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    Fundamental Research
  • Fundamental Research
    Study on Corrosion Characteristics of Heat-resistant Materials in Supercritical Carbon Dioxide Environment Containing Oxygen Impurities
    WANG Mingxuan, MOU Wenbiao, LIU Yafei, XIAO Gang
    2023, 43(4): 391-396. https://doi.org/10.19805/j.cnki.jcspe.2023.04.001
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    In order to study the effect of oxygen impurities on corrosion behavior, the platform for supercritical carbon dioxide corrosion experiment was built. The effect of oxygen impurities on the corrosion characteristics of heat-resistant steel T91, 310S and Inconel 625 was studied in supercritical carbon dioxide environment with oxygen concentration of 10-4. The corrosion mass increase, phase composition of corrosion products, surface morphology and element distribution were analyzed by means of weighing, X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. Results show that the corrosion mass increase of T91, 310S and Inconel 625 in supercritical carbon dioxide environment containing oxygen impurities was 1.36, 1.55 and 3.19 times higher than that in high-purity carbon dioxide environment, respectively. In supercritical carbon dioxide environment containing oxygen impurities, the content of Fe2O3 in T91 corrosion products increases, a large amount of vane-like Cr2O3 appeares on 310S surface, and nodules on the surface of Inconel 625 disappear. Compared with the high-purity carbon dioxide environment, the mass fraction of carbon on the surface of the three materials has been greatly reduced to about 5% in supercritical carbon dioxide environment containing oxygen impurities. Besides, the corrosion mass increase curves of three materials obey the parabolic law, and the corrosion resistance of 310S and Inconel 625 is significantly better than that of T91.
  • Fundamental Research
    Topology Optimization of Heat Conduction Fins in Three-tube Phase Change Heat Accumulator
    YAO Li, ZHANG Fengming, ZHAO Ming
    2023, 43(4): 397-405. https://doi.org/10.19805/j.cnki.jcspe.2023.04.002
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    The fin structure of the three-tube phase change heat accumulator was optimized by using the topology optimization method based on the model of solid isotropic microstructure with penalization (SIMP). The geometric reconstruction was carried out, and compared with the other three traditional fin models. Results show that the heat storage and release process of the geometrically reconstructed model is consistent with the topology optimization results, the temperature uniformity is also significantly improved. The complete melting time is relatively reduced by 68.6%, and the complete solidification time is relatively reduced by 80.4%. The distribution uniformity in the phase change heat accumulator has an important influence on the heat storage and release performance. The model based on the uniform distribution design principle has better heat storage and release performance. The reconstructed model based on topology optimization has the least number of fins and the highest heat storage advantages in general.
  • Fundamental Research
    Study on Corrosion Characteristics of Nickel-based Alloy Inconel 617 in High-temperature Supercritical Carbon Dioxide
    XIAO Bo, WANG Bihui, CEN Dongliang, ZHU Zhongliang, ZHANG Naiqiang
    2023, 43(4): 406-413. https://doi.org/10.19805/j.cnki.jcspe.2023.04.003
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    The oxide corrosion experiment was carried out on Inconel 617 nickel-based alloy in supercritical carbon dioxide environment at 550-700 ℃ and 15-25 MPa for 1 000 h. Then oxidation curves of alloy were obtained. The oxide scale morphology, phase and composition were analyzed by means such as SEM、EDS、XRD and AFM. Results show that the oxidation rate is significantly affected by temperature. Oxidation kinetics exhibits the cubic rule at 700 ℃. The alloy forms a compact monolayer oxide film structure at all temperatures. With the increase of temperature, a few holes appear at the lower grain boundary. There are mainly Ti-rich nodular oxides on the surface of the alloy and Al oxide enrichment in grain boundary pores below.
  • Fundamental Research
    Experimental Study on Corrosion Fatigue Crack Growth Rate of Nickel-based 617 Alloy Candidate for Advanced Ultra Supercritical Units in Supercritical Water
    CHEN Zhenyu, ZHANG Naiqiang, ZHOU Mi, LIU Yutong
    2023, 43(4): 414-420. https://doi.org/10.19805/j.cnki.jcspe.2023.04.004
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    The corrosion fatigue crack growth rate (CFCGR) of a candidate nickel-based alloy Inconel 617 for advanced ultra supercritical units in 650 ℃/25 MPa supercritical water was studied. The constant stress intensity factor (K) method was used for dynamic loading, the DC potential drop (DCPD) method was used to measure the crack length in real time, the CFCGR under each condition was calculated by linear regression method, and the effects of loading frequency (1.00 Hz, 0.10 Hz and 0.01 Hz) and waveform (sine wave, triangular wave and trapezoidal wave) on CFCGR were explored. Results show that the CFCGR decreases with the increase of loading frequency, and the relationship between CFCGR and loading frequency is logarithmic linear. At three frequencies, sine wave and triangular wave loading have no significant effect on the CFCGR, and this waveform independence is established in a wide frequency range. Trapezoidal wave has greater CFCGR than continuous cycles without holding time.
    • Power Equipment and System
  • Power Equipment and System
    Process Parameter Optimization of Zr Coating on SP-700 Titanium Alloy by Laser Cladding on the Last Stage Blade of Steam Turbine
    LI Cong, NIE Bingyue, LI Hu, LI Wei, CHEN Wei, ZHOU Libo, CHEN Jian
    2023, 43(4): 421-429. https://doi.org/10.19805/j.cnki.jcspe.2023.04.005
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    Zr coating layer was prepared on SP-700 titanium alloy by laser cladding. The effect of scanning speed and powder feeding rate on the coating morphology was studied to obtain the best process. The characteristic parameters such as lap width, melting thickness and crack rate were obtained by optical microscopy. The structure, melting thickness and interface of the under layer at different scanning speed and powder feeding rates were characterized by scanning electron microscopy(SEM). The microhardness, friction coefficient, wear morphology and wear resistance of the cladding layer were determined by vickers microhardness meter, reciprocating friction tester and laser confocal microscopy. Results show that at the scanning speed of 6 mm/s and the rotation rate of powder feeder of 4 r/min, better surface forming quality, medium melting thickness and lap width, lower crack rate of the cladding layer, uniform microstructure, clear crystal, low dispersion and higher microhardness can be achieved. The microhardness of coating layer is 1.8 times higher than the matrix. The morphology of friction and wear is good. No obvious defects are detected. The wear resistance is better.
  • Power Equipment and System
    Calculation Method and Experimental Research on Jacking Oil of Sliding Bearing with Double Jacking Oil Pockets
    YAN Weichun
    2023, 43(4): 430-435. https://doi.org/10.19805/j.cnki.jcspe.2023.04.006
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    In order to obtain a calculation method for jacking oil of sliding bearing with double jacking shaft oil pockets that could be used in engineering applications, theoretical and experimental researches were carried out. Two theoretical calculation methods were proposed: one was to deduce the calculation formula of double oil pockets based on the calculation formula of single oil pocket| the other was to establish the mathematical model of double oil pocket calculation by numerical calculation. The related experiments on the relationship between the jacking oil pressure, the jacking oil volume flow rate and the bearing load, the rotor jacking height were designed, and the theoretical calculation values were compared and analyzed. Results show that the jacking oil pressure obtained by theoretical method and test are relatively close, and the test value is slightly smaller. There is a big difference between the jacking oil volume flow rate obtained by theoretical method and test, and the test value is 1.5-2.5 times of the theoretically calculated value. The jacking oil volume flow rate has an exponential relationship with the rotor jacking height in the test| in engineering applications, the derived formula can be used to calculate the jacking oil pressure and volume flow rate, but a certain margin should be left when calculating the jacking oil volume flow rate. Considering the economical efficiency, the rotor jacking height should not be set too high.
  • Power Equipment and System
    Prediction Method of Condenser Vacuum Based on GWO-RF
    LI Wangfan, DING Xian, FANG Jingjian
    2023, 43(4): 436-442. https://doi.org/10.19805/j.cnki.jcspe.2023.04.007
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    In order to improve the performance of condenser vacuum prediction model under different operating conditions, Spearman correlation coefficient was used to judge the correlation between condenser vacuum and feature values, and the combination of different characteristic values was selected, random forest(RF) was used to establish the prediction model, and gray wolf optimization algorithm(GWO) optimization function was introduced to optimize the model parameters. And a vacuum prediction model was established by taking the condenser operation data of a 1 000 MW unit as an example. The results show that the maximum absolute error of the vacuum prediction model based on GWO-RF is 0.152 0 kPa, which has certain validity and generalization. According to the difference of Spearman correlation coefficient between each feature value and the target value, reducing the input of some feature values with weak correlation can effectively reduce the training time, and the model accuracy changes little. The condenser vacuum prediction model based on GWO-RF has good prediction effect in different load sections, with relative error of [-0.16%, 0.14%], and the best prediction effect in intermediate load section, with average relative error of 0.012%.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Study on Operation Characteristics of Wind Turbine with Control System Under Different Time-varying Inflow
    LIU Songyang, XIN Zhiqiang, LIAO Shenghai, HUANG Guoqing, CAI Zhiming
    2023, 43(4): 443-451. https://doi.org/10.19805/j.cnki.jcspe.2023.04.008
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    In order to study the effects of autonomous control system for the wind turbine under different time-varying inflow conditions, the aerodynamic performance of the wind turbine was investigated using the actuator line method and large eddy simulation based on the NREL-5 MW wind turbine model. Considering the time-varying sinusoidal inflow and the atmospheric boundary layer inflow with constant average wind speed, the operation characteristics of wind turbines with and without control conditions were simulated under three average wind speeds: high、medium and low. Results show that for the time-varying sinusoidal inflow, the control system enables the wind turbine to adapt well to different inflow wind speeds. The control system has a delayed response to wind speed fluctuations caused by the turbulence under the infow of the real atmospheric boundary layer, and the control effect shows different characteristics under the inflow of high and low wind speeds.
  • New Energy Resources and Energy Storage
    Modeling and Prediction of Biomass Direct Fired Circulating Fluidized Bed Boiler Combustion System
    ZHANG Kaiping, GAO Mingming, LONG Jiang, ZHANG Hongfu, WANG Yake, YUE Guangxi
    2023, 43(4): 452-460. https://doi.org/10.19805/j.cnki.jcspe.2023.04.009
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    In order to analyze the internal combustion mechanism of the biomass circulating fluidized bed boiler and realize the optimization of combustion control, the combustion process and combustion mechanism in the furnace were analyzed through the analysis of the characteristics of biomass fuel and the application of the instantaneous carbon combustion theory, and the combustion process was established. The dynamic change process of carbon burning in the furnace was analyzed to realized the prediction of load, furnace temperature, carbon monoxide emission and flue gas oxygen content. Results show that the combustion rate of instant carbon formed after the fuel devolatilization is slower than that of volatile matter, and the fuel feeding fluctuation directly affects the instant carbon stock in the furnace. As the main source of heat when the feed fluctuates, the oxygen required for instant carbon combustion is less and the combustion is more sufficient. At the same time, the CO valume fraction in the flue gas is lower and the oxygen content is higher. the predicted values of furnace temperature, furnace load, CO valume fraction and flue gas oxygen content are basically the same as the actual values.
  • New Energy Resources and Energy Storage
    Heat Transfer Performance of Drum-type Porous Volumetric Solar Receiver Improved by Gradually Changed Structure
    LIU Yun, ZHAO Boyang, SHEN Wenran, XIE Lingtian, ZHAO Xu
    2023, 43(4): 461-467. https://doi.org/10.19805/j.cnki.jcspe.2023.04.010
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    A three-dimensional numerical simulation model of a drum-type porous volumetric solar receiver was established with air and SiC as heat transfer fluid and porous media. The Gaussian distribution model was used to simulate the heat flux distribution of real concentrating solar. Based on numerical calculation method, the effects of constant porosity and constant pore size structure and gradually changed porosity and gradually changed pore size structure on heat transfer performance of this solar receiver were analyzed. Results show that compared with the constant porosity and pore size, the outlet temperature of heat transfer fluid in the solar receiver with the gradually changed porosity and pore size increases by 11.47%.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Robust H∞/H2 Gain-scheduling Control of a Boiler-Turbine System Based on Linear Parameter Varying Model
    WANG Dongfeng, ZHU Weiqi
    2023, 43(4): 468-474. https://doi.org/10.19805/j.cnki.jcspe.2023.04.011
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    The global linear parameter varying (LPV) model of a boiler-turbine coordinated control system was identified by the quantum particle swarm optimization algorithm. A polytopic LPV model was obtained by the extremum disassembling and assembling. Aiming at the polytopic LPV model, the relaxation variable was introduced into the robust H∞/H2 gain-scheduling control, and a less conservative robust controller for the coordinated control system was designed. Results show that the designed controller has good control effect.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Thermodynamic Analysis of a Decarbonization System of Coal-fired Power Station Using Waste Heat and Pressure
    ZHANG Ting, XU Cheng
    2023, 43(4): 475-482. https://doi.org/10.19805/j.cnki.jcspe.2023.04.012
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    In order to reduce the carbon capture energy consumption of coal-fired power stations, a new decarbonization coal-fired system integration method and load distribution adjustment method were proposed. Taking a 600 MW coal-fired power station based on monoethanolamine (MEA) absorption method for carbon capture as an example, a system simulation was carried out to analyze the utilization of waste heat and pressure and the influence of load distribution on decarbonization energy consumption. The energy efficiency penalty of the new waste heat and pressure utilization decarbonization coal-fired power station and the coal saving of the coal-fired power station after load distribution were obtained. Results show that compared with the conventional system, the new waste heat and pressure utilization system can reduce the energy efficiency penalty by 4.58% when running at full load, and by 2.55% when running at low load. The new system using load distribution can save 1 347.48 tons of coal per year.
  • Green Energy and Low-carbon Technology
    Optimization of Deposition Prevention Structure of a Grate Type Municipal Solid Waste Incinerator Based on CFD Numerical Simulation
    ZHU Yanqun, WANG Junjie, XU Yanwei, XU Chaoqun, HE Yong, WANG Zhihua
    2023, 43(4): 483-490. https://doi.org/10.19805/j.cnki.jcspe.2023.04.013
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    To solve the problem of ash deposition in the rear arch area of the waste incinerator, three transformation cases for a 300 t/d grate waste incinerator were employed to optimize the furnace structure. Thermal simulation was carried out on the combustion process in the furnace, the viscosity-temperature characteristics of the ash deposition sample were measured by a high-temperature viscometer. Based on the ash particle deposition model, the impact and adhesion behavior of ash particles were quantitatively observed. Results show that case C is the optimal one. Compared with the original furnace, the uniformity of the flow field of case C is enhanced greatly, and the high-temperature phenomenon in the rear arch area is disappeared. Among the three cases, the collision frequency of ash particles within the back arch for case C is the lowest one, which was 6.88% lower than the original furnace. Furthermore, the adhesion ratio of ash particles is the lowest one under case C, and only 0.08% of the ash particles adhere to the wall with a probability of 13.5% at the temperature of 1 425-1 433 K.
  • Green Energy and Low-carbon Technology
    Numerical Simulation on Semi-dry Deacidification of Flue Gas for Waste Incineration Power Plants
    LI Hengfan, LI Yulong, ZHENG Zipan, JIAO Shiquan, HAN Zhonghe
    2023, 43(4): 491-498. https://doi.org/10.19805/j.cnki.jcspe.2023.04.014
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    Taking the tail flue of a waste incineration power plant as an object, the heat and mass transfer model and chemical reaction model in the process of deacidification were established based on CPFD method, and the effects of stoichiometric ratio (SR), flue gas temperature and velocity, slurry particle size and concentration and HCl concentration on deacidification efficiency were analyzed. Results show that the semi-dry flue gas deacidification of waste power plant can greatly reduce the concentration of acid gas in flue gas. The deacidification efficiency increases with the rise of SR gradually, and the dechlorination efficiency is much higher than the desulfurization efficiency. When SR is same, with the increase of flue gas velocity, the dechlorination efficiency is almost unchanged, while the desulfurization efficiency decreases. The increase of flue gas temperature, slurry concentration and the decrease of HCl concentration will reduce deacidification efficiency. The deacidification efficiency first increases and then decreases with the increase of slurry particle size. When the slurry particle size is 50 μm, the desulfurization efficiency is the largest, and when the slurry particle size is 80 μm, the dechlorination efficiency is the largest.
  • Green Energy and Low-carbon Technology
    Enhanced Photocatalytic Performance of Oxygen Vacancy BiOIO3 Based on Density Functional Theory
    LING Xiaoding, LIU Yulin, LING Yang, WU Jiang
    2023, 43(4): 499-504. https://doi.org/10.19805/j.cnki.jcspe.2023.04.015
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    Although bismuth oxide iodate (BiOIO3) has strong oxidizing property, its large band gap and small optical response range limit the development of heavy metals controlin the flue gas from the coal-fired power plants. The effect of oxygen vacancy at different positions on the photocatalytic activity of BiOIO3 was calculated using the first principle based on density functional theory (DFT). Its structural feature, band structure, electronic density of states and absorption spectrum were analyzed. Results show that the forbidden band width of the crystal becomes narrower after the construction of oxygen vacancies, and the electrons in the valence band can jump to the conduction band by absorbing less energy after the introduction of impurity energy levels as a bridge for electron jumping. Compared with pure BiOIO3, the absorption coefficients of the crystalline materials with oxygen vacancies in the visible and UV regions are significantly improved, and the photocatalytic activity is significantly enhanced.
    • Integrated Energy System
  • Integrated Energy System
    Analysis of a New Cold End Waste Heat Utilization Heating System Based on Exergy
    XIAO Zhuonan, HUO Liwei, ZHANG Rong, LI Ke, HE Lijuan
    2023, 43(4): 505-510. https://doi.org/10.19805/j.cnki.jcspe.2023.04.016
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    Taking a 315 MW subcritical unit as an object, a new cold end waste heat utilization system was designed. Based on the laws of thermodynamics and exergic analysis theory, its thermal performance was analyzed and compared with other heating methods, such as steam extraction heating, high back pressure heating and absorption heat pump heating. Results show that when the new system is running, the temperature and flow of the supply and return water are guaranteed to be constant, with the increase of back pressure, the thermal performance of the unit first increases and then decreases. The best back pressure is 23 kPa. Under certain conditions, with the increase of water supply temperature, the new system has obvious advantages compared with extraction steam heating, high back pressure heating and absorption heat pump heating. And the higher the water temperature, the more obvious the advantage of the new system. However, it is not suitable for the condition of low water supply temperature. When the return water temperature is 50 ℃, the minimum water supply temperature can only reach 78 ℃.