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    Boiler Technology
  • Boiler Technology
    Calculation and Analysis of Depth Peak Regulation Performance of a Coal-fired Power Plant
    ZHOU Xihong, BI Lingfeng, YANG Haoyu, YANG Dong, ZHU Chao, WU Pengju
    2021, 41(10): 809-817. https://doi.org/10.19805/j.cnki.jcspe.2021.10.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the deep peak regulation capacity of a coal-fired power plant, the corresponding mathematical models of low load stable combustion, thermal-hydraulic circulation, wide-load denitrification, low-temperature corrosion of air preheater and auxiliary safety were established, and the calculation program was compiled based on Fortran language. In the low load stable combustion model, D-S evidence theory was used to judge the combustion stability of the boiler during deep peak regulation. The thermal-hydraulic circulation model used the nonlinear flow network system method to calculate key parameters of water cooling wall. In the wide-load denitrification model, the relationship between the inlet flue gas temperature of selective catalytic reduction reactor and the lowest operating temperature of catalyst was compared to determine whether the boiler denitrification was normally. The corrosion degree of air preheater was determined by comparing the relationship between acid dew point and the lowest wall temperature in the low-temperature corrosion model. The matching of the required pressure head and the characteristic curve of the fan was analyzed to judge the operation stability in the auxiliary safety model. Results show that the thermal-hydraulic circulation of 660 MW boiler in Shaanxi Qinling (Qinhua) Power Generation Co., Ltd. is safe under 20% boiler maximum continuous rating load, and the primary fan runs in the stable operating area. The program can be used in the engineering practice and provide guidance for the boiler deep peak regulation.
  • Boiler Technology
    Dynamic Simulation Research on Large Circulating Fluidized Bed Boiler Considering Transverse Mass Transfer
    LI Zheng, WEN Chenyang, XU Zhaofeng, XUE Yali, LIU Pei
    2021, 41(10): 818-823. https://doi.org/10.19805/j.cnki.jcspe.2021.10.002
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    In order to study the phenomenon of the uneven lateral distribution of operating parameters in a large circulating fluidized bed (CFB) boiler, on the basis of the original one-dimensional model, a quasi-two-dimensional compartment model was established, in which the furnace was divided into four parallel loops along the width direction while heat & mass transfer and combustion in the furnace and lateral mass transfer among parallel loops were taken into account. Besides, the compound pressure drop model of flue air system including fan, air distributor, furnace and separator was also set up. Moreover, based on the dynamic simulation of a 660 MW ultra supercritical CFB boiler, the lateral fluctuation of bed pressure under specific working conditions was mainly studied while the transverse mass transfer in the process of bed pressure fluctuation was analyzed. Results show that the lateral distribution of operating parameters in the furnace can be reflected via the quasi-two-dimensional compartment model. The comprehensive effect of transverse diffusion and convection of materials in the furnace is the reason for the periodic fluctuation of bed pressure.
  • Boiler Technology
    Numerical Simulation of Combustion Process in a Gas-fired Boiler with Sewage Sludge Gasified Gas
    ZHANG Zhenrong, HUANG Yaji, WANG Xinyu, ZHU Zhicheng, LIU Yang, YANG Xiaoyu, TIAN Xinqi
    2021, 41(10): 824-832. https://doi.org/10.19805/j.cnki.jcspe.2021.10.003
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    Flow and combustion process of sewage sludge gasified gas under one design condition and eight reference conditions in the furnace of a gas-fired boiler were simulated by Ansys Fluent soft. Results show that the gas in the furnace rotates and rises while burning severely. The maximum temperature in bottom nozzle section under design condition can reach 1 200 K. Air and gas inlet velocities have significant influence on the combustion temperature and the concentration of oxygen and carbon dioxide in the furnace. The average temperature in bottom nozzle section reaches 1 300 K and the average oxygen concentration decreases significantly with the increase of gas inlet velocity. The combustion reaction is intensified by increasing the combustible components. With the increase of carbon monoxide concentration up to 18% in the gas, the average temperature in bottom nozzle section can reach 1 400 K, but it has little influence on the average oxygen and carbon dioxide concentration at the most furnace heights.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Aerodynamic Performance and Biomimetic Optimization of Low-pressure Last Stage Blade of Steam Turbine
    HAN An, JIANG Wei, WU Fan, WANG Chun, XIE Danmei
    2021, 41(10): 833-841. https://doi.org/10.19805/j.cnki.jcspe.2021.10.004
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    A numerical simulation method was used to analyze the aerodynamic performance of flow separation in the low-pressure last stage blade of the thermal turbine under low volume flow conditions. In order to improve the work capacity of the steam turbine under the condition of low volume flow, the structure of humpback whale head was applied to the back pressure surface of the last stage rotor blade design optimization, and the axial torque of the last stage rotor blade of the original blade and different improved blade types were compared based on orthogonal analysis. Results show that biomimetic structure has a positive effect on the increasement of the axial torque under the condition of small volume flow. Based on orthogonal analysis, the torque of biomimetic blades with tubercles of different parameters are calculated and the optimal structure has been achieved, which can increase the axial torque by 26.6% under relative volume flow=0.358 0.
  • Steam Turbine and Gas Turbine
    Flow Analysis and Profile Optimization of Transonic Blade Tip Section
    LIU Yingchao, CHEN Liu, DAI Ren, YANG Qiguo
    2021, 41(10): 842-848. https://doi.org/10.19805/j.cnki.jcspe.2021.10.005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The flow analysis software CFX was used to simulate the transonic flow in the last stage blade tip section of a steam turbine, and the shock wave characteristics and flow loss mechanism in the cascade were analyzed. The third-order Bezier curve was adopted to shape the camber line of the blade profile. A combination of the second-order and third-order Bezier curves was used to prescribe the thickness distribution along the blade chord. Kriging surrogate model was combined to optimize the blade profile and improve the aerodynamic performance. Results show that the aerodynamic loss of the tip section of last stage rotor blade is mainly related to the shock intensity and its reflection position. After the blade profile is optimized, shock intensity in the cascade is weakened, and shock loss is reduced by about 32% compared to the original blade profile. At the same time, the impact of the shock wave on the boundary layer is weakened, and the boundary layer loss is reduced by about 17%. The total pressure loss of the optimized blade profile is reduced by 24%, and the aerodynamic performance is significantly improved.
  • Steam Turbine and Gas Turbine
    Numerical Study on Thermo-Fluid-Solid Coupling Heat Transfer Performance of Moist Gas Turbine Blades
    FU Yangchun, LI Jianwu, LIAO Guie, ZHANG Zhiwei, LI Liang
    2021, 41(10): 849-858. https://doi.org/10.19805/j.cnki.jcspe.2021.10.006
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking a C3X blade as an example,a thermo-fluid-solid coupling simulation was carried out to evaluate the moist gas heat transfer performance and the moist air cooling effect upon turbine blades. The influence of the moist gas humidity ratio on turbine blade surface temperature and heat transfer coefficient were investigated, and cooling performances between the dry air and the moist air were compared and analyzed. Heat transfer coefficient dimensionless relation of turbine blade was given,which provide reference for optimization of humidified turbine and design of cooling structure. Results show that the moist gas humidity ratio has no distinct influence on flow characteristics of turbine blade. When the humidity ratio increases from 0 g/kg to 150 g/kg, heat transfer coefficient of turbine blade surface increase by 10% at inlet temperature of 1 473 K and the increments are enlarged with the rise of inlet temperature. Besides, the turbine blade wall temperature increases by 10 K. Compared with dry air, it can be achieved lower blade wall temperature and higher cooling efficiency while using moist air as the cooling medium, and the moist air cooling efficiency increases with the rise of moist air humid ratio.
    • Monitoring and Measurement
  • Monitoring and Measurement
    Study on Abnormal Data Recognition of Wind Turbines Based on Adaptive DBSCAN Algorithm
    LEI Meng, GUO Peng, LIU Bosong
    2021, 41(10): 859-865. https://doi.org/10.19805/j.cnki.jcspe.2021.10.007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to effectively identify and eliminate the actual abnormal data of wind turbines, an adaptive density clustering (density-based spatial clustering of applications with noise, DBSCAN) abnormal data recognition algorithm based on sub-power interval was proposed by analyzing the abnormal wind speed-power data of wind turbines. The key parameters such as radius (ε) and neighborhood radius threshold (Z) in DBSCAN clustering were adaptively and optimally selected by using unlabeled clustering profile coefficients, and the abnormal data of experimental units were identified by the algorithm. Results show that the algorithm avoids the errors caused by human subjective setting and can effectively identify abnormal data of wind turbines.
  • Monitoring and Measurement
    On-line Measurement of Size and Concentration for Droplet Particles in Desulfurization Flue Gas by Digital Holographic Microscopy
    WENG Jianming, JIN Jun, LIN Zhiming, SHEN Li, WANG Zhigang, WU Yingchun, WU Xuecheng, SHI Pengfei
    2021, 41(10): 866-870. https://doi.org/10.19805/j.cnki.jcspe.2021.10.008
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    The on-line measurement of flue gas droplet concentration was carried out by using digital holographic microscopy (DMH) measurement technology. The droplet generation system and DMH measurement system based on ultrasonic atomization were designed and built, and the droplet field of ultrasonic atomization was measured by DMH measurement system. Results show that the measurement error of DMH measurement system is about 4.5%, which shows good accuracy. Under the atomization quantitiy of 10%, 30% and 50%, the droplet sizes corresponding to the probability peak are 2.49 μm, 2.58 μm and 2.56 μm respectively, which are basically the same. With the increase of atomization quantitiy, the probability distribution curve of droplet mass concentration gradually becomes normal distribution.
    • Engineering Thermophysics
  • Engineering Thermophysics
    Analysis of Solid-Liquid Phase Transition and Nonlinear Characteristics of Paraffin in Square Cavity
    ZHANG Zheng, YANG Mo, LI Yirong
    2021, 41(10): 871-876. https://doi.org/10.19805/j.cnki.jcspe.2021.10.009
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    Phase transformation characteristics of paraffin in solid phase and flow characteristics of paraffin in liquid phase were studied by using the Solidification/Melting model based on enthalpy method. Results show that under the same boundary conditions, the melting of paraffin in square cavity can be characterized by multiple solutions, and the melting rate is also different. In liquid phase region, the flow state of natural convection of paraffin heated at the bottom of square cavity is affected by Ra. When Ra=3.5×104, the phase space trajectory is shown as a fixed point, which is shown as limit cycle and chaos at Ra of 2.19×105 and 2.3×106, respectively. Final state of the flow field in the liquid phase region can be controlled by setting the temperature of the upper and lower walls constant and changing Ra by controlling the height of the physical model.
    • New Energy
  • New Energy
    Numerical Study on the Influence of Shear Inflow on Wind Turbine Wakes
    WANG Tianfan, SHI Liuliu
    2021, 41(10): 877-882. https://doi.org/10.19805/j.cnki.jcspe.2021.10.010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the influence of shear index on wake characteristics of the wind turbine, taking NREL Phase VI wind turbine as the research object, the steady numerical simulation of wake flow field for wind turbine at different shear indexes was carried out by using SST k-ω turbulence model. Moreover, the effects of vortex structure in wind turbine wake on following flow parameters were investigated at different shear inflow conditions, such as velocity and turbulent kinetic energy. Results show that the wake flow field becomes asymmetric under the shear inflow condition, and the wakes deviate away from the wall. With the increase of shear index, the strength of the central vortex above the hub increases, while the strength of the central vortex below the hub decreases. A narrow high-speed strip can be found in the wake due to the fact that the lower part fluid is heavily sucked into the upper shear layer. The turbulent kinetic energy of the wake flow field would be increased and the recovery of the wake velocity would slow down due to the non-asymmetry of the central vortex.
  • New Energy
    Research on Lift Increase and Drag Reduction of S809 Airfoil Based on Suction-Blow Combined Jet
    LUO Shuai, MIAO Weipao, LIU Qingsong, LI Chun
    2021, 41(10): 883-891. https://doi.org/10.19805/j.cnki.jcspe.2021.10.011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The Suction-Blow Combined Jet (SBCJ) mode was proposed to improve the aerodynamic characteristics of the wind wing. Based on the S809 airfoil, the control effect of SBCJ under different attack angles, jet momentum coefficients and opening positions was studied, and its control mechanism and influence rule was analysed. Results show that SBCJ can remove the low-momentum fluid on the suction surface of the airfoil and change the trailing edge Kutta conditions, which can significantly increase the pressure difference on both sides of the airfoil and finally improve the aerodynamic performance of the airfoil. When the jet momentum coefficient is small, the lift force of the airfoil increases significantly, while the correction resistance and the flow separation decrease. When the suction hole is 0.15c from the leading edge, the blow hole is 0.2c from the trailing edge and the attack angle is 10°, the modified lift-drag ratio of the airfoil increases the most.
    • Nuclear Technology
  • Nuclear Technology
    Experimental Investigation on Pressure Oscillation Characteristics of Condensation Induced Water Hammer in Passive Residual Heat Removal Pipeline
    LIU Wenbing, ZHANG Zhuohua, CAI Haigang, CHONG Daotong, ZHAO Quanbin, YAN Junjie
    2021, 41(10): 892-897. https://doi.org/10.19805/j.cnki.jcspe.2021.10.012
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the visualization experimental system of the passive residual heat removal pipe,the condensation induced water hammer (CIWH) in the passive residual heat removal pipeline was experimentally studyed through the high-speed camera and fast dynamic pressure transducers. The coupling relationship between steam-water phase interface evolution and pressure oscillation during the CIWH process was investigated. And the variation laws of the CIWH's occurrence process, position, and number were also analyzed. Results show that the CIWH would experience four stages such as stratified flow, wavy flow, slug flow and steam bubble collapse. The pressure in the pipe is stable during stratified flow and wavy flow, which is negative during slug flow.And a huge pressure pulse is generated when steam bubble collapses. The CIWH position will move towards to the pipe outlet and the occurrence number will decrease with the rise of heat flux density and water temperature.
  • Nuclear Technology
    Study on Energy Conversion of Hydraulic Components During Idle Process of Coolant Pump in Nuclear Power Station
    YE Daoxing, LIU Anlin, LUO Yimin, CHEN Junlin
    2021, 41(10): 898-904. https://doi.org/10.19805/j.cnki.jcspe.2021.10.013
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    In order to explore the energy conversion characteristics of the hydraulic components in the coolant pump after entering idling state, numerical method was used to study the idling state of the coolant pump. Results show that with the increase of idle time, the head loss of each hydraulic flow component decrease to less than 50% after 10 s. During the idling process, the dynamic pressure head of the inlet section decrease sharply from 6.8 m to 0 m, and the static pressure head increase from -7 m to 0 m after 140 s. At the beginning of idling, the static pressure energy at the outlet of the impeller decrease slowly, which increase rapidly at the inlet. With the increase of idle time, the static pressure head of impeller decrease faster than the dynamic pressure head, the dynamic pressure energy of guide vane and impeller change in a contrary way. The dynamic pressure energy at the inlet and outlet of the volute decrease rapidly with the increase of idle time, and the static pressure energy at the inlet of the volute decrease rapidly from idling. At the beginning of idling, the dynamic pressure energy above 24.33 m is mainly distributed at the outlet of impeller, guide vane inlet and the outlet of volute; When t=110 s, the dynamic pressure energy in most areas is mainly below 12.17 m; When t=200 s, the dynamic pressure energy is mainly distributed in 0-6.08m. The distribution area of large static pressure energy in the volute decrease gradually.