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Table of Content

    25 July 2018, Volume 40 Issue 5
    Study on evaporation characteristics of brine in spray evaporation process at ambient temperature
    ZHAO Baohua1, GAO Ran2, WEN Jiaqi2, YI Zuyao1, HAN Zhengfei1
    2018, 40(5):  1-7. 
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    China encourages “nearly zero discharge” of industrial wastewater, and advanced treatment of brine is of great deep concern. Desulfurization wastewater, mining wastewater and other industrial wastewater can be processed by spray evaporation technologyat ambient temperature. On the selfbuilt outdoor test beds for spray evaporation test, the evaporation rate of brine was measured and the characteristics of evaporation products were described by scanning electron microscope (SEM). Smaller atomized particulars lead to a larger evaporation rate. When the particle diameter is over 500μm, decreasing the size of particular has small effect on evaporation rate. Smaller salinity leads to a larger evaporation rate, but the difference is slight. The spray evaporation rate has an approximately linear positive correlation with the wind velocity, exponential positive correlation with temperature, and a negative correlation with the relative humidity. The wind velocity is the decisive factor of the spray evaporation rate as wind velocity is large. When the relative humidity is over 90%, humidity is the decisive factor. When the temperature is less than 15℃, the temperature is the main factor . The mechanical atomization rate of the test is about 4~12 times of natural evaporation rate.At the same time, it is noted that there is wind loss in spray evaporation rate, and measures should be taken to avoid the secondary pollution caused by water of high salinity.
    Analysis and improvement on logic design of G60 generator  protection
    LIU Fang,WANG Dongya
    2018, 40(5):  8-12. 
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    There are many protection changes on GE generators since #3 and #4 units of Zhuhai Jinwan Power Company Limited got into operation in 2007. G60 protection on generators includes 500kV switches full stop protection, CT disconnection, loss of excitation protection and wave recording startup. The problems of secondary circuit wiring and logic design are analyzed and improved to optimize the protection function of generator, which guarantees safe production.
    ACC design optimization for gas turbine combined cycle units
    QIU Yonggang
    2018, 40(5):  13-16. 
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    According to the basic principles of heat transferring,it creates a mathematical model of heat transferring area and power consumption of ACC affected by initial temperature difference (ITD) and head wind velocity. Taking an Fclass oneplusone CCPP as an example, it calculates the influence of ITD and head wind velocity on net output and ACC heat transferring area of power plant and obtains the optimized ACC design parameters.
    Research on status and application prospect of locally installed protection of intelligent substation
    LI Liangyu, TANG Baofeng, ZHAO Xianlong, ZHANG Ji, ZHENG Ziyao
    2018, 40(5):  17-20. 
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    On the basis of the status quo of the locally installed protection,the scheme of locally installed protection is proposed.The characteristics of singlemaster scheme and fullmaster scheme are compared for crossinterval protection. It focuses on singlemaster scheme of transformer protection and the fullmaster scheme of busbar protection.The key technical issues of locally installed protection are pointed out.Current progress of research and development of localized protection devices is summarized and the application scenarios for locally installed protection is prospected.
    Research on risk assessment and information management of boiler heating surfaces
    ZHAO Xiaopeng1, ZHAO Fei2, NI Yongzhong2
    2018, 40(5):  21-24. 
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    The main reason for unplanned outage is the bursting and leakage of heating surfaces of power plant boiler. According to the status quo of passive inspection and maintenance on power plant anti-wear and explosion proof, a concept of digital management on boiler antiexplosion and antiexplosion work is put forward. Wall temperature of boilers are analyzed, assessed and graded from various aspects. The risk assessment model of heatingsurface pipe is established. The equivalent creep lifetime loss caused by overtemperature is introduced into the evaluation model. Combined with offline testing data, the risk level of the heatingsurface tube is amended dynamically, which can improve the assessment reliability of the risk indicators.
    Multivariable modeling of the main steam temperature based on field data and PCA
    HOU Xiaoning
    2018, 40(5):  25-29. 
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    As the main steam temperature system is a multivariable and strong coupling system, a large number of field operational data is collected. Through principal component analysis(PCA),five main variables are extracted from 11 procedure variables as the input of the main steam temperature system. Simultaneously, the mechanism modeling, experimental modeling and intelligent optimization algorithms modeling are combined. Finally, the multipleinput singleoutput multivariable model is established by using the field data. This solution solves the problem of frequent and largescale step disturbance tests in which it is not allowed or cannot to get to the productive site. It overcomes the uncertainty of the range of initial values and model structure for multivariable intelligent optimizing, and established a multivariable model that can be used for studying main steam temperature system control.
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    FU Xueliang, LI Dejun
    2018, 40(5):  30-32. 
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    Control strategy on steam temperature of 1000MW double reheat units
    HU Zunmin,YU Guoqiang,SHU Jianjun,ZHANG Tianhai
    2018, 40(5):  33-37. 
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    Taking 1000MW double reheat units of Guodian Taizhou Power Generator Company Limited, it introduce the control principle of  superheated steam, first and second reheat steam temperature for tower type double reheat boiler. Analyzing steam temperature’s control logic on proportion, integral and derivative (PID), it proposes a control logic for steam temperature regulating equipment of 1000MW double reheat units which can provides reference for unit control logic configuration and optimization of double reheat units.
    Refinement and analysis on alarm information system during the gas turbine SFC startup
    GU Yiyang1,XIAO Liming2
    2018, 40(5):  38-40. 
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    Gas turbine generally adopts the static frequency converter (SFC) as startup mode of electric drive. The SFC system has a complex logic system, and its faults affects the startup and operation of the whole unit. Mastering the principle of SFC system and improving alarm information system can speed up the problem solving of electric driving, save the time for the paralleling to the grid, and ensure the normal start of the unit. Through practical tests and exploration a solution optimization scheme is put forward to solve the general problems in SFC operation.
    Analysis and regulation on vibration of high temperature and high pressure pipe
    2018, 40(5):  41-44. 
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    In order to solve the problem of excessive vibration at hot reheat steam pipe, field investigation, vibration measurement and data processing on pipe vibration are carried out to analyze the vibration characteristics of the pipeline.  It points out that regulation on vibration should be made from three dimensions which are eliminating the turbulence force, improve the piping vibration characteristics, and maintain the level of primary stress and secondary stress level as far as possible. It puts forward a scheme to install vibration damping device on the premise of ensuring qualified stress of pipe system. The pipeline vibration is effectively controlled after treatment.
    Analysis on power reliability of 600MW and above coalfired units
    HAN Qin, FAN Huijian, LIU Zhanli
    2018, 40(5):  45-49. 
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    To improve operational reliability of 600MW and above coalfired units ,it analyzed the factors affecting the reliability of 600MW and above coalfired units of 2016. It is concluded that the poor quality of maintenance, poor quality of products and fuel affection are the main reasons for the unplanned outage of the units, among which the poor quality of maintenance is the dominant reason. Unplanned outages caused by boilers accounted for the largest proportion of unplanned outages caused by the three main equipment. Blockage, steam leakage, oil leakage, water leakage, great vibration, jam, abrasion, high temperature, corrosion, cracks and so on, are the main factors affecting the reliability of auxiliary equipment.
    An improved phrase selection device of double circuit lines on the same tower
    ZENG Xianhua
    2018, 40(5):  50-52. 
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    Analyzing the faulty features of the double circuit lines on the same tower and the existing conventional mutation of phase selection device that accrues in crossline fault, a new method is proposed to deal with phrase selection based on mutant phase selection of double circuit lines. After the fault of system, phase selection device should adjust the proportional relation between the offset voltage and the voltage mutation according to the magnitude of the fault current, recognize the simple fault in internal area and complex fault in external area, input phase selection device adaptively. In view of crossline fault of double circuit lines, a new phrase selection method is put forward, which effectively solve the mistaken choice of mutation phrase selection device while dealing with the crossline fault, improve the security of the power system operation, stability and reliability of the transmission.
    Keywords:direct air cooling; operation and adjustment; antifreezing
    REN Liang
    2018, 40(5):  53-55. 
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    The antifreezing method of 330MW direct air cooling cogeneration unit operating in winter, especially in the extreme cold weather, is still in experience accumulation and exploration period. According to the existing operation mode,  continuous optimization and adjustments,such as raising the back pressure of units, starting the standby vacuum pump and exit isolation column, are made to meet the winter antifreezing requirements and overcome the code winter.
    Cause analysis and treatment of high moisture content of gypsum in 1050MW unit
    CHEN Li1,WU Chunchao2
    2018, 40(5):  56-57. 
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    Aiming at the problem of high moisture content of gypsum in a 1050MW unit, the influence factors such as the quality of limestone powder, the quality of the absorber, the vacuum pump, the vacuum degree of vacuum belt dewatering machine and the solid amount in underflow of the swirl are investigated. The main reason to determine the high water content of gypsum is the low installation precision of vacuum belt dewatering machine, and the cracks in gypsum results in the reduction of vacuum degree. The secondary reason is that the pH of the absorber slurry is high and the gypsum crystal is rare. By taking corresponding measures, the high water content of gypsum is solved.
    Optimized design of automatic generation control system at plant level
    DAI Xihui
    2018, 40(5):  58-60. 
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    In order to achieve the economic distribution of load among different units in plant, Guangdong Honghaiwan Generation Company Limited launch a set of external plant level automatic generation control (AGC) system. AGC command turns from the original load command for single unit to load command for the whole plant. After acceptance of load command for the whole plant, load optimization calculation is made by plant level AGC server.  It introduces the construction of plant level AGC system, structure and process of software at plant level, and summarizes the key designing points of AGC system. After the operation of the system, accuracy of every channel, the load command distribution, load change rate and response to primary frequency modulation can satisfy the requirements of grid. The load distribution right of each unit is obtained by the plant side.
    Causal analysis on the carbon brush cord peeling off from the 390H generator excitation
    NIU Zhifeng
    2018, 40(5):  61-62. 
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    It introduces the structural characteristics of 390H generator excitation carbon brush. Comparing and analyzing the original parts and replaced parts from structures and craftsmanship, it points out that ordinary carbon brush cord embedding process is not applicable to this type of carbon brush, which is the main cause of carbon brush cord peeling. It can be taken as reference for selecting carbon brush and operational maintenance for generator excitation.
    The method of energy conservation and environmental protection by generating electricity with falling water of cooling tower
    YU Dechao1, WU Weiyu2
    2018, 40(5):  63-67. 
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    It introduces a reconstruction scheme of cooling tower in thermal power station. It adopts and combines the existing materials and devices to utilize the energy of falling water of cooling tower. It solves the environmental problem of noise, prevents the anticrosswind and reuses cooling water, which increases the efficiency of the device and the cooling effect of cooling towers.
    Analysis and countermeasure of main factors affecting comprehensive water consumption rate of Silin Power Plant
    HOU Guangqiang
    2018, 40(5):  68-69. 
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    The water consumption rate of Silin Power Plant,Guizhou Wujiang Hydropower Development Company Limited is relatively high. The external environment of unit operation is analyzed from the function of power plant in power grid, reservoir operation characteristics and relationship between upstream and downstream reservoirs. The main factors affecting water consumption rate are analyzed from the internal environment which includes adjustment of time between overhauls, load fluctuation per unit and single unit operating condition. It takes measures such as the dynamic control of reservoir water level, the improvement on the accuracy of small flood forecast and the optimizing the starting sequence of units, to effectively reduce the water consumption rate of power plants.
    Design and application of water level measurement system for boiler drum of waste heat boiler in distributed energy station
    DONG Shumei1, YU Li1, DU Juhu2
    2018, 40(5):  70-72. 
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    The reliability of water level measurement signalof waste heat boiler drumin regional distributed energy station is directly related to the safe operation of waste heat boiler and steam turbine equipment .Therefore,the water level measurement system of waste heat boiler drum is one of the most important system for thermal measurement. Taking the water level measurement to a highpressure drum of double pressure waste heat boiler as an example, the key designing points of water level measurement system are analyzed and studiedfrom configuration of measuring instrument for water level of drum, drum instrument measuring principle, the configuration and the corresponding correction method for balance container of differential pressure type level gauge, the drum water level control and processing of protective signal.
    Brief analysis on the development and design of building gas distributed energy supply system
    YU Li1, 2
    2018, 40(5):  73-74. 
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    Natural gas distributed energy has developed rapidly in China in recent years. It analyzes the factors that influence the economic efficiency of building gas distributed energy supply system and puts forward the suitable development conditions. At the same time, the key designing points of building gas distributed energy supply system, the requirements for energy station location and layout are put forward.
    Analysis of high voltage fault of super capacitor in wind turbine pitch system
    LI Ya’nan
    2018, 40(5):  75-76. 
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    :Analyzing pitch capacitor’s high voltage fault in Vensys pitch system of a wind farm in Inner Mongolia. Analyzing the cause of fault and check them item by item, it is found out that while taking manual pitch control, the output voltage of pitch capacitor voltage monitoring module is less than 54V after 3s .The voltage return to normal after terminating the pitch system . After replacing the supercapacitor, the unit return to normal operation.