Power Equipment

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  • 2016 Volume 30 Issue 3
    Published: 15 May 2016
      
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  • Research on the Effect of Water Distribution by Sectors of SCAL Indirect Air-cooling Towers
    Wei Hongqi, Sheng Bo, Geng Biao, Wu Xiaolin
    2016, 30(3): 141-147.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The flow and heat-transfer performance of an indirect air-cooling tower were studied under crosswind conditions using three-dimensional numerical model. Results indicate that under the conditions that all other inlet parameters keep constant, the total heat dissipating capacity decreases as the crosswind speed grows, due to the great reduction of heat dissipating capacity in lateral sectors because of the flow around circular cylinder, and that the increase of heat dissipating capacity in windward sectors is not high enough to compensate the dissipating loss in other sectors. According to the characteristics of heat distribution in various sectors, a new scheme is proposed for wind protection, i.e. the circulating water is distributed on the basis of the ratio of heat release in corresponding sectors, which, to some extent, can alleviate the impacts of crosswinds on heat dissipation of the indirect air-cooling tower through reasonable ventilation.
  • Numerical Simulation on Thermal Performance of Straight-through Evacuated Collector Tubes
    Qiu Qiuling, Kuang Rao, Yang Fan, Liu Jingjing
    2016, 30(3): 148-152.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The complex coupling heat transfer process of collector tubes was simulated using Fluent software based on the heat transfer model established under the boundary condition of non-uniform heat flux, following which the simulation results were verified by comparison with experimental data. Meanwhile, the effects of irradiation intensity, heat-transfer fluid velocity and inlet temperature on the circumferential temperature distribution around absorber tubes were analyzed under the boundary condition of non-uniform heat flux. Results show that the axial distribution of heat flux is very uneven and the circumferential temperature difference around absorber tubes is up to 74.5 K. Larger temperature difference would bring thermal stress in the collector tube, and when the stress exceeds the yield strength of collector, it would cause damage to the tube, thus reducing its service life.
  • Design of Hydraulic Simulation Test Models for CAP1400 Reactors
    Ding Zonghua, Liu Bin, Lin Shaoxuan, Zhang Ming
    2016, 30(3): 153-155,159.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    As a test facility, the hydraulic simulation test model was designed for CAP1400 reactors to verify the core inlet flow distribution and to obtain the hydraulic information (pressure drop and velocity) from the inlet piping to the outlet piping, to which a detail introduction was made with focus on the model scale, model similarity criterion, model design principles and main model features, which may serve as a reference for design of similar test models.
  • Investigation on Qualification Method for Radiation Aging of Nuclear Equipment
    Yang Xiao, Zheng Kaiyun
    2016, 30(3): 156-159.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the radiation environment in nuclear power plant and the damage mechanism of radiation to the equipment, together with a description to the radiation aging qualification for nuclear safety-related equipment and the radiation aging test facilities. As an example, the qualification method for reactor electrical penetrations is discussed, covering the calculation, analysis and test process of radiation aging qualification.
  • Application of Commercial-grade Dedication in Procurement of AP1000 Polar Cranes
    Zhang Ying, Jiang Zhongming
    2016, 30(3): 160-163,167.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To overcome the difficulties lying in China's nuclear power industry that few nuclear power equipment suppliers are able to provide nuclear safety related equipment or components, the dedication strategy of commercial grade items (CGI) pioneered in United States was introduced, which was applied in the procurement of AP1000 polar cranes in Sanmen and Haiyang Nuclear Power Plant, with focus on detail analysis of the CGI dedication process concerning the representative mechanical and electrical safety related components in AP1000 polar cranes. Test results verify that the nuclear safety related components procured through dedication of commercial-grade items are able to meet relevant requirements, which therefore may serve as a reference for procurement of nuclear safety related equipment or components in China.
  • Design of the Main Hoist for Refueling Machine in a CAP1000 Project
    Liu Jianwen
    2016, 30(3): 164-167.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Through deep analysis on the function and principle of the main hoist for refueling machines of AP1000 nuclear power stations, an innovative design was carried out to the main hoist for refueling machines of a CAP1000 project, with improvements on the maintainability and economy, so as to achieve localization of the refueling machines.
  • Materials Selection for Boiler Superheater of 700℃ Ultra Supercritical Units
    Wang Chongbin, Zhu Yufeng, Wang Yu, Xu Ruoyu, Qin Sheng, Zhu Geng
    2016, 30(3): 168-172.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The properties of small-diameter tubes or pies made of following candidate materials were introduced for the superheater of 700℃ ultra supercritical boilers, such as the austenitic stainless steel Sanicro25, Fe-Ni-based alloy HR6W, Ni-based alloy 617mod and Ni-based alloy 740H, etc. Meanwhile, suitable service temperature ranges of tubes Super304H, TP310HCbN, Sanicro25, HR6W, 617mod and 740H for the superheater of 700℃ ultra supercritical boilers were also analyzed, based on which suggestions were proposed for material selection of boiler superheater in 700℃ ultra supercritical units.
  • Research on Low-temperature Corrosion Resistance of 5 Heat Exchanger Tubes
    Wang Zheng, Li Qi
    2016, 30(3): 173-176.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To find a material that is relatively resistant to low-temperature corrosion with high price-to-performance ratios, a field test was conducted in a power plant in southwest China to evaluate the corrosion resistance of materials. Assessment results show that the corrosion rate of materials would accelerate with decreasing fluid temperature, the corrosion rate of steel 1Cr18Ni9Ti is slower than other materials, but steel ND has a higher price-to-performance ratio.
  • Low-NOx Combustion Retrofit of a 75 t/h MT Separated CFB Boiler by Adding the Third Layer of Secondary Air
    Wu Jianheng, Yu Jinshu, He Hongzhou, Zhuang Songtian
    2016, 30(3): 177-182.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By analyzing the main factors influencing the NOx emission of a 75 t/h circulating fluidized bed (CFB) boiler with medium-temperature (MT) cyclone separators, a low-NOx combustion retrofit was conducted by adding the top layer of secondary air to form in total three layers of secondary air, elevating the nozzle height of bottom secondary air, raising the velocity at secondary air nozzles, and increasing the secondary air rate, etc. Results show that after the retrofit, the NOx emission has been reduced from original 180 mg/m3 to 140 mg/m3, thus the total annual reduction of NOx emission would get up to 44.62 t for the two CFB boilers, and the unburned carbon loss q4 would drop by 1.0%~1.5%.
  • Frequency Conversion Retrofit of a Circulating Water Pump for Power Plants
    Chen Zhengjian
    2016, 30(3): 183-187.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To guarantee that the flow rate of relevant circulating water pumps is higher than the minimum requirement and the top of the main pipeline can be filled with seawater after frequency conversion retrofit, operation limits are set through analysis and commissioning tests to secure the safety of related equipment and systems. Meanwhile, optimal operation conditions are found by tests and calculations after frequency conversion retrofit, so that the circulating water system can be operated under the best vacuum condition and become more flexible to the DSS operation mode, thus bringing remarkable economic benefit to the power plant.
  • Cause Analysis of Tilting-pad Bearing Damage in a 660 MW Subcritical Steam Turbine
    Yang Xiaowei, Li Guoming, Xie Cheng, Ma Chao
    2016, 30(3): 188-190,193.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An analysis was conducted to both the structural features of a tilting-pad bearing and the reason of the bearing damage occurring in startup/shutdown of a 660 MW subcritical steam turbine due to abnormal temperatures, which was subsequently found to be caused by overloading at the bottom of the pad, resulting in limited self-aligning capability of the pad and broken oil film at low operation speed, thus leading to the bearing damage. Improvement measures were finally suggested for the bearing and lubricating system.
  • Retrofit on Media Gas-Gas Heater of a Coal-fired Power Plant
    Yin Ge
    2016, 30(3): 191-193.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem that the quality of condensed water got deteriorated when the energy recovery system of media gas-gas heater (MGGH) was put into use after ultra-low emission transformation of the coal-fired power plant, a new retrofit scheme was proposed and implemented concerning flushing and arrangement of the pipeline, which has helped to shorten the processing time, reduce the water consumption, eliminate the blind area and remove the hidden danger in the system when it is flushed.
  • Analysis and Optimization on the Ignition Process of M701F Gas-Steam Combined Cycle Units
    Yan Jindong
    2016, 30(3): 194-196,201.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Through analysis on the gas turbine ignition process, safety measures were summarized to prevent M701F unit from deflagration during ignition period, based on which reasonable purging time was determined according to existing gas turbine standards on the premise of considering the unit safety and economy, while an optimization scheme was proposed for the ignition process.
  • Operation Optimization for the Large Condensate Water Pump in a Thermal Power Plant
    Yang Qunfa, Hou Jianxiong, Huang Biliang
    2016, 30(3): 197-201.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Energy-saving effects and remaining problems of the large condensate water pump in a thermal power plant were introduced after frequency conversion retrofit. For optimization purposes, the water pump was operated at reduced pressures, while the boundary condition of pressure limits was obtained through experimental tests, following which corresponding countermeasures were taken to achieve maximum effects of energy saving. Results show that the pressure in main condensate pipe can be lowered in the mode of reduced pressure operation, when energy-saving effects at low load approach to that at high load, achieving energy-saving purposes under all conditions. Both the condensate water pump and the motor can operate normally at reduced pressures, indicating high operation stability of the condensate water pump.
  • Dual-Redundancy Retrofit of a 600 MW Steam Turbine DEH Servo Control System
    Hu Haijun
    2016, 30(3): 202-205,209.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    According to the design safety principles of a steam turbine DEH servo control system and related standards, a retrofit scheme was proposed for the system redundancy, which greatly reduced the possibility of the turbine valve fluctuations caused by improper configuration of the servo control system LVDT, the servo card or other devices, thus improving the reliability of the turbine DEH servo control system.
  • Feasibility Study on Optimization Retrofit of a Waste Heat Boiler
    Xiang Jianwei
    2016, 30(3): 206-209.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    System configuration and performance parameters of a gas turbine waste heate boiler were introduced under different modes, to which various optimization schemes were proposed. By analyzing the retrofit schemes according to performance parameters and actual layout of the boiler, the one keeping its original deaerating way to supply hot water was eventually adopted.
  • Improvements on Control System for SCR Flue Gas Denitrification of Coal-fired Power Plants
    Ma Lige
    2016, 30(3): 210-214.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the SCR flue gas denitrification technology and its reaction principle, problems existing in traditional method of SCR ammonia injection control were analyzed, to which improvement measures were proposed and taken. Engineering practices have proved that the improved cascade-feedforward control method has a good control performance. On the premise of environmental protection, the denitrification cost of the power plant is reduced, while the automatic input rate of the control system is improved.