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    Boiler Technology
  • Boiler Technology
    Flow Distribution in Vertical Header of Water-cooled Screen for Supercritical CFB Boilers
    ZHANG Dong-qing, YANG Dong, LIU Ji-wu, XIAO Feng
    2013, 33(1): 1-5.
    Abstract ( )   Knowledge map   Save
    Based on the structure of water-cooled screen for a 350 MW supercritical CFB boiler manufactured by Shanghai Boiler Works Co., Ltd., an experimental setup was established to study the air-water two-phase flow in vertical header of the water-cooled screen. Meanwhile a numerical model was set up for the two-phase flow distribution based on mass conservation, momentum conservation and supplementary equations, with which flow distribution in the vertical header was calculated at 35% BMCR and different dryness of steam, so as to obtain the mass flow coefficient of uniformity, maximum mass flow deviation coefficient, gas volume coefficient of uniformity and maximum gas volume deviation coefficient in each branch tube. The calculated results were compared with experimental measurements. Results show that under single operating condition, from branch tube 1 to branch tube 4, the mass flow increases gradually; the mass flow deviation coefficient increasesfrom negative to positive; the gas volume flow reduces gradually; the gas volume coefficient of uniformity decreases from positive to negative. The variation tendency of calculated data agrees well with experimental measurements, and with the rise of steam dryness, the error reduces between the calculated results and actual measurements.
  • Boiler Technology
    Numerical Simulation on Pressure and Flow Distribution in Superheater with T-junction Headers
    ZHOU Yun-long, LIU Xiu
    2013, 33(1): 6-10.
    Abstract ( )   Knowledge map   Save
    To analyze the influence of T-junction structure on flow distribution in superheater with tee-junction(T-junction) headers and subsequently solve the problems of tube burst failure occurring to the superheater, numerical simulations were conducted to a superheater model using Fluent software to study the static pressure distribution and velocity distribution in the superheater, the flow distribution in each branch tube, as well as the fluid velocity and static pressure at each branch inlet. Results show that the fluid near to the tee-structure is low in pressure and high in velocity, while that far away from the region is high in pressure and low in velocity; small vortex only forms in eddy region near T-junction while no vortex in other regions at branch inlet; within the header, the flow in branch tube below the eddy region is relatively low, but that facing the header entrance is the highest; by changing the inlet of the 7th and the 11th tube panel into round shape, the branch flow may be increased significantly.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Creep Strength Analysis on HP Outer Casing of a 1 000 MW Ultra Supercritical Steam Turbine
    JIANG Pu-ning
    2013, 33(1): 11-16.
    Abstract ( )   Knowledge map   Save
    Taking the high-pressure outer casing of a 1 000 MW ultra supercritical steam turbine as an object of study, and by adopting the Norton-Bailey material creep constitutive equation and Cocks-Ashby multiaxial coefficient, the temperature field, stress field and the CA equivalent creep strain dictribution of the 2D axisymmetric model were calculated, during which the unreasonable structure of original design was found out and impoved with corresponding schemes. Results show that the improved structure of the HP outer casing is reasonable; all the calculated results of CA equivalent creep strain are less than those in the recommended criteria for assessment. The high-temperature creep strain of above mentioned outer casing can meet the design requirements.
  • Steam Turbine and Gas Turbine
    High Cycle Fatigue Safety Analysis for Steam Turbine Rotors with Initial Cracks and Its Application to a Welded Rotor
    SHI Jin-yuan, DENG Zhi-cheng, WANG Yong, YANG Yu, LIU Yan, LIU Xia, WANG Zheng-yan, YANG Yan-lei
    2013, 33(1): 17-24.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to the design method of high cycle fatigue life of steam turbine rotors, together with descriptions to analytical methods for high cycle fatigue safety of turbine rotors with initial cracks, and to calculation methods for the mean stress σm, stress amplitude σA and the range ΔKI of stress intensity factors as well as to an experience formula for the fatigue crack growth threshold ΔKR<sub>th of the rotor material. Meanwhile, an analysis method and the assessment criteria for high cycle fatigue safety of steam turbine rotors with initial cracks are given, with an application example listed for high cycle fatigue safety analysis of a welded low-pressure rotor for a half-speed steam turbine in a 1 000 MW nuclear power station. Results show that the analytical methods may be used for safety evaluation and structural optimization of steam turbine rotors, so as to guarantee safety operation of relevant power plants.
    • Engineering Thermophysics
  • Engineering Thermophysics
    Influence of Sudden Expansion Chamber Length on Jet Flow Field in the Chamber with Triangular Inlet
    YUN Ying, CHEN Dong-lin, MI Jian-chun, DENG Tao, CHENG Shan
    2013, 33(1): 25-30.
    Abstract ( )   Knowledge map   Save
    The jet flow field following a sudden expansion chamber with triangular inlet was measured by particle image velocimetry(PIV) technology at different chamber lengths, during which the influence of chamber length on the jet flow characteristics was analyzed. Results show that when the ratio of chamber length to diameter L/D≤1.06, the jet doesn’t oscillate; if L/D=1.36, the jet deflects; if L/D=1.67, the jet oscillates by itself, and the state will be kept in the range of 1.67≤L/D≤2.42.
  • Engineering Thermophysics
    Treatment of Corners in Characteristic Non-Reflecting Boundary Conditions by Direct Numerical Simulation
    LI De-bo, YANG Jian-shan, FAN Jian-ren, LUO Kun, CEN Ke-fa
    2013, 33(1): 31-36.
    Abstract ( )   Knowledge map   Save
    Based on analysis of the coupling treatment method for corners in characteristic non-reflecting boundary conditions, a new mathematical method for corner coupling treatment is put forward. Numerical simulation has been conducted on a spatially evolving compressible round jet and the simulation results are compared with experimental data. Results show that the new mathematical method for corner coupling treatment is effective in the aspect of acoustic reflection treatment and the simulation results properly fit the experimental data.
    • Auxiliary Equipment Technology
  • Auxiliary Equipment Technology
    A Simplified Method for Heat Balance Calculation of Tri-sectional Regenerative Air Heater
    LI Yang, ZHOU Yuan-xiang, XIE Tian, JIANG Hao, HUANG Jia-si,CHANG Dong-feng, WANG Hao, LI Xin
    2013, 33(1): 37-41.
    Abstract ( )   Knowledge map   Save
    A simplified method for heat balance calculation of tri-sectional regenerative air heater is proposed based on actual running parameters and standard calculation code. Taking the scheme of heat transfer area increase for economizer of a 350 MW supercritical power unit as an example, the method was used to calculate the outlet air and gas temperature of the air heater. Results show that the method is applicable without knowing the plate, structural and material parameters of the heater, which are generally difficult to determine, especially in the case when ash blocking or fouling is encountered by the heater, so the prediction accurancy can be greatly increased.Calculated results of exhaust gas temperature, hot primary and secondary air temperature by this method agree well with those by the method of Harbin Boiler Co., Ltd., and the relative error is less than 1% between the two methods.
  • Auxiliary Equipment Technology
    Cold-state Numerical Study on Performance of Rotary TypePulverized Coal Classifier with Bowed-Twisted Blades
    YAN Shun-lin, WEI Jie-ru, DONG Biao, YANG Yu-huan
    2013, 33(1): 42-46.
    Abstract ( )   Knowledge map   Save
    Based on structural features of rotary classifier with straight blades for MPS89k medium speed pulverizer, a new rotary coal classifier with variable cross section and bowed-twisted rotor blades was proposed, to which numerical simulation was performed using Fluent software so as to analyze its comprehensive performance under different conditions of blade structures, and obtain optimum structural parameters of the rotor blade. Results show that for the new coal classier, the optimal twist angle of its rotor blade is 25°, in which case the flow field following the rotor blade is evenly distributed, the air return at both ends of the stator blade is reduced, the erosive wear at bottom of the stator blade is alleviated, and therefore the survice life of the classifier will be elongated. Under the optimmum conditions of rotor blade structure, the outlet fineness of pulverized coal is 1.39%, the comprehensive separation efficiency is 95.83%, the air resistance in solid-gas two-phase flow of the classifier is 1 174 Pa, which can satisfy the requirements of actual engineering projects.
  • Auxiliary Equipment Technology
    Numerical Study on Natural Draft Wet Cooling Tower Fixed with Tilted Windbreak Walls
    ZHOU Lan-xin, MA Shao-shuai, GONG Xue-min, LIU Zheng-liang
    2013, 33(1): 47-52.
    Abstract ( )   Knowledge map   Save
    Based on relevant theories of wet cooling tower, a 3D heat and mass transfer model was established for the natural draft cooling tower of a 1 000 MW power unit using Fluent software, with which the flow and thermal characteristics of circulating cooling water were analyzed on the basis of discrete phase model, while the air/water flow field and air-water heat transfer in the tower simulated. Results show that by installing tilted windbreak walls in the rain zone, a part of outer air may directly enter into the center area to exchange heat with cooling water there, and thus the heat-transfer efficiency is raised. Minimum outlet water temperature may be obtained when the angle is 30 between titled windbreak wall and the vertical plane, in the case that baffle plates are fixed, under which condition the outlet water temperature will be 0.96 K lower than the case that cross windbreak wall is mounted.
  • Auxiliary Equipment Technology
    Dynamic Characteristic Analysis on Impeller of Centrifugal Fan Based on Fluid-Solid Coupling
    WU Zheng-ren, WANG Song-ling, RONG Rui, SUN Zhe
    2013, 33(1): 53-60.
    Abstract ( )   Knowledge map   Save
    Fluid-solid coupling simulation was carried out on the impeller of centrifugal fan using CFX and Ansys software, so as to calculate and analyze the impeller’s strength, modal and vibration characteristics. Results show that after considering the fluid-solid interaction, the aerodynamic performance of the fan hardly changes; however, the maximum total deformation of the impeller is reduced by 2.5% and the maximum equivalent stress is increased by 3.6%; after taking account of the prestressing effect, the natural frequency of the impeller is increased in different degrees according to the order conditions; under stable operation conditions, the main frequency of air pressure fluctuation around the impeller is the same as the blade passing frequency, and the natural frequency of the impeller partially lies in the local resonance region, where the equivalent stress is far less than the fatigue limit of the impeller material, therefore impeller fatigue failure will not be resulted.
    • Energy System Engineering
  • Energy System Engineering
    Integration Study and Performance Index Calculation on Parallel Type IGCC-Methanol Poly-generation Systems
    ZHU Zhi-jie, GU Hua-nian, FAN Xue-fei, CHEN Jian, LIU Chuan-liang
    2013, 33(1): 61-65.
    Abstract ( )   Knowledge map   Save
    Through discussion on parallel type IGCC-methanol poly-generation systems with different types of gas turbines, an evaluation index system was established. Analog computation was carried out to the research programs for poly-generation system using Aspen Plus and Gtpro commercial calculation software, during which performance parameters of each system were obtained, while influence of dynamic and chemical integration on the performance index analyzed, and the performance difference among systems with different configurations compared. Results show that the combination of IGCC and poly-generation system can achieve scale effect, which therefore helps to reduce the unit cost of IGCC and promote the application of this technology. Among all types of methanol-power poly-generation systems, the parallel type system has a higher energy utilization efficiency and net efficiency, in which the energy utilization efficiency of F-class system may reach up to 56%, with a net efficiency up to 40%.
  • Energy System Engineering
    Design Optimization on Initial Temperature Difference of a1 000 MW Ultra-supercritical Direct Air-cooled Unit
    HAN Zhong-he, MA Wu, WANG Zhi
    2013, 33(1): 66-70.
    Abstract ( )   Knowledge map   Save
    Taking the total annual cost of an air-cooled system as the target function, variable condition calculation was conducted to a 1 000 MW ultra-supercritical direct air-cooled unit to compare its total annual costs at different tI values and face velocities, and analyze the change of optimal tI value of the unit with prices of coal and condenser tube bundle and the ambient temperature. Results show that when the tI value is 32 K and the face velocity is 2.2 m/s, the total annual cost of the unit is the lowest. Coal price has the most significant influence on the total annual cost. When the coal price is relatively high, it is suggested that a low tI value be adopted so as to improve thermal efficiency and reduce coal consumption of the unit.
  • Energy System Engineering
    Fault Location on Regenerative System of Turboset Based onStructural Theory of Thermo-economics
    WANG Yong, JI Dong-mei, ZHENG Pu-yan, TANG Hai-ning, LI Xiao-jian
    2013, 33(1): 71-75.
    Abstract ( )   Knowledge map   Save
    Taking the regenerative system of a 600 MW supercritical coal-fired unit as an object of study and introducing the diagnosis model based on structural theory of thermo-economics, the fault indices of a failed component were calculated through thermodynamic simulation model. Based on the diagnosis model and adopting the "Memory" method, the fault source was located by separating the induced fault from the inherent fault. Results show that with features of simplicity, accuracy, and capability of locating the fault component merely by thermo-economic calculations under different boundary conditions, the model can be used as an effective tool for fault diagnosis of thermal systems.
    • Nuclear Technology
  • Nuclear Technology
    Experimental Study on Performance of Moisture Separators
    LU Ming-chao, LI Ya-zhou, XIONG Zhen-qin
    2013, 33(1): 76-80.
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    Visualized separation tests were carried out on air-water two-phase flow in two small-sized moisture separators at normal pressure and temperature. The steam-water separation efficiency and resistance curve of above two separators were measured at different inlet air flows, different volumetric fractions of inlet water and different sizes of inlet water droplets. Results show that for both the separators, obvious water film forms on inner surface of the inner tube, indicating good separation performance under different conditions. For separator 2 with tangential ports, the distribution of separated water at the tangential outlet and in the downward path is greatly affected by both the air and water flows. The total and vane pressure drop of separator 2 are higher than separator 1. The size of inlet droplets basically plays no role in influencing the separation efficiency.