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    Boiler Technology
  • Boiler Technology
    Experimental Study on Thermal Deviation of Spiral Tube Water Wall for Supercritical Pressure Once-through Tower Boilers
    CHEN Duan-yu, HE Xiang, YANG Yong, ZHANG Fu-xiang, ZHU Cai-guang
    2012, 32(8): 581-585.
    Abstract ( )   Knowledge map   Save
    Taking the 1 000 MW supercritical pressure once-through tower boiler as an example, measurement and calculation have been carried out on the thermal deviation of its spiral tube water wall at varying loads. Results show that the thermal deviation changes with the variation of unit load, the higher the load, the smaller the thermal deviation; the thermal deviation factor tends to be 1 at full load. For the combined water wall, made up of upper vertical tube bank and lower spiral tube coil, the thermal deviation is smaller than that of single vertical tube bank. The application of spiral tube water wall is beneficial to improvement of in-furnace thermal load distribution.
  • Boiler Technology
    Calculation and Variation of Heat-transfer Coefficient of Platen Heating Surfaces in a 300 MW CFB Boiler
    WU Hai-bo, ZHANG Man, SUN Yun-kai, L Qing-gang
    2012, 32(8): 586-590.
    Abstract ( )   Knowledge map   Save
    According to the test data obtained on site of a 300 MW CFB boiler and previous research achievements concerning heat-transfer coefficients of CFB boilers, a heat-transfer model of platen heating surface at flue gas side was established, including a radiation heat-transfer model and a semi-empirical formula of convection heat transfer. Based on heat-transfer coefficient calculation of platen heating surface on a 300 MW CFB boiler at 94% boiler maximum continue rate(BMCR) load, the impact of following factors on the heat-transfer coefficient was analyzed, such as the tube pitch of platen heating surface, the furnace temperature, the steam temperature, the emissivity of tube wall and the flue gas velocity, etc. Analysis results show that the flue gas velocity, the furnace temperature and the emissivity of tube wall are the leading factors influencing the heat-transfer coefficient. The heat-transfer model can reasonably reflect how the main factors affect the heat transfer of platen heating surface of CFB boilers.
  • Boiler Technology
    Simulation Methods for Gas-phase Flow Field of Cyclone Separator in Steady or Unsteady State
    ZHAO Tong, YANG Ya-ping, LIU Jun-long
    2012, 32(8): 591-597.
    Abstract ( )   Knowledge map   Save
    To study the characteristics of gas-phase flow field in a gas-solid cyclone separator, numerical simulation and calculation were performed on the flow field in the steady and unsteady state using Reynolds stress model, by adopting multi-block hybrid grid for the separator and different schemes for discretization of advection terms, after which the simulated results were compared with experimental data. Results show that for simulation of gas-phase flow field in a cyclone separator in the unsteady state, the best choice is to choose the second order upwind (SOU) scheme for momentum equations, the Quick scheme for kinetic energy and its dissipation rate, and the first order upwind (FOU) scheme for Reynolds stresses.
    • Steam Turbine and Gas Turbine
  • Steam Turbine and Gas Turbine
    Research on Life Data Management System for Suspended Samples of Important Turbine Wearing Parts
    YANG Yu, SHI Jin-yuan, MO Jing-fei
    2012, 32(8): 598-601.
    Abstract ( )   Knowledge map   Save
    An introduction is being presented to life prediction models for suspended samples of important wearing parts of steam turbines, together with an explanation to methods of the Weibull distribution examination, parameter estimation and life prediction of the suspended samples, as well as a description to the determination of the reliability, reliable life, average life, replacement cycle and detecting cycle of the key wearing components, including some application examples. Functions of the life data management system for wearing parts of steam turbines are simultaneously explained. With the life prediction model, method and life data management system, not only technical basis can be provided for the overhaul of steam turbines, but also the status of important wearing parts can be controlled within the service life.
  • Steam Turbine and Gas Turbine
    Study on Bearing Support Stiffness of LP Rotor for a 1 000 MW Nuclear Power Half-speed Turbine-Generator Set
    WANG Xiu-jin, SUN Qing, LI Wang-fan, WEI Qi, GE Qing
    2012, 32(8): 602-605.
    Abstract ( )   Knowledge map   Save
    A finite element model was established for ground standing type bearing support of LP rotor for a 1 000 MW nuclear power half-speed turbine-generator set with spring foundation, with which the support stiffness was analyzed using 3D finite element software Ansys. Effects of the support stiffness on critical speed of the LP rotor were calculated and analyzed on the basis of above stiffness analysis. Results show that the value of bearing support stiffness calculated with the model is different from but in same order of maganitude with that of empirical value. The critical speed of LP rotor is greatly affected by the bearing support stiffness lower than a certain value, therefore for safety operation purposes, the bearing supports should be designed with higher stiffness.
    • Automatical Controlling and Detecting Diagnosis
  • Automatical Controlling and Detecting Diagnosis
    Nonlinear Mathematical Model and Dynamic Simulation of Scroll Expanders
    HOU Guo-lian, HU Guo-qiang, BI Shan-shan, ZHANG Jian-hua
    2012, 32(8): 606-611.
    Abstract ( )   Knowledge map   Save
    To accurately design the control system of scroll expander, two groups of nonlinear differential equations were established resptively between the valve opening and inlet pressure, as well as between the internal power and rotating speed, based on mechanism analysis of the expander and static mathematical relationships among the inlet pipe, inlet chamber, expansion chamber and exhaust chamber, etc. By analyzing the relations between the inlet pressure and internal power, a dynamic model was obtained between the valve opening and rotating speed. Simulation results show that the dynamic behavior of the model is in good accordance with that of the scroll expander, which proves the model to be accurate and effective.
  • Automatical Controlling and Detecting Diagnosis
    Automation of Numerical Simulation on One-way Fluid-structure Interaction of Fluid-filled Pipeline
    CHEN Jian-hong, ZHOU Tian-qing, SHENG De-ren, LI Wei, CHEN Hui
    2012, 32(8): 612-616.
    Abstract ( )   Knowledge map   Save
    According to the fact that the process of numerical simulation on one-way fluid-structure interaction of fluid-filled pipeline is complex, and the data transferred in calculation is not exact, a simulation program has been compiled using C++ language to automatically implement the model building, fluid calculation and structure analysis, with which the automation of numerical simulation on one-way fluid-structure interaction of fluid-filled pipeline is realized, and the authenticity of the data transferring is ensured. The calculation results of this program are verified by relevant experimental data in references. Taking the drain pipeline in a power plant as an object of study, numerical simulation is performed on the one-way fluid-structure interaction, including automatically building the pipeline model, simulating the pressure distribution of fluid inside the pipeline and analyzing the stress in the pipeline by introducing fluid pressure data to the calculation. Calculation results show that the program previously compiled is accurate in calculation and facile in operation, which is therefore suitable for design, retrofit and risk prediction of fluid-filled pipeline.
    • Engineering Thermophysics
  • Engineering Thermophysics
    Characteristic Study on Pulverized Coal Combustion and NO Formation Under Air Enrichment Conditions
    WANG Chun-bo, LU Hong-yu, LEI Ming, XING Xiao-na
    2012, 32(8): 617-622.
    Abstract ( )   Knowledge map   Save
    Combustion characteristics of pulverized coal under air enrichment conditions were studied and compared with that under oxy-fuel conditions by thermo-gravimetric analysis, while the NO formation rate measured using fixed-bed reactor, so as to analyze the influence of reaction atmosphere and coal category on the NO formation. Results show that with the rise of oxygen concentration, the combustion characte-ristic curves of pulverized coal move to lower temperature regions, and the comprehensive combustion characteristic index S increases; at same low oxygen concentrations, the characteristics of air enrichment combustion are better than oxy-fuel combustion due to different physical properties of N2 and CO2, however, when the oxygen concentration gets up to 40%, the advantage of air enrichment combustion becomes not obvious; both the reaction atmosphere and coal category play a role in influencing the NO conversion rate; the reaction temperature increases with rising oxygen concentration or with participation of N2, and hence affecting the NO conversion rate; the volatile content and the mass fraction of element N also affect the NO conversion rate.
  • Engineering Thermophysics
    Numerical Analysis of Gas-Solid Two-phase Flow in a Composite Burner Made up of Elbow and Venturi Tube
    YANG Mo, KANG Zhang-yang, GUO Chun-sun
    2012, 32(8): 623-628.
    Abstract ( )   Knowledge map   Save
    The characteristics of rich-lean separation in a composite burner made up of elbow and Venturi tube has been numerically simulated, so as to analyze how the particle size and concentration of pulverized coal influence the rich-lean separation behavior at the burner outlet. Results show that the composite burner may not only help to realize rich-lean separation of coal, but also make the coal powder of high concentration flowing away from the wall surface, i.e. realizing coal delivery in the centrally-fuel-rich mode. For coal particles of size 10 μm, the effect of rich-lean separation is not obvious; for coal particles of size 50 μm, better rich-lean separation effect can be achieved, in which case the maximum concentration increases with rising St number; for coal particles of size 100 μm, more cores of concentration will occur with the rise of St number.
    • Auxiliary Equipment Technology
  • Auxiliary Equipment Technology
    Application of Rapid Spray-Freezing Technology in the Anti-icing of Circulating Cooling Towers
    GUO Min-chen, MA Ying, MEI Yong, CHEN Wen-fei, WANG Bo-ping
    2012, 32(8): 629-633.
    Abstract ( )   Knowledge map   Save
    To realize the anti-icing purpose for power plant cooling towers in northern China, a rapid spray-freezing technology is proposed. By comparing the cooling tower adopting the rapid spray-freezing technology with that protected by suspension windshields, the former one is found to be more superior to the latter one in the adjustment of circulating water temperature and in the anti-icing protection of cooling tower. Results show that with the rapid spray-freezing technology, the circulating water temperature may be adjusted automatically to optimal data according to the variation of both the environmental temperature and the unit load, which therefore makes it possible for the unit to safely and economically operate during days of bitter cold or with sudden change in weather.
  • Auxiliary Equipment Technology
    Analysis on Factors Influencing Outlet Water Temperature of Natural Draft Cooling Tower Based on Enthalpy Difference Method
    LI Qi-fen, ZONG Tao, ZHANG Zhi-chao, HU Dan-mei
    2012, 32(8): 634-638.
    Abstract ( )   Knowledge map   Save
    Using enthalpy difference method, a calculation model for outlet water temperature of a natural draft cooling tower was set up, with which factors influencing the outlet water temperature were studied by integrating the condenser and the cooling tower as a whole. Results show that both the inlet and outlet water temperature are influenced by cooling water flow, air velocity at packing section, steam load of condenser and relative humidity of air, and the effect on inlet water temperature is greater than that on outlet water temperature.
  • Auxiliary Equipment Technology
    Study on Separation Performance of Gypsum Hydro-cyclone in Wet Limestone-Gypsum FGD Systems
    SHEN Guo-qing, YANG Ya-long, AN Lian-suo, CAO Ya-xian
    2012, 32(8): 639-646.
    Abstract ( )   Knowledge map   Save
    To improve the separation efficiency, limestone utilization and final product quality of a wet limestone-gypsum FGD system, and reduce the auxiliary power consumption rate of the power plant, an expermiemtal study was performed for optimization of the separation performance of the gypsum hydro-cyclone, by analyzing the influence of cyclone’s structure and operating parameters on the separation efficiency. Results show that for improvement of separation efficiency of gypsum hydro-cyclones, it is effective to adopt higher inlet pressure, moderate wall thickness and inside diameter of overflow pipe, higher insertion depth of overflow pipe, and tapered Archimedean helix inlet.
    • Environmental Science
  • Environmental Science
    Experimental Study on Defluorination of Desulphurization Wastewater and the Process Optimization
    XU Hong-jian, WANG Shu-fang, PAN Wei-guo, GUO Rui-tang, DAI Ling-zhi, WANG Yang
    2012, 32(8): 647-653.
    Abstract ( )   Knowledge map   Save
    An experimental study on defluorination process of desulphurization wastewater was carried out in a static testing apparatus based on combination of chemical coagulation and precipitation method, during which factors influencing the defluorination efficiency were analyzed by orthogonal tests. Results show that the defluorination property of calcium chloride is better than that of the calcium hydroxide, and the best n(Ca)/n(F) is 1∶1.3; adding an appropriate amount of coagulants may help to improve the defluorination property, such as some aluminum sulfate and iron chloride, and the best ratios of n(Al)/n(F) and n(Fe)/n(F) are respectively 1.5 and 0.6; the defluorination efficiency may get up to 95% under the premise of pH value in 5-6, temperature at 30 ℃, rotating speed at 500 r/min, and an addition of 0.1% PAM. Factors influencing the defluorination efficiency are found to be in following descending order: CaCl2, Al2(SO4)3, PAM, FeCl3, pH value ,temperature and rotating speed.
  • Environmental Science
    Formation and Emission Control of PCDD/Fs from Typical Fluidized Bed MSW Incinerators
    WU Hai-long, XIAO Hui-ping, WANG Wu-zhong, ZHANG Yun-qing, JIANG Xu-guang, LI Xiao-dong
    2012, 32(8): 654-660.
    Abstract ( )   Knowledge map   Save
    To evaluate the effects of operation conditions on formation and emission of PCDD/Fs from fluidized bed municipal solid waste (MSW) incinerators, the PCDD/Fs samples taken from different areas of four typical fluidized bed incinerators with different treatment capacities were analyzed and studied. Results show that the combustion temperature plays a role in influencing the PCDD/Fs formation, but it is not the main influencing factor for final emission of PCDD/Fs. The PCDD/Fs, formed in heterogeneous reaction at low temperature during flue gas passing through the purification devices, contributes to the overall emission of PCDD/Fs. The service age of bag filters is a key factor highly affecting the PCDD/Fs emission. New bag filters are quite effective on control of PCDD/Fs emission, but aged bag filters have poor and even negative effect in PCDD/Fs removal, due to its "memory effect".