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    Fundamental Research
  • Fundamental Research
    Study on the Structure and Properties of the Gas-Nitrided Layer of SP-700 Titanium Alloy for the Last Stage Blade of Steam Turbine
    LI Cong, NIE Bingyue, REN Yanjie, LI Wei, CHEN Wei, ZHOU Libo, CHEN Jian
    2024, 44(8): 1153-1162. https://doi.org/10.19805/j.cnki.jcspe.2024.230404
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    Vacuum gas nitriding process was applied to strengthen the surface of the SP-700 titanium alloy at different temperatures. The surface morphology, cross-sectional morphology, hardness, abrasion resistance and electrochemical corrosion performance of the newly formed gas-nitrided layers were investigated using scanning electron microscope (SEM), optical microscope (OM), micro-Vickers hardness tester, reciprocating friction and warm damage tester, white light interference three-dimensional surface profiler and electrochemical workstation, respectively. The corrosion behavior of the gas-nitrided layers was determined by immersion corrosion method in HF solution. Results show that, the microstructural morphologies of the gas-nitrided layers are significantly influenced by the processing temperatures. With the increase of temperature, the amount of nitride increases and the nitride layer becomes denser. The hardness of the high-temperature gas-nitrided layer was about 1.9 times higher than that of the matrix, and the relative abrasion resistance can reach 51.34. All samples can be passivated spontaneously in 3.5% NaCl solution, indicating their good electrochemical corrosion resistance. The samples with gas-nitrided layer perform better in HF corrosion solution, and the higher the processing temperature, the better the corrosion resistance of the samples.
    • Power Equipment and System
  • Power Equipment and System
    Experimental Study on Combustion Characteristics of a W-shaped Flame Boiler Under Acoustic Wave Excitation
    YANG Yanfeng, LIANG Jianguo, HAN Feng, XUE Xiaoliang, YANG Yang, LI Xinzhuo
    2024, 44(8): 1163-1172. https://doi.org/10.19805/j.cnki.jcspe.2024.230407
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    To explore the application potential of sound-assisted combustion technology in W-shaped flame boilers, the combustion characteristics of a W-shaped flame boiler with real-time load of 315 MW under acoustic excitation were experimentally studied. Twelve and four acoustic excitation devices were staggered in the main combustion area and the burning area of the boiler, respectively, and they were put into operation in a group of three devices in a circular manner. The frequency of the motor driving the acoustic excitation device was 35 Hz, and the corresponding intake pressure was maintained at 0.35-0.47 MPa. In the test, the changes of the NOx mass concentration at the inlet of the A and B sides of the denitration tower, the SOx mass concentration at the inlet of the desulfurization unit, and the coal consumption of the unit were recorded through the distributed control system (DCS) of the centralized control room of the power plant. Results showed that, after the acoustic excitation was put into the denitrification tower, the mass concentration of NOx at the inlet of the A and B sides of the denitration tower is decreased by 6.08% and 5.47%, respectively, the SOx mass concentration is decreased by 1.24%, and the average coal consumption of the unit is decreased by 1.5 g/(kW·h). In addition, based on the ash sampling analysis of the economizer and air preheater outlet, it is found that the carbon mass fraction of fly ash is decreased by 1.64% and 1.70% respectively, compared with the case without acoustic excitation. Sound-assisted combustion technology can effectively improve the thermal efficiency of W-shaped flame boilers and reduce pollutant emissions.
  • Power Equipment and System
    Optimization of Outlet Shape of Film Cooling Hole Based on Bezier Curve
    LIU Rui, WEN Shencheng, ZHANG Chuanliang
    2024, 44(8): 1173-1180. https://doi.org/10.19805/j.cnki.jcspe.2024.230388
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    Based on Bezier curve, a parameterized configuration method for outlet shape of film cooling hole was proposed. Outlet shape of film cooling hole could be changed by adjusting control points of Bezier curve. Latin hypercube sampling (LHS) and numerical simulation methods were used to obtain a large number of film cooling effects with different outlet shape of film cooling hole. Radial basis function neural network (RBF-NN) prediction model and genetic algorithm (GA) were used to optimize outlet shape of film cooling hole. Results show that the optimized cooling holes can effectively inhibit strength and size of counter-rotating vortex pair (CVP), and reduce the mixing loss between cooling flow and hot main stream; at the same time, the optimized outlet shape of film cooling hole has an expansive channel, which weakens upward momentum of cooling flow at the outlet of film cooling hole, effectively inhibits penetration of cooling flow to hot main stream, and enhances film cooling efficiency. Under the blowing ratio (M) of 0.91, the film cooling efficiency of the optimized film cooling hole is improved by 40.48% and 17.82%, respectively, compared to that of circular hole and fan-shaped hole.
  • Power Equipment and System
    Aerodynamic Design and Performance Optimization Study of a Radial-inflow Turbine with Organic Working Medium
    LU Xuxiang, SONG Zeng, LIU Rui, DING Haixia, LI Yixuan
    2024, 44(8): 1181-1188. https://doi.org/10.19805/j.cnki.jcspe.2024.230443
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    In order to improve the efficiency and performance of radial-inflow turbines with organic working medium, one-dimensional aerodynamic design for 400 kW radial-inflow turbine with organic working medium was carried out.Radial-inflow turbine was modeled based on one-dimensional design results,and its performance under designed working conditions was predicted by combining with three-dimensional numerical simulation.Taking isentropic entropy efficiency of radial-inflow turbine as the target,the meridional flow path of impeller was optimized and designed by uniform test method.Results show that the optimized radial-inflow turbine has a more distinct pressure distribution hierarchy than that of the original one,and overall entropy increment, generating friction loss and trailing loss are obviously reduced.Work capacity of the blades increases,and flow inside radial-inflow turbine is improved. Isentropic efficiency of the optimized radial-inflow turbine is increased from 82.33% to 85.92%,and output power is increased by 18.04 kW.
  • Power Equipment and System
    Research on Feature Classification and Deterioration Analysis Algorithm of Medium-speed Coal Mills
    ZHANG Yuandong
    2024, 44(8): 1189-1195. https://doi.org/10.19805/j.cnki.jcspe.2024.230384
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    To address issues of local sensitive hash in the feature classification process of the Simhash algorithm and the low accuracy of deterioration analysis algorithm for medium-speed coal mills, a feature classification and deterioration analysis algorithm of medium-speed coal mills was proposed. Firstly, a feature classification method was designed based on the Simhash mechanism combined with cosine theorem and matrix similarity. Then, the judgment rules for the deterioration analysis of medium-speed coal mills were designed based on the eight-neighborhood mechanism and the adaptive thresholds. Results show that the identification degree of characteristic parameters, the fault correlation and the health state prediction accuracy of medium-speed coal mills are improved significantly. Compared with the current mainstream machine learning algorithms, the calculation efficiency is enhanced significantly when the RMSE loss is small, and the accuracy and robustness of the proposed algorithm are higher.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Research on Yaw Error Algorithm of Wind Turbine Based on Actual Power Curve Threshold Screening
    LÜ Songhao, LIU Xiangmin, FANG Chao, DING Shifa, YU Congji, MA Yongxin
    2024, 44(8): 1196-1204. https://doi.org/10.19805/j.cnki.jcspe.2024.230428
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    Existing methods for evaluating yaw error of wind turbine often rely on lidar or long-term (more than three months) operating data. A yaw error algorithm based on actual power curve threshold screening was proposed for calculation of short-term operating data yaw error before the first maintenance of new units. Firstly, the Bin method was used to solve the actual power curve of unit, and the threshold method of the actual power curve was used to eliminate data that may reduce calculation accuracy with no need for nacelle transfer function (NTF). Then, the selected dataset was divided into wind speed compartments, and interval mean method was used to solve the representative yaw error of each wind compartment. Finally, wind speed weighting method was used to solve the yaw error. Through practical application in an onshore wind farm in Jiangsu, it shows that the proposed algorithm can obtain effective yaw error calculation results for both short-term and long-term operating data.
  • New Energy Resources and Energy Storage
    Performance Analysis of an Integrated Solar Power Generation and Storage System Based on the S-CO2 Brayton Cycle
    ZHANG Xuelei, LIANG Jianxiong, WANG Pu, ZHAO Zhe, JIA Chengguang
    2024, 44(8): 1205-1215. https://doi.org/10.19805/j.cnki.jcspe.2024.230406
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    This paper proposed an integrated system which includes a tower-type solar thermal power system and energy storage system, employing S-CO2 and quartz as the storage media and a re-compressed S-CO2 Brayton cycle as the power cycle. Based on the Gensystem platform, mathematical models of the power cycle, solar heat collection system, and S-CO2 thermocline storage tank were developed to investigate the performance of the heat collection system and the dynamic characteristics of heat storage and release in the S-CO2 thermocline storage tank. This foundation facilitated an analysis of the integrated system's thermodynamic and economic performance. Results show that after 13 cycles of heat storage and release, the temperature at the outlet of the thermocline storage tank tends to be stable. At the conclusion of heat release, the temperature of the thermal fluid exiting the tank is decreased by 63 K, while at the end of heat storage, the temperature of the cold fluid exiting is increased by 46 K. Compared with a dual storage tank tower solar thermal power system, the average daily power generation efficiency on the summer solstice and winter solstice is enhanced by 1.8% and 1.7%, respectively. The total system investment is reduced by 9.46%, the levelized cost of electricity is reduced by 9.45%, and the investment payback period is shortened by 1.8 years.
  • New Energy Resources and Energy Storage
    Thermodynamic Analysis of a Photovoltaic/Photothermal Integrated Power Generation System Based on Solar Energy Spectrum Utilization
    ZHANG Manzheng, GUO Wei, FANG Yucheng, ZHANG Jiawei, WU Xiangfeng, YUE Quan, MIAO Zheng
    2024, 44(8): 1216-1225. https://doi.org/10.19805/j.cnki.jcspe.2024.230392
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    By dividing the incident solar spectrum into bands, an integrated photovoltaic (PV) and photothermal (PT) driven organic Rankine cycle (ORC) was established. Thermodynamic analysis of the system was conducted under the temperature limit of 100 ℃ for the cooling panel, to identify suitable working fluids for the ORC system and optimize the evaporation temperature. Results show that isobutene as the cooling fluid for the photovoltaic system and the working fluid for the ORC system, the highest system efficiency can be achieved. Frequency division technology transfers the heat dissipation load of the cooling panel to the collector, which can reduce the cooling demand of the photovoltaic panel and thus reduce the mass flow rate of the working fluid. It has a positive effect on improving the system's power generation capacity, and can enhance the efficiency of pure photovoltaic electricity generation by 9%. Additionally, frequency division efficiency and the absorption band of solar cells significantly impact the overall efficiency of the integrated power supply system.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    MPPT Strategy of Photovoltaic System Based on Auto-coupling PI Control
    YU Leyan, ZENG Zhezhao, ZHANG Changqi
    2024, 44(8): 1226-1233. https://doi.org/10.19805/j.cnki.jcspe.2024.230363
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    In order to solve the problems of slow response speed, noticeable chattering and low steady-state accuracy when the external environment changes in the maximum power point tracking (MPPT) method of photovoltaic system, the auto-coupling PI control strategy based on auto-coupling PID(ACPID) control was proposed. Based on the photovoltaic system of Boost circuit, it simplified the controlled system with coordinate transformations. At the same time, the strategy introduced virtual control volumes to divide the system into outer loop voltage control and inner loop current control, and it defined internal dynamic and external disturbances as total disturbance, which equivalently mapped the photovoltaic power generation system as a linear perturbation system. And the auto-coupling PI controllers of outer loop and inner loop were designed based on the auto-coupling PI control system. Results show that the proposed method can realize the effective MPPT control of the photovoltaic system and has the faster response speed, good anti-chattering ability and good robustness to external environmental changes.
  • Digitalization and Intelligentization
    Clustered Optimization Control of Wind Farm Yaw Angle Based on Wake Determination
    CAI Wei, HU Yang, LIU Jizhen
    2024, 44(8): 1234-1243. https://doi.org/10.19805/j.cnki.jcspe.2024.230414
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    In order to optimize the overall power output and fatigue load of the wind farm, an optimization method of wind turbine yaw angle group was proposed. A neural network judgment model for wind turbine wake interference was established, and the relative coordinates of the wind turbine and the incoming wind speed were taken as characteristic values, to determine whether there was wake interference between the fans. The connected component decomposition algorithm was introduced to divide the wind farm into multiple aerodynamic decoupling groups without wake interference. With the goal of increasing power and suppressing load, the improved adaptive evaluation particle swarm algorithm was used to optimize all swarms in parallel. Results show that compared with the greedy algorithm and the overall optimization method, the group optimization method has better effects on power improvement and load suppression, and its stability is better.
  • Digitalization and Intelligentization
    Parameter Optimization Control of RBF Conditional Integral Sliding Mode for SCR Denitration System
    HUANG Yu, WEI Jiaxuan, ZHANG Xiong, YI Heng, WANG Xiaoyan
    2024, 44(8): 1244-1252. https://doi.org/10.19805/j.cnki.jcspe.2024.230166
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    To address the issue that the selective catalytic reduction (SCR) denitration system is difficult to control due to the change of system characteristics along with power load under deep peak regulation of thermal power units, an optimization control scheme of conditional integral sliding mode based on radial basis function (RBF) was proposed. The conditional integration sliding mode was used to reduce the jitter and adjustment time, and the RBF was used to approximate the unknown disturbance under the change of the characteristics of the SCR denitration system in real time to improve the robustness of the system. A Nash equilibrium quantum particle swarm optimization (NEQPSO) algorithm was proposed to obtain the optimal parameters of the RBF conditional integral sliding mode control scheme, and the simulation experiments were carried out under the load of 20%-100%. Results show that compared with the traditional control scheme, the optimized RBF conditional integral sliding mode control reduces the overshoot by 50.26%, the adjustment time is shortened by 13.55%, and the overshoot is only 1.50% under the interference signal, which has faster response speed, stronger anti-interference ability and better robustness.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Performance Analysis of a Power Generation System with Pre-combustion CO2 Capture Based on Staged Coal Gasification
    LI Jichao, HAN Wei, MA Wenjing, YE Yiyin, JIN Hongguang
    2024, 44(8): 1253-1263. https://doi.org/10.19805/j.cnki.jcspe.2024.230498
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    A power generation system with pre-combustion CO2 capture based on staged coal gasification and chemical recuperation was proposed to achieve high-efficiency and low-carbon power generation from coal. The system decoupled the coal gasification process into two stages: a pyrolysis stage at 600 ℃ and a gasification stage producing syngas at 1 400 ℃. The exhaust heat from gas turbines was used to drive pyrolysis, and in addition, the sensible heat of syngas was used to drive pyrolysis gas reforming. The thermodynamic performance of the present system was compared with the reference system, and the effect of different key parameters on the system performance was analyzed. Results show that at the carbon capture ratio of 90%, the net power generation efficiency, exergy efficiency and CO2 emissions per kW·h of the present system are 39.97%, 38.94% and 85.27 g/(kW·h), respectively, which are 2.33%, 2.34% higher and 5.27 g/(kW·h) lower than the reference system. The superior performance of the present system comes mainly from the significant reduction in the irreversible losses of its gasification process, which is 62.13% of the reference system. The analysis further indicates that the system net power generation efficiency reaches an optimal 41.3% under the steam-to-carbon ratio of 1.4 and the carbon capture ratio of 80% at the gasification temperature of 1 200 ℃. As the carbon capture ratio increases, the net power generation efficiency and CO2 emissions per kW·h both decrease, the latter with a minimum of 51.1 g/(kW·h).
  • Green Energy and Low-carbon Technology
    Dynamic Modeling and Multi-objective Optimization of Waste Incinerator Combustion Process Based on ISSA-ELM-NARMAX
    ZHAO Zheng, LIU Saiheng, WANG Jin, WEI Qiang, XU Hongbin
    2024, 44(8): 1264-1271. https://doi.org/10.19805/j.cnki.jcspe.2024.230437
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    In order to realize stable, efficient and environmentally friendly coordination of waste incinerator power generation units, multi-objective optimization was conducted for combustion process of the incinerator. A dynamic modeling method combining extreme learning machine (ELM) and nonlinear autoregressive moving average model with exogenous inputs (NARMAX) was proposed, and the parameters of the model are optimized by improved sparrow algorithm (ISSA). The dynamic models of steam flow, boiler efficiency and first flue temperature of the incinerator were established respectively. The ISSA-ELM-NARMAX model was compared with the traditional BP neural network model, ELM-NARMAX model and SSA-ELM-NARMAX model. Finally, multi-objective optimization of the combustion process was carried out to find the optimal operating parameters of the incinerator based on the improved non-dominated sorting genetic algorithm (NSGA-II). Results show that the dynamic model of combustion process of the incinerator based on ISSA-ELM-NARMAX is more accurate and effective, and the proposed control strategy can provide operational guidance for the incinerator operators.
    • Integrated Energy System
  • Integrated Energy System
    Test and Research on the Performance of Large Steam Ejector for Exhaust Steam Heating
    ZHANG Pan, LÜ Junfu
    2024, 44(8): 1272-1277. https://doi.org/10.19805/j.cnki.jcspe.2024.230427
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    Comprehensive analysis and research were carried out on the performance of large-scale steam ejectors for exhaust steam heat-supply. Based on the inherent characteristics of the steam injector, the performance of the ejector in the exhaust steam heat supply system of a 300 MW class unit under off-design conditions was experimentally studied. The performance curves of the steam ejector under different turbine back pressures, power steam pressures and outlet pressures were obtained. A solution method for full-operation-condition performance parameters of the steam ejector was established. Results show that the performance parameters are in good agreement with the experimental data.
  • Integrated Energy System
    Thermodynamic Analysis and Optimization of a Combined Cooling, Heating, Power and Hydrogen Poly-generation System with Photovoltaic and Grid Complementary for the Chlor-Alkali Chemical Industry
    LI Xiang, XIN Yu, XING Xueli, WANG Chaowei, HONG Hui, GAO Lin, WU Cong, YUAN Bo
    2024, 44(8): 1278-1286. https://doi.org/10.19805/j.cnki.jcspe.2024.230387
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    A combined cooling, heating, power and hydrogen poly-generation system with photovoltaic and grid complementary for the chlor-alkali chemical industry was proposed. By establishing the thermodynamic model, the influence of different key parameters on the performance of each unit of the system was explored, and the operation strategy of the system was analyzed. Results show that compared with the conventional chlor-alkali system, the energy utilization efficiency of the poly-generation system is improved by 14.65%, annual carbon emission is reduced by 31%, and daily power purchase costs are reduced by 25.4%-51.1%.
  • Integrated Energy System
    Optimal Scheduling of Integrated Energy Systems Considering Coupled Power to Gas, Carbon Capture System, and Combined Heating and Power Flexible Outputs Under Stepped Carbon
    ZHAO Zhenyu, DENG Hanyu
    2024, 44(8): 1287-1297. https://doi.org/10.19805/j.cnki.jcspe.2024.230380
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    Under the "dual carbon" goal of China, to further reduce the carbon emissions of the integrated energy system (IES) and enhance the accommodation capacity of renewable energy, a low-carbon economic operation optimization strategy for IES was proposed. Firstly, a stair-like carbon trading mechanism was introduced to constrain the carbon emissions of IES; Then the coupled power to gas (P2G) and carbon capture system (CCS) model was established, and the two-stage operation of P2G was refined; Next, the Karina cycle and electric boiler were introduced to operate jointly in traditional combined heat and power (CHP) units, and a CHP model with flexible heating and power outputs was constructed; Finally, with the optimization goal of minimizing the sum of system operation and maintenance costs, carbon trading costs, energy purchase costs, and wind and solar abandonment costs, an IES low-carbon economy scheduling model was constructed, and different operating scenarios were set for comparative analysis. Results show that the carbon emissions of IES are reduced by 38.45%, and the total operating cost is reduced by 10.37%, verifying the low-carbon and economic performance of the established model.
  • Integrated Energy System
    Multi-objective Optimization of S-CO2 Recompression and Reheat Coal-fired System Based on NSGA-Ⅱ Algorithm
    YANG Yilin, LI Peng, LIU Shitong, BAI Yaping, ZHAO Wensheng, HAN Zhonghe
    2024, 44(8): 1298-1306. https://doi.org/10.19805/j.cnki.jcspe.2024.230435
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    Taking the coal-fired thermodynamic system of S-CO2 recompression and reheat cycle as the research object, and the cycle efficiency (ηt) and levelized cost of energy (CLCOE) as the thermodynamic and economic performance indexes of the system, the influence laws of the system key parameters on the thermodynamic and economic performance of the system were analyzed. A multi-objective optimization model of S-CO2 recompression and reheat cycle coal-fired thermodynamic system was established based on NSGA-II algorithm. Aiming at the thermodynamic performance and economy of the system, the optimal solutions of the system key parameters were obtained. Finally, the multi-objective optimization of the system was carried out by taking reheat temperature, turbine inlet temperature, main compressor outlet pressure, reheat pressure, main compressor inlet pressure, main compressor inlet temperature and split-flow coefficient as the decision variables. Results show that the cycle efficiency and levelized cost of energy of the system increase with the increase of turbine inlet temperature and reheat temperature, thus thermodynamic performance and economy of the system cannot be optimized simultaneously. The multi-objective optimization results of ηt and CLCOE are 53.07% and 453.43 yuan/(MW·h). Compared with the design condition, ηt is increased by 5.42% and CLCOE is decreased by 5.91%.
  • Integrated Energy System
    Thermodynamic Analysis and Optimization of Semi-closed CO2 Cycle Power Generation System Integrated with LNG Cold Energy for Air Separation Process
    XU Hongyu, LI Ruifan, XU Cheng, GUO Hao, XIN Tuantuan, YANG Yongping
    2024, 44(8): 1307-1316. https://doi.org/10.19805/j.cnki.jcspe.2024.230382
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    Considering the characteristics of high efficiency and zero carbon emissions of the semi-closed CO2 cycle, and based on the semi-closed CO2 power generation system integrated with liquefied natural gas (LNG) cold energy at present, an efficient utilization way of LNG cold energy was proposed. Results show that, for the base case, the energy consumptions of the air separation and compression processes are reduced by 70.4 and 75 MW, respectively, and with a net system efficiency of 63.76%, which is 9.48 percentage points higher than the conventional cycle. Furthermore, with optimization measures such as improving the system parameters and matching the heat capacities of regenerators, the net efficiency of the optimized case is further increased to 72.22%, and the exergy efficiency is 51.27%. Compared with the reference system Ⅱ of only integrating LNG cold energy within the power cycle, the exergy efficiency of cold energy utilization is improved by 28 percentage points.