Power Equipment

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  • 2017 Volume 31 Issue 1
    Published: 15 January 2017
      
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  • Effects of Impinging Distance on Simultaneous Desulfurization and Denitrification in an Impinging Stream Absorber
    Song Jie, Wu Bo, Su Yinhai, Zhang Jichao, Qian Dawei, Xiong Yuanquan
    2017, 31(1): 1-8.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the effects of nozzle spacing on the flow field in an impinging stream absorber and on the simultaneous removal of SO2 and NOx by wet process using aqueous solution of urea, a 3D numerical model was built based on Euler-Euler gas-liquid model coupled with kinetic theory of granular flow to simulate the process of simultaneous SO2 and NOx removal. Results show that with the rise of dimensionless nozzle spacing (S/D), the desulfurization and denitrification efficiency are kept at 94% and 40%~50%, respectively. Highest denitrification efficiency occurs in the case of S/D=2.4~3.1.
  • Inferential Predictive Control of a Medium-speed Coal Mill
    Jiao Jian, Li Yiguo, Shen Jiong
    2017, 31(1): 9-13.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A mechanism model was established for the pulverizing system of a medium-speed coal mill, of which the parameters were identified with field data by prediction error method, so as to obtain a more accurate model. According to the mechanism model, the moving horizon estimation method was used to estimate the outlet flow of the coal mill, and subsequently the estimated results were compared with model outputs. Based on analysis of the disadvantages existing in the control system of present medium-speed coal mills, an inferential predictive controller was designed by taking the mill outputs as the controlled variables. Simulation results show that the new control method can shorten the delay time of the coal pulverizing system and speed up the response of the unit to AGC command.
  • Experimental Study of Ash Fouling Status on Convective Heating Surfaces of Large Thermal Power Boilers
    Zhang Yangyang, Pan Xuan
    2017, 31(1): 14-17.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on the off-line data and additional data of working fluids and flue gas collected by DCS of a power plant, heat loss and thermal efficiency of main convective heating surfaces were calculated on the basis of energy and mass balance principle for the whole and partial boiler. A calculation model was derived for the fouling rate of boiler considering the influence of tube wall heat accumulation on the thermal balance and fouling rate calculation under variable load conditions. A combined dynamic-static model of ash fouling monitoring was established based on already existing static model and considering the influence of load variation on the fouling rate calculation. Relevant software for ash fouling measurement and detection was developed and applied to guide soot blowing in a 600 MW thermal power boiler in Tashan Power Plant.
  • Simulation of a Small-scale Double Tank Thermal Storage System Based on ANSYS
    Li Yanan, Du Zhongling, Chen Jiufa
    2017, 31(1): 18-22,29.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To promote the application of thermal storage system in small-scale solar thermal power stations, a dual tank thermal storage system was designed and modeled, which was subsequently analyzed using ANSYS software. Results show that the temperature of both the molten salt tank and the main body varies stably with time, while that of the edge and bottom drops greatly. Side wall insulation layer has greater contribution to the effect of thermal insulation than the top layer. The heat loss increases with the rise of storage temperature, with gradually reducing growth rate. The height-to-diameter ratio has little effect on the heat loss.
  • Mechanism of NOx Emission Reduction by Air-staged Combustion and the Influencing Factors
    Shao Weitao, Wang Wenhuan, Pan Weiguo
    2017, 31(1): 23-25.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the mechanism of NOx emission reduction by air-staged combustion in coal-fired boilers, together with an analysis on the factors influencing the efficiency of air-staged combustion, and a discussion on the variation law of NOx generation with various factors. Results show that the NOx generation increases with the rise of temperature and excess air in the furnace, which reduces with the rise of flue gas residence time in the furnace and the fineness of pulverized coal particles.
  • Design of Nuclear Power Plant D-RAP Database
    Wu Jie, Liu Haibin, Hu Juntao, Hua Yuchao
    2017, 31(1): 26-29.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By analyzing the procedure and main steps of design reliability assurance program (D-RAP), a D-RAP database has been designed to manage the documents, data and information formed during the implementation of D-RAP. The database can assist analysts to quantitatively evaluate the operating experience (OPEX) report and record the documents and data obtained during evaluation. Taking account of the software interface for probabilistic safety assessment (PSA), the database is able to provide data inputs for PSA analysis and risk monitoring in power plant operation. The documents, data and information related to D-RAP equipment can be inquired conveniently and packaged as O-RAP inputs, which are linked with each other in the database.
  • Analysis and Treatment on Packing Leakage of a Steam Trap Valve
    Qin Bojie, Han Guanghui, Li Yong, Gu Liqiang
    2017, 31(1): 30-32.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the leakage problems existing in a steam trap valve on conventional island of a certain nuclear power plant due to frequent actions of the valve, high-frequency reciprocating tests were conducted based on the principle of packing sealing, and subsequently different properties of the graphite seal ring with different incisions and densities were obtained by simulating the actions of the valve, after which a new type of packing was developed. The frequency of packing leakage has been significantly decreased after the new packing is applied for one and half years.
  • Seismic Analysis on 1E Class Power Generator for Auxiliary Feed Pump
    You Guoying, Zhang Zhilu, Liu Yinfang, Li Yi
    2017, 31(1): 33-36,39.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Finite element method was adopted to analyze the seismic performance of a 1E class power generator for the diesel engine-driven auxiliary feed pump in a certain nuclear power plant, so as to verify that the power generator can withstand SSE load and maintain its structural and functional integrities. A mechanical model was built for the generator based on pre- and post-treatment software PATRAN, while static mechanical analysis, modal analysis as well as seismic response analysis of the structure were then carried out via finite element analysis software NASTRAN. According to the design specifications, structural stress and displacement were evaluated under various load combinations, such as the gravity, operating load, earthquake load and so on. Results show that the structural design of the power generator satisfies the requirements of relevant standards.
  • Analysis and Treatment of Quality Issues Occurring in Manufacture of AP1000 Condenser Water Chambers
    Sun Xiaoshi, Wang Yuxi
    2017, 31(1): 37-39.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the quality problems occurring in manufacture of the AP1000 condenser chamber in Sanmen Nuclear Power Plant, such as the deformation formed in assembly and welding, the deformation and cracking formed during water pressure testing due to overpressure reasons, etc., an analysis was conducted based on relevant manufacturing drawings and technical documents of the condenser water chamber, after which corresponding countermeasures were proposed and taken. Results show that the manufacturing problems can be effectively solved by taking above countermeasures.
  • Cause Analysis and Treatment on the Shaking of Drum Screen Drive Gear Unit in Nuclear Power Plant
    Zhang Yu
    2017, 31(1): 40-42.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the integral shaking of drum screen drive gear unit in a nuclear power plant, the meshing clearance of related driving mechanism was adjusted, and subsequently the shaking phenomenon was eliminated. To prevent such shaking from happening again, a force analysis was carried out on the gear meshing, based on which, the primary cause was found, while some suggestions were proposed for future quality management and control during equipment manufacturing and installation.
  • Analysis on the Setting of Condenser Malfunction Setpoint in Nuclear Power Station
    Huang Meihua, Su Hong
    2017, 31(1): 43-47.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    During the commissioning of a certain nuclear power station, the condenser malfunction is activated due to unreasonable setting of the condenser pressure setpoint. The causes were fully analyzed from the aspects of nuclear/conventional island design as well as relevant I&C specialties. Based on the heat-transfer principle and required software, detailed calculation and risk judgment were carried out, and subsequently an optimal design scheme was proposed, which can effectively improve the operation safety and economic performance of relevant nuclear power reactors and steam turbines.
  • Full-process Regulation Practice Using Steam Feed Pump Instead of Electric Feed Pump in Jinwan Power Plant
    Hou Jianxiong
    2017, 31(1): 48-51,54.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the full-process regulation practice using steam pump instead of electric pump in the supercritical unit of Jinwan Power Plant. In view of the disadvantages of frequent mediation and high power consumption of electric feed pump, the way to use steam feed pump instead of electric feed pump during unit starting was proposed. After application of the method previously proposed, the outsourcing electricity is significantly reduced during start-up and shut-down of the unit, while the start-up speed is accelerated, the feed pump combining operation is simplified, the maintenance cost of electric feed pump is reduced, with good economic benefits obtained, which may serve as a reference for full-process regulation using steam feed pump instead of electric feed pump in supercritical units.
  • Vibration Diagnosis and Treatment for the Feed Pump Turbine of a 660 MW Unit
    Chen Chen, Fang Yuxiang, Fu Xingjun, Xing Haibo
    2017, 31(1): 52-54.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Sudden abnormal vibrations have occurred for many times in auxiliary engine B of the No.2 600 MW ultra-supercritical unit in a power plant since its operation for a period of time. Through variable oil temperature test, diagnostic analysis and vibration measurement of the feed pump turbine, a vibration treatment scheme is provided and implemented during overhaul, after which the vibration faults are finally eliminated, while the reliability of the feed pump turbine is improved.
  • Effects of Operation Mode on the Pulverizing Characteristics of an MPS225HP-II Coal Mill
    Wang Chuanjun, Wang Jianwei
    2017, 31(1): 55-57.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the MPS225HP-II coal mill in a 600 MW unit as an example, the pulverized coal was isokinetically sampled from the pipeline by adjusting the operating parameters of relevant equipment, so as to analyze the influence of following factors on the pulverizing characteristics, such as the loading force of roller, the opening degree of baffle and the feed rate of coal, etc. Results show that the pulverized coal would become finer when the loading force rises; however, it would become coarser when the loading force gets over large. With the rise of baffle opening, the pulverized coal gets coarser, which would get coarser by 2%~3% with the rise of coal feed rate.
  • Causes and Prevention of Gas Turbine Honeycomb Seal Wear
    Liu Jiansheng
    2017, 31(1): 58-60.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the unrecoverable thermal efficiency loss of gas turbines caused by the gap enlargement in flow passage due to seal wear, a study was made to the design and start-up conditions of the gas turbine, after which the seal wear was found to be caused by unmatched expansion between the stator and rotor parts. Corresponding countermeasures were proposed to reduce the seal wear, which may serve as a reference for operation, maintenance and management of gas turbine power generation equipment.
  • Retrofit and Optimization of a Power Plant Boiler Air Heater
    Wu Yanbin, Yang Liancheng
    2017, 31(1): 61-63.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problems existing in the air heater of a 1 000 MW boiler unit, such as serious ash deposition on the heat sink, high power consumption of the forced draft fan, and frequent occurrence of tube bank leakage, etc., a retrofit was conducted during overhaul period using the air heater of rotary energy-saving type instead of the old one, so as to ensure stable operation of relevant boiler equipment. By comparing the operation parameters before and after retrofit, it can be seen that the inlet temperature of the air heater is significantly improved, with obvious energy saving effect obtained, thus achieving stable operation of the denitrification system.
  • Reduction of LP Cylinder Exhaust Temperature Using the Condensate of Steam Pump
    Zhang Xiaobo
    2017, 31(1): 64-66.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    After the retrofit on the reduction of LP cylinder exhaust temperature using the condensate of steam pump, data collection and analysis were carried out for relevant equipment. Results show that the exhaust temperature is effectively reduced after retrofit, while the operation safety of unit is improved, with high economic benefits obtained.
  • Analysis and Improvement on Low Vacuum Problem of a Steam Turbine Driving an Induced Draft Fan
    Wang Tao
    2017, 31(1): 67-70.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of low vacuum operation of a steam turbine driving an induced draft fan for a 350 MW supercritical turbo-generator unit, an analysis was conducted, based on which improvement measures were put forward from the aspects of circulation water flow and temperature, air leakage of vacuum system and adjustment of steam turbine operating parameters, etc. Results show that after taking corresponding countermeasures, the operation vacuum of the steam turbine to drive an induced draft fan can satisfy the design requirements of the manufacturer, thus providing important guarantee for safe, economic and efficient operation of the unit.