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    Research & Analysis
  • Research & Analysis
    Evolution of Particle Size and Morphology During Pulverized Biomass Combustion
    Yang Shuzhen, Jiang Lüxiao, Sheng Changdong
    2021, 35(1): 1-9. https://doi.org/10.19806/j.cnki.fdsb.2021.01.001
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    Size and morphology evolution during combustion of pulverized rice husk, wheat straw and corn stalk of 250-300 μm were studied, while the influences of pyrolysis and combustion conditions were investigated. Results show that the morphology of pulverized biomass particles is significantly different even for the same kind of biomass, and the morphology changes at different degrees after pyrolysis and combustion. Shrinkage and fragmentation of the pulverized biomass particles during pyrolysis lead to the reduction of the equivalent diameter by 9%-59%, depending on the biomass category and combustion conditions. The variations of the parameters describing the particle morphology, such as the aspect ratio, circularity and roundness, are relatively small by only 2%-28%, which are affected by the biomass species as well as the particle fragmentation, melting and conglomeration during pyrolysis and combustion. The influence of pyrolysis temperature on the variation of particle size is greater than that on the variation of morphology, and the influence of combustion temperature and environment on the variation of each parameter is realized through their actions on the particle fragmentation, melting and conglomeration.
  • Research & Analysis
    Study on Steam Temperature Adjustment of a 1 100 MW Reverse Dual-circle Tangential Firing Boiler
    Gong Shishang, Chen Lu, Han Huafeng, Zhu Lei, Chen Tiefeng
    2021, 35(1): 10-16. https://doi.org/10.19806/j.cnki.fdsb.2021.01.002
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    To solve the problem of low steam temperature existing in an ultra supercritical unit with reverse dual-circle tangential firing boiler, the effects of the following factors on the main steam and reheat steam temperature were studied under the premise that the wall of the superheater and reheater is not overheated, such as the swing angle of burner, the volume fraction of operating oxygen, the flow rate of burnout air, the opening of flue gas baffle, the flow rate of primary air, the distribution mode of secondary air and the way of soot blowing optimization, etc., after which, comprehensive optimizations and adjustments were carried out. Results show that the main steam temperature and reheat steam temperature can both reach their design values after above factors are adjusted simultaneously, indicating good adjustment effect. This may serve as a reference for steam temperature adjustment of similar units.
  • Research & Analysis
    Numerical Simulation and Experimental Research on Staged Combustion in a 600 MW Tangentially-fired Boiler
    He Rongqiang, Li Debo, Zheng Guo, Zhou Jielian, Feng Yongxin, Chen Tuo, Liao Hongkai, Cheng Mingtao
    2021, 35(1): 17-21. https://doi.org/10.19806/j.cnki.fdsb.2021.01.003
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    To solve the problem of high NOx concentration at the furnace outlet of a 600 MW tangentially-fired boiler, the two-stage combustion technology was adopted, based on which, simulation optimizations and field tests were conducted on the combustion characteristics of the boiler. Results show that the two-stage combustion technology has a significant effect on the oxygen content in the burnout zone. After taking combustion adjustments, the boiler efficiency remains unchanged, the carbon content in both the fly ash and the slag keeps stable, and the flue gas gets evenly mixed in the upper furnace.
  • Research & Analysis
    Influence of Air-Powder Distribution Deviation on Combustion Characteristics of the Boiler
    Lin Hua
    2021, 35(1): 22-26. https://doi.org/10.19806/j.cnki.fdsb.2021.01.004
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    Taking the boiler in a 660 MW ultra-supercritical coal-fired unit as an object of study, the influence of air-powder distribution deviation on the combustion characteristics of the boiler was analyzed based on calculation results and operation data. To balance the air-powder distribution among different parallel ducts, a reducer was added to adjust the resistance. Results show that the resistance deviation in air-powder ducts would lead to uneven combustion in the furnace and large deviation of flue gas temperature at the outlet. After the adjustment of resistance in the air-powder ducts, the deviation of coal powder concentration is reduced, the outlet flue gas temperature is evenly distributed, simultaneously with enhanced combustion stability in the furnace, and improved operation stability and safety of the unit.
    • New Energy
  • New Energy
    Benefit Analysis of a Photovoltaic Power Plant Based on Genetic Algorithm
    Jiang Daijun, Hu Shunli, Hu Xiaojian, Fan Xuan, Fan Zun, Zhao Dandan, Wang Jun
    2021, 35(1): 27-31. https://doi.org/10.19806/j.cnki.fdsb.2021.01.005
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    A cost-benefit analysis was conducted on a photovoltaic power station over the whole life cycle using the global searching capability of genetic algorithm. On the basis of simulation, the accuracy of the model established was verified with actual measurements. Results show that the cost-benefit analysis based on genetic algorithm can help to optimize the capacity scheduling for the components in the photovoltaic power station, thus to maximize the benefits of the system.
  • New Energy
    Study on the Performance of Semiconductor-ion Nanocomposite Electrolyte Materials GDC-LCNC
    Dong Ting, Yang Fan, Zhang Xixin, Tian Wentao, Liu Jingjing, Zhang Yifei
    2021, 35(1): 32-35. https://doi.org/10.19806/j.cnki.fdsb.2021.01.006
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    Semiconductor ionic nanocomposite electrolyte materials GDC (Gd0.9Sm0.1O1.95)-LCNC (LiCo0.225Ni0.7Cu0.075O3-δ) with high ionic conductivity were prepared, while the effects of the mass ratio between GDC and LCNC on the performance of the fuel cell were studied. Results show the fuel cell with pure GDC electrolyte has the worst performance without current. When the mass ratio is 2:1, the maximum power density would be 223 mW/cm2. Optimum comprehensive performance is to be obtained for the cell at the mass ratio of 3:1, when the current density does not reduce significantly within a short time (4 h) at the constant voltage of 0.45 V, indicating good performance of the GDC-LCNC.
    • Material Technology
  • Material Technology
    Effects of Aging Temperature and Alloy Composition on Ordering Transformation of Ni-Cr-Fe Alloys During Isothermal Aging
    Ru Xiangkun, Lü Zhanpeng, Yang Chengdong, Ma Jiarong, Yuan Qian, Tang Weibao
    2021, 35(1): 36-41. https://doi.org/10.19806/j.cnki.fdsb.2021.01.007
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    Long-range ordering (LRO) transformation of Ni-Cr-Fe alloys during aging treatment was investigated at 360 ℃, 400 ℃ and 500 ℃. Results show that the rise of aging temperature helps to shorten the ordering incubation period and increase the ordering transformation rate. The ordering transformation of binary Ni-Cr alloys could be promoted at the Ni/Cr atom number ratio of about 2:1. Compared with the Ni-Cr alloys, the ordering transformation speed of ternary Ni-Cr-Fe alloys is lower at the number fraction of Fe atoms of 1%, with obviously elongated ordering incubation period, which could be further elongated at the number fraction of Fe atoms of 3%.
  • Material Technology
    Cause Analysis and Countermeasures for HR3C Slider Weld Cracks in the High-temperature Reheater of a 1 000 MW Unit
    Wang Haimei, Gao Peng
    2021, 35(1): 42-45. https://doi.org/10.19806/j.cnki.fdsb.2021.01.008
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    To solve the problem of weld cracks existing in the HR3C slider for the high-temperature reheater in a 1 000 MW unit, sampling tests and field examinations were performed to analyze the causes. Results show that the cracks are found to be caused by the embrittlement in the HR3C steel along grain boundaries after long-term services.
  • Material Technology
    Life Assessment of a Low Hardness Elbow for the P91 Main Steam Pipe
    Zhang Yongjun, Zhang Weini, Wang Zheng, Wang Yanfeng
    2021, 35(1): 46-48. https://doi.org/10.19806/j.cnki.fdsb.2021.01.009
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    Microstructure analysis and life assessment were conducted on an elbow of low hardness for the P91 main steam pipe in a thermal power unit. Results show that the microstructure of the elbow is majorly composed of ferrite and carbide, and the precipitated phases are mainly made up of Cr23C6 and Mo-rich Laves. The residual life of the elbow is expected to be 5.47×104 hours when it runs at 541 ℃ and 17.5 MPa.
    • Nuclear Technology
  • Nuclear Technology
    Seismic Qualification and Analysis of a Main Control Console in a Nuclear Power Plant
    Ge Lei, Zhao Yong, Lu Xing
    2021, 35(1): 49-52. https://doi.org/10.19806/j.cnki.fdsb.2021.01.010
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    Finite element analysis was used to study the structural integrity of a main control console in a nuclear power plant under seismic conditions, while transient seismic response of the console was analyzed to meet new seismic requirements. Results show that the response spectrum obtained in original seismic test at different positions of the main control console can envelop that in seismic response analysis, indicating that the integrity of the console structure determined by the analysis method could be maintained during the seismic test performed under new requirements.
    • Automatic Control
  • Automatic Control
    Early Fault Warning of Coal Mills Based on Echo State Network
    Zhang Jin
    2021, 35(1): 53-57,62. https://doi.org/10.19806/j.cnki.fdsb.2021.01.011
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    To achieve early fault warning of interrupted coal supply from coal mills in a thermal power unit, a fault warning method was proposed based on echo state network (ESN), which was compared with traditional static threshold method, combined with actual operation data of the unit. Simulation results show that the fault warning signals based on ESN can be given in ahead of actual interrupted signals, thus achieving early fault warning of coal mills.
  • Automatic Control
    Fault Diagnosis Method for Thermal Processes Based on DSPCA
    Jing Yajie, Dong Honglin, Wei Zhikang, Yang Xu
    2021, 35(1): 58-62. https://doi.org/10.19806/j.cnki.fdsb.2021.01.012
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    To solve the problems of insufficient sensitivity of principal component analysis (PCA) and sparse principal component analysis (SPCA) in detecting dynamic data as well as the excessive noise produced by dynamic principal component analysis (DPCA), a new fault diagnosis method for thermal processes, namely dynamic sparse principal component analysis (DSPCA), was proposed. Fault detections were conducted by PCA, DPCA, SPCA and DSPCA, with DSPCA applied to the fault detection of high-pressure heaters. Results show that the DSPCA method has higher detection accuracy, with strong fault sensitivity to the data of thermal processes, especially to the pipeline leakage fault of high-pressure heaters, which therefore is suitable for real-time fault detection of industrial processes.
    • Operation & Retrofit
  • Operation & Retrofit
    Control Optimization for NOx Emission from Co-firing of High-sulfur Coal
    Duan Bao, Fan Long
    2021, 35(1): 63-67. https://doi.org/10.19806/j.cnki.fdsb.2021.01.013
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    To reduce the NOx emission from co-firing of high-sulfur coal in a 350 MW supercritical boiler, corresponding measures were proposed considering the actual operation conditions, such as the ammonia injection for combustion adjustment optimization, the automatic strategy for dynamic deviation control optimization, and so on. Results show that via the method proposed, good control effects can be obtained for NOx emission from co-firing of high-sulfur coal, which may serve as a reference for similar units.
  • Operation & Retrofit
    Analysis and Treatment on the Deformation of Steam Turbine Cylinders in a 9F Gas-Steam Combined Cycle Unit
    Liu Ming, Dong Guangming, Zhu Weixiong, Xie Xin
    2021, 35(1): 68-71. https://doi.org/10.19806/j.cnki.fdsb.2021.01.014
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    Aiming at the deformation faults existing in the high and medium pressure cylinder during the overhaul of a 9F gas-steam combined cycle unit, an analysis was conducted on the calculation results for the high-pressure main steam pipe and reheat steam pipe under normal design condition and valve overhaul condition, after which, corresponding countermeasures were proposed. Results show that the serious deformation faults existing in the high and medium pressure cylinder are found to be caused by the increase of thrust/moment at the interface of the lower cylinder during valve overhaul. The problem can be solved by adopting a fixed structure in the process of overhaul.
  • Operation & Retrofit
    Failure Analysis and Improvement of a Chemical Sampling Pipe Socket in an Ultra-supercritical Boiler
    Liao Weihui, Yuan Panfeng
    2021, 35(1): 72-74. https://doi.org/10.19806/j.cnki.fdsb.2021.01.015
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    To solve the problem of steam leakage resulting from the failure existing in a chemical sampling pipe socket for an ultra-supercritical boiler, force analysis was conducted on the pipe socket by numerical simulation to find the failure causes through hardness measurement, material test and fracture surface analysis, after which, the structure of the pipe socket was improved. Results show that the failure of the pipe socket is found to be caused by the incomplete penetration and superimposed stress existing in the weld seams, and the problem is finally solved through structure improvement of the socket.