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    Boiler Technology
  • Boiler Technology
    Study on Combustion Stability of a 1 000 MW Swirl-opposed Boiler with Blending Coal Under Wide Load
    MA Dafu, HE Xiang, ZHANG Shouyu, ZHAO Xu, CHANG Ming
    2021, 41(12): 1019-1026. https://doi.org/10.19805/j.cnki.jcspe.2021.12.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of combustion instability in the furnace of a 1 000 MW swirl-opposed boiler under different loads, coal quality and combustion characteristics of the market coal, mixed coal, Xiangshan coal, Jin coal, peat and Fengjiachuan coal were analyzed. The characteristics of pulverized coal and combustion stability under high and low loads were studied. Results show that the main reason for the weak fire detection signals under the load of 700-1 000 MW is the lack of air in the lower burner which burns high volatile coal. The fire detection signal is obviously enhanced and the carbon content of fly ash is reduced by increasing the outer secondary damper opening. The combustion instability under the load of 400-520 MW is due to the poor quality of coal, the low heat load in the furnace section and small angle of burner expansion cone. The combustion stability can be obviously enhanced after the optimization of pulverizing system and air-flue gas system.
  • Boiler Technology
    Effects of Air Distribution on Carbon Emission Characteristics of a Tangentially Fired Boiler
    FAN Baotian, YAN Zhenrong, WANG Li, WANG Weiguo, NI Lingying
    2021, 41(12): 1027-1032. https://doi.org/10.19805/j.cnki.jcspe.2021.12.002
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    A 330 MW tangential coal-fired boiler was numerically simulated. By adjusting the air distribution, the effects of the flow, combustion, flue gas temperature and component concentration on carbon emission were analyzed, and the simulation results were compared with the experimental data. Results show that with the increase of the wind speed, the excess air coefficient increases, the temperature in the burner area gradually increases, and the temperature in the upper part of the burner and the horizontal flue region gradually decreases, indicating that the wind speed reduces the flue gas temperature at the furnace outlet. With the increase of wind speed, the CO2 and CO volume fraction at the outlet of the furnace will decrease, but the oxygen volume fraction at the outlet of the furnace under condition 3 is higher, with an average of 2.19%.
  • Boiler Technology
    Research on Gas-Solid Two-phase Flow Characteristics of Double-adjustable Pulverized Coal Distributors in Power Station Boilers
    XUE Feiyu, HAN Jianmin, LIANG Shuangyin
    2021, 41(12): 1033-1039,1108. https://doi.org/10.19805/j.cnki.jcspe.2021.12.003
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Considering the effects of the flow uniformity of the primary air and powder in the pulverizing system directly on the safety and economy of the boiler, a double adjustable pulverized coal distributor was proposed. Tapered valves were used to separate the two-phase flow of air and powder into a dense and dilute phase flow, a fan valve with an adjustable opening was used to adjust the flow respectively. Finally, the thick and thin fluids were mixed evenly, and the influence of the internal structure on the distribution of the outlet pressure drop of the distributor was calculated. Results show that the suitable range of annular taper angle is 65°-75°, and the height proportion should not exceed 60%. The air-powder separation process has a good separation effect on coal particles with particle size larger than 50 μm. The deviation of the dilute phase flow valve on the maximum outlet wind speed of a single pipe is -28.63%, which of the dense phase flow valve on the maximum powder volume is -32.61%.The distributor has great independence in controlling the wind and powder, which can significantly improve the uniformity and adjustment flexibility of the air powder system.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Experimental Study on Film Cooling Characteristics of Multi-row Holes on Turbine Blade Surface
    HE Lei, CHEN Dawei, ZHANG Yi, WANG Haifeng, LIU Zhao, ZHU Xiaocheng, DU Zhaohui
    2021, 41(12): 1040-1044,1068. https://doi.org/10.19805/j.cnki.jcspe.2021.12.004
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Film cooling characteristics of the gas turbine blade were studied on the linear-cascade film cooling test rig. The film cooling effectiveness and heat transfer coefficient of a turbine blade with multi-row fan-shaped film holes were measured by infrared imaging technology. The distribution of film cooling effectiveness and heat transfer coefficient of the pressure surface and suction surface of the blade under different blowing ratios were analyzed. Results show that with the increase of the blowing ratio, the film cooling effectiveness in downstream of most of the holes on the pressure surface increases, the film cooling effectiveness of the first rows film holes on the suction surface decreases, and the film cooling effectiveness of the second and the third rows film holes on the suction surface increase first and then decrease with increasing blowing ratios. Meanwhile, the film cooling effectiveness in the downstream of the fourth rows holes on the suction surface increases. When the blowing ratio is large, the film outflow makes the heat transfer coefficient of most areas of the blade surface increase slightly compared with that without film.
  • Steam Turbine and Gas Turbine
    Study on Film Cooling and Flow Characteristics of Conical Combined Holes with Short Aspect Ratio and Heart Shaped Holes
    YE Xiu, WU Meiping, MIAO Xiaojin, LU Peipei
    2021, 41(12): 1045-1053. https://doi.org/10.19805/j.cnki.jcspe.2021.12.005
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the film cooling characteristics of thin-double-walled blades, a conical combined hole was constructed based on the conical hole, and the structure of the heart shaped hole was optimized, so as to study cooling and flow characteristics of two types of film holes at different blowing ratios, as well as the effects of vortex structure in film hole on jet vortex structure. Results show that the development of jet at the inlet of filming hole has decisive effect on cooling and flow characteristics of the outlet jet. The jet vortex structure downstream the film hole depends on blowing ratio, film cooling effectiveness of both heart shaped hole and conical combined hole reaches the maximum at the blowing ratio of 1.0. The central area of downstream the heart shaped hole shows as a typical inverse renal vortex structure. When the blowing ratio is 1.0, film cooling efficiency of the heart shaped hole is about 8% higher than that of the conical combined hole.
  • Steam Turbine and Gas Turbine
    Effects of Air-flux-ratio on Combustion Performance of Micro Gas Turbine Combustor
    HUANG Yang, WANG Wenhuan, CHI Zhiwei, PAN Weiguo
    2021, 41(12): 1054-1060,1102. https://doi.org/10.19805/j.cnki.jcspe.2021.12.006
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    Taking the micro gas turbine combustor with premixed combustion mode of fuel and air as the object, a model was established for the combustor chamber based on design parameters, the process of turbulent flow and chemical reaction during combustion for the premixed fuel in the combustor was simulated under different working conditions, so as to obtain reacting flow field and combustion temperature distribution in the combustor, as well as the emission of pollutants in outlet flue gas. Results show that at the total excess air coefficient of 3.01, as the inlet equivalence ratio of hydrocyclone and the combustion-supporting air ratio increase, front temperature of the premixed flame increases, and the outlet NOx mass concentration is positively correlated with the outlet temperature distribution factor.
    • Engineering Thermophysics
  • Engineering Thermophysics
    Study on Combustion Characteristics of LCV Gas in Oxy-steam Atmosphere
    LIN Richeng, YAN Xiaozhong, HE Xu, MA Qishun
    2021, 41(12): 1061-1068. https://doi.org/10.19805/j.cnki.jcspe.2021.12.007
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The combustion of blast furnace gas in Oxy-steam atmosphere was numerically simulated by Fluent software, so as to analyze the effects of water vapor volume fraction on gas combustion temperature, temperature distribution in furnace, volume fraction of flue gas components, NOx volume fraction and soot volume fraction. Results show that when burning in Oxy-steam atmosphere, the maximum combustion temperature of blast furnace gas decreases from 1 350 K to 1 290 K due to the fact that specific heat capacity of water vapor is higher than that of N2 and there exists a large number of OH and H functional groups. Compared with the combustion in O2/N2 atmosphere, temperature distribution in the furnace is more uniform and CO combustion is more complete in Oxy-steam atmosphere, furthermore, NOx volume fraction and soot volume fraction at the furnace outlet decrease rapidly. With the increase of steam volume fraction, the flue gas velocity at the furnace outlet decreases from 0.55 m/s to 0.505 m/s. Compared with the combustion in O2/N2 atmosphere, the mole fraction of H2 and CH4 at the furnace outlet increases slightly in Oxy-steam atmosphere.
  • Engineering Thermophysics
    Study on Effects of Diluent Gas on Flame Flickering and Its Nonlinear Characteristics
    JI Mingdong, PAN Wenxuan, YANG Mo
    2021, 41(12): 1069-1074,1089. https://doi.org/10.19805/j.cnki.jcspe.2021.12.008
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to study the influence of diluent gas on instability of flame flickering, the combustion of flame in coaxial jet burner was simulated by Fluent software. As diluent gas, the influence of CO2 and N2 on flame flickering was studied, so as to analyze the nonlinear characteristics of flame flickering. Results show that the maximum axial flame temperature decreases with the increase of dilution ratio, and the oscillation of the flame also weakens. Compared with N2, CO2 can suppress flame flickering more easily. With the increase of dilution ratio, the peak flicker frequency of the flame increases gradually, and the flow and heat transfer of the combustion system would also change from periodic oscillation to chaos.
  • Engineering Thermophysics
    Three-dimensional Flow Characteristics in the Tube Bundle Area of Large Scale Low-temperature and Multi-effects Falling-film Evaporator
    ZHANG Yousen
    2021, 41(12): 1075-1080. https://doi.org/10.19805/j.cnki.jcspe.2021.12.009
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on triangle configuration of tube bundles in the low-temperature and multi-effects desalination (LT-MED) evaporator, a porous media model was adopted for three-dimensional numerical simulation of a large-scale evaporator with multiple tube bundles. Results show that a stratified flow of steam in the tube bundles zone occurs with low velocity and high pressure in its top and bottom regions. Demister arrangement influences the flow of secondary steam. The steam velocity near the bundles zone of demister becomes larger obviously, which increases along the tube length and reaches a maximum value in the end of the tubes. Along the tube row, the steam velocity increases firstly and then decreases, while along the tube column, it turns to opposite trend. The secondary steam velocity along the axial flow channel increases gradually and reaches a maximum value at its outlet. The steam velocity decreases when the steam flows out of the axial flow channel, and then a big vortex forms at the upper and lower parts of evaporator exit. The resistance loss of steam in the evaporator mainly occurs in the axial channels with larger velocity gradient, and small resistance loss in the tube bundles zone is observed.
    • New Energy
  • New Energy
    Numerical Study on the Influence of Toothed Gurney Flap and Span on the Aerodynamic Performance of an Axial Fan
    ZHENG Nan, YE Xuemin, HU Jiami, LI Chunxi
    2021, 41(12): 1081-1089. https://doi.org/10.19805/j.cnki.jcspe.2021.12.010
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on large eddy simulation, a numerical study of a variable-pitch axial fan with different spans of toothed Gurney flap (TGF) was carried out. The effects of the TGF and span on fan performance, aerodynamic noise and static pressure distribution were explored, and the internal relationship between noise and vortex structure distribution was analyzed. Results show that the total pressure of the fan can be obviously increased with the TGF, its increase amplitude is proportional to the flap span, and the total pressure can achieve a rise of 1 409 Pa when the flap span is 0.9. The noise reduction of the fan with the TGF increases with the decrease of the flap span, when the latter is 0.7, the former reaches 18.33 dB. The TGF has a series of effects including weakening the wake strength of the blade, improving the root bubble vortex size, forming a longer tubular vortex at the top of the flap, and damping the interaction between the wake vortex and the tip leakage flow. The smaller the flap span, the more significant the effect of improvement and noise reduction. When the flap span is 0.9, the TGF has the best comprehensive performance in improving the total pressure, widening the high efficiency area and reducing noise, and it also has a notable improvement in the total pressure rise and the efficiency of large flow rate side under variable installation angles.
  • New Energy
    Aerodynamic Design and Performance Test of High Flow Centrifugal Air Compressor for Hydrogen Fuel Cell
    MA Mingjun, ZHANG Chengyi
    2021, 41(12): 1090-1095. https://doi.org/10.19805/j.cnki.jcspe.2021.12.011
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the demand of 100 kW hydrogen fuel cell stack, the aerodynamic design of two-stage series centrifugal air compressor was carried out. The pressure ratio distribution of the two-stage impellers was determined according to the axial force, specific speed and impeller size. The flow loss at the inlet and outlet of the impeller was reduced by the middle loading profile design. The aerodynamic load at the leading edge of the high-pressure impellers and the tip leakage loss were reduced by the forward blade design. The three-dimensional flow numerical simulation analysis of the air compressor was carried out. Results show that the internal flow of the air compressor is good. Under the design speed and the mass flow rate of 130 g/s, the overall pressure ratio reaches 2.82 and the aerodynamic efficiency reaches 77.5%. The performance can meet the application requirements of 100 kW hydrogen fuel cell stack.
    • Material Research
  • Material Research
    Study on Microstructure and Hardness of T92/Super304H Dissimilar Steel Welded Joint
    XIE Ruiwen, MA Xingchi, YUAN Binxia, SUN Yongjun, SHEN Li
    2021, 41(12): 1096-1102. https://doi.org/10.19805/j.cnki.jcspe.2021.12.012
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    Microstructure and hardness of T92/Super304H dissimilar steel welded joint were studied by means of optical microscope, scanning electron microscope, digital micro-hardness tester and energy dispersive X-ray spectrometer, and the mechanical properties of welded joints were analyzed. Results show that the Super304H heat affected zone (HAZ) of welded joint has coarse equiaxed austenite grains, and the austenite grains and lath martensite in T92 fusion zone are fine. The hardness of T92 HAZ is the highest because of the welding thermal cycle during welding. Under high stress loading, the fracture position of high temperature tensile specimen occurs in T92 HAZ, and the dimple fracture is dominated by plastic transgranular fracture.
    • Nuclear Technology
  • Nuclear Technology
    Numerical Simulation of Cavitation and Structure Optimization of a Control Valve Based on CFX
    LI Liancui, WANG Zhoujie, ZHANG Han, GONG Shengquan, LIU Chunling
    2021, 41(12): 1103-1108. https://doi.org/10.19805/j.cnki.jcspe.2021.12.013
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    In order to reduce the cavitation damage of a control valve in a nuclear power plant under maximum operating condition, multiphase flow model and cavitation model were used to simulate the cavitation of the control valve before and after optimization based on CFX software. And the influence of different structures in the control valve on cavitation distribution and degree was analyzed. Results show that the sealing line of the control valve spool, as the key part, is vulnerable to be damaged by cavitation. Part of cavitation near the sealing line of the control valve spool can be transferred by the optimized structure, and thus the degree of cavitation near the sealing line is reduced effectively, which is helpful to protect the integrity of the sealing line.