Power Equipment

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  • 2016 Volume 30 Issue 6
    Published: 15 November 2016
      
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  • Experimental Measurement and Numerical Calculation of Supersaturated Water Vapor Environment
    Meng Qiang, Zhang Jun, Yu Yan, Xu Junchao, Zhong Hui
    2016, 30(6): 363-367.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The highly humid gas from wet flue gas desulfurization (WFGD) system was cooled to build the supersaturated vapor environment in condensation chamber. An experimental setup was designed for indirect measurement of the supersaturation and a model was established for calculation of heat and mass transfer in the condensation chamber, so as to theoretically and experimentally analyze the effects of cooling water temperature on the supersaturation. Both results show that cooling the highly humid gas of WFGD system can effectively build the supersaturated environment, and with the decrease of tube wall temperature, the supersaturation in condensation chamber increases obviously. Calculation results indicate that the highest supersaturation appears in the area near chamber wall under the condition of same wall temperature. The supersaturation first increases and then decreases along axial direction of the chamber.
  • Study on Factors Influencing the Temperature Field of a Tangentially-fired Boiler Based on Numerical Simulation
    Yang Kang, Liu Xichui, Shen Jiong
    2016, 30(6): 368-373.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To explore the influence of different factors on the temperature field in tangentially-fired boilers, the CFD software was applied to simulate the temperature field of a 220 t/h tangentially-fired boiler respectively at different boiler loads, excess air ratios, secondary air distribution, pulverized coal distribution and different qualities of coal (calorific value), etc. Results show that the average temperature of each section has a high linearly correlation to the boiler load, excess air ratio and calorific value of coal. The variation of load has the most balanced impacts on the temperature field of each layer, while that of pulverized coal distribution has the least impacts.
  • Optimization on Primary Frequency Regulation of Large Power Units
    Tang Keyi, Yang Jianming, Cai Xidong
    2016, 30(6): 374-377.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problem that large power units have poor primary frequency regulation performance due to limited energy storage in the concurrent boiler, an optimization method was proposed for primary frequency regulation by adjusting the amount of extracted steam to high-pressure heaters when severe grid frequency deviation happens. Mutual effects of both the turbine and the regenerative system were achieved by modifying common simulation models of large power units, based on which the optimization method was verified. Results show that the proposed method can remarkably widen the range and improve the performance of frequency regulation.
  • Study on Pulverized Coal Properties and Gradation Optimization of a MGS4060A Double-in Double-out Tubular Coal Mill
    Yan Jiaxing, He Xiang, Ma Dafu
    2016, 30(6): 378-381.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Taking the MGS4060A double-in and double-out tubular coal mill in a 600 MW unit as an example, the influence of following factors on the pulverized coal properties was studied by adjusting the operating parameters of mill with different coal powder samples, such as the opening degree of air damper, rotation speed of dynamic separator, outlet temperature of the separator and the coal feed rate, etc. Results show that the pulverized coal becomes finer with increasing rotation speed of dynamic separator, which becomes coarser first and then finer with the rise of coal feed rate, whereas the influence of other factors is not obvious. The pulverized coal properties can be improved by familiarizing with the ball abrasion rules and changing the ball gradation, so as to raise the uniformity index of pulverized coal.
  • Optimization of Sliding Pressure Operation Test for 350 MW Supercritical Steam Turbines
    Huang Xinchang, Xu Xing, Tan Rui
    2016, 30(6): 382-385.
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    Based on analysis of the sliding pressure operation theory of steam turbines, an initial valve position of sliding pressure operation was found by throttling tests on the regulating valve, and then variable load operation tests were conducted at different valve positions near the initial point to verify its correctness. This method is applicable to actual engineering projects, which could help to reduce the number of test points and improve the efficiency of sliding pressure tests.
  • Research on Heat Transfer and Dust Removal Performance of Non-metallic Flue Gas Purification Heat Exchangers
    Xu Xianggen
    2016, 30(6): 386-388.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problems existing in power plants, such as excess emission of flue dust, waste of residual heat in flue gas and corrosion of metallic heat exchanger in flue duct, etc., an experimental system and a non-metallic (PTFE) flue gas purification heat exchanger were developed, which were put into the flue duct behind the desulphurization tower to perform relevant tests. Calculation results based on measured temperatures and pressures before and after the heat exchanger show that its condensation heat transfer coefficient can get up to 170~190 W/(m2·K), proving the non-metallic flue gas purification heat exchanger to have high heat transfer and dust removal performance, which may be spread in the field of flue gas waste heat utilization and dust removal.
  • Modeling of a Doubly-fed Induction Generator and Analysis of its Low-voltage Ride-through Capability
    Guo He, Wang Junyan
    2016, 30(6): 389-394.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An equivalent model was built for doubly-fed induction generators (DFIGs), which were classified into small clusters using K-means clustering algorithm according to specific control scenarios of the propeller pitch angle. In addition, the particle swarm optimization (POS) method was used to realize the identification of optimal parameters, thus establishing a dynamic model of DFIG in case of grid fault and analyzing the important effect of Crowbar circuit in realizing low-voltage ride through (LVRT). The Crowbar circuit was proved to be effective in smoothing the power output of DFIG during fault period and after fault elimination.
  • Analysis on Details Easily Neglected in Design of Piping Supports and Hangers in Power Plant
    Tang Lu, Song Guohui, Li Changning, Wang Guannan, Wang Xuefeng
    2016, 30(6): 395-398.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    As for following three typical details easily neglected in the design of constant supports and hangers, such as choosing supports and hangers without considering their weight, designing supports and hangers without adequately considering their actual sizes, and choosing the snubber without fully considering the travel margin, etc., an analysis was conducted, which may serve as a reference for the design and retrofit of piping supports and hangers.
  • Type Selection of Steam Turbines to Be Operated Under Long-term Low-frequency Conditions
    Tang Lei, Zhang Saimin, Zhang Zhijun, Wang Xiaoyan
    2016, 30(6): 399-402.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    For a certain overseas power plant to be expanded to the capacity of 100 MW class and operated under long-term low-frequency conditions due to the weak local power grid, an analysis was carried to the steam turbine for stable operation under above conditions. The 135 MW reaction steam turbine with untuned blade was then proposed for the retrofit of unit considering the technical and structural features of domestic steam turbines. Results show that for steam turbines to be operated under long-term low-frequency conditions, the scheme proposed has certain advantages in the aspect of unit thermal efficiency, floor area and construction cost, etc., which may serve as a reference for similar projects.
  • Analysis Method for NPP Steam Turbine Characteristics Based on Improved RELAP5 Model
    Yan Siwei, Yang Jianming
    2016, 30(6): 403-406.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To solve the problems existing in RELAP5 steam turbine model, a method is presented to modify the RELAP5 model based on stage group formula, and to correct the calculating formulas in the turbine subprogram module, thus achieving updating of the turbine model. Taking the stage group of a nuclear power unit as a prototype, a single-stage group modeling of steam turbine was completed using the updated RELAP5 model, and subsequently the transient and steady state calculation results were compared with the design parameters. Results show that the modified turbine model with higher accuracy can meet the requirements of the unit on dynamic response.
  • Configuration Optimization and Application Effect of the Condenser Vacuum Pump in a Nuclear Power Station
    Bao Xudong
    2016, 30(6): 407-411.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    An introduction is presented to the equipment selection, configuration optimization and application effect of the condenser vacuum pump in a 1 089 MW nuclear power station, including an analysis on the necessity of adding air ejector to the water-ring vacuum pump and on the factors influencing the configuration optimization of the condenser vacuum pump. Meanwhile, design requirements and configuration schemes of 3×100%, 3×50% and 3×75% capacity were proposed for the condenser vacuum pump. Analysis and application results show that the scheme of 3×75% capacity is relatively reasonable and economical.
  • Research on Data Processing Method in Reliability Experiment of Squib Valve
    Wu Jie, He Jie, Bao Tangtang
    2016, 30(6): 412-416.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The data of reliability experiment for three parts (igniter, cartridge case and mechanical component) of squib valve were respectively converted into Beta distribution, so as to work out the reliability prior distribution by Monte Carlo simulation, and then to obtain the posterior distribution by Bayesian updating method within quality factors of prior and sample data.
  • Overhaul and Inspection of a M701F Gas Turbine
    Bai Long, Sun Qiang
    2016, 30(6): 417-420.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Process analysis was conducted to the first overhaul of a M701F gas turbine, including the main procedure and construction items. Corresponding countermeasures were proposed for problems found in the overhaul, such as radial clearance out of tolerance, damage of compressor stator blade and cracking of exhaust diffuser, etc. Results show that the overhaul process analysis is reasonable and the treatment measures are effective, which may serve as a reference for overhaul of similar projects.
  • Engineering Practice of a 1 000 MW Double-reheat Ultra-supercritical Boiler
    Jiang Deyong, Huang Jun
    2016, 30(6): 421-424.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Technical features of a self-developed double-reheat boiler designed and manufactured by a domestic boiler works were introduced, while main parameters for boiler commissioning and unit operation as well as actual conditions of environmental protection were analyzed by solving problems existing in the boiler installation, which proves the boiler design scheme to be correct and may serve as a reference for construction of similar double-reheat boilers.
  • Risk Analysis and Countermeasures for High-pressure Main Stop Valve in a 600 MW Unit During Full Stroke Test
    Li Xingmin
    2016, 30(6): 425-428.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the security risk of a steam turbine high-pressure main stop valve during full stroke test, and ensure the safe and stable operation of the unit, an analysis was conducted to the test process and common risks, so as to find out specific ideas and methods to further improve the test logic and strengthen the equipment maintenance. Practice shows that attention should be paid to the changes of monitor light plate, DCS display and other light signals, and the test should be ended immediately in case of any abnormal signals observed, when corresponding countermeasures should be taken to reduce the security risk occurring in full stroke test of the high-pressure main stop valve.
  • Problem Analysis and Optimization of a 600 MW Steam Turbine Control System During Commissioning
    Yu Jun, Gong Zhuomin
    2016, 30(6): 429-431.
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    An introduction was presented to the control principle of digital electrohydraulic (DEH) control system for a D600S steam turbine, with focus on analysis of the problems occurring in commissioning of the control system, based on which corresponding countermeasures were proposed. It has been found that the faults were basically caused by manual misoperation. The DEH system was then able to work safely and stably after above countermeasures had been taken.
  • Cause Analysis of V/Hz Limiter Action for GE EX2100 Excitation Regulators
    Jiang Zhihui, Shi Yang, Liu Chunmei
    2016, 30(6): 432-434.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Based on detailed analysis of the operating principle of V/Hz limiter for GE EX2100 excitation regulator, the reason of frequently misstated excitation restriction occurring in the generator excitation system of a domestic power plant was found to be caused by design deficiency in the GE EX2100 excitation regulator, for which corresponding improvement measures were suggested.
  • Retrofit of a Boiler Dust Precipitator
    Liang Jianmin
    2016, 30(6): 435-437.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    To reduce the pollutants emission from a boiler, the original electrostatic precipitator was changed into bag-type dust collector, which was staggeringly arranged with auxiliary flow-equalizing device equipped to ensure the uniformity of flue gas flow. After retrofit, the emission concentration of dust has been reduced from 99.47 mg/m3 to 5.93 mg/m3, with the dust collecting rate up to 99.94%, achieving the intended purpose.