACT FROM AUTHOR]

Neural circuits supporting innate behaviors, such as feeding, exploration, and social interaction, intermingle in the lateral hypothalamus (LH). Although previous studies have shown that individual LH neurons change their firing relative to the baseline during one or more behaviors, the firing rate dynamics of LH populations within behavioral episodes and the coordination of behavior-related LH populations remain largely unknown. Here, using unsupervised graph-based clustering of LH neurons firing rate dynamics in freely behaving male mice, we identified distinct populations of cells whose activity corresponds to feeding, specific times during feeding bouts, or other innate behaviors--social interaction and novel object exploration. Feeding-related cells fired together with a higher probability during slow and fast gamma oscillations (30-60 and 60-90 Hz) than during nonrhythmic epochs. In contrast, the cofiring of neurons signaling other behaviors than feeding was overall similar between slow gamma and nonrhythmic epochs but increased during fast gamma oscillations. These results reveal a neural organization of ethological hierarchies in the LH and point to behavior-specific motivational systems, the dysfunction of which may contribute to mental disorders. [ABSTRACT FROM AUTHOR]

In this study, the combined combustion characteristics and gaseous product emissions of coal slime and corn stover were compared at different blending ratios. The TG-DTG curves indicate that the optimal performance is achieved when the corn straw blending ratio is 20%. Furthermore, the TG-FTIR coupling results demonstrated an increase in gas species as the blending ratio increased. The composition analysis of ash samples formed at various combustion temperatures using XRD and XRF indicated that a portion of KCl in the fuel was released as volatile matter, while another part reacted with Al2O3 and SiO2 components in the slime to form silica–aluminate compounds and other substances. Notably, interactions between the components of slime and potassium elements in corn stover primarily occurred within the temperature range of 800–1000 °C. These findings contribute to a comprehensive understanding of biomass and coal co-firing combustion chemistry, offering potential applications for enhancing energy efficiency and reducing emissions in industrial processes. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3), as an ideal zero-carbon fuel, plays a positive role in mitigating global warming. By cofiring NH 3 with highly reactive small molecule fuels such as hydrogen (H 2), carbon monoxide (CO) and methane (CH 4), the reactivity of NH 3 combustion can be significantly enhanced. In this work, a detailed kinetic mechanism for NH 3 /CH 4 /H 2 /CO containing 146 species and 1099 reactions was developed and extensively validated with selected experimental data from the literature on laminar burning velocity (LBV), ignition delay time (IDT), and species concentrations measured in burner-stabilized flames (BSF), plug flow reactors (PFR) and jet-stirred reactors (JSR), covering temperatures of 273–2000 K, pressures of 0.053–40 atm and equivalence ratios of 0.1–2. In addition, the detailed mechanism was simplified to include 53 species and 353 reactions using three simplification methods. Kinetic modeling analysis showed that the chemical and transport effects of H 2 , CO and CH 4 are the main factors enhancing NH 3 combustion, which rising with the increasing initial temperature and decreasing ammonia blending ratio. Among the four reactants, H 2 is consumed first, followed by CH 4 and NH 3 , with CO reacting last. By modifying the Metghalchi-Kech power law equation, it was found that a clear linear relationship exists between LBV and the sum of the maximum mole fractions of O, H, OH, and NH 2 radicals. [Display omitted] • A kinetic mechanism for NH 3 /CH 4 /H 2 /CO was proposed and simplified. • Validation range includes T 0 of 273–2000 K, P 0 of 0.053–40 atm and Ф of 0.1–2. • Chemical kinetics of LBV for NH 3 /H 2 , NH 3 /CO and NH 3 /CH 4 blends were studied. • The correlation between LBV and free radicals was investigated. [ABSTRACT FROM AUTHOR]

This paper presents the results of analytical studies of the combustion process of semi-coke, cedar sawdust, and their mixtures using the TGA method at three different heating rates with the determination of the main characteristics of heating: the presence of synergetic interaction between the components of the mixture affecting the maximum rate of combustion and kinetic parameters. Calculations of activation energy and pre-exponential multiplier of the Arrhenius equation by the Friedman and Ozawa–Flynn–Wall priori methods for initial combustibles and their mixtures have been carried out. Semi-coke was obtained by thermal treatment of brown coal at 700–900 °C to remove volatile substances, which makes it more environmentally friendly than the original coal. Semi-coke has a higher heat of combustion than biomass, and biomass has a higher reactivity than semi-coke. The combustion process of biomass occurs in a lower temperature range, and adding biomass to semi-coke shifts the combustion process to a lower temperature range than such for biomass. Adding at least 50% of biomass to semi-coke increases the combustion index by at least 1.1 times. Regardless of the heating rate of mixtures, synergetic interaction between the mixture's components increases the maximum combustion rate of coke residue by 20%. [ABSTRACT FROM AUTHOR]

A novel series of (1- x)MgGa 2 O 4 - x BaCu(B 2 O 5) (x = 0.1–0.5) microwave dielectric ceramics were prepared by solid phase method. By adding BaCu(B 2 O 5) additives, the sintering temperature of MgGa 2 O 4 ceramics was reduced from 1410 °C to 925 °C. Through an analysis of the trend in packing fraction and FWHM value of T 2g Raman peak, the underlying influence mechanism of various intrinsic factors on the dielectric loss of ceramic were revealed. And the density, as the external factors, exhibits a positive correlation with the dielectric constant and Q × f value. In addition, the high bond strength of Ga-site reduces lattice distortion and consequently enhances the frequency temperature coefficient. The microwave dielectric properties of (1- x)MgGa 2 O 4 - x BaCu(B 2 O 5) (x = 0.3) are found to be superior at a sintering temperature of 925 °C (ε r = 9.42, Q × f = 35,480 GHz, τ f = −22.7 ppm/°C, at 14 GHz). Moreover, the chemical compatibility of ceramics cofiring with Ag electrode makes them a highly promising substrate for microwave communications. Synopsis : BaCu(B 2 O 5) reduces the sintering temperature of MgGa 2 O 4 from 1410 °C to 925 °C for LTCC application with excellent dielectric properties. [Display omitted] [ABSTRACT FROM AUTHOR]

This study employs a numerical computation model based on a municipal solid waste (MSW) incinerator in Nanning to investigate the impact of different sewage sludge (SS) co-combustion ratios and MSW incinerator temperatures on combustion efficiency. Using the FLUENT simulation method, this study systematically analyzes the distribution characteristics of the temperature field, velocity field, and pollutant concentration field within the furnace under various SS mixing ratios (5%, 7%, 10%, and 15%) and MSW incinerator temperatures (800 K, 1000 K, and 1200 K). The simulation results indicate that the combustion efficiency was optimal at an MSW incinerator temperature of 800 K, where the co-combustion of SS with MSW mixed effectively, leading to a stable and efficient combustion process. Furthermore, an SS co-combustion ratio of 7% was identified as the most effective in maintaining high combustion efficiency. These findings contribute to the optimization of co-combustion strategies for MSW and SS, enhancing both operational efficiency and environmental compliance. [ABSTRACT FROM AUTHOR]

Utilising ammonia, which is one of the most promising carbon-free fuels, comes with the challenge of stable combustion due to its low reactivity. Therefore, advanced strategies are needed, including blending ammonia with highly reactive fuels or implementing innovative combustion techniques. For this reason, the present study proposes an ammonia-methane dual-fuel co-firing combustion mode. The second focus is to analyse the effect of preheating the main swirl air on NO emissions and examine the chemical kinetic reactions. Experimentally, chemiluminescence imaging was conducted to analyse OH* and NH 2 * emissions to evaluate the flame structure and reaction zones. Numerically, simulations were performed using a chemical multi-reactor network model to examine kinetics. By comparing the fully premixed combustion to the dual-flame co-burning mode, the NO emissions decreased by 80% in the latter case at T = 473K and ϕ = 0.6. The NH 3 reaction pathway analysis shows a significantly higher percentage reduction of NO and NH 2 reactions in dual flame mode compared to premixed flames. Preheating the main air impacts NO reactions in the dual flame mode, allowing for lower NO emissions. • Pilot premixed NH 3 jet flame surrounded by swirl CH 4 flame is an alternative fuel injection strategy. • Lower emissions of NO can be attained with dual flame without compromising flame stability. • Higher NO x emissions are attained with increasing temperature for premixed flame. • NH 2 +NO ↔ NNH + OH is strengthened with increasing preheating temperature for dual flame. • Dual-fuel flame with preheating is a viable combustion method to lower NO x emissions. [ABSTRACT FROM AUTHOR]

Sunflower husk (SFH) contributes 45–60% of the total sunflower seed weight and is a by-product of the sunflower oil industry. Among other elements, SFH ash contains K, Na, Ca and Mg. These elements cause rapid growth of ash deposits on convective heating surfaces of the boiler, resulting in reduced efficiency. The aim of this paper is to examine the possibility of producing quality fuel from SFH by its pretreatment with the technique of torrefaction in a fluidized bed in superheated water vapor. Continuous monitoring of the innovative SFH torrefaction process allowed for the determination of optimal process durations. SFH could be converted into a biofuel, having high calorific value and suitable characteristics for co-combustion with coal. Furthermore, the torrefaction in a fluidized bed of superheated water vapor allowed for a 6-fold reduction in the required process duration in comparison with data reported from the literature for the process of torrefaction in a dense bed, along with a 3-fold reduction in the chlorine content in SFH ash. These effects are beneficial to resolve the problem of corrosion on convective heating surfaces of boilers. However, torrefaction in superheated water vapor did not significantly reduce the content of alkaline and alkaline-earth elements in SFH ash. Still, this issue may be alleviated by significantly increasing the duration of SFH pretreatment. [ABSTRACT FROM AUTHOR]

This study investigates the effects of the co-combustion of coal and açai seed in circulating fluidized bed (CFB) boilers, highlighting the increase in thermal efficiency and relevance of a less-polluting source of energy. Using the computer software 1.5D CeSFaMB™® v4.3.0, simulations of the co-combustion process of coal and biomass were carried out in a CFB boiler, obtaining results such as the temperature profile, boiler efficiency and emissions. The work acquired data regarding the equipment in real operational conditions, consisting of the fundamental geometric and operational parameters used in the simulation campaign. The thermal and chemical properties of the fuels were analyzed by carrying out proximate, ultimate, heating value, particle size and specific mass analyses. The model validation was achieved by simulating the boiler in its real operating conditions and comparing the obtained results with the real data; the obtained error was below 10%. Simulations with different fractions of açai seed for energy replacement (10% and 30%) were carried out. As a result, an increase in the average temperature of the bed was observed, highlighting the region immediately above the dense bed. An increase in boiler efficiency was verified from 56% to 85% with 10% açai and to 83% with 30% açai seed. Decreases in SO2 and CO emissions with the insertion of açai were obtained, showing that co-combustion is more complete, while CO2 emissions were increased due to the higher quantity of fuel inserted into the equipment. The fossil CO2 emissions were reduced. [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]

The formation of soot and NOx in ammonia/ethylene flames with varying ammonia ratios was investigated through experimental and numerical analysis. The spatial distribution of the soot volume fraction and NOx concentrations along the flame central line were measured, and the mechanism of soot and NOx formation during ammonia/ethylene co-combustion was analyzed using CHEMKIN 17.0. The experimental results indicated that the soot volume fraction decreases with an increase in ammonia ratio, with the soot peak concentration occurring in the upper region of the flame. The distribution of NOx is complex. In the initial part of the flame, a higher concentration of NOx is generated, and the lower the ammonia ratio, the higher the concentration of NOx. As the combustion process progresses, the concentration of NOx initially decreases and then subsequently increases rapidly, with higher ammonia ratios leading to higher concentrations of NOx. The addition of ammonia results in a decrease in CH3, C2H2, and C3H3, and an increase in CN concentration. This leads to a transformation of carbon atoms within the combustion system, reducing the available carbon for soot formation and suppressing its generation. A higher ammonia ratio increases the likelihood that NH3 will be oxidized to N2, as well as increasing the probability that any generated NO will undergo reduction to N2 through the action of the free radicals NH2 and NH. [ABSTRACT FROM AUTHOR]

The European decarbonization goals and requirement for energy independence are mostly relying on intermittent renewable energy sources for electrification. A numerical model was developed to simulate the operation of a steam generator, allowing a study of the potential impacts of retrofitting existing coal-fired power plants to operate with biomass or coal–biomass mixtures on combustion parameters and CO2 emissions. The results obtained using the operational parameters of the Sines power plant indicate that a mixture of 25% coal and 75% pine sawdust allow operation at λ = 1.8, demonstrating that a small amount of coal allows operation near the coal combustion parameters (λ = 1.9). These conditions have the drawback of a reduction of 8.7% in adiabatic flame temperature but a significant reduction of 57.5% in CO2 emissions, considering the biomass as carbon-neutral. [ABSTRACT FROM AUTHOR]

The simulation for sintering of co-firing double layer compacts and substrate-constrained compacts were obtained by coupled Monte Carlo method and finite element method. In the coupled simulation of a co-firing compacts with different sintering shrinkage curves, the amount of warpage during and after sintering changed significantly. As a result of detailed confirmation of the results, it was found that there was a difference between the porosity obtained by the Monte Carlo method and by finite element method, so the coupled simulation was modified to minimize the porosity difference. As a result of the coupled simulation of constraint sintering, it was not contracted in the surface direction, but only in the thickness direction, and the results were represented in the previous experimental results. We found that coupled simulation can be applied as a tool to design and analyze the sintering behavior of products obtained by co-firing and constrained sintering. [ABSTRACT FROM AUTHOR]

Co-combustion of sludge with coal can effectively improve the ignition and combustion characteristics and promote the harmless and resourceful utilization of sludge. Inorganic or organic chlorine can be introduced into municipal sewage during the disinfection and dehydration. The increased chlorine content in municipal sludge may adversely affect boiler heat exchange surfaces and environmental protection equipment. The influence of operating parameters on ignition, Cl element release, particle size, and element distribution of fly ash was investigated using a thermogravimetric-Fourier Transform Infrared Analyzer and a laboratory-scale bubbling fluidized bed. The results show that the volatile content in the sludge is high, and there are three weight loss peaks in its derivative thermogravimetric (DTG) curves, and the maximum weight loss peak appears in the volatile release and combustion stage. As the sludge blending ratio increases, the ignition and burnout temperatures of the fuel gradually decrease. The emission concentrations of CO, NO and SO2 increase as the sludge blending ratio increases. The higher volatile content in the sludge promotes the production of CO, while weakening the reducing atmosphere in the dense phase, which is not conducive to the reduction of NO. During the combustion process, both thermo-gravimetric and fluidized bed experiments show that more than 85% of the chlorine elements in the fuel are released in form of HCl, and the self-trapping effect of ash on HCl is weak, and most of the Cl elements in the fuel eventually are emitted in the form of gaseous HCl. The average particle size of fly ash gradually decreases as the sludge blending ratio increases, indicating that sludge ash breaks into finer particles at high temperatures. As the sludge blending ratio increases, the contents of K, P, and Fe elements in fly ash increase significantly, with P showing the most notable increase.

Ammonia emerges as a promising substitute for traditional fuels, offering a potential reduction in fossil fuel consumption and the associated emissions. Given its weak reactivity, an effective strategy to harness the potential of ammonia involves cofiring it with methane, to establish a self-sustaining combustion process. The understanding of heat release rate (HRR) in the cofiring process of ammonia and methane is crucial for burner design. This study introduces novel HRR indicators through a machine learning-based approach, focusing on species significantly contributing to HRR. Kinetic analysis is carried out utilizing a one-dimensional freely propagating flame model, applying a mechanism including 59 species and 356 reactions. Domain knowledge-based feature selection narrows down the search space, enhancing computational efficiency during HRR indicator identification. A random forest model is then employed to identify radical/radical combinations and their respective reaction orders, representing HRR optimally based on mean decrease impurity. The proposed HRR markers are [CH 4 ]0·76[OH]1.08, [HCO]0·65[NO]0.24, [CH 3 ]0.65[O]0.63, [NH 2 ][O]0.59, and [NH 3 ]0·93[OH]0.96. The root mean square error for each marker was extracted and compared with literature data, demonstrating higher reliability of the proposed indicators over those previously suggested. Additionally, the paper concludes with a discussion of the feasibility of measuring these markers from an experimental perspective. [Display omitted] • Thorough kinetic analysis of focusing on key HRR contributors. • Pioneering ML for crucial HRR indicator identification in ammonia-methane cofiring. • Domain-based feature selection streamlines HRR marker identification for efficiency. • Proposed 5 HRR markers that are superior in accuracy compared to existing markers. [ABSTRACT FROM AUTHOR]

To limit the negative impact on the environment, increasingly stringent regulations are being introduced regarding the reduction of pollutant emissions. In automotive applications, reciprocating internal combustion engines (ICE) are under immense pressure due to emissions. Society aims to move away from fossil fuels. However, it is acknowledged that ICE will continue to play a significant role in electricity generation systems and certain transportation sectors. To achieve zero emissions or drastically reduce emissions, alternative carbon-free fuels are being pursued. Hydrogen (H 2) is a natural substitute for fossil fuels, and recently, ammonia (NH 3) has been considered an intriguing fuel. Ammonia is easier to transport and store compared to hydrogen. NH 3 is a good hydrogen carrier with significant potential for use in ICE. However, ammonia combustion in such applications exhibits challenges related to its low burning rate. Here, hydrogen emerges as a high reactivity fuel, used as a combustion enhancer for NH 3. Hydrogen-assisted ammonia combustion shows great promise for future of ICE. This paper presents a summary of research findings on the NH 3 /H 2 combustion process in a spark-ignition ICE. Concepts of dual-fuel NH 3 /H 2 engine operation, the influence of fuel proportions on cylinder pressure profiles, heat release, combustion stages, and engine emissions aspects are discussed. The directions of development of SI piston engines powered by NH 3 /H 2 are given. • Assessment of NH 3 and NH 3 /H 2 combustion strategies in the SI engine • Direct injection of ammonia reduces its content in exhaust gases. • SI engine powered by NH 3 requires high ignition energy. • The challenge is to reduce N 2 O emissions. • Hydrogen expands the spectrum of application of NH 3 as a fuel for the SI engine. [ABSTRACT FROM AUTHOR]

In this study, three premixed swirl gas turbine nozzles with different fuel injection hole sizes were designed to optimize combustion characteristics influenced by changes in the hydrogen mixing ratio. Experiments involved increasing the hydrogen volume fraction of the fuel from 0 to 60%. The amount of fuel supplied through the pilot flow was increased to suppress combustion instability. The OH* chemiluminescence technique was introduced to analyze flame structure. To understand combustion instability, time delay and time-delay distribution were derived from flame structure analysis and applied to the 1D thermoacoustic model. The results indicated that the amount of fuel required for pilot injection with increasing hydrogen ratio varied with fuel hole size. It was also observed that changes in fuel hole size significantly affected flame characteristic length. Findings from the 1D thermoacoustic analysis confirmed that fuel hole size variation altered combustion instability characteristics by influencing time delay and time-delay distribution variation. [Display omitted] • This study investigated the impact of fuel hole size for H 2 co-firing. • Increase in H 2 fraction reduced flame length and heat release distribution. • Fuel hole size variation affected time delay and its distribution. • Changing the time delay and its distribution influenced combustion instability. [ABSTRACT FROM AUTHOR]

The coal/ammonia co-firing technology for thermal power generation is a feasible method to effectively reduce CO 2 emissions. However, the easy formation of NO x is one of the challenges faced by this technology owing to the high nitrogen content in ammonia. This study proposes a novel swirl burner with a scalable dual-channel ammonia pipe, and evaluates the combustion and NO x formation under different extension lengths of the dual-channel ammonia pipe (i.e., 0 m, 0.4 m, 0.8 m, 1.0 m, 1.2 m). The results show that the extension length of the dual-channel ammonia pipe significantly affects the flow, combustion, and NO x formation. When the extension length of the dual-channel ammonia pipe is above 0.8 m, the ammonia stream can completely penetrate the internal recirculation zone into the high CO environment, which contributes to promoting the ammonia pyrolysis and inhibiting the ammonia oxidation to form NO x. NO x emissions significantly decrease from 846 ppm to 146 ppm as the extension length of the dual-channel ammonia pipe from 0 m to 0.8 m, but change slightly as further increases from 0.8 m to 1.2 m. The carbon content in fly ash decreases from 4.53% to 3.40% as the extension length of the dual-channel ammonia pipe increases from 0 m to 1.0 m. Still, it increases from 3.40% to 3.70% as the extension length of the dual-channel ammonia pipe rises to 1.2 m. Overall, it is reasonable to set the extension length of the dual-channel ammonia pipe at 1.0 m in this studied condition, which can obtain low NO x and low carbon content in fly ash. [Display omitted] • A novel swirl burner with a scalable dual-channel NH 3 pipe is proposed. • Effect of NH 3 pipe extension length on combustion and NO x formation is investigated. • NH 3 pipe extension length significantly affects flow, combustion, and NO x formation. • 1.0 m for NH 3 pipe extension length is reasonable with good performance. [ABSTRACT FROM AUTHOR]

Ammonia (NH 3) and biomass are recognised as renewable energy carriers with substantial promise for reducing carbon emissions. However, the issue of nitrogen oxides (NO X , including NO and NO 2) and nitrous oxide (N 2 O) emissions from ammonia combustion and soot from biomass combustion, remains a pressing concern due to their detrimental impacts on the environment and human health. This study investigated the mechanism of pollutant formation during ammonia-lignin co-firing through reactive molecular dynamics (RMD) simulations. The results indicate that co-firing a certain amount of ammonia with lignin can reduce the formation of soot. This is mainly due to NH 2 radicals converting a portion of polycyclic aromatic hydrocarbon (PAH) precursors into C–N compounds. However, it is necessary to maintain higher ammonia concentrations. Adding a small quantity of ammonia would decrease the extent of oxidative reactions within the system and fail to generate enough NH 2 radicals to consume the carbon atoms forming PAH precursors, ultimately resulting in increased soot production. The impact of lignin on the formation of NO X and N 2 O during ammonia combustion has two main aspects: Firstly, the oxidising radicals formed during the initial decomposition of lignin promote the generation of N–O bonds, leading to an increase in the quantities of NO X and N 2 O during the initial reaction stage. Secondly, the carbon-containing products produced from lignin decomposition consume nitrogen atoms by forming N–C bonds, thereby diminishing available nitrogen atoms for nitrogen oxides formation. This study provides new insights into the formation of primary pollutants of ammonia and biomass co-firing on an atomic scale, which can help develop pollutant mitigation measures. • The chemical mechanism of pollutant formation during the co-firing of ammonia and biomass lignin is revealed. • A small quantity of ammonia promotes soot formation but increased quantities have the opposite effect. • NO production is enhanced by lignin in the initial stage of the co-firing, but the trend is reversed subsequently. • NO 2 formation is linked to oxidative reactions, while N 2 O formation depends on NH 2 concentration. [ABSTRACT FROM AUTHOR]

A large amount of biomass wastes have been generated during agricultural production nowadays. The combustion and gasification can be expected to convert the biomass into clean energy, such as gas, electricity, and heat. Among them, the characteristic temperature of ash fusion is one of the important indexes for the tendency of slagging. Since the biomass ash is a mixture of a variety of minerals, there is no fixed melting point within a certain temperature range. In general, ash fusion temperatures are commonly characterized by four characteristic temperatures, namely the deformation, softening, hemisphere, and flow temperature. Few studies have been conducted to predict the ash fusion temperature of biomass and coal co-combustion ash. Most of them only considered the role of alkaline components in the ash, particularly without the influence of acidic components (SO3 and P2O5). This investigation aims to fully consider the effects of acidic/alkaline components in ash on the ash fusion temperature. Seven oxides were taken as the variables, including Al2O3, SiO2, P2O5, SO3, K2O, CaO, and Fe2O3 in biomass and coal co-combustion ash. A prediction model was established for the ash fusion temperature of biomass and coal co-combustion ash using a multiple linear regression model in the Matlab software. Besides, taking the corn straw and Shenmu bituminous coal in rural areas of China as examples, the ash composition and ash fusion temperatures were measured under different mixing ratios, temperatures, and residence times. The results showed that the content of MgO, K2O, CaO, Na2O, Fe2O3, and MnO oxides increased with the increase of the content of corn straw from 25% to 75%. Especially for K2O, the content increased from 5.89% to 14.41%. The content of acidic oxides decreased gradually, such as Al2O3, P2O5, and SO3, among which the content of Al2O3 decreased from 12.05% to 7.78%, the content of P2O5 decreased from 3.66% to 1.07%, and the content of SO3 decreased from 7.70% to 1.48%. The Cl content decreased outstandingly with the increase of ashing temperature and the extension of residence time. A comparison was made between the prediction and the experimental values, according to the existing empirical formula. It was found that the influence coefficients of P2O5 and SO3 on the characteristic ash fusion temperature were large in the prediction model, which was consistent with the test. It inferred that there was a significant effect of acidic components, such as P2O5 and SO3, on the ash fusion temperatures. Actually, the ash fusion temperature was positively correlated with the content of oxides, such as Al2O3, SiO2, P2O5, and CaO, indicating a great contribution to the inhibition of ash melting and slagging. There was an error of less than 5% in the characteristic ash fusion temperatures between the prediction of the model and the experiment, indicating the better fitting of the multiple linear regression. The accuracy and reliability of the model were verified as well. [ABSTRACT FROM AUTHOR]

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The co-combustion characteristics and synergy of distillery effluent sludge (DES) and sugar mill waste (SMW) were studied by thermogravimetric (TG) analysis. TG data were used to evaluate the combustion indices, synergy, kinetic parameters, and heterogeneous reaction mechanisms. The blend D1S3 (25% DES and 75% SMW) exhibited optimal combustion parameters (Ci = 2.69 × 10−4% min−3, Cb = 1.34 × 10−6% min−4, and CCI = 13.02 × 10−7%2 °C−3 min−2). Mixing DES with SMW resulted in a positive synergy that facilitated effective combustion owing to the presence of Fe, Ca, and Mg in DES, which served as catalysts during combustion. For D1S3, the apparent activation energy (*Ea) calculated using FWO, KAS, and ST iso-conversional methods were 173.3, 172.4, and 172.7 kJ mol−1, respectively. The master plots revealed that the combustion process was governed by the D1, D3, F2, and F3 solid-state kinetic models in different conversion (α) ranges for the wastes and their blends. Finally, the presence of alkaline and alkaline-earth elements (Na, K, Mg, and Ca) was confirmed through ash characterization. Thus, the ash can be considered a possible supplementary cementing material for end-use applications. [ABSTRACT FROM AUTHOR]

Co-combustion of coal and biomass can reduce carbon emissions from fossil fuel use and enable cleaner energy use. The combustion process of bituminous coal (BC) with three typical biomasses: agricultural waste (Wheat Straw, WS), forest waste (Pine, P), and marine biomass waste (Enteromorpha, EN) was investigated using the TGA and the controlled diffusion mechanism model. When the combustion thermodynamic behavior of the blends was analyzed, it was found that when the proportion of biomass blending increases, the ignition point temperature of its blend with coal decreases and improves the combustion performance of the fuel. WS and P promote combustion of BC/WS and BC/P blends, respectively. EN incorporation gives BC/EN blend a slagging tendency and reduces the burnout of the blend. The kinetic parameters of the three fuel blends were calculated using Coats–Redfern method. The kinetic mechanism analysis shows that the combustion mechanisms of the three biomass-coal blends are in accordance with the diffusion mechanism model, and the activation energy of the blends decreases with the increase in the biomass blending ratio after the temperature increases to 350 °C. After adding biomass its co-combustion with coal has obvious synergistic interactions, in which coal and enteromorpha synergistic effect is the best. The change of activation energy of mixed combustion of coal and biomass is affected by the content of volatiles in biomass. Coal-biomass mixtures can improve bituminous coal combustion. Alkali metals in biomass have an inhibitory effect on co-combustion of the coal-biomass mixture. [ABSTRACT FROM AUTHOR]

The combustion of coal creates many environmental and health problems, apart from it has many problems associated with the power plant combustor during the use of coal with the impurities. Biomass utilization could be the best option for the use as co-feed with coal. Coal biomass co-combustion was observed in this work, and different blends of coal and biomass were prepared. Banana tree waste, cow dung, and tree leaves were selected as biomass fuel for this study. It was observed that the coal biomass blend has less emission gases as compared to raw coal, and the amount of CO, CO2, and SO2 was reduced that was in higher amount in raw coal. At a ratio of 60% of Lakhra coal and 40% of cow dung manure, the lowest of CO emission was observed, that was 580 ppm, and at the ratio of 60% of Lakhra coal, 40% of tree leaves. The SO2 emission was reduced from 377 to 170 ppm. Minimum carbon monoxide was observed for the blend of 70% Lakhra coal and 30% cow dung manure. The calorific value of biomass was increased with coal bland the bland of 70% Lakhra coal and 30% cow dung has the highest calorific value. Also, the thermogravimetric properties were increased in the coal biomass blend. The mass reduction was slow at the start while it was suddenly increased in zoon one from temperature 0 to 200 °C. while zoon two from 200 to 800 °C mass reduction was increased with higher rate and zoon three mass reduction was stopped. [ABSTRACT FROM AUTHOR]

Ammonia, being a carbon-free fuel, is garnering increasing attention in the combustion community. However, its application is still impeded by its limited stability range and significantly NOx emissions. This study delves into the impact of primary and overall equivalence ratios (ϕ pri and ϕ ovr) on emissions production in ammonia–hydrogen co-firing flames, utilizing a two-stage swirling model gas turbine combustor. The emissions concentration is measured using Fourier Transform Infrared Spectroscopy (FTIR). The physical and chemical processes influencing emissions production are comprehensively analyzed through a combination of Large Eddy Simulation (LES) and Flamelet-Generated Manifold (FGM) method. The reliability of the simulation is validated by the experimental data, showing a good capability in predicting the combustion. Results indicate that the two-stage combustion strategy exhibits significantly controlling effects on NOx and unburned NH 3 emission. The NO emission exhibits a non-monotonic variation with ϕ pri , reaching its lowest value at ϕ pri ≈ 1.2. Further analysis shows that ϕ pri plays a crucial role in determining the temperature and OH concentration in the primary combustion zone, thereby influencing NOx production in this area. When the primary zone is operated at lean condition, the reduction on NO in secondary zone is primarily attributed to dilution effect by the secondary air. In contrast, when ϕ pri > 1, the concentrations of the main emissions in secondary zone are dominated by chemical effects. In this scenario, unburned NH 3 and H 2 from the primary zone are consumed, resulting in a substantial production of NO in the secondary combustion zone. Additionally, with an increase in ϕ pri , the secondary NO production also increases. The ϕ ovr exhibits two considerable effects. On one hand, an increase in ϕ ovr results in a higher local equivalence ratio in the secondary zone, thereby promoting local NOx production. Simultaneously, the elevated flame temperature enhances the consumption of N 2 O. On the other hand, the rise in ϕ ovr results in a reduction in vortex scale and residence time in the secondary combustion zone, leading to a decrease in local NO production. • The NOx mitigation of NH 3 /H 2 /air co-firing flames have been achieved through the secondary staged air. • The proposed LES-FGM method was validated adequate predicting the flow field and emission characters. • The impact of primary and overall equivalence ratio on emissions have been revealed in-depth. • The optimal operating condition for emission control in the current combustor has been proposed. [ABSTRACT FROM AUTHOR]

Shaerhu (SEH) coal is abundant in Xinjiang, China. The utilization of SEH suffers from severe ash deposition, slagging, and fouling problems due to its high-chlorine-alkaline characteristics. The co-combustion of high-alkaline coal and other type coals containing high Si/Al oxides has been proven to be a simple and effective method that will alleviate ash-related problems, but the risk of heavy metals (HMs) contamination in this process is nonnegligible. Hence, the volatilization rates and chemical speciation of Pb, Cu, and Zn in co-combusting SEH and a high Si/Al oxides coal, i.e., Yuanbaoshan (YBS) coal were investigated in this study. The results showed that the addition of SEH increased the volatilization rates of Pb, Cu, and Zn during the co-combustion at 800°C from 23.70%, 23.97%, and 34.98% to 82.31%, 30.01%, and 44.03%, respectively, and promoted the extractable state of Cu and Zn. In addition, the interaction between SEH and YBS inhibited the formation of the Pb residue state. SEM-EDS mapping results showed that compared to Zn and Cu, the signal intensity of Pb was extremely weak in regions where some of the Si and Al signal distributions overlap. The DFT results indicated that the O atoms of the metakaolin (Al 2 O 3 ⋅2SiO 2) (001) surface were better bound to the Zn and Cu than Pb atoms after adsorption of the chlorinated HMs. These results contribute to a better understanding of the effects of high-alkaline coal blending combustion on Pb, Cu, and Zn migration and transformation. [Display omitted] [ABSTRACT FROM AUTHOR]

Herein, an affordable strategy was developed to form Pd@SiO2 nanostructure assembled onto monolithic AlOOH/Al nanoarrays from nano- to macro-scale by a one-step reaction process. (3-Aminopropyl)trimethoxysilane (APTMS) was employed as a dual-role reagent for the bidirectional bridging between Pd2+ and AlOOH/Al, as well as the formation of SiO2 matrix and mesopores. The effects of one-step organization conditions on the preparation process, catalyst structure, and catalytic performance were all studied. High hydroxyl contents in Al-based nanoarrays promoted the silanization reaction of APTMS deposition, resulting in a well-formed SiO2 shell and abundant mesopores during the thermal decomposition of APTMS. APTMS amount was not only related to SiO2 loading and encapsulation effect of the core–shell structure, but also affected Pd accessibility. Such proposed APTMS-assisted protocol for the in-situ organization of monolithic Pd@SiO2 catalysts can effectively prevent the growth and aggregation of Pd NPs, thereby favoring low-temperature activity and stability for CH4 combustion. Monolithic Pd@SiO2 catalysts supported on AlOOH/Al nanoarrays were successfully fabricated from nano- to macro-scale in one step for improved thermal stability of CH4 combustion. The cost-effective coupling agent (APTMS) acted as the bidirectional bridging between –NH2 of APTMS and Pd2+ through preferential chelation, as well as a silanization reaction between methoxy groups of APTMS and surface –OH groups on AlOOH nanoarrays to form Al–O–Si bonds. [ABSTRACT FROM AUTHOR]

The paper explores the potential of the main state economic incentive (Conto Termico) designed to promote the use of renewable energy sources for heating and cooling purposes in residential buildings, aiming to reduce primary air emissions from residential biomass combustion (RBC). For this purpose, an emission reduction scenario involving the technological transition of biomass residential heating appliances was implemented in the lowland small‐medium municipalities of the Lombardy region in Italy, where households are connected to the natural gas grid but RBC is often practiced for economic reasons, contributing to severe air pollution problems related especially to particulate matter (PM) emissions. This technological turnover scenario (i.e. all biomass appliances in the area replaced by state‐of‐the‐art pellet appliances) resulted in a significant reduction of particulate matter emissions, while having only a minimal impact on NOx emissions. The incentivized cost for technological turnover (€15/kgPM10 avoided) was in line with the social costs associated with health impacts related to PM10 in a rural setting such as the study area. Given the one‐off investment support provided by a recently adopted national decree (DM 15/09/2022), biomethane emerges as a promising renewable energy alternative to decrease PM and NOx emissions from RBC in Lombardy region, characterized by an extensive natural gas distribution network and potential waste feedstock for biomethane production. Despite the still elevated production costs, an analysis restricted to the incentivized segment reveals that supporting biomethane production through investment incentives is more cost‐effective (€8/kgPM10 avoided) than promoting technological turnover. [ABSTRACT FROM AUTHOR]

For a 300 MWe anthracite- and arch-fired boiler with biased-swirling-secondary-air (BSSA) technology, the distribution law of gas/solid two-phase velocity in the furnace is obtained with the help of a 1:10 cold modeling experiment bench, and the combustion and NOx formation characteristics in the furnace are revealed by numerical calculation. The results show that, with the increase of over-fire air rate, the reflux velocity in the reflux zone under the arch decreases continuously, and when the main air flow from the furnace arch reaches the staged air region from the vent air region, the position of particle flow in the primary air turn upward is advanced, and the utilization rate of the space in the lower furnace will decrease continuously. In the regions of vent air and staged air, when the over-fire air rate increases from 15% to 25%, the maximum vertical velocity decreases by approximately 2 times, and the downward depth of air flow from the furnace arch decreases significantly. When the over-fire air rate is increased from 10% to 25%, the thermal resistance between the primary air of the burner and the high-temperature flue gas in the furnace center increases, the ignition of the primary pulverized coal air flow is advanced, the flue gas temperature in the center of the lower furnace is decreased. As a result, with the increase of over-fire air rate, the combustible content of fly ash increases continuously. Especially, when the over-fire air rate increases from 20% to 25%, the combustible content of fly ash increases significantly. With the increase of the over-fire air rate, the high CO concentration region in the primary combustion zone expands, the reducing atmosphere is strengthened, the formation of NOx is effectively restrained, and the NOx emission concentration at the furnace outlet continues to decreases. In particular, when the over-fire air rate increases from 15% to 20%, the NOx emission concentration decreases greatly. After the swirling secondary air of the arch-fired boiler is biased, the setting of over-fire air rate is recommended to be 20%, and the NOx emission concentration and combustible content of fly ash are 694 mg/m3(O2 = 6%) and 7.32%, respectively. Compared with a traditional swirling arch-fired boiler, the combustible content of fly ash and NOx emission concentration are reduced by 46.8% and 34.1%, respectively. [ABSTRACT FROM AUTHOR]

The co-combustion characteristics of furfural residue (FR) and oil shale (OS) were investigated in a thermogravimetric analyzer under different heating rate (10, 30, 50 °C/min) and mixing ratio (1:0; 3:1; 1:1; 1:3; 0:1). The effects of synergy was estimated by using the interaction coefficient, and the kinetics were looked at using the Coats-Redfern method in the co-combustion of furfural residue (FR) and oil shale (OS). To obtain the maximum the flammability index (C) and comprehensive combustion characteristic index (CCI), and minimum activation energy (Em), the response surface method (RSM) was employed to find the best mixing ratio and heating rate. The ignition temperature (T1) and burnout temperature (T2) went down as the FR mixing ratio went up, but the fuel's highest burning rate (Rmax), the average burn rate (Ra), C, and CCI of mixed samples went up as the FR mixing ratio went up. The sample's T1, T2, Rmax, Ra, C, and CCI all went up as the heating rate went up. As the rate of heating went up, E of combustion went down. E of mixed fuel combustion was lower than E of FR combustion alone, which showed that there were interactions in the mixed combustion. The effects of this synergy were clearer when the temperature was higher. According to the model optimization, the optimal conditions were obtained. [ABSTRACT FROM AUTHOR]

This study investigates the co‐combustion of palm oil biodiesel fuel, as a renewable alternative for diesel fuel, inside natural gas flame to enhance the flame thermal specifications and NOx reduction. A power natural gas burner with a maximum heat capacity of 418,400 kJ/h was installed at the inlet of a laboratory furnace and biodiesel fuel was injected inside natural gas burner with a 100 μm in diameter solid cone nozzle. Flame temperature, thermal radiation, Infrared radiation, and CO, CO2 and NOx emission were measured. The results revealed that biodiesel injection increases the flame size and turns the non‐luminous blue flame into yellow‐colored flame. Furthermore, higher flash point and Sauter Mean Diameter of biodiesel promote the thermal decomposition of fuel droplets and increase the concentrations of Intermediate Soot Particles in the flame which in turn increases the flame emissivity coefficient and consequently flame thermal radiation. Also, the oxygen content of biodiesel fuel has an important role in the complete combustion of Intermediate Soot Particles to CO2 which increases the heat release of biodiesel combustion and raises the flame temperature. The average enhancement in thermal radiation and flame temperature were 5.6% and 43.38%, respectively. Finally, although biodiesel injection increases the flame temperature, it also increases the flame surface reaction and eliminates the hot spot region in the flame. Therefore, the rate of heat generation per unit volume of flame decreases and this decreases the rate of NOx emission as much as 10.84%. [ABSTRACT FROM AUTHOR]

Compared to conventional monoethanolamine (MEA), alternative solvents are expected to substantially contribute to reduce the energy demand of postcombustion CO2 capture from flue gases. This study presents a comprehensive techno-economic analysis of a 27wt% 2-amino-2-methyl-1- propanol (AMP) + 13wt% piperazine (PZ) aqueous solution for CO2 capture, compared to a 30 wt% MEA solution. The study addresses the retrofit of a carbon capture unit to a biomass-fired combined heat and power (CHP) plant, effectively making it a bioenergy with a carbon capture and storage (BECCS) system. The treated flue gas has a flow rate of 23 tons/hour (t/h) with 11.54 vol% CO2 and a 90% capture rate is aimed for. Aspen Plus V14 was employed for process simulations. Initially, binary interaction parameters for AMP/PZ, AMP/H2O, and PZ/H2O are regressed using vapor-liquid equilibrium (VLE) data, which were retrieved from literature along with reaction kinetics. Validation of parameters from available experimental literature yields an average absolute relative deviation (AARD) of only 5.9%. Afterwards, a process simulation model is developed and validated against experimental data from a reference pilot plant, using a similar AMP/PZ blend, resulting in 5% AARD. Next, a sensitivity analysis optimizes operating conditions, including solvent rate, absorber/stripper packing heights, and stripper pressure, based on regeneration energy impact. Optimized results, compared to MEA, reveal that AMP/PZ reduces the energy consumption from 3.61 to 2.86 GJ/tCO2. The retrofitting of the capture unit onto the selected CHP plant is examined through the development of a dedicated model. Two control strategies are compared to address energy unavailability for supplying the capture unit. The analysis spans 4 months, selected to account for seasonal variations. At nominal capacity, CO2 emissions, rendered negative by biomass combustion and CO2 capture, reach a maximum of -3.4 tCO2/h compared to 0.36 tCO2/h before retrofitting. Depending on the control strategy and CHP plant operating point, the Specific Primary Energy Consumption for CO2 Avoided (SPECCA) ranges from 4.91 MJ/kgCO2 to 1.76 MJ/kgCO2. Finally, an economic comparison based on systematic methodology reveals a 7.87% reduction in capture cost favoring the AMP/PZ blend. Together, these findings highlight AMP/PZ as a highly favorable alternative solvent. [ABSTRACT FROM AUTHOR]

At present, there is a global rise in electricity consumption, leading to an accelerated depletion of natural resources due to the reliance on fossil fuels to fulfill this energy demand. Consequently, there exists a worldwide emphasis on enhancing the proportion of renewable energy sources in electricity generation. Biomass, as a renewable energy source, presents a viable alternative to certain fossil energy sources for combustion in electricity generation. This study focuses on a 660 MW coal-fired power plant as the subject of investigation, employing Aspen Plus simulation software (V11) to replicate the operational dynamics of the plant. A model of the direct mixed combustion biomass system within the coal-fired boiler is constructed, and its accuracy is validated against operational data obtained from the power plant. Moreover, a model elucidating the direct co-combustion of biomass in a coal-fired boiler, augmented by flue gas recirculation, was developed through the integration of biomass pre-treatment and flue gas recirculation technologies. This study explores the impacts of varying biomass blending ratios and flue gas recirculation on parameters, including flue gas volume, power generation efficiency, boiler performance, water vapor content, and emissions of pollutants. These findings indicate an inverse relationship between the mixing ratio and various performance metrics as follows: power generation, boiler efficiency, as well as NOX and SO2 content, with larger mixing ratios resulting in diminished values. Furthermore, the incorporation of flue gas recirculation was observed to mitigate furnace temperatures and suppress NOX emissions. [ABSTRACT FROM AUTHOR]

This paper investigates the combustion characteristics and pollutant emission patterns of the mixed combustion of lignite (L) and torrefied pine wood (TPW) under different blending ratios. Isothermal combustion experiments were conducted in a fixed bed reaction system at 800 °C, and pollutant emission concentrations were measured using a flue gas analyzer. Using scanning electron microscopy (SEM) and BET (nitrogen adsorption) experiments, it was found that torrefied pine wood (TPW) has a larger specific surface area and a more developed pore structure, which can facilitate more complete combustion of the sample. The results of the non-isothermal thermogravimetric analysis show that with the TPW blending ratio increase, the entire combustion process advances, and the ignition temperature, maximum peak temperature, and burnout temperature all show a decreasing trend. The kinetic equations of the combustion reaction process of mixed gas were calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) kinetic equations. The results show that the blending of TPW reduces the activation energy of the combustion reaction of the mixed fuel. When the TPW blending ratio is 80%, the activation energy values of the mixed fuel are the lowest at 111.32 kJ/mol and 104.87 kJ/mol. The abundant alkali metal ions and porous structure in TPW reduce the conversion rates of N and S elements in the fuel to NO and SO2, thus reducing the pollutant emissions from the mixed fuel. [ABSTRACT FROM AUTHOR]

A widespread recovery of waste heat requires a cost‐effective production of thermoelectric generators. Thermoelectric oxides are predestined for use at high temperatures. For manufacturing reasons, a multilayer generator design will be easily scalable and cost‐effective. To evaluate the potential of ceramic multilayer technology for that purpose, a multilayer of the promising thermoelectric oxides calcium cobaltite (Ca3Co4O9), calcium manganate (CMO, CaMnO3), and glass–ceramic insulation layers is fabricated. Cracks and reaction layers at the interfaces are observed in the microstructure. The compositions of these reaction layers are identified by energy‐dispersive X‐ray spectroscopy and X‐ray diffraction. Mechanical and thermal properties of all layers are compiled from literature or determined by purposeful sample preparation and testing. Based on this data set, the internal stresses in the multilayer after co‐firing are calculated numerically. It is shown that tensile stresses in the range of 50 MPa occur in the CMO layers. The reaction layers have only a minor influence on the level of these residual stresses. Herein, it is proven that the material system is basically suitable for multilayer generator production, but that the co‐firing process and the layer structure must be adapted to improve densification and reduce the tensile stresses in the CMO. [ABSTRACT FROM AUTHOR]

When designing settlements according to the "Green Building" principle, it is necessary to develop a heating system based on climatic conditions. For example, in areas with a sharply continental climate (cold and prolonged winters), it is sometimes necessary to use solid fuel boilers (in the absence of gas). However, to use these, it is necessary to use biomass or biomass-coal blends as fuel to increase their combustion heat. The addition of biomass waste to coal can be aimed at achieving various objectives: utilization of biomass waste; reduction of solid fossil fuel consumption; improvement of environmental performance at coal-fired boiler houses; improvement of the reactivity of coals or to improve the technical and economic performance of heat-generating plants due to the fact that biomass is a waste from various types of production, and its cost depends only on the distance of its transportation to the boiler house. In this work, combustion of various biomass wastes, including sewage sludge, was carried out on a fire bench emulating the operation of a boiler furnace. Fuel particles were ignited by convective heat transfer in a stream of hot air at a velocity of 5 m/s in the temperature range of 500–800 °C, and the experimental process was recorded on a high-speed, color video camera. The obtained values were compared with the characteristics of different coals used in thermal power generation (lignite and bituminous coal). The aim of the work is to determine the reactivity of various types of biomass, including fuel mixtures based on coal and food waste. The work presents the results of technical and elemental analysis of the researched fuels. Scanning electron microscopy was used to analyze the fuel particle surfaces for the presence of pores, cracks and channels. It was found that the lowest ignition delay is characteristic of cedar needles and hydrolyzed lignin; it is four times less than that of lignite coal and nine times less than that of bituminous coal. The addition of hydrolysis lignin to coal improves its combustion characteristics, while the addition of brewer's spent grain, on the contrary, reduces it, increasing the ignition time delay due to the high moisture content of the fuel particles. [ABSTRACT FROM AUTHOR]

The multiferroic magnetoelectric 2–2 laminated composite systems with BaTiO3 and NiFe2O4 as the ferroelectric and ferrimagnetic phases were successfully fabricated by co-firing technique. For this phase, pure BaTiO3 and NiFe2O4 were successfully synthesized by sol–gel and polyol method, respectively. The structural, microstructural, multiferroic and magnetoelectric coupling properties of phase pure and co-fired systems were investigated using X-ray diffraction, HR-TEM, SEM–EDX, P–E Loop, VSM and magnetoelectric coupling analysis. The multiferroic and magnetoelectric coupling properties of the laminated systems were compared with the mixed system having similar weight percentage of BaTiO3 and NiFe2O4. The fabricated composite systems show good multiferroic and magnetoelectric properties. Compared to mixed composite systems, the laminated structure has an enhanced magnetoelectric (ME) coupling of 6.42 mV/cm.Oe. This variation in ME coupling is attributed to the low leakage current effects in the laminated systems. The ME coupling in the laminates varies with the nature and number of layers. For laminated composite systems, the ME coupling coefficient is found to increase from 6.42 mV/cm.Oe to 10.48 mV/cm.Oe with increase in the number of layers. [ABSTRACT FROM AUTHOR]

The accumulation of excess manure and the energy costs of the buildings housing the animals are the most important problems that chicken farms have to face nowadays. The combustion of chicken manure to obtain thermal energy for animal holdings has been demonstrated through the research project AVIENERGY, in Spain. To ensure the circularity of the process, the combustion by-product, bottom ash, needs to be recycled and used. This work studies the agricultural use of ash from chicken manure combustion as a fertiliser product and determines its capacity for mineral fertiliser substitution. Ashes from cocombustion of chicken (broiler) manure with wood at different proportions were chemically analysed to determine their nutrient concentrations and availabilities. Then, one ash sample was used as a fertiliser for lettuce cultivation in a pot experiment. Different application rates were tested according to the phosphorus (P) content of the ash, being equivalent to 50, 65, 80 and 100% of the standard inorganic P fertilisation. The results indicate that the ash from combustion of chicken manure meets the requirements for inclusion in the fertiliser component material category 'CMC 13', and can be used for the preparation of fertiliser 'PFC 1(C)(I)(a)(ii): Compound Solid Inorganic Macronutrient Fertiliser (multi-nutrients)', and also possesses characteristics of "PFC 2: Liming Material" according to the EU legislation for fertiliser products. Although plant production was slightly reduced with ash fertilisation, the ashes reached a fertiliser capacity able to substitute 80% of the mineral P fertiliser, with a liming capacity of 30%. Hence, the ash from chicken manure combustion could be applied to soil, especially if acidic, in partial substitution of mineral fertilisers, to supply P. [ABSTRACT FROM AUTHOR]

The coupled combustion of coal with the carbon-free fuel NH 3 is an effective technology for reducing CO 2 emissions. Based on elemental analysis, proximate analysis, Fourier Transform infrared spectroscopy (FTIR), Carbon-13 Nuclear Magnetic Resonance (13C NMR), and X-ray photoelectron spectroscopy (XPS) characterizations, a coal macromolecular model was constructed. The combustion characteristics of coal/NH 3 co-firing were investigated by reactive force field molecular dynamics simulations (ReaxFF MD). The transformation mechanism of elemental N was elucidated. The influence of temperature, oxygen concentration, and NH 3 co-firing ratio (CR) on products was investigated. The results showed that during the non-isothermal combustion phase, the coal macromolecules decomposed more rapidly when the heating rate was low. In the isothermal phase, high temperatures promoted secondary reactions. The production of inorganic gases increased with increasing temperature. As the molar fraction of NH 3 increased, the production of CO 2 and CO was effectively reduced. There were three main pathways for NO formation. As NH 3 decomposed to form NH 2 , NH 2 was subsequently converted to NH, and NH reacted with O 2 to form NO. The NH 2 could also react with O radicals to form HNO, which was then converted to NO. Besides, both thermal NO x and prompt NO x were generated since the N 2 was involved in the reaction. In addition, the production of NO x increased significantly at oxygen concentrations greater than 1.4. [Display omitted] • The molecular model of coal was constructed based on experimental characterization. • Coal/NH 3 co-combustion characteristics were studied using ReaxFF MD. • The lower heating rates during heating contributed to decomposition of molecules. • High temperature promoted the secondary decomposition of tar in combustion systems. • The mechanisms for the conversion of nitrogen-containing products were revealed. [ABSTRACT FROM AUTHOR]

Solvent-based CO2 capture is a commonly employed post-combustion technique in processes involving absorber-stripper columns. This study focused on computer simulations with equilibrium- and rate-based modeling of CO2 capture using the amine solvents 2-amino-2-methyl-1-propanol (AMP), diethanolamine (DEA), and methyl diethanolamine (MDEA) and thermodynamic methods involving electrolyte NRTL models. The objective of this study was to understand the impacts of rate-based modeling, the type of amine, and thermodynamic methods on carbon capture. Within this study, the amine-based CO2 capture process from coal-power plant flue gas was studied using Aspen Plus modeling. Simulations were also conducted to determine the impact of thermodynamics and kinetics on the CO2 capture performance of the system. The results were analyzed on the basis of captured CO2 according to the solvents and models. The equilibrium approach was mostly invalid because of the oversimplified ideal stage assumptions through the column. The lowest carbon capture capacity was obtained with MDEA, while DEA yielded the best results. A sensitivity analysis with rate-based modeling showed the significant impact of the inlet CO2 composition. The amine-based CO2 capture process simulation included solution chemistry, electrolyte thermodynamics, rigorous transport property modeling, reaction kinetics, and rate-based multistage simulation, which could be applicable to different solvent systems. [ABSTRACT FROM AUTHOR]

The results of experimental studies of the cocombustion of coal–water fuel with fuel oil are presented. According to the results of experimental studies, the efficiency of joint ignition of stationary single droplets of coal–water fuel and fuel oil was substantiated. A decrease in the ignition delay times of fuel droplets was found in comparison with the ignition of only coal–water fuel droplets under identical conditions. A significant decrease in the ignition delay times of coal–water fuel droplets is typical for droplets with sizes of 2 and 3 mm in the entire studied temperature range of the oxidizer (from 873 to 1,273 K) and distances (from 2 to 4 mm) between drops of coal–water fuel and fuel oil. It has been experimentally established that the reduction of ignition delay times is 58 and 70%. For droplets of coal–water fuel with a characteristic size of 1 mm, the changes in ignition delay times are ambiguous. The joint combustion of coal–water fuel and fuel oil affects the ignition of droplets of coal–water fuel, and the characteristic size of which is more than 1 mm. With this method of burning coal–water fuel and fuel oil, the latter acts as a catalyst when igniting coal–water fuel, thereby ensuring a stable combustion of such fuel. The combustion of two-component coal–water fuel together with fuel oil can avoid the problems typical of such fuels: reduce the requirements for spraying devices, solve the problem of low reactivity, increase the completeness of combustion of this fuel, and fully use it in the production of thermal and electrical energy. [ABSTRACT FROM AUTHOR]

Experimental measurements and modeling have been performed in the chimney of a biomass boiler to study the gaseous and particulate matter (PM) emissions during the combustion of wood pellets. A 10 kW boiler with an underfeed burner is equipped with different sensors located in the chimney (anemometer, thermocouples). The PM emissions were measured in the chimney through the engine exhaust particle sizer (EEPS) technique. Moreover, the gaseous emissions (CO2, CO, total hydrocarbons THC, O2) were obtained through infrared (IR) spectroscopy and flame ionization detector (FID). The emissions were recorded during the steady phase of the boiler and averaged over several tests. Four locations were investigated in the chimney to evaluate the evolution of the particle size and the potential deposition on the surface. The experimental results were compared with a CFD model with particle transportation. The modeling of turbulent flow in the chimney is based on a Reynolds-averaged Navier–Stokes (RANS) approach with turbulent viscosity closure. To account for flow anisotropy, the v 2 ¯ − f turbulence model was selected for this study. The effect of turbulent fluctuations on the discrete phase is considered by the discrete random walk (DRW) turbulent dispersion model. The results obtained provide access to the topology of the carrier phase flow as well as the complete distribution of the particle field within the chimney enclosure. Advanced measurement of pollutant emissions and modeling of the PM transportation are developed for the first time in a domestic biomass boiler operating in real conditions. Experimental results demonstrate several relevant information. The CO and THC emissions show a similar evolution versus time. The PM granulometric distribution measured along the chimney highlights the particle agglomeration phenomena. Moreover, the CFD model and experimental results give similar results in terms of flow characteristics and PM granulometry. [ABSTRACT FROM AUTHOR]

The treatment of sewage sludge has become a global concern. Large amounts of sewage sludge can be disposed of by burning coal-mixed sludge. Thermogravimetric analysis and lab-scale combustion experiments in a drop tube furnace were utilized to study the combustion characteristics, pollutant emissions, and heavy metal migration during the co-combustion of coal and sewage sludge. The results showed that the blended fuels with a sewage sludge content less than 10 weight percent exhibited coal-like combustion characteristics. Additionally, the additional sewage sludge favored the ignition performance of blended fuels. When sewage sludge was added, the SO2 emissions rose to 76 mg/Nm3 under the 10% sludge condition—nearly three times higher than that of coal alone. While NOx emissions stayed mostly unchanged, HCl and HF emissions were very low. Meanwhile, Cr, Cu, and Ni migrated to the bottom ash, and their concentrations were all reduced with an increase in sewage sludge. Pb, Cd, Cr, Cu, Ni, and Hg migrated to the flue gas, mostly in the form of gaseous components. The results provide crucial information in the co-combustion of sewage sludge and coal, with implications in the development and improvement of large-scale, harmless, and resource-recovering techniques for waste sludge. [ABSTRACT FROM AUTHOR]