Trimethylolethane trinitrate (TMETN) is a promising insensitive nitrate ester plasticizer for replacing highly sensitive nitroglycerin (NG), but its high-temperature ignition behavior, pyrolysis chemistry, and detailed condensed-phase decomposition mechanism remain insufficiently understood. In this work, the ignition, pyrolysis, and thermal decomposition mechanism of TMETN were systematically investigated by combining high-pressure shock tube experiments, ReaxFF reactive molecular dynamics (ReaxFF MD) simulations, and high-level quantum chemical calculations. Ignition delay times (IDTs) were measured at 5, 10, and 20 bar in Ar and Ar/O2 atmospheres, and 14 major gaseous pyrolysis products were identified under high-temperature and high-pressure conditions. ReaxFF MD simulations were performed to analyze the temporal evolution of key intermediates and final products, while quantum chemical calculations were carried out to clarify the thermodynamic and kinetic preference between NO2 and HONO elimination pathways. The results show that: (1) TMETN ignition exhibits a strong pressure dependence. In Ar, the measured IDTs decrease from 0.78–0.876 ms at 5 bar to 0.52–0.609 ms at 10 bar and 0.23–0.301 ms at 20 bar; in Ar/O2, the IDTs decrease from 0.734–0.832 ms at 5 bar to 0.493–0.580 ms at 10 bar and 0.208–0.273 ms at 20 bar. (2) As the temperature increases, the concentrations of hydrocarbon products increase, whereas those of oxygen-containing intermediates such as methanol and formaldehyde decrease, indicating that higher temperatures promote the deep cracking and secondary decomposition of TMETN. (3) ReaxFF MD simulations capture the temperature-dependent evolution trends of representative products and reveal that O–NO2 bond cleavage accompanied by NO2 release dominates the initial decomposition stage of TMETN. (4) Quantum chemical calculations further demonstrate that NO2 elimination is generally more favorable than the competing HONO elimination pathway in terms of reaction barriers, reaction enthalpies, and temperature-dependent rate constants. These results indicate that the thermal decomposition of TMETN is mainly initiated by nitrate ester bond cleavage, followed by NOx/HONO-related secondary reactions and the formation of stable small-molecule products such as N2, CO2, and H2O. This work provides quantitative ignition data and a cross-scale mechanistic interpretation of TMETN thermal decomposition, offering a theoretical basis for kinetic model development and the safe application of insensitive energetic plasticizers.

After desulfurization, the trace amounts of SO2 contained in real coal-fired flue gas tend to induce the deterioration of potassium-based adsorbent for CO2 capture and shorten the service life. In this study, Al2O3 aerogel was synthesized via a sol-gel approach using crystalline aluminum chloride as the precursor material, while CeKAl adsorbents were fabricated using an impregnation technique. Employing a fixed-bed adsorption reaction test setup, the performance of CO2 capture and sulfur resistance of adsorbents were studied. The impact of reaction conditions on adsorbent uptake behavior was analyzed using the Avrami adsorption kinetic model, and the microstructure of the adsorbent was analyzed by various characterization methods. The results showed that during adsorption experiments in an atmosphere containing 150 mg/m3 SO2, CeO2 reacts with SO2 to form Ce2(SO4)3, and the CO2 adsorption capacity increased by 32.61%. The optimal doping amount of CeO2 is 2%, and the optimal adsorption conditions are 15% CO2 concentration, 60 degrees C reaction temperature, and 15% H2O concentration. After ten adsorption-desorption cycles, the adsorption property of the adsorbent is stable at about 1.64 mmol/g. Based on DFT analysis, the mechanism of CO2 adsorption and sulfur resistance of CeKAl adsorbents were investigated from the atomic level. The p orbitals of the S and O atoms in SO2 resonate with the f orbitals of Ce atoms, and the adsorbent exhibits sulfur resistance. In the presence of SO2, the energy barrier for carbonation of CO2 and H2O on the CeKAl(0001) surface is reduced to 137.52 kJ/mol, confirming the sulfur resistance effect of the doped adsorbent.

An electrical heating fluidized-bed thermal energy storage (EH-FB-TES) system is proposed for integration with a coal-fired power plant (CFPP) for deep peak shaving (DPS) due to its high energy storage density and extensive heat exchange performance. The primary objective of this study is to evaluate the thermodynamic performance and economic feasibility of the integrated EH-FB-TES system, specifically focusing on identifying the optimal coupling and heat recovery strategies for enhanced deep peak shaving performance. Since EH-FB-TES uses air flow for fluidization in the heating storage process, its coupling with the CFPP differs from other TES technologies, and the associated thermodynamic performance and cost are thereby analyzed. The results show that, in EH-FB-TES, the heat release efficiency is predominantly constrained by thermal losses. To increase the energy utilization efficiency, a two-stage heat recovery strategy is proposed to release the stored energy in the integration. The first stage is to heat up the feedwater extracted from the deaerator and the second one is to heat up the condensate water. The analyses also show that the selection of reinjection positions for the heated medium from EH-FB-TES greatly influences the system performance. Returning the stored thermal energy to heat up feedwater can effectively increase the output of the unit, while directly generating steam can be beneficial for coal saving. The integrated system achieves a maximum equivalent round-trip efficiency of 32.9% under 20 MW/800 degrees C conditions. An economic analysis reveals that, compared with other energy storage methods, EH-FB-TES can realize a relatively high energy storage density with a rather low cost. Under the present DPS compensation policy, for a 315 MW subcritical CFPP integrated with a 50 MW EH-FB-TES system, when heat storage is 8 h, heat release is 4 h per day, and the plant operates 100 days per year, the estimated static and dynamic payback periods are 3.06 years and 3.67 years, respectively. The integration of CFPP with EH-FB-TES could be promising for meeting DSP requirements.

Impinging wind jets commonly occur in tunnels and passages, whose non-uniform flow can significantly alter flame behavior.This paper investigates flame spread over double wires under varying side-confined distances (D = 0~15 mm), wire spacings (S = 0~16 mm), and nozzle exit velocities (Uf = 0~0.4 m/s) generated by an impinging jet system. Results show that flame morphology is governed by flow regions, with forward flow zone exhibiting larger flames and distinct "flame displacement". Pm decreases with increasing D and S, and is significantly changed by Uf. The stagnation zone shows higher merging probability due to cross-flow dominance. Flame tilt angle is determined by wind drag force (Fw), buoyancy force (Ff), and interaction force (Fi). In the reverse and forward flow zones, the longitudinal tilt angle θ is determined by the competition between buoyancy and wind drag, following the relationship . Meanwhile, the transverse tilt angle α in these zones arises for the combined effects of flame interaction and buoyancy, expressed as. In the stagnation zone, Fr number effectively has the relationship with transverse tilt angle and Pm, following as . FSR can be sorted as: forward flow > reverse flow > stagnation zone, due to the inner/outer wire velocity difference governed by wall jet wind speed u. A heat transfer model based on heat feedback components is established to well predict the flame spread rate within ±15% errors.

In the ironmaking process, replacing coke with hydrogen-enriched gas is an effective approach to reducing carbon emissions and enhancing the energy efficiency of the blast furnace. In the meantime, using the exhaust gas from the blast furnace and coke oven for heating and power generation through gas-fired boilers can further promote energy conservation and emission reduction. Under this circumstance, the present study focused on the effect of variation in fuel components on the environmental and efficiency of gas-fired boilers based on the hydrogen-rich ironmaking process. The variation of blast furnace gas (BFG) components discharged from the blast furnace with the injection of hydrogen-enriched gas, i.e., the mixture of coke oven gas (COG) and green hydrogen, was first discussed. Then, taking a 110 t/h BFG-fired boiler as an example, when respectively using BFG and BFG-COG-H-2 (the mixture of BFG, COG, and H-2) as fuel to maintain a constant boiler evaporation rate and excess air ratio, the comprehensive boiler performances in terms of thermodynamic characteristics, decarbonization potential, and NOx emissions were investigated by the combined thermodynamic, heat transfer, and chemical reaction network models. The results show that as the H-2 content increases by similar to 65 % and the CO content decreases by similar to 23 % in BFG, the decarbonization potential improves by 19.1 %, the boiler thermal efficiency increases by 1.4 % from 90.93 % to 92.18 %, and NOx emissions also rise by 7.9 % from 23.02 mg/m(3) to 24.83 mg/m(3). After blending BFG with COG-H-2, the decarbonization potential of the boiler will be further improved by over 30 %. As the H-2 content increases by similar to 66 % and the CO content decreases by similar to 28 % in BFG-COG-H-2, the decarbonization potential improves by 11.8 %, the boiler thermal efficiency decreases by 0.2 % from 93.57 % to 93.40 %, and NOx emissions also decline by 9.7 % from 40.75 mg/m(3) to 36.78 mg/m(3). There exists a trade-off between increasing boiler thermal efficiency and decreasing NOx emissions.

The effects of incoming flow mixing uniformity and co-flow on the flashback of laminar syngas/air jet flames for a micro-mixing burner were experimentally and numerically studied. The results showed that at the onset of flashback, induced by diffusional-thermal instability, flames possessed a pyramid structure and with rotation at a relatively small equivalent ratio. The mixing uniformity did not affect the flashback mechanism. At a small phi, the flashback velocity (UFB) at different mixing modes were nearly the same. While at a high phi, UFB was larger at a poorer fuel/air mixing. With a hot co-flow, UFB increased and more rapidly changed with phi. Moreover, the lean limit decreased and flashback propensity increased. Besides, UFB was less sensitive to mixing uniformity with hot co-flow. In this case, the incoming flow mixing effect was obvious but less important than the change of SG caused by high temperature mixing of co-flow.

In response to the global mandate for carbon emission reduction, ammonia (NH3) has garnered attention as a viable carbon-free fuel alternative to coal for power generation due to its cost-effectiveness, safety, and ease of storage and transport. Circulating fluidized bed (CFB) boilers are well suited for ammonia-coal co-firing, as their moderate combustion temperatures suppress NOx formation. However, this thermal environment introduces technical challenges, such as incomplete ammonia oxidation and elevated NH3 slip. This study utilized Computational Particle Fluid Dynamics (CPFD) simulations to systematically investigate the effects of NH3 injection elevation, jet configuration patterns, and water-cooled wall area under high-ratio ammonia-coal co-firing conditions in CFB boilers. Results show that co-firing ammonia with coal reduces NO but increases N2O emissions. Optimal NH3 combustion was achieved when injection occurred near the transition zone. A configuration of 16 opposed nozzles combined with 4 tangential corner jet improves NH3 conversion and reduces NO and N2O emissions by 11-13 % compared to using 4 opposed nozzles. Reducing the water-cooled wall area increases bed temperature by 20 to 40 degrees C, enhancing NH3 conversion by 1.55 % and lowering N2O emissions by 10.34 %, but raises NO emissions by 30.46 %. These findings provide crucial guidance for optimizing ammonia-coal co-firing in CFB boilers, highlighting the trade-offs between combustion efficiency enhancement and pollutant emission control.

Although the number of coal mine fire accidents, casualties per incident, and economic losses have shown a downward trend in recent years, the planning of evacuation routes for mine workers remains a critical task in mining disaster management. Therefore, this study proposes a method combining genetic algorithms with tabu search. The tabu search's excellent local exploration capability prevents the genetic algorithm from premature convergence, while introducing adaptive mutation probabilities helps the genetic algorithm escape local optima. Comparisons with other algorithms demonstrate the feasibility of the proposed method, which aids in designing and planning escape routes for personnel.

This study investigated the catalytic and non-catalytic transformation of methane over Fe2O3/Al2O3 oxygen carriers under oxygen-carrier-aided combustion (OCAC)-relevant conditions. A novel thermogravimetric tubular-flow fixed-bed reactor (TG-TFBR) is developed to simultaneously monitor solid weight changes and exhaust gas composition, enabling determination of intrinsic reaction kinetics with minimized external mass transfer limitations. The intrinsic kinetic parameters are determined by coupling a 0-D single-particle random pore model with a 1-D packed-bed reactor model, and the Arrhenius relationship is used to correlate rate constants with temperature. Redox experiments reveal distinct two-stage reduction behavior of Fe2O3 at 800–900 °C, with almost complete conversion to Fe3O4 in Stage 1 and complete reduction to FeO only at 900 °C by the end of Stage 2. At 700 and 750 °C, only a single stage is observed and leads to partial reduction to Fe3O4, indicating a hindered Fe3+ → Fe2+ reduction and weakened oxygen-release capacity at lower temperatures. Catalytic oxidation experiments demonstrated that increasing temperature and oxygen concentration significantly enhanced CH4 conversion and CO2 yield. Compared with homogeneous reactions, Fe2O3/Al2O3 oxygen carriers exhibit clear catalytic promotion, with exhibiting a lower activation energy and higher rate constant. Overall, the findings elucidate the dual catalytic and oxygen-carrier roles of Fe2O3 in methane transformation under OCAC-relevant conditions. It supports more accurate modeling of OCAC processes and helps guide operating strategies to enhance fuel utilization.

Al-doped lithium lanthanum zirconate (Li7La3Zr2O12, LLZO) is a promising solid electrolyte material for all-solid-state lithium batteries due to its high ionic conductivity and thermal stability. Flame-based synthesis is an effective method for synthesizing nanoscale LLZO particles. In the present study, we propose a combined spray-drying and flame-based synthesis (SD-FS) process for producing cubic-phase LLZO, using a rotating-plane premixed stagnation flame (RPSF) apparatus with cost-effective feedstocks (including nitrate salt, water, and ethanol), followed by sintering processes to obtain a high-performance LLZO solid electrolyte. The combined SD-FS mechanism and the effect of sintering methods on the ionic conductivity of final LLZO solid electrolytes are investigated. Experiments and mathematical models reveal that the fed droplets undergo the stages of solvent evaporation, spherical shell precipitation, precursor melting and evaporation, nucleation, and collision, ultimately forming nanoparticles. The nano-sized morphology and the hot-pressing sintering, which involves a high pressure (40 MPa) with heating (1473 K for 2 h), are proven beneficial to the ionic conductivity of the sintered electrolyte pellets. Al-doped LLZO SSE pellets with an ionic conductivity of 4.7 & times; 10-4 S & centerdot;cm-1 are synthesized using ethanol-blended nitrate aqueous solution as the precursor and employing the hot-pressing method as the sintering process.

Ammonia, recognized as a carbon-free and hydrogen-rich fuel, is receiving growing attention as part of global carbon-reduction strategies. Co-firing ammonia in coal-fired equipment offers a practical pathway to lower CO2 emissions from existing units. This study quantifies how ammonia blending ratio, oxygen mole fraction, and swirl number affect the ignition of ammonia-coal co-firing flames using a Hencken burner. Unlike most prior studies, we employed a high pulverized coal loading of 0.75 kg & sdot;m3 in the primary air, representative of boiler conditions and examined three particle size fractions with dominant sizes of 48---75 mu m, 75---96 mu m, and 96---120 mu m. Visible light image and its RGB channel resolved four characteristic regions of the flame: preheating, gaseous ignition/combustion, primary combustion, and burnout zones. Experimental results demonstrated that ammonia significantly influenced coal ignition characteristics by altering flame morphology and ignition delay times. Under non-swirling conditions (S = 0), increasing the ammonia blending ratio from 0 % to 30 % produced a clear increase in ignition delay time, attributed primarily to preferential O2 consumption by NH3 oxidation. Raising the swirl number from 0 to 0.78 substantially shortened the ignition delay by approximately 75---78 % due to enhanced turbulent mixing and the formation of a central recirculation zone. Increasing the oxygen mole fraction in the hot flue gas from 13.8 % to 31.7 % further reduced the delay by about 20 %. A stronger swirling field also promoted interactions between NH3 oxidation intermediates and coal volatiles, which improved flame stability and combustion efficiency. This study provides insights into the coupling effects of swirl and ammonia blending, thereby offering practical guidance for the industrial-scale implementation of ammonia-coal co-firing technologies aimed at achieving efficient combustion and substantial carbon emission reductions.

To enhance the capability of deep participation in electricity load regulation and absorb curtailed renewable energy, a regulation strategy for coal-fired power units integrated with multi-time-scale energy storage is proposed, addressing the high costs of single energy storage solutions. A 660 MW Circulating Fluidized Bed (CFB) power plant integrated with Solid Oxide Electrolysis Cells (SOEC) for hydrogen storage, Thermal Energy Storage (TES), and Battery Energy Storage Systems (BESS) forms the core unit for grid stability and load balancing. The system is modeled in Aspen Plus, with thermodynamic and economic models developed to evaluate performance, storage capacity, response time, efficiency, and economic feasibility. Results show that BESS is optimal for shortterm, high-efficiency operations, SOEC excels in long-duration storage with a Levelized Cost of Electricity (LCOE) of 3.09 CNY/kWh, and TES offers a cost-effective medium-term solution with an LCOE of 0.72 CNY/kWh, considering renewable energy pricing. As storage duration extends to two weeks, annual energy losses increase to 3.00% for TES and 5.45% for BESS, raising their LCOE above that of SOEC, whose storage loss remains relatively stable under continuous hydrogen export. By leveraging each technology's strengths, the strategy decomposes net grid load into time-scale components, aligning them with responsive storage to ensure dynamic grid balancing and enhance renewable integration. A case study of the Shanxi power grid shows the coordinated strategy achieves short payback through efficient multi-scale energy recovery, especially when curtailed renewable energy pricing is negligible, despite SOEC's higher initial costs. The hydrogen-oriented mode currently offers superior economics, while both electricity- and hydrogen-oriented modes are expected to be viable for coal units, including both CFB and conventional coal-fired plants, as SOEC technology matures, confirming the strategy's competitiveness and practical potential for multi-time-scale energy storage regulation.

Designing efficient, stable dual-functional combustion catalysts remains a key challenge in developing next-generation solid propellants, particularly in achieving wide pressure plateau combustion. Herein, we synthesize a series of carbon dot-based catalysts (CDs-1, CDs-2, CDs/Cu) via oxidative etching and hydrothermal methods, and employ them to replace conventional carbon black (CB) at 0.65 wt% loading in the preparation of HMX-CMDB propellants. Systematic evaluation through combined thermochemical analysis (50–350 °C), laser ignition diagnostics (50–350 W/cm2), and combustion chamber testing (4–18 MPa) reveals remarkable catalytic enhancements. The optimized CDs/Cu catalyst demonstrates multifunctional superiority: (1) 7.4 °C reduction in HMX-CMDB decomposition temperature at 10 °C/min (from 205.2 °C to 196.0 °C); (2) 66.7% decrease in laser ignition delay (from 45 ms to 15 ms); (3) 190.9% burning rate increase at 4 MPa (from 4.61 mm/s to 13.41 mm/s); (4) lower pressure exponent of 0.02 within 4–18 MPa range. Notably, CDs-1 induces stable "Plateau" combustion (4–14 MPa), while CDs/Cu achieves "Mesa" effects (8–12 MPa) via synergistic thermal feedback mechanisms-both phenomena ensure stable operation of the engine. Mechanistic studies integrate thermochemical kinetics, ignition combustion process, combustion flame structure, and combustion wave temperature distribution trends, which establish a new paradigm for the study of high efficiency combustion catalysts for solid propellants.

IntroductionDimethyl ether (DME) has potential to be used both blended with or as an alternative to Liquefied Petroleum Gas (LPG) to reduce the carbon emissions of a fuel used globally for cooking and heating. Standards to enable the adoption of this require flame speed measurements of the blends of these fuels.MethodsMeasurements of counterflow premixed flame speeds for blends of DME, propane, butane, and propylene at fuel-air equivalence ratios (φ) from 0.75 to 1.6 have been made. These measurements were taken to fill a gap in the current published datasets that primarily have focussed on pure fuels and blends of LPGs constituent gases. These measurements have been produced through a mixture of empirical and simulation work.ResultsWe found the flame speeds of the blends overall increase from 0.25 m/s at φ = 0.75 to between 0.4 m/s and 0.45 m/s at φ = 1.0 peaking around φ = 1.0 to 1.1 before decreasing as φ increases further.DiscussionThese data will be useful to support the production of industrial standards that allow for greater adoption of renewable DME as an alternative low carbon fuel to fossil LPG.

Hydrogen is widely applied in the aviation industry as a clean energy source. The hydrogen-air premixed combustion within porous structures has attracted extensive research, which aims to improve the energy conversion efficiency of hydrogen fuel and reduce environmental pollution. However, the accurate prediction of turbulent flame structure and species distribution remains unachieved, due to the disturbance of the random packing structure. In this study, a discrete element method was employed to construct a random packing structure. The large eddy simulation (LES) was adopted to analyze the turbulent flow field. The Eddy Dissipation Concept (EDC) model was employed to simulate the expansion process of the spherical flame in the hydrogen-air premixed gas and accurately predict NOx emissions. It is coupled with a simplified hydrogen-air multiple-step mechanism. To investigate the dynamic evolution mechanism of the flame with the disturbance of the packing structure, the flame surface and vortex structures were extracted by the tracking extraction method (the flame front is dynamically extracted after each time step during combustion progression) and Q-criterion method, respectively. The comparison between the flame radius and propagation velocity simulations obtained from four combustion models and experiments revealed that the EDC model, combined with the multiple-step reaction mechanism, yielded the best agreement with the experimental data. Additionally, four different-sized pellet compositions within the packing structure were compared with the non-porous structure. It indicates that the packing structure composed of pellets with a certain range of sizes increased the vorticity within the reaction zone, reduced the symmetry of the temperature distribution, accelerated the expansion rate of the reaction zone, and decreased NOx emissions. Moreover, it was found that the combustion characteristics and NOx emissions were significantly affected by the packing pellet size. However, when the pellet size reached a threshold, the inhomogeneous structure led to local cavities, resulting in higher NOx emissions than the non-porous structure. This research advances the understanding of hydrogen-air premixed combustion with the influence of packing structure. More significantly, it provides an important theoretical foundation for the application of hydrogen-air porous medium combustion technology in the aviation engine field.

To mitigate carbon emissions from coal-fired power plants while ensuring operational stability, this study numerically investigates the combustion behaviors and pollutant emissions of a 660 MW corner-tangentially-fired boiler under ammonia-coal co-firing conditions (0-60% calorific value ratio) at maximum continuous rating (BMCR). The results show that furnace combustion temperature first increases and then decreases with rising ammonia blending ratio (calorific basis), accompanied by a downward-shifted flame center and concentrated heat absorption in the lower furnace. Notably, 40% ammonia blending achieves the most significant CO2 emission reduction among all ratios, with CO emissions maintained at a manageable level after an initial peak at 10% blending. For NOx emissions, a peak at 10% blending is induced by localized high-temperature zones and primary combustion zone oxygen depletion; however, beyond 20% blending, NOx emissions fall below pure coal combustion levels, driven by reduced thermal NOx formation and enhanced NOx reduction by ammonia-derived nitrogenous intermediates. At 40% blending, unburned ammonia slip remains moderate, avoiding tail flue corrosion and ash deposition risks. This study identifies 40% ammonia co-firing as the optimal full-load condition for the boiler, realizing prominent carbon reduction while balancing combustion stability, pollutant control, and operational safety, and provides valuable engineering insights for ammonia-co-firing retrofit and efficient operation of coal-fired boilers.

In this study, Al-doped Li6.1La3Zr2Al0.3O12 (Al-LLZO) was synthesized via spray evaporation method, followed by calcination and hot-press sintering to produce solid-state electrolyte pellets. Characterization was performed via phase Doppler particle analyzer (PDPA), laser particle size analyzer (LPA), cold field emission scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and distribution of relaxation times (DRT) analysis. The research examined the initial droplet size distribution from atomization, the effect of spray evaporation conditions on the morphology and particle size distribution of both the spray evaporation and calcination powders, and the impact of calcination powder size on electrolyte pellet ionic conductivity. Results shown that spray evaporation powder exhibited a bimodal particle size distribution. The morphology of the spray evaporation powder was dependent on the evaporation temperature and the relative concentration of the precursor solution: higher evaporation temperatures and higher precursor solution concentrations promoted fractured spherical shells, while lower values yielded spherical particles. Calcination powder displayed distinct sintering necks and a unimodal particle size distribution, with larger particles obtained at higher evaporation temperatures and precursor solution concentrations. Increasing calcination powder size enlarged the grain size in the hot-press sintered pellets. At consistent relative density, this grain growth selectively reduced grain boundary resistance while leaving bulk resistance unaffected, thereby enhancing overall ionic conductivity. A maximum ionic conductivity of 2.09 x 10(-4) S/cm was achieved at evaporation temperature of 900 degrees C and a relative precursor solution concentration of 0.9, within the typical range reported for cubic Al-LLZO.

This study develops a novel CFD-DEM coupled DDPM-KTGF method to investigate gas-solid reactions and mass transfer within micro-fluidized bed reactor analyzers (MFBRA). under varying operating conditions. In this approach, the CFD-DEM module captures the formation of emulsion and bubble phases while the DDPM-KTGF module simulates mass transfer effects, enabling a detailed analysis of reaction kinetics. Key findings show that reaction kinetics and mass transfer efficiency are strongly influenced by fluidization states. In the fixed-bed regime, low inlet gas velocities result in constant reaction rates due to high diffusion resistance and limited gas-solid contact. As gas velocity increases and fluidization occurs, mass transfer improves, but further increases lead to bubble coalescence, reducing reaction efficiency. Temperature analysis reveals that at moderate temperatures (700-850 degrees C), mass transfer resistance increases due to enhanced bubble formation, while higher temperatures (850-900 degrees C) improve molecular diffusion but thermodynamic limitations reduce conversion. Moreover, larger particles increase minimum fluidization velocity, promote bubble growth, and reduce catalytic efficiency, with a non-monotonic relationship observed between particle size and conversion rate. Meanwhile, radial mass transfer heterogeneity is non-negligible. This work provides valuable insights into optimizing operating conditions and further enhancing gas-solid catalytic processes within MFBRAs.

Load changes of a circulating fluidized bed (CFB) boiler reconstruct the internal gas-solids flow structure, thereby altering heat transfer and combustion efficiency. To elucidate the dynamic response characteristics of the gas-solids flow in CFB, this study systematically investigates the effects of step changes in superficial gas velocity and solids inventory on solids holdup in the riser and its response behavior, combining cold-state experiments with Computational Particle Fluid Dynamics (CPFD) simulations. The reliability of CPFD for transient processes, largely overlooked in previous studies, was evaluated. Under step changes in superficial gas velocity, the characteristic response time of solids holdup is on the order of tens of seconds. Responses to the superficial gas velocity increase are consistently faster than to decrease, while smaller particle size prolongs the response time. Stepwise increases (10% -> 20% -> 30%) in solids inventory raise the particle solids holdup in the dense phase and shorten the response time. The CPFD model demonstrates strong agreement with experimental data in both solids holdup distribution and dynamic response, with an average simulation error below 5%. The validated workflow establishes a foundation for predicting CFB transients under peak-shaving strategies.