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Chemical Kinetics Simulation on Nitrogen Migration Characteristics During Co-Combustion of Ammonia and Coal Under Deeply Fuel-Air Multistage Conditions

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SSRN 2024年

作者： Dai, Liangxu Wang, Chang'an Hou, Yujie Ma, Guowei Chen, Yongxu Hurera, Abu Zhou, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China China Energy Science and Technology Research Institute Co. Ltd. Nanjing210046 China

mmonia, a carbon-free fuel, is attracting an ever-increasing attention. Coal/ammonia co-combustion in coal-fired power plants is considered an effective and fast approach to achieving the global decarbonization goal. However, one bottleneck of the utilization of ammonia fuel is the possible increased NOx emissions. The supply strategy of ammonia can affect the reduction of NOx by NH3. Few studies have explored the influence of ratios of ammonia as a secondary fuel and the secondary air volume on NOx emissions, which could be effective methods to reduce pollution. In this work, a chemical kinetics model was established to study the NOx behaviors during coal/NH3 co-firing in deeply fuel-air multistage conditions. The effects of the ammonia distribution strategies such as the ratio of NH3 as a secondary fuel, the injection position of secondary fuel, and corresponding air distribution with different NH3 co-firing ratios (CR-NH3) on the ammonia reactivity for NOx-reduction were studied. The results show that ammonia should be used as a primary fuel entering the main combustion zone under small CR-NH3 conditions to mitigate the NOx emissions;otherwise, ammonia is inclined to be used as a secondary fuel entering the reduction zone under large CR-NH3 conditions. NOx generation is also found to primarily occur in the burnout zone in fuel-air multistage combustion. Thus, the burnout zone should be given priority to decrease the NOx emissions. With the delay of secondary fuel injection in the reduction zone, the escaping ammonia keeps increasing in the outlet of the reduction zone. Then it is completely burned in the burnout zone, which leads to an increase in NOx emissions. The volume flow rate of NOx shows a downward trend on the whole with the ratio of secondary air increased. The air distribution can alter the function of the reduction zone in both generating and eliminating NO. The findings can provide some guidance to effectively decrease NOx emissions in coal/NH3 co-fi

关键词： Coal

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Development of typical processes and key devices for direct air CO2 capture

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Meitan Xuebao/Journal of the China Coal Society 2024年第10期49卷 4203-4221页

作者： Yu, Binpeng Tan, Lei Wang, Ding Wang, Limin Xiang, Xiaofeng Wang, Zhichao Jin, Zhonghua Yang, Bolun Wu, Zhiqiang School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China Shaanxi Province Energy and Chemical Process Intensification Key Laboratory Xi’an710049 China School of Engery and Powerl Engineering Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an710049 China Shaanxi Engineering Research Center if Coal Fired Boiler Environmental Protection Xi’an710054 China

Conventional carbon capture and storage technologies and carbon capture, utilization and storage technologies mainly target CO2 emissions from fixed sources, while direct air capture CO2 (DAC) technology, as an emerging negative carbon emission technology, can capture CO2 emissions from distributed sources and further reduce the global atmospheric CO2 concentration. In this paper, the development process of DAC's typical liquid absorption process, solid adsorption process and the construction of relevant demonstration projects are introduced, the technical characteristics of emerging DAC processes are analyzed, and the key equipment schemes and future development trends of existing DAC processes are discussed. The DAC liquid absorption process has the characteristics of low cost of absorbent raw materials and high selectivity, which can realize a large-scale continuous capture, but high energy consumption in the regeneration process. The DAC solid adsorption process has the characteristics of modularity, low investment cost, and relatively low energy consumption in the regeneration process, but requires a regular replacement of adsorption materials and maintenance of adsorption equipment, which is suitable for small-scale DAC application scenarios. Two typical DAC process absorption/adsorption materials are reviewed. In the DAC electric oscillation adsorption process, CO2 is chemically captured in the solid electrode, and CO2 desorption is achieved by changing the polarity of the solid electrode with applied electric field. This process has a higher efficiency than that of the heat or pressure-based separation process. The CO2 in the air is selected through the DAC separation membrane to achieve an efficient carbon capture. The DAC process achieves the CO2 absorption and desorption through the change of humidity, which breaks through the high energy consumption limit of conventional variable temperature/pressure swing adsorption. The DAC bio-absorption process absor

关键词： Adsorption

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Waste heat recovery in the coal-fired power generation integrated with post-combustion

Waste heat recovery in the coal-fired power generation integ...

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Electrical engineering and Mechatronics Technology (ICEEMT), IEEE International Conference on

作者： Yali Yang Guiwen Wang Yan Li Yongping Liu Yue Fu Ming Liu Guoneng Jinjie Energy Co. Ltd Yulin China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

Post combustion systems (PCS) are a viable technology option to reduce carbon dioxide in the electricity production. However, the energy-intensive of PCC precludes its wide scale application. As for the optimization of the post combustion system, there is an optimal inlet temperature of the stripper. By optimizing the parameter of the post combustion system, the energy consumption rate of the post combustion system decreased by 1.4 GJ/t CO 2 under 100% THA compared to the original post combustion system. The needed heat by the stripper shows a fall with the decrease of the unit load ratio. However, the heat changes of the post combustion system decrease with the decrease of the unit load ratio under 90% absorption rate. The efficiency penalty can be as low as 4.1% through waste heat recovery.

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An inverse fault detection and diagnosis (IFDD) strategy for practical application on chiller product

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INTERNATIONAL JOURNAL OF REFRIGERATION 2022年 134卷 24-34页

作者： Lu, Hailong Cui, Xiaoyu Han, Hua Liu, Jiangyan Zhang, Yunqian [a]School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Yangpu District Shanghai 200093 PR China [b]Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 PR China [c]CQ Midea General Refrigeration Equipment Co. Ltd. 15 Qiangwei Road Nanan District Chongqing 401336 PR China [d]School of Energy and Power Engineering Chongqing University Chongqing PR China

Current research on chiller fault detection and diagnosis (FDD) is usually based on the multi-classification method for mixed multiple fault types. The establishment of a multi-classification FDD model requires obtaining extensive test data of normal operation and multiple common faults at different fault levels, so the cost-to benefit ratio will not be accepted. In addition, because of the information interference between different types of fault data, FDD model is hard to avoid over-fitting or under-fitting, and there may be an intolerable high false alarm rate existing in product application. Therefore, it is difficult to promote FDD in actual chiller product applications. This paper proposes an inverse fault detection and diagnosis (IFDD) strategy, which is based on the characteristics of the target fault (the fault to be concerned) to establish a two-classification fault diagnosis model. Compared with the multi-classification method, the amount of fault test data required by the two classification methods to realize fault diagnosis can be greatly reduced. With IFDD strategy, the detection and diagnosis are completed simultaneously, while fast calculation speed, high diagnosis accuracy rate and low false alarm rate are achieved. The core of the IFDD strategy is to concentrate resources to capture the characteristics of the target fault, and no longer classify other types of faults and normal operating conditions, so it can avoid the influence of information interference between multiple types of fault data in the fault diagnosis model. In order to verify the feasibility of this strategy, a 200 ton variable-speed screw chiller has been tested on the laboratory, and a database of normal operation, refrigerant leakage, refrigerant overcharge faults, and a new operating condition of insufficient cooling water flow is initially established. Based on the sensors configured by the chiller unit and using the exponentially weighted moving-average (EWMA) control chart for

关键词： Inverse FDD Strategy Practical application Chiller product EWMA

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Numerical Investigation on the Thermal-Hydraulic Performance of a Cryogenic Printed Circuit Heat Exchanger for Liquid Air Energy Storage

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SSRN 2022年

作者： Yu, Pengfei Liu, Hu Xue, Jingwen Zhang, Yankang Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'An710049 China

The liquid air energy storage integrated with liquefied natural gas regasification is a promising large-scale storage method, but its development is limited by the lack of the thermal-hydraulic data of the cryogenic printed circuit heat exchanger. In this paper, a reduced numerical model for conjugate heat transfer was established, and the effect of the inclined angle (0°, 15°, 30°, 45°, and 60°) was investigated. The minimum internal temperature approach for optimal system operation is approximately 6 K, located in the middle of the heat exchanger. The nature of local flow and heat transfer was analyzed by quantifying the vortex strength and visualizing the vortex core. Results indicate that the evolution of Dean vortices plays a crucial role in heat transfer augmentation. The secondary flow caused by the elbow forces the velocity and temperature cores to strike the windward side periodically, which disturbs the boundary layer and enhances the fluid mixing. Entropy production analysis shows that the thermal entropy generation has a dominant share of the irreversibility. The zigzag channel with an inclined angle of 45° yields the best comprehensive performance since the irreversibility is reduced by augmenting the heat transfer. © 2022, The Authors. All rights reserved.

关键词： Air

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Numerical Investigation on Combustion Characteristics and NOx Emission of Double-Reheat Tower Boiler at Different Loads 9th

Numerical Investigation on Combustion Characteristics and NO...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Zhang, Yan Ma, Shihao Guo, Jin Li, Yuesheng Zhu, Zhengrong He, Jiaqi Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China Guangdong Institue of Special Equpiment and Research Foshan528251 China Guangdong Institue of Special Equipment Inspection and Research Shunde Institue of Inspection Foshan528300 China

ISBN: (纸本)9789811616563

In this study, a three-dimensional numerical investigation using a finite volume method is presented to obtain the velocity, temperature, and species distributions in a 660 MW double-reheat tower boiler fed with bituminous coal. The refined oxidation model of HCN and NO-char reaction model were used to substitute the default model by the user-defined functions (UDFs). The effects of different loads and excess air ratios on combustion characteristics and NOx emission were studied numerically. The results show that temperature distribution is more uneven at the upper part of the furnace and the NOx emission increases as the load decreases. The temperature distributions in the furnace have little differences under three different excess air ratios. That the oxygen concentration increases significantly as the increase of excess air ratios leads to an increase of NOx emission at the furnace outlet. The minimum NOx concentration at the furnace outlet, 308 ppm, appears under 100% THA with excess air ratio of 1.15. The simulation results in this study can provide reference for optimization of combustion characteristics in double-reheat tower boiler and illustrate a method to reduce NOx emission. © 2022, Tsinghua University Press.

关键词： Furnaces

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Water Washing of Biomass and Biochar

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SSRN 2022年

作者： Huang, Xiaole Tie, Yuan Jiang, Jiahao Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

To investigate the differences of organics composition between leachates of biomass and biochar, four biomass materials and the corresponding biochar are water washed. The distributions of organic compounds in leachates are characterized by GC-MS. Raw and washed biomass, and biomass leachates dried at 333 K are sent for TG/DTG analysis. The results show that considering the content of aromatic hydrocarbons, corn and sorghum stalk are referred to be washed after high-temperature pyrolysis at 303 K, with the value of 11% and 29.95% respectively. Wheat straw and rice husk are proposed to wash directly. Considering the alkanes, cycloalkanes and heterocyclic hydrocarbons contents in leachates, it is proposed to washing low-temperature pyrolyzed biochar. It is recommended to wash biomass directly to inhibit acidic organics release. Washed and raw biomass have similar DTG curves. The combustion stage of dried leachate is more complicated, with one or two peaks during the third stage. The activation energy follows an order of washed biomass > raw biomass > biomass leachate. © 2022, The Authors. All rights reserved.

关键词： Biomass

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The Performance Study on Hydrogen Production From Medium Temperature Methane Chemical Looping Steam Reforming Using Lithium-based Absorbent

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2025年第5期46卷 1401-1408页

作者： Wang, Xuyun Li, Yang Gai, Zhongrui Rao, Qiong Liu, Mingkai Pan, Ying School of Engineering Science University of Science and Technology of China Hefei230027 China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Lithium silicate serves as a novel CO2 absorbent with moderate absorptionregeneration temperature range (500∼700◦C) and excellent cycling stability. In this study, Li2CO3 was selected as the precursor for the preparation of lithium silicate. Additionally, a eutectic co-doping method with potassium elements was employed to enhance its reactivity. Using extrusion-spheronization, we successfully produced absorbent particles with high mechanical strength and cycling stability. The effects of absorption-regeneration temperature, CO2 concentration and particle diameter on the performance of absorbent particles have been studied in detail. Furthermore, mixed with NiO oxygen carriers, sorption-enhanced chemical looping reforming (SE-CLR) experiments were conducted at the range of 500∼650◦C for hydrogen production and in situ CO2 capture factors such as reaction temperatures and oxygen carrier to absorbent mass ratios were then investigated The results showcase that at the optimal reaction temperature of 600◦C, the SE-CLR process effectively lowered the reaction temperature by 25◦C, achieving a 13% increase in methane conversion rate and hydrogen purity and CO2 capture rate above 90% were attained. © 2025 Science Press. All rights reserved.

关键词： Silicates

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Integrated Co2 Capture and Conversion by Three-Step Chemical Looping Dry Reforming of Methane

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SSRN 2025年

作者： Liu, Yunlian Liu, Mingkai Shen, Yuanhui Li, Yang Gai, Zhongrui Zhang, Ruqi Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The integrated CO2 capture and conversion (ICCC) has emerged as a promising and cost-effective pathway for achieving carbon neutrality. However, limited energy-efficient pathways and durable materials for ICCC systems remains challenging. This study proposes a novel approach that synergistically integrates CO2 capture and conversion through a unified chemical framework. The method employs Li-based sorbents for CO2 capture, coupled with CH4-driven sorbent regeneration that is seamlessly integrated with chemical looping dry reforming of methane (CLDRM), enabling in-situ CO2 conversion. By coupling sorbent regeneration with CLDRM, this system enhances decarbonation kinetics through Le Chatelier's principle via continuous CO2 conversion. One-step calcination synthesized Li-based sorbents particles exhibit stable CO2 capture capacity of 5.25 mmol·g-1 within 15 min per cycle, maintaining 7.5-15% operational efficiency over 40 cycles at 600 ℃. In CLDRM, hydrogen radicals from CH4 dissociation promote the conversion of CO2 to intermediates, lowering the apparent activation energy of sorbents regeneration by 29.2%. Through systematic optimization in a fixed-bed reactor, we achieved 90% CO2 uptake and 85% CH4 conversion, with syngas production rates reaching 13.71 mL·min-1·g-1. Notably, the H2/CO molar ratio in syngas stabilizes ~1.6, aligns with iron-based Fischer-Tropsch and methanol synthesis to produce valuable fuels. This integrated system maintains >80% syngas purity with © 2025, The Authors. All rights reserved.

关键词： Activation energy

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Water Washing of Biomass and Biochar

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SSRN 2022年

To investigate the differences in organics composition between leachates of biomass and biochar, four biomass materials and the corresponding biochar are water washed. GC-MS is employed to characterize the distributions of organic components in leachates. Raw and washed biomass, and biomass leachates dried at 333 K are sent for TG/DTG analysis. The results show that corn and sorghum stalks should be washed after the high-temperature pyrolysis at 303 K, with aromatic hydrocarbon contents of 11.00% and 29.95%, respectively. It is proposed that wheat straw and rice husk should be washed directly. Considering the contents of alkanes, cycloalkanes, and heterocyclic hydrocarbon in leachates, biomass should be pyrolyzed at a relatively low temperature and then be washed. It is recommended to wash biomass directly to inhibit the acidic organic release. Washed and raw biomass samples have the similar DTG curves. The combustion of dried leachate is more complicated, with one or two peaks during the third stage. The activation energy follows an order of washed biomass > raw biomass > biomass leachate. © 2022, The Authors. All rights reserved.

关键词： Biomass

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