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Liu H.-G.,Huaneng Yuhuan Power Plant | Liu H.-G.,China Shenhua Energy Company | Li S.-Z.,Shanghai Electrical Power Generation Equipment Co Ltd | Li S.-Z.,Shanghai JiaoTong University | And 3 more authors.
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2015

The precipitation behavior and influence of Laves phase in martensitic heat resistant steel was studied by contrasting the whole martensitic microstructure and the martensitic microstructure which containing a small amount of delta ferrite. The Laves phase was observed by using a transmission electron microscope (TEM), and subsequent analysis is implemented in respect of the precipitation behavior of Laves phase in different microstructure and the influence of creep temperature and stress on the morphology and size of Laves phase. The results show that there are two mechanisms of the nucleation and growth for Laves phase in whole martensitic microstructure, one of which is that Laves phases occur alone on grain boundaries while the other one is that Laves phases are formed in the regions adjacent to M23C6 particles. But in martensitic which contained a few delta ferrite, the Laves phase is nucleated preferentially inside the delta ferrite. The higher creep temperature and stress can promote the nucleation and growth of Laves phase. ©, 2015, Editorial Office of Transactions of Materials and Heat Treatment. All right reserved.

Ma Z.,Tsinghua University | Deng J.,Tsinghua University | Li Z.,Tsinghua University | Li Q.,Tsinghua University | And 9 more authors.
Atmospheric Environment | Year: 2016

Coal combustion in coal-fired power plants is one of the important anthropogenic NOx sources, especially in China. Many policies and methods aiming at reducing pollutants, such as increasing installed capacity and installing air pollution control devices (APCDs), especially selective catalytic reduction (SCR) units, could alter NOx emission characteristics (NOx concentration, NO2/NOx ratio, and NOx emission factor). This study reported the NOx characteristics of eight new coal-fired power-generating units with different boiler patterns, installed capacities, operating loads, and coal types. The results showed that larger units produced less NOx, and anthracite combustion generated more NOx than bitumite and lignite combustion. During formation, the NOx emission factors varied from 1.81 to 6.14 g/kg, much lower than those of older units at similar scales. This implies that NOx emissions of current and future units could be overestimated if they are based on outdated emission factors. In addition, APCDs, especially SCR, greatly decreased NOx emissions, but increased NO2/NOx ratios. Regardless, the NO2/NOx ratios were lower than 5%, in accordance with the guidelines and supporting the current method for calculating NOx emissions from coal-fired power plants that ignore NO2. © 2016 Elsevier Ltd.

Li Y.-C.,Northern Energy Source Development Co. | Yu H.-D.,Northern Energy Source Development Co. | Li Z.-L.,China Shenhua Energy Company | Li F.-Z.,Huaneng Yuhuan Power Plant
Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power | Year: 2015

After the four sets of 1 000 MW unit in Yuhuan Power Plant had been put into operation, under the operating condition at the full load, the opening degree of the water level regulating valve of the deaerator was around 18%. Through a variable frequency modification to the condensate water pump, the pressure in the main line of the condensate water decreased from 3.3 MPa to 2.6 MPa and the opening degree of the regulating valve increased to 60%, thus weakening the throttling effect and the power consumed by the condensate water pump declined by 21%. The authors conducted a theoretical analysis of the principles controlling the energy saving and described the matters needing attention concerning the version selection, commissioning process, logic configuration and operation control etc. during the variable frequency modification to the pump group for reference by others facing similar problems. ©, 2015, Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power. All right reserved.

Huang F.,North China Electrical Power University | Liu S.,North China Electrical Power University | Song W.,North China Electrical Power University | Liu B.-Y.,Huaneng Yuhuan Power Plant
Reneng Dongli Gongcheng/Journal of Engineering for Thermal Energy and Power | Year: 2016

With the purpose of getting more accurate two-dimensional temperature field of furnace flame in order to realize the real-time monitoring of the furnace flame temperature, the optical method and acoustical method are used respectively to model the temperature field reconstruction and deduct the simple matrix inversion formula, meanwhile, the singular value decomposition (SVD) algorithm is also adopted for the reconstruction of the two-dimensional temperature field in furnace. The numerical study shows that when the measuring errors are 0.05 and 0.1, the optical and acoustical measuring methods can obtain good reconstruction results separately in high-temperature region and in lower-temperature region. Hereby, based on the Analytic Hierarchy Process (AHP), the paper puts forward the optical and acoustical combined temperature field reconstruction technology for the two-dimensional reconstruction of furnace unimodal symmetric, unimodal bias and bimodal symmetric temperature fields. The results show that the inversion accuracy can be increased by about 0.01 in comparison of optical method or acoustical method, which proves the feasibility and accuracy of this combined method have the great significance on furnace temperature field inversion. © 2016, Harbin Research Institute. All right reserved.

Yin Z.,Thermal Power Research Institute | Cai H.,Thermal Power Research Institute | Liu H.-G.,Huaneng Yuhuan Power Plant
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2012

Performance and microstructure of a new ferritic heat-resistant steel P92 used in ultra-supercritical unit of Plant for 16000 h was studied by means of tensile and impact tests, scanning electron microscopy(SEM) and EDS analysis, X-ray diffraction(XRD) and transmission electron microscopy(TEM). The results show that the room temperature tensile strength and proof strength at non-proportional extension of the running steel P92 for 16000 h reach 703 MPa and 543 MPa, respectively, which remain at a high level and meet the performance requirement of ASME SA335 P92. The proof strength of the steel at high temperature(600°C) still meets the technical requirement of GB5310 for 10Cr9MoW2VNbBN. The steel exhibits high impact absorption energy values over 160 J, its impact toughness is not significantly reduced after long-term service. The impact fracture reveals ductile fracture characteristics. Relatively uniform equiaxed dimples, in which precipitation particles are observed, are distributed in fibrous region. Precipitates are mainly M23C6 carbides along grain boundaries, and dispersively distributed MX phase, Nb, V (C, N) carbides and relatively stable Laves phase(Fe2W) are also observed.

Yin Z.,Thermal Power Research Institute | Cai H.,Thermal Power Research Institute | Liu H.,Huaneng Yuhuan Power Plant
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2011

Through the analysis of the performance, metallographic, scanning electron microscope (SEM), energy disperse spectrum (EDS), oxide, carbide extraction, and transmission electron microscope (TEM) methods, the aging research of the new austenitic heat-resistant steel HR3C was conducted in ultra-supercritical units after service for 5400 hours and 25000 hours. The research shows that after service for 25000 hours the performance of HR3C changes: the main tensile strength increases by 4%, yield strength decreases by 10%; 650°C tensile properties decrease slightly; it becomes brittle when being crushed, the hardness is increased observably, indicating that aging has taken place to strengthen; a dense oxide layer of Cr2O3 is formed in outer and inner oxide scale; tissue had no significant aging, precipitates are mainly Z-phase, M23C6 and M6C, carbide was obviously precipitated along the grain boundaries; the content of M6C and M23C carbide precipitation after service for 25000 hours is significantly higher than after service for 5400 hours, which showed that a part of M23C6 carbide precipitation had been transformed into M6C carbide precipitation. © 2011 Chinese Society for Electrical Engineering.

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