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    Boiler Technology
  • Boiler Technology
    Optimal Simulation on Coal Mill Combination Modes of a Subcritical W-shape Boiler
    MA Lun, FANG Qingyan, TIAN Dengfeng, ZHANG Cheng, CHEN Gang
    2015, 35(7): 517-523.
    Abstract ( )   Knowledge map   Save
    Numerical simulations were conducted to in-furnace flow, combustion, heat transfer and NOx emission characteristics of a 600 MW subcritical W-shape boiler under different coal mill combination modes, so as to compare the simulation results with actual data. Results show that different coal mill combination modes have different effects on the combustion, average residence time of coal particles, burnout rate, NOx emission and temperature distribution near the side walls. In considering the combustion efficiency, the average flue gas at the inlet of the platen superheater and the carbon content in fly ash, the mode with six mills in service is superior to that with five mills in service one mill near the side wall out of service in the reduction of NOx emission, in which case the tendency of slagging near the side walls in lower furnace would be reduced obviously.
  • Boiler Technology
    Multi-objective Optimization of Comprehensive Performance in Boiler Combustion Based on Benefit Model
    ZHOU Jianxin, FANG Xuwen, SUN Liyong, YU Cong, SI Fengqi, XU Zhigao
    2015, 35(7): 524-530.
    Abstract ( )   Knowledge map   Save
    A mathematic model of the multi-objective optimization problem (MOP) in boiler combustion was built and the solution based on improved multi-objective particle swarm optimization (MOPSO) algorithm was presented, while the comprehensive evaluation goal was proposed for the model of boiler combustion considering the economy, environmental protection and energy-saving benefits. Using the improved MOPSO algorithm, the optimization of boiler efficiency, NOx emission and auxiliary electrical consumption was performed, and subsequently a judgment method on the result of multi-objective optimization based on the benefit model was proposed. Results show that the MOPSO algorithm can be used to determine the optimal method of the combustion adjustment.
  • Boiler Technology
    Experimental Study on Resistance Characteristics of Internal Counterflow Wind Caps with Inner Tubes
    FAN Jinlong, SONG Guoliang, SONG Weijian, SUN Yunkai
    2015, 35(7): 531-536.
    Abstract ( )   Knowledge map   Save
    Based on actual wind caps of a 660 MW circulating fluidized bed (CFB) boiler, theoretical analysis and cold-state experiments were conducted to the internal counterflow wind caps with inner tubes, so as to study the effects of following factors on the resistance characteristics, such as the structure size, local resistance, back pressure and arrangement of multi-wind caps, etc., after which a calculation model was obtained for the resistance of wind caps based on a great deal of test data using Levenberg-Marquardt (LM) algorithm and universal global optimization. Results show that the resistance of wind caps is related to both the wind velocity and the structure size, and among all the 5 locations (inner tube, small holes at the head, annular gap, turning position and small holes on inner tube), the resistance from small holes on inner tube plays the most important role. The resistance of wind cap reduces with the rise of back pressure, which is slightly affected by the arrangement of multi-wind caps. The results of wind cap resistance calculated with the model proposed agree well with experimental data.
  • Boiler Technology
    Experiments on Performance of Corrugated-plate Separator in the Drum of Waste Heat Boiler
    HAN Zimo, CHI Zuohe, WANG Jinqing, ZHANG Guangxue, YANG Wen, LUO Fei
    2015, 35(7): 537-542.
    Abstract ( )   Knowledge map   Save
    Cold-state experiments were performed to the no-hook, single-hook and double-hook corrugated-plate separator in the drum of waste heat boiler, so as to study the total separation efficiency, single-stage separation efficiency, inlet droplet size, outlet droplet size and the resistance coefficient at different inlet air velocities. Results show that the corrugated-plate separator with double hooks has the highest total separation efficiency among all the three separators, and their critical film-breaking velocities are 2 m/s, 5 m/s and 7 m/s, respectively; for both the no-hook and double-hook corrugated-plate separator, the single-stage separation efficiency at first three stages is far more than at last three stages; for the single-hook corrugated-plate separator, the single-stage separation efficiency increases significantly at the last three stages with the rise of inlet air velocity, especially at the sixth stage; for all the three separators, the outlet droplet size rises quickly at the critical film-breaking velocity; the resistance coefficient of single-hook corrugated-plate separator is far greater than that of no-hook and double-hook one. Based on overall consideration, the double-hook corrugated-plate separator is proved to have the best performance among all the three types.
  • Boiler Technology
    Study on NO-Char Reaction Characteristics in High-CO2 Concentration Atmosphere
    ZHANG Yongchun, ZHANG Jun
    2015, 35(7): 543-548.
    Abstract ( )   Knowledge map   Save
    Taking Lijiata and Jinjie bituminous char as the object of study, the characteristics of NO-char reaction in high-CO2 concentration atmosphere were investigated in a fixed-bed reactor, so as to analyze the effects of following factors on the NO reduction by char, such as the reaction atmosphere, CO2 concentration, O2 concentration, initial NO concentration and the pyrolysis temperature, etc. Results show that high concentration of CO2 existing in reaction atomphere is detrimental to the NO reduction by char, and with the rise of CO2 concentration, the effect becomes more obvious. At low reaction temperatures, the presence of O2 in reaction atmosphere has a certain promotion effect on the reduction of NO, whereas at high temperatures, it's the opposite. The reduction rate of NO reduces with the increase of initial NO concentration. The reactivity of char decreases with increasing pyrolysis temperature.
    • Automatic Control and Detecting Diagnosis
  • Automatic Control and Detecting Diagnosis
    Research on PID Nonlinear Coordinated Control Based on Dissipative Theory for Ultra Supercritical Units
    GU Junjie, SUN Dalong
    2015, 35(7): 549-555.
    Abstract ( )   Knowledge map   Save
    A new method was proposed to design a PID coordinated controller for ultra supercritical units, by taking dissipative theory as the core idea. Firstly, setting up the nonlinear mathematical model for ultra supercritical units, moving the working point of the units, simplifying the model, introducing integrals to the simplified model, and based on the difference between control input and output, the model was decomposed into two subsystems. Then a PID coordinated controller was constructed using different design methods according to specific situations of each subsystem, which was applied to a 1 000 MW ultra supercritical unit for verification and simulation. Results show that the controller has good effects in given value tracing and disturbance rejection.
  • Automatic Control and Detecting Diagnosis
    Parameter Identification of Turbine Governing System Based on Fruit Fly Optimization Algorithm
    JIANG Xiaolong, WEI Le, SHENG Kai, YAN Yuanyuan,PENG Shuangjian, ZHU Xiaoxing
    2015, 35(7): 556-561.
    Abstract ( )   Knowledge map   Save
    To establish an accurate model of steam turbine governing system for stability calculation of the power system, the fruit fly optimization algorithm (FOA) was applied to identify the parameters of the governing system based on preprocessed field test data of a thermal power plant. Simulation and verification were conducted to the parameters identified, and a comparison was made between simulated and measured curves, following which corresponding error indicators were calculated. Results show that the characteristics of the model obtained by simulation and verification agree well with that of the actual model, proving the method to be practicable and effective.
    • Auxiliary Equipment Technology
  • Auxiliary Equipment Technology
    Application of Adaptive Sequential Optimization Algorithm Based on Kriging Surrogate Model in Design of Centrifugal Compressor Volute
    CAO Anguo, WU Yadong, LIU Pengyin, DU Zhaohui
    2015, 35(7): 562-567.
    Abstract ( )   Knowledge map   Save
    An adaptive sequential optimization algorithm was presented based on improved Kriging surrogate model, while a corresponding optimization platform was developed using Matlab software, with which an aerodynamic optimization design was carried out for a centrifugal compressor volute by taking the total pressure loss coefficient as the target variable. A comparative calculation was made for the compressor volute before and after optimization, so as to verify the applicability of the platform in design of actual compressor volutes. Results show that after optimization, the total pressure loss coefficient is decreased and the static recovery coefficient is increased, resulting in improved performance of the compressor volute.
  • Auxiliary Equipment Technology
    Study on Bed Temperature Distribution and Heat Transfer Performance of Rotary Drum Ash Coolers
    SUN Lijun, LIU Baiqian, TAN Peilai, YAO Jiabin
    2015, 35(7): 568-573.
    Abstract ( )   Knowledge map   Save
    To better interpret the hot ash heat transfer process in rotary drum, the cooling process of hot ash in a water-cooled rotary drum (RD) drained from circulating fluidized bed boiler was investigated at different rotation speeds and ash filling rates, after which optimum ash filling rates were obtained. Results show that there exist a high temperature region in the ash bed, which nearly coincides with the core region of granular flow; along the circumferential direction of ash motion in the passive layer, the ash temperature is approximately uniform on the same particle path line, and the ash bed can be divided into thermostatic strips according to the radial distance of RD wall; the heat transfer rate increases with the rise of ash filling rate, but the increasing gradient is gradually reduced; with the rise of drum rotating speed, the optimum ash filling rate increases first and reduces later on, and at the rotating speed of 5 rpm, the optimum ash filling rate reaches the maximum, i.e. 28.7%.
  • Auxiliary Equipment Technology
    Numerical Study on Tone Noise Source and Noise Radiation Characteristics of Single Stage Axial Flow Fan
    ZHANG Jianhua, CHU Wuli, LIU Wei
    2015, 35(7): 574-580.
    Abstract ( )   Knowledge map   Save
    A numerical simulation on internal unsteady viscosity flow field of single stage axial flow fan was performed using three-dimensional incompressible unsteady Reynolds (UR) average Navier-Stokes equations and RNG k-ε turbulence equations, so as to locate the primary noise source and the reason caused according to flow field analysis results of the rotor/stator interactions, and to study the tone noise radiation characteristics of the fan with FW-H equations based on Lighthill analogy theory coupled with UR analysis results. Results show that the primary source of rotor/stator interaction noise comes from pressure fluctuations at leading edge of the stator, which is caused by periodical interaction on stator leading edge resulted from the upstream rotor wake, tip clearance vortex and a contra-rotating vortex induced by the rotor wake. The tone noise of fan is mainly generated by rotor/stator interaction, in which the BPF component is predominant; the noise is mainly radiated from the duct outlet.
    • Environmental Science
  • Environmental Science
    Growth of Soluble and Insoluble Mixed PM2.5 by Vapor Heterogeneous Condensation
    LI Lin, FAN Fengxian
    2015, 35(7): 581-587.
    Abstract ( )   Knowledge map   Save
    A dynamic model was established for particle growth by vapor heterogeneous condensation, with which the condensation growth of soluble and insoluble mixed particles was investigated using numerical simulation, so as to analyze the influences of operational parameters on the condensation growth. Results show that the higher the number fraction of soluble particles in the mixed PM2.5 is, the smaller the number concentration peak size and the median size of the droplets will be after condensation growth, resulting in more dispersed distribution of the droplet size. The particle size distribution would be significantly changed after condensation growth when soluble particles are mixed into the insoluble PM2.5. The smaller the particle size is, the closer the condensation growth rate of insoluble particles will be to that of soluble particles. When the particle size is greater than 0.3 μm in diameter, the growth rate and final diameter of a soluble particle would be much greater than those of an insoluble particle. The growth rate of the mixed PM2.5 can be promoted by increasing the initial vapor saturation and gas temperature. With the rise of number concentration of PM2.5, the number concentration peak size decreases after condensation, while the particle size distribution becomes less-dispersed.
    • New Energy
  • New Energy
    Reduced-order Models for Unsteady Aerodynamic Load of Wind Turbines
    GUO Qiang, LIU Pengyin, ZHU Xiaocheng
    2015, 35(7): 588-592.
    Abstract ( )   Knowledge map   Save
    For wind turbines that undertake unsteady aerodynamic load in unsteady aerodynamic environment, two reduced-order models (ARMA and Volterra series model) were proposed to predict the unsteady aerodynamic load borne by the turbine airfoil, and the prediction results were compared with that of CFD simulations, so as to verify the predictability of above two models. Results show that ARMA model has stronger predictability under attached flow conditions, while Volterra Series model is more accurate under separated flow conditions. Both the reduced-order models can help to calculate the aerodynamic characteristics of wind turbines under different conditions at very little cost, which therefore may be used for aero-elastic analysis and design optimization of wind turbines.
  • New Energy
    Influence of Trailing Edge Trim on Aerodynamic Performance of the Wind Turbine Airfoil
    YE Zhou, HAO Wenxing, ZU Hongya, LI Chun
    2015, 35(7): 593-598.
    Abstract ( )   Knowledge map   Save
    The S809 and S805 two airfoils with different relative thickness were trimed on the trailing edge, of which the aerodynamic perfomance was calculated by using the analysis and design software Xfoil before and after trimming, so as to study the influence of trailing edge trim in different degrees on aerodynamic performance of the airfoil, and to analyze the flow field characteristics using CFD. Results show that the lift coefficient and the maximum lift-to-drag ratio of airfoil with trimmed trailing edge reduce in attached flow area, and the reducing gradient increases with the trimming degree. The influence of trailing edge trim is different for airfoils with different relative thickness, and in the stall zone, drag coefficient of thicker airfoil decreases, and lift coefficient of thin airfoil increases. The pressure coefficient of airfoil surface is changed by trailing edge trim, and the pressure coefficient of thicker airfoil is changed obviously. The wake disturbance caused by trailing edge trim will extend to other surface, and thus affect the aerodynamic characteristics of the airfoil.
  • New Energy
    A New Design Method for Compound Parabolic Concentrators by Eliminating the Secondary Reflection
    XIE Huling, WEI Jinjia, GAO Yang, ZHAO Liang
    2015, 35(7): 599-604.
    Abstract ( )   Knowledge map   Save
    Mathematic models were set up for the compound parabolic concentrator (CPC), respectively without truncation, with half light truncation and with elimination of secondary reflection. According to ray tracing method and Monte Carlo method, and for the geometric concentrating ratio in the range of 2 to 10, the aspect ratio of CPC depth to outlet aperture width was calculated, and subsequently the CPC economy was analyzed, following which both the non-uniformity of concentrated light and the maximum irradiance on the best uniform surface were computed, so as to study the uniformity of the CPC. Results show that for the same geometric concentrating ratio, the newly designed CPC with elimination of secondary reflection has the best economy and the highest uniformity of concentrated light among all the three types of CPCs mentioned above.