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    Fundamental Research
  • Fundamental Research
    Numerical Analysis of Gas-Solid Flow and Chemical Reaction Characteristics of Air Reactor Based on EMMS-1M Tracing Force Model
    LI Huijun, WANG Yeku, LU Xuao, ZHANG Jiuyi
    2023, 43(7): 815-822. https://doi.org/10.19805/j.cnki.jcspe.2023.07.001
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    Aiming at the problem that the conventional drag force model is difficult to accurately predict the gas-solid interphase drag force, considering the calculation accuracy and model generality, the EMMS-1M drag force model with mesoscale correction coupled with the two-fluid model was chosen to simulate the effects of particle size and inlet gas velocity on the cold-state fluidization and thermal chemical reactions in the air reactor. Results show that:the decrease of particle size and increase of inlet gas velocity result in uniform bed gas pressure distribution; the bed axial particle concentration decreases, the bed particle mixing return phenomenon can be weakened, and the axial velocity of particles increases. Increasing temperature promotes the reaction to proceed positively and increases the oxygen conversion rate. The increase of inlet gas velocity leads to uniform particle distribution in the bed and complete gas-solid mixing, which promotes the chemical reaction. However, too high inlet gas velocity carries out many particles, and the residence time in the bed is reduced, which is not conducive to the occurrence of the gas-solid chemical reaction.
    • Power Equipment and System
  • Power Equipment and System
    Investigation on the Criterion of the Air Distribution Uniformity in a Circulating Fluidized Bed Boiler and the Improved Test Method
    TONG Boheng, LI Jinjing, CHENG Tongrui, ZHAO Zhenning, CHENG Liang, LÜ Junfu
    2023, 43(7): 823-828. https://doi.org/10.19805/j.cnki.jcspe.2023.07.002
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    Using the method of numerical simulation, the influence of the deviation of the primary air volume of the circulating fluidized bed (CFB) boiler on the fluidization uniformity was studied, the criterion for the material layer thickness deviation of the air distribution uniformity was proposed, and then the improved test method of the air distribution uniformity of the circulating fluidized bed boiler was proposed. Results show that when the deviation of the inlet flow on both sides of the primary air chamber exceeds 10%, the fluidization uniformity of the bed material is worse. At this moment, it corresponds to the maximum allowable deviation of the air distribution uniformity, namely the difference between the maximum and minimum bed material heights should not exceed 20 cm, and the maximum deviation between the height of the bed material and the average height should not exceed 12 cm.
  • Power Equipment and System
    Experimental Research of High Temperature Dust Removal Technology in a 410 t/h Coal-fired Power Station
    SI Tong, WANG Chunbo, CHEN Liang, REN Yujie, REN Fuchun
    2023, 43(7): 829-834. https://doi.org/10.19805/j.cnki.jcspe.2023.07.003
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    For the problems of the shortened catalyst service life, a large amount of ammonia escape and the blockage of air preheater caused by high concentration fly ash in selective catalytic reduction (SCR) denitration technology of the coal-fired power station, the high temperature dust collector was arranged in front of the SCR reactor. An engineering study of high temperature dust removal technology was demonstrated on a 410 t/h coal-fired boiler, and the influence of the dust removal characteristics of the high temperature dust collector on the performance of the downstream denitrification unit and air preheater was analyzed. Results show that the average mass concentration of particulate matter at the outlet of the high temperature precipitator is less than 8 mg/m3 under 70% and 90% boiler load. The pressure drop of flue gas flowing through the high temperature dust collector is about 500 Pa under 90% boiler load, which is much lower than that of the traditional bag dust collector. Compared with the typical post-treatment technology of flue gas with ultralow emission, the application of high temperature dust collector can significantly decrease the flue gas pressure drop of SCR reactor under the same denitration efficiency, and reduce the corresponding gaseous ammonia consumption and ammonia escape. Compared with the conventional arrangement of bag dust collector, the total pressure drop of high temperature dust collector, SCR denitration unit and air preheater can be approximately decreased by 500 Pa.
  • Power Equipment and System
    Experimental Identification for Direct Stiffness Coefficient of the Labyrinth Seal
    ZHOU Qinghui, ZHANG Wanfu, YANG Xingchen, PAN Bo
    2023, 43(7): 835-841. https://doi.org/10.19805/j.cnki.jcspe.2023.07.004
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    A test rig for identification of the direct stiffness coefficient of the labyrinth seal was designed and built. The influence of the excitation frequency and inlet pressure on the direct stiffness coefficient at different rotational speeds was studied. The experimental results were compared with the theoretical calculation of the Bulk Flow model in DyRoBeS. Results show that the direct stiffness coefficient of the labyrinth seal is negative under any operating conditions, which makes it prone to rotor instability. The direct stiffness coefficient decreases with increasing rotational speed, inlet pressure and excitation frequency. The rotational speed has little influence on the direct stiffness coefficient. And the direct stiffness coefficient is highly dependent on the high excitation frequency. The theoretical prediction calculation of DyRoBeS shows good agreement with the experimental measurements.
  • Power Equipment and System
    Prediction and Analysis of Combustion Stability of Gas Turbine Based on Neural Network
    WANG Wenyang
    2023, 43(7): 842-849. https://doi.org/10.19805/j.cnki.jcspe.2023.07.005
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    In terms of instability and difficulty in timely intervention during the combustion adjustment process, based on the characteristics of a certain type of gas turbine combustion adjustment process, an improved particle swarm optimization (PSO) algorithm was used to optimize Elman neural network. The parameters that affect the operating state of the unit were used as input variables, and the parameters that characterize combustion stability were used as output variables, thereby establishing an improved PSO-Elman neural network model. Result shows that the mass flow rate of the duty air, the opening of the compressor inlet guide vanes (IGV) and the first stage adjustable stationary blade of the compressor (CV1) have a significant impact on combustion stability. Compared with Elman neural network, the improved PSO-Elman neural network model has better reliability. The proposed model can well track the change characteristics of parameters during combustion adjustment, which can be used to predict possible combustion instability in advance, and solve the technical problems related with limitations and poor flexibility in the test process.
  • Power Equipment and System
    Numerical Simulation of the Influence of Water Spray Precooling Characteristics on Evaporative Cooling Performance
    LI Hengfan, LI Yulong, HAN Zhonghe
    2023, 43(7): 850-857. https://doi.org/10.19805/j.cnki.jcspe.2023.07.006
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    In order to improve the cooling performance of indirect air cooling tower in high temperature environment of summer, so as to improve the overall efficiency of thermal power plant, the numerical model of water spray precooling system of air cooling unit was established based on computational fluid dynamics. The influence of water spray precooling characteristics on a certain sector of air cooling tower was analyzed, and the effects of environmental characteristics and nozzle characteristics on cooling efficiency, temperature drop and area of effective cooling area were calculated, respectively. Results show that the cooling efficiency increases with the increase of flow distance. The cooling efficiency can be improved when the ambient wind speed and air humidity decrease, the wind temperature, the opening angle, the mass flow and spacing of the nozzle increase. The droplets gradually evaporate with the flow of air, and the area of the effective cooling area gradually increases along the flow direction. The effective temperature drop first increases along the flow direction due to the evaporation of droplets, and then decreases due to the heat and mass transfer between the cooled air and the surrounding air.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Performance Analysis of a Solar-aided Waste-to-Energy Power Generation System
    WU Yunyun, WANG Yihan, CHEN Heng, HAO Yong
    2023, 43(7): 858-868. https://doi.org/10.19805/j.cnki.jcspe.2023.07.007
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    A solar-aided municipal solid waste incineration power generation system has been proposed for advancing the waste-to-energy and solar thermal energy technologies. This system could use the heat obtained by the parabolic trough collectors to reheat the working steam in the incineration plant and improve the steam parameters. A waste-to-energy power plant with the waste treatment capacity of 550 t/d and net generating power of 8.97 MW was used as a reference unit, coupled with solar assisted reheat system with input of 5.91 MW solar energy. Thermodynamic and sensitive analyses were conducted to examine the performance of the proposed system under various solar conditions and reveal the performance enhancement mechanism. Results show that compared with the reference system, the proposed system improves the ideal steam cycle efficiency by 0.96% and net generating power by 1.36 MW with solar-to-electricity efficiency of 22.91% under the design condition. The proposed system performs well for most of the year. And the annual solar-to-electricity efficiency of 17.45% is achieved. The levelized cost of electricity of the proposed system is 0.757 Yuan/(kW·h), which is economically feasible.
  • New Energy Resources and Energy Storage
    Dynamic Simulation and Efficiency Analysis of Energy Release Process in Compressed Air Energy Storage Under Multi Conditions
    CHEN Hui, LI Wen, SHENG Yong, WANG Xing, CHEN Haisheng, ZHU Yangli
    2023, 43(7): 869-876. https://doi.org/10.19805/j.cnki.jcspe.2023.07.008
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    The mathematical model and control logic of energy release process in compressed air energy storage (CAES) were studied. The dynamic simulation model of CAES energy release process was established using MATLAB/Simulink platform for the simulation of start-up process, quasi-synchronized grid connection process and off-design condition process. The variation of operating parameters and efficiency under multi conditions were analyzed. Results show that within the power range of 200-300 kW, the expander efficiency is in the range of 75%-88%, and the exergy efficiency is in the range of 73%-84%.
  • New Energy Resources and Energy Storage
    Capacity Configuration Method of Flywheel Energy Storage Array for Assisting the Primary Frequency Regulation of Nuclear Power Unit
    WU Xin, YANG Weipeng, XIONG Xingyu, MA Zhiyong, ZHANG Shuang, LUO Hairong
    2023, 43(7): 877-884. https://doi.org/10.19805/j.cnki.jcspe.2023.07.009
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    Considering the insufficient primary frequency regulation capability of nuclear power unit, the flywheel energy storage array was used to assist its primary frequency regulation. The 1 MW/250 kW·h flywheel energy storage unit model and 4 MW/1 MW·h flywheel energy storage array were established, so as to analyze their charge and discharge characteristics. In order to improve the integral power contribution index of the primary frequency regulation of nuclear power unit by twice, the capacity configuration method of flywheel energy storage array was propose based on particle filtering method. According to the historical operation data of a nuclear power unit with installed capacity of 1 250 MW, the simulation was performed to verify the proposed method. Results show that compared with the capacity configuration method of flywheel energy storage array using the ensemble empirical mode decomposition (EEMD) method, the proposed method shows better performance of frequency regulation.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Abnormal Wind Turbine Data Identification Using a Dirichlet Process Gaussian Mixture Model Based on Variational Bayesian Inference
    GAN Yu, GUO Peng, LIN Lidong
    2023, 43(7): 885-892. https://doi.org/10.19805/j.cnki.jcspe.2023.07.010
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    In order to accurately identify and eliminate abnormal data generated by wind turbines in the actual operation process, so as to provide effective data support for power prediction and other work, an abnormal data identification method using a Dirichlet process Gaussian mixture model (DPGMM) based on variational Bayesian inference was proposed by analyzing the distribution characteristics of wind turbine operational data points in a wind speed-power (v-P) coordinate system. The measured data scattered points of test unit E17 were divided along the horizontal power direction at a certain interval, and the data scattered points in each power range were clustered by using DPGMM that can adaptively determine the optimal number of components, the confidence ellipse parameters of each Gaussian component and the distribution characteristics of data scattered points in the v-P coordinate system were combined, so as to identify anomalies in the Gaussian components and their clustering scattered points in each power range of the test unit E17. Results show that the model overcomes the shortcoming of the traditional Gaussian mixture model that the number of components needs to be determined manually, and the new model can accurately identify abnormal wind turbine data.
  • Digitalization and Intelligentization
    Research on Optimal Control of Improved Linear Active Disturbance Rejection for SCR Denitrification System
    YANG Chaojie, LIU Changliang, WANG Ziqi, HAN Chao
    2023, 43(7): 893-900. https://doi.org/10.19805/j.cnki.jcspe.2023.07.011
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    To solve the problems of large inertia, large delay and multiple disturbances in SCR denitration system, a model-aided delay linear active disturbance rejection control (MDLADRC) was proposed. Firstly, the higher-order pure-delay system was compensated as a first-order inertial link using the model information. Secondly, according to the two-degree-of-freedom expression of the closed-loop system, the optimal parameter quantification formula was deduced. The parameter adjustment was simplified, and the relationship between the controller parameters and the response index was verified by parameter traversal experiments. Finally, MDLADRC was applied to the SCR denitration control system to compare the performance with various controllers. Results show that for high-order large-inertia and large-delay systems such as SCR denitration, MDLADRC has better fixed value following and anti-interference ability. Monte Carlo experiments and multi-condition experiments further illustrate the robustness of MDLADRC. In addition, the parameter adjustment of MDLADRC is simple, and is more suitable for engineering practice.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Low-carbon Economic Dispatch of Integrated Energy System Based on Ladder-type Carbon Trading Mechanism
    CHEN Yanqi, LIU Kangxiang, ZHAO Xin, XU Gang, CHEN Heng, LIU Wenyi
    2023, 43(7): 901-909. https://doi.org/10.19805/j.cnki.jcspe.2023.07.012
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    In order to realize the economical and low-carbon operation of the integrated energy system, an integrated energy system optimization model considering the stepped carbon trading mechanism was proposed. Firstly, the goal was to minimize the annual operation and maintenance costs of the system and investment costs. An energy system capacity optimization model was established considering multiple load demands. Secondly, the typical daily cooling and heating loads were selected based on the k-means clustering method and the average method. Finally, the minimum system operation and maintenance costs and carbon trading costs were targeted to analyze the impact of different benchmark carbon prices on system operation, carbon emissions and economic efficiency, and conducted a detailed analysis on a typical day. Results show that the introduction of the stepped carbon trading mechanism into the integrated energy system can effectively reduce carbon emissions and improve the economy of the system, especially in the heating season, which can have a significant impact on the system with a lower benchmark carbon price.
  • Green Energy and Low-carbon Technology
    NOx Prediction Model for Coal-fired Boiler Based on Bayesian Optimization-Random Forest Regression
    SUN Hubin, YANG Jianguo, JIN Hongwei, TU Haibiao, ZHOU Xiaoliang, ZHAO Hong
    2023, 43(7): 910-916. https://doi.org/10.19805/j.cnki.jcspe.2023.07.013
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    Based on the actual operating data of a coal-fired boiler in a 1 050 MW ultra-supercritical unit, a random forest (RF) algorithm was used to establish a prediction model for NOx concentration in the flue gas at the furnace outlet of the coal-fired boiler, and Bayesian optimization (BO) was used to optimize the hyperparameters. Then the BO-RF model was compared with the grid search optimized RF model (GSO-RF). In order to better evaluate the prediction model, the established BO-RF model was compared with the current common error Bayesian optimized back propagation neural network (BO-BPNN) model and Bayesian optimized least square support vector machine (BO-LSSVM) model, using the average absolute percentage error δMAPE and the coefficient of determination R2 as evaluation indicators. Results show that the prediction accuracy of the BO-RF model is higher than that of the GSO-RF model, and the δMAPE of the BO-RF model is 1.478%, the R2 is 0.916 2, which are better than the prediction results of the BO-BPNN model and the BO-LSSVM model, indicating that the BO-RF model has higher prediction accuracy and better generalization performance.
  • Green Energy and Low-carbon Technology
    Study on Prediction of Ammonia Escape from Thermal Power Plants
    TAN Zengqiang, NIU Yongjun, LI Yuanhao, QU Feiyu
    2023, 43(7): 917-922. https://doi.org/10.19805/j.cnki.jcspe.2023.07.014
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    To achieve safe and stable operation of thermal power plant with ultra-low emissions, a long short-term memory(LSTM) model and a support vector regression(SVR) model for predicting ammonia escape were constructed respectively, based on the distributed control system(DCS) data including the flue gas temperature and O2 concentration at the denitration inlet, the NOx concentration at the denitration inlet and outlet, the amount of ammonia injection, and the pressure difference of the air preheater. According to the NOx concentration and ammonia escape of the SCR denitration inlet and outlet tested on site, the macroscopic denitration device potential was calculated, the ammonia escape concentration was calculated in combination with the DCS data in the same period, which was used as the real value compared with the forecasting results of the LSTM model and the SVR model. Results show that the SVR model has high accuracy and generalization ability for the prediction of ammonia escape. The prediction errors of the SVR model for the test samples are:δMRE=0.007 1 μL/L, δMAE=0.002 4 μL/L. The prediction error of the LSTM model for the test sample are:δMRE=0.047 0 μL/L, δMAE=0.019 0 μL/L.
    • Integrated Energy System
  • Integrated Energy System
    Optimal Configuration of Urban Building CCHP System Based on Exhaustive Search Method
    HAN Xu, ZHOU Junyi, WANG Xiaodong, WU Di, LI Peng, HAN Zhonghe
    2023, 43(7): 923-929. https://doi.org/10.19805/j.cnki.jcspe.2023.07.015
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    Combined cooling, heating and power (CCHP) system can realize efficient cascade utilization of energy, which was conducive to achieve the goal of "carbon peak and carbon neutrality". Based on the exhaustive search method, a building-level CCHP system was constructed including gas-fired cogeneration system, gas-fired boiler, electric chiller, absorption chiller and water-water heat exchanger. Taking three typical buildings as research objects, the capacity configuration, system operation parameters, economic performance and emission reduction of the CCHP system were studied and the corresponding sensitivity analysis was carried out. Results show that compared with their production systems, the cost saving rates of commercial buildings, office buildings and residential buildings are 21.76%, 16.72% and 9.17%, the carbon dioxide emission reduction rates are 15.80%, 10.42% and 4.41%, and the system energy prices are reduced by 39.85%, 49.04% and 41.29%, respectively. The research results can provide a reference for the optimization of the CCHP system.
  • Integrated Energy System
    Research on Hybrid Time Scale Rolling Optimal Operation of CCHP System with Photovoltaic and Energy Storage
    WANG Zhi, CAI Wenkui, MENG Jinxiang, WU Yuxiao, WU Di
    2023, 43(7): 930-940. https://doi.org/10.19805/j.cnki.jcspe.2023.07.016
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    To solve the problem of significant difference in energy matching between supply and demand in combined cooling heating and power system, a three-stage hybrid time scale rolling optimization method was proposed. In the day-ahead stage, the lowest daily operation cost was taken as the optimization objective, the treatment costs of CO2, SO2 and NOx were considered and the hourly plan was formulated. According to the response speed difference of cooling, heating and power related equipment, a bi-level optimization model of time-scale decomposition was established at intra-day stage. The optimization objective was selected as the minimum power adjustment of electrical equipment in real-time electrical feedback optimization and the best output plan for each device was obtained. Results show that the three-stage hybrid time scale rolling optimization method can effectively suppress the fluctuation of load and renewable energy output, and the power fluctuation rate of each equipment is at a low level; the daily operating costs of different typical days are lower than the day-ahead costs, and the cost-saving rate of typical days in winter, transition season and summer are 0.99%, 1.10% and 2.01%, respectively.
  • Integrated Energy System
    Research on Structural Optimization of Steam Ejector for Cogeneration
    PANG Jingshuai, XIONG Nian, ZHANG Youjun, GE Zhihua, DU Xiaoze
    2023, 43(7): 941-950. https://doi.org/10.19805/j.cnki.jcspe.2023.07.017
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    In order to improve the performance of the steam ejector in the cogeneration system, the different structural parameters of the ejector were optimized. Taking a typical 2×350 MW cogeneration unit as an example, the design parameters of the ejector were determined and a numerical model was established. The effects of structural parameters such as the diameter of the constant section mixing cavity, nozzle exit position, and inlet angle of the mixing cavity on the ejector performance were analyzed using single-factor structural optimization. Multi-factor structural optimization was then carried out through the orthogonal test to gain the sensitivity of each factor and the relatively optimal structural combination. On this basis, the ejector applicability and operation strategy were investigated under variable working conditions of cogeneration units. Results show that the multi-factor structure optimization can further improve the entrainment ratio to 0.945, an increase of 18.7% compared with the original ejector, and the performance of the ejector is significantly improved. The motive steam pressure and outlet back pressure of the ejector shall fall in a rational range to obtain a higher entrainment ratio under variable working conditions of cogeneration units. It is not very operable to improve the performance of the ejector by increasing the suction steam pressure in practical applications.
  • Integrated Energy System
    Research on Operating Characteristics of Coupled Absorption Heat Pump for Cogeneration Units
    LI Wei, YANG Cunhui, WU Guolin, WANG Haihong, MEI Chuansong, ZHAO Yongliang, SHENG Deren
    2023, 43(7): 951-958. https://doi.org/10.19805/j.cnki.jcspe.2023.07.018
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    Aiming at improving the economy of cogeneration unit coupled absorption heat pump, the thermal model of the unit was built based on Ebsilon; the influence of internal and external parameters on the heat pump efficiency and thermal economy was analyzed using the control variates method; the research was conducted combined with the actual operation data of a 2×350 MW cogeneration unit. Results show that under the rated heating condition, the extraction steam of the coupled absorption heat pump can be saved by about 18% and the thermal efficiency of the unit can be increased by 1.2% compared with that of the heating network heater only; The return water temperature of the heat supply network increases by 10 K, resulting in that the performance coefficient (COP) of the heat pump decreases by about 0.1% and the thermal economy of the unit decreases by about 4%. The reduction of the thermal economy of the unit can be reduced by increasing the heat supply load of the heat pump; Increasing the temperature of the low-temperature circulating water increases both the COP of the heat pump and the thermal economy of the unit. When the difference between the return water temperature of the heat supply network and the temperature of the low-temperature circulating water is less than 10 K, the effect of improving the heating performance is not obvious; When the outlet steam temperature of the heat pump generator increases by 10 K, the COP of the heat pump increases by 18.9%, but the steam consumption of the unit increases by about 1%. Therefore, by adjusting the operating parameters of the heat pump, more waste heat of circulating cooling water can be extracted, the output of the heating network heater can be reduced, and the cold end loss of the unit is reduced.