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[Objective]To meet the urgent demand for ultra-low NOx emissions from coal-fired power plants and other energy sectors under the national dual-carbon strategy,this research is dedicated to developing a novel low-temperature manganese-cerium/activated coke(MnCe/AC) catalyst, aiming to provide new materials and theoretical support for achieving efficient and low-carbon flue gas purification. [Methods] This study employs activated coke(AC) with high specific surface area and abundant surface functional groups as a support to prepare MnCe/AC catalysts by incipient wetness impregnation. The effects of different Mn loadings and Mn:Ce molar ratios on catalyst structural properties and DeNOx performance are systematically investigated. [Results] study shows that the MnCe/AC catalyst with 2 wt% Mn loading and Mn∶Ce=2∶1 exhibits the best DeNOx efficiency, reaching 88.5% at 300 ℃, and displays excellent sulfurresistant DeNOx performance and reaction stability with N2 selectivity maintained above 99%. Brunauer-emmett-teller(BET) and X-ray diffraction(XRD) characterization revealed that the catalyst exhibited a specific surface area of 304.77 m2/g, with highly dispersed active metal components. X-ray photoelectron spectroscopy(XPS) analysis indicated that Mn4+ accounted for 63.89% of the total, while surface-adsorbed oxygen constituted 76.12%, providing ample active sites for the catalytic reaction. Furthermore, Hydrogen temperature-programmed reduction(H2-TPR) and ammonia temperature-programmed desorption(NH3-TPD) characterization analyses demonstrated that the synergistic interaction between manganese and cerium metal oxides effectively modulated the catalyst's surface chemistry, significantly enhancing its redox capacity and surface acidity. This endowed the catalyst with outstanding low-temperature catalytic activity, ensuring efficient and highly selective DeNOx reactions at low temperatures. [Conclusion]This study provides theoretical foundations and technical support for developing low-temperature DeNOx catalysts in coal-fired power plants, holding significant value for energy conservation and environmental protection applications.
[Objective]To address the issues of SCR denitrification catalyst deactivation and excessive NOx emissions during the start-up grid connection and deep peak shaving low-load operation phases of thermal power units, this study aims to achieve stable and compliant denitrification at low loads through innovative flue gas temperature regulation and multi-system collaborative optimization methods, providing technical support for flexible peak shaving and environmental protection upgrades of coal-fired units. [Methods]This paper takes a 660 MW ultra-supercritical coal-fired unit as the research subject. Through experiments evaluating the coupled effects of combustion, flue gas, thermal system parameters, and ammonia injection control strategies, a flue gas temperature enhancement technology based on heat distribution optimization of the boiler's tail heating surface is proposed. A multi-variable coupled integration scheme of combustion-flue gas-thermal-ammonia injection is developed, and its engineering application is verified. [Results]The research demonstrates that this technology can significantly improve the unit's start-stop and deep peak shaving capabilities without requiring equipment modifications. After application, the SCR inlet flue gas temperature increased to above 290 ℃ during both post-synchronization and 30% deep peak shaving conditions. The NOx emission concentration remained stably below 50 mg/Nm³, achieving environmental compliance across the full load range. [Conclusion]The study effectively addresses the challenge of denitrification at low loads through the application of low-sulfur coal and systematic flue gas temperature regulation. The technology, validated dozens of times in engineering projects, provides an economical and efficient practical path for similar units and offers new insights for flexibility retrofits and NOx collaborative control in thermal power under the dual-carbon background.
[Objective] When the exhaust gas of the coal-fired unit pulverizing system is transferred, the high-volatile pulverized coal is driven by the exhaust steam at a high speed, and it is easy to form a dust cloud with the participation of oxygen and cause an explosion risk. In order to reduce the deflagration risk of the exhaust gas transfer device of the intermediate storage bunker pulverizing system after the lean coal is changed to bituminous coal, and improve the safety performance of the pulverizing system, it is necessary to set the flow rate and bottom inclination angle of the primary air box reasonably. [Methods] Taking the exhaust gas transfer system of a 330 MW unit in a power plant as the research object, numerical simulation was used to analyze the flow field and temperature field inside the primary air box. The influence of reducing the primary air velocity from 7 m/s to 1 m/s on the devolatilization and enrichment of volatile matter was studied. Meanwhile, 11 types of air box profiles with different bottom inclination angles(α) were designed to compare their flow field optimization effects on the pulverized coal accumulation risk areas. [Results] The research shows that after the exhaust gas is transferred to the primary air box, a low-velocity zone exists at the bottom, which is prone to pulverized coal accumulation. Moreover, the hot air flows downward along the wall to form a local hightemperature zone with a maximum temperature of 329 ℃, exceeding the pyrolysis temperature of pulverized coal(282 ℃), which provides conditions for deflagration. The primary air velocity has a significant impact on the enrichment of volatile matter: when the wind speed decreases to 2 m/s, the CO concentration in the air box reaches its peak. Maintaining a wind speed of 3-7 m/s can balance the devolatilization and carry-over of volatile matter, which is beneficial to system safety. The bottom inclination angle(α) of the air box affects the volume of the low-velocity zone: as α increases, the volume of the low-velocity zone first decreases and then increases, reaching a minimum of 0.132 m3 when α =8.5°. [Conclusion] The research results provide a quantitative basis for the adjustment of operating parameters and structural optimization of the exhaust gas transfer device in the pulverizing system, and have reference significance for the flow field research and potential safety hazard control of similar pulverizing systems.
[Objective] Replacing fossil fuel combustion with ammonia and hydrogen is an effective way to achieve largescale carbon reduction. However, the ignition characteristics and NOx emission control law of ammonia-hydrogen cocombustion need to be further studied. [Methods] In this paper, the ammonia-hydrogen fuel with a total volume of 1 cm3 is taken as the research object, and the kinetic analysis of its co-combustion ignition characteristics is carried out by using Chemkin software. Firstly, the prediction performance of four different chemical reaction mechanisms for ammoniahydrogen co-combustion was compared, and the Anand mechanism was selected as the basis for subsequent analysis of ammonia-hydrogen co-combustion. Secondly, the effects of pressure, temperature, equivalence ratio and hydrogen blending ratio on ignition delay time( IDT) and NOx were analyzed by control variable method. [Results] Studies have shown that the increase of pressure, temperature or hydrogen doping ratio can effectively shorten the IDT. Compared with the initial pure ammonia combustion condition of 0.1 MPa, 1400 K, and equivalence ratio 1.0, IDT decreased from 57.3 ms to 13.0, 7.3, and 5.5 ms, respectively, by increasing the pressure by 0.4 MPa, or increasing the temperature by 200 K, or adding 2.5% hydrogen. Compared with the initial condition, IDT decreased by 77.31%, 87.26%, and 90.40%, respectively. The increase of temperature and hydrogen doping ratio increases the formation of NOx, which is because the addition of hydrogen promotes the formation of OH radicals, which in turn promotes the formation of NO. The increase of equivalence ratio significantly reduces the formation of NOx. On the basis of the initial condition, when the temperature is increased by 600 K, or 80% hydrogen is added, or the equivalence ratio is increased to 1.5, the NOx concentration is increased to 15 092 μL/L, 14 005 μL/L, and decreased to 2 394 μL/L, respectively, compared with the initial condition of 11 138 μL/L, increased by 35.41%, and 28.67%, decreased by 78.51%. In general, the change of equivalence ratio has little effect on IDT in the range of 0.5 ～ 1.5, and the change of pressure has little effect on NOx concentration in the range of 0.1-2.0 MPa. [Conclusion] The research method in this paper can provide a reference for the theoretical simulation of the control of ammonia-hydrogen co-combustion conditions and the measures to reduce pollutants.
[Objective]To address the coordinated optimization of electricity procurement and sales for retailers in diversified electricity markets and achieve a balance between revenue and risk, this study proposes an effective decision optimization model. [Methods]This research develops a diversified market procurement framework covering medium-and long-term contracts, spot markets, green electricity, distributed generation, and energy storage leasing. It designs two basic retail packages: a fixed single electricity price and a time-of-use price. An expected revenue model for the electricity retailer, considering the user selection ratio, is established. By introducing the Conditional Value at Risk method to quantify market risks, a multi-objective decision optimization model aiming at profit maximization and risk minimization for the retailer is constructed. An improved Whale Optimization Algorithm with an adaptive convergence mechanism is employed for efficient solution. [Results]Case study results show that compared to the original algorithm, the proposed improved Whale Optimization Algorithm converges faster and offers higher optimization precision, resulting in a final robust total profit that is 412,000 yuan higher. When the proportion of users on the time-of-use price package ∂=0.2, the retailer achieves the optimal Conditional Value at Risk, with a risk preference factor ρ=5.5, matching a medium-risk procurement strategy. Analysis of the procurement structure reveals that medium-and long-term contracts and green electricity contracts form the stable core of the procurement portfolio. Distributed generation transactions serve as an important flexible supplement, while spot market and energy storage leasing transactions account for very low proportions, reflecting a refined balance between cost and risk. [Conclusion]These results verify the effectiveness of the proposed model and provide the following decision-making basis for the refined operation of electricity retailers: it is recommended that retailers prioritize building a robust procurement structure based on long-term contracts, actively implement demand response policies while ensuring their own profit maximization, and proactively guide users to optimize their package selection structure towards the golden ratio.
[Objective]All-solid-state batteries, known for their high energy density and enhanced safety, are considered a highly promising next-generation energy storage technology. This paper aims to systematically review the progress in key materials and technologies for all-solid-state energy storage batteries, analyze their current challenges and future development directions, and provide references for related research, development, and optimization.[Methods]Through literature review, this paper first elaborates on the fundamental principles and research challenges of all-solid-state batteries. It systematically evaluates the research status and modification strategies for three key material categories: cathode, electrolyte, and anode, with a focus on the characteristics of oxide, sulfide, and polymer electrolytes, as well as LiCoO2, high-nickel ternary, and LiFePO4 cathodes, along with lithium metal, silicon, and carbon-based anodes. Furthermore, from the perspectives of key technologies such as interface engineering, structure and process optimization, and safety and cycle life enhancement, it discusses interface failure mechanisms and control strategies, fabrication processes such as multilayer stacking, hot pressing, and cold sintering, as well as strategies for lithium dendrite suppression and thermal runaway prevention.[Results]Analysis shows that strategies such as element doping, interface coating, composite structure design, and advanced manufacturing processes can effectively enhance the ionic conductivity of solid electrolytes, improve electrode/electrolyte interface stability, and suppress lithium dendrite growth, thereby improving the overall performance of all-solid-state batteries. The cited research works demonstrate significant progress in material modification and interface optimization.[Conclusion]All-solid-state batteries have broad application prospects in fields such as electric vehicles and high-end consumer electronics. However, their large-scale commercialization still faces challenges such as interface impedance, cost, and manufacturing processes. Future efforts require interdisciplinary collaboration and synergistic innovation in technologies such as materials genomics, artificial intelligence, advanced characterization, and simulation to drive the research, development, and industrialization of highperformance, safe, and low-cost all-solid-state batteries.
[Objective] To investigate the mechanism by which the fuel change gradient during transition states affects combustion instability in swirl flames. [Methods] In this study, a single-stage axial swirl propane diffusion flame model combustor was numerically simulated using Large Eddy Simulation(LES) coupled with the Flamelet Generated Manifolds(FGM) combustion model. Three different fuel change gradients(k = ∞, 1.54, 0.77) were examined to analyze the flow and combustion processes. [Results] Steady-state flow field analysis confirmed that the central recirculation zone and corner recirculation zones are critical for flame stabilization. Transient simulation results demonstrated that the fuel change gradient has a decisive influence on both the transition process and the final state: under the step transition condition(k = ∞), the complete transformation of the flame morphology from an elongated to a short, drum-like shape exhibited a delay of approximately 40 ms. In all transition cases, the time-averaged temperature at the final state was higher than that of the steady control group without transition, and the temperature increased with the fuel change gradient. Specifically, under the step transition condition(k = ∞), the terminal state temperature at the outlet of the combustion chamber is 100 K higher than that of the steady-state control group without transition. The energy of the dominant Proper Orthogonal Decomposition(POD) mode, which characterizes combustion instability, increased significantly with the fuel change gradient and reached its maximum under the step transition condition(k = ∞). [Conclusion] The study confirms that a larger fuel change gradient introduces stronger unsteady disturbances into the combustion system, thereby significantly increasing the risk of triggering combustion instability.
[Objective] To address the volatility and intermittency of renewable energy generation, Compressed Air Energy Storage(CAES) technology has emerged as a key solution. Depleted oil and gas reservoirs are increasingly recognized for their potential as CAES gas storage sites. However, related research is limited, necessitating an assessment of existing technologies and future development directions to resolve core application challenges. [Methods] A comprehensive analysis of existing literature was conducted. The study focused on core issues concerning CAES in depleted reservoirs, including cushion gas selection, wellbore sand production, and geological conditions/site selection. The impacts of different cushion gases, key factors influencing sand production, and the role of geological conditions on system performance were investigated. Existing technological advancements were also reviewed. [Results] Depleted oil and gas reservoirs offer significant advantages as CAES storage sites, eliminating the need for cavity creation and utilizing existing wellbores to reduce costs. Their cushion gas ratio(50%-60%) is lower than that required for aquifers. Nitrogen and carbon dioxide each have merits and drawbacks as cushion gases: nitrogen mixes easily with the working gas, while CO2 offers better compressibility but may react with the formation. Wellbore sand production is significantly influenced by cyclic loading, water content, and pressure, with high-frequency injectionproduction cycles exacerbating the risk. Geological factors such as formation depth, structure, and porosity impact system efficiency. Existing evaluation systems require optimization to address the characteristics of CAES highfrequency cycling. [Conclusion] Depleted oil and gas reservoirs hold great potential for CAES. Future research requires deepening the comprehensive optimization of cushion gases, overcoming challenges related to wellbore safety and modeling under high-frequency cycling, refining targeted site selection evaluation systems, and developing multi-physics coupled simulation technologies to investigate the complex effects of high-frequency cycling on the reservoir formation.
[Objective] The flow field uniformity of the denitration system of coal-fired units has an important influence on the denitration efficiency. In order to improve the problem of uneven distribution of flow field in flue gas denitrification system of large coal-fired power units, it is necessary to optimize the flow field of denitrification flue. [Methods] In this paper, a dynamic guide vane structure optimization scheme is proposed. The computational fluid dynamics numerical simulation method is used to construct a three-dimensional geometric model including inlet flue, guide plate and rectifier device for the selective catalytic reduction denitrification flue of a 350 MW coal-fired boiler. The standard k-ε turbulence model and porous medium model are used for simulation analysis. [Results] The simulation results indicate that the original flue exhibited pronounced flow separation, recirculation, and large-scale vortical structures in the expansion section and multiple bends, leading to a highly non-uniform velocity distribution at the catalyst inlet, with a velocity deviation coefficient of 40.6% and more than 30% of the cross-section occupied by low-velocity regions. Comparative analysis of the four optimization schemes shows that the combined application of dynamic guide vanes and adjustable throttling plates effectively improves the flow path in the bend region, suppresses local high-velocity impingement, and significantly reduces low-velocity stagnant zones. Among the evaluated cases, the optimal scheme(Scheme 4) reduces the velocity deviation coefficient to 13.2%, increases the proportion of medium-velocity regions to 75%, and simultaneously decreases the overall pressure drop by approximately 5%-7% compared with the original configuration. In addition, the distribution of fly ash concentration and guide-vane erosion becomes more uniform, demonstrating comprehensive improvements in flow uniformity, hydraulic performance, and wear resistance. [Conclusion] This research validates the practicality and feasibility of dynamic guide vanes technology in optimizing SCR denitrification systems, providing a theoretical basis and engineering reference for enhancing denitration efficiency, controlling ammonia slip, and extending catalyst service life.