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    Boiler Technology
  • Boiler Technology
    Real Time Optimization Strategy for Air Cooling Island Operation of Coal Fired Power Station Based on Big Data
    NIE Chunming, AN Liuming, XU Gang, CHEN Heng, LI Ji
    2021, 41(9): 713-720. https://doi.org/10.19805/j.cnki.jcspe.2021.09.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to improve the energy saving effect of 2×600 MW supercritical direct air-cooled coal-fired unit, the big data analysis method was adopted, and the best database was obtained by selecting the historical operation data of the unit. The BP neural network prediction model was established to predict the real-time net generating power of the unit. Finally, the optimal back pressure of real-time unit operation data corresponding to load and corresponding boundary conditions was found out from the back pressure bias range of real-time unit operation, so as to guide its operation optimization level and calculate its power saving. Results show that the optimization effect is more stable by using the optimal back pressure method, and the energy saving effect is more obvious when the ambient temperature is lower or the unit is in the middle load operation.
  • Boiler Technology
    Study on Combustion Characteristics of Guizhou Anthracite Coal Char Based on Thermogravimetric Analysis of a Micro Fluidized Bed
    MENG Qingsong, LI Zhenshan, WANG Shihui, LI Weicheng, LI Guo
    2021, 41(9): 721-728. https://doi.org/10.19805/j.cnki.jcspe.2021.09.002
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    The combustion characteristics of Guizhou Weihe anthracite char were studied in a micro fluidized bed thermogravimetric analysis system. The curves of char conversion ratio vs. time under different temperatures, particle sizes and O2 volume fractions were obtained. The competitive relationship between reaction and diffusion rate of coal char was obtained by data analysis. Results show that the combustion rate of coal char first increases linearly with the decrease of particle size, and there is a turning point at the particle size of 0.4-0.6 mm, then the combustion rate increases slowly with the decrease of particle size. This finding exists in the combustion of different O2 volume fractions. Increasing the temperature can't fundamentally improve the burnout of Weihe coal with large particle size. Increasing the bed temperature can increase the combustion and burnout rate of coal char with particle size less than 0.6 mm and reduce the unburnt carbon content of fly ash. For coal char with particle size larger than 3 mm, increasing bed temperature can't increase the combustion rate, but increasing the oxygen content in dense phase zone can increase the combustion rate and decrease the unburnt carbon content in bottom slag.
  • Boiler Technology
    Influence of Separated Over Fire Air on CO and H2S Formation Characteristic of a Lean Coal-fired Boiler
    XIE Zhaoxiang, LING Peng, ZHAN Fang, ZHANG Wenpeng, LI Shiqiang, XU Kai, SU Sheng, XIANG Jun
    2021, 41(9): 729-735. https://doi.org/10.19805/j.cnki.jcspe.2021.09.003
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    Numerical simulation was carried out on a 330 MW tangential lean coal-fired boiler after its low-nitrogen combustion retrofit. The influence of separated over fire air (SOFA) rate on the velocity field, temperature field, CO concentration field, O2 concentration field, H2S concentration field and outlet flue gas parameters was studied under 300 MW load, and the results were compared with the field test values. Results show that SOFA rate has an important influence on the combustion and CO/H2S formation characteristics. With the increase of SOFA rate, CO concentration at the furnace outlet gradually increases, and NOx concentration at the furnace outlet decreases. Reducing SOFA rate is beneficial to inhibit the occurrence of high temperature corrosion and slagging in the furnace. Comprehensively considering the boiler operation safety, economy and NOx formation characteristics, 25% is a more appropriate value to set SOFA rate.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Optimization of Fan-shaped Film Hole Based on Surrogate Model and Parameter Sensitivity Analysis
    GUAN Junjun, ZHANG Yi, ZHANG Yeping, BAO Amei, DAI Ren
    2021, 41(9): 736-742. https://doi.org/10.19805/j.cnki.jcspe.2021.09.004
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    In order to obtain higher cooling efficiency, the two-step method was used to optimize the geometry of fan-shaped film holes. In the first step, taking the leading edge length L1, trailing edge length L2, exit width H and cylinder segment length Lm as optimization variables, the first round Latin hypercube sample space was constructed, and the sensitivity of the objective function to each optimization variable was obtained based on parameter sensitivity analysis. In the second step, high sensitive parameters were selected to generate the second round of parameter sample space, and the Kriging surrogate model was constructed. Finally, multi-island genetic algorithm was used for optimization. Results show that L1, L2 and Lm would significantly affect surface average cooling efficiency with high sensitivity, while the sensitivity of H is the least. After reducing dimension of parameters by sensitivity analysis, the prediction accuracy of the surrogate model can be improved. Surface average cooling efficiency of the optimized hole obtained by two-step method is higher than that of one-step optimization, and the convergence of the optimization results can be improved.
    • Automatic Control
  • Automatic Control
    Optimal Control of SCR Denitrification System Based on Improved Fuzzy Linear Active Disturbance Rejection Controller
    DU Ming, NIU Yuguang, PAN Xiangfeng, CAO Guoqing, MA Qiang, ZHUANG Zhibao
    2021, 41(9): 743-748. https://doi.org/10.19805/j.cnki.jcspe.2021.09.005
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    An improved fuzzy linear active disturbance rejection controller (Fuzzy-MLADRC) was proposed. High-order inertial element was employed to compensate the large delay characteristics of the system in the controller, and fuzzy rules were also used to adjust parameters of the controller appropriately. The controller was then simulated in SCR denitration system and the results were compared with that of other controllers. Results show that the proposed controller can achieve more satisfactory set point tracking ability on a large delay and large inertial system, which has stronger robustness than other controllers in the case of model mismatch.
  • Automatic Control
    Risk Assessment of Control System Actuator Based on IFAHP-TOPSIS Method
    ZHANG Wenguang, SHEN Yangzhi, LI Haohan, YUAN Guili
    2021, 41(9): 749-757. https://doi.org/10.19805/j.cnki.jcspe.2021.09.006
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    Aiming at different kinds of actuator faults in control system, a method of combining improved fuzzy analytic hierarchy process with technique for order preference by similarity to an ideal solution (IFAHP-TOPSIS) was proposed. Analytic hierarchy process (AHP) was used to establish the risk assessment index system, and IFAHP was used to calculate complex weight of risk assessment index by subjective and objective dynamic combination weighting method. Then, the final sequence of each failure mode was obtained using improved fuzzy technique for order preference by similarity to an ideal solution (IFTOPSIS). Finally, numerical analysis was carried out by taking the pneumatic actuator in a gas turbine power plant as an example. Results show that evaluation results of the proposed IFAHP-TOPSIS method are basically consistent with actual situation. Compared with the traditional AHP-TOPSIS method, it can deal with uncertain factors in the risk assessment process, reduce subjective sensitivity, solve the reverse order problem of the traditional TOPSIS method, and improve the accuracy of the risk assessment method.
    • Auxiliary Equipment Technology
  • Auxiliary Equipment Technology
    A Method for Modal Analysis of Rotor System of Four-stage Centrifugal Pump
    GAO Hongbin, GONG Yichao, HUO Xiaohua
    2021, 41(9): 758-765. https://doi.org/10.19805/j.cnki.jcspe.2021.09.007
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    To improve the analytical method for solving the modal accuracy of the four-stage centrifugal pump rotor system under the condition of impeller with mass balance and mass eccentricity,a simplified lumped mass mathematical model and ANSYS were used respectively to solve the natural frequency of the rotor system of impeller with mass balance. By analyzing the differences between the two results,an optimized mathematical model combining the shafting mass and the correction coefficient of modal stiffness was presented.The new model was used to solve the natural frequencies of the rotor system under normal and eccentric conditions, and the calculation results under eccentricity were compared with the ANSYS simulation results. Results show that the natural frequency obtained by the analytical method is slightly smaller; the error of the first four-order natural frequency is reduced respectively from 1.28%, 2.03%, 8.64%, 11.82% before optimization to 0.77%, 1.02%, 3.41%, 4.52% after optimization,and the simplification of stiffness is the main factor that causes the error to be large; the natural frequencies of each order increase slightly when the mass is eccentric,and the closer the impeller of mass eccentricity to the suction chamber side, the greater the influence on the natural frequency; the error of solving the natural frequency of the impeller with mass eccentricity is greater than that of mass balance eccentricity in the optimized model.
    • Environmental Protection Technology and Equipment
  • Environmental Protection Technology and Equipment
    Numerical Simulation Optimization and Application of Wet Desulfurization Tower with Inner Guide Plate
    TIAN Senhao, XIANG Yonglin, CHEN Donglin, ZHENG Bingwen, SONG Cheng, LIU Bin, LIU Lianghua
    2021, 41(9): 766-772. https://doi.org/10.19805/j.cnki.jcspe.2021.09.008
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    According to the problem of ubiquitous low desulfurization efficiency and excessive resistance loss in traditional wet desulfurization system, a retrofit scheme of flow field optimization, efficiency enhancement and resistance reduction was proposed based on guide-plate. Numerical simulation method was used to study the effects of guide plate schemes on flow field distribution and flow resistance characteristics in desulfurization tower. The optimal arrangement was determined and then applied in the retrofit of desulfurization tower in a 600 MW boiler of power plant. Results show that the uniformity of flue gas in tower can be improved obviously after retrofit. The relative standard deviation of flow velocity above 1.5 m of tray can be decreased from 52.5% to 18.7%. At the main operation load range (300-480 MW), the SO2 concentration of flue gas at outlet can be reduced by about 10 mg/m3. The critical operation load can be improved from 390-410 MW to 430-450 MW in the condition of three slurry circulation pumps running. The flow resistance can be reduced by about 100 Pa than before in the same circulation pump operation parameters within a certain load range.
  • Environmental Protection Technology and Equipment
    Experimental Study on Removal of SO3 Acid Mist Aerosol Under Low Temperature
    MI Chenfeng, MA Suxia
    2021, 41(9): 773-777. https://doi.org/10.19805/j.cnki.jcspe.2021.09.009
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    In order to analyze the removal characteristics of SO3 acid mist aerosol, a set of device for the formation and removal of the aerosol was developed, and the effects of temperature, molar ratio, types of alkaline sorbents, incident angle and volume flow rate of atomized gas on the removal efficiency were studied. Results show that when the temperature is lower than 52℃, chemical reaction rate acts as the main controlling factor of the reaction, it can increase with the increase of the temperature, and the removal efficiency can increase by 21% when the temperature is raised from 40℃ to 52℃ and the molar ratio is 2; when the molar ratio is less than 3, the removal efficiency can be improved via increasing the molar ratio; types of alkaline sorbents have no obvious effects on the removal efficiency; the surface area of alkaline sorbent spray droplets increases with the increase of the volume flow rate of atomized gas; the removal efficiency for the volume flow rate of atomized gas of 12.5 L/min is 10% higher than that of 7.5 L/min; compared with 90° incident angle, the removal efficiency is 13% higher at 135° incident angle.
  • Environmental Protection Technology and Equipment
    Adsorption Performance Study of Elemental Mercury on Iron-based Biochar Modified by Mn-Ce
    ZHANG Yongqiang, JIA Li, QIAO Xiaolei, GUO Jinrong, LI Zepeng, FAN Baoguo
    2021, 41(9): 778-785. https://doi.org/10.19805/j.cnki.jcspe.2021.09.010
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    The iron-based biochar was modified by bimetals Mn and Ce using the combined sol-gel and co-precipitation methods. And its mercury adsorption performance was examined. The pore structure, element valence and surface functional groups of the biochar were characterized to explore its adsorption mechanism after modification. The apparent activation energy of modified biochar was obtained by Arrhenius equation. Results show that 5%Ce1%Mn-FeBC sample has the best mercury adsorption performance, and its cumulative mercury adsorption capacity in 3 hours is achieved at 11 926 ng/g. Metal Ce not only participates in the mercury adsorption reaction directly, but also synergizes with other metals to adsorb elemental mercury by providing lattice oxygen. After modification, the biochar is abundant in oxygen functional groups, which improves the mercury adsorption performance significantly. Chemical adsorption is the rate controlling step of mercury adsorption on the biochar surface.
    • New Energy
  • New Energy
    DBSCAN and SDAE-based Abnormal Condition Early Warning for a Wind Turbine Unit
    MA Liangyu, SUN Jiaming, YU Shilei, ZHAO Shangyu
    2021, 41(9): 786-793. https://doi.org/10.19805/j.cnki.jcspe.2021.09.011
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    A combination of density-based spatial clustering of applications with noise (DBSCAN) method and stacked denoising auto-encoder (SDAE) was proposed for wind turbine normal operating performance prediction and abnormal condition early warning. Firstly,the DBSCAN algorithm was used to clean the historical operation data of the wind unit SCADA system,then the normal operating performance prediction model was established with SDAE. Based on this model,the time shift sliding window method was adopted to construct the identification index,which can accurately reflect the abnormal state of the wind turbine, and the index threshold was determined according to the statistical interval estimation theory. The fault replay test was performed by using the real historical operation data of a wind turbine. Results show that this method can timely warn the abnormal operation conditions of wind turbines before the fault occurs, which verifies the effectiveness of this method.
  • New Energy
    Analysis on the Mechanical Response to Wind Vibration and Buckling of Offshore Super Large Wind Turbines by Multi-layer Soil-structure Interaction
    LI Zhihao, YAN Yangtian, YUE Minnan, LI Chun, YANG Yang, XUE Shicheng
    2021, 41(9): 794-801. https://doi.org/10.19805/j.cnki.jcspe.2021.09.012
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    Taking the offshore DTU 10 MW super large wind turbine as the research object, the measured seabed soil parameters in the East China Sea were selected to construct the horizontal resistance-pile deformation (p-y) curve of pile foundation. Based on the nonlinear spring element, the pile-soil coupling effect models of pure sand, pure clay and multiple soil layers were established. The measured seismic displacement data were selected as the seismic load. The mechanical responses of wind turbine under three pile-soil coupling effects were studied by using finite element method. Results show that the peak values of tower top displacement, forward and backward displacement, lateral displacement and their fluctuations under the soil-structure coupling effect of the multiple soil layers are less severe than those of pure sand soil, but greater than those of pure clay soil. Using pure sand soil or pure clay soil to construct the pile-soil coupling effect model will lead to inaccurate response results. Under different soil-structure coupling effects, the first mode of the tower is induced by seismic loads. The buckling factor of the tower under the soil-structure coupling effect of the pure sand soil is the smallest, followed by the multiple soil layer and that of the pure clay soil is the biggest. The peak value of the maximum shear stress of the tower is located at the support structure of the tower. Local buckling is easy to occur at the lower end of the tower under the action of earthquake, which should be paid attention to in the structural design.
    • System Engineering
  • System Engineering
    Simulation and Efficiency Analysis of Advanced Compressed Air Energy Storage System
    WEN Xiankui, LIU Shi, LI Xiang, DENG Tongtian, ZHONG Jingliang, WANG Suobin, HE Xinbing
    2021, 41(9): 802-808. https://doi.org/10.19805/j.cnki.jcspe.2021.09.013
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    To solve the effect of temperature changes on equipment materials of the compressed air energy storage system and system efficiency, a method of controlling temperature changes was proposed, which was realized by adjusting air mass flow. In addition, the system model was established by using Aspen Plus Dynamics software, so as to study the influence of inlet air temperature and flow ratio on system efficiency. Results show that system efficiency under the variable compression ratio is higher than that of the constant compression ratio. The influence of inlet air temperature on system efficiency is not obvious. When the flow ratio is the same, the variation range of system efficiency is small. System efficiency can be improved by keeping the mass flow of working fluid constant and reducing the mass flow of inlet air.