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    Power Equipment and System
  • Power Equipment and System
    Effect of Flue Gas Recirculation on Heat Transfer Performance of a Supercritical Carbon Dioxide Coal-fired Boiler
    YUAN Feng, CHEN Liang, WANG Chunbo, DAI Wenhao
    2022, 42(10): 889-896. https://doi.org/10.19805/j.cnkij.cspe.2022.10.001
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    For a 1 000 MW supercritical carbon dioxide (S-CO2) boiler, the cooling wall temperature was calculated and analyzed through the establishment of the boiler side combustion and heat transfer coupling model, and the flue gas recirculation was proposed to reduce the wall temperature. The effects of flue gas recirculation on cooling wall temperature, furnace exit flue gas temperature, exhaust gas temperature and working medium temperature at the outlet of the superheater and reheater were studied. The S-CO2 boiler was optimized and reformed for the flue gas temperature at the furnace outlet decreased and the exhaust gas temperature increased while only the flue gas recirculation scheme was adopted. Results show that when the flue gas recirculation rate is 20%, the maximum cooling wall temperature decreases from 690 ℃ to 640 ℃. When the 20% flue gas recirculation scheme is adopted, the flue gas temperature will be reduced from 143 ℃ to 123 ℃, and the boiler thermal efficiency will be increased from 92.8% to 94%. The H2S and CO mole fraction in the wall area decreases and the high-temperature corrosion rate decreases, showing that the flue gas recirculation scheme in the optimized boiler is feasible to reduce the wall temperature.
  • Power Equipment and System
    Microstructure Characteristics and Component Analysis of Packing Scaling in Wet Cooling Tower
    SONG Juanda, SUN Fengzhong, SUN Qinghang, LIU Tianwen, WANG Rui
    2022, 42(10): 897-903. https://doi.org/10.19805/j.cnkij.cspe.2022.10.002
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    In order to study the composition of limescale in cooling tower packing and explore the effective cleaning means, the limescale was extracted as the test sample and the components were analyzed by scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray fluorescence spectrometry (XRF) and infrared spectroscopy (FTIR). Results show that the main elements of packing scaling are O, Si, Ca, Al, etc, and the mass fraction of O element is higher,up to 50%, Si element and Al element account for about 20%. The main substances of packing scaling include SiO2, Al2O3, Fe2O3, Mg(OH)2, silicate, carbonate(mainly calcium carbonate), phosphate, sulfate, etc.
  • Power Equipment and System
    Study on Comprehensive Efficiency Improvement of Flow for a 330 MW Three-source Steam Heating Turbine Unit
    HUANG Silin, LIANG Zhanwei, QIAO Jiafei
    2022, 42(10): 904-911. https://doi.org/10.19805/j.cnkij.cspe.2022.10.003
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    To improve the overall operation efficiency and reduce the power supply coal consumption of thermal power unit, the optimization upgrade key technologies for three-source steam turbine flow passage with industrial heating were studied. The optimization schemes were proposed, and the feasibility and economy of different schemes were compared. The best optimization upgrade scheme of the three-source steam turbine flow passage was obtained. Results show that the original parameter flow efficiency improvement scheme is mature and reliable, which can improve the cylinder efficiency, reduce the heat consumption and have the reasonable cost and the shorter investment payback period. While the rising parameter flow efficiency improvement scheme has larger transformation range, higher investment and longer recovery life. Under original parameter flow efficiency improvement scheme, the heat consumption rate and standard power supply coal consumption are reduced by 222 kJ/(kW·h) and 8.79 g/(kW·h) respectively at heat consumption rate acceptance condition (THA condition),and 232 kJ/(kW·h) and 9.19 g/(kW·h) at rated heating condition. The investment recovery period of the scheme is 6.6 years, which has good economic benefits.
  • Power Equipment and System
    Combustion Performance Analysis and Engineering Practice of a F-class Gas Turbine with Hydrogen Addition
    LI Lixin, ZHANG Zhaozhao
    2022, 42(10): 912-918. https://doi.org/10.19805/j.cnkij.cspe.2022.10.004
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    To reduce the carbon emission and improve the operation flexibility of gas turbine power plants, a F-class heavy-duty gas turbine in the cogeneration unit of heat and power was retrofitted with hydrogen addition ratio of 15% to 30%. The key technical difficulties of its hybrid combustion with hydrogen were analyzed. The proposal for the retrofit of gas turbine and hydrogen unloading/loading was put forward. The performance of the retrofitted gas turbine and the adaptability of both heat recovery steam generator and steam turbine were analyzed. Results show that the combustion and output power of gas turbine are stable,and its NOx emissions qualifies. Stable hydrogen mixing process in the gas fuel system is achieved with high control accuracy. It is estimated that 15%~30% of hydrogen addition could reduce the annual CO2 emission by 11 000~28 400 tons. Expected performance of the retrofit is achieved.
  • Power Equipment and System
    Effect of Momentum Flux Ratio on Combustion Characteristics of Axial Staged Reburning Nozzle
    JIA Yuliang, LI Yuze, JIN Ming, ZHU Xutong, GE Bing, ZANG Shusheng
    2022, 42(10): 919-924. https://doi.org/10.19805/j.cnkij.cspe.2022.10.005
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    Aiming at the axial staged reburning nozzle,the experimental research methods such as particle image velocimetry (PIV) and flame CH photography were used to explore the variation laws of mixing of cross flow and jet, jet flame and pollutant emissions when the momentum flux ratio changed. Results show that changes of the momentum flux ratio have great influences on the mixing and flame position of cross flow and jet. The CO volume fraction decreased first and then increased with the increase of momentum flux ratio due to the combined action of mixing intensity and jet velocity. The increase of momentum flux ratio will lead to the change of recirculation intensity and the position of main reaction zone of jet flame, which will lead to the increase of NO volume fraction. For a specific reburning nozzle, there is an appropriate momentum flux ratio, so that the combustion chamber wall is not scoured by flame and the pollutant emissions remains at a low level.
    • New Energy Resources and Energy Storage
  • New Energy Resources and Energy Storage
    Zero Carbon Methanol Synthesis System Based on Green Hydrogen and Biomass Oxygen Enriched Combustion Technology
    XU Gang, ZHANG Zhong, WU Zhicong, XUE Xiaojun, CHEN Heng
    2022, 42(10): 925-932. https://doi.org/10.19805/j.cnkij.cspe.2022.10.006
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    In order to solve the problem of difficult storage and transportation of hydrogen energy, a zero carbon methanol synthesis system based on green hydrogen and biomass oxygen enriched combustion technology was proposed. The system used green power such as photovoltaic and wind power to produce hydrogen through alkaline electrolytic cell technology, and then used the tail gas rich in carbon dioxide produced by biomass oxygen enriched combustion power plant to synthesize methanol with hydrogen, realizing nearly zero carbon emission of the whole system. On this basis, the energy analysis and economic analysis of the proposed system were carried out. Results show that the comprehensive energy efficiency of zero carbon methanol synthesis system is 47.3%; When the electricity price is 0.2 ￥/(kW·h), the dynamic recovery period of the system is 4.24 years, and the net present value is 96.853 9 million yuan.
  • New Energy Resources and Energy Storage
    Dynamic Response Analysis of Floating Wind Turbine Platform in Local Mooring Creep Mode
    SUN Kang, JIN Jiangtao, LI Chun, LI Shujun, XU Zifei, XIAO Junqing
    2022, 42(10): 933-943. https://doi.org/10.19805/j.cnkij.cspe.2022.10.007
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    Aiming at the problem of mooring failure caused by creep and accelerated corrosion of floating wind turbine platform under the action of wind, wave and sea current for a long time, based on deep learning and chaos theory, the dynamic response of the wind turbine platform under local mooring failure was analyzed, focusing on the mooring creep occuring and the location of the creep mooring. Taking the 5 MW floating wind turbine developed by the National Renewable Energy Laboratory of the United States as the research object, the effectiveness of the proposed method was verified based on the Barge platform. Results show that the response in each degree of freedom increases sharply after mooring failure, but the changes of response is small during creep period. The bow roll response is more sensitive, and convolutional neural network and chaos can effectively identify the mooring state and creep mooring position, which is of great significance to prevent mooring failure and ensure the normal operation of the wind turbine.
  • New Energy Resources and Energy Storage
    Study on Start-up Performance of Small Variable-pitch Wind Turbine
    WU Shengsheng, BAO Daorina, WANG Tianbo, LIU Zhifeng, LIU Hengxin, LIU Dong
    2022, 42(10): 944-950. https://doi.org/10.19805/j.cnkij.cspe.2022.10.008
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    In order to study the start-up performance of a small horizontal-axis variable-pitch wind turbine, a wind tunnel test platform was built to analyze the influence of different pitch angles on the static torque, rotational speed and starting wind speed of the wind turbine. The relative aerodynamic characteristics of the wind turbine during the change of pitch angle were studied by numerical simulation and theoretical analysis. Results show that when the wind speed is kept constant at 3~6 m/s ,the static torque value of the wind rotor first increases and then decreases with the increase of the pitch angle, and the static torque at 50° pitch angle is about 2.2 times of that at 10° pitch angle. When the rotor is stationary, the aerodynamic performance is completely opposite to that in the high-speed rotation state, and the blade root area is the main power generation area for the starting torque. The smaller the pitch angle becomes, the more obvious the flow separation phenomenon in the blade root area is, the closer the separation point is to the leading edge, and the worse the aerodynamic performance is.At the pitch angle of 40°, the minimum starting wind speed and the larger rotation speed can be achieved, and the minimum starting wind speed is 3.7 m/s.
    • Digitalization and Intelligentization
  • Digitalization and Intelligentization
    Fault Identification of Rolling Bearings Based on Optimized Variational Mode Decomposition and Chaotic Fractal
    SUN Kang, JIN Jiangtao, LI Chun, XU Zifei
    2022, 42(10): 951-959. https://doi.org/10.19805/j.cnkij.cspe.2022.10.009
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    In order to accurately identify the fault types of rolling bearings, the chaos characteristics of strong nonlinear and non-stationary signals were analyzed. Combined with Lyapunov index, an optimized variational mode decomposition (OLVMD) method was proposed to realize noise reduction and select sensitive components to reconstruct fault signals. The fractal theory was introduced to improve the traditional method to calculate correlation dimension by using the square sum of fitting deviation. Then the chaotic correlation dimensions of bearings in different states were calculated by this improved method, and the experimental data of damaged bearings were analyzed. Results show that OLVMD method can effectively eliminate the irrelevant components and the redundant effects. The correlation dimensions of bearings in different states are significantly different, which can be used as the basis for monitoring and diagnosis of bearing working conditions, and the method has good robustness and generalization.
  • Digitalization and Intelligentization
    Research of On-line Measurement of Temperature Field in Furnaces Based on Deep Learning Coupled Thermal Radiative Imaging
    TANG Guangtong, XU Yefeng, YAN Huibo, WANG Chaoyang, LIU Zhiqiang, LOU Chun
    2022, 42(10): 960-966. https://doi.org/10.19805/j.cnkij.cspe.2022.10.010
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    Thermal radiative imaging model was used to calculate the training data, and the temperature field in furnace was reconstructed based on multi-layer perceptron (MLP) neural network. Taking a 300 MW boiler as an example, the online measurement experiment was carried out and the influence of fuel and air volume on temperature was analyzed by boiler load adjustment. Results show that the maximum relative error of the reconstruction results of the MLP neural network for different temperature fields is less than 2%, and the maximum relative error after adding noise is also less than 4%, which has good generalization, prediction, and anti-noise ability. The increase trend of furnace temperature is significantly faster than that of load, and the influence of air volume on unit load is greater. The proposed online measurement system of furnace temperature field coupled with deep learning and thermal radiative imaging has good application potential in improving the flexible peak regulation ability of coal-fired power units.
    • Green Energy and Low-carbon Technology
  • Green Energy and Low-carbon Technology
    Techno-economic Analysis of Ceramic Membrane-based Flue Gas Water and Heat Recovery System in a Power Plant
    DU Ziwei, CHEN Haiping, HUANG Jiguang, ZHAO Chunhao, ZHANG Heng
    2022, 42(10): 967-976. https://doi.org/10.19805/j.cnkij.cspe.2022.10.011
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    Porous ceramic membrane was used to recover water and waste heat from the flue gas, and the recovered heat was incorporated into the thermal system of the power plant. The water saving and energy saving potential of the membrane-based flue gas water and heat recovery system was evaluated from the perspective of thermal economy of the whole plant. Taking a 330 MW coal-fired generator set as an example, the ceramic membrane module with 1 300 m2 membrane area was installed in the flue gas duct at the tail end of the desulfurization tower. Combined with the heat pump technology, the recovered flue gas waste heat was used to heat the return water of the heating network, and the recovered water was poured into the cooling tower for water supplement in the power plant. The mathematical model of the whole thermal system of the coupled membrane flue gas water and heat recovery system was established, and the techno-economic analysis of the system was carried out.Results show that the increase of cooling water flow and the decrease of inlet temperature will increase the water and heat recovery of the system, but can not improve the coal saving rate. The system can achieve water recovery of up to 35.74 kg/(m2·h), coal saving rate of 1.37 g/(kW·h), annual coal saving of 677.84 t, and water saving of 233 254.04 t. The investment recovery period of the system is 5.2 years.
  • Green Energy and Low-carbon Technology
    Thermodynamic Analysis of Condensation Water and Waste Heat Recovery of Coal-fired Flue Gas
    BAI Tao, JIN Zhiping
    2022, 42(10): 977-985. https://doi.org/10.19805/j.cnkij.cspe.2022.10.012
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    In view of the problem that wet plume was generated if saturated wet flue gas was directly discharged into the environment after wet flue gas desulfurization was adopted in coal-fired power plant boilers, a mathematical model of wet plume was established. Results show that by using low temperature economizer, when the flue gas temperature is reduced from 130 ℃ to 90 ℃, 21.477 MW of heat can be recovered. By using water plume elimination technology, when the ambient relative humidity is 10% and the ambient temperature is -20 ℃, the condensate water is 144.215 t/h, and 109.603 MW energy recovered. With the increase of ambient temperature, the recovered condensate water quantity and flue gas waste heat gradually decrease. And different coal quality has different effects on flue gas condensation water saving and waste heat recovery.
  • Green Energy and Low-carbon Technology
    Effect of NO on SO3 Formation in the Oxygen-enriched Combustion
    GUI Ben, GUO Junzhe, HU Yuqing, CHEN Mu, LIU Yu, ZHOU Zijian, LIU Xiaowei
    2022, 42(10): 986-992. https://doi.org/10.19805/j.cnkij.cspe.2022.10.013
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    Homogeneous/heterogeneous experiments were carried out to investigate the effect of NO on the formation of SO3 in the oxy-fuel combustion. Sensitivity analysis was performed by Chemkin-PRO software. Results show that NO can promote SO3 formation in both homogeneous and heterogeneous experiments. In the homogeneous experiments, SO3 volume fraction rises monotonously with the increase of NO volume fraction, and its growth rate gradually slows down. The sensitivity analysis shows that NO promote the formation of SO3 by increasing O radicals and consuming of HO2 and H radicals. In the heterogeneous reactions, the SO3 volume fraction increases firstly and then decreases. Excessive NO volume fraction will inhibit the formation of SO3, which may be caused by the competition of O radicals between NO oxidation and SO2 oxidation. It may also be caused by the decrease of burnout rate and incomplete release of S element in pulverized coal under high NO volume fraction.