Archive

  • Select all
    |
    Boiler Technology
  • Boiler Technology
    Study on In-furnace Flow and Combustion Characteristics of a 350 MW MBEL W-shaped Flame Boiler
    LIU Chunlong, ZHAO Peng, HU Richa, GUO Liang, ZHANG Xusheng, HUANG Yong, KUANG Min
    2015, 35(8): 605-612.
    Abstract ( )   Knowledge map   Save
    Cold-state airflow tests at different staged-air ratios (14%, 20% and 25%) and industrial-size hot-state experiments at different staged-air damper openings (25%, 35% and 45%) were respectively performed in a 1∶15-scaled model furnace and in a real furnace of a 350 MW MBEL W-shaped flame boiler. Results show that a deflected flow field would form in the model furnace under all the cold-modeling conditions, with the downward airflow near front wall penetrating deeper than that near rear wall, and with the rise of damper opening, the deflecting degree would get higher; whereas, under all the three conditions with different damper openings, an asymmetrical combustion pattern is to appear in the rear furnace, where the level of gas temperature near front wall would be clearly higher than that near rear wall, deviating from the designed concept of symmetrical W-shaped flame. To keep a high level of burnout rate, the NOx emission may reach 1 594-1 707 mg/m3, due to the high in-furnace gas temperature, large space of lower furnace and low level of staged-air combustion. Comprehensively considering the results of both the modeling test and the industrial-size experiment, the damper opening is recommended to be 35%, when the corresponding staged-air ratio is 18%.
  • Boiler Technology
    Effects of AAEM on Reactivity of the Coal During WetRecycle Oxy-fuel Combustion
    SI Mengting, YU Dunxi, CHEN Jun, XU Minghou
    2015, 35(8): 613-618.
    Abstract ( )   Knowledge map   Save
    By isothermal thermo-gravimetric analysis, the effects of typical alkali and alkaline earth elements (AAEMs) Na and Ca on reactivity of the coal were investigated under various wet recycle oxy-fuel combustion conditions. Results show that the existance of water vapor accelerates the coal combustion under wet recycle oxy-fuel combustion conditions respectively with φ(O2) = 21%, 27% and 32% at 800 ℃ and 900 ℃; and the reactivity of coal increases with the rise of water vapor concentration. Both Na and Ca catalyze the gasification and oxidation reaction, thus improving the coal combustion rate, and the catalytic effect of Ca is superior to Na. Under low concentration conditions, the catalytic effect of Na increases with the rise of its concentration, which, however remains basically unchanged under high concentration conditions.
  • Boiler Technology
    Investigation on Combustion Characteristics of Pulverized Coal in High-temperature Low-oxygen Atmosphere
    WANG Chunbo, QIAO Musen, LEI Ming
    2015, 35(8): 619-624.
    Abstract ( )   Knowledge map   Save
    Combustion characteristics of pulverized coal were studied on self-made bench which could achieve thermal gravimetric measurement at constant temperatures in simulated furnace flue gas atmosphere (i.e. high-temperature low-oxygen atmosphere). Results show that in the constant temperature environment, the weight loss curve of pulverized coal has a turning point, and with the decrease of coal rank, this phenomenon becomes more obvious. The pulverized coal burns strongly at 1 500 ℃, and the burnout time at 900 ℃ is 6 times of that at 1 500 ℃; temperature has little influence on the early stage of combustion above 1 300 ℃. For the same rise rate of oxygen concentration, the increasing degree of weight loss rate at 1 300 ℃ is smaller than at 800 ℃. The effect of water vapor volume fraction on the promotion of coal devolatilization and combustion would be more obvious in the early stage of combustion when the water vapor volume fraction gets up to 10%. The weight loss rate would be reduced if the volume fraction of CO2 is kept to be raised after having got up to 15%.
    • Automatic Control and Detecting Diagnosis
  • Automatic Control and Detecting Diagnosis
    Research on Main Steam Pressure Control of Supercritical CFB Boilers
    GAO Mingming, YUE Guangxi, LEI Xiujian, LIU Jizhen,ZHANG Wenguang, CHEN Feng
    2015, 35(8): 625-631.
    Abstract ( )   Knowledge map   Save
    By analyzing the dynamic characteristics, energy balance, burning carbon and main steam pressure control of supercritical circulating fluidized bed (CFB) boilers, a soft-sensing model was established based on mechanism analysis by reasonably setting relevant key parameters, so as to calculate the amount of burning carbon storage and heat storage in the furnace, and thus obtaining the heat signal in the boiler. The control strategy of energy balance was then applied in the main steam pressure control of a supercritical CFB boiler. Results show that the method can help to stabilize the main steam pressure, enhance the adaptability to load change and improve the control quality of the unit, proving both the model established and the method proposed to be effective.
  • Automatic Control and Detecting Diagnosis
    T-S Fuzzy Linearization for Nonlinear Dynamic Model of WTGS
    HU Yang, LIU Jizhen, LIN Zhongwei
    2015, 35(8): 632-638.
    Abstract ( )   Knowledge map   Save
    For the nonlinear dynamic model of wind turbine generation system (WTGS) with variable-speed variable-pitch (VSVP) techniques, the Takagi-Sugeno (T-S) fuzzy modeling theory was adopted to deal with its nonlinearity to obtain the control design model with high accuracy in linear form. Firstly, the external variables representing the variable condition characteristics of WTGS were extracted as the varying parameters and a class of affine nonlinear parameter varying (ANPV) model was abstracted theoretically. Subsequently, a kind of homogeneous linear Takagi-Sugeno (T-S) fuzzy modeling procedure was applied on ANPV model and the linear parameter varying (LPV) T-S fuzzy model was obtained. Then, the nonlinear dynamic model of WTGS can be dealt with using above T-S fuzzy linearization approaches. Finally, simulations were conducted to demonstrate the approximation performance of the LPV T-S fuzzy model about the nonlinearity of WTGS. Results show that the approximation accuracy of LPV T-S fuzzy model to the nonlinearity of WTGS can be efficiently adjusted by changing the input space partitioning of the premise variables.
  • Automatic Control and Detecting Diagnosis
    Health Degradation Assessment for Turbine-driven Feed Water Pump Based on Orthogonal Locality Preserving Projection and Self-organizing Map
    DONG Yuliang, SU Ye, WANG Hao, SONG Ying, GU Yujiong
    2015, 35(8): 639-645.
    Abstract ( )   Knowledge map   Save
    Aiming at the problem that the operational condition and condition information of turbine-driven feed water pump are complex and its health degradation is difficult to be assessed, a health degradation assessment method was proposed based on orthogonal locality preserving projection (OLPP) and self-organizing map (SOM) by considering the high-dimensional and nonlinear features of the health state and using OLPP algorithm to extract the state features, following which a multi-feature fusion health degradation assessment model was established based on SOM. In the model, minimum quantization error was used as the index of health degradation assessment, and the alarm limit of health degradation was simultaneously determined. The method was then used to assess the health condition of a turbine-driven feed water pump for a 600 MW steam turbine unit before failure trip. Results show that this method can help to detect the health degradation of the turbine-driven feed water pump before failure occurrence, which therefore can be used for early warning of potential failure, and may serve as a reference for arrangement of operation and maintenance schedules.
  • Automatic Control and Detecting Diagnosis
    Application of ART2 Neural Network Combined with C-means Clustering in Fault Diagnosis of Wind Turbine Gearbox
    LI Zhuang, LIU Yibing, MA Zhiyong, TENG Wei
    2015, 35(8): 646-651.
    Abstract ( )   Knowledge map   Save
    An unsupervised learning classification method by using adaptive resonance theory 2 (ART2) neural network combined with C-means clustering was proposed for fault diagnosis of wind turbine gearbox group. For operation data of gearboxes in a wind farm, ART2 neural network was used to preliminarily classify the samples, and subsequently C-means clustering algorithm was used to modify the classification results of ART2 neural network, and the final classification results were compared with those of ART2 neural network. Results show that the proposed method has higher accuracy than traditional ART2 neural network, since it solves the problem of low classification accuracy caused by hard competition of ART2, which therefore can identify the faulted gearbox accurately.
    • Engineering Thermophysics
  • Engineering Thermophysics
    Effects of Particle Properties on Separation Behavior of Differently-sized Non-spherical Particle Mixtures
    TAO He, ZHONG Wenqi, ZHANG Yong, YANG Pin
    2015, 35(8): 652-658.
    Abstract ( )   Knowledge map   Save
    Multi-element particle model was used to describe three kinds of non-spherical particles, including the corn-shaped particle, ellipsoidal particle and cylindrical particle, etc., so as to analyze their collision mechanism, set up motion equations, verify the model reliability through experimental tests, and to study the effects of particle properties on separation behavior of the differently-sized non-spherical particle mixtures. Results show that great difference of separation exists among differently-shaped particles. The segregation extent of ellipsoidal particles is the largest, and that of spherical particles is the smallest, which increases significantly with the diameter ratio. However, the density ratio affects little on the separation behavior of non-spherical particle mixtures.
    • Environmental Science
  • Environmental Science
    Effects of Organic Acid Additives on Enhancement of Carbide Slag Flue Gas Desulfurization
    XU Hongjian, LI Haoran, SUN Sijuan, JIN Jizhao, WANG Meixia, PAN Weiguo
    2015, 35(8): 659-665.
    Abstract ( )   Knowledge map   Save
    Carbide slag and limestone slurry flue gas desulfurization tests were conducted in a bubbling reactor to study the effects of three organic acid additives on the pH buffer capacity, desulfurization efficiency and utilization rate of the carbide slag. Results show that the carbide slag slurry has a pH buffer capacity far lower than limestone slurry; the addition of organic acid additives prolongs the time period in which high desulfurization efficiency is maintained, and citric acid has the strongest enhancing effect among the three additives under same conditions, followed by adipic acid and tartaric acid.
    • New Energy
  • New Energy
    Effect of Relative Flap Length on Aerodynamic Performance of the Airfoil
    ZU Hongya, LI Chun, LI Runjie, YE Zhou, LIU Tianliang
    2015, 35(8): 666-673.
    Abstract ( )   Knowledge map   Save
    Taking the NCA0018 airfoil as the benchmark airfoil, the effects of relative flap length (0.2, 0.3 and 0.4) and relative slot width (1.0%, 1.5% and 2.0%) on the airfoil flow field and resistance properties were numerically studied using Fluent software, with focus on the effects of relative flap length on the airfoil areodynamic performance. Results show that the existance of flap helps to not only improve the airfoil stall characteristics, but also improve the aerodynamic performance of the airfoil, due to its impact on development and variation of the main vortex around the airfoil. For flap airfoil, the stall angle of attack within the scope of study is greater than that of the benchmark airfoil, and when the angle of attack is less than the stall angle of attack, the lift coefficient of flap airfoil will be less that of the benchmark type, and both the drag coefficient and the maximum lift coefficient will be higher than benchmark airfoil. The stall angle of attack reduces gradually with the rise of reltive flap length. When the angle of attack is close to the stall angle of attack, the lift coefficient increases first and reduces later on. For a certain length of flap, the lift coefficient reduces with the rise of relative slot width.
    • Energy System Engineering
  • Energy System Engineering
    An Optimized System for Clean, Efficient and Deep Utilization of Flue Gas Waste Heat from Coal-fired Power Plants
    HAN Yu, XU Gang, YANG Yongping, XU Cheng, SONG Xiaona
    2015, 35(8): 674-680.
    Abstract ( )   Knowledge map   Save
    For clean, efficient and deep utilization of flue gas waste heat from coal-fired power plants, an optimized system based on fluoroplastic heat exchanger technology was proposed, which is composed of two-stage MGGHs and two-stage low-temperature economizers. By thermal performance and techno-economic analysis, advantages of the optimized system were analyzed. Results show that, compared with both the pre-positioned and post-positioned MGGH system, the optimized system previously proposed presents great energy-saving effects and perfectly realizes the cascade utilization of the flue gas waste heat. In terms of economic performance, the proposed system has great benefit while low investment cost since the heat transfer temperature difference and heat exchange area of the heat exchanger are controlled in a rational range.
  • Energy System Engineering
    Research on Co-gasification Characteristics of Biomass Char and Coal
    XIA Guangbi, PIAO Guilin, ZHANG Jubing, XIE Hao, LI Shuai
    2015, 35(8): 681-686.
    Abstract ( )   Knowledge map   Save
    Co-gasification characteristics of biomass char and coal were studied by non-isothermal thermogravimetric analysis. Results show that no matter pine char or straw char is added, both the DTG peak temperature and the end temperature of XQ coal gradually shift to the low temperature area with the rise of blending ratio of the biomass char. The addition of biomass char hardly affects the gasification efficiency of SH coal, which therefore can partially replace the high quality coal, so as to reduce the energy consumption and CO2 emission. Straw char is more helpful to XQ coal gasification in comparison with pine char, as it enables XQ coal to have a lower reaction activation energy, higher frequency factor and more apparent pore distribution.
    • Nuclear Technology
  • Nuclear Technology
    Uncertainty Evaluation of Evaporation Dimensionless Parameters Obtained in Performance Test of a PCCS and the Application
    SUN Liuli, YANG Xiang, ZHAO Ruichang, LIU Yunyan, CHANG Lei, ZHOU Mingzheng
    2015, 35(8): 687-693.
    Abstract ( )   Knowledge map   Save
    A detailed model was developed for uncertainty evaluation on evaporation parameters of passive containment cooling systems (PCCSs), which was applied in calculation and analysis of the external evaporation parameters obtained in a specific performance test. Results show that the uncertainty of evaporation parameters is about 10% within the test accuracy available and the test period concerned; the mass flow rate of steam released in the containment affects most on the final uncertainty, followed by the inlet and outlet mass flow rate of cooling water. The final uncertainty of evaporation parameters can be effectively reduced by improving the measurement accuracy of above parameters.