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    25 May 2019, Volume 41 Issue 5
    Study on the influence of fresh water drainage on seawater desulphurization system
    中国华电科工集团有限公司,北京〓100070
    2019, 41(5):  1-7. 
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    The desulfurization effective ion mass concentration in seawater directly affects the efficiency of the desulfurization system. The desulfurization effective ion mass concentration of seawater in a coastal coalfired power station in Vietnam is affected by fresh water drainage. In order to meet the desulfurization requirements of the power station, it is necessary to calculate the desulfurization effective ions changing with fresh water drainage. A 2D water flow mathematical model of the project is established. Based on the verification of the model, the HCO3- mass concentration at the water intake of the power station at different periods is calculated and the mass concentration of main desulfurization effective ion of seawater, HCO3-, is analyzed. The research shows that during the maximum runoff period, the fresh water drainage has the most significant effect on the  HCO3- mass concentration at the water intake; during the minimum runoff period, the fresh water drainage has a weak influence on the HCO3- mass concentration at the water intake. The research results can provide a basis for designing seawater desulphurization systems of power stations.
    Research on the application of IOT technology in EPC engineering management
    LI Xuhai1,XIAO Yangming1,ZHAO Xuerui2,ZHAO Yaoli2
    2019, 41(5):  8-12. 
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    As our economy and the urbanization construction is advanced rapidly in recent years, the number of infrastructure, electricity and other projects are increasing.There are numerous high technical,difficult and large projects which are followed by more safety and quality accidents.In addition,diversified investors merging in various financial products bring new difficulties and challenges to project management.At the same time,there are obvious gap between the project site management and functional departments management in home office,which is a shortcoming of current domestic engineering project management.In recent years,the IOT technology flourishes in all walks of life.Various information technology is also taken by engineering project management gradually.As EPC project management faces comprehensive constraints on information from each subject and project dimension,making use of IOT technology to catalyzing all kinds of information in engineering project management and improving the level of project management become the goal of engineering companies.Through the research and exploration of IOT and EPC engineering management,modern information technology can realize engineering goals.
    Exploratory test of  desulfurization additive HZY-1 in wet desulfurization system of coalfired power plants
    WANG Qiang
    2019, 41(5):  13-16. 
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    :Limestonegypsum wet flue gas desulfurization technology is widely taken by coalfired power plants.After desulfurization systems  ultralow emission transformation in domestic power plants, most of the desulfurization systems are of excessive sulfur content,low desulfurization efficiency and poor quality limestone, and the slurry making system can not meet the demand. Additive, act as active agent, can be add into the slurry of wet desulfurization absorption tower, which is beneficial to the dissolution of limestone, the absorption of SO2 in the slurry, and  the efficiency improvement of desulfurization system.On the other hand,the slurry which is of a low pH range can prevent desulfurization devices from scaling and clogging  and maintain the stability of the system。
    Study on flow mixing and equalizing technique of primary air  at inlet of medium speed coal mills
    WANG Zhoujun1,2,LI Xinghua2,TANG Lijun1,DUAN Quansheng2
    2019, 41(5):  17-21. 
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    The measurements of the primary air flow rate and air temperature of medium speed mills in a 600MW unit are usually not accurate.Therefore control systems of boiler load, air flow rate,air temperature and burning load cannot work automatically.By CFD numerical simulations, 3 sets of coldhot primary air flow mixing and equalizing devices are designed.Comparing their currentsharing effects, all the coalhot primary air flow mixing and equalizing devices above can satisfy the measuring requirement on uniformity of flow field and temperature field at the measuring section, can eliminate the vortex, can adjust the deflection of airflow in the rectangle primary air duct, and can make the incoming air direction on the measuring section be vertical to the detecting device. The relative standard deviation of the air velocity and air temperature drop to 6% and 2% respectively.The total pressure losses of primary air are less than 300Pa.The average velocity and temperature at crosssection of scheme 3 is of the smallest relative standard deviation,and its current sharing effect is optimal.
    Research on characteristics and mechanism of transformer fifth harmonic under overexcitation condition
    WANG Zhe,GUO Xiao,XING Wu,HU Bing
    2019, 41(5):  22-27. 
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    The magnetic density of modern high-capacity transformers is large while running. In the case of shortterm overvoltage (overexcitation), the transformer excitation current will surge, which can easily cause the maloperation of differential protection. It is necessary to use the harmonic content of the excitation current to lock the differential protection when the multiple of overvoltage is small. The relationship between the excitation current fifth harmonic and the voltage of the transformer is deduced based on fitting 2 lines of transformer magnetic characteristic with 2 different slopes. Transformer overexcitation model is built by the simulation software PSCAD/EMTDC. The theoretical derivation and simulated waveform are compared, which verifies the correctness of the theoretical formula. It discusses the fifth harmonics locking values for transformer protection under overvoltage conditions.
    Feasibility analysis of 700MW supercritical boiler induced draft fan renovation
    WU Shun,CHEN Shuilin,WANG Lianhai
    2019, 41(5):  28-33. 
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    The power consumption of  No.5 boiler induced draft fan of a 700MW supercritical unit in a power plant is relatively large.When the opening of the induced draft fan reaches 60%, and keeps increasing under heavy load, the current growth rate will be too fast; and the operating oxygen of the boiler cannot meet the targeted value. A thermal test on the No.5 boiler induced draft fan was carried out, and combined with the condition of the flue gas system resistance, the feasibility of reducing the blade of  No.5 boiler induced draft fan rotor is analyzed. It provides data support for No.5 boiler induced draft fan renovation.
    Relationship between the charge of balls and electric machine current of coal mill in thermal power plants
    WANG Chengliang
    2019, 41(5):  34-39. 
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    In order to determine the basis for charging steel balls for the ball mills in thermal power plants during the normal operation,ensure the relative stability of pulverizing capacity of ball mills, reduce pulverizing consumption per unit and optimize the combustion of boilers, the relationship between the charge of balls and current of ball mills is studied by experiments.The experimental data analysis determines the relationship between the mill current and the charge of steel ball, predicts the optimum charge of balls and puts forward the way and guidance of charging steel balls during operation of coal mill.
    Implementation scheme for local protection  outdoor installation based on quasi twoterminal prefabricated connection
    CHEN Dong1,2,LI Yuping1,2,CHEN Qi1,2,ZHANG Wei1,2,HU Bing1,2,WANG Sheng1,2
    2019, 41(5):  40-45. 
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    In order to make full use of the miniaturization, standardized interface and plugandplay of local protection device, an implementation scheme for local protection device grid connection and trial operation based on quasi twoterminal prefabrication is proposed. And focus is made on the installation scheme based on secondary system prefabricated box which realizes the local protection interval and prefabricated installation. Based on the structural and functional configuration of the prefabricated box for secondary system, the networking scheme of local protection is put forward, and the prefabricated interface and objectorientation loop connection scheme based on secondary system prefabricated box is emphasized.
    Economic analysis of low temperature flue gas waste heat utilization in distributed energy system
    JIANG Ting1,2,XU Jingjing1,2,MA Qin1,2,YU Li1,2
    2019, 41(5):  46-49. 
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    Taking LM2500+G4 gas turbine combined cycle distributed energy system as a research object, the heat of low temperature flue gas is absorbed by expanded heat exchange surface at the tail of the waste heat boiler. And the waterwater heat exchanger and the hot water storage tank are arranged for hot water storage. There are 9 configuration schemes for domestic hot water supplying system using flue gas waste heat, according to 3 waste heat utilization amounts and 3 kinds of transmission modes.Their economical characteristics are analyzed under certain hot water or tap water price level. The investment recovery period of 9 configuration schemes are all between 1~3 years, which are of good economy. With unchanged water transmission mode, the more waste heat is utilized, the better system economy will be. And with constant waste heat utilization, the shorter water storage time is, the better system economy will be.
    Energysaving retrofit of 2×1000MW unit ash handling system
    ZHAO Xiaoqiang,LI Shaogang,HAN Lina
    2019, 41(5):  50-51. 
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    There is insufficient gasification air volume, high power consumption, high failure rate and high maintenance cost in the pneumatic ash handling system for ESP of 2×1000MW ultrasupercritical coalfired unit in Huadian Laizhou Power Generation Company Limited. Taking advantage of energysaving retrofit, the combination of the ESP dust collector gasification fan and the boiler desulfurization/oxidation fan isproposed. Comparing the gasification air volume, failure rate and energy saving before and after the transformation, it is found out that the unit runs stably, the gasification air volume is increased, the maintenance cost of the equipment is reduced, and the energy saving effect is obvious after the retrofit.
    Exploration on gas flue ultralow emission and desulfurization wastewater zero discharge transformation in coalfired power plants
    TAN Zhiling1,PENG Geliang1,CHEN Quanxi2,HUANG Guoxia3,FU Jiangtao2
    2019, 41(5):  52-55. 
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    In order to ensure the concentration of flu gas at the outlet of a dust precipitator meets the ultralow emission standard, a modification scheme of “1+3” electric bag composite dust collector combining with zero discharge of desulfurization wastewater is proposed, which can simultaneously reduce the emission of flue and wastewater. The transformation results show that the mass concentration of flue at the outlet of the electric bag filter is less than 10mg/m3, and the total concentration of flue discharged from the power plant is less than 5mg/m3. After the desulfurization wastewater is sprayed into the flue, the relative humidity of the flue gas increases, the flue temperature decreases and dust removal efficiency of the bag filter is improved. As the amount of desulfurization wastewater injected  increases, the dust removal efficiency of the bag filter is improved.
    Analysis of fuelsaving efficiency after oil gun reformation of 300MW coalfired unit
    HE Changyu,ZHOU Lin,LI Zhaofeng
    2019, 41(5):  56-58. 
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    In view of the the high pressure, poor atomizing efficiency and high fuel consumption of the original mechanical atomizing oil gun the is poor, 2 mechanical atomizing oil guns for boilers were replaced by bubble atomizing oil gun in 2017. And to original fuel system was reformed. Through contrast and analysis, good economic and environmental benefits are proved to be achieved.
    Application analysis of high efficiency microporous membrane ceramic filtration technology in coalcontained wastewater treatment in power plants
    WANG Renlei,HENG Shiquan,LI Haiyang,YU Jiang
    2019, 41(5):  59-61. 
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    A power plant in southwest China uses high efficiency microporous membrane ceramic filtration technology to treat coalcontained wastewater. The results show that the final suspended solids(SS) can be kept below 10 mg/L, which fully meets the requirement of power plant wastewater reusage. The treatment process is characterized by reliable technology, stable operation, simple operation and small area.It can be used as reference for wastewater treatment in related industries.
    Design and application of dry and water mist dust suppression system for ship unloader on  bulk terminal
    DENG Ruyong
    2019, 41(5):  62-64. 
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    In recent years, with the raising of blending proportion of highdust coal, dust pollution in the coal handling and unloading process at bulk terminals is becoming increasingly severe. But at present, the widely used dust suppression technology is water spray dust suppression system which is of unsatisfactory effect and consumes a large amount of water. By analyzing the specific unloading conditions of the coalfired in docks along rivers, a dry and water mist dust suppression system integrating dry mist and water spray dust suppression system is proposed, its working principle and structural composition are introduced in detail. The practical application shows that the dry and water mist suppression system has a satisfied effect on the unorganized emission control of dust in the bulk terminal.
    Multiloop recording scheme for distribution network terminals based on MK64 platform
    ZHU Chongyang
    2019, 41(5):  65-68. 
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    At present,most of the hardware platforms in distribution network are of low main frequency and small memory, and are mainly used on single loop device in feeder terminal units(FTU).As for the multiloop scenario in data transmission unit (DTU), only the fundamental functions can be implemented.Realizing multiloop sampling and recording requires large data file storage and high realtime application functions,which has high requirements for the main frequency and memory.Aiming at this situation,a method based on Freescale MK64 platform and external SDRAM is designed.It can be used in DTU multiloop recording storage scheme to support fast trigger recording and correct file storage under 4 fault sequences.Feasibility of the scheme has been verified by sampling data and waveform files of the actual device.
    Fault diagnosis and analysis of gear breaking of low speed balltube mill speed reducer
    WU Changhao,CAO Jingfang
    2019, 41(5):  69-72. 
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    There was abnormal sound in the balltube mill speed reducer and motor of a 635MW unit. Applying vibration diagnosis and analysis technology,the reason for the abnormal sound is found out to be broken teeth in lowspeed gear of reducer. The severity of the failure is judged accurately and targeted treatment is made timely, which avoids further expansion of equipment failure.
    Treatment and preventive measures for an unloading steam turbine during the RB of an S109FA gassteam combined cycle unit
    WAN Zhiyong
    2019, 41(5):  73-75. 
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    In the operation of an S109FA gassteam combined cycle unit, there was an RB due to the failure of the blow off valve. During the loadreduction process, steam turbine did not unload while the gas turbine unloaded. In order to avoid metal thermal stress overrun of the steam turbine caused by the sudden temperature drop of main and reheat steam after the unloading of gas turbine, treatment principle and preventive measures to address the abnormality of the unit are proposed.
    Causes and treatment of overlimit bearing vibration of GE PG9171E heavyduty gas turbine
    ZHOU Xinghong
    2019, 41(5):  76-77. 
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    Introduces an overlimit bearing vibration of GE PG9171E heavyduty gas turbine after overhaul. It analyzes the possible causes for the bearing vibration, formulate the troubleshooting processing, summarizes the experience and provide reference in dealing with overlimit bearingvibration.
    Analysis and treatment for fast scaling in 300MW subcritical steam turbine
    XIAN Jianwei,DAI Shujian
    2019, 41(5):  78-.80. 
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    Accumulated water of a 300MW steam turbine was sucked into condensate system by maloperation of the electric drain valve of the hot well, which deteriorated the steam quality, caused serious scaling in the flow passage of the steam turbine and affected the output of the unit. By means of desalinated water cleaning and sand blasting treatment, the salt scale of steam turbine can be effectively removed .The safe, economic and stable operation of the unit can be ensured.