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  • 2020 Volume 40 Issue 1
    Published: 15 January 2020
      
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  • Quantitative Evaluation of the Slagging in a 1 000 MW Tower Boiler Formed During Combustion Process
    ZHANG Li, NIU Hao, GE Shuai
    2020, 40(1): 1-7. https://doi.org/10.19805/j.cnki.jcspe.2020.01.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the 1 000 MW tower boiler as an object of study, the process of pulverized coal combustion in the furnace was simulated, during which, the distribution of velocity field and temperature field in the boiler was obtained, and subsequently, evaluation models were summarized for the slagging status in the furnace, including the mass concentration of fired particles colliding the wall, the probability and growth rate of wall slagging, etc., and finally the distribution of above parameters in the furnace was acquired based on numerical simulation, so as to evaluate the slagging condition in the tower boiler in detail. Results show that slagging tends to appear in the burner zone and in the downstream of burners and SOFA nozzles. The growth rate of slagging lies in the order of magnitude of 10-12 m/s. Compared with the rated condition, the area and growth rate of slagging in the furnace reduce under 70% load condition.
  • Experimental Study on the Reduction of Gas Temperature Deviation in a 660 MW Tangentially Fired Boiler
    LONG Dunwu, LI Pei, SHI Zifu, ZHOU Yonggang, ZHAO Hong
    2020, 40(1): 8-13. https://doi.org/10.19805/j.cnki.jcspe.2020.01.002
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    To solve the problem of high deviation of heat absorption on left and right side in the superheater area of a 660 MW tangentially-fired pulverized coal boiler caused by gas temperature deviation on the both sides, field tests were carried out in the furnace to study how the deviation of the opening of the angle damper in the single-layer and multi-layer SOFA zone effects the heat absorption deviation on both sides of the superheater area, as well as the gas temperature deviation at furnace outlet. Results show that when the opening offset of SOFA angle damper is adjusted separately for the E, D and C layer, the heat absorption deviation on both sides of the superheater area is small, and the gas temperature deviation changes in different laws on the both sides of furnace outlet. At the same time, when the opening offset is adjusted simultaneously for the SOFA angle dampers in upper three layers, the heat absorption in the superheater area increases on side A, and decreases on side B. The deviation of outlet gas temperature increases on both sides of the furnace as the opening offset of the angle damper increases.
  • Influence Mechanism of Real Gas Parameters on Static and Dynamic Characteristics of Labyrinth Seals
    SUN Dan, ZOU Jinglan, ZHAO Huan, XIAO Zhonghui, MENG Jigang, YU Xiaodan
    2020, 40(1): 14-22. https://doi.org/10.19805/j.cnki.jcspe.2020.01.003
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    A theoretical analysis was conducted on the formula to calculate the leakage rate of labyrinth seals considering actual gas parameters and on the equation for the flow control. Based on the rotor multi-frequency elliptic vortex method, the effects of medium category and real gas parameters on the static and dynamic characteristics of labyrinth seals were studied. Results show that the molar mass of gas is positively correlated with the leakage rate of labyrinth seals. At the same frequency of rotor vortex oscillation, the absolute values of direct stiffness coefficient and of main and cross damping coefficient increase with the rise of the molar mass of gas. The flow force increases as the molar mass of gas rises, and the flow force of medium CO2 is 1.63 times as much as CH4. As the frequency of vortex oscillation increases, the influence of molar mass on the damping coefficient gradually transfers from the inertial effect to the frictional effect, therefore, as the molar mass of gas increases, the effective damping coefficient increases at low frequency and decreases at high frequency.
  • Stall Mechanism Study and Stall Process Modal Analysis for a Transonic Axial Compressor
    LIU Zhenxiong
    2020, 40(1): 23-30. https://doi.org/10.19805/j.cnki.jcspe.2020.01.004
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    To study the stall mechanism of a transonic axial compressor, numerical simulations were conducted on the NASA Rotor 35 combined with throttle valve model. To further research the variation behavior of the flow field during stall process, an analysis was carried out on the flow field in the tip region using the method of proper orthogonal decomposition (POD). Results show that the stall originates in the tip region of blade and develops into a stall cell rotating coaxially with the rotor in the same direction but with lower speed. By comparing the flow field characteristics at different time, the leakage flow is found to exist throughout the process of stall development, which could be taken as a basis for judgment of flow field worsening. Meanwhile, the structure of large-scale unsteady flow could be identified in the flow field during stall process.
  • Conjugate Heat Transfer Simulation of Film Cooling on Trailing Edge Cutback of Gas Turbine Blades
    ZHANG Ling, SHI Mengying, GUO Qing, HONG Wenpeng
    2020, 40(1): 31-38. https://doi.org/10.19805/j.cnki.jcspe.2020.01.005
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    A conjugate heat transfer simulation was conducted on the film cooling flow field at the trailing edge of gas turbine blades, and the simulation results were compared with that of adiabatic method, thus finding the film cooling behavior at different blow ratios and suction surface thickness. Results show that compared with the adiabatic method, the curve of film cooling efficiency obtained by conjugate method is more gentle, with more uniform temperature distribution on the suction surface but a higher temperature gradient above the pressure surface. Increasing the blow ratio could reduce the effect of heat conduction on film cooling and inhibit the separation of the fluid from wall surface effectively. As the thickness of the suction surface increases, the fluid temperature in the area from 0.6 to 0.76 isotherm changes, the temperature rises in the downstream of cutback outlet and decreases in the place far from the cutback.
  • Study on Gas-Liquid Two-phase Flow in a Vertical Rectangular Narrow Channel
    LI Kun, YAN Tianyu, SUI Zhiqiang, BI Qincheng
    2020, 40(1): 39-43. https://doi.org/10.19805/j.cnki.jcspe.2020.01.006
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    An experimental system was set up to study the gas-liquid two-phase flow in a vertical rectangular narrow channel, based on which, the gas-liquid two-phase flow was visualized by a high-speed camera, and subsequently the automatic images were recognized, while close bubbles were discriminated using Matlab software. Results show that the relationship between average void fraction α and volume void fraction β is found to be α=0.88β. The calculated results have a high matching degree with the experimental measurements after the coefficient C of Chen model is revised.
  • Design of a Wet Flue Gas Desulfurization Control System Based on Dynamic Matrix Algorithm
    SHU Jian, ZHENG Chenghang, GUO Yishan, LIU Bowen, LI Qinwu, WENG Weiguo, YU Baoyun, GAO Xiang
    2020, 40(1): 44-50. https://doi.org/10.19805/j.cnki.jcspe.2020.01.007
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    To solve the problem that the desulfurization system is difficult to run stably, economically and efficiently when the fuel and load change suddenly, an optimized control strategy was proposed for the desulfurization system based on dynamic matrix control (DMC). A variable-speed pump was introduced to realize the locally continuous adjustment of slurry spray, and the parameters of the transfer function were optimized by combining the particle swarm optimization algorithm with the mechanism model, following which, a control strategy based on DMC was established to achieve energy-saving control under the condition ensuring the quality of control. The optimized DMC and PID control strategies were then applied to the desulfurization control system of a 220 t/h boiler. Results show that compared with PID control, the outlet SO2 concentration of the desulfurization system under DMC control varies in a relatively narraw range, with a more concentrated distribution of outlet SO2 concentration, and better control quality. The total current under variable-frequency control is 50-110 A lower than that under manual control, indicating good energy saving effectiveness.
  • Experimental Study on the Concentration of FGD Wastewater Using Low-temperature Flue Gas
    MA Shuangchen, CHEN Jianing, LIU Ning, WAN Zhongcheng, CHAI Jin, YUE Peiheng, ZHANG Jingrui, LIANG Weiqing
    2020, 40(1): 51-57. https://doi.org/10.19805/j.cnki.jcspe.2020.01.008
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    A flue gas concentration test bench was built to conduct the experiments on saline solution and desulfurization wastewater from an actual power plant in the new method of "water curtain" spray by combining the orthogonal experiment with single factor experiment, during which, the effects of following factors on the water evaporation by flue gas were explored, such as the gas flow rate, inlet gas temperature, inlet water flow rate and conductivity of brine on flue gas, etc. Results show that under optimal experimental conditions, the maximum evaporating capacity per unit volume of flue gas is 15.33 mL/m3. The gas flow rate has the most significant influence on the evaporation capacity, followed by the inlet gas temperature and inlet water flow rate. What's more, there is a low risk of nozzle blockage using the "water curtain" spray method. The main content of evaporation product is found to be NaCl.
  • Comparison of Dynamic Response Among Three Offshore Wind Turbine Semi-submersible Platforms Under Extreme Sea Conditions
    WANG Bo, XU Zifei, LI Chun, DENG Yunhe, LIU Qingsong
    2020, 40(1): 58-64. https://doi.org/10.19805/j.cnki.jcspe.2020.01.009
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    Numerical simulations were conducted on motion responses of the three-floating three-column, four-floating four-column and five-floating five-column semi-submersible platform in complicated marine environments using hydrodynamic software AQWA combined with finite element analysis, while their frequency-domain response and time-domain response were analyzed. Results show that in the frequency-domain analysis, the added mass of the three-floating three-column, four-floating four-column and five-floating five-column semi-submersible platform increase sequentially in the sway, heave and roll direction, and their motion response decreases in turn; in the time-domain analysis, the sway, heave and roll motion response of all the three floating platforms reduce. With the increase of structure complexity, the stability of above platforms improves. Compared with the four-floating four-column platform, the increase in stability of the five-floating five-column platform is not obvious.
  • Experimental Study on the Noise Reduction of a Tilted Sawtooth Trailing Edge Blade
    MA Yang, YANG Ailing, CHEN Eryun
    2020, 40(1): 65-69. https://doi.org/10.19805/j.cnki.jcspe.2020.01.010
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    To suppress the narrow band pure tone noise generated by a non-flat serrated trailing edge, taking the NACA65019 blade as an object of study, a tilted sawtooth trailing edge was newly designed and tested in a fully anechoic wind tunnel. Results show that the tilted sawtooth trailing edge can weaken the narrow band peaks caused by traditional blunt trailing edge and ensure the noise reduction effect in the high frequency range at a small inflow angle of attack. Whereas, at a large angle of attack, the blunt trailing edge does not produce narrow bank peaks and has a certain effect in noise reduction, but the tilted sawtooth trailing edge has more obvious effect in noise reduction.
  • Design and Off-design Performance Analysis of a Radial-inflow Turbine with Organic Working Fluid
    HAN Zhonghe, JIA Xiaoqiang, LI Peng
    2020, 40(1): 70-75. https://doi.org/10.19805/j.cnki.jcspe.2020.01.011
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    Thermodynamic design and aerodynamic design were conducted on a radial-inflow turbine using iteration method and screening method, respectively, while an analysis was carried out on off-design performance of the turbine using three-dimensional numerical simulation. Results show that under different inlet mass flow rates, the total to total efficiency varies in different laws with the relative rotational speed. At larger inlet mass flow rates, the maximum efficiency corresponds to the lowest relative rotational speed. At the design inlet flow rate, the radial-inflow turbine could work stably at higher efficiency in a certain range of relative rotational speed. When the inlet flow rate is constant, the power output rises first and then drops with the increase of relative rotational speed; whereas, when the rotational speed is constant, the power output increases with the enhancement of inlet mass flow rate; the variance amplitude of power output reduces with rising relative rotational speed.
  • Experimental Study and Application Analysis of a Device for Synergetic Recovery of Flue Gas Waste Heat and Condensation Water
    WANG Xia, WU Kai, ZHU Xiaolei, MENG Ji'an
    2020, 40(1): 76-81. https://doi.org/10.19805/j.cnki.jcspe.2020.01.012
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    To achieve simultaneous recovery of flue gas waste heat and condensation water after the desulfurization tower during white smoke elimination process, hot-state experiments were conducted in a certain heating boiler using the spray packed heat exchanger and heat pump technology, following which, the heat and mass transfer characteristics in the tower were investigated. The system proposed was then applied to large coal-fired heating (cooling) units. Results show that compared with the direct contact heat exchanger of empty-tower spray type, the pressure drop between inlet and outlet of the spray packed heat exchanger could be reduced by 55%, with a reduction in power consumption of fan by 50%, a reduction in power consumption of pump by 57%, an improvement on the ability of flue gas waste heat recovery by 30% and an improvement on the effect of white-smoke elimination by 20%, showing good effectiveness in the recovery of flue gas waste heat and condensation water.
  • Cavitation Erosion Behavior of 17-4PH Steam Turbine Blades Treated by Laser Solid Solution
    XUE Chenggan, PAN Huibin, DING Yinping, WANG Liang, LIU Rong, SHENG Jiajin, YAO Jianhua
    2020, 40(1): 82-88. https://doi.org/10.19805/j.cnki.jcspe.2020.01.013
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    To improve the cavitation resistance of steam turbine blades, the surface of 17-4PH stainless steel was treated by laser solid solution and aging treatment. Ultrasonic cavitation tests were carried out in a 3.5% sodium chloride (NaCl) aqueous solution to evaluate the cavitation resistance of the material and reveal the mechanism of cavitation failure. The surface morphology and microstructure evolution after cavitation test were analyzed by means of metallographic microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and 3D ultra-depth-field microscopy, while the hardness of the material was measured by microhardness tester. Results show that a 2 mm thick hardened layer could be obtained by laser solid solution and aging treatment. The surface hardness of 17-4PH after laser surface strengthening is significantly improved. The maximum hardness of the strengthened layer is 491 HV0.2, which is 116 HV0.2 higher than the matrix. Due to the precipitation of dispersive strengthening phase ε-Cu, the cumulative weight loss and surface roughness of the laser-surface-strengthened 17-4PH after 40 hours of cavitation test is 60% and 47% of the matrix, respectively.