Power Equipment

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  • 2019 Volume 33 Issue 5
    Published: 15 September 2019
      
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  • Application of Data Rectification in Calculation of Steam Turbine Exhaust Enthalpy in a Gas-Steam Combined Cycle Unit
    Zhang Haofeng, Xu Jianqun, Huang Xijun, Chen Xiaoxin, Huangfu Zeyu
    2019, 33(5): 297-303.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the steam turbine in a combined cycle unit as an object of study, the power method and the circulating cooling water mass flow method were proposed for the calculation of exhaust enthalpy by processing the measured data through data rectification based on the precision of different measuring instruments. Results show that data rectification can effectively improve the measurement accuracy, which helps to reduce the standard deviation of condensate mass flow from 2.460 t/h to 0.775 t/h. The calculation precision of exhaust enthalpy is related to the measurement precision of relative instruments, and the exhaust enthalpy calculated by the power method is more accurate and stable than that by the circulating cooling water mass flow method.
  • Simulation Prediction of Wear Sites Distributions on Inlet Impingement Plate and Shell Wall of a Feedwater Heater
    Chen Xiaoxin, Xu Jianqun, Jiang Weili
    2019, 33(5): 304-308.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the simplified model of high pressure heater, a three-dimensional modeling method was developed and a steam-water two-phase flow erosion model was established to predict the possible wear sites on the shell wall and impingement plate of the heater, and subsequently the wall thinning indicator was derived from the impingement erosion model. Moreover, the variation of the normal velocity on the inlet impingement plate and upper drain baffle plate with the inlet water flow and unit load was simulated and analyzed. Results show that the model proposed could intuitively and accurately predict the erosion location on the impingement plate and the shell wall. The prediction results agree well with actual erosion sites in the power plant, which therefore may serve as a reference for safe and economic operation of high pressure heaters.
  • Research on Energy Efficiency Improvement of a Turbo-Generator Stator Drying Room
    Wang Lazhen, Pan Weiguo, Wang Wenhuan, Qin Ling, Pan Yanxing
    2019, 33(5): 309-313,319.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To improve the energy efficiency of a turbo-generator stator drying room, the energy consumed by each part of the drying room was tested on site, while the flow field in the drying room was optimized through numerical simulation. Results show that the heat loss due to radiation of equipment and pipes takes the dominant position, accounting for 14.18% of the total input energy, which could be reduced by 5.23% through the improvement of thermal insulation measures. Reducing the area of the main hot air nozzle and increasing the speed of the main hot air entering the drying room can make the temperature distribution relatively uniform between the front and the rear wall of the drying room, thus forming a vortex in the central region to further increase the heat exchange between the stator and the airflow by 4.75%.
  • Influence of Surrounding Buildings on Heat Transfer Performance of a 660 MW SCAL Indirect Dry Cooling Tower
    Li Huijun, Yang Changgen
    2019, 33(5): 314-319.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A three-dimensional numerical model was established for a 660 MW SCAL indirect dry cooling tower with and without surrounding buildings, and subsequently numerical simulations were conducted at different environmental wind speeds with FLUENT software. Results show that both the mass flow rate and heat-transfer rate decrease first and then increase with the rise of wind speed, and their minimum values appear at the wind speed of 12.0 m/s. In the case with surrounding buildings, the maximum changes of above two rates appear at the wind speed of 20.0 m/s and 5.5 m/s, respectively, while their minimum changes appear at the wind speed of 0 m/s.
  • Features and Application of a Supercritical Carbon Dioxide Closed Brayton Cycle
    Xu Qian, Chen Hongxi
    2019, 33(5): 320-324,330.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the supercritical carbon dioxide (S-CO2) closed Brayton cycle as an object of study, an analysis was conducted on the fluid properties, cycle features and cycle advantages. Results show that the S-CO2 closed Brayton cycle has broad application prospects in the fields of coal-fired power generation, nuclear power generation, concentrated solar power generation and waste heat utilization, etc.
  • Research on Modeling and Simulation of a Micro Gas Turbine Based on MATLAB
    Zhong Yafei, Yan Weidong
    2019, 33(5): 325-330.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    GUI programming of MATLAB software was used to establish an integral model for the micro gas turbine, including the inlet pipe, compressor, heat exchanger, combustor, turbine and generator, as well as the parameter conversion module. On above basis, the power generation capacity and efficiency of the micro gas turbine were calculated at different inlet temperatures and altitudes, while the measured parameters were converted into corresponding values under standard atmospheric condition, such as the power generation and torque, etc. The simulation results were then compared with the standard data of a C30 micro gas turbine. Results show that the model has a high calculation accuracy, which could be used to study the influence of environmental condition on the performance of a micro gas turbine, and to evaluate its performance, thus laying a solid foundation for optimal design of new type gas turbines.
  • Optimization of Flow Field Uniformity in a Boiler Cold Air Duct Based on Numerical Simulation
    Zhu Shaochun
    2019, 33(5): 331-334.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To improve the uniformity of seriously uneven flow field in the cold air duct of a 330 MW oil- and gas-fired power plant, which leads to the problem that the temperature rise of secondary air is lower than the design value and the vibration of cold air duct is obvious, numerical simulations were conducted to calculate and compare the flow field in different cases by arranging deflectors at different elevations and angles at the outlet of the forced draft fan. Results show that when the deflector is installed at the elevation of 953 mm and the angle of 10°, the backflow at the inlet of air heater would reduce to 12.5% of the total flow area, when the uniformity of flow field in the air duct would be significantly improved.
  • Effects of Frequency and Temperature of PWHT on Microstructure and Properties of P91 Steel
    Zeng Fanwei, Xie Xiaoyuan, Zhang Xuexing, Zeng Hui, Gao Miaomiao, Chen Lijun
    2019, 33(5): 335-339.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By means of mechanical property tests, optical microscopy (OM) and scanning electron microscopy (SEM), the effects of frequency and temperature of post-weld heat treatment (PWHT) on microstructure and properties of P91 steel were investigated. Results show that, after 5 times of PWHT at 760℃, compared with the base metal in delivery status, the aging behavior of treated P91 steel is not obvious, which still keeps the structure of lath martensite, with slightly lowered strength and hardness. When the PWHT temperature gets above 790℃, the martensite decomposes, the carbide aggregates and grows, and the aging of microstructure intensifies with the rise of PWHT temperature, leading to obviously reduced strength and hardness of the steel, which therefore can not satisfy the requirements of relevant standards.
  • Analysis and Treatment of Increased Resistance in a Single-tower Double-cycle Desulfurization System
    Liu Entian, Xu Jiang, Zhao Zhifa, Xue Xiaoyu
    2019, 33(5): 340-343.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at the operation conditions of the single-tower double-cycle flue gas desulphurization (FGD) system for a ultra-supercritical double-reheat unit, an analysis was carried out on the limited load capacity of the unit caused by increased differential pressure and blockage in its mist eliminator, while an introduction was presented to the specific operational adjustment, on-line pickling and shutdown inspection for the mist eliminator, following which, detailed countermeasures were put forward and taken, with good effectiveness achieved.
  • Discussion on EMC Test Strategy for Motor-operated Valves of AP1000 Nuclear Power Plants
    Chen Yunlong, Xu Fen
    2019, 33(5): 344-347.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is being presented to the test items, test methods and performance criteria of the electro-magnetic compatibility (EMC) test for motor-operated valves in AP1000 nuclear power plants, and subsequently functional verifications are carried out after the EMC test. In addition, EMC tests for other types of valves are simultaneously discussed, while suggestions on the items, sequence and methods of EMC tests are put forward for the motor-operated valves in nuclear power plants.
  • Blockage Analysis of the Water Cooling System for the Generator Stator in a 660 MW Supercritical Power Unit
    Cao Nong
    2019, 33(5): 348-353.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the blockage and corrosion problem occurring in the hollow copper conductor of No.1 generator stator in a 660MW unit, an analysis was conducted on the causes and treatment options based on field operation data, after which, following operation conditions are recommended, such as low pH value (6.5~7.0), low conductivity (<1.0 μS/cm) and high oxygen concentration (dissolved oxygen >2 000 μg/L), etc., when low copper corrosion rates and high water quality could be obtained.
  • Optimization and Adjustment on the Air Distribution Mode of a 1 000 MW Swirl-opposed Firing Boiler
    Fang Junting, Han Lei, Ma Qilei
    2019, 33(5): 354-357.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problems occurring in the swirl-opposed firing boiler of a 1 000 MW ultra-supercritical unit, such as high emission mass concentration of CO, high temperature of exhaust gas and low efficiency of boiler, etc., optimization and adjustment were conducted on the air distribution mode based on simulation analysis and on-site test results, considering structural features of the boiler secondary air box. Results show that at the unit load of 1 000 MW and 750 MW after optimization, the CO emission reduces from 2 822 mg/m3 and 1 795 mg/m3 to 146 mg/m3 and 106 mg/m3 respectively, with exhaust gas temperature being reduced by 11.7 K and 12.5 K, and boiler efficiency being increased by 1.34% and 1.19%, indicating obvious optimization effectiveness of the boiler.
  • Optimization on the LP Heater Drainage System of a 1 000 MW Thermal Power Unit
    Chen Bingbing, Li Lijun, Cheng Zutian
    2019, 33(5): 358-361.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By analyzing the problems existing in the final low-pressure (LP) heater drainage system of a 1 000 MW ultra-supercritical unit, a new type of self-balancing water-sealing LP heater drainage system was proposed. Through theoretical research and engineering application of the new LP heater drainage system, its working principle and implementation method were elaborated, while a summary was carried out on the empirical formulas to determine the important parameters for arrangement of the final LP heater combination point, the drainage cooler and the drainage riser, etc. The new system proposed may serve as a reference for the design and layout optimization of the LP heater drainage system in 1 000 MW units, which has broad application prospects.
  • Optimization and Application of the AGC System in a CFB Unit
    Tong Hongzheng, Cheng Yingguan, Pei Jianjun, Chang dongwu, You Changfu
    2019, 33(5): 362-365.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem that the automatic generation control (AGC) system of 2×330 MW circulating fluidized bed (CFB) boilers could not be able to run in auto mode, disturbance tests were conducted on the boiler primary air and secondary air considering the operation features of the combustion control system. Based on analysis of the test results, dynamic response characteristics of the main steam pressure and bed temperature were obtained, and subsequently the control strategy was optimized by bed temperature trim, covering the proportion of the primary to secondary air flow. Results show that the AGC system is now able to operate automatically after the new control schemes are applied, which helps to achieve stable and reliable operation of the unit significantly.
  • Application of LP Cylinder Cutting Technology in a 600 MW Steam Turbine Unit
    Wang Qi, Liu Yanan, Liu Wangkou
    2019, 33(5): 366-370.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the application of low pressure (LP) cylinder cutting technology in a 600 MW unit. After the low pressure cylinder was switched off, a safety checking was conducted on the unit, following which, retrofit schemes were discussed in detail, covering the connection pipe, cooling steam bypass system, steam turbine property, and the thermal control system, etc. Moreover, an analysis was carried out on the performance of the unit. Results show that the unit has realized thermoelectric decoupling after cutting the LP cylinder, when the coal consumption of power supply is greatly reduced and the heat supply economy is obviously improved.