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    Fundamental Research
  • Fundamental Research
    Effect of Post Treatment Process on Microstructure and Mechanical Behaviour of Hastelloy-X Alloy Produced by Selective Laser Melting
    HE Lei, WANG Chao, DENG Tiantian
    2023, 43(5): 511-518. https://doi.org/10.19805/j.cnki.jcspe.2023.05.001
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    Hastelloy-X alloy manufactured by selective laser melting was treated by heat treatment and hot isostatic pressing process, so as to study the microstructure, high-temperature tensile properties and low cycle fatigue properties under different post treatment processes, and the fatigue failure mechanism was analyzed. Results show that there are many defects such as unmelted powder, pores and microcracks in as-deposited Hastelloy-X samples. These defects have no obvious improvement after heat treatment, which can be eliminated after hot isostatic pressing, and the relative porosity of Hastelloy-X alloy is increased to 99.9%. The ultimate tensile strength and elongation at 815 ℃ have a certain improvement after heat treatment. And the ultimate tensile strength of HIP-processed specimen is decreased, but the elongation is increased. The fatigue life of HT-processed specimen is half of HIP-processed. The location of unmelted powder, inclusion and other defects in Hastelloy-X alloy is the main sites for the fatigue crack source. The HIP process can eliminate the inner defects in Hastelloy-X alloy and improve fatigue life greatly.
  • Fundamental Research
    Analysis of Notch Effect and Damage Assessment Criteria of 316H Stainless Steel Under Creep-Fatigue Loading
    GONG Weizhong, TAN Jianping, ZENG Xin, ZHANG Liping, SHAO Xuejiao, SU Dongchuan, LIU Changjun
    2023, 43(5): 519-525. https://doi.org/10.19805/j.cnki.jcspe.2023.05.002
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    Influence of load level, holding time, and notch size on the creep-fatigue life of 316H stainless steel at 600 °C and the notch effect were studied when the creep-fatigue tests of 316H stainless smooth bar and notched bar with different V-shapes under the controlled load were performed. The feasibility of the application of creep-fatigue assessment criteria in ASME BPVC III-NH to 316H notched bar specimens was assessed. Results show that the creep-fatigue life of 316H stainless steel exhibits notch weakening effect under short-term and notch strengthening effect under long-term loading, respectively. With the increase of holding time, more pits and bumps occur in the crack propagation area of the fracture, and the dimples in the instantaneous fracture zone become larger and deeper. According to the current experimental resluts, the creep-fatigue assessment criterion in the ASME code is suitable for assessing the notched components of 316 stainless steel.
    • Power Equipment and System
  • Power Equipment and System
    Analysis on the Steam Temperature Deviation of the Vertical Water Wall and the Adjustment Plan of the Throttle Ring for an Ultra-supercritical Boiler
    YANG Haoyu, ZHANG Xirong, LI Weiteng, YANG Dong, WANG Yongjie, SONG Baojun, XIA Liangwei
    2023, 43(5): 526-534. https://doi.org/10.19805/j.cnki.jcspe.2023.05.003
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    Experimental research and hydrodynamic calculation were carried out to solve the problems of deviation in steam temperature, large temperature fluctuation and the transverse cracks in the lower furnace water wall of a 660 MW ultra-supercritical boiler. According to the boiler design scheme, a hydrodynamic calculation mathematical model for the boiler flow network system was established, and the temperature test points were arranged on the water wall. Based on the actual furnace measurement data of the steam temperature, the heat load and thermal deviation distribution in the unit 1 furnace at 270 MW load was calculated. Then the arrangement of the throttle ring was adjusted, and the adjusted hydrodynamic and flow instability was calculated. Results show that the outlet steam temperature is more uniform and the adjustment can prevent steam temperature fluctuation without pulsation. At the same time, the steam temperature distribution of the lower furnace water wall at medium and high loads is more uniform after the throttle ring adjustment, and the temperature deviation is significantly improved.
  • Power Equipment and System
    Analytical and Experimental Research on Tribological Properties of Water-lubricated Thrust Bearings
    JIA Qian, YANG Shuai, LIU Zhe, LI Sihan, CAI Long, HAN Haiyan, YAN Feifei, YUAN Xiaoyang
    2023, 43(5): 535-542. https://doi.org/10.19805/j.cnki.jcspe.2023.05.004
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    According to the characteristics of extreme working conditions and long service life of the water-lubricated thrust bearing in the main pump of a nuclear power plant unit, the tribology research was carried out from two aspects of analysis and experiment. In terms of analytics, considering the lubrication performance analysis under balanced support, the minimum lubrication film thickness (hmin), friction torque (Mf) and temperature rise (ΔT) of thrust bearing at different rotational speeds were simulated and analyzed, and the bearing wear prediction model based on the numbers of start and stop was established according to the take-off speed. In terms of test, the friction and wear tests related to bearing materials were carried out, and the friction coefficient (f) and volume wear (ΔW) of graphite-stainless steel friction pair under the conditions of boundary lubrication and dry friction were obtained. The lubrication film thickness (h), temperature on the tile surface (T) and wear mass (Δm) of graphite bearing were tested by scaled bench test. Results show that the working speed has a greater impact on hmin and a smaller impact on ΔT. The graphite material has a greater impact on f and ΔW under the condition of dry friction. From the perspective of h and T, the test results are close to the theoretical calculation results, indicating that the semi-scale scaling test has a better similarity with the actual working conditions.
  • Power Equipment and System
    Economic Analysis of the Coordinated Frequency Regulation for Energy Storage and Gas Turbine System
    QIAN Wenhan, LIU Pei, XUE Yali, LI Zheng
    2023, 43(5): 543-549. https://doi.org/10.19805/j.cnki.jcspe.2023.05.005
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    To study the economic feasibility of coordinated frequency regulation for a system combined energy storage battery with gas turbine, an operation strategy was proposed, in which the gas turbine was responsible for low frequency component of frequency demand signal, while the energy storage battery compensated for its power output, and the state of the battery charge was considered. A dynamic model of heavy-duty gas turbine was established based on Matlab/Simulink platform, and an economic evaluation model for the system was constructed. Under a period of actual frequency regulation demand signal, the total system costs of single energy storage system and combined system of energy storage and gas turbine were compared when they achieve the same frequency regulation performance. Results show that the energy storage battery capacity required for frequency regulation of combined system is reduced, which leads to a decrease in the system total costs. The combined system thus becomes a more economically competitive frequency regulation resource.
  • Power Equipment and System
    Experimental Study on Slagging and Fouling Characteristics During Combustion in the Slag-tap Vertical Cyclone Boiler
    ZHANG Sizhuo, YUAN Yichao, ZHANG Xiang, YAN Kai
    2023, 43(5): 550-557. https://doi.org/10.19805/j.cnki.jcspe.2023.05.006
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    In order to realize the efficient and clean utilization of slagging coal with the slag-tap boiler, it is necessary to accurately master the thermal calculation method for the slag-tap boiler and its slagging and fouling characteristics of heat transfer surfaces. Based on the hot-state experimental results for a 75 t/h slag-tap vertical cyclone boiler under different operating conditions and the thermal calculation method of the slag-tap boiler with double furnaces in the 1973 edition of the standard of thermal calculation for boiler utilities of USSR(1973 Ed. of USSR), the slagging and fouling characteristics of heat transfer surfaces of the slag-tap vertical cyclone boiler were studied. The fouling characteristics of superheaters, economizers and air heaters in the slag-tap vertical cyclone boiler were obtained. Results show that method ВТИ in 1973 Ed. of USSR is more consistent with the performance of the furnaces in the slag-tap boiler with double furnaces than method ЦКТИ. The modification coefficients of thermal effectiveness factor of high and low temperature superheater are 1.19~1.25 and 0.63~0.67 respectively. The coefficients increase with the increase of the boiler load. The modification coefficients of fouling factor of high and low temperature economizer are 5.00~5.80 and 6.00~6.90 respectively. The coefficients decrease with the increase of the boiler load. The modification coefficients of utilization factor of high and low temperature air heater are 0.53~0.56 and 0.80~0.85 respectively. The coefficients increase with the increase of the boiler load.
  • Power Equipment and System
    Influence of Diffuser Angle on Hydraulic Performance of Reactor Coolant Pump
    YE Daoxing, LUO Yimin, LIU Anlin, CHEN Junlin, WU Jinchen, ZHAI Fengli, LAI Xide
    2023, 43(5): 558-567. https://doi.org/10.19805/j.cnki.jcspe.2023.05.007
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    In order to study the influence of diffuser angle on hydraulic performance of the reactor coolant pump, the steady numerical calculation was carried out at 5 reactor coolant pump models with different diffuser angles, and the flow resistance in the pump was analyzed based on entropy production theory. Results show that the head and efficiency of the DY4 model are the highest under the design flow condition and large flow condition, and the optimal efficiency appears at the design flow condition, which is 3.68% higher than that of the DY1 model. Under the design flow condition and large flow condition, the pressure and velocity streamlines of the DY4 model distribute uniformly and change smoothly. The fraction of the diffuser and volute flow resistance is the lowest, and high pressure loss area is small. Under the condition of small flow rate, the head and efficiency of the DY5 model are the highest, and the highest efficiency appears at the flow ratio of 0.8. The static pressure in the guide vanes and volute of the DY5 model is significantly higher than other models, the velocity changes uniformly in the flow channel, and the flow resistance in the diffuser and volute are both the lowest.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Investigation and Application of Thermal Design of Large-scale Wind Turbines Based on CFD Numerical Simulation
    MA Pengnan, WANG Gaozhan, DUAN Heping, JIANG Tingting, LUO Yongshui
    2023, 43(5): 568-574. https://doi.org/10.19805/j.cnki.jcspe.2023.05.008
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    CFD numerical simulation technology was applied to the thermal design of wind turbines. Firstly, the reliability of the simulation method was verified by the comparative analysis of the simulation results of the heat flow field and the measured data of the wind turbines. On this basis, the problems of whether the axial fan and the shutters at the rear of the wind turbine can be cancelled and the clogging of the filter cotton of the tower door shutters were studied. Results show that the air flow of the shutters at the rear of the nacelle has very little influence on the temperature field in the nacelle. Therefore, the axial fan and shutters at the rear of the nacelle can be removed. When the filter cotton of the tower door shutters is completely blocked, there is a risk of over-temperature of the converter platform and the air inlet of the converter under high-temperature weather conditions. It is necessary to clean the filter cotton regularly to increase the air flow.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Optimized Decomposition of AGC Load Command for Comprehensive Utilization of Energy Storage in the Thermal Power Unit
    ZHAO Zheng, SUN Heyu, CHEN Jiangli
    2023, 43(5): 575-581. https://doi.org/10.19805/j.cnki.jcspe.2023.05.009
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    As it is difficult to increase the variable load rate of a thermal power unit using single energy storage, the comprehensive utilization of two types of rapid load change such as condensate throttling regulation and coolant throttling regulation was used to improve its rapid load change. The power increment range and duration of condensate throttling regulation and power increment range of coolant throttling regulation were determined. With the premise of safe unit operation, the improvement of traditional AGC load command decomposition was performed, and the decomposed load command was optimized. Results show that the designed system has a good load change effect with the premise of safe unit operation, which improves its overall load change speed and realizes the reasonable and efficient utilization between different types of energy storage in the thermal power unit.
  • Digitalization and Intelligentization
    Research on IT2TSK Fuzzy Modeling Method for Digital Twin
    ZHANG Yue, GAO Xiaona, WANG Mengxue, LIAN Youkun
    2023, 43(5): 582-589. https://doi.org/10.19805/j.cnki.jcspe.2023.05.010
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    In order to improve the accuracy of thermal power unit dynamic process model under variable power conditions to meet the requirements of digital twin model, a series structure hybrid model was constructed. Quantum particle swarm optimization (QPSO) algorithm was used to build global model and interval type-2 T-S fuzzy model (IT2TSK) was introduced to realize the precise evolution of the twin sub-model and the transition process. Aiming at the problem that the fuzzy sets and fuzzy rules are difficult to determine in IT2TSK model, a two-step iterative method was designed to determine the parameters of the front and rear parts, so as to ensure that the parameters of fuzzy set can reflect the uncertainty between different state sets vertically, and the fuzzy rules can realize the smooth transition between sub-models horizontally, which ensured that digital twin body model is highly approximate to the dynamic process under all working conditions. Results show that taking the air preheater as an example, the output of parameter online adaptive hybrid model based on IT2TSK fuzzy model can track the actual value more accurately and the overall precision is higher on the variable power training set, compared with the simplified fixed condition model and type-1 T-S fuzzy model.
  • Digitalization and Intelligentization
    Research on Covert Attack Method of Deaerator Water Level Control System in Nuclear Power Plants Based on LSTM
    WANG Dongfeng, DENG Jianyong, HUANG Yu, GAO Peng
    2023, 43(5): 590-597. https://doi.org/10.19805/j.cnki.jcspe.2023.05.011
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    Aiming at the problem that realizing covert attack of deaerator water level control system in nuclear power plants would have a high-precision estimation model of the attacked objects, a covert attack method based on long-short term memory (LSTM) neural network was proposed. In this method, output and input signals of feedback controllers obtained from deaerator water level control system in nuclear power plants were utilized for the data set of LSTM, and a high-precision estimation model was obtained through training. This estimation model was used to design a covert attacker to impose attack signals on an attacked object, so as to realize covert attack. Finally, the effectiveness and concealment of the proposed method were verified by simulation experiments. Results show that the method has a certain influence on deaerator water level in nuclear power plants and higher concealment.
  • Digitalization and Intelligentization
    Fault Warning of Pulverizing System Based on Deep Bidirectional Gated Recurrent Neural Network
    ZHAO Zheng, DING Jianping
    2023, 43(5): 598-605. https://doi.org/10.19805/j.cnki.jcspe.2023.05.012
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    In order to construct an estimation model with strong robust, combined with the idea of stacked auto-encoders, a state estimation and fault warning method for the pulverizing system based on deep bidirectional gated recurrent neural network was proposed. First, the historical data of the normal operation state variables of the pulverizing system was selected as training input of the deep bidirectional gated recurrent neural network, and the normal state estimation model of the pulverizing system was establish based on powerful feature learning ability of the network. The sliding window method was used to construct the state monitoring index of the pulverizing system, and the indicator threshold was determined, so that the simulation was carried out by historical operating data of the pulverizing system in coal-fired power plants. Results show that comparing with other methods, the deep bidirectional gated recurrent neural network model has better estimation performance, which can send out early warning information in time before faults occur, to achieve the purpose of the early fault diagnosis.
  • Digitalization and Intelligentization
    Dynamics Research on Fault of Multistage Gear Transmission System for Wind Turbine
    YANG Xin, XIANG Ling, ZHANG Xingyu, ZHU Haowei, AN Chaohui
    2023, 43(5): 606-613. https://doi.org/10.19805/j.cnki.jcspe.2023.05.013
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    Considering the factors such as sun gear support,time-varying mesh stiffness and comprehensive mesh error, etc., a translational-torsional nonlinear dynamic model of wind turbine gearboxes with sun gear root crack was established, and the influence of sun gear crack fault and its evolution on the system dynamic response was analyzed. Results show that sun gear cracks would affect the meshing stiffness of the gear tooth, thereby affecting the dynamic response of the system. Gear cracks cause significant periodic shocks on the time-domain waveform of the system. The motions of the system in the bifurcation diagram develop from single period to multi period. The frequency spectrum has the fault characteristic frequency and its harmonic frequency, and there are many side frequency components near the mesh frequency. As the degree of cracking deepens, the time-domain characteristics become more complex, meanwhile, the identifiability of fault feature frequencies in the frequency spectrum has been enhanced.
  • Digitalization and Intelligentization
    Fault Diagnosis of Induced Draft Fan Bearing Based on LSTM and Evidence Theory
    TIAN Liang, YUAN Cunbo
    2023, 43(5): 614-621. https://doi.org/10.19805/j.cnki.jcspe.2023.05.014
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    As an important auxiliary equipment of the boiler, the abnormal vibration of the bearing of induced draft fan would cause great losses to the power plant, but the internal structure of induced draft fan is complex, so it is difficult to build an accurate mechanism model for fault diagnosis. To solve this problem, a method of data-driven fault diagnosis was proposed. In this method, the state of induced draft fan bearing was diagnosed through the prediction ability of long-short term memory (LSTM) and the multi-source information fusion ability of evidence theory. Then LSTM neural network was used to predict the denoised data, and the root mean square error (RMSE) between the predicted value and the denoised data was calculated. Finally, the improved evidence theory was used to fuse the RMSE of different parameters and diagnose the fault. Results show that this method can predict the abnormal vibration of the induced draft fan bearing about 350 s in advance, accurately diagnose the vibration state of the induced draft fan bearing, and effectively improve the problem of data conflict.
  • Digitalization and Intelligentization
    High-resolution Reconstruction of Temperature Field Based on DenseNet and Acoustic Tomography
    ZHANG Lifeng, LI Jing
    2023, 43(5): 622-630. https://doi.org/10.19805/j.cnki.jcspe.2023.05.015
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    A two-stage high-resolution reconstruction algorithm of acoustic tomography temperature field based on virtual observation combined with densely connected network (DenseNet) was proposed. Aiming at the total least squares, the ultrasonic time-of-flight (TOF) was reconstructed by virtual observation method to obtain the temperature distribution under the coarse grid. Then, DenseNet was built to predict the temperature distribution under the refined grid. Numerical simulation on typical temperature field model was carried out using dual-input model and the modular output method. Results show that the reconstruction quality and noise resistance of the algorithm are superior to commonly used methods, such as virtual observation method, Landweber iteration method, Tikhonov algorithm and algebraic reconstruction technique (ART) method.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Thermo-Environmental Characteristics Analysis of Municipal Solid Waste Power Generation System
    PANG Yue, FANG Haonan, Lü Xiaojing, WENG Yiwu
    2023, 43(5): 631-640. https://doi.org/10.19805/j.cnki.jcspe.2023.05.016
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    Based on the established thermodynamic model of municipal solid waste (MSW) power generation system, effects of MSW composition and flow rate on the thermal efficiency and pollutants emission were studied, and their impact on the thermo-environmental characteristics was evaluated. Results show that the carbon content in MSW components dominates the thermal efficiency of MSW power generation. The maximum energy-ecological efficiency (ε efficiency) of 0.61 is achieved in November with the highest monthly carbon content of 30.23% in MSW, and the thermal efficiency and total equivalent pollutants emission of the power generation system are 30.24% and 20.7 kt, respectively. Moreover, the monthly change of MSW composition causes the maximum variation of ε efficiency by 3.60%. When the MSW flow rate decreases from 28.53 kg/s to 14.27 kg/s, the thermal efficiency and total equivalent pollutants emission reduce from 28.53% to 26.90% and from 19.07 kt to 9.54 kt, respectively, which results in the reduction of ε efficiency from 0.59 to 0.53. As MSW flow rate decreases by 10%, the maximum reduction of ε efficiency by 1.8% is observed. MSW composition has a greater impact on ε efficiency than its flow rate. Additionally, the reduction of NOx, PM and SO2 emission in engineering practice can increase the ε efficiency. NOx has the most significant effect on the ε efficiency, which increases from 0.605 to 0.667 with an increment of 10.25%.
  • Green Energy and Low-carbon Technology
    Analysis of Current Governance and Treatment Techniques for VOCs
    SUN Dou, WANG Yungang, DAI Yanjun, ZHAO Qinxin, LIANG Zhiyuan, SHAO Huaishuang
    2023, 43(5): 641-654. https://doi.org/10.19805/j.cnki.jcspe.2023.05.017
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    Volatile organic compounds (VOCs) are important precursors for the formation of O3 and PM2.5, which is extremely harmful to human health and environment. VOCs governance becomes the key to air pollution control. Based on the current situation of VOCs treatment, the sources and types of VOCs were summarized, and the policies, regulations and standards related to VOCs in China were sorted out. In addition, the VOCs treatment technologies were expounded in detail. The research status of adsorption, catalytic combustion and adsorption-catalytic combustion combined treatment technology was emphatically analyzed and the future development direction of VOCs treatment was prospected.
    • Integrated Energy System
  • Integrated Energy System
    Distributed Cooperative State Estimation Method of Electric-Heat Integrated Energy System Based on Multiple Time Sections
    LI Taotao, ZHOU Dengji, MA Shixi, HUANG Di
    2023, 43(5): 655-662. https://doi.org/10.19805/j.cnki.jcspe.2023.05.018
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    A state estimation method based on multiple time sections for the electric-heat integrated energy system was proposed. The influence of heat transmission time delay characteristics on the current estimated time was considered. The measurement data on the grid side and the heating network side were used to comprehensively estimate the state of the system. Additionally, the distributed cooperative solution method was applied to establish a state estimation solution framework. According to the coupling characteristics of subsystems, the boundary constraints were implemented on the estimated data of each network side to improve the accuracy of the results and complete the passage of time window. Results show that the state estimation method based on multiple time sections can more accurately track the real-time operating state of the monitoring system in a small time scale, and the estimation ability is maintained at a relatively stable level. Additionally, it has a positive significance to reduce the calculation errors and improve the solving efficiency.