Energy Generation Plants Research Articles

Applicability of Municipal Solid Waste Incineration Ash on Base Layers of Pavements

AbstractThis study presents the characteristics of municipal solid waste (MSW) incineration ash obtained from an electric energy generation plant and evaluates the MSW ash applicability in base road pavement layers through the mixture of ash with a nonlateritic regional clay soil. Chemical, physical, and mechanical tests and the mechanistic-empirical design for a typical pavement structure were carried out on the pure soil and also in the soil mixture with the addition of different ash content (20 and 40%). Fly ash reduced the expansion of the material, showing an increase in the California bearing ratio (CBR) and resilient modulus value. The results are satisfactory, depending on the content and type of ash used, highlighting the positive work of MSW fly ash for its use in base road pavement layers.

Modeling and Simulation of Wave Energy Generation Plants: Output Power Control

The control and simulation of the power delivered to the grid are becoming an important topic, particularly when the number of distributed power generation systems increases. In this paper, two different control schemes for an oscillating-water-column Wells-turbine-generator module are simulated, implemented, and compared. In the first method, the control system does appropriately adapt the slip of the induction generator according to the pressure drop entry in order to maximize the generated power, while in the second method, a traditional proportional-integral-derivative-based control is implemented in order to deal with the desired power-reference-tracking problem. It will be shown how the controllers avoid the stalling behavior and that the average power of the generator fed into the grid is significantly higher in the controlled cases than in the uncontrolled one while providing the desired output power.

Characterization of Irradiation Damage of Ferritic ODS Alloys with Advanced Micro-Sample Methods

Oxide dispersion strengthened (ODS) steels are candidate materials for advanced electric energy and heat generation plants (nuclear, fossil). Understanding the degradation of mechanical properties of these alloys as a result of service exposure is necessary for safe design. For advanced nuclear applications combinations of temperature, irradiation and stress are important damage conditions. They are studied either with neutron irradiated samples (often highly active) or with ion-irradiated samples (irradiation damage often limited to only a few micrometer deep areas). High activity of samples and limited sample volume claim to subsized samples like nano-indentation, micro-pillar compression or thin strip creep testing. Irradiation hardening and irradiation creep were studied with these methods. Ferritic ODS steels with 19% chromium were investigated. The materials were studied in qualities differing in grain sizes and in sizes of the dispersoids. Irradiation was performed in an accelerator using He-ions. Irradiation damage profiles could be well analyzed with indentation. Yield stress determined with compression tests of single-crystal micropillars was well comparable with tension tests performed along the same crystallographic orientation. Irradiation creep of samples with different sizes of dispersoids revealed only a small influence of particle size being is in contrast with thermal creep but consistent with expectations from other investigations.

Feature tests on welded components at higher temperatures—Material performance and residual stress evaluation

A reliable maintenance and service of energy generation plants would be impossible without the professional designing, manufacturing and monitoring of welded joints. The lifetime assessment factors of welded components as implemented in the design codes must be updated accounting for the modern materials and the advanced steam parameters used in the piping construction [Weld Strength for high temperature components design and operation (WELDON). European Project No. GRD2-2000-30363, Gampe U, Seliger P, Creep crack growth testing of P91 and P22 pipe bends. Int J Pressure Vessels Piping 2001;78:859–64, INTEGRITY of repair welds in high temperature plants operating under steady and cyclic loading conditions. European Project No. G5RD-CT-1999-00118]. Within the EU 5th Framework RTD project ‘WELDON’ tests at high temperatures are performed on component-like feature test specimens like welded pipes and large tensiles in addition to laboratory specimens to study the geometry and size effects on the damage evaluation methodology. The circumferential welds of the pipes are subjected simultaneously to internal pressure and an axial load. The large tensile specimens manufactured from the welded pipes are subjected to uniaxial loading. These components are made from steel grade P22 and P91 and are equipped with gages for on-line monitoring of temperatures, deformations and strains. Residual stresses are measured on these components in as welded and after post-weld heat treatment (PWHT) conditions and are monitored during creep testing with interruptions and after failure. X-ray and hole drilling techniques are employed in these measurements. These data will be used to validate the FE modelling of residual stresses and damage assessment. The results obtained from long time creep tests, metallographic investigations of damage development in the different zones of the weldment and residual stress measurements are presented in this paper.

An Analogy on Assessment of Urban Air Pollution in Turkey Over the Turn of the Millennium (1992–2001)

Rapid industrialization and urbanization in Turkey, especially over the last twenty five years, has provided better living standards to its residents, but it also caused a decrease in environmental quality. In late 1970's, air quality monitoring activities were started in some major cities by individual researchers in Turkey. It was just around the 1990's that a countrywide program on continuous air pollution monitoring in major province centers and selected large towns was launched. The impact of air pollution on people depend on various factors, such as existence and magnitude of coal powered energy generation plants, type of urban heating and their efficiency, and the numbers and specifications of vehicles. In this study, current Turkish urban air quality over the turn of the Millennium (1992-2001) is studied in the light of the country's worst cities in terms of outdoor air quality, the number of upper respiratory diseases, sinusitis, bronchitis, and pneumonia cases in these provinces reported by the state medical treatment facilities in 2001. The population that is under outdoor urban air pollution hazard was computed. A comparative analysis between the provinces that use natural gas and others that use fossil fuels was also completed in order to project monetary gains if the studied provinces will transform their indoor heating and industrial operations to be run by natural gas or other cleaner energy sources. If natural gas use in air polluted urban centers could be realized in the near future, approximately 212 to 350 million US dollars per annum could to be saved just by reducing health related problems caused by outdoor air pollution.

Inhomogeneous nano-mechanical properties in the multi-phase microstructure of long-term aged type 316 stainless steel

Microstructure-related local deformation behavior was evaluated using nanoindentation techniques for a type 316 austenitic stainless steel used in energy generation plants. The sample was aged for 39,332 h (4.5 years) at 700 °C. The microstructure included the σ phase precipitated at grain boundaries and in grain interiors. The nanohardnesses of the σ phase and the matrix in the aged and virgin samples were evaluated quantitatively. The hardness of the σ phase was found to be extremely high in the order of 17 GPa, which is much higher than the value of about 3.4 GPa for the matrix in the aged sample. The hardnesses of the σ phase at the grain boundary and the adjoining matrix were the same as those in the grain interior. Moreover, the hardness of the matrix of the aged sample was about 30% lower than that of the virgin sample while the Vickers hardness as a macroscopic strength of the aged sample was about 45% higher than that of the virgin one. The deformation and fracture behavior in a local region was discussed in terms of the inhomogeneous mechanical properties in the multi-phase microstructure.

Mechanical and microstructural properties of HVOF sprayed WC–Co and Cr 3C 2–NiCr coatings on the boiler tube steels using LPG as the fuel gas

The characteristics and the phase composition of high velocity oxy fuel (HVOF) sprayed WC–Co and Cr 3C 2–NiCr coatings applied onto boiler tube steel substrates using liquid petroleum gas (LPG) as the fuel gas, have been evaluated. The coatings were examined using metallography, SEM/EDAX and XRD techniques. An attempt has been made to describe the transformations that take place during HVOF spraying. The purpose of this study was to compare the microstructure, porosity, surface roughness and microhardness of HVOF sprayed WC–Co, Cr 3C 2–NiCr coatings deposited on boiler steels. The paper will also investigate if there is an application of the deposit in energy generation plants with a view to enhance the life of the component and reduce tube failures in such power plants.

The sustainable management of renewable energy sources installations: legal aspects of their environmental impact in small Greek islands

Nowadays, an attractive legislative and financing framework has been established in Greece for the development of renewable energy sources. This has resulted in a strong increase of investors’ interest, especially in the islands, mainly due to their high renewable energy potential all year round. However, the typical characteristics of the small Greek island, which constitute sensitive ecosystems with unique attributes of a natural and cultural heritage, impose a limitation on the development of energy generation plants using renewables. In order to adopt the principles of sustainable development of these island regions, the application of the proportionality principle in relation to other general principles of environmental law is proposed as a suitable legislative tool for resolution of the foreseeable conflicts.