Impact of NOx Emissions Released from a Gas Turbine-Based Power Plant on the Ambient Air Quality

The number of gas turbine- (GT-) based power plants is rapidly increasing to meet the world’s power demands. Until a few years ago, fossil fuel, and specifically fuel oil, was considered the major energy source for gas turbine operation. Due to the high amount of pollution that fuel oil generates, natural gas has become a popular source of energy due to its lower emissions compared to fuel oil. As a result, many GTs have switched to natural gas as an alternative to fuel oil. However, pollutants expelled from GT-based power plants operating on natural gas impact surrounding air quality. The objective of this study was to examine the dispersion of nitrogen oxides (NO_x) emitted from a GT-based power plant located in the Sultanate of Oman. Supported by CALPUFF dispersion modeling software, six scenarios were investigated in this study. The first four scenarios considered a case where the GT-based power plant was operating on natural gas during winter and summer and for open and combined cycle modes. The remaining two scenarios considered, for both open and combined cycle modes, the case where the GT-based power plant was operating on fuel oil. Whether run by natural gas or fuel oil, CALPUFF simulation results for both seasons showed that NO_x concentrations were higher when GTs were used in the combined cycle mode. The concentrations were still lower than the allowable concentrations set by the United States Environmental Protection Agency (U.S. EPA) standards. In contrast, for the case where the power plant operated on fuel oil, the NO_x one-hour average simulated results exceeded the allowable limits only when the combined cycle mode was activated.     

桨叶的组合共振理论建模与分析

目的 对直升机单片桨叶在2个激励力下的组合共振进行理论研究。方法 桨叶以固定角速度旋转,视为旋转的细长悬臂梁,受2个不同频率的简谐激励力作用。首先基于哈密顿原理推导旋转梁控制方程,考虑几何大变形和非线性惯性。其次对方程无量纲化,并采用伽辽金法对控制方程进行离散,最后使用摄动法中的L-P法(Lindstedt-Poincare method)对无量纲方程进行求解。结果 获得了组合共振产生条件,同时得到了组合共振下的稳态幅频响应和相应的时间历程图。进一步获得了超谐波/次谐波共振与组合共振同时发生的条件,并对组合共振进行了参数分析,探索了各个激励频率成分、阻尼和激振位置等对组合共振的影响。结论 当2激励力满足2Ω1±Ω2=ω0、2Ω2±Ω1=ω0或1/2(Ω1±Ω2)=ω0其中之一时,旋转梁可能发生组合共振。组合共振响应中,自由振动成分占主导,存在超谐波共振时,组合共振振幅得到进一步增强。     

Nonlinear control of a wind turbine based on nonlinear estimation techniques for maximum power extraction

This work proposes nonlinear estimators with nonlinear controllers, for variable speed wind turbine (VSWT) considering that either the wind speed measurement is not available or not accurate. The main objective of this work is to maximize the energy capture from the wind and minimizes the transient load on the drive train. Controllers are designed to adjust the generated torque for maximum power output. Estimation of effective wind speed is required to achieve the above objectives. In this work the estimation of effective wind speed is done by using the Modified Newton Rapshon (MNR), Neural Network (NN) trained by different training algorithms and nonlinear time series based estimation. Initially the control strategies applied was the classical ATF (Aerodynamic torque feed forward) and ISC (Indirect speed control), however due their weak performance and unmodeled WT disturbances, nonlinear static and dynamic feedback linearization techniques with the above wind speed estimators are proposed.     

Effects of wind‐energy facilities on breeding grassland bird distributions

The contribution of renewable energy to meet worldwide demand continues to grow. Wind energy is one of the fastest growing renewable sectors, but new wind facilities are often placed in prime wildlife habitat. Long‐term studies that incorporate a rigorous statistical design to evaluate the effects of wind facilities on wildlife are rare. We conducted a before‐after‐control‐impact (BACI) assessment to determine if wind facilities placed in native mixed‐grass prairies displaced breeding grassland birds. During 2003–2012, we monitored changes in bird density in 3 study areas in North Dakota and South Dakota (U.S.A.). We examined whether displacement or attraction occurred 1 year after construction (immediate effect) and the average displacement or attraction 2–5 years after construction (delayed effect). We tested for these effects overall and within distance bands of 100, 200, 300, and >300 m from turbines. We observed displacement for 7 of 9 species. One species was unaffected by wind facilities and one species exhibited attraction. Displacement and attraction generally occurred within 100 m and often extended up to 300 m. In a few instances, displacement extended beyond 300 m. Displacement and attraction occurred 1 year after construction and persisted at least 5 years. Our research provides a framework for applying a BACI design to displacement studies and highlights the erroneous conclusions that can be made without the benefit of adopting such a design. More broadly, species‐specific behaviors can be used to inform management decisions about turbine placement and the potential impact to individual species. Additionally, the avoidance distance metrics we estimated can facilitate future development of models evaluating impacts of wind facilities under differing land‐use scenarios.     

Energy conservation and waste utilization in the cement industry serve the green technology and environment

The cement industry is one of the most energy-intensive industries consuming 4 GJ/ton of cement, i.e. 12–15% of the energy use in total industry. Energy cost accounts for 30% of the total cost of cement production. Seventy-five per cent of this energy is due to the thermal energy for clinker production. It is also found that 35% of this supplied thermal energy is lost in flue gas streams. Most modern kilns use pet coke or coal as their primary fuel. Instead, the municipal waste in landfills offer a cheap source of energy and reduce the environmental effects of dumping solid waste. The calcination and drying processes and the kiln need large quantities of thermal energy. About 40% of the total energy input is lost in the hot flue gases and cooling the stack plus the kiln shell. Hence, it is suitable to use an organic Rankine cycle (ORC) to recover the exhaust energy from the kiln. Alternatively, a 15 MW gas turbine engine combined with a steam turbine could be utilized. It was found that ORC produces 5 MW with a capital cost recovery period of 1.26 years. However, the gas turbine combined system produces 21.45 MW with a maximum recovery period of 2.66 years.     

海洋工况下航空发动机冷端叶片的冲蚀损伤与防护概述

围绕海洋环境下航空发动机的服役特点,针对发动机叶片在海洋/近岸地区不同气候条件下的工作状况,对发动机冷端叶片在腐蚀-冲蚀联合作用下的失效机制进行了梳理总结.对海洋环境下服役的发动机叶片防护涂层的相关研究进行了归纳,总结了不同叶片防护涂层的设计理念及其性能表现.对于航空发动机叶片的防护涂层,目前主要是以一元或多元金属氮化物涂层,和金属相与陶瓷相的键合涂层为主,两类涂层的设计目的在于通过控制涂层中的相含量来调控涂层的强韧比和耐磨耐蚀性.     

新型乙醇汽油防静电混合器数值模拟研究

设计了一种新型乙醇汽油防静电混合器,基于CFD方法对新型乙醇汽油防静电混合器及简单的T型管混合器的内部流场分别进行数值分析,通过比较混合器中各组分浓度分布、压力分布、速度分布等特征,研究乙醇与汽油在混合器中的混合效果,并分析静电产生的风险。结果表明：在新型混合器螺旋叶片的作用下,乙醇汽油在出口处几乎混合均匀,速度趋于一致,且压力损失较小,说明新型混合器可以在较小的能耗下获得较好的混合效果,从而有效减少静电积聚。     

Theoretical Calculation and Economic Assessment of the Integrated Solar Combined Cycle Power Plants

The ISCC technology representing an integrated solar combined cycle and the economic assessment of ISCC are investigated. Comparisons conducted by theoretical calculation method among two cases, that is, an integrated solar combined cycle system (ISCCS) and a combined cycle gas turbine system (CCGTS) show that ISCCS provides the best solution with the highest efficiency of heat to electricity among them. The results reflected by theoretical calculation also reveal that ISCCS is beneficial to energy saving and emission reduction. Due to the great advantages of ISCC, comprehensive analysis on the basic conditions for building ISCC power plants is analyzed in detail.     

Sustainable gas turbine power generation by adopting green control technologies

Performance analysis of a gas turbine with two configurations (a parallel and series free turbine) is presented and analysed. A simple configuration is analysed here for comparison. The performance parameters are work output, specific fuel consumption (SFC) and efficiency. Off-design characteristics are based on two methods of control, the first (A) is fixing the compressor–turbine inlet temperature (TIT) and varying the power TIT, whereas the second (B) method is by varying the two turbine-inlet temperatures while keeping them equal. Conclusively the series configuration has higher work output (11%), whereas the parallel arrangement has higher efficiency and lower SFC (9%). Hence, as a compromise, it is more efficient and work-productive to use method A (TIT = const.) to control both series and parallel arrangements than using method B (TIT = T₅).     

避灾硐室气刀型空气幕数值模拟研究

结合避灾硐室阻隔有害气体的需要,对气刀型空气幕进行模拟研究,从气刀的工作原理、风速分布、阻隔效果的角度出发,分别建立物理模型及划分网格,得到了气刀工作时其周围压力的分布变化规律,不同送风方式下气刀风速分布规律以及单侧送风条件下CO,浓度分布规律,证明了气刀具备增大了气流的输出,阻隔有害气体的作用。由风速统计规律得出,气刀在单侧送风15m／s或者双侧送风10m／s条件下,气刀的有效覆盖率大于85％,又根据数值模拟得出,在有效覆盖率大于85％的条件下,CO2阻隔效果明显,有害气体无法通过气刀形成的空气幕。