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    Boiler Technology
  • Boiler Technology
    SOFA Air Distribution Optimization of a Low Heat Value Lignite Coal-fired Boiler Based on Numerical Simulation
    JI Mingbin
    2020, 40(9): 693-700. https://doi.org/10.19805/j.cnki.jcspe.2020.09.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problems of high CO emission concentration at furnace outlet and coking at flue gas exhaust outlet existing in a 670 MW octagonal corner tangentially-fired tower boiler burning low calorific value lignite, numerical simulations and experimental tests were conducted to study the effects of the following factors on the in-furnace temperature field, and the O2, NOx and CO concentration distribution, such as the vertical swing angle of SOFA, the SOFA volume and the SOFA speed, etc. Results show that the increase of SOFA air velocity can effectively reduce the flue gas temperature and CO concentration at furnace outlet. Compared with case 1, the outlet CO concentration of the furnace in case 6 has been reduced from 0.291 2% to 0.025 7%, with a reduction of flue gas temperature at furnace outlet by 43 K, a reduction of exhaust gas temperature by 6 K, an increase of boiler efficiency by 0.63%, and a reduction of standard coal consumption by 2 g/(kW·h), while the NOx emission concentration basically keeps unchanged at furnace outlet.
  • Boiler Technology
    Quantitative Valuation of Coal-fired Units Under Deep Peak Regulation Conditions
    WANG Shudong, LÜ Weizhi
    2020, 40(9): 701-706. https://doi.org/10.19805/j.cnki.jcspe.2020.09.002
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    To quantify the benefits of coal-fired units under deep peak regulation conditions, the coal consumption rate and cost increment of power supply were analyzed at different loads for a 300 MW subcritical unit, a 600 MW subcritical unit and a 600 MW supercritical unit. Considering the environmental and economic benefits of the coal-fired units, a dispatching model was established to quantitatively study the environmental and economic benefits under deep peak regulation conditions via model calculation. Results show that with the decrease of unit load, both the coal consumption and unit cost of power supply increase for the coal-fired units. The deeper the participation of coal-fired units is in peak regulation, the higher the power generation cost would be. High capacity and high steam parameters would result in high unit cost of power supply for the coal-fired units.
  • Boiler Technology
    Effects of High Chlorine Oil-based Cuttings on the Operation of a Boiler
    ZHANG Qian
    2020, 40(9): 707-712. https://doi.org/10.19805/j.cnki.jcspe.2020.09.003
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    To study the effects of high content of chlorine in oil-based cuttings on the operation of a boiler and related systems, the HCl concentration in flue gas was calculated under different blending ratios of oil-based cuttings, while the corrosion rate of HCl in flue gas over high and low temperature heating surfaces were computed respectively by weight gain method and weight loss method. In addition, the chlorine balance in the desulfurization system was analyzed. Results show that the chlorine content introduced by oil-based cuttings may accelerate the corrosion of high and low temperature heating surfaces. Compared with the pure coal combustion condition and in the case of blending ratio of 5.9%, the HCl concentration in flue gas would be increased by 9 times, with an increase in corrosion rate of HCl to T91 metal by 56%, and that to 15CrMoG by 12.5%; the dew point of hydrochloric acid would be increased by 1.7 K; the amount of desulfurization wastewater would be increased from 0.91 t/h to 6.8 t/h, showing a six-fold increase over pure coal combustion condition. It is difficult to maintain chlorine balance in the desulfurization system. Therefore, the proportion of oil-based cuttings must be controlled to ensure normal operation for the boiler and the desulfurization system.
    • Monitoring and Measurement
  • Monitoring and Measurement
    Combustion Condition Monitoring Based on Flame Imaging and Convolutional Sparse Auto Encoder
    WANG Yuwei, TIAN Hongwei, QIN Yongxin, HAN Zhezhe, XU Chuanlong
    2020, 40(9): 713-719. https://doi.org/10.19805/j.cnki.jcspe.2020.09.004
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    A method was proposed for the monitoring of combustion condition based on flame imaging and convolutional sparse auto encoder (CSAE), which adopts CSAE network with deep architectures to extract the essential features of flame images, and then to input the essential features into a Soft-max classifier for combustion condition identification. The feasibility of the method was verified by the flame images obtained from a 300 MW power plant boiler. Results demonstrate that the proposed CSAE-Soft-max model achieves an identification accuracy of 98.9%, proving the method to be available.
  • Monitoring and Measurement
    Rotor Fault Diagnosis Based on CERLMDAN
    TANG Guiji, LI Shucai, LU Shengyang, ZHANG Weijiang, GAO Xiang
    2020, 40(9): 720-727. https://doi.org/10.19805/j.cnki.jcspe.2020.09.005
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    To extract the fault features of a rotor more accurately, a feature extraction method was proposed based on complete ensemble robust local mean decomposition with adaptive noise (CERLMDAN). Subsequently, the CERLMDAN, the robust local mean decomposition (RLMD), and the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) were used to process the rotor unbalance and rubbing signals measured in a power plant to obtain the components of each order. Then the components were treated by Hilbert transform to obtain the instantaneous frequency of each component, following which, the type of rotor fault was diagnosed through time-frequency analysis based on the Hilbert time-frequency diagram of the signals. Results show that the method proposed has a good decomposition effect and can more accurately identify the fault type while suppressing modal aliasing.
    • Auxiliary Equipment Technology
  • Auxiliary Equipment Technology
    Difference Analysis on Calculation and Evaluation Methods in the Standards for Cooling Tower Performance Tests of Large Wet Cooling Units
    LIU Wei, ZHAO Wen
    2020, 40(9): 728-734. https://doi.org/10.19805/j.cnki.jcspe.2020.09.006
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    To find the difference in various evaluation standards and obtain optimal calculation and evaluation results, calculation formulas and evaluation methods in different standards for performance tests of cooling towers were analyzed by examples. Results show that different standards have different calculation and evaluation methods, which have a great impact on the final result and evaluation conclusion, including the methods for calculating the coefficient of heat carried by evaporation, the heat balance error, the air density, the air enthalpy, the saturated steam pressure and the number of transfer units, as well as the difference in curve fitting and reading. By referring to appropriate calculation formulas and evaluation methods in various standards, the accuracy of corresponding test results can be improved.
  • Auxiliary Equipment Technology
    Experimental Study on Noise Reduction of an Axial Flow Fan with Inclined Serrated Trailing Edge
    HUANG Qiqi, CHEN Eryun, YANG Ailing, LIU Jiacheng
    2020, 40(9): 735-741. https://doi.org/10.19805/j.cnki.jcspe.2020.09.007
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    The noise reduction structure of bionic serrated trailing edge was applied to a small axial flow fan designed on the basis of NACA65-010 blade through bending technology. The prototype fan, the traditional serrated trailing edge fan and the inclined serrated trailing edge fan were compared and analyzed through wind tunnel experiment. In the semi-anechoic chamber, the noise characteristics of above three kinds of trailing edges were measured by Brüel&Kjær hand-held sound intensity analyzer, so as to study the influence of the inclined angle on the trailing edge noise of the fan. Results show that at the rotation speed of 1 800 r/min, the inclined serrated trailing edge helps the fan to have a lower noise by 1.15~2.38 dB in the full flow range, with better noise reduction effectiveness than the traditional serrated trailing edge fan, and the optimal noise reduction effectiveness appears at the inclined angle of φ=30°, while the specific A-weighted sound level could be reduced by 1.87 dB. However, the total pressure of the fan with serrated trailing edge reduces, with a maximum drop by 8.3% under design conditions.
  • Auxiliary Equipment Technology
    Numerical Simulation on Separation Performance of a Cyclone Separator with an Expanded Volume at the Bottom
    CHEN Donglin, LI Yaqin, CHEN Xiaojian
    2020, 40(9): 742-749. https://doi.org/10.19805/j.cnki.jcspe.2020.09.008
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    To improve the separation efficiency of traditional cyclone separators, a new type of separator with an expanded volume at the bottom was proposed. The influence of the diameter of volume-expanded section on the separation performance of the separator was studied by numerical simulation, which was subsequently compared with that of a traditional separator. Results show that the bottom expanded section can effectively increase the outer vortex area and reduce the back mixing phenomenon of particles at the bottom of the separator. With rising diameter of the expanded section, the pressure drop between inlet and outlet of the separator decreases gradually under the same height of the expanded section, the separation efficiency of pulverized coal with particle diameters less than or equal to 20 μm firstly increases and then decreases, while the separation efficiency of pulverized coal with particle diameters greater than 20 μm decreases gradually. The general efficiency could reach the highest value of 90.03% when the diameter of the expanded section is 1.30D, which is 4.4% higher than that of a traditional cyclone separator.
    • Environmental Protection Technology and Equipment
  • Environmental Protection Technology and Equipment
    Experimental Study on Membrane Desorption of CO2-rich Solutions with MDEA Mixed Amine
    ZHANG Weifeng, DENG Zhaoxiong, QIU Xuefei, MA Weichun, LI Juan, WANG Qiuhua
    2020, 40(9): 750-756. https://doi.org/10.19805/j.cnki.jcspe.2020.09.009
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    To study the desorption property of two mixed solutions, with MDEA as the absorbent, and MEA and PG as the additives, membrane desorption tests were carried out on their CO2-rich solutions. Based on the desorption effects of above two adsorption solutions, the desorption rate and speed of CO2 were researched under different operation conditions. Results show that the desorption rate of MDEA+MEA is higher than that of MDEA+ PG at the same desorption time; at the same concentration of adsorption solutions, the desorption effectiveness of MDEA+PG is better. High desorption temperature and high N2 flow rate are beneficial to the increase of CO2 desorption rate, which accelerate the desorption process. The increase in flow rate of CO2-rich solutions would lead to the decrease in desorption rate of CO2. To obtain the optimal desporption performance, it is suggested taking MDEA+MEA as the absorbent, and simultaneously adopting the following process parameters:desorption temperature 50℃, flow rate of CO2-rich solution 0.89×10-3 m3/s, and N2 flow rate 150 mL/min.
  • Environmental Protection Technology and Equipment
    Study on Reaction Properties of Fe2O3/MgO Oxygen Carrier
    LIU Yulou, ZHENG Min, PU Sixu
    2020, 40(9): 757-764. https://doi.org/10.19805/j.cnki.jcspe.2020.09.010
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    Fe2O3/MgO and Fe2O3-CuO/MgO oxygen carriers (OCs) with different Fe/Mg mass ratios were prepared by impregnation method to conduct reduction and cycle experiments in a thermogravimetric analyzer, so as to study the effects of the following factors on the reduction and cycle properties of the oxygen carriers, such as the reaction temperature, Fe/Mg mass ratio and CuO active component, etc. Meanwhile, the physicochemical properties of above OCs were analyzed by H2-TPR and XRD characterization techniques. Results show that as the mass fraction of Fe2O3 increases, the reducibility of the Fe2O3/MgO OC increases, but the hydrogen consumption per unit mass of Fe2O3 drops continuously; when the mass fraction of Fe lies in 13.5%-72%, the reactivity of the Fe2O3-CuO/MgO OC would be lower than that of the Fe2O3/MgO OC. The weight loss rate of the Fe2O3/MgO OC increases with the rise of reaction temperature; as the mass ratio of Fe2O3 decreases, the reduction property of the Fe2O3/MgO OC decreases, but its cycle stability increases, which might be resulted from the increase of Mg mass fraction.
    • New Energy
  • New Energy
    Effects of Leading Edge Aerodynamic Sliding Vane on Dynamic Stall Characteristics of the Airfoil
    XIANG Bin, MIAO Weipao, LI Chun, ZHU Haitian, HAO Wenxing, DENG Yunhe
    2020, 40(9): 765-772. https://doi.org/10.19805/j.cnki.jcspe.2020.09.011
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    To suppress the dynamic stall of an airfoil, a new profile was proposed by adding an aerodynamic sliding vane at the leading edge of a NACA0012 airfoil, following which, the sliding mesh and overset mesh were used to numerically simulate the influence of the sliding vane on the aerodynamic performance of the airfoil by means of SST k-ω turbulence model. Results show that the sliding vane could effectively suppress the occurrence of dynamic stall and delay the generation of leading edge separation vortexes in the upward process. Compared with the original airfoil, the airfoil with sliding vane could significantly decrease the drag coefficient and increase the lift-drag ratio in the upward process. Whereas in the downward process, the lift coefficient of the airfoil with sliding vane increases obviously, while the hysteresis effect weakens. The extension height of the sliding vane is closely related to the lift-drag ratio of the airfoil.
    • Nuclear Technology
  • Nuclear Technology
    Effect of Liquid Film Parameters on Dynamic and Static Performance of a Water-lubricated Guide Bearing for Reactor Coolant Pump
    HU Ping, LAI Xide, YUE Qingwen, CHENG Hai, TANG Lixin
    2020, 40(9): 773-780. https://doi.org/10.19805/j.cnki.jcspe.2020.09.012
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    To optimize the geometric parameters of the liquid film over a water-lubricated guide bearing and analyze the influence of the following liquid film geometric parameters on the dynamic and static performance of the water-lubricated guide bearing in reactor coolant pump under different working conditions using finite difference method, such as the eccentricity, radius gap and aspect ratio, etc. Results show that the bearing capacity and power loss increase with the rise of eccentricity and aspect ratio, and decrease with the rise of radius gap; the damping coefficient of the bearing increases with rising eccentricity and aspect ratio, and decreases with rising radius gap. To ensure the bearing capacity and liquid film stability and to minimize the power loss, the optimal geometric parameters are recommended as the eccentricity ranging from 0.5 to 0.7, the radius gap ranging from 0.2 mm to 0.3 mm, and the aspect ratio ranging from 0.8 to 1.0 for the water-lubricated guide bearing of a reactor coolant pump.