Search

Flame stabilization distribution and efficient fuel mixing are highly significant in the performance of ramjet engine. In this paper, numerical studies are done to investigate the supersonic combustion of hydrogen and air co-flow in presence of the ramp edge. In this study, flame maintenance and combustion formation in a dual-combustion ramjet engine are fully investigated. The primary emphasis of this work is to disclose the impact of produced shocks due to the existence of ramp edge on the structure of fuel and air-jet immediately downstream of injector. The shock interactions of two different angles (10 deg and 30 deg) of the ramp edge are investigated. Favre-averaged conservation equations are considered for the simulation of compressible flows inside the combustor. Various mechanisms expressing the flame spreading characteristics are also examined. Depending on the angle of the ramp edge, the produced shock waves influence on size and strength of vortices. Our findings also show that high angles of ramp edge augment the fluctuation of the vortices by the splitter and consequently, fuel mixing enhances in the combustion chamber of ramjet engine. Our findings also confirm that the similar jet pressure would be more effective on the vortex production downstream of the splitter. The application of ramp edge with angle of 30 deg would increase average momentum thickness of the mixing layer up to 55%. [ABSTRACT FROM AUTHOR]

In this study, the combustion characteristics of pine needles, pine needle humus, and the co-combustion of these two types of biomass with coal were compared. In addition, the optimization of the combustion performance of coal/humus was assisted through the following studies: (i) the combustion performance of coal/pine needle humus was studied under four different oxygen concentrations (N2, 10%O2/90%N2, 20%O2/80%N2, and 40%O2/60%N2); (ii) the synergistic effect between the humus and coal during combustion was also investigated by adjusting the blending ratio and oxygen content; (iii) the mechanisms of the optimized combustion processes were expounded by kinetics and thermodynamics discussion. The results demonstrated that the combustion characteristics of the coal/humus blends were found to be higher than those of the coal/pine needle blends. The coupling interactions of the oxygen content and blending ratio contributed to the significant synergistic effect between the two fuels, and the synergistic effect showed a nonlinear variation with an increased oxygen concentration. The synergistic effect in a rich oxygen environment (O240%/N260%) is 5.1 times greater than that in the synthetic air (O220%/N280%) and 13.8 times greater than that in the oxygen-poor environment (O210%/N290%). Hence, the blending ratio could be adjusted to maintain the intensity of the synergistic effect in an oxygen-rich atmosphere. [ABSTRACT FROM AUTHOR]

Combustion behavior of rice straw torrefied at 300 °C for different residence time and their blends with sub-bituminous coal was investigated. The torrefied product and its blends were characterized for fuel properties and Hardgrove Grindability Index (HGI). Also, the torrefied product is characterized fordensity, proximate and ultimate analysis, energy yield, and structural analysis by Raman spectroscopy. The calorific value data of blend shows its value is equivalent to the value of sub-bituminous coal, i.e., 17.21 MJ/kg. On the other hand, HGI of torrefied product is 40–45 and that of coal is 80. On blending, the value of HGI up to a certain ratio shows the synergetic effect while higher content of the torrefied product in blend demonstrated non-additivity behavior and it is dominated by coal as a consequence of density difference between torrefied product and coal. Characteristic combustion parameter for blends reveals the synergetic behavior. It is found that the blend of torrefied products and sub-bituminous coal at a ratio of 10:90 and 20:80 had ignition and burnout temperature almost close to coal sample. The ignition and burnout temperature of 10:90 of torrefied product at 300 °C for 60 and 120 min are 295 °C and 507 °C, 301 °C and 505 °C whereas that of sub-bituminous coal is 325 and 515 °C. The change in the fuel properties of the blend suggests there is a certain degree of interaction that occurred during combustion. [ABSTRACT FROM AUTHOR]

Copyright of Piezoelectrics & Acoustooptics is the property of Piezoelectric & Acoustooptic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of SDU Journal of Engineering Sciences & Design / Mühendislik Bilimleri ve Tasarım Dergisi is the property of Journal of Engineering Sciences & Design and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Co-firing NH 3 in coal-fired power plants is an attractive method to accelerate the pace of global decarbonization. However, the contradiction between achieving elevated temperature within the furnace and maintaining low NO x emission constrains the utilization of NH 3 as fuel. In this study, 3-dimensional numerical simulations on coal/NH 3 co-firing cases were conducted in a full-scale boiler for the first time. The influences of NH 3 blending ratio, O 2 enrichment combustion and deep air-staging technology were investigated. The results show that the burnout properties of NH 3 are excellent in co-firing boiler. Higher NH 3 blending ratio leads to lower temperature in the furnace. Enriching O 2 concentration to 30% in the secondary air can compensate the temperature decline caused by 50% NH 3 co-firing, while it brings an undesired surge in NO x concentrations. The high temperature and strong reducing atmosphere (HT&SRA) could be created by combining the O 2 enrichment and deep air-staging combustion. The NO emission drops by 49.6% due to HT&SRA. Then, high flue gas temperature and low NO x emission can be achieved simultaneously. HT&SRA improves the overall exergy efficiency for 50% NH 3 co-firing case from 51.65% to 51.78%. The findings open up a promising strategy for utilizing NH 3 as a stationary fuel. • NH 3 shows excellent burnout characteristics in the full-scale utility boiler. • The flue gas temperature drops by more than 100 K when NH 3 blending ratio is 50%. • 30% O 2 compensates the temperature decline, but increases NO emissions by 47.2%. • NO emission drops by 49.6% under high temperature & strong reducing atmosphere. • HT&SRA improves the exergy efficiency from 51.65% to 51.78% for 50% NH 3 case. [ABSTRACT FROM AUTHOR]

The pyrolysis processing of waste tires is a promising technology for obtaining products with high marginality. One of the possible methods of solid pyrolysis product utilization is its combustion for energy production, but this is complicated by poor reactivity and sulfur emissions. The combustion of char together with more reactive fuels could solve this problem. The current study is devoted to the combustion characteristics of waste tires pyrolysis carbon residue mixed with biomass: pine sawdust and peat. The oxidation characteristics in thermal analyzer conditions were found to change insignificantly. In contrast, 15 wt% of peat and sawdust additives was found to decrease ignition delay times in realistic conditions of combustion at 800 °C by 42 and 78%, respectively, while the SO2 emissions also dropped by 73 and 52%, respectively. The extra sulfur was found to be contained in ash residue in the form of CaS and CaSO4. While increasing peat concentration from 5 to 15 wt% was found to have almost no effect, the same increase for sawdust resulted into an almost proportional decrease in ignition delay times. The results obtained could be used for the integration of waste tires pyrolysis char mixtures with peat or sawdust into the energy sector. [ABSTRACT FROM AUTHOR]

Co-combustion of cornstalk/coal blends is feasible for large-scale renewable energy commercialization. However, alkali and alkaline earth metals (AAEMs) in cornstalks can cause slagging/fouling problems. In this study, the ash micro-characteristics, slagging/fouling indexes, and combustion behavior of cornstalk, coal, cornstalk after pretreatment, and cornstalk/coal blends were investigated using scanning electron microscopy, X-ray diffraction, X-ray fluorescence, and thermogravimetric experiments. The results demonstrate that cornstalk ash is smoother than coal ash. There are few significant differences in the micromorphology and minerals between the coal and blends. Various chemicals were used to remove AAEMs, with the most to the least effective being (i) soaking in hydrochloric acid, (ii) soaking in ammonium acetate ≈ soaking in distilled water, and (iii) untreated. After soaking in hydrochloric acid, the mineral content containing potassium, calcium, and magnesium significantly decreased in cornstalk ash, except for sodium salt. All pretreatments can effectively lower the slagging/fouling indexes of cornstalk ash and blends. Pretreatment to remove AAEMs would restrain volatile release in cornstalk. The blend resists the volatile release of cornstalk but is helpful for the coke combustion of coal. AAEMs can lower some characteristic temperatures but do not increase the combustion rate and combustion characteristic parameters in the co-combustion of blends. [ABSTRACT FROM AUTHOR]

This review investigates the effects of the Brazilian agriculture production and forestry sector on carbon dioxide (CO2) emissions. Residual biomasses produced mainly in the agro-industrial and forestry sector as well as fast-growing plants were studied. Possibilities to minimize source-related emissions by sequestering part of carbon in soil and by producing biomass as a substitute for fossil fuel were extensively investigated. The lack of consistency among literature reports on residual biomass makes it difficult to compare CO2 emission reductions between studies and sectors. Data on chemical composition, heating value, proximate and ultimate analysis of the biomasses were collected. Then, the carbon sequestration potential of the biomasses as well as their usability in renewable energy practices were studied. Over 779.6 million tons of agricultural residues were generated in Brazil between 2021 and 2022. This implies a 12.1 million PJ energy potential, while 4.95 million tons of forestry residues was generated in 2019. An estimated carbon content of 276 Tg from these residues could lead to the production of approximately 1014.2 Tg of CO2. Brazilian biomasses, with a particular focus on agro-forest waste, can contribute to the development of sustainable alternative energy sources. Moreover, agro-waste can provide carbon credits for sustainable Brazilian agricultural development. [ABSTRACT FROM AUTHOR]

CO2 adsorption is one of the promising CCS technologies, and activated coke is a solid adsorbent with excellent adsorption properties. In this study, activated coke was prepared by using bituminous coal and coconut shells activated with KOH or CaCl2 in a physically activated atmosphere and modified with ammonia. The effect of the active agent impregnation ratio on the physicochemical properties of activated coke was investigated by N2 adsorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The CO2 adsorption performance of activated coke was tested, and the effect of nitrogen-containing functional groups on CO2 adsorption was investigated by experiments and simulations. The results showed that the specific surface area of activated coke reached 629.81 m2/g at a KOH impregnation ratio of 0.5 and 610.66 m2/g at a CaCl2 impregnation ratio of 1. The maximum CO2 adsorption capacity of activated coke reached 71.70 mg/g and 90.99 mg/g for conventional power plant flue gas and oxy–fuel combustion flue gas, respectively. After ammonia modification, the CO2 adsorption capacity of activated coke was further increased. Simulations showed that pyrrole and pyrrole functional groups changed the polarity of graphene and established weak interactions with CO2. [ABSTRACT FROM AUTHOR]

The co-combustion of various ultra-low volatile coal-based solid fuels (UVCFs) under oxy-fuel condition could consume semi-coke and residual carbon cleanly and efficiently. However, the fuel-nitrogen (fuel-N) migration behaviors of various UVCFs blends in O 2 /CO 2 atmosphere are still unclear. In addition, the heterogeneous reactions on surfaces of char could also affect the synergistic effects between various UVCFs blend. Here, the fuel-N migration features of various UVCFs in O 2 /CO 2 atmosphere were investigated by Chemkin simulation and the oxy-fuel co-combustion mechanism of various coal-based solid fuels (OCF mechanism) included heterogeneous reactions was developed. Moreover, the methods of sensitivity and rate of production analyses were both employed to clarify the synergistic effects on nitrogen conversion pathways of various blends. The heterogeneous reaction between char and NO (R15) is the key reaction for NO reduction in primary zone. The free radicals OH and H provided by UVCFs could react with main NO precursors NCO, HNCO, HOCN, NH and NH 2 to generate NO. The conversion pathways of HCN to NO are more complex than those of NH 3 to NO. The rises of residual carbons proportions and temperature in primary zone (T 1) could both reduce the NO formation amount due to the promoted R15. The sensitivity coefficients (S) on NO formation of 50% SS/50% CR blend in the burnout zone are lower than those of 50% SS/50% FR blend. The transformations of HNCO, HNO and NO 2 to NO and the heterogeneous reactions of NO could both be enhanced with the O 2 concentration in burnout zone. The increasing burnout air position (P b) results in the rise of NO generation owing to that the NO reducing reactions R15 and R16 are greatly inhibited with the P b raised. The present study could be beneficial for the clean and effective utilization of UVCFs, together with the reduce of NO x emission and realization of carbon neutral in China. [Display omitted] [ABSTRACT FROM AUTHOR]

There is a recognized need for developing the novel clean systems to solve the environmental and energy issues. In this regard, a novel tri-generation system of power, cooling and freshwater triggered by was developed. Emergy analysis was utilized for simultaneously evaluation of system from economic and environmental viewpoints. The effects of gasification temperature, combustion temperature and natural gas contribution in the input fuel to the supercritical carbon dioxide Brayton cycle were studied on system performance. Environmental loading ratio, Emergy sustainability index, Emergy investment ratio, Renewability scale, Emergy yield ratio and energy efficiency were considered as system performance indicators. Response surface methodology was utilized for four-objective optimization of the system performance. The results showed that natural gas contribution in the input fuel was the most effective parameter on system energy efficiency and increasing natural gas contribution in the input fuel resulted in improving the system energy efficiency. Maximization of Emergy sustainability index, minimization of Environmental loading ratio, minimization of Emergy investment ratio and maximization of energy efficiency were considered as the targets of the multi-objection optimization. The findings revealed that natural gas contribution in the input fuel of 1, gasification temperature of 1000 °C and combustion temperature of 1403 °C were the optimum conditions. Response surface methodology efficiently predicted the optimum outputs with errors smaller than 5%. [ABSTRACT FROM AUTHOR]

Light-emitting diodes are increasingly used as artificial light sources in Haematococcus pluvialis cultivation due to the fact of their energy advantages. The immobilized cultivation of H. pluvialis in pilot-scale angled twin-layer porous substrate photobioreactors (TL-PSBRs) was initially performed with a 14/10 h light/dark cycle and showed relatively low biomass growth and astaxanthin accumulation. In this study, the illumination time with red and blue LEDs at a light intensity of 120 µmol photons m−2 s−1 was increased to 16–24 h per day. With a light/dark cycle of 22/2 h, the biomass productivity of the algae was 7.5 g m−2 day−1, 2.4 times higher than in the 14/10 h cycle. The percentage of astaxanthin in the dry biomass was 2%, and the total amount of astaxanthin was 1.7 g m−2. Along with the increase in light duration, adding 10 or 20 mM NaHCO3 to the BG11-H culture medium over ten days of cultivation in angled TL-PSBRs did not increase the total amount of astaxanthin compared with only CO2 addition at a flow rate of 3.6 mg min−1 to the culture medium. Adding NaHCO3 with a 30–80 mM concentration inhibited algal growth and astaxanthin accumulation. However, adding 10–40 mM NaHCO3 caused algal cells to accumulate astaxanthin at a high percentage in dry weight after the first four days in TL-PSBRs. [ABSTRACT FROM AUTHOR]

Biomass energy is becoming the most promising renewable energy source as it can be used in various energy forms. One such use is the co-firing of pelletized biomass burnt with coal to minimize the impact of coal as an industrial energy source. In the present work, the effects of mixed torrefied pellet biomasses co-firing with coal were investigated. Corncob and khat stem were used as agriculture residues. The torrefied pellet of corncob and khat stem was co-fired with coal at temperatures of 766, 800, 850, 900, and 935 °C and residence times of 20, 60, 120, 180, and 220 s with pellet-to-coal ratios of 0.2, 0.25, 0.3, 0.4, and 0.45 g/g. The optimum parameters were investigated using central composite design (CCD) of response surface methodology. The combustion efficiency was profoundly enhanced in the range of 84.32–94.97% as the mixed torrefied pellet fraction increased from 20 to 30%. Statistical response surface optimizer exhibited that at a combustion temperature of 855 °C, a residence time of 177 s, and a torrefied pellet ratio of 0.33 g/g, the highest combustion efficiency of 93.22% was obtained. This study would be useful for proper design and operation of solid bio-fuel/coal co-firing combustion in the cement industries. [ABSTRACT FROM AUTHOR]

It is a continuous imperative to establish the most efficient process of conversion of primary energy from fuel through combustion, which also has the least possible harmful effect on the environment. In this time of expressed demands for decarbonisation, it also means the affirmation of the use of renewable fuels and the indispensable application of appropriate primary measures in the combustion furnace. At the same time, the efficiency of the combustion process depends on several factors, from the type and properties of the fuel to the ambient and technological settings for the process. In this regard, with the aim of determining the static characteristics of combustion, experimental laboratory research was carried out on the combustion of mixtures of brown coal with low heating value and a high ash content with waste woody biomass and different process conditions: temperature, staged combustion air supply (air staging) and in conditions of application of a third or additional fuel (natural gas, reburning technology). Applied experimental methods included the analysis of the combustion process on the basis of input (reactants) - output (products), including the analysis of the composition of flue gases, i.e. the determination of the emission of the key components of flue gases CO2, CO, NOx and SO2, as well as the analysis of the composition of slag, ash and deposits ash, i.e. assessment and evaluation of the behaviour of ash from fuel in that process. Based on the obtained research results, this paper shows the significant positive effects of the application of primary measures in the furnace - compared to conventional combustion: air staging - reduction of net CO2 emissions during co-firing with biomass and reduction of NOx emissions by up to 30%; reburning technology - additional reduction of CO2 and NOx emissions in proportion to the share of natural gas, e.g. at a combustion process temperature of 1350 °C and at a 10% energy share of natural gas during the co-firing of a mixture of brown coal and waste woody biomass, compared to the emission without the use of natural gas, a reduction of NOx emissions by 185 mg/mn 3 or by almost 30% was recorded. It was concluded, at the same time, the application of these primary measures in the furnace does not negatively affect the behaviour of ash from the fuel in the given settings of the combustion process. [ABSTRACT FROM AUTHOR]

To realize the clean and efficient resource utilization of sewage sludge (SS) and coal slime (CS), single-component and coupled fuels were analyzed. The micro-characteristics of combustion products were analyzed using multiple characterization means. The structure–activity relationship between the physicochemical properties and the mercury emission characteristics of SS and CS during the complex and changeable co-combustion process was established. The influence of coupling multiparameter conditions on the mercury emission process was revealed along with the combustion characteristics and evolution process using a distributed activation energy model. The results showed that α-HgS, HgSO4 and HgO with α-type hexagonal structures are the main forms of inorganic mercury compounds contained in SS and CS. The pyrolysis and combustion process of the sample can be divided into three stages. In the SS combustion process, the activation energy increases first and then decreases with increasing conversion rate α, and the activation energy of CS shows a U shaped trend distribution. For the influence of O2 on the combustion and mercury emission process, a critical concentration exists between O2 concentrations of 5% and 7%, which dominates the pyrolysis and heterogeneous combustion of carbonaceous substances and volatiles. When the temperature is above 750 °C, the Boudouard gasification reaction occurs directly between CO2 and the sample in the semicoke state, promoting combustion and mercury emission processes. Due to the strong interaction between the SS and CS, the mercury emission during the co-combustion process of the coupled fuel is inhibited and promoted at 400–500 °C and 500–600 °C, respectively. The iron mineral components and fixed carbon in the sample play a catalytic role during the decomposition process of mercury-containing compounds that are difficult to decompose. [ABSTRACT FROM AUTHOR]

Cement production is the third largest source of nitrogen oxides (NOx), an air pollutant that poses a serious threat to the natural environment and human health. Reducing NOx emissions from cement production has become an urgent issue. This paper aims to explore and investigate more efficient denitrification processes to be applied in NOx reduction from precalciner. In this study, firstly, the flow field, temperature field, and component fraction in the precalciner are studied and analyzed using numerical simulation methods. Based on this, the influence of the reductant injection height and amount on the SNCR was studied by simulating the selective non-catalytic reduction (SNCR) process in the precalciner. The effect of natural gas on the NOx emissions from the precalciner was also investigated. The simulation results showed that, with the increase in height, the NOx concentration in the precalciner decreased, then increased, then decreased, and then increased again. The final NOx concentration at the exit position was 531.33 ppm. In the SNCR denitrification process, the reductant should be injected in the area where the precalciner height is 26–30 m so that the reductant can fully react with NOx and avoid the increase of ammonia escape. The NSR represents the ratio of reductant to NOx, and the results show that the larger the NSR is, the higher the denitrification rate is. However, as the NSR approaches 2, the denitrification rate slows down and the ammonia escape starts to increase. Therefore, according to the simulation results, the NSR should be kept between 1 and 1.6. The denitrification rate reached the maximum value of 42.62% at the optimal condition of 26 m of reductant injection height and 1.6 of NSR. Co-firing of natural gas with pulverized coal can effectively reduce the NOx generation in the furnace. The denitrification rate reached the maximum value of 32.15% when the natural gas injection amount was 10%. The simulation results of natural gas co-combustion and SNCR combined denitrification showed that combined denitrification was better than natural gas co-combustion or SNCR denitrification. Under the condition of NSR of 1 and natural gas injection of 10%, the denitrification rate increased by 29.83% and 31.64% compared to SNCR-only or co-combustion-only denitrification, reaching 61.98%, respectively. Moreover, less reductant is used in co-denitrification, so the problem of excessive ammonia emissions can be avoided. The results of this study provide useful guidance for denitrification process development and NOx reduction in cement production. [ABSTRACT FROM AUTHOR]

In this study, combustion behaviours of blends prepared from 2.18 mm mean size lignite and hazelnut shell particles in specific proportions were investigated using a vertical pre-heated furnace system through which air was flowing upwards by natural convection. The results revealed that the ignition time of the blends approached those of hazelnut shell with temperature and showed certain interactions of the two materials during the volatiles combustion period. Combustion time generally complied with volatiles and carbon combustion rates of the two materials and their blends. Carbon combustion time decreased with temperature and hazelnut ratio, and implied some interactions of the materials. Although any effect of initial furnace temperature and hazelnut ratio of the blends on the NOx emissions was not clearly seen, SO2 emission levels depended on these factors. [ABSTRACT FROM AUTHOR]

Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Co-firing rice husk (RH) and coal with carbon capture using oxy-combustion presents a net carbon negative energy production opportunity. In addition, the high fusion temperature of the non-sticky, silica rich, RH can mitigate ash deposition as well as promote shedding of deposits. To identify the optimum operating conditions, fuel particle sizes, and blend ratios that minimize ash deposition, a Computational Fluid Dynamic methodology with add-on ash deposition and shedding models were employed to predict outer ash deposition and shedding rates during co-combustion of coal/RH in AIR and O2/CO2 (70/30 vol%, OXY70) oxidizer compositions. After ensuring that the fly-ash particle size distributions and particle Stokes numbers near the deposition surface were accurately represented (to model impaction), appropriate models for coal ash and RH ash viscosities that were accurate in the temperature region (1200–1300 K) of interest in this study were identified. A particle viscosity and kinetic energy (PKE) based capture criterion was enforced to model the ash capture. An erosion/shedding criterion that takes the deposit melt fraction and the energy consumed during particle impact into account was also implemented. Deposition rate predictions as well as the deposition rate enhancement (OXY70/AIR) were in good agreement with measured values. While the OXY70 scenario was associated with a significant reduction (60%–70%) in flue gas velocities, it also resulted in larger fly-ash particles. As a result, the PKE distributions of the erosive RH ash were similar in both scenarios and resulted in similar shedding rates. [ABSTRACT FROM AUTHOR]

An experimental study of the ignition and combustion processes of coal-water slurry (CWS) droplets based on coal enrichment waste in a high-temperature oxidizer at 650–850 °C with a syngas addition was carried out. The fuel slurry was a mixture of finely dispersed solid combustible particles (coal sludge, 10–100 µm in size) and water. The syngas was a product of biomass pyrolysis and two waste-derived fuels in a laboratory gasifier. Composition of the syngas was controlled by a precision analytical gas analyzer. The feasibility of co-firing CWS with syngas was experimentally established. Under such conditions, the CWS droplets ignition process was intensified by 15–40%, compared to fuel combustion without the addition of syngas to the combustion chamber. The greatest positive effect was achieved by adding the gas obtained during the biomass pyrolysis. The ignition delay times of CWS droplets are 5.2–12.5 s versus 6.1–20.4 s (lower by 15–39%) when ignited in a high-temperature medium without adding syngas to the combustion chamber. Based on the results obtained, a concept for the practical implementation of the CWS combustion technology in a syngas-modified oxidizer medium is proposed. [ABSTRACT FROM AUTHOR]

Cofiring of coal slime in existing utility boilers is a promising approach to the disposal of coal slime. However, reports about cofiring coal slime with anthracite in the down-fired utility boiler are still few. This work presents a comprehensive study on the combustion characteristics, slagging potential, and NOx emissions of cofiring coal slime and anthracite through lab-scale experiments, numerical simulations, and full-scale industrial measurements in a 600MW down-fired utility boiler. The lab-scale experiments show combustion interactions between anthracite and coal slime, which have both a promotive effect on the ignition of anthracite and inhibitive effect on the combustion and burnout of anthracite. Especially, the inhibitive effect is greater than the promotive effect when the blending ratio of coal slime is above 5%. The addition of coal slime can effectively improve the ash fusion temperature of blended samples. In addition, simulations and full-scale industrial measurements of anthracite cofiring with coal slime are performed in a down-fired utility boiler. The results show that as the blending ratio of coal slime increases, the carbon content in fly ash increases and the boiler efficiency and NOx emissions decrease. A 5% ratio is validated to be a reasonable cofiring ratio of coal slime in the actual operation without no slagging phenomenon. These results provide more insights into the cofiring behavior of coal slime and anthracite and guide the application of blending coal slime in a down-fired boiler. [ABSTRACT FROM AUTHOR]

Incineration is an important method of recycling municipal solid waste (MSW). As an industrial waste, leather has a higher calorific value and more combustible components than MSW. The blending of leather can make up for the high moisture content and insufficient calorific value of MSW, providing a good solution to reduce the capacity of MSW and industrial waste. This study predicts the effect of blending combustion by means of numerical simulation; the effects of leather blending ratio, the ratio of primary air and secondary air, total air volume, and fuel feed rate were analyzed. The results showed that the appropriate increase of blending ratio improves the furnace chamber temperature, and the best blending amount of leather is approximately 10%. The best primary and second air ratio is 0.72:0.28. Insufficient airflow caused inadequate combustion, and excessive airflow reduced the furnace temperature. The feed volume in the range of 500 to 550 t/d had a good burning effect. [ABSTRACT FROM AUTHOR]

This study presents the results of concentrations of rare earth elements and yttrium (REY), uranium (U), and thorium (th) in ashes from combustion/co-combustion of biomass (20%, 40%, and 60% share) from the agri-food industry (pomace from apples, walnut shells, and sunflower husks) and hard coal. The study primarily focuses on ashes from the co-combustion of biomass and hard coal, in terms of their potential use for the recovery of rare earth elements (REE), and the identification of the sources of these elements in the ashes. Research methods such as ICP-MS (inductively coupled plasma mass spectrometry), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy with quantitative X-ray microanalysis) were used. The total average content of REY in ash from biomass combustion is 3.55-120.5 mg/kg, and in ash from co-combustion, it is from 187.3 to 73.5 mg/kg. the concentration of critical REE in biomass combustion ash is in the range 1.0-38.7 mg/kg, and in cocombustion ash it is 23.3-60.7 mg/kg. In hard-coal ash, the average concentration of Rey and critical REY was determined at the level of 175 and 45.3 mg/kg, respectively. In all samples of the tested ashes, a higher concentration of th (0.2-14.8 mg/kg) was found in comparison to U (0.1-6 mg/kg). In ashes from biomass and hard-coal combustion/co-combustion, the range of the prospective coefficient (Coutl) is 0.66-0.82 and 0.8-0.85, respectively, which may suggest a potential source for REE recovery. On the basis of SEM-EDS studies, yttrium was found in particles of ashes from biomass combustion, which is mainly bound to carbonates. The carriers of REY, U, and th in ashes from biomass and hard-coal co-combustion are phosphates (monazite and xenotime), and probably the vitreous aluminosilicate substance. [ABSTRACT FROM AUTHOR]

As a major carbon-emitting country, China has considerable potential for carbon capture and storage (CCS) applications, but economics is critical for CCS deployment. In this study, the levelized cost of electricity (LCOE) at province level was calculated for operational coal-fired power plants after post-combustion carbon capture (CC) retrofitting. The costs of captured CO2 and avoided CO2 were then compared. The economics of CC-retrofitted coal-fired power plants co-firing with biomass (BECC) were also analyzed. CC retrofitting is economical in North and Northwest China (except Qinghai) where coal prices are low. However, BECC retrofit is more suitable for coal-fired power plants in Central China where biomass prices are low. Therefore, the variation in the resource conditions among provinces should be considered when promoting CC and BECC retrofits. Compared with other power sources, coal-fired power generation becomes much more expensive after retrofits. We calculated the carbon price and capacity subsidy intensity that could support the retrofit of coal units. Effective carbon price should be 142.44–406.06 CNY/t for retrofits, and the capacity subsidy intensity ranges from 175.14–721.52 CNY/kW. The current carbon market and capacity market are not sufficiently developed to support retrofitting. The development of the carbon market with effective carbon price signals and proper power market mechanisms is critical to the rollout of CCS in China. [ABSTRACT FROM AUTHOR]

The combustion of lignite, biomass (pine cones), and their mixtures (in different proportions) is investigated by simultaneous thermal analysis. In the analysis, ~6-mg samples are heated in an oxidative atmosphere at 20°C/min, with an air flow rate of 50 mL/min. The thermal characteristics and elemental composition of the solid fuels are determined by standard methods. Analysis of the heating of the fuel mixtures and their components indicates that combustion occurs in different temperature ranges: 258–549°C for lignite; 220–503°C for pine cones; and 230–536°C for their mixtures (depending on the proportions of the components). The coke residue of the pine cones ignites at 302°C, which is 58°C lower than the value for lignite (360°C). Adding 25–75% biomass to lignite lowers the ignition temperature of the mixture by 21–56°C. Predicting the basic combustion characteristics of the mixture by appropriate summation of the components' characteristics is possible if the biomass content is no more than 25%. With higher biomass content, the influence of the components on the combustion characteristics of the mixture is nonproportional, over a broad temperature range [ABSTRACT FROM AUTHOR]

The operational parameters of monoethanolamine (MEA)-based carbon capture were investigated and optimized based on 300 MW e co-firing power plant. The representative coal and biomasses (peanut shell, rice straw and rice husk) were employed as co-firing fuels by quantitative analysis. The stripper pressure is determined as 1.9 bar and CO 2 capture rate no more than 90% is preferred for relatively low energy consumption, and the optimal CO 2 loadings in lean solution is mainly 0.22. The key material and energy performances of the main equipment and the carbon capture system at the optimal operating conditions were comprehensively discussed. The addition of the biomass leads to more CO 2 captured as well as more thermal consumption. The optimal specific thermal requirement for rice husk-firing reaches the lowest, 3.39 MJ/kg CO 2 for 90% CO 2 removal. To capture CO 2 from flue gases deriving from biomass-contained fuels is more energy efficient compared to that from pure coal. The carbon capture system contributes ∼18–22% total energy penalty compared with the case without carbon capture system. The study devotes to the application of integrated low energy penalty carbon capture technology (CCT) with biomass co-firing technology. [ABSTRACT FROM AUTHOR]

Ammonia (NH3), as a derivative of hydrogen and energy carrier, is regarded as a low-carbon fuel provided that it is produced from a renewable source or a carbon abated process of fossil fuel. Co-firing ammonia with coal is a promising option for pulverized coal-fired power plants to reduce CO2 emission. Applying the co-firing in an existing pulverized coal-fired boiler can achieve satisfying combustion performance in the furnace but may affect the boiler performance. In the present work, a thermal calculation method was employed to evaluate the impact of ammonia co-firing on the boiler performance of an existing 600 MW supercritical utility boiler, covering the co-firing ratio range up to 40% (on heat basis). The calculations indicated that, as compared to sole coal combustion, co-firing ammonia changed the volume and composition and consequently the temperature and heat transfer characteristics of the flue gas. These resulted in increased variations in the heat transfer performance of the boiler with increasing of the co-firing ratio. The evaluations revealed that co-firing up to 20% ammonia in the existing boiler is feasible with the boiler performance not being considerably affected. However, the distribution of the heat transferred from the flue gas to boiler heat exchangers is significantly deteriorated at higher ratios (30% and 40%), resulting in over-temperature of the superheated steam, under-temperature of the reheated steam and considerable reduction in boiler thermal efficiency. It implies retrofits on the heat exchangers required for accommodating higher ratio co-firing in the existing boiler. The comparison study showed that co-firing 20% ammonia provides a superior boiler performance over co-firing 20% biomass producing gases and blast furnace gas. [ABSTRACT FROM AUTHOR]

The technical supply potential of biomass and the associated greenhouse gas (GHG) emissions are widely studied in the literature. However, relatively few studies have examined the role of biomass co-firing for future electricity in China by integratedly considering the economic supply potential and GHG effects. To fill this gap, we choose the Jiangsu Province in China as a case study and build up a partial equilibrium model with multiple agricultural commodities. Using this model combined with a life cycle assessment, we jointly determine the economic potential of the biomass supply for a biomass co-firing purpose and social benefits, including the agricultural producers' surplus and GHG mitigation potential. The simulation incorporates the county-level biomass market of various crop residues as well as endogenous crop prices and transportation costs. We find that 0.7–12.5 M MT of residue-based biomass are economically viable for co-firing in coal-based power plants (up to 20%) at biomass prices between USD 50 and USD 100/MT. The net GHG savings achieved at these biomass prices are from 3.2 to 59 M MTCO2e. Our findings indicate that biomass co-firing with coal in power plants would be a feasible low-carbon energy transition pathway if the biomass price is above USD 50/MT. In addition to biomass prices, other factors such as crop yields, production costs of residues, and transportation costs are found to be impactful on the economic viability of biomass and GHG savings. Our results can inform policy to develop localized carbon reduction strategies in provinces with abundant biomass resources and a high share of coal-fired electricity. [ABSTRACT FROM AUTHOR]

As an industrial solid waste, the discharge of a large amount of red mud (RM) causes serious environmental problems; thus, a large proportion of RM co-combustion has been proposed to solve the consumption problem. In this paper, an experiment with various proportions of RM co-combustion was conducted on a 0.2 t/h circulating fluidized bed (CFB) boiler. Desulfurization performance, combustion characteristics, and ash deposition characteristics were analyzed, especially under the large proportional co-combustion conditions. As the study results showed, the desulfurization efficiency was positively correlated with the RM co-combustion proportion. When the RM co-combustion proportion reached 50%, the desulfurization efficiency was over 94%. After a period of cyclic combustion, the highest desulfurization efficiency exceeded 99.5%. The smaller size of RM was beneficial to improve the combustion efficiency and the combustion stability. However, a large area of sintering formed on the top of the heating surface in the furnace, which was lighter than the sintering of high alkali fuels such as Zhundong coal. Meanwhile, the content of sulfates, such as Na2SO4 and CaSO4, in the ash increased, which clearly proves that RM has the desulfurization effect. Therefore, a large proportion of co-combustion could meet the requirements of in-situ desulfurization and realize the resource utilization of RM. [ABSTRACT FROM AUTHOR]

The co-combustion of dry coal and sludge was carried out in a self-built laboratory scale fluidized bed furnace. We used FTIR spectroscopy, high-resolution gas chromatography, high-resolution mass spectrometry, and XRF to capture and dynamically observe the flue gas fly ash and bottom ash. The sludge sample was taken from a municipal sewage treatment plant and its mixing ratio was below 20%. The temperature distribution of the furnace was observed and the emissions of the main gaseous pollutants such as SO2, NOx, and dioxins were measured in the combustion process. The heavy metal contents of fly ash and bottom ash were later detected to analyze the migration characteristics. The results showed that all of the gaseous pollutants measured increased linearly with the sludge mixing ratio. However, it could also meet the 1 metal content of bottom ash and fly ash did not change much. Through the elaboration of the above points, this study can provide guidance for future research on the co-combustion of coal boiler sludge and suggest favorable conditions for the co-combustion of coal boiler sludge. [ABSTRACT FROM AUTHOR]

Y 2.5- x Bi 0.5 Al x Fe 5 O 12 (YIG-Al x) ceramics have been synthesized at 1175 ℃ by the solid-state reaction method. The effects of the co-doped Bi3+, Al3+ ions on the phases, micromorphology, and dielectric and magnetic properties of the yttrium iron garnets (YIG) were investigated. Excessive introduction of Al3+ ions led to the collapse of the YIG lattice and precipitation of the Bi3+ and Fe3+ ions; while moderate Al3+ doping improved the dielectric properties, but not the saturation magnetization. The YIG-Al 0.2 ceramics proved to have particularly good electromagnetic properties (ε r = 18.34 ± 0.05@11.19 GHz, tan δ = 3.09 ± 0.55 × 10−4, M s = 19.82 ± 0.55 emu/g). Additionally, tightly bonded Y 2.3 Bi 0.5 Al 0.2 Fe 5 O 12 /Ni 0.8 Zn 0.2 Fe 2 O 4 (YIG-Al 0.2 /NZF) composite substrates were prepared by co-firing at 1175 ℃. The composite substrates exhibited superior electromagnetic properties (YIG-Al 0.2 : ε r = 18.37 ± 0.05@11.15 GHz, tan δ = 3.08 ± 0.55 × 10−4, M s = 21.09 ± 0.55 emu/g; NZF: M s = 67.5 ± 0.55 emu/g), which were slightly affected by the diffusion of Ni and Zn from the NZF. Our findings show that YIG-Al 0.2 /NZF substrates have great potential for use as RF band circulators. • The YIGs appropriately doped with Bi3+-Al3+ ions has good dielectric properties. • The co-pressed and co-fired techniques were applied to the composite substrates. • The YIG-Al 0.2 /NZF ferrites composite substrates possess high electromagnetic properties. • Diffusion of Fe3+ ions of the YIG-Al 0.2 /NZF ferrites composite substrates was small. [ABSTRACT FROM AUTHOR]

The utilization of co-firing (coal-biomass) in existing coal-fired power plants (CFPPs) is the fastest and most effective way to increase the renewable energy mix, which has been dominated by pulverized coal (PC) boilers, particularly in the Indonesian context. This study aims to investigate the technical and economic aspects of co-firing by conducting a pilot project of three PC boiler plants and capturing several preliminary figures before being implemented for the entire plants in Indonesia. Various measured variables, such as plant efficiency, furnace exit gas temperature (FEGT), fuel characteristic, generating cost (GC), and flue gas emissions, were identified and compared between coal-firing and 5%-biomass co-firing. The result from three different capacities of CFPP shows that co-firing impacts the efficiency of the plant corresponding to biomass heating value linearly and has an insignificant impact on FEGT. Regarding environmental impact, co-firing has a high potential to reduce SO2 and NOx emissions depending on the sulfur and nitrogen content of biomass. SO2 emission decreases by a maximum of 34% and a minimum of 1.88%. While according to economic evaluation, the average electricity GC increases by about 0.25 USD cent/kWh due to biomass price per unit of energy is higher than coal by 0.64×10-3 USD cent/kcal. The accumulation in the one-year operation of 5%-biomass co-firing with a 70% capacity factor produced 285,676 MWh of green energy, equal to 323,749 tCO2e and 143,474 USD of carbon credit. The biomass prices sensitivity analysis found that the fuel price per unit of energy between biomass and coal was the significant parameter to the GC changes. [ABSTRACT FROM AUTHOR]

In this research, the upgrading of agro-industrial wastes was investigated by using the torrefaction pretreatment technique. Two types of biomass waste, including sugarcane bagasse (SBG) and palm kernel shell (PKS), were used as raw materials. The operating conditions, i.e., torrefaction temperature and residence time, are between 225–300 °C and 30–90 minutes. The findings show that, in terms of mass yield and calorific value of the solid product, the torrefaction temperature is a more sensitive parameter than the residence time. By increasing the torrefaction temperature from 225 to 300 °C, the mass yields are dropped in the range of 28.79–31.57 wt.% and 28.00–29.88 wt.%, while the effect of holding time exhibits the mass yield decreasing only 3.12–5.90 wt.% and 1.53–3.41 wt.%, for SBG and PKS torrefaction, respectively. In terms of calorific value, higher heating values increase as torrefaction severity increases, varying in the range of 0.29–2.84 MJ/kg, with torrefaction temperature as the dominant factor. Regarding the calorific value, energy yield, energy gain, and energy-mass co-benefit index, the optimal operating conditions for SBG and PKS torrefactions are the same condition as 275 °C for 90 minutes. SBG and PKS bio-coals obtained from torrefaction are promising solid fuels with high calorific value (about 23 MJ/kg), with an energy yield of 73.93–77.41%, relative to coal that could be further utilized for co-firing in thermal power plants. [ABSTRACT FROM AUTHOR]

Results of experimental studies of joint pyrolysis processes of a fairly typical and widely used in Russia and Poland 3B grade lignite and wood (sawdust of pine wood) are provided. The results were performed in order to substantiate the previously formulated hypothesis about the mechanism of suppression of sulfur oxides in the combustion products of such mixed fuels. Conclusions on the mechanism of SOx suppression were made after comparing the analysis results of the elemental composition of the initial lignite, wood, and ash remaining after the total completion of the studied mixtures pyrolysis processes, as well as X-ray phase analysis of the ash composition. It was found that the proportion of calcium and aluminum sulfates is higher in the solid pyrolysis products of mixtures of crushed coal and wood compared to the ash of homogeneous coal. Practical significance of the performed studies is that the obtained results of the experiments allow to justify the possibility of using wood as a part of mixed fuels based on 3B grade lignite as an additive that significantly reduces the yield of sulfur oxides during combustion of such fuels in the furnaces of steam and hot water boilers. It has been experimentally established that during high-temperature decomposition of two-component fuels based on 3B lignite in a mixture with fine wood biomass, the effect of reduction of sulfur oxide concentration in gaseous pyrolysis products of such mixtures is obtained due to the formation of calcium and aluminum sulfates in the ash of mixed fuels as a result of chemical reactions between gaseous and solid pyrolysis products of lignite and wood with participation of water vapor. [ABSTRACT FROM AUTHOR]

Co-combustion of coal and biomass is a sustainable and cost-operative choice for generating power. Biomass assets such as rice husk play a vital part in decreasing the concentration of discharge gases, while usage in the co-combustion approach. This research concentrated on the physicochemical and emission investigation of coal and rice husk blends for emission reduction. Thar coal comprises higher content of moisture and sulfur while lower in volatile matter and ash. However, rice husk is higher in volatile matter, and lower in moisture and sulfur with higher ash. The blends of coal with rice husk in weight fractions 90:10 (CRh-1), 80:20 (CRh-2), and 70:30 (CRh-3) were also characterized. The study reveals that CRh-1 contains 1.39%, CRh-2 contains 1.17%, and CRh-3 contained 0.99% elemental sulfur respectively after the blend. Flue gases analysis from muffle furnace stack showed that coal-rice husk blends 70:30% (CRh-3) were found to be feasible from the energy production point of opinion. Overall, NOx and SOx discharges were found to decline from 89 ppm (CRh-1) to 34 ppm (CRh-3) and 828 ppm (CRh-1) to 169 ppm (CRh-3) respectively by increasing the blending fraction from 10 to 30%. The study has concluded that rice husk blending would be a beneficial choice to reduce SOx and NOx discharges in the combustion of Thar coal for efficient, sustainable, and environmentally friendly combustion for energy production and support to fulfill the requirement of UN Environment SDG 7 clean energy goal. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic brought a period of high consumption of protective masks and an increase in their waste. Therefore, it was necessary to look at possibilities for their disposal. This article is focused on the disposal of FFP2 masks in the form of pellets blended with sawdust. Further, their ash melting behavior was observed. The method of ash preparation can impact the resulting values of melting temperatures. Therefore, this article investigates the resulting values of ash melting temperatures determined during different ash preparations, such as temperatures (550 °C and 815 °C) and ash size (non-sifted, smaller than 50 µm and 100 µm). All measured deformation temperatures were higher than 1100 °C and even higher than 1200 °C for some samples. Moreover, the presence of FFP2 masks in pellets only insignificantly affected the values of melting temperatures compared to pure wood pellets. The measured values also showed that increasing the temperature of ash preparation from 550 to 815 °C can increase the resulting values of melting temperature. The most significant proportion of the fraction size on the resulting melting temperatures was observed for beech with 5% and 10% of masks at an ash temperature of 550 °C and for spruce with 10% of masks at an ash temperature of 815 °C. [ABSTRACT FROM AUTHOR]

Sampling and 14C detection of biomass are now essential steps to ensure the accuracy of the 14C method, but they require additional time and economic investment. When there are multiple types of biomass fuels, it is not possible to guarantee the uniformity of sampling. The 14C activity of biomass fuels exhibits variability, and this value significantly impacts the precision of the 14C method. Therefore, this study aims to investigate the influencing factors of 14C activity in biomass fuels. It also provides predicted values of 14C activity for different types of biomass fuels for each year from 2020 to 2030. Additionally, this study discusses the potential blending ratio measurement errors that may arise due to the uncertainties of the predicted values. The reduction in the 14C activity of biomass fuels can occur due to the utilization of fossil fuels, human activities, and the photosynthesis mode of C3 plants. This study presents a prediction method for determining the reduction factor. The other component of the prediction methodology involves determining the original 14C activity of biomass fuels. The 14C activity of the annual biomass is equal to the 14CO2 activity (the 14C activity of CO2) of the surrounding environment, and it experiences a decline of 0.355 pMC/year. The 14C activity has ranges of five types of perennial biomass fuels, including wood chips and branches, bark, leaves, wasted furniture, and abandoned building wood, for the time period between 2020 and 2030, are 97.34~102.84, 96.35~106.27, 96.35~102.64, 111.00~118.60, and 111.32~129.47 pMC, respectively. Based on these, this study introduces a new formula for calculating blending ratios, which enhances the current methodology. The calculation errors of blending ratios caused by the uncertainties of the predicted values are generally negligible, with the exception of wasted furniture and construction wood. The annual decrease in the blending ratio calculation error, caused by the uncertainty associated with the predicted value, can be observed. This study aims to reduce the implementation time and economic cost of the 14C method while ensuring the accuracy of biomass blending ratio detection.

Bio-SRF based on livestock waste has low heating value and high moisture content. The concentration of toxic gases such as SOx, NOx, and HCl in the flue gas is changed according to the composition of fuel, and it has been reported. Therefore, the study of fuel combustion characteristics is necessary. In this study, we investigated combustion characteristics on the blended firing of coal and Bio-SRF (bio-solid refused fuel) made from livestock waste fuel in CFBC (circulating fluidized bed combustor). The raw materials for manufacturing Bio-SRF include agricultural waste, herbaceous plants, waste wood, and vegetable residues. Bio-SRF, which is formed from organic sludge, has a low heating value and a high moisture content. Bio-SRF of livestock waste fuel is blended with different ratios of coal based on heating values when coal is completely combusted in CFBC. In the result of experiment, the combustor efficiency of calculated unburned carbon concentration in the fly ash shows 98.87%, 99.04%, 99.64%, and 99.71% when the multi co-combustion ratio of livestock waste fuel increased from 100/0 (coal/livestock waste) to 70/30 (coal/livestock waste). In addition, the boiler efficiency is shown to be 86.23%, 86.30%, 87.24% and 87.27%. Through the experimental results, we have identified that co-combustion of livestock waste fuel does not affect boiler efficiency. We have systematically investigated and discussed the temperature changes of the internal combustor, compositions of flue gases, solid ash characteristics, and the efficiency of combustion and of the boiler during co-combustion of coal and Bio-SRF. [ABSTRACT FROM AUTHOR]

When burning fuel in grate furnaces, supplying the right amount of air to them is as important as the method of air supply. In a furnace with a fixed grate, the supply method of primary air is determined by the distribution of the supplied air stream over time, and in a furnace with a movable grate, the said method involves the distribution of the stream along the active length of the grate. The need to account for air distribution is attributable to complex processes that occur during the combustion process. The paper describes experimental studies aimed at determining the influence of the distribution of the supplied primary air on the emission of CO2, CO, SO2, NOx, and on the content of combustible parts in the slag. In all cases, the total amount of primary air supplied to the process as well as other process control parameters was identical, and only the distribution of primary air was different. The paper proposes the use of a generalized function to describe the distribution of air, defined by its total demand and the relative time R that fuel remains on the grate until the maximum air stream is obtained. The quantity R was accepted at the value ranging from 1/6 to 2/3. With the rise of R, the emissions of CO2, CO, and SO2 increased by 53%, 125%, and 27%, respectively, and the emissions of NOx and the share of combustibles in the slag decreased by 12% and 79%, respectively. [ABSTRACT FROM AUTHOR]

The South Korean government plans to gradually change existing power generation from natural gas (NG) to hydrogen co-fired with NG to help abate emissions of greenhouse gases (GHGs). This research aims to explore people's additional willingness to pay (AWTP) for consuming one kWh of electricity generated from a mixture of 35% hydrogen and 65% NG compared to electricity generated from 100% NG. Contingent valuation (CV) was applied to obtain data on the AWTP. A CV survey of 1000 randomly chosen people was conducted to obtain data, a one-and-one-half-bounded model was adopted to elicit the AWTP from interviewees, and a spike model was used to analyze the AWTP observations with zeros. The average AWTP was obtained as KRW 24.3 (USD 0.022) per kWh. Since the electricity price was KRW 107.9 (USD 0.096) per kWh, the value that people place on co-firing, which means the sum of the price and the AWTP, was KRW 132.2 (USD 0.118) per kWh. Because the total cost of the power supply for hydrogen co-fired with NG is KRW 145.7 (USD 0.130) per kWh, a subsidy of at least KRW 13.5 (USD 0.012) per kWh must be provided to encourage co-firing to mitigate GHG emissions. [Display omitted] • Co-firing of a mixture of 35% hydrogen and 65% natural gas (NG) is considered. • The public perspective on co-firing is explored, adopting contingent valuation. • Additional willingness to pay (AWTP) for co-firing is examined. • AWTP is obtained as KRW 24.3 per kWh, but the price increases by KRW 13.5 per kWh. • A subsidy of at least KRW 13.5 per kWh is needed to encourage co-firing. [ABSTRACT FROM AUTHOR]

Li–CO2 batteries possess exceptional advantages in using greenhouse gases to provide electrical energy. However, these batteries following Li2CO3-product route usually deliver low output voltage (<2.5 V) and energy efficiency. Besides, Li2CO3-related parasitic reactions can further degrade battery performance. Herein, we introduce a soluble binuclear copper(I) complex as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries. The Li–CO2 battery using the copper(I) complex exhibits a high electromotive voltage up to 3.38 V, an increased output voltage of 3.04 V, and an enlarged discharge capacity of 5846 mAh g−1. And it shows robust cyclability over 400 cycles with additional help of Ru catalyst. We reveal that the copper(I) complex can easily capture CO2 to form a bridged Cu(II)-oxalate adduct. Subsequently reduction of the adduct occurs during discharge. This work innovatively increases the output voltage of Li–CO2 batteries to higher than 3.0 V, paving a promising avenue for the design and regulation of CO2 conversion reactions. Li–CO2 batteries following Li2CO3-product route suffer from low output voltage and severe parasitic reactions. Herein, a soluble binuclear copper(I) complex is introduced as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries, which increases their output voltage to higher than 3.0 V. [ABSTRACT FROM AUTHOR]

Biomass from agricultural production is a renewable energy source with a high-volatile content. Semicoke (SC) and gasification residual carbon, which are ultralow volatile carbon-based fuels (LVFs), are by-products of the coal chemical industry, which are over capacity and urgently need to be cleanly and effectively consumed. Biomass and LVFs exhibit complementary fuel characteristics, particularly the volatile content, which can potentially be coprocessed efficiently. Furthermore, oxyfuel combustion technology can not only realize carbon dioxide (CO2) capture and benefit from carbon neutrality, but also effectively reduce NOx emissions. The cocombustion of biomass and ultralow volatile fuel under oxyfuel conditions can both use individual benefits and effectively control pollutant emissions. However, the cofiring characteristics and interaction mechanisms of LVF with biomass in an oxyfuel atmosphere are yet to be fully understood. In this study, three ultralow volatile fuels and one typical biomass were selected to explore the oxyfuel cocombustion characteristics via thermogravimetric experiments. The experimental results indicated that blending with wheat straw (WS) improved the overall combustion performance, the ignition point was close to that of WS, and the burnout temperature was close to the average value of the two individual fuels. An increase in the oxygen content can effectively enhance the combustion feature of ultralow volatile fuels while it has little effect on the burnout performance of biomass. In the presence of high-content CO2 , the decomposition of carbonate in ultralow volatile fuel is impeded and the decomposition temperature is slightly increased. The present investigation can promote the efficient co-utilization of inferior LVFs and biomass, which also benefits CO2 capture, carbon neutrality, and even negative carbon emissions. [ABSTRACT FROM AUTHOR]

This study examines the fireside corrosion of FeCrAl, NiCr, NiCrAlY and A625 coatings applied by 'high velocity oxy fuel'(HVOF) and exposed to simulated biomass firing conditions (gas composition CO2, N2, SO2 and HCl). The coatings and a typical base steel alloy (T92) were exposed to simulated conditions at 600 °C for 1000 h in a laboratory scale furnace. Samples were coated with a potassium chloride deposit. Samples were then cold mounted in a low-shrinkage epoxy resin and then cross-sectioned. Corrosion was assessed by dimensional metrology comparing the coating thickness change of the samples. The cross-sections of the 'worst' and 'best' coatings were examined. Results show that all but one coating (HVOF NiCr) outperformed the T92 alloy. No coating composition or method was conclusively better. Evidence of Cr depletion as well as the formation of a sulphidation layer have been found in the exposed samples with coatings. The formation of a K2SO4 layer has also been observed on all coated specimens. [ABSTRACT FROM AUTHOR]

The presented work concerns experimental research of a spark-ignition engine with variable compression ratio (VCR), adapted to dual-fuel operation, in which co-combustion of ammonia with hydrogen was conducted, and the energy share of hydrogen varied from 0% to 70%. The research was aimed at assessing the impact of the energy share of hydrogen co-combusted with ammonia on the performance, stability and emissions of an engine operating at a compression ratio of 8 (CR 8) and 10 (CR 10). The operation of the engine powered by ammonia alone, for both CR 8 and CR 10, is associated with either a complete lack of ignition in a significant number of cycles or with significantly delayed ignition and the related low value of the maximum pressure p max. Increasing the energy share of hydrogen in the fuel to 12% allows to completely eliminate the instability of the ignition process in the combustible mixture, which is confirmed by a decrease in the IMEP uniqueness and a much lower p max dispersion. For 12% of the energy share of hydrogen co-combusted with ammonia, the most favorable course of the combustion process was obtained, the highest engine efficiency and the highest IMEP value were recorded. The conducted research shows that increasing the H 2 share causes an increase in NO emissions, for both analyzed compression ratios. • For 8 and 10 compression ratios, 12% of hydrogen energy share co-fired with ammonia provided the most favorable. • The engine powered with ammonia alone results in a very high IMEP uniqueness (COV IMEP >5%). • Compared to powering engine by ammonia, 12% of H2 fraction causes 2 times decrease of the ignition delay. • An increase in the proportion of hydrogen causes an increase in NO emissions. • The increase in H2 fraction burned with ammonia requires a reduction in the ignition timing. [ABSTRACT FROM AUTHOR]

The harmless disposal of spent cathode carbon blocks (SCCBs) has become an urgent issue in the primary aluminum industry, and the disposal of SCCBs by co-combustion in pulverized coal boilers is expected to be the most effective treatment method. A muffle furnace at 815 °C was used in this study to perform a co-combustion experiment of meager coal and SCCBs. The ash fusion characteristics (AFTs), microscopic morphology, and minerals composition of co-combustion ash were characterized. The interaction mechanism of different mineral components and the change in AFTs and viscosity-temperature characteristics were investigated using FactSage software. Results show that the change in the ash deformation temperature (DT) is correlated linearly with the SCCB addition ratio, whereas other characteristic temperatures exhibit a nonlinear relationship. The contents of SiO2, Al2O3, and Na2O collectively determine the DT in the ash, and the influence degree from high to low is in the order of SiO2, Na2O, and Al2O3. The phase diagram of Na2O–Al2O3–SiO2 is used to accurately predict the changing trend of the melting point of co-combustion ash. The ratio changes between refractory and fusible minerals in the ash, as well as the degree of low-temperature eutectic reaction between sodium- and calcium-containing minerals, are the main factors affecting the melting point of ash. When the blending amount of SCCBs is 5%, mostly complete combustion is achieved, and slagging does not occur easily. The optimal blending ratio of SCCBs is obtained using the co-combustion method from the aspect of AFTs and viscosity-temperature characteristics. This work lays a theoretical foundation for industrial application. [ABSTRACT FROM AUTHOR]

The pulverized coal-fired furnaces are expected to use co-firing with biomass for environmental reasons. Although the non-uniform ash deposits are formed on the furnace walls, the uniform deposits could be used for the analysis of the furnace operation. The objective of this investigation was determination of the uniform deposit thickness, used as a criterion for prediction of the sootblower activation moment in coal-biomass co-firing. The investigation comprised numerical simulations for uniform and non-uniform deposits to find the relative differences for the selected variables that were important for the sootblower activation: the mean wall fluxes and flame temperatures. The local thicknesses of the non-uniform deposits were determined by the gamma distribution for several mean and standard deviation values using the inversion method. The thicknesses of the uniform deposits were considered among the measures of central tendency: mode, mean, and median, of the non-uniform deposits. The mean was expected to provide the smallest relative differences, while the mode was excluded from further consideration after analysis of its values. The median was found to be better choice than the mean, as it provided smaller relative differences of the selected variables for the thick deposits, which were important for the sootblower activation. The method based on comparison of the uniform deposits for coal firing and those for the co-firing with biomass was proposed for the prediction of the sootblower activation moment. The method can be used for the selection of the operational regimes for coal-biomass co-firing. [ABSTRACT FROM AUTHOR]

With the rapid development of desulfurization process, how to efficiently utilize sintered desulfurized dust in the desulfurization process has always been a problem faced by a steel industry. In this paper, the physicochemical properties of Kubasi anthracite coal (RU), Shangwan bituminous coal (SW), and desulfurized dust (TL) were systematically studied by means of X-ray fluorescence spectrophotometer, scanning electron microscopy, and Raman spectroscopy. In addition, the combustion characteristics and mechanisms of anthracite, bituminous, and desulfurized dust mixtures were investigated by thermogravimetric analysis experiments. The results show that the particle size of TL is finer, the degree of graphitization of RU is higher, the combustibility of SW is better than that of RU, and the effects of TL addition on the combustion performance of RU and SW are different. The calculated results of combustion kinetics are in good agreement with the experimental results. With the addition of TL from 3 to 7 wt%, the activation energy of SW decreased from 44.00 to 37.30 kJ/mol. The results provide a theoretical basis for adding desulfurized dust to the blast furnace in the future. [ABSTRACT FROM AUTHOR]