Power Equipment

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  • 2015 Volume 29 Issue 3
    Published: 15 May 2015
      
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  • Analysis on Offdesign Performanceof a TwoPullOne GTCC Unit Based on SVM
    Zhu Yadi, Wei Hongqi, Wang Lili, Sheng Bo
    2015, 29(3): 155.
    Abstract ( )   Knowledge map   Save
    construction of the equipment, the environmental conditions and the operation mode, etc., which have the characteristics of strongcoupling, large delay and great uncertainties. Using support vector machine (SVM) and the genetic algorithm (GA), a model was established to analyze the relationship between above elements and the heat consumption, and the results were compared with conventional SVM method, so as to verify the reliability and accuracy of the GASVM model, which was subsequently used to analyze the offdesign performance of the GTCC unit under twopullone operation mode; simultaneously, a GASVM model under onepullone operation mode was set up respectively for the two gas turbines to comparatively analyze their offdesign performance, when good results were obtained.
  • Heat Consumption Analysis for the 1 000 MW DoublereheatSteam Turbine with External Steam Coolers
    Xia Xiaohua, Yang Yu, Fan Shiwang, Peng Zeying, Yang Jiandao
    2015, 29(3): 160.
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    External steam coolers are widely used in largecapacity highparameters reheat unit, due to their capability in recovering the superheat degree of regenerative steam and raising the temperature of feed water, thus improving the cycle efficiency. In this paper, an energy consumption analysis was carried out to a 1 000 MW doublereheat turbine with external steam coolers under THA, TMCR, VWO, 75%THA and 50%THA working conditions based on energy level efficiency method, and the results were compared with those of conventional schemes. Results show that the scheme with external steam coolers mainly reduces the heat consumption in auxiliary section, and in a 600 ℃ thermal system with two external coolers, the heat consumption may be reduced by about 27 kJ/(kW〖DK1〗·h).
  • Application of Optimal Regression Method in Coal Blending Process
    Gui Liangming, Mao Xiaofei, Chen linguo, Liu Fasheng
    2015, 29(3): 164.
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    To understand the influences of coal blending ratio on coal consumption characteristics of the unit, and to optimize the coal blending performance, two power units in a power plant were taken as the object of study, and subsequently the effects of load and coal blending ratio on coal consumption of the unit were analyzed using optimal regression method, during which optimal operation conditions and blending ratios were found, resulting in high coal blending performance and low coal consumption. Study results show that this method has great significance in spreading the data processing way of coal blending for power plants.
  • Research on Governing Stage Characteristics of a 300 MW NozzleGoverning Turbine in Sequence Valve Operation Mode
    Sun Youyuan, Xu Jianqun, Jiang Weili
    2015, 29(3): 168.
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    The flow characteristics of governing valve was analyzed through combined method of simulation experiments and thermodynamic calculation, and the relationship between pressure and flow rate of governing stage was obtained in sequence operation mode of the governing valve. The enthalpy drop of governing stage was calculated with actual examples in case that the sequence valve was operated at constant pressure, thus obtaining the calculation model for mixing enthalpy in the steam chamber of governing stage, which may serve as a reference for working condition analysis of the governing stage under varying conditions.
  • Economy Analysis of a 1000 MW Ultra Supercritical Unit with Installation of No.0 Highpressure Heater
    Bao Weiwei
    2015, 29(3): 172.
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    As to the problem that the efficiency of thermal cycle becomes low when thermal power unit works at partial loads, a technology named No0 highpressure heater which can improve the economy of the unit with partial loads is introduced. Based on the working principle of No0 highpressure heater, detail calculation and analysis were conducted to the economy of a 1 000MW highperformance ultra supercritical power unit with installation of No.0 highpressure heater. Results show that after application of this technology, the unit heat consumption has been reduced by 30 kJ/(kW·h）, with obvious economic benefits.
  • Study on Control Strategies of V94.3A Gas Turbine
    Cao Yue, Zhang Weijie, Yang Jingqi
    2015, 29(3): 176.
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    An introduction is being presented to the control system classification of Siemens V94.3A gas turbine, according to which an analysis was carried out to the control logic. The master control system cooperates with the IGV control system to determine the ratio of fuel and air, and the fuel control system can switch the combustion method. Above control systems help to realize control over different operation stages.
  • Comparison of Unit Safety and Economy undertwo Modes of Steam Distribution
    Wang Jinquan, Wang Jianqiang, Shao Feng
    2015, 29(3): 180.
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    Taking a 660 MW pure condensing turbine as an example, by comparing the design curves under two steam distribution modes respectively controlled by sequence valve and composite valve, the throttle loss of governing valve under sequence valve control was found to be relatively small within normal load range; keeping the load unchanged, and switching the control mode from composite valve to sequence valve, the pressure of governing stage would reduce by 0.4 MPa, and the No.1 bearing vibration would drop. Comparing all the safety and economic indicators obtained in load tests under two steam distribution modes, the heat rates at 600 MW were basically the same, but at 450~580 MW, the average heat rate under sequence valve mode was 30 kJ/(kW·h) lower than the composite valve mode, and the No.1 bearing vibration in Y direction was 45 μm smaller. Test results show that compared with composite valve mode, the sequence valve control is better regarding safety and economic efficiency, which may serve as a reference for improvement of steam distribution mode of similar units.
  • Structural Strength Design of a Selfsustaining Biomass Boiler
    Du Weiguang, Song Fengqin, Li Chaohua, Cheng Fengyuan
    2015, 29(3): 184.
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    Focused on the strength design, an introduction is being presented to the YG130/9.8T3 selfsustaining biomass boiler with its drum supported by two downcomers. The strength calculation and assessment method are proposed for the supports of lower water wall header and for the drum at downcomer nozzle area, while the stability calculation method suggested for the downcomer, which may serve as a reference for the design of similar selfsustaining biomass boilers.
  • EPMA Deviation Analysis of Element Distribution in Plasma Surfaced Layer over Gas Turbine Bush
    Zhong Chengshan, Zhao Zhongping, Fan Yingwei
    2015, 29(3): 188.
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    An electron probe microanalysis (EPMA) was performed to the element distribution in plasma surfaced layer over a gas turbine bush by two methods, based on which the rate of dilution was calculated. By comparing the test results of two methods, causes leading to the difference of test data were analyzed, while the influence of data difference on the final results was studied.
  • Water Wall Hydrodynamic Calculation for Low NOx BurnerRetrofit of a 500 MW Supercritical Oncethrough Boiler
    Li Guangrui
    2015, 29(3): 192.
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    By simplifying the water wall flow loop as following three kinds of components: flow circuit, pressure node and connection tube, hydrodynamic calculation was carried out to the water wall after low NOxretrofit of a 500 MW supercritical oncethrough boiler, so as to analyze the distribution of water wall temperature along furnace height respectively at the load of 500 MW, 250 MW and 200 MW. Results indicate that at the load of 500 MW, the inner wall temperature, outer wall temperature, intermediate point temperature and fin temperature of the water wall in upper radiation zone are all within allowable range of the material; whereas at the load of 250 MW, the temperature of intermediate point in lower radiation zone does not exceed 510 ℃, indicating that the water wall is safe; but at the load of 200 MW, the safety of boiler operation is to be affected.
  • Introduction to High Backpressure Heating System of Direct Air cooling Units and the Safety Operation
    Huang Zhikun, Zhang Pan, Zhang Yanhui, Xu Zelin, Yang Shibin
    2015, 29(3): 196.
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    An introduction is being presented to the high backpressure heating system of a direct aircooling unit, together with a description to several key problems that may occur during high backpressure operation conditions. The airblast failure in laststage blade of lowpressure cylinder under high backpressure operation mode could be prevented by controlling the flow rate and inlet temperature of the steam. When the inlet flow rate of one row is low, freezing of the row could be forbidden through opening the condensate valve and closing the vacuum valve of the row. The economy of the heating mode could be improved by optimizing the load allocation. The efficiency of the water ring vacuum pump could be raised by adding cooling equipment for the working medium. Practical applications prove the high backpressure heating mode of direct aircooling unit to be safe and reliable.
  • Cause Analysis of Lowfrequency Vibration in TurboGenerator Sets
    Chen Songping
    2015, 29(3): 200.
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    Lowfrequency vibration is a common vibration fault in large turbogenerator sets, threatening the safe operation of the units. By analyzing the lowfrequency vibration cases of domestic turbogenerator sets in recent years, the reasons, features and variation tendency of lowfrequency vibration faults are summarized, and subsequently corresponding diagnosis criteria and preventative measures are suggested, which may serve as a reference for diagnosis and treatment of similar faults.
  • Singleside Isolation for Internal Maintenance ofan Electrostatic Precipitator in 1 000 MW Boiler
    Dong Wuming, Wang Guohong, Zhang Shuli
    2015, 29(3): 205.
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    To examine and repair the failed electrostatic precipitator in a 1000MW boiler, an available technology was proposed and applied by isolating single side of the precipitator. Dangerous points that had occurred and been treated under high load conditions during trouble shooting process were introduced, while reasonable arrangement of the isolation sequence was presented. Above method was proved to be reliable, which had ensured the constructed conditions and guaranteed the safe and stable operation of the unit.
  • Logic Optimization of a Primary Frequency Modulation System
    Yu Chuangchang
    2015, 29(3): 209.
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    To improve the operation performance of primary frequency modulation system in a 125 MW unit, a method was proposed to respectively set the modified power curves under low and highfrequency deviation conditions. It is concluded that better frequency modulation effect can be obtained only after the boiler combustion control system is appropriately retrofitted.
  • Application of Ovation Control System in 9E Gas Turbines
    Tian Yihua, Li Yongyang, Liu Pengfei, Wang Yigang, Wen Qian
    2015, 29(3): 212.
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    The development and application of Emerson's Ovation control system for 9E gas turbine were presented. An Ovation control system was successfully implemented as an integral part of the lowNOx retrofitting of a 9E gas turbine, involving the design, development, and commissioning of related hardware & software. Testing & commissioning results and operating performances had fully demonstrated the Ovation control system to be satisfactory in every aspect of the control requirements and offered significant convenience in gas turbine operation and maintenance.
  • Judgment of Abnormal TSI Measurements Using Multimeter
    Zhou Yiqin
    2015, 29(3): 216.
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    It is necessary to judge relevant measured values when there is an abnormal display on the turbine supervisory instrumentation (TSI). An introduction is being presented to the calculation way of various TSI measurements, and to how to judge the measurements with multimeter.
  • Problems Concerning Type Selection of Nuclear Steam Turbines
    Ji Runjing
    2015, 29(3): 220.
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    Based on analysis of the technical features of nuclear steam turbine, a detail discussion was made to the antistress corrosion, the rotor structure, the supporting type of LP casing, the antierosion countermeasures and the evaluation of critical speed for the steam turbine, which may serve as a reference for type selection of nuclear steam turbines.
  • Feasibility Analysis on Improving Load Adaptabilityof SCR Denitrification Systems
    Kang Xuezhan
    2015, 29(3): 225.
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    In light of the problem that the SCR denitrification system had to operate in allweather conditions to meet the NOx emission requirement, feasible technical schemes to improve the system′s load adaptability were proposed and compared, with focus on the scheme of staged economizer retrofit and the application, which may serve as a reference for the retrofit of inservice units and the design of newlybuilt units.
  • Discussion on Anaerobic Pyrolysis Technology of Municipal Solid Wastes
    Tao Bangyan, Pan Weiguo, Chen Gefei
    2015, 29(3): 231.
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    To reduce, recycle and reuse the municipal solid wastes (MSWs), an anaerobic pyrolysis technology was developed for the MSW treatment and dumping, which was applied in a 100 t/d demonstration apparatus. Results show that combustible gas, cracked residue, carbon and electric energy were produced in the process, without generation of waste gas, polluted water and secondary pollution, etc.
  • Solution Selection for Ultralow Emission of Air Pollutants Solution Selection for Ultralow Emission of Air Pollutants
    Li Zhongcun, Xu Ganghua, Yang Meicong, Yu Fei
    2015, 29(3): 234.
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    For a1 000 MW ultrasupercritical coalfired unit to be constructed, measures of air pollution treatment was proposed, including the determination of ultralow emission schemes in the aspect of denitrification, dust removal and desulfurization, etc., so as to prevent the unit from needing modification just after being put into operation.