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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]

In order to reduce global warming, new energy fuels that use waste biomass to replace traditional coal are rapidly developing. The main purpose of this study is to investigate the feasibility behavior of different biomass materials such as spent coffee grounds (SCGs) and spent tea grounds (STGs) as fuel during combustion and their impact on the environment. This study involves using fuel shaping and co-firing methods to increase the fuel calorific value and reduce the emissions of pollutants, such as NOX and SO2, and greenhouse gas CO2. The produced gas content was analyzed using the HORIBA (PG-250) laboratory combustion apparatus. The results indicate that, among the measured formed particles, SCG:STG = 8:2, 6:4, and 4:6 had the lowest post-combustion pollutant gas emissions. Compared to using only waste coffee grounds as fuel, the NOx emissions were reduced from 166 ppm to 102 ppm, the CO emissions were reduced from 22 ppm to 12 ppm, and the CO2 emissions were reduced from 629 ppm to 323 ppm. In addition, the emission of SO2, the main component of acid rain, was reduced by 20 times compared to the combustion of traditional fuels. The SO2 emission of five different proportions of biomass fuels was 5 ppm, which is much lower than that of traditional coal fuels. Therefore, SCG and STG mixed fuels can replace coal as fuel while reducing harmful gasses. [ABSTRACT FROM AUTHOR]

The study aimed to explore the effects of biomass co-firing of coal using acacia wood bark at circulating fluidized bed (CFB) boiler coal-fired power plant with 110 MWe capacity. The analysis focused on main equipment parameters, including the potential for slagging, fouling, corrosion, agglomeration, fuel cost, and specific environmental factors. Initially, coal and acacia wood bark fuel were blended at a 3% mass ratio, with calorific values of 8.59 MJ/kg and 16.59 MJ/kg, respectively. The corrosion due to chlorine and slagging potential when using wood bark was grouped into the minor and medium categories. The results showed that co-firing at approximately 3% mass ratio contributed to changes in the upper furnace temperature due to the variation in heating value, high total humidity, and a less homogeneous particle size distribution. Significant differences were also observed in the temperature of the lower furnace area, showing the presence of a foreign object covering the nozzle, which disturbed the ignition process. A comparison of the seal pot temperature showed imbalances as observed from the temperature indicators installed on both sides of boiler, with specific fuel consumption (SFC) increasing by approximately 0.17%. During the performance test, the price of acacia wood bark was 0.034 USD/kg, resulting in fuel cost of 0.023355 USD/kWh, adding 0.061 cent/kWh to coal firing cost. Despite co-firing, the byproducts of the combustion process, such as SO2 and NOx, still met environmental quality standards in accordance with government regulations. However, a comprehensive medium- and long-term impact evaluation study should be carried out to implement co-firing operations using acacia wood bark at coal-fired power plant. Based on the characteristics, such as low calorific value, with high ash, total moisture, and alkali, acacia wood bark showed an increased potential to cause slagging and fouling.

The problem of organic and non-economic LDPE plastic waste, which is abundant in the Singkawang City landfill, is accompanied by the reduced availability of coal as a fuel for steam power plants. Therefore, this study utilizes organic and plastic waste as biomass fuel that can be used in steam power plants using the co-firing method. This research aims to identify the characteristics, analyze the optimal composition based on SNI 8966:2021, and examine the influence of solid fuel composition. The research method used four composition variations: 100:0%, 95:5%, 85:15%, and 75:25. The best average water content, volatile matter, ash, fixed carbon, and calorific value were 4%, 60.67%, 11.33%, 2.67%, and 5,374.29 Kcal/kg, respectively. The characteristics of the solid fuel comply with SNI 8966:2021, except for the fixed carbon content. Based on the Kruskal-Wallis test, the fuel compositions for the characteristics of water content, volatile matter, ash, and calorific value are significantly different, with values of 0.035, 0.056, 0.041, and 0.016. Based on Spearman rank correlation analysis, water and ash contents decreased as the percentage of plastic increased, with correlation coefficients of -0.753 and -0.302. Meanwhile, the calorific value and volatile matter increased, with correlation coefficients of 0.811 and 0.972.

The primary energy source in developing countries, including Indonesia, is fossil energy. Therefore, evaluating the environmental impact of coal-fired steam power plants is crucial. Comprehensive scientific analysis is required to develop appropriate alternative measures. This research aims to analyze the life cycle impact of the coal power plant at the gate, including the coal yard, coal crusher, boiler, turbine, and generator, with the functional unit of 1 kWh of electricity produced. The analysis reveals the highest impact in the climate change potential category (1.40 × 10-1 kg CO2 eq/kWh), while the smallest impact was recorded in the Eutrophication potential category (7.55 × 10-4 kg PO4 eq/kWh), with no impact on ozone depletion in the stratosphere. The operation of boiler, turbine, and generator units (gate hotspots) are the main contributors to climate change impacts, including carbon dioxide (13.30 x 10-2 kg CO2), sulfur dioxide (8.21 x 10-3 kg SO2), and nitrogen dioxide (7.55 x 10-4 kg PO4). Alternative programs that may be implemented to reduce emissions include co-firing and installation of flue gas desulfurization and low NOx burner. The findings of this research provide guidance for developing a policy framework to promote more environmentally friendly coal power plants, thereby achieving greater energy sustainability.

The primary energy source in developing countries, including Indonesia, is fossil energy. Therefore, evaluating the environmental impact of coal-fired steam power plants is crucial, but limited. Comprehensive scientific analysis is required to develop appropriate alternative measures. This research aims to analyze the life cycle impact of the coal power plant at the gate, including the coal yard, coal crusher, boiler, turbine, and generator, with the functional unit of 1 kWh of electricity produced. This research provides clear recommendations for mitigating emissions from the main contributing units. The analysis reveals the highest impact in the climate change potential category (1.40 × 10-1 kg CO2 eq/kWh), while the smallest impact was recorded in the Eutrophication potential category (7.55 × 10-4 kg PO4 eq/kWh), with no impact on ozone depletion in the stratosphere. The operation of boiler and generator units (gate hotspots) are the main contributors to climate change impacts, including carbon dioxide (9.25 × 10-2 kg CO2), sulfur dioxide (8.21 × 10-3 kg SO2), and nitrogen dioxide (7.55 × 10-4 kg PO4). Alternative programs that may be implemented to reduce emissions include co-firing and installation of flue gas desulfurization and low NOx burner. The findings of this research provide guidance for developing a policy framework to promote more environmentally friendly coal power plants, thereby achieving greater energy sustainability. [ABSTRACT FROM AUTHOR]

The increase in greenhouse gas emissions, mainly CO2 is one of the current concerns. Agri-municipal solid waste (MSW) based biomass is a promising eco-friendly alternative source of renewable energy to mitigate the twin problems of fossil fuel depletion and environmental degradation due to CO2 emissions. An integration of mixed fuel-based (coal+biomass) power generation with algal CO2 capture is expected to reduce the CO2 emission. In addition algal biomass, a rich resource of fuel and biochemicals, is produced. This article focuses on the analysis of energy and environmental performance of an integrated system of 30 TPD integrated gasification combined cycle (IGCC) power plant, co-fired with Indian coal and Agri-MSW, and microalgal CO2 capture (70%) unit using three algal strains, namely, Chlorella Vulgaris, Nannochloropsis spp and Scenedesmus spp. The analyses have been performed considering the use of (a) in-house power and (b) grid power for the algal unit individually using Chlorella Vulgaris, Nannochloropsis spp and Scenedesmus using ASPEN Plus modelling. It is expected that the results of the analysis will be helpful in designing an integrated system of coal-biomass based IGCC power plants with algal CO2 capture units using different varieties of biomass and algal strains. [ABSTRACT FROM AUTHOR]

The present study focuses on the numerical modeling of the co-combustion of reject coal (RC) and sal leaves (SL) in a drop tube furnace (DTF) under different conditions, including air-fuel and oxy-fuel environments. The numerical results highlight the significant influence of replacing the N2 atmosphere with CO2 on the temperature profiles of individual fuels and their blends. For instance, when exposed to a 21%O2/79%CO2 atmosphere, Blend SL3 and Blend SL5 experience a decrease in temperature from 1372 K to 1559 K to 1327 K and 1395 K, respectively. Conversely, increasing the O2 concentration to 35% leads to a temperature rise. Furthermore, the combustion analysis reveals that the addition of 10% SL to RC in a 21%O2/79%N2 environment enhances the devolatilization rate from 1.41 × 10−12 kg/s to 1.77 × 10−12 kg/s. Additionally, the char combustion process for all blends is completed closer to the DTF inlet at 0.28 m, compared to 0.32 m for RC alone. These findings indicate that blending SL with RC promotes a favorable combustion process. Moreover, increasing the O2 concentration to 35% in oxy-fuel conditions enhances the temperature profiles. The numerical analysis demonstrates good agreement with experimental data within a range of ±5%–11%. This suggests that the developed model can be effectively utilized for optimizing and designing biomass co-firing systems in industrial applications, considering both air-fuel and oxy-fuel conditions. [ABSTRACT FROM AUTHOR]

Co-firing of biomass with coal combines the environmental benefits of renewable biomass with the high energy content of coal. Although the common numerical simulation treats the biomass and coal particles with ideal morphology, real particles often demonstrate nonsmoothed surface and irregular shape. To understand the impact of particle morphology in a group of biomass and coal particles co-firing together and to inform simple models appropriate, this study investigated the interparticle effects among particles using realistic particle morphology, focusing on fluid dynamics such as temperature distribution, flow patterns and drag coefficients. Particle-scale computational fluid dynamics (CFD) simulations using micro-CT imaging showed that realistic particle shapes resulted in nonuniform flow fields and temperature distributions with different reaction intensities due to the species transportation. It is in contrast to traditional ideal shape models, which often rely on simplified spherical representations of particles and cannot capture the intricacies of real particle shapes. Realistic models revealed more complex surfaces, highly irregular particle structures, and varied reaction zones that affected the overall dynamics. In addition, changing the orientation of one particle affects the combustion characteristics of neighboring particles. This effect is also not captured while using the spherical structure. These differences underscore the critical impact of particle morphology on drag and heat transfer, thereby challenging conventional spherical models. The findings of this study advocate for a paradigm shift in CFD modeling approaches, emphasizing the importance of realistic particle representation to improve the accuracy of predictions and enhance the co-firing system efficiency.

The effort to reduce CO2 and NOx emissions plays a crucial role in mitigating climate change, improving air quality, complying with environmental regulations, and promoting clean technology innovation. Ammonia, as an emission-free fuel, shows significant potential as a co-firing agent with Coal in coal-fired steam power plants (CFSPP). Previous studies have demonstrated promising results in emission reduction through ammonia co-firing. This research presents a numerical analysis based on Computational Fluid Dynamics (CFD) to investigate the co-firing of ammonia with low-calorific Coal (LRC) in the CFSPP Pangkalan Susu Units 3 and 4, with a capacity of 210 MW. The study employs fluid flow modelling and chemical reaction analysis using the Discrete Phase Model (DPM) to provide accurate predictions of temperature distribution and pollutant concentrations in pulverized coal boilers. Cofiring simulations were conducted with ammonia additions of 5 % and 15 % on a calorific basis. Injection experiments from each burner (A-D) were performed to identify the optimal injection location. The simulation results indicate changes in combustion characteristics, particularly in temperature distribution. The main finding reveals a temperature decrease when ammonia is added as a co-firing material, attributed to the higher H2O content, which leads to increased moisture losses. In terms of efficiency, co-firing showed a decline compared to the baseline combustion of 100 % LRC coal due to the more significant moisture losses. The highest reduction in CO2 emissions was observed when 15 % ammonia was injected from burner B in case #6, with a mass fraction value of 0.171 at the boiler outlet. Similarly, the most significant reduction in NOx emissions occurred with a 15 % ammonia co-firing from burner B, yielding a mass fraction value of 8.81E-04 at the boiler outlet. This co-firing technology is expected to enhance decarbonization efforts and optimize the use of renewable energy in the future.

Ni 0.6 Zn 0.4 Fe 2 O 4 (NZF-Zn 0.4) ferrites with different Al–Si–B–Pb (ASBP) glass additions were synthesized via a solid-phase reaction method at 1175 °C. The inclusion of ASBP-glass significantly enhances the grain size, density, shrinkage, and magnetic properties of NZF-Zn 0.4 ferrites without introducing impurity phases. The prepared NZF-Zn 0.4 -1 wt%ASBP ferrites not only exhibit appropriate radial shrinkage but also possess a dense microstructure and outstanding magnetic properties. Subsequently, Y 2.4 Bi 0.5 Al 0.1 Fe 3 O 4 (YIG-Al 0.1) ferrites and NZF-Zn 0.4 -1 wt%ASBP ferrites were chosen as the outer rings and inner cores, respectively. Tightly interconnected YIG-Al 0.1 /NZF-Zn 0.4 –1wt.% ASBP ferrite composite substrates were successfully co-fired within the temperature range of 1175 °C–1225 °C following co-pressing. Furthermore, YIG-Al 0.1 /NZF-Zn 0.4 -1 wt%ASBP composite substrates, co-fired at 1175 °C, exhibit a lack of impurity phases in the interface region, minimal element diffusion, and exceptional electromagnetic properties (NZF-Zn 0.4 -1 wt%ASBP: M s = 81.88 ± 0.05 emu/g; YIG-Al 0.1 : ε r = 18.28 ± 0.05@11.17 GHz, tanδ = 3.14 ± 0.55 × 10−4, M s = 21.62 ± 0.55 emu/g). The wide co-firing temperature range of YIG-Al 0.1 /NZF-Zn 0.4 -1 wt%ASBP composite substrates significantly enhances the shrinkage matching rate of two-phase ferrites, and its exceptional electromagnetic properties hold significant potential for applications in RF band circulators. [ABSTRACT FROM AUTHOR]

A computational fluid dynamics (CFD) model was coupled with an advanced statistical strategy combining the response surface method (RSM) and the propagation of error (PoE) approach to optimize and test the robustness of the co-firing of ammonia (NH3) and coal in a fluidized bed reactor for coal phase-out processes. The CFD model was validated under experimental results collected from a pilot fluidized bed reactor. A 3k full factorial design of nine computer simulations was performed using air staging and NH3 co-firing ratio as input factors. The selected responses were NO, NH3 and CO2 emissions generation. The findings were that the design of experiments (DoE) method allowed for determining the best operating conditions to achieve optimal operation. The optimization process identified the best-operating conditions to reach stable operation while minimizing harmful emissions. Through the implementation of desirability function and robustness, the optimal operating conditions that set the optimized responses for single optimization showed not to always imply the most stable set of values to operate the system. Robust operating conditions showed that maximum performance was attained at high air staging levels (around 40%) and through a balanced NH3 co-firing ratio (around 30%). The results of the combined multi-optimization process performance should provide engineers, researchers and professionals the ability to make smarter decisions in both pilot and industrial environments for emissions reduction for decarbonization in energy production processes. [ABSTRACT FROM AUTHOR]

Co-firing wood pellets with coal is an attractive alternative energy generation method with economic, social, and environmental benefits for the US energy generation sector. One way to sustainably use wood pellets for co-firing is to create consumer-supported green pricing programs (GPPs). Our study surveyed residents of five states (Alabama, New Jersey, New York, Pennsylvania, and Virginia) to investigate preferences for the attributes of a hypothetical GPP. The study applied the Best Worst Choice method, which employs the Best Worst Scaling (BWS) and binary choice (BC) task. The BWS analysis showed that residents of all five states most value the flexibility of contracts, the location of energy generation, and the reduction of carbon emissions as attributes of GPPs. The BC analysis, however, showed that residents are willing to pay a premium for length of contract, followed by reduction of carbon emissions and variability of payments. This study shows that the adoption of optimal GPP attributes can create real customer value. The success of GPPs will depend on increasing enrollment and public support; hence, the next step will be to increase awareness levels and green consciousness through sensitization in the form of public education exercises and media campaigns. Such measures will serve to inform and educate residents on the benefits of GPPs and lessen the gap between intrinsic value and willingness to pay for select attributes. [ABSTRACT FROM AUTHOR]

With increased awareness of the large-scale CO2 emissions from the cement industry, there has been growing focus on greenhouse gas reduction strategies. Among all these strategies, fuel substitution using biomass fuel is extensively used to achieve CO2 zero-emission in cement production. Due to the avoidable high-temperature-generated thermal nitrogen oxides during cement production, research on the impact of biomass application on nitrogen oxide emissions shall be carried out. Three types of biomass fuel and bituminous coal were used to investigate the NO reduction characteristics under different O2 concentrations on experimental benches. It was found that the change in oxygen concentration from 9% to 1% increased the reaction time in the reactor from 555 s to 1425 s, which means the increase in oxygen concentration can lead to shorter reaction time, and correspondingly, the existing time of nitric oxide in the flue gas is also shortened, but the peak value of nitric oxide rises, during the process of O2 concentration changing from 1% to 9%, the peak NO concentration in the flue gas increased from 5.4×10−5 to 1.05×10−4. An increase in O2 concentration greatly reduces the total reduction of NO and the minimum change in NO concentration. The peak NO concentration during the combustion process of corn stalk is 4.56 ×10−4, which is approximately 7 times higher than that of coal, and it is caused by the high amount of N in corn stalk. The addition of raw meal has an inhibitory effect on the reduction of NO: after adding raw meal, the effective reduction time of NO by fuel decreased by about 20%, but adding raw meal raises CO2 concentration of fuel gas in the early stage of reaction. [ABSTRACT FROM AUTHOR]

A Computational Fluid Dynamic study was carried out to match the measured outer ash deposition rates associated with the combustion of petroleum coke (PC)–natural gas in AIR and O2/CO2 (70/30 vol%, OXY70). The fly ash PSD associated with high-fixed-carbon, non-porous fuel was estimated using a shrinking sphere burnout model and employed in conjunction with particle kinetic energy (PKE), particle viscosity (µP), and a critical Weber-number-based capture criterion. Deposition rate predictions were sensitive to the fly ash composition employed for estimating µP due to the significant enrichment of Fe in the deposits. Predictions were insensitive to the specific µP model formulation employed or whether the V2O5 in the ash was assumed to play the role of a glass former or a glass modifier. OXY70 scenario impaction rates were significantly lower than the measured deposition rates when the fly ash PSD associated with the AIR scenario was employed in the calculations. This necessitated an ad hoc modification of the OXY70 fly ash PSD to a coarser range to match the measurements and attributing it to agglomeration resulting from longer residence times and higher temperatures. This shift in PSD was in line with AIR and OXY70 fly ash PSD measurements reported previously. [ABSTRACT FROM AUTHOR]

Ammonia, a reliable low-carbon alternative fuel with energy storage capabilities, has garnered increasing attention for its application of co-firing in coal-fired power plants as a strategy to mitigate direct carbon emissions. However, various types of ammonia production technologies result in diverse economic feasibility and emission intensities. Simultaneously, each stage, spanning from upstream processes such as raw material extraction to downstream applications, contributes to carbon emissions, which cannot be ignored. It is crucial to select the appropriate assessment method to determine the transformation pathways for co-firing systems. To this end, this review presents a comprehensive life cycle assessment of ammonia co-firing systems from a whole industrial chain perspective, encompassing the entire gamut of processes from fuel production and transportation to co-firing. Studies of the industrial chain perspective and of life cycle assessment methodology that are uniquely tailored for co-firing systems are presented. A nuanced exploration of distinct technologies across the spectrum of system processes ensues, including the advantages, limitations, and trends in advancement, based on carbon emissions and economic criteria. Considering the diverse fuel production, especially ammonia, typologies and intricate processes have undergone comprehensive review. The combustion characteristics, emissions, and economic factors associated with the co-firing process are systematically summarized, drawing upon aspects such as dynamics, experiments, simulations, and demonstration projects. This study illuminates the progression and technology selection of co-firing systems across multiple stages of the whole industry chain, thereby furnishing insights relevant to the low-carbon transformation of ammonia co-firing with coal in power plants.

A Computational Fluid Dynamic study was carried out to match the measured outer ash deposition rates associated with the combustion of petroleum coke (PC)–natural gas in AIR and O2/CO2 (70/30 vol%, OXY70). The fly ash PSD associated with high-fixed-carbon, non-porous fuel was estimated using a shrinking sphere burnout model and employed in conjunction with particle kinetic energy (PKE), particle viscosity (µP), and a critical Weber-number-based capture criterion. Deposition rate predictions were sensitive to the fly ash composition employed for estimating µP due to the significant enrichment of Fe in the deposits. Predictions were insensitive to the specific µP model formulation employed or whether the V2O5 in the ash was assumed to play the role of a glass former or a glass modifier. OXY70 scenario impaction rates were significantly lower than the measured deposition rates when the fly ash PSD associated with the AIR scenario was employed in the calculations. This necessitated an ad hoc modification of the OXY70 fly ash PSD to a coarser range to match the measurements and attributing it to agglomeration resulting from longer residence times and higher temperatures. This shift in PSD was in line with AIR and OXY70 fly ash PSD measurements reported previously.

This study was carried out to investigate co-firing of torrefied cocoa pod shells (CPS), coal, and their blends with torrefied CPS/coal of 45%/55%, 30%/70%, and 15%/85%. The pelleted samples were burned in a top-lit updraft (TLUD) stove to assess mass-loss rates, flame temperatures, and flue gas emissions. The results of the study showed that the mass-loss rates and flame temperatures of the blend were closer to the combustion characteristics of the coal along with the smaller percentage of CPS. CO and NOx emissions of the blends increased in proportion to the percentage of torrefied CPS in the blend. The supplement of CPS to coal had a significant effect on a reduction in SO2 emissions. Overall, this study showed that torrefied CPS can be used as a supplemental fuel in coal/biomass co-firing up to 15%. [ABSTRACT FROM AUTHOR]

We investigated the reactivity of P2-type honeycomb layered oxides Na2Ni2TeO6 (NNTO) and Na2Zn2TeO6 (NZTO) co-fired at the temperature from 500 °C to 800 °C. From X-ray diffraction measurements, it was found that the reaction between NNTO and NZTO is unremarkable at the temperature below 700 °C. However, when annealed at 800 °C, they formed the solid-solution phase without any secondary phases. The NNTO and NZTO composite pellets co-fired at 800 °C showed sodium-ion conductivity well above 10−4 S cm−1 at room temperature, indicating that the solid-solution phase of NNTO and NZTO has good ionic conductivity. A maximum room temperature conductivity of 7.4 × 10−4 S cm−1 was confirmed at the mixing ratio NNTO: NZTO = 0.5 : 1.5. These results can be applied to the fabrication of all-solid-state batteries using NNTO as the cathode active material and NZTO as the solid electrolyte via a simple co-sintering process.

In order to improve the combustion performance of anthracite coal and solve the problem of resource utilization of distillers’ grains, experiments on the mixing combustion of anthracite coal and distillers’ grains were carried out and the effects of different combustion conditions on their ash characteristics were investigated in order to provide theoretical guidance for the optimization of combustion parameters in the actual operation of power plants. The ash samples were made on a drop tube furnace and a tube furnace, and then the microscopic morphology of the slag was observed by Scanning Electron Microscope-Energy Dispersive Spectrometer (SEM-EDS), while its mineralogical composition was analysed by X-ray diffraction (XRD). The results show that the increase of distillers’ grain mixing ratio, combustion temperature and oxygen concentration will lead to the deterioration of ash slagging characteristics, while the excess air coefficient has little effect on it.

Combining biomass fuel with coal in circulating fluidized bed (CFB) boilers is attractive as the increasing of energy demand. The characteristics of biomass/coal co-firing in the industrial boiler are then investigated using computational fluid dynamics (CFD). In this study, fuels of interest are coal, wood chips, and bark. The fuel proportions were set for investigating their effects on the combustion using a simplex centroid mixture design. CFD simulations consist of a standard k-epsilon viscosity flow model, Euler multiphase fluid flow model, and a simplified biomass-char combustion reaction model. The predictive responses of the model are bed temperature, heat flux, and carbon dioxide (CO2) and carbon monoxide (CO) mass flows. The simulation results showed that the operation with coal gave the highest temperature and heat flux, followed by wood chips and bark. On the other hand, the operation with biomass releases fewer gas emissions, CO2 and CO, than those of the operation with coal. The type and proportion of boiler fuel can be easily determined using two methods: predictive equation and ternary contour plot graph, which can be likened to the digital twin of biomass/coal co-firing boiler.

Co-firing is the activity of adding biomass to the combustion process as a mixed fuel for coal in power plants. In 2021 co-firing has been carried out at 17 PLTUs in Indonesia. The co-firing program at a steam power plant is a form of reducing coal consumption which can reduce carbon emissions while increasing the use of renewable energy without increasing investment in new power plants. PLTU X in West Java, Indonesia has implemented co-firing using sawdust biomass using the direct method without adding or modifying equipment. The use of biomass is obtained from wood-cutting waste, with a ratio of sawdust biomass usage

Coal-fired power generation resulted in a shortage of conventional fossil fuels and an increase in greenhouse gas emissions. The co-firing of coal and biomass waste in coal-fired boilers was a promising strategy to supplement the energy source and reduce greenhouse gases. However, the co-firing mechanism and potential problems were not well understood. Therefore, the differences between coal and biomass in properties such as proximate and ultimate composition, components in ash and the calorific value were first discussed. Next, compared with the combustion of coal alone, this review analyzed the discrepancies and corresponding issues of co-firing in combustion behaviors and products such as ash and gaseous pollutants. Finally, this review outlined how operational conditions could affect the co-firing performance.

Biomass syngas can be considered as a supplementary fuel to partially substitute coal, which is beneficial to CO2 emission reduction. For the case study, the influences of co-firing typical biomass syngas (gasification from palm, straw, and wood) with coal on the thermodynamic parameters of a 300 MW tangentially fired boiler are evaluated through a thermal calculation based on the principles of mass conservation, heat conservation, and heat transfer. The effects of boiler loads, biomass syngas species, and consumption rates are discussed. The results show that the introduction of biomass syngas weakens the radiative characteristics of the flame and reduces the furnace exit flue-gas temperature. As 3 × 104 m3 h−1 of wood syngas is introduced, the decrement of thermal efficiency reaches 0.4%, while that of the coal consumption rate is 5.1%. The retrofitting of the boiler was not necessary and the corrosion of the low-temperature heating surface did not appear. The CO2 annual emission reduction could achieve 0.001 to 0.095 million tons for palm syngas, 0.005 to 0.069 million tons for straw syngas, and 0.013 to 0.107 million tons for wood syngas with increasing biomass syngas consumption rates under the full load. Moreover, the main thermodynamic parameters changed more significantly under the low loads. [ABSTRACT FROM AUTHOR]

Integrating hydrogen firing and a carbon capture plant (CCP) into a natural gas combined cycle (NGCC) power plant is a promising strategy for reducing CO2. In this study, process simulation in Aspen PLUS of hydrogen co-firing in a 40 MW turbine gas combined cycle power plant was done at an identical gas turbine inlet temperature from 0%.cal to 30%.cal. The evaluated cases were hydrogen co-firing with CCP (H2 Co-firing + CCP) and hydrogen co-firing without CCP (H2 Co-firing). The results showed a 6% CO2 emission reduction per 5% increase in hydrogen, albeit with increased NOx emissions. H2 Co-firing experienced a decrease in net power with rising hydrogen co-firing, while H2 Co-firing + CCP saw an increase but remained below Case 2 due to the energy penalty from the carbon capture plant. The capital cost of H2 Co-firing + CCP exceeds that of H2 Co-firing due to CCP usage, impacting gross revenue. The sensitivity analysis indicated that the cost of hydrogen has higher sensitivity compared to the cost of CCP. Lowering hydrogen prices is recommended to effectively reduce CO2 emissions in NGCC. [ABSTRACT FROM AUTHOR]

Rice husk (RH) co-combustion with natural gas in highly oxygen-enriched concentrations presents a net carbon-negative energy production opportunity while minimizing flue gas recycling. However, recent experiments have shown enhanced ash deposition rates in oxygen-enriched conditions, with deposition/shedding also being dependent on the particle size distribution (PSD) of the parent RH fuel. To uncover the causative mechanisms behind these observations, add-on models for ash deposition/shedding and radiative properties were employed in computational fluid dynamics simulations. The combustion scenarios investigated encompassed two types of RH (US RH, Chinese RH) with widely varying ash contents (by % mass) and inlet fuel PSD with air and O2/CO2 (70/30 vol %, OXY70) as oxidizers. Utilizing the measured fly-ash PSDs near the deposit surface and modeling the particle viscosity accurately, particle kinetic-energy (PKE)-based capture and shedding criteria were identified as the keys to accurate deposition/shedding rate predictions. The OXY70 scenarios showed higher ash-capturing propensities due to their lower PKE. Conversely, higher erosion rates were predicted in the AIR firing scenarios. In addition, the radiative characteristics across all the scenarios were dominated by the gases and were not sensitive to the fly-ash PSD. Therefore, the higher particle concentrations in the OXY70 conditions did not negatively impact the heat extraction.

Abstract Co‐firing residual lignocellulosic biomass with fossil fuels is often used to reduce greenhouse gas (GHG) emissions, especially in processes like cement production where fuel costs are critical and residual biomass can be obtained at a low cost. Since plants remove CO2 from the atmosphere, CO2 emissions from biomass combustion are often assumed to have zero global warming potential (GWPbCO2= 0) and do not contribute to climate forcing. However, diverting residual biomass to energy use has recently been shown to increase the atmospheric CO2 load when compared to business‐as‐usual (BAU) practices, resulting in GWPbCO2 values between 0 and 1. A detailed process model for a natural gas‐fired cement plant producing 4200 megagrams of clinker per day was used to calculate the material and energy flows, as well as the lifecycle emissions associated with cement production without and with diverted biomass (supplying 50% of precalciner energy demand) from forestry and landfill sources. Biomass co‐firing reduced natural gas demand in the precalciner of the cement plant by 39% relative to the reference scenario (100% natural gas), but the total demands for thermal, electrical, and diesel (transportation) energy increased by at least 14%. Assuming GWPbCO2 values of zero for biomass combustion, cement's lifecycle GHG intensity changed from the reference (natural gas only) plant by −40, −23, and − 89 kg CO2/Mg clinker for diverted biomass from slash burning, forest floor and landfill biomass, respectively. However, using the calculated GWPbCO2 values for diverted biomass from these same fuel sources, the lifecycle GHG intensities changes were −37, +20 and +28 kg CO2/Mg clinker, respectively. The switch from decreasing to increasing cement plant GHG emissions (i.e., forest floor or landfill feedstocks scenarios) highlights the importance of calculating and using the GWPbCO2 factor when quantifying lifecycle GHG impacts associated with diverting residual biomass to bioenergy use.

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 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.

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.

It is known that simple adding of wood allows one to accelerate the ignition of powder mixtures compared to the situation when pure coal is used. This study focuses on testing the hypothesis about the effect of co-milling coal and wood on their co-firing: is the case of composite powdered fuels should ensure the maximum possible efficiency of heat and mass transfer? Firstly, we will show that co-milling of coal and wood leads not independent size reduction of two materials but gives composite powder – coal-covered wood. For the composite fuel further reduction of the ignition delay time of air suspension and reduction of the limit volume concentration required for flame propagation have demonstrated. Obtained synergy also manifests in thermogravimetry. Here we propose a simple method for analyzing the mass loss curves. For any coal-to-wood sawdust ratio, combustion of the composites and mixtures both can be viewed as a weighted sum of the curves of individual components. But only in the case of composites calculated sawdust content is higher than the actual one: the mass loss is redistributed towards the stage occurring at lower temperatures due to geometry of wood/coal contact.

A computational fluid dynamics (CFD) model was coupled with an advanced statistical strategy combining the response surface method (RSM) and the propagation of error (PoE) approach to optimize and test the robustness of the co-firing of ammonia (NH3) and coal in a fluidized bed reactor for coal phase-out processes. The CFD model was validated under experimental results collected from a pilot fluidized bed reactor. A 3k full factorial design of nine computer simulations was performed using air staging and NH3 co-firing ratio as input factors. The selected responses were NO, NH3 and CO2 emissions generation. The findings were that the design of experiments (DoE) method allowed for determining the best operating conditions to achieve optimal operation. The optimization process identified the best-operating conditions to reach stable operation while minimizing harmful emissions. Through the implementation of desirability function and robustness, the optimal operating conditions that set the optimized responses for single optimization showed not to always imply the most stable set of values to operate the system. Robust operating conditions showed that maximum performance was attained at high air staging levels (around 40%) and through a balanced NH3 co-firing ratio (around 30%). The results of the combined multi-optimization process performance should provide engineers, researchers and professionals the ability to make smarter decisions in both pilot and industrial environments for emissions reduction for decarbonization in energy production processes.

Co-firing wood pellets with coal is an attractive alternative energy generation method with economic, social, and environmental benefits for the US energy generation sector. One way to sustainably use wood pellets for co-firing is to create consumer-supported green pricing programs (GPPs). Our study surveyed residents of five states (Alabama, New Jersey, New York, Pennsylvania, and Virginia) to investigate preferences for the attributes of a hypothetical GPP. The study applied the Best Worst Choice method, which employs the Best Worst Scaling (BWS) and binary choice (BC) task. The BWS analysis showed that residents of all five states most value the flexibility of contracts, the location of energy generation, and the reduction of carbon emissions as attributes of GPPs. The BC analysis, however, showed that residents are willing to pay a premium for length of contract, followed by reduction of carbon emissions and variability of payments. This study shows that the adoption of optimal GPP attributes can create real customer value. The success of GPPs will depend on increasing enrollment and public support; hence, the next step will be to increase awareness levels and green consciousness through sensitization in the form of public education exercises and media campaigns. Such measures will serve to inform and educate residents on the benefits of GPPs and lessen the gap between intrinsic value and willingness to pay for select attributes.

This paper focuses on a CCHP (Combined Cooling, Heating and Power) system based on co-firing in an Internal Combustion Engine (ICE) of biogas from anaerobic digestion and syngas produced by biomass gasification. From an energy perspective, in order for the mixture to make sense, a relationship setting the threshold percentage of methane in the biogas has been established. Gasification and Organic Rankine Cycle (ORC) models developed in Aspen Plus software and thermodynamic modeling of the Internal Combustion Engine (ICE) have been validated by comparison with experimental work conducted by other authors. The results show a decrease in energy efficiency with an increase in the percentage of methane in biogas and the mass ratio of the mixture. For extraction rates of 80 % and 90 %, respectively, exergy efficiency increases with an increase in the percentage of methane in biogas and the mass ratio of the mixture. Additionally, an increase in gasification temperature improves the efficiencies, while an increase in biogas temperature reduces them. The ICE is a significant source of exergy destruction.

Torrefied wood originating from beetle-killed trees is an abundant biomass fuel that can be co-fired with coal for power generation. In this work, pulverized torrefied wood, a bituminous coal (Sufco coal) and their blended fuel with a mixing ratio of 50/50 wt.%, are burned in a 100-kW rated laboratory combustor under similar conditions. Ash aerosols in the flue gas and ash deposits on a temperature-controlled surface are sampled during combustion of the three fuels. Results show that ash formation and deposition for wood combustion are notably different from those for coal combustion, revealing different mechanisms. Compared to the coal, the low-ash torrefied wood produces low concentrations of fly ash in the flue gas but significantly increased yields (per input ash) of ash that has been vaporized. All the mineral elements including the semi- or non-volatile metals in the wood are found to be more readily partitioned into the PM 10 ash than those in the coal. The inside layer deposits sticking to the surface and the loosely bound outside deposits exposed to the gas both show a linear growth in weight during torrefied wood test. Unlike coal combustion, in which the concentration of (vaporized) ash PM 1 controls the inside deposition rate, wood combustion shows that the formation of porous bulky deposits by the condensed residual ash dominates the inside deposition process. Co-firing removes these differences between the wood and coal, making the blended fuel to have more similar fly ash characteristics and ash deposition behavior to those of the bituminous coal. In addition, results also show some beneficial effects of co-firing coal with torrefied wood, including reduction of the total deposition rate and the minimization of corrosive alkali species produced by wood. [ABSTRACT FROM AUTHOR]

Highly resolved Large Eddy Simulations (LES) are performed to investigate co-firing of coal and ammonia in a burner experiment conducted by the Central Research Institute of Electric Power Industry (CRIEPI) in Japan. The coaxial burner with a hydrogen supported pulverized coal flame is modeled using the in-house code PsiPhi. A three mixture fraction flamelet/progress variable (FPV) approach is employed to simulate coal particle conversion due to devolatilization, hydrogen combustion, and ammonia combustion. Three cases are investigated and compared to each other: 1) a coal combustion case, injecting air and coal particles, 2) an ammonia combustion case, injecting a mixture of ammonia and air, and 3) a co-firing combustion case, injecting a mixture of coal, ammonia and air in the center tube. Two mechanisms are used to build the chemistry table and are compared against each other: a reduced CRECK mechanism with 120 reaction species and 1551 elementary reactions, originally reduced for coal combustion modeling, and a newly introduced reduced CRECK mechanism with 129 reaction species and 1644 elementary reactions, including the detailed NH 3 reaction paths in addition to the coal chemistry. Species are compared for the coal case and temperature fields are compared for both the coal and co-firing case. Normalized LIF signals for OH and NH are presented for all three cases. The gas composition profiles are in good agreement with the experiment and the temperature fields are consistent with previous results for the pure coal flames. For pure ammonia and for ammonia co-firing, the new mechanism shows an improved prediction of the reaction zone. [ABSTRACT FROM AUTHOR]

Rice husk (RH) co-combustion with natural gas in highly oxygen-enriched concentrations presents a net carbon-negative energy production opportunity while minimizing flue gas recycling. However, recent experiments have shown enhanced ash deposition rates in oxygen-enriched conditions, with deposition/shedding also being dependent on the particle size distribution (PSD) of the parent RH fuel. To uncover the causative mechanisms behind these observations, add-on models for ash deposition/shedding and radiative properties were employed in computational fluid dynamics simulations. The combustion scenarios investigated encompassed two types of RH (US RH, Chinese RH) with widely varying ash contents (by % mass) and inlet fuel PSD with air and O2/CO2 (70/30 vol %, OXY70) as oxidizers. Utilizing the measured fly-ash PSDs near the deposit surface and modeling the particle viscosity accurately, particle kinetic-energy (PKE)-based capture and shedding criteria were identified as the keys to accurate deposition/shedding rate predictions. The OXY70 scenarios showed higher ash-capturing propensities due to their lower PKE. Conversely, higher erosion rates were predicted in the AIR firing scenarios. In addition, the radiative characteristics across all the scenarios were dominated by the gases and were not sensitive to the fly-ash PSD. Therefore, the higher particle concentrations in the OXY70 conditions did not negatively impact the heat extraction. [ABSTRACT FROM AUTHOR]