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Design and research of modified active disturbance rejection control for denitration system
JIN Fangzhou;SHI Gengjin;SUI Shaoyong;WU Zhenlong;Wuhu Power Generation Co. Ltd.;China Power International Development Limited;Rundian Energy Science and Technology Co.Ltd.;[Objective]To address the problems of dynamic response lag and insufficient anti-interference capability of the denitrification system of coal-fired units under rapid load fluctuation conditions, an improved error-based active disturbance rejection control(EADRC) strategy is proposed to improve the tracking performance and anti-interference capability of the denitrification system in terms of the exported NOx concentration tracking performance and antiinterference capability of the denitrification system. [Methods]First, the strong nonlinear characteristics of the denitrification system are quantitatively analysed by the gap metric method. Secondly, the structure of the self-immunity controller is reconstructed, and the tracking error is used as the definition of the state variable to derive the EADRC control law(including the expanded state observer and the error feedback mechanism), and to configure the observer and the controller poles. The performance of PI, ADRC and EADRC under steady state/variable load conditions is compared by simulation, and the robustness is verified based on Monte Carlo experiments; finally, it is verified by industrial application in a 660 MW unit denitrification system. [Results]The simulation shows that the tracking performance of EADRC is 49.5% higher than that of PI, and the cumulative error is reduced to 2.059 4×103, with comparable anti-interference performance, while the tracking performance is 60.7% higher than that of ADRC, although the anti-interference performance decreases by 26.55%, and the ammonia escape is the lowest. In the field application, EADRC reduced the NOx fluctuation range by 55.71%, and the average hourly IAE value decreased from 4.17×104 to 1.84×104. [Conclusion]EADRC effectively balances the tracking performance and anti-interference capability, has a simple structure, is easy to implement in engineering, is suitable for the strong nonlinear scenario of the denitrification system, and provides a new solution for efficient control under deep peaking of coal-fired units.
Research advances in key materials and technologies for all-solid-state energy storage batteries
HUANG Jing;YUAN Wenlu;WANG Tao;[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.
Numerical simulation study on ignition and NOx emission characteristics of ammonia-hydrogen co-combustion
WANG Yankai;HU Jiale;ZHANG Gengyu;MU Zhengxi;XIONG Xiaohe;[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.
Study on the effect of different MnCe loadings on the performance of active coke carrier catalysts in medium and low-temperature NH3-SCR
HUANG Shuo;XU Yun;ZHANG Qian;ZHANG Yaoyu;SHENG Zhongyi;YANG Liu;[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.
Numerical simulation of full-furnace denitration in a circulating fluidized bed under low-load conditions
MEI Jiawei;YAN Gaocheng;[Objective] At low load, the circulating fluidized bed has the problem of low denitration efficiency in the furnace. In order to solve this problem, it is necessary to study the law of ammonia injection and denitrification in circulating fluidized bed at a specific low load. [Methods] Computational Fluid Dynamics(CFD) numerical simulation was employed to investigate the effectiveness and feasibility of in-furnace denitration within a 350 MW supercritical CFB boiler. The research primarily consisted of three parts: firstly, comparing and analyzing the impact of ammonia injection via nozzles installed at different locations—the coal feed port, upper/lower secondary air ports(front wall), and return material port on denitration efficiency to determine the optimal injection location; secondly, studying the influence of the ammonia-to-nitrogen molar ratio(NSR) on both denitration efficiency and ammonia slip; finally, analyzing the effect of the injection velocity on denitration performance. [Results] The results show that :(1) The coal feeding port is the best ammonia injection position, and its denitration efficiency is 4.4%, 2.4% and 12.9% higher than that of the upper secondary air outlet, the lower secondary air outlet and the return port, respectively.(2) When the molar ratio of ammonia to nitrogen increased from 1.0 to 1.5, the denitrification efficiency increased by 13 percentage points. At this time, the denitrification efficiency was 58.5%, and the ammonia escape was 7.6 mg/m3. When the molar ratio of ammonia nitrogen is further improved, the improvement of denitrification efficiency tends to be stable, and the ammonia escape concentration exceeds the standard.(3) The denitrification efficiency increases with the increase of ammonia injection speed. When the injection speed increases to 80 m/s, the NOx concentration decreases to 45.8 mg/m3, and the denitrification effect is the best. [Conclusion] Through full-furnace CFD simulation of the 350 MW supercritical CFB boiler under low-load conditions, this study identified the optimal ammonia injection location, NSR, and injection velocity. It provides a new approach and theoretical foundation for achieving efficient and stable denitration in CFB boilers operating under low-load conditions.
Optimization of flow field in coal-fired boiler denitrification system using adjustable deflectors
LI Chong;YAN Gaocheng;WANG Xing;[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.
Research and application of SCR full-load denitrification technology based on multivariable coupling
QIANG Jun;YU Jiajun;CAI Xizhong;HONG Buqiang;WANG Xin;[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.
Numerical simulation of NOx emission characteristics of ammonia-coal co-combustion in 350 MW circulating fluidized bed boiler
HUANG Mengtao;YAN Gaocheng;[Objective] To promote the low-carbon transformation of coal-fired power units, ammonia-coal co-firing technology has become an important research direction for emission reduction in coal-fired power generation. [Methods] Based on computational fluid dynamics(CFD), this study performed numerical simulations of the ammonia-coal co-combustion process and pollutant emission characteristics in a 350 MW circulating fluidized bed(CFB) boiler. First, the ammonia injection position was optimized by comparing the combustion and NOx emission characteristics at three different injection points: the upper secondary air port, lower secondary air port, and coal feeding port. Then, the effects of ammonia blending ratios(0%, 10%, 15%, and 20%) on furnace combustion and NOx emissions were analyzed. Finally, the influence of the excess air ratio on ammonia-coal co-combustion characteristics was examined. [Results] The results show that:(1) The best ammonia injection position is the coal inlet, and the NOx emission concentration is 12.5% and 9.4% lower than that of the upper and lower secondary air outlets, respectively, and the minimum ammonia escape concentration is 4.5 mg/m3;(2) The optimal blending ratio of ammonia coal is 15%. At this time, the NOx emission is about 3% higher than that of pure coal combustion, the furnace temperature decreases by about 30 K, and the ammonia escape concentration remains at a low level.(3) The optimum excess air coefficient is 1.25, and the co-combustion state of ammonia and coal is the best. [Conclusion] Through numerical simulations of the ammonia-coal co-combustion process and pollutant emissions in a 350 MW supercritical CFB boiler, this study determined the optimal ammonia injection position, blending ratio, and excess air ratio, providing a theoretical reference for the low-carbon retrofit of circulating fluidized bed boilers.
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Introduction
Electric Power Technology and Environmental Protection
Bimonthly issued
CN 32-1808/X
ISSN 1674-8069
Governed by:
China Energy Investment Group Co., Ltd.
Sponsored by:
China Energy Group Science and Technology Research Institute Co., Ltd.
Academic support：
State Key Laboratory of Low-carbon Smart Coal-fired PowerGeneration and Ultra-clean Emission
Columns:
Thermal Energy Engineering, Clean Power Generation, New Energy Generation, Integrated Power Generation.
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