Power Equipment

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  • 2017 Volume 31 Issue 4
    Published: 15 July 2017
      
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  • Model Identification of Thermal Process Based on Modified Hybrid Particle Swarm Optimization
    Chen Zhen, Wang Mingchun, Zhang Yufei
    2017, 31(4): 223-226.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of basic particle swarm optimization algorithm that is easy to fall into the local optimal solution, a modified hybrid particle swarm optimization algorithm was proposed based on the genetic algorithm and simulated annealing algorithm, i.e. introducing the selection, crossover and mutation in the genetic algorithm and the particle swarm optimization in the simulated annealing mechanism, which is able to maintain the diversity of particle swarms and improve the global evolution speed. Application results show that the modified hybrid particle swarm optimization algorithm has better effects compared with the basic particle swarm optimization algorithm.
  • Analysis on Inlet Flow Field of Dust Collector in a 660 MW Power Unit
    Zhao Dazhou
    2017, 31(4): 227-229.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The distribution of inlet flow field in dust collector of a 660 MW unit was studied by numerical simulation. Results show that the flue gas was not distributed uniformly in two columns at the inlet of dust collector; the flue gas amount in column A was about 1.2 times of that in column B. The flue gas amount can be balanced by adding a baffle about 1 300 mm long at the intersection of the two columns, when the pressure drop of system would be increased by 20 Pa, with improved uniformity of the fly ash.
  • Fault Analysis of a Fan after Variable Frequency Retrofit
    Zhang Liliang, Wang Qinghua, Li Dongdong, Yang Jiangang
    2017, 31(4): 230-233.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To handle the shaft damage accident occurring to a 1 000 MW unit after taking variable frequency retrofit on its axial flow fan, the fault causes were studied by setting up a mechanical model for the shaft system and by performing field tests on the shaft torque. Results show that at certain rotating speeds, if one of the harmonic components is consistent with the natural torsional frequency of shaft, then torsional resonance would occur to the transmission shaft, which have great impacts on safety operation of the unit.
  • Analysis and Comparison on Combustion Monitoring System of Overseas Gas Turbines
    Yang Zhipeng, Yang Jingqi, Zhang Weijie
    2017, 31(4): 234-239.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A brief introduction is presented to two methods of gas turbine combustion monitoring and protection, i.e. exhaust temperature distribution monitoring and combustion dynamic pressure monitoring, together with a description on their working principles. Taking the F class gas turbine from GE, Siemens and Mitsubishi as an example, a comparative analysis is made to the system layout of combustion monitoring and protection as well as to their alarming logics, and subsequently the characteristics of each system are obtained, which may serve as a reference for research and development of domestic gas turbines.
  • Analysis on Active Power of a Three-phase Half-wave Controlled Rectifier with Resistor-Inductor Load in Intermittent State
    Wang Shuai, Zhou Yunhua
    2017, 31(4): 240-244,249.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To accurately measure the active power of a three-phase half-wave controlled rectifier, an algorithm was proposed through theoretical analysis by taking the periodically intermittent state of load current as an object of study, which was proved to be effective and accurate via verification with simulation results.
  • Experimental Research on Thermal Performance of a Trough Solar Collector
    Li Ke, Kuang Rao, Qiu Qiuling
    2017, 31(4): 245-249.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the thermal performance of a trough solar collector, a series of studies were carried out so as to design the experimental system for outdoor thermal performance test, and to analyze the operation characteristics of the collector by measuring its operation data under actual working conditions. Results show that both the water flow rate and solar radiation intensity have great influence on the thermal efficiency of the collector, which would reduce to some extent with the maximum deviation of 3.1% when the flow rate increases from 0.32 m3/h to 0.65 m3/h. The thermal efficiency varies in the same trend of solar radiation intensity, and the maximum value may get up to 46.6%.
  • Design and Type Selection of Low Calorific Value Waste Incineration Power Units
    Wang Yungang, Yu Fei
    2017, 31(4): 250-253.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the combustion problem occurring in a specific example of low calorific value waste incineration power unit, an analysis was conducted according to the differences in storage and transportation of low calorific value wastes collected in different regions and seasons, after which matters needing attention were proposed for the process design and equipment selection of main systems for waste incineration power units to be constructed in fourth-tier cities and small towns.
  • Study on Reliability Assessment of Safety Injection System in Nuclear Power Plant
    Shen Wei, Lu Bin, Yang Bingqing, Jing Yajie, Zhu Xiaoliang
    2017, 31(4): 254-258.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the reliability of safety injection system, an equipment reliability calculation model was built for the system based on historical operation data of existing nuclear power units and with combination of numerical methods such as neural network, maximum likelihood estimation and support vector machine, so as to assess the reliability of the system by calculating the reliability of relevant equipment using reliability mathematical models. The feasibility of the method was verified by comparison with real-time operational data of nuclear power plants, which may serve as a reference for reliability assessment of safety injection systems in nuclear power plants.
  • Seismic Analysis of a Cartridge for Nuclear Power Plants
    Liu Yajuan, Wang Jingxi, Pan Cong, Chi Hao, Li Jiaqi
    2017, 31(4): 259-262,266.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A three-dimensional calculation model was established for a cartridge of nuclear power plant by FEA software ANSYS, with which seismic analysis was conducted on the cartridge structure under the action of gravity, pressure and SSE loads using equivalent static loading method on the basis of model analysis. Meanwhile, stress combination and evaluation were carried out under D stress limits according to requirements of ASME section Ⅲ. Results indicate that the design of related cartridge meets the requirements of ASME section Ⅲ.
  • Research on Timer Interruption in Semi-digital Relay Protection of Nuclear Power Plants
    Wang Xuekui, Zhang Jie, Hu Wangxiong, Qiu Yu, Yang Jianrong
    2017, 31(4): 263-266.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the timer interruption problem occurring in the operation of a semi-digital relay protection system of Taishan Nuclear Power Plant, following items were performed, such as testing the action status of the relay protection system during timer interruption periods, analyzing the effects of timer interruption on the digital relay protection, finding out the possible cases of out of step sampling based on analysis of the mathematical relations among the modified step size of timing device, the jumping time of merging unit and the error of GPS device, after which several solutions were given, considering the current design of the timer and the frequent alarms of the relay protection system, which may serve as a reference for final settling of the fault and for further improvement of the design.
  • Formation Mechanism of Water Droplets in Exhaust Chimney of Power Plants
    He Xiong, Jiang Lei, Zhen Wenlong
    2017, 31(4): 267-271,275.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the formation mechanism of "misty rains" in thermal power plants, including the internal and external influencing factors. Based on analysis of operation data obtained at different environmental temperatures and wind speeds, the primary and secondary causes leading to the formation of "misty rains" were found, to which corresponding countermeasures were proposed.
  • Vibration Diagnosis and Disposal of a 660 MW Turbo-Generator Unit During Hot Starting
    Li Wantao, Fu Xingjun, Xing Haibo, Deng Minqiang, Cai Ming
    2017, 31(4): 272-275.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of excessive shaft vibration near the first bearing of a 660 MW unit during hot starting process, the vibration characteristics were analyzed when the turbine was accelerating, decelerating or at a constant speed, after which the fault was found to be caused by rub-impacts due to too small expansion difference in the case of hot starting. By adjusting the operation parameters and shortening the speed-up time, the unit succeeded in reaching rated speed and the vibration was kept within reasonable range. This may serve as a reference for dealing with such kind of faults.
  • Retrofit on Burners of a Supercritical Boiler to Reduce its NOx Emission
    Li Xiaomin, Wang Lijun
    2017, 31(4): 276-279,285.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To satisfy the NOx emission requirement of a certain supercritical boiler, a retrofit scheme was proposed by adopting air-staged low-NOx combustion technology, where super-concentrated pulverized coal is used, and all burners are of the swirl wear-resistant ceramic type, while the overfire air burners swing up and down. Operation results show that the NOx emission of boiler has been greatly reduced after the retrofit.
  • Single-row Layout Application of Air & Flue Gas System for 660 MW Ultra Supercritical Units
    Xi Liqiang, Zhang Ling, Li Haiyan
    2017, 31(4): 280-285.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the single-row layout feature of the air & flue gas system in two 660 MW ultra supercritical coal-fired units, while a comparison is made with that of double-row layout system. Results show that the single-row arrangement of air & flue gas system is simpler and its control and operation are easier.
  • Research and Application of Energy-saving Primary Air Adjustment Technology for 1 000 MW Coal-fired Boilers
    Yang Biao, Yang Bo, Zeng Biqun, Chen Shaohua
    2017, 31(4): 286-289,294.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on experimental results, an analysis was conducted on the control features of primary air in a 1 000 MW coal-fired boiler, after which a energy-saving primary air adjustment technology and an optimal load distribution mode among various coal mills were proposed under different load conditions, while an adjustment optimization was carried out on the coal-air ratio of coal mills according to actual working conditions, thus achieving good economic effects.
  • Analysis of Uneven Temperature Distribution on Symmetric Areas of a Self-aligning Elliptical Bearing
    Zhao Guoqin
    2017, 31(4): 290-294.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the tripping problem of a steam turbine caused by uneven temperature distribution on symmetric areas of the self-aligning elliptical bearing or by too high temperature in local areas, a quantitative analysis was conducted on the characteristics of the bearing. Results show that the failure was caused by lowered self-aligning ability of the bearing, uneven contact between the bearing and rotor, uneven load on symmetric areas, or by uneven flow of lubricating oil.
  • Upgrading Retrofit on Servo System of Steam Turbines
    Rao Feng, Xing Mingcheng, Mo Wenjie, Xie Tengfei
    2017, 31(4): 295-299.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of frequent malfunctions existing in the original servo valve of a steam turbine, a dual redundant servo system was introduced to the end of the original system, breaking through the limitation of the original system that is not compatible with other DCS systems, overcoming the restrictions of swinging installation of hydraulic actuator (swing cylinder), and simultaneously designing a set of position feedback assembly, thus solving the problems in the original system, such as high fault rate of servo valve and frequent damages of LVDT, etc.
  • Design and Application of Automatic Impulse System for a Feed-water Pump Turbine
    Luo Peiquan, Zhang Longming, Chen Xilong
    2017, 31(4): 300-304.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To secure the safety operation of a power unit, an introduction is presented to the design scheme of its automatic impulse system for the feed water pump turbine, together with an analysis on the control range, key start-up procedures and key design points of the system, which has been proved to be reasonable by actual applications.