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风力发电就是通过风力机带动发电机发电,发出的交流电供给负载。当负载需用直流电时,可用直流发电机发电或者用整流设备将交流电转换成直流电。发电机是风力发电机组的重要组成部分之一,分为同步发电机和异步发电机两种。以前小型风力发电机用的直流发电机,由于其结构复杂,维修量大,逐步被交流发电机所代替。机组发出的电有两种供给方式:独立供电与并网供电。1发电机(1)同步发电机同步发电机(见图1)主要由定子和转子组成。定子由开槽的定子铁心和放置在定子铁心槽内按一定规律联接成的定子绕组(也叫定子线圈)构成;转子上装… 相似文献
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鸳鸯湖电厂1号发电机为QFSN6602型汽轮发电机,采用水氢氢冷却方式,正常运行时发电机内氢压高于定子冷却水压力;当定子线棒存在裂纹并发生泄露时,将会导致定子冷却水含氢量急剧升高,从而使定子冷却水进入发电机造成发电机烧损.定子冷却水箱安装氢气泄露检测仪,在线检测定子冷却水箱内氢气含量,当氢气浓度达2%时就会报警.讨论了发电机定子冷却水箱内检测仪报警后的原因分析及处理,为同类机组类似故障处理提供参考. 相似文献
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大型汽轮发电机定子线棒的堵塞是水内冷汽轮发电机定子常见的故障之一。叙述了600 MW水氢氢汽轮发电机定子线棒堵塞的故障原因,提出,消除故障的措施。 相似文献
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通过对非洲某国电站发电机的中性点接地方式进行分析,对发电机中性点接地变压器的选型进行了工程计算,指出发电机中性点接地变压器的参数选择须与发电机定子接地保护相配合。在发电机定子绕组绝缘有较高安全系数的情况下,接地电阻的选取应主要满足限制接地故障电流及与定子接地保护配合的需要。 相似文献
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以华电齐齐哈尔热电厂#1机组为例,介绍了300 MW级发电机定子采用单扁担法吊装就位的施工技术措施和就位过程,吊发电机定子用的扁担及钢丝绳等的强度计算,桥吊上卷扬机钢丝绳拉力计算,桥吊轮压校核,300MW级发电机定子吊装用单扁法与双扁担法的经济性对比,以及用单扁担法吊发电机定子的推广情况。 相似文献
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发电机定子接地故障会导致运行中的发电机组严重损坏,传统双频式100%定子接地保护在现代化的发电机保护中已经不能满足要求,外加电源式100%定子接地保护具有不受发电机运行工况和状态的影响、无保护死区、高灵敏的特点将逐步取代传统双频式100%定子接地保护。在Matlab中建立模型,通过仿真分析检验其科学性和合理性。结果证明,外加电源式100%定子接地保护有很高的灵敏度,且没有保护死区,是非常理想的发电机定子接地保护。 相似文献
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刘华钢 《电网与水力发电进展》1995,(2)
本文介绍了自调整式的发电机定子接地微机保护装置的研制及其动摸试验结果,着重介绍了保护装置的硬件结构和软件结构及其主要功能,以及保护装置的可靠性和抗干扰性能,从动模实验上证明了自调整式的发电机定子接地微机保护装置的优良性能,为保护装置的推广应用提供了条件。 相似文献
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许芝草 《电网与水力发电进展》2003,19(4):33-35
介绍了大型水轮发电机的新型冷却方式——蒸发冷却方式在李家峡水电站4#发电机定子绕组中的原理、应用及优点,对李家峡水电站4#发电机定子下线的整个工艺过程、定子下线安装过程中发现的问题及时分析、总结,以及解决的办法。 相似文献
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《International Journal of Hydrogen Energy》2020,45(43):23048-23055
We studied the adsorption of water molecules via the density functional theory on the pure and silicon and/or germanium doped graphene. We investigated the electrostatic surface potential of the structures to predict the possible interactions. Also, we examined the interaction between every possible side of the water molecule and possible sites of the pure and doped graphene. There was no interaction between the water molecule and the graphene. The only interaction was between the oxygen atom of the water molecule and the doped atoms. We also studied the decomposition of the water molecule on these doped graphene sheets and the possible intermediates and transition states and reaction pathway for the decomposition process. We calculated the interaction energies for the adsorption steps and the thermodynamic parameters for all steps of reaction pathway. The results showed that the adsorption of the water molecule on silicon and/or germanium doped graphene. Also, the decomposition of one of the hydrogen atoms of water molecule was thermodynamically favored at room temperature. 相似文献
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Over the years, significant changes have taken place with regard to the type as well the quantity of energy used in Indian households. Many factors have contributed in bringing these changes. These include availability of energy, security of supplies, efficiency of use, cost of device, price of energy carriers, ease of use, and external factors like technological development, introduction of subsidies, and environmental considerations. The present paper presents the pattern of energy consumption in the household sector and analyses the causalities underlying the present usage patterns. It identifies specific (groups of) actors, study their specific situations, analyse the constraints and discusses opportunities for improvement. This can be referred to “actor-oriented” analysis in which we understand how various actors of the energy system are making the system work, and what incentives and constraints each of these actors is experiencing. It analyses actor linkages and their impact on the fuel choice mechanism. The study shows that the role of actors in household fuel choice is significant and depends on the level of factors – micro, meso and macro. It is recommended that the development interventions should include actor-oriented tools in energy planning, implementation, monitoring and evaluation. The analysis is based on the data from the national sample survey (NSS), India. This approach provides a spatial viewpoint which permits a clear assessment of the energy carrier choice by the households and the influence of various actors. The scope of the paper is motivated and limited by suggesting and formulating a powerful analytical technique to analyse the problem involving the role of actors in the Indian household sector. 相似文献
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管壳式废热锅炉整体强度计算具有相当的复杂性,其中管板强度和管板与管子连接强度显得尤为关键。通过建立锅炉整体结构的有限元分析模型,更加全面且贴切地表征了管板、管子分布以及管板与管子连接的真实结构,从而更加详尽而准确地反映了废热锅炉整体的应力应变分布,为科学合理地设计及优化废热锅炉提供了理论指导。 相似文献
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Two important challenges need to be addressed to realize a practical biorefinery for the conversion of biomass to fuels and chemicals: (i) effective methods for the degradation and fractionation of lignocelluloses and (ii) efficient and robust chemical methods for the conversion of bio-feeds to target products via highly selective catalytic reactions. Ultrasonic energy promotes the pretreatment and conversion process through its special cavitational effects. In this review, recent progress and methods for combining and integrating sonication into biomass pretreatment and conversion for fuels and chemicals are critically assessed. Ultrasonic energy combined with proper solvents allows destruction of the recalcitrant lignocellulosic structure, fractionation of biomass components, and then assists many thermochemical and biochemical reactions, with increased equilibrium yields of sugars, bio-ethanol and gas products by 10–300%. Sonication promotes hydrolysis, esterification and transesterification in biodiesel synthesis and leads to reduced reaction time by 50–80%, lower reaction temperature, less amounts of solvent and catalyst than comparable unsonicated reaction systems. For algal biomass, sonication benefits the disruption, lysis and content release of macro and microalgae cells, and reduces the time required for subsequent extraction and chemical/biochemical reactions, with efficiencies typically being improved by 120–200%. High-frequency ultrasound of 1–3 MHz allows harvesting of microalgae, liquid product separation and in-situ process monitoring of biomass reactions, while high-intensity ultrasound at 20–50 kHz activates heterogeneous and enzymatic catalysis of the biomass reactions. The use of ultrasound in conversion of biomass to biofuels provides a positive process benefit. 相似文献
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The development of electric mobility systems with fuel cells is associated with a special constellation of circumstances. The definition of powertrain systems on board electric vehicles is dependent on the refueling infrastructure. At the same time, the development of a hydrogen infrastructure is dependent on vehicle definition and introduction. The joint development of powertrain and infrastructure is a unique opportunity to optimize both the systems. In this paper, we select a number of tradeoffs between the powertrain design and the infrastructure design and calculate technical and financial effects. By way of example we show an optimization of the fuel cell, battery and tank size subject to user behavior and infrastructure constraints. Using powertrain simulations we calculate hybridization ratio and tank size. We then show an exemplary infrastructure layout consisting of transmission and distribution networks. In this paper we consider the infrastructure in Germany by 2030. We then proceed to show the implications of the mutual dependencies between vehicle and infrastructure and to analyze technical potentials and overall system costs. Our main conclusions show ways that could be beneficial for the introduction of electric mobility with fuel cells and a hydrogen infrastructure. 相似文献
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The plugging mechanism of multiphase mixed rich-liquid transportation in submarine pipeline is a prerequisite for maintaining the fluid flow in the pipeline and ensuring safe fluid flow. This paper introduced the common experimental devices used to study multiphase flow, and summarized the plugging progress and mechanism in the liquid-rich system. Besides, it divided the rich-liquid phase system into an oil-based system, a partially dispersed system, and a water-based system according to the different water cuts, and discussed the mechanism of hydrate plugging. Moreover, it summarized the mechanism and the use of anti-agglomerates in different systems. Furthermore, it proposed some suggestions for future research on hydrate plugging. First, in the oil-based system, the effect factors of hydrates are combined with the mechanical properties of hydrate deposit layer, and the hydrate plugging mechanism models at inclined and elbow pipes should be established. Second, the mechanism of oil-water emulsion breaking in partially dispersed system and the reason for the migration of the oil-water interface should be analyzed, and the property of the free water layer on the hydrate plugging process should be quantified. Third, a complete model of the effect of the synergy of liquid bridge force and van der Waals force in the water-based system on the hydrate particle coalescence frequency model is needed, and the coalescence frequency model should be summarized. Next, the dynamic analysis of a multiphase mixed rich-liquid transportation pipeline should be coupled with the process of hydrate coalescence, deposition, and blockage decomposition. Finally, the effects of anti-agglomerates on the morphological evolution of hydrate under different systems and pipeline plugging conditions in different media should be further explored. 相似文献
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Biotechnology in petroleum recovery: The microbial EOR 总被引:1,自引:0,他引:1
Biotechnology has played a significant role in enhancing crude oil recovery from the depleted oil reservoirs to solve stagnant petroleum production, after a three-stage recovery process employing mechanical, physical and chemical methods. Biotechnologically enhanced oil recovery processes, known as microbial enhanced oil recovery (MEOR), involve stimulating indigenous reservoir microbes or injecting specially selected consortia of natural bacteria into the reservoir to produce specific metabolic events that lead to improved oil recovery. This also involves flooding with oil recovery agents produced ex situ by industrial or pilot scale fermentation. This paper essentially reviews the operating mechanisms and the progress made in enhanced oil recovery through the use of microbes and their metabolic products. Improvement in oil recovery by injecting solvents and gases or by energizing the reservoir microflora to produce them in situ for carbonate rock dissolution and reservoir re-pressurization has been enunciated. The role of biosurfactants in oil mobilization through emulsification and that of biopolymers for selective plugging of oil-depleted zones and for biofilm formation have been delineated. The spoil sport played by sulfate-reducing bacteria (SRB) in MEOR has also been briefly reviewed. The importance of mathematical models used in predicting the applicability of an MEOR strategy and the microbial growth and transport has been qualitatively discussed. The results of some laboratory studies and worldwide field trials applying ex situ and in situ MEOR technologies were compiled and interpreted. However, the potential of the MEOR technologies has not been fully realized due to poor yield of the useful microbial metabolic products, growth inhibition by accumulated toxic metabolites and longer time of incubation. A complete evaluation and assessment of MEOR from an engineering standpoint based on economics, applicability and performance is required to further improve the process efficiency for writing more success stories. Thus, this review attempts to address almost all the issues concerning the MEOR, its past and recent trends and its future prospect and directions. 相似文献
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An experimental investigation was conducted to evaluate the effects of using methanol as additive to biodiesel–diesel blends on the engine performance, emissions and combustion characteristics of a direct injection diesel engine under variable operating conditions. BD50 (50% biodiesel and 50% diesel in vol.) was prepared as the baseline fuel. Methanol was added to BD50 as an additive by volume percent of 5% and 10% (denoted as BDM5 and BDM10). The results indicate that the combustion starts later for BDM5 and BDM10 than for BD50 at low engine load, but is almost identical at high engine load. At low engine load of 1500 r/min, BDM5 and BDM10 show the similar peak cylinder pressure and peak of pressure rise rate to BD50, and higher peak of heat release rate than that of BD50. At low engine load of 1800 r/min, the peak cylinder pressure and the peak of pressure rise rate of BDM5 and BDM10 are lower than those of BD50, and the peak of heat release rate is similar to that of BD50. The crank angles at which the peak values occur are later for BDM5 and BDM10 than for BD50. At high engine load, the peak cylinder pressure, the peak of pressure rise rate and peak of heat release rate of BDM5 and BDM10 are higher than those of BD50, and the crank angle of peak values for all tested fuels are almost same. The power and torque outputs of BDM5 and BDM10 are slightly lower than those of BD50. BDM5 and BDM10 show dramatic reduction of smoke emissions. CO emissions are slightly lower, and NOx and HC emissions are almost similar to those of BD50 at speed characteristic of full engine load. 相似文献
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《International Journal of Hydrogen Energy》2022,47(92):39018-39029
Developing a single electrocatalyst effective for both oxygen and hydrogen evolution remains challenging. Although an attempt to utilize a single electrocatalyst for overall water splitting is made, there still exist several issues of efficiency and stability of the electrocatalyst. Hence, the present study reports on morphology-controlled NiO electrocatalyst, a single electrocatalyst for oxygen and hydrogen evolution. The cubic phase NiO nanoparticles and nanoplates of diameter and thickness <10 nm delivered surface-to-volume ratios of 0.078 and 0.083, respectively. XRD and TEM confirm the formation of NiO nanostructures, where morphology transformed independently of the chemical composition. XPS and EXAFS confirm the 2+ oxidation state of Ni ions and its octahedral coordination with oxygen. The 0D nanoparticles providing a larger surface area and active sites offered the overpotentials of 373 and 268 mV for OER and HER activity, respectively, and performed well than the 2D porous NiO nanoplates. The chronoamperometry and repetitive LSV cyclic studies confirmed the excellent long-term stability of 0D NiO nanoparticles in basic and acidic mediums during electrocatalytic water splitting reactions, owing to its increased electrochemically exposed active sites. 相似文献