Energy and exergy analysis of a 747-MW combined cycle power plant Guddu

ABSTRACT

The paper presents a detailed study based on the energy and exergy analysis of a combined cycle power plant (CCPP) Guddu having triple pressure heat recovery steam generator (HRSG). The energy loss and the energy efficiency of each plant component with HRSG as a whole is calculated. The exergy destruction of these components and the sub-parts of the HRSG are also found out. All the three stages of the steam turbine are analysed individually. The combustion chamber is found to have the maximum share of exergy destruction while the condenser is having a maximum of energy loss. The total net power output, energy and exergy efficiency of the whole plant is calculated as 737.8?MW, 59.12% and 58.24%, respectively. The error in getting the designed power output of 747?MW is 3.16%. The thermal efficiency of the Brayton and Rankine cycle is 62.01% and 56.38%, respectively.     

Exergy and exergoeconomic analysis of a municipal waste-to-energy steam reheat power plant for Port Harcourt city

This paper presents the exergy and exergoeconomic analysis of a proposed steam reheat power plant powered by the municipal waste of Port Harcourt city in Nigeria, latitude 4°45′ N and longitude 7°00′ E. The projected municipal waste generation of the city for the year 2020 was employed for this work to ascertain the amount of power obtainable via a waste incineration plant, taking into consideration the cost effectiveness of the plant. The thermodynamic analysis of the plant showed that 117?MW could be generated from the projected waste, with plant's first and second law efficiencies of 36.91% and 31.36%, respectively. The plant equipment cost was calculated to be US$326,460,000 with a payback period of about six years. The exergy and exergoeconomic analysis was used to estimate the plant’s unit cost of electricity and evaluate the exergy destruction and cost rates, with respect to the prevalent ambient temperature.     

Thermodynamic analysis of steam-injected gas turbine cycle power plant with inlet air cooling

Steam-injected gas turbine cycle is the modified arrangement of simple gas turbine (GT) cycle, wherein part of steam generated in a heat recovery steam generator is injected into the combustion chamber to increase power output and the efficiency. This paper studies the effect of integration of inlet air cooling, steam injection (SI) and film cooling (FC) on the performance of GT cycle. Two different methods for cooling the inlet air, namely inlet fogging and evaporative cooling, are considered for analysis here. Results show that the inlet fogging is better than evaporative cooling to achieve the lowest temperature at the compressor inlet. Thermodynamic performance of simple GT cycle is also compared with SI in GT cycle. The present study shows that GT cycle with integration of inlet fogging, SI and FC is a better configuration for achieving higher performance.     

Energetic and exergetic performance investigation of the Bigadic Geothermal District Heating System in Turkey

In this study a comprehensive performance analysis of the Bigadic Geothermal District Heating System (GDHS) in Balikesir, Turkey is performed through thermodynamic assessment in terms of energy and exergy efficiencies. The actual thermal data taken from the Technical Department of the GDHS are utilized in the analysis to determine the exergy destructions in each component of the system and the overall energy and exergy efficiencies of the system for two reference temperatures taken as 15.6 °C for November (e.g., case 1) and 11 °C for December (e.g., case 2). The energy and exergy flow diagrams are clearly drawn to illustrate how much destructions/losses take place in addition to the inputs and outputs. The average energy and exergy efficiencies are found to be 30% and 36% for case 1, and 40% and 49% for case 2, respectively. The key reason as to why the exergy efficiencies are higher is because the heat recovery option is used through the reinjection processes which make use of waste heat. A parametric study is also conducted to show how energy and exergy flows change with the environment temperature. The results are expected to be helpful to researchers and engineers in the area.     

Research on performance of high-strength bolted connection in fire and after fire

Experiments on the tensile performance and the shear performance in high temperature and shear performance after fire have been carried out to study the fire-resistant performance of high-strength bolted connection. The experimental research on the shear performance of the connection in high temperature reveals the effect of temperature on the mechanical performance of high-strength bolted steel. A formula for the mechanical performance index can be obtained through a comparative analysis. The research on the shear performance of high-strength bolt in high temperature presents the effect of temperature on the bolt's sliding load and limit load. The formula for calculating the sliding load and limit load for shear connection at high temperature can be put forward through a comparative analysis on the basis of the test results. The test results for the shear property of post-firing high-strength bolted connection reveal the change law of the sliding load in different fire temperatures, fire processing methods and types of cooling. Moreover, the calculation formula of the reduction coefficient of the sliding load is given. Research findings provide theoretical basis for research on fire-resistant performance of steel structure joints and the prerequisite for overall fire-resistant design of steel structures and act as an important reference for compiling and revising relevant codes. This paper can promote the improvement and development of fire-resistant design methods of steel structures.     

A study on estimating the energetic and exergetic prices of various residential energy sources

In choosing the type of any energy sources for residential and other uses, their prices play in general a big role. These prices are based on energy values. Besides this, the application of the exergy, which is a way to a sustainable future, is more meaningful in providing information for long-term planning of resource management. In the present study, energy and exergy prices of various energy sources are investigated. The energy sources considered include coal, natural gas, furnace oil, diesel oil, liquefied petroleum gas (LPG) and wood, while electric resistance along with heat pump and district heating are also covered. In this context, chemical exergy relations of these energy sources are presented first. The prices of various energy sources in the Turkish residential sector, which is given as an illustrative example, are then used in the calculations. Finally, the energy and exergy prices are compared with each other, while the main conclusions are listed. The highest unit energy price is that of diesel oil, while the lowest one is that of natural gas. The differences between the energy and exergy prices are small for all energy carriers.     

Energetic and exergetic analysis and assessment of a thermal energy storage (TES) unit for building applications

The main objective of this study is to investigate the energetic and exergetic performances of a latent energy storage system in both charging (solidification) and discharging (melting) processes. A shell-and-tube TES unit was designed, constructed and tested in Dokuz Eylul University, Izmir, Turkey. This experimental unit basically consisted of a heat exchanger section, a measurement system and flow control systems. For the charging mode, the inlet temperatures varied to be −5 °C, −10 °C and −15 °C, while the volumetric flow rates changed to be 2 l/min, 4 l/min and 8 l/min. The experiments were performed for three different tube materials, copper, steel and PE32 and two various shell diameters of 114 mm and 190 mm to investigate the tube material and shell diameter effects on energetic and exergetic efficiencies. It may be concluded that for the charging period, the exergetic efficiency increased with the increase in the inlet temperature and flow rate. For discharging period, irreversibility increased as the temperature difference between the melting temperature of the PCM and the inlet temperature of the heat transfer fluid (HTF) increased and hence the exergy efficiency increased.     

U形毛细管席冷却顶板换热性能数值模拟与分析

通过建立毛细管席的三维流-固耦合换热模型,应用CFD软件进行数值计算,分析各因素对供冷能力的影响和毛细管内水温变化规律,为毛细管席产品优化和设计参数的确定提供参考。     

火力发电厂空调冷却水系统分析

通过对8个火力发电厂进行调研，收集了有关集控室空调冷却水的设计方案、水质资料及运行情况，分析结果表明，火力发电厂空调冷却水系统均满足生产及工艺要求。     

Building typologies as a tool for assessing the energy performance of residential buildings - A case study for the Hellenic building stock

Successful strategies towards minimizing the energy consumption and greenhouse gas emissions attributed to the building sector require knowledge on the energy-related characteristics of the existing building stock. Despite the numerous studies on energy conservation applications in buildings, current knowledge on the energy-related characteristics of the building stock still remains limited. Building typologies can be a useful instrument to facilitate the energy performance assessment of a building stock. This work is based on a harmonised structure for European building typologies (TABULA) developed for residential buildings, but the methodology may be extended to the tertiary sector as well. National typologies are sets of model buildings with characteristic energy-related properties representative of a country's building stock. The model buildings are used as a showcase for demonstrating the energy performance and the potential energy savings from typical and advanced energy conservation measures (ECMs) on the thermal envelope and the heat supply system. The proposed Hellenic residential building typology is presented for the first time along with an assessment of various ECMs that are used for an estimate of the energy performance of building stock in Greece in an effort to meet the 9% indicative national energy savings target by 2016.     

火力发电厂汽机辅机的优化运行探讨

介绍了火力发电厂汽机辅机的组成,分析了汽机辅机系统在运行过程中存在的问题,针对该问题提出了优化运行的措施,以提高辅机的运行效率,推动我国电力工业的快速发展。     

Sludge dewatering in a conventional plant with phosphorus removal-II: Study on centrifuge and filter-press performance

Dewatering tests were carried out at the Cesenatico sewage treatment plant to point out the influence of phosphorus removal on sludge characteristics, using either aluminium or ferrous sulphate. Equipment performance was studied in different conditions to determine the influence of machine operational variables.As far as centrifugation is concerned, the results showed that the most significant variables the dewatered sludge concentration depends on are the beach residence time and liquid ring height. The feed sludge concentration proved a significant variable if all the data obtained in the three phases are considered together. A pressure filtration model for the prediction of final cake concentration was set up based on the correlations of coefficients a and b of the filtrate flow curve (φ = a·t^b) with sludge characteristics (concentration, specific resistance to filtration) and with maximum operating pressure.     

某核电站安全壳锚固区性能优化研究

针对核电站安全壳锚固体系的结构安全性,利用有限元分析软件ANSYS对OVM15R-37C型锚垫板与优化后OVM15R-37CP型锚垫板进行受力分析对比,结果表明,优化后的锚垫板不仅性能更好,而且较前者也更为经济。结合OVM15R-37CP型锚垫板荷载传递实验结论和锚固区混凝土应力分布规律,验证结构的安全性以及有限元模拟的合理性。     

Effects of roof tile permeability on the thermal performance of ventilated roofs: Analysis of annual performance

This paper shows the results of the second part of an experimental study aimed at analysing the effects of roof tile permeability on the thermal performances of ventilation ducts. Ventilation ducts under the layer of tiles are typically used in south European countries to limit the energy load during the summer period. The results of the first part of the study, carried out by analysing 14 different types of roof, proved that the air permeability of the layer of tiles determines a certain amount of heat to be released, in addition to the release connected with the stack effect, in ventilation ducts which have the same characteristics but are perfectly airtight. However, the study did not completely resolve some issues since it was carried out on a model roof (6 m × 1.5 m) with devices to raise the layer of tiles and to create the ventilation duct but without those building elements which are present in real roofs and are used to stop insects and small animals from entering the ventilation duct. These elements narrow the inlet and outlet and consequently cause important reductions in pressure. Moreover, the measurements were based on data collected for limited periods of time during the summer season.     

1GW 汽轮机主、再热汽管道疏水系统优化设计

介绍了广东平海电厂2×1GW主蒸汽、再热蒸汽管道疏水系统的优化设计     

正交胶合木-混凝土螺栓连接力学性能试验研究及参数分析

为研究正交胶合木(CLT)-混凝土螺栓连接的力学性能,对12个顺纹连接试件和12个横纹连接试件进行了单调加载和低周往复加载试验,总结了连接典型的破坏模式,得到了连接的初始刚度、承载力及延性系数等力学性能;利用ABAQUS软件对连接进行非线性参数分析,研究螺栓直径、螺栓强度等级及CLT层板厚度等参数对连接力学性能的影响。结果表明：连接的破坏模式与厚径比(CLT厚度与螺栓直径之比)相关,当厚径比不大于6.56时,主要发生单塑性铰屈服、木材销槽承压及局部承压破坏;螺栓直径一定时,增加CLT层板厚度可有效提高连接承载力;当厚径比大于6.56时,主要发生螺栓双塑性铰屈服与剪断破坏;增加层板厚度对连接初始刚度、承载力和破坏模式无明显影响。针对螺栓屈服破坏模式,增大螺栓直径可提高连接的初始刚度与承载力;提高螺栓强度等级对初始刚度影响较小,但可提高连接承载力。     

环境因素与疲劳荷载耦合作用下预应力混凝土结构性能研究现状与展望

预应力混凝土结构广泛地应用于桥梁工程中。随着车辆通行量的日益增加、环境的逐渐恶化,预应力混凝土桥梁服役性能日渐劣化。对环境因素与荷载(尤其疲劳荷载)作用下预应力混凝土桥梁结构服役性能的研究成为热点。从材料、结构构件、研究方法等方面介绍了环境与荷载共同作用下预应力混凝土桥梁结构服役性能以及研究方法、寿命预测方法的研究现状以及存在的问题。在此基础上,探讨了环境与荷载耦合作用下预应力混凝土桥梁结构服役性能研究的发展方向。     

The effects of roof reflectance on air temperatures surrounding a rooftop condensing unit

Recent anecdotal information suggests that “cool” roofs might produce significant energy savings by reducing the temperature of air entering rooftop air-conditioner (RTU) condensers. Unfortunately, measurements to support this claim are not well documented. To overcome this problem, we carried out a set of six rigorous field experiments to determine the effects of roof reflectance on the heating of condenser inlet air by the roof, and to assess the effects of condenser fan operation on the potential recirculation of hot discharge air from the condenser. The experiments involved combinations of two roof conditions (a “hot” roof and then the same roof with a “cool” coating) and three RTU operation modes (condenser fan and compressor both operating, condenser fan operating without the compressor, and condenser fan and compressor both not operating). For each case, we continuously measured outdoor air temperature at 26 locations near and far from the RTU, as well as roof surface temperatures at 2 locations (1 near and 1 far from the RTU), wind speed and direction, and solar radiation.     

某超长混凝土结构温差效应分析及构造措施

杭州某项目地下室为双向超长结构,上部主楼为单向超长结构,温差收缩效应显著,一般构造措施难以满足要求。采用有限元方法对结构的温差收缩效应进行详细的分析,得到温度应力分布的规律及数值。在分析结果的基础上,对不同部位采取不同的对应措施,有效地解决了温差收缩效应带来的不利影响,对超大、超长混凝土结构设计有一定的参考价值。