Power Equipment

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  • 2017 Volume 31 Issue 3
    Published: 15 May 2017
      
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  • Comparative Analysis on Power Output and Exergy Efficiency of Mixed and Pure Refrigerant in an ORC System
    Ma Jianchao, Liu Yulan, Chen Jiufa
    2017, 31(3): 145-149.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To compare the power output and exergy efficiency of mixed and pure refrigerant in an ORC system, simulation models were established using Visual Basic software for the system respectively with mixed and pure working fluid, so as to find the performance difference between the R152a/R245fa mixture and each pure refrigerant, obtain the optimum blending ratio, and finally raise the thermodynamic efficiency of the cycle. Results show that the refrigerant mixture with different blending ratios has different effects on the cycle performance, but the effects are generally higher than that of pure refrigerant, which are beneficial to the improvement of cycle efficiency.
  • Visualization Study of Energy Flow in Gas-Steam Combined Cycle Units
    Xu Yinwen, Shi Qiguang, Dong Chenyu, Wang Yao, Sun Haozu
    2017, 31(3): 150-153.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on actual operation data obtained in SIS system of a power plant for F-class gas-steam combined cycle unit, automatic communications were realized through AutoCAD ActiveX and AutoCAD2015 by C#, and simultaneously, an energy flow chart was drawn proportionally for the flow process, thus obtaining the energy flow and loss in various thermodynamic processes, which may serve as a reference for online analysis on energy consumption of in-service gas-steam combined cycle units.
  • Techno-Economic Analysis of a 1 000 MW Ultra Supercritical Unit after System Optimization
    Bao Weiwei
    2017, 31(3): 154-158.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To improve the operation economy of a 1 000 MW ultra supercritical unit, an optimization was conducted on its thermal system by updating relevant design specifications and adding some auxiliary facilities, after which a techno-economic analysis was carried out on the system. Results show that the economy of the thermal system has been improved significantly and the weighted heat consumption of unit has been reduced by 118 kJ/(kW·h), after optimization is carried out with above measures.
  • Test Analysis on Coarse Coal Particles in a ZGM113G Medium-speed Coal Mill
    Li Sha
    2017, 31(3): 159-161.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of coarse coal particles pulverized by a ZGM113G medium-speed coal mill, a series of tests were conducted from the aspects of roller loading force, separator baffle opening, and air-coal ratio, etc. Results show that the problem of coarse coal particles is caused by the worn separator baffle, loosened reverse-flow baffle, too high air-coal ratio and so on. It is suggested that the erosion conditions of internal separator baffles should be inspected periodically, while the inlet primary air flow be calibrated regularly, so as to guarantee a stable operation of the coal mill.
  • Logic Analysis of Coordinated Control System in a 1 000 MW Double Reheat Unit
    Cui Kaifeng, Xu Hailei, Zhang Shiwei, Li Yong
    2017, 31(3): 162-165.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An analysis is conducted on the composition and features of the coordinated control system in a 1 000 MW double reheat unit, including a discussion on the coordinated relations among the boiler air, coal and water subsystem, as well as the coordination between the unit output and power grid demand, together with an introduction to the composition and function of the boiler control, fuel control, feed water control, main steam pressure setting, and so on.
  • Study on the Manufacture of a Long and Thin Variable Stator Blade
    Qiu Xinglin, Zou Bin
    2017, 31(3): 166-170.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Model analysis was conducted on a variable stator blade using deformation theory and stability theory involved in the mechanics of materials, so as to demonstrate the manufacturing feasibility of the blade. Meanwhile, to minimize the deformation and guarantee the precision of airway surface, the machining process and procedures were also studied for the variable stator blade.
  • Study on the Design of Main Components for Small Integral PWRs
    Lin Qian
    2017, 31(3): 171-175.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the design features of main components for new concept integral pressurized water reactors (PWRs), including the design features of integral structures for various types of reactors as well as that of other main components, such as steam generator, reactor coolant pump, control rod driving mechanism and pressurizer, etc. Meanwhile, a comparative analysis is made on technical difference and potential problems of various schemes, which may serve as a reference for research and development of main components for new integral PWRs.
  • Study on Calculation Methodology of Heat Transfer Area for a CPR1000 Steam Generator
    Jiang Chenguang, Deng Debing, Zhao Qingsen, Nie Shenbin
    2017, 31(3): 176-180.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the calculation methodology of heat transfer area of U tubes for vertical natural circulated steam generator, and subsequently calculations of heat transfer area were performed for the 55/19 steam generator designed according to foreign specifications using different calculation methods. Results show that the calculation accuracy of integral method is close to that of partial method, but the difference of calculation results is significant among different models.
  • Analysis and calculation on Load Limit of a Steam Turbine at Varying Outlet Pressures of the Steam Generator
    Si Rui, Huang Meihua
    2017, 31(3): 181-184.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By comprehensively considering the overpower restriction and the security of a steam turbine, an analysis and calculation method was proposed for the setting of its load limit in the case of continuous decline of the steam generator outlet pressure. Based on the operation data of a power plant, simulated calculation was conducted, and the results were proved to be accurate.
  • An Introduction to the Finned Tubes for MSR of Nuclear Power Stations
    Ren Yifeng
    2017, 31(3): 185-187.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the features of finned tube banks for moisture separator reheater (MSR) of nuclear power stations, together with a discussion on problems needing to be cared in manufacture and quality control of the finned tubes, which may serve as a reference for relevant manufacturers of finned tubes.
  • Cause Analysis on Leakage Failure at Tube Bends of Water Wall in an Ultra-supercritical Unit
    Wu Youfu, Hou Zhaotang
    2017, 31(3): 188-192.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    By means of chemical composition analysis, hardness testing, optical microscopy observation, fracture surface analysis, spectrum analysis and finite element numerical simulation, the causes leading to the leakage failure of water wall tubes in a power generation company were investigated. Results show that the failure was mainly caused by both the too large residual stress from cold deformation of water wall during fabricating process and the too large thermal stress generated during operation period, which led to the premature failure of relevant tube bends. Moreover, the corrosive flue gas also accelerated the propagation of related thermal fatigue cracks.
  • Cause Analysis on Compressor Rotating Stall in a Gas Turbine
    Liu Jiansheng
    2017, 31(3): 193-195.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking a 450 MW gas turbine generator set as an example, an introduction is presented to the compressor rotating stall and to the changes of relevant parameters, together with an analysis on the stall mechanism, and subsequently corresponding countermeasures were proposed, which may serve as a reference for treatment of similar faults of gas turbine compressors.
  • Retrofit and Analysis on Deep Air Staging Low NOx Combustion System of a 600 MW Tangentially-fired Boiler
    Yuan Hongwei, Yu Yuexi, Li Fangyong
    2017, 31(3): 196-199.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To study the effect of deep air staging low NOx combustion technology on the pollutant emission, economy and safety of a power plant boiler, based on the deep air staging low NOx combustion retrofit practice for a 600 MW tangentially-fired boiler, the influence of the retrofit on the NOx emission, boiler efficiency, steam temperature and metallic wall temperature was analyzed. Results show that after retrofit, the NOx emission is greatly reduced and the boiler thermal efficiency is increased; however, the boiler steam temperature is increased simultaneously, which leads to the rise of desuperheating water consumption, and to the rise of metallic wall temperature caused by the moving up of heat load, where the tubes of superheater and reheater are easy to be overheated, especially in the load range of 300~600 MW.
  • Treatment on Vibration Fault Occurring in the Shaft System of a 600 MW unit When Crossing Critical Speed
    Cui Yahui, Zhang Junjie, Ge Qing, Hu Jian, Zhang Cong, Gan Zhongming, Zen Weiguang
    2017, 31(3): 200-202.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To deal with the excessive vibration of No.2 and No.3 tile in a subcritical 600 MW unit affecting the startup of unit when crossing the critical speed, the influence coefficient of both ends of the medium-pressure rotor was analyzed after balancing weight was applied, while the structure of bearing ring gasket and pedestal was analyzed. One of the main reasons is considered to be the relatively low equivalent stiffness of the supporting systems for No.2 and No.3 tile. The shaft vibration was able to pass through the critical speed when following three optimization measures were taken, such as optimizing the structure of bearing ring gasket, adding a triangular support to the bearing pedestal, and setting higher requirements for dynamic balancing before delivery, etc., which may serve as a reference for treatment of similar problems occurring in same type of units.
  • RB Test Analysis of a 660 MW Ultra-supercritical Unit after Integration of the Induced Draft Fan with Booster Fan
    Xue Qinghong
    2017, 31(3): 203-208.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the technical scheme, main process and parameters variation of the runback (RB) test after integration of the induced draft fan and booster fan in a 660 MW ultra-supercritical unit, while the test results are analyzed. Results show that the unit has good RB performance after integration retrofit, and the unit load can be quickly reduced to actually achievable values under accident conditions.
  • Parallel Running Control Strategy of Feed Pumps at Low Load of a Supercritical Unit
    Yu Kang, LI Zhuolin
    2017, 31(3): 209-212.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem of feed pump trip occurring at low load of a 600 MW supercritical unit, a method is proposed by opening the high-pressure governing valve of the feed pump turbine in advance through override control when the RB function is not triggered, so as to raise the pump speed to the target value. Results show that the feed water flow of boiler can be prompted rapidly after the control strategy is applied, which helps to secure the safety of unit operation.
  • Optimization and Improvement of a High-pressure Bypass System for Domestic 600 MW Supercritical Units
    Li Yongli, Chen Jun
    2017, 31(3): 213-215.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aiming at the problem that forced shutdown was repeatedly encountered by a domestic 600 MW supercritical unit since its operation due to the leakage fault of high-pressure bypass valve, an analysis was conducted, and subsequently over temperature tube burst was found to be the main reason, which was caused by shrunk flow area or blocked tube resulted from oxide scale falling into the passage of boiler superheaters. The problem has been solved by changing the bypass valve into the detachable type and adding an isolation device in front of the valve.
  • Application of Permanent Magnetism Turbulence Flexible Driving Speed-regulating Technology in Secondary Air Blower of a Boiler
    Yu Fan, Kang Kai
    2017, 31(3): 216-218.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the basic principle and technical features of the permanent magnetism turbulence flexible driving speed-regulating technology, which is adopted to retrofit the speed control device for secondary air blower of a power plant. Results show that after the application of permanent magnetism turbulence flexible driving speed-regulating technology, both the vibration and erosion of the secondary air blower are reduced, thus obtaining significant energy saving effect.
  • Cause Analysis on Tube Burst Accident of an Evaporator and the Preventive Measures
    Zhang Yao, Su Delin, Li Guangyao, Li Kan
    2017, 31(3): 219-222.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An analysis was conducted on the tube burst accident of a waste heat boiler's evaporator, which was found to be caused by thickness reduction of the tube wall due to flow-accelerated corrosion. To prevent such failures from happening again, corrective measures were proposed, such as reducing the start/stop frequency of boiler, control the water quality, adopting the low-alloy steel as evaporator material, enlarging the radius of tube bends, raising the working pressure during boiler design to improve the saturation temperature of evaporator, etc.