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Yan Z.G.,China Agricultural University | Cui T.,China National Water Resources and Electrical Power Materials and Equipment Co. | Zhou L.J.,China Agricultural University | Zhi F.L.,China Agricultural University | Wang Z.W.,Tsinghua University
IOP Conference Series: Earth and Environmental Science | Year: 2012

Hydroelectric generator unit is a complex mechanical system which is composed of hydraulic turbine and electric generator. Rotary system is supported by the bearing bracket and the reinforced concrete structures, and vibration problem can't be avoided in the process of operating. Many large-scale hydroelectric units have been damaged because of the vibration problem in recent years. As the increase of the hydraulic turbine unit capacity and water head, the safe operation of hydraulic turbine has become a focus research in many countries. The operating characteristics of the hydraulic turbine have obvious differences at different working conditions. Based on the combination of field measurement and theoretical calculation, this paper shows a deep research on the safe operation of a large-scale Francis turbine unit. Firstly, the measurements of vibration, swing, pressure fluctuation and noise were carried out at 4 different heads. And also the relationships between vibrations and pressure fluctuations at different heads and working conditions were analysed deeply. Then the scientific prediction of safe operation for the unit at high head were done based on the CFD numerical calculation. Finally, this paper shows the division of the operating zone for the hydroelectric unit. According to the experimental results (vibrations, swings, pressure fluctuations and noise) as well as the theoretical results, the operating zone of the unit has been divided into three sections: prohibited operating zone, transition operating zone and safe operating zone. After this research was applied in the hydropower station, the security and economic efficiency of unit increased greatly, and enormous economic benefits and social benefits have been obtained. © Published under licence by IOP Publishing Ltd. Source


Zhou L.,China Agricultural University | Xu H.,Zhejiang Zhongshui Hydropower Equipment Co. | Cui T.,China National Water Resources and Electrical Power Materials and Equipment Co. | Wang Z.,Tsinghua University
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2011

The rehabilitation projects have a huge market in China. In these projects, the flow rates of the turbines are always increased to increase the output. Since the buried parts and the rotational speed keep unchanged, the increase of flow rate will raise hydraulic loss in the whole flow path, thus may decrease the efficiency. In this paper, the hydraulic losses in spiral casing, stay vanes and guide vanes and their effects on the output and efficiency are analyzed. A method is proposed to evaluate the flow rate and guide vane opening for the refurbished turbines. As an example, the hydraulic losses in buried parts of a real case are calculated through flow simulations and the efficiency of the refurbished turbine is evaluated based on these results. Modification of the guide vane profile is suggested for higher efficiency with less flow rate increase. © Copyright. Source


Xie H.,Nanjing Southeast University | Xiong Y.,Nanjing Southeast University | Zheng S.,China National Water Resources and Electrical Power Materials and Equipment Co. | Shi Z.,Nanjing Southeast University | Zhang J.,Nanjing Southeast University
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2011

The ammonia/urea solution wet desulfurization and denitrification technology has low denitration efficiency in industrial application. In this study, the performance of simultaneous removal of SO 2 and NO x by the aqueous urea/ammonium ion/additive solution in a bubbling reactor was investigated, and the ions concentration and pH values of the solution after absorption was analyzed. The results show that the oxidation of NO by O 2 in the gas phase is the dominant mechanism of NO x removal by the aqueous urea/ammonium ion solution. The additive has no catalytic effect on NO absorption without the presence of O 2, and the presence of SO 2 promotes the NO absorption. The experimental results indicate that the reaction mechanism and the effect concerning NO removal by various additives are different. The alkanolamines additive has buffer and catalytic effects, and the mixing alkanolamines additive works better. However, the SO 2 absorption is in competition with the NO removal in the aqueous urea solution with KMnO 4. Under the experimental condition, the NO removal efficiency is lowest in the ammonia/water solution, and highest in the urea solution. The urea could prevent the nitrous acid from decomposing into NO, and the pH of the absorption solution decreases obviously while adding ammonium bicarbonate, which is unfavourable to NO x removal. Source


Wu Z.-Q.,North China Electrical Power University | Wu Z.-Q.,China National Water Resources and Electrical Power Materials and Equipment Co. | Zhou S.-X.,North China Electrical Power University | An L.-S.,North China Electrical Power University
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2011

To meet the strategy demand of energy structural adjustment and configuration optimization, and based on the second law of thermodynamics, influence of fuel quality on the second law efficiency by thermodynamics was analyzed, while fuel exergy of typical energy resources analyzed and evaluated. Results show that the higher the fuel quality (exergy) is, the less the fuel will be consumed for power generation. Standard coal coefficients of different fuels based on the second law of thermodynamics are presented, which may serve as a theoretical foundation for adjustment and configuration optimization of energy structure. Source


Wu Z.,North China Electrical Power University | Wu Z.,China National Water Resources and Electrical Power Materials and Equipment Co. | Zhou S.-X.,North China Electrical Power University | An L.-S.,North China Electrical Power University | Shi H.-L.,North China Electrical Power University
Dongli Gongcheng Xuebao/Journal of Chinese Society of Power Engineering | Year: 2010

Based on previous studies, factors influencing the decision-making process of energy saving and emission reduction are analyzed at three levels, while three typical production patterns of energy-consuming products simultaneously discussed, with focus on statistics method and analysis model of their specific fuel consumption. Moreover, an evaluation on various methods of energy saving and emission reduction is made on the basis of specific fuel consumption of relevant end products. This may serve as a reference for scientifically building evaluation systems of energy saving and emission reduction. Source

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