Showing papers on "Thermal power station published in 2011"

Energy and exergy analyses of thermal power plants: A review

Abstract: The energy supply to demand narrowing down day by day around the world, the growing demand of power has made the power plants of scientific interest, but most of the power plants are designed by the energetic performance criteria based on first law of thermodynamics only. The real useful energy loss cannot be justified by the fist law of thermodynamics, because it does not differentiate between the quality and quantity of energy. The present study deals with the comparison of energy and exergy analyses of thermal power plants stimulated by coal and gas. This article provides a detailed review of different studies on thermal power plants over the years. This review would also throw light on the scope for further research and recommendations for improvement in the existing thermal power plants.

Water use at pulverized coal power plants with postcombustion carbon capture and storage

Abstract: Coal-fired power plants account for nearly 50% of U.S. electricity supply and about a third of U.S. emissions of CO(2), the major greenhouse gas (GHG) associated with global climate change. Thermal power plants also account for 39% of all freshwater withdrawals in the U.S. To reduce GHG emissions from coal-fired plants, postcombustion carbon capture and storage (CCS) systems are receiving considerable attention. Current commercial amine-based capture systems require water for cooling and other operations that add to power plant water requirements. This paper characterizes and quantifies water use at coal-burning power plants with and without CCS and investigates key parameters that influence water consumption. Analytical models are presented to quantify water use for major unit operations. Case study results show that, for power plants with conventional wet cooling towers, approximately 80% of total plant water withdrawals and 86% of plant water consumption is for cooling. The addition of an amine-based CCS system would approximately double the consumptive water use of the plant. Replacing wet towers with air-cooled condensers for dry cooling would reduce plant water use by about 80% (without CCS) to about 40% (with CCS). However, the cooling system capital cost would approximately triple, although costs are highly dependent on site-specific characteristics. The potential for water use reductions with CCS is explored via sensitivity analyses of plant efficiency and other key design parameters that affect water resource management for the electric power industry.

The Impact of Climate Change on Nuclear Power Supply

Abstract: A warmer climate may result in lower thermal efficiency and reduced load-including shutdowns-in thermal power plants. Focusing on nuclear power plants, we use different European datasets and econometric strategies to identify these two supply-side effects. We find that a rise in temperature of 1°C reduces the supply of nuclear power by about 0.5% through its effect on thermal efficiency; during droughts and heat waves, the production loss may exceed 2.0% per degree Celsius because power plant cooling systems are constrained by physical laws, regulations and access to cooling water. As climate changes, one must consider measures to protect against and/or to adapt to these impacts.

Recycled Material for Sensible Heat Based Thermal Energy Storage to be Used in Concentrated Solar Thermal Power Plants

Abstract: Current technologies of concentrated solar power plants (CSP) are under extensive industrial development but still suffer from lack of adapted thermal energy storage (TES) materials and systems. In the case of extended storage (some hours), thousands of tonnes of materials are concerned leading to high investment cost, high energy and GHG contents and major conflicts of use. In this paper, recycled industrial ceramics made by vitrification of asbestos containing wastes (ACW) are studied as candidates to be used as sensible TES material. The material presents no hazard, no environmental impact, good thermophysical properties (λ= 1.4 W m -1 K -1 ; Cp = 1025 J kg -1 K -1 ; p= 3100 kg m -3 ) and at very low investment cost. Thanks to the vitrification process of the wastes, the obtained ceramics is very stable up to 1200 °C and can be directly manufactured with the desired shape. The vitrified ACW can be used as TES material for all kinds of the CSP processes (from medium up to high concentration levels) with properties in the same range than other available materials but with lower cost and without conflict of use. The proposed approach leads also to sustainable TES allowing a pay back of the energy needed for the initial waste treatment. Furthermore, this new use of the matter can enhance the waste treatment industry instead of land fill disposal.

Evaluation of solar aided thermal power generation with various power plants

Abstract: Solar aided power generation (SAPG) is an efficient way to make use of low or medium temperature solar heat for power generation purposes. The so-called SAPG is actually ‘piggy back’ solar energy on the conventional fuel fired power plant. Therefore, its solar-to-electricity efficiency depends on the power plant it is associated with. In the paper, the developed SAPG model has been used to study the energy and economic benefits of the SAPG with 200 and 300 MW typical, 600 MW subcritical, 600 MW supercritical, and 600 and 1000 MW ultra-supercritical fuel power units separately. The solar heat in the temperature range from 260 to 90°C is integrated with above-mentioned power units to replace the extraction steam (to preheat the feedwater) in power boosting and fuel-saving operating modes. The results indicate that the benefits of SAPG are different for different steam extracted positions and different power plants. Generally, the larger the power plant, the higher the solar benefit if the same level solar is integrated. Copyright © 2010 John Wiley & Sons, Ltd.

Fly ash from thermal power plants - waste management and overview

Abstract: COAL-based thermal power plants have been a major source of power generation in India, where 75% of the total power obtained is from coal-based thermal power plants. The coal reserve of India is about 200 billion tonnes (bt) and its annual production reaches 250 million tonnes (mt) approximately. About 70% of this is used in the power sector. In India, unlike in most of the developed countries, ash content in the coal used for power generation is 30–40%. High ash coal means more wear and tear of the plant and machinery, low thermal efficiency of the boiler, slogging, choking and scaling of the furnace and most serious of them all, generation of a large amount of fly ash. India ranks fourth in the world in the production of coal ash as by-product waste after USSR, USA and China, in that order. Fly ash is defined in Cement and Concrete Terminology (ACI Committee 116) as the ‘finely divided residue resulting from the combustion of ground or powdered coal, which is transported from the fire box through the boiler by flue gases’. Fly ash is fine glass powder, the particles of which are generally spherical in shape and range in size from 0.5 to 100 μm. Fly ash is classified into two types according to the type of coal used. Anthracite and bituminous coal produces fly ash classified as class F. Class C fly ash is produced by burning lignite or sub-bituminous coal. Class C fly ash has self-cementing properties. The estimated thermal power generation, coal consumption and ash generation in India is given in Tables 1 and 2.

Water Vapor and Mechanical Work: A Comparison of Carnot and Steam Cycles

Abstract: The impact of water vapor on the production of kinetic energy in the atmosphere is discussed here by comparing two idealized heat engines: the Carnot cycle and the steam cycle. A steam cycle transports water from a warm moist source to a colder dryer sink. It acts as a heat engine in which the energy source is the latent heat of evaporation. It is shown here that the amount of work produced by a steam cycle depends on relative humidity and is always less than that produced by the corresponding Carnot cycle. The Carnot and steam cycles can be combined into a mixed cycle that is forced by both sensible and latent heating at the warm source. The work performed depends on four parameters: the total energy transport; the temperature difference between the energy source and sink; the Bowen ratio, which measures the partitioning between the sensible and latent heat transports; and the relative humidity of the atmosphere. The role of relative humidity on the work produced by a steam cycle is discussed in...

Tower type solar heat power generation system with double-stage thermal storage

Abstract: The invention relates to the technical field of solar energy thermal power generation and discloses a tower-typed solar energy thermal power generation system with two-stage thermal storage. The system at least comprises a photo-thermal conversion subsystem, a two-stage thermal storage subsystem and a power subsystem; wherein, the photo-thermal conversion subsystem is used for receiving and converging solar radiation energy, converting the received solar radiation energy into heat energy, and transmitting the heat energy to the power subsystem or the two-stage thermal storage subsystem; the two-stage thermal storage subsystem is used for storing the heat energy input by the photo-thermal conversion subsystem and providing the heat energy for the power subsystem when the solar radiation energy is not enough; the power subsystem is used for converting the received heat energy into electrical energy and outputting the electrical energy. By adopting the invention, the problem that the steam is difficult to store is solved, and the difficulty that the running of a steam turbine in the previous tower-typed solar energy thermal power generation proposal by taking the steam as heat absorption working substance is influenced by the unstable and discontinuous solar radiation is overcome.