Land-based Power Plant Research Articles

Fractal Nature of Advanced Ni-Based Superalloys Solidified on Board the International Space Station

Materials science is highly significant in space program investigation, energy production and others. Therefore, designing, improving and predicting advanced material properties is a crucial necessity. The high temperature creep and corrosion resistance of Ni-based superalloys makes them important materials for turbine blades in aircraft engines and land-based power plants. The investment casting process of turbine blades is costly and time consuming, which makes process simulations a necessity. These simulations require fundamental models for the microstructure formation. In this paper, we present advanced analytical techniques in describing the microstructures obtained experimentally and analyzed on different sample’s cross-sectional images. The samples have been processed on board the International Space Station using the MSL-EML device based on electromagnetic levitation principles. We applied several aspects of fractal analysis and obtained important results regarding fractals and Hausdorff dimensions related to the surface and structural characteristics of CMSX-10 samples. Using scanning electron microscopy (SEM), Zeiss LEO 1550, we analyzed the microstructure of samples solidified in space and successfully performed the fractal reconstruction of the sample’s morphology. We extended the fractal analysis on the microscopic images based on samples solidified on earth and established new frontiers on the advanced structures prediction.

Performance analysis of a 10 MWp utility scale grid-connected canal-top photovoltaic power plant under Indian climatic conditions

Photovoltaic modules installed on water bodies save large land areas but climatic conditions for such solar power plants, are different due to their proximity to flowing water.Thus it is important to study the performance of a canal-top solar PV plant for its reliable operation. In the present study, energetic, exergetic performance and reliability analysis of a 10 MWp grid-connected canal-top PV plant, is studied using more than 2 years data. The average monthly performance ratio, system efficiency and exergy efficiency of the plant, are found to be 0.78, 11.90% and 12.03%, respectively. PV degradation rate is found to be higher than land based power plants. The average monthly exergy efficiency, useful thermal exergy convective heat transfer loss and exergy destruction during monitoring period, are found to be 12.03%, 18.32%, 1% and 58.65%, respectively. The performance of present plant is found to be slightly lower than land based PV plants. The possible solutions to improve output power generation by canal-top PV plants are discussed. The water saved due to reduced water evaporation is found to be about 95 million litres per year.Further follow up research areas are identified to enhance the reliability of such power plants installed over water bodies.

Experimental characterizing combustion emissions and thermodynamic properties of a thermoacoustic swirl combustor

Many practical lean-premixed combustion systems involved in land-based power plants, gas turbines and boilers are susceptible to self-excited combustion instability, which is characterized by detrimental periodic pressure oscillations. Little attention has been paid on experimentally characterizing the chemical emissions and thermodynamic properties of a thermoacoustic swirl combustor. In this work, the effects of (1) fuel-air equivalence ratio Φ and fuel flow rate QCH4 on generating such combustion instability and its impact on chemical emissions and thermodynamic properties in a swirling combustor are experimentally studied. For this, a methane-fueled lab-scale swirl combustor is designed and tested. To monitor the thermodynamic properties of the combustor, an acoustic pressure sensor, an infrared thermal imaging camera, K-type thermal couples, and an infrared flue gas analyzer are applied. It is found that the fuel-air ratio plays an important role on generating combustion instability at different frequencies and amplitudes. This is confirmed by conducting autocorrelation and frequency spectrum analyses of the acoustic pressure time trace. Furthermore, the dominant mode swap (mode-switching) between a low frequency ω1 and a high non-harmonic one is experimentally observed. Whether the mode switching from high (harmonic or non-harmonic) to low frequency or low to high frequency is found to depend strongly on QCH4. As the equivalence ratio is changed from lean to rich, i.e. 0.8 ≤ Φ ≤ 1.2, NOx emission is increased from 1 ppm to 37 ppm. However, CO emission is decreased by 2 order of magnitudes from 1000 ppm first and then increased. The minimum CO emission is approximately 3.0 ppm. In addition, O2 concentration is decreased by more than 80% with increased Φ, depending on the methane flow rate. This means that the combustion efficiency characterized by the O2 emission is decreased dramatically from 99.5% to 68% with Φ increased from 0.6 to 1.2. The present work sheds light on the characteristics of chemical emissions and thermodynamic properties, when a thermoacoustic swirl combustor is operated with methane-air equivalence ratio Φ varied from lean to rich condition and different QCH4. It opens up a practical means to design a stably operated but low-emission thermoacoustic swirl combustor.

Liquation Cracking in the Heat-Affected Zone of IN738 Superalloy Weld

The main scope of this study investigated the occurrence of liquation cracking in the heat-affected zone (HAZ) of IN738 superalloy weld, IN738 is widely used in gas turbine blades in land-based power plants. Microstructural examinations showed considerable amounts of γ’ uniformly precipitated in the γ matrix. Electron probe microanalysis (EPMA) maps showed the γ-γ’ colonies were rich in Al and Ti, but lean in other alloy elements. Moreover, the metal carbides (MC), fine borides (M3B2 and M5B3), η-Ni3Ti, σ (Cr-Co) and lamellar Ni7Zr2 intermetallic compounds could be found at the interdendritic boundaries. The fracture morphologies and the corresponding EPMA maps confirmed that the liquation cracking in the HAZ of the IN738 superalloy weld resulted from the presence of complex microconstituents at the interdendritic boundaries.

Dual fuel consumption and efficiency of marine steam generators for the propulsion of LNG carrier

The steam generator is an essential component of marine steam propulsion plant. Nowadays steam propulsion is a relatively rare occurrence, but still dominant in the LNG carriers. LNG carrier analyzed in this study is equipped with two identical, mirror-oriented steam generators. In exploitation, steam generator burners use two types of fuel: heavy fuel oil and natural gas. Measurements were performed for various steam generator operating parameters in ship exploitation at different loads. Data values from conducted measurements were used in the equations for calculating energy and exergy efficiencies and losses of analyzed steam generators at various loads. Also, measured fuel consumption data from exploitation were compared with the manufacturer’s test data. Analyzed steam generator’s energy and exergy efficiencies and losses were compared with the efficiencies and losses of steam generators from land based power plants. As the primary function of the marine steam generators is the production of steam at required pressure and temperature for the main propulsion turbine operation, several operating regimes of the main propulsion turbine, based on the measured data from exploitation, are presented. Finally, the paper presents calculated CO2 emissions for three different steam generator operating modes: from exploitation using both fuels, then when a steam generators use only natural gas and when a steam generators use only heavy fuel oil. The highest cumulative CO2 emissions were obtained at the higher steam generator loads, while at the same loads, specific CO2 emissions per kWh of total produced power on the main turbine are the lowest.

Maritime environmental performance indicators for urban waterways in Amsterdam

Owing to new regulations starting from 2025, all commercial canal boats have to comply to zero local emission standards in Amsterdam. It is therefore vital that a clear emission indicator is made available for vessels with a varying operational profile, such as canal boats. In this paper, it is argued that current indicators, such as the Energy Efficiency Design Index, are not suitable for these (passenger) vessels. This paper proposes environmental performance indicators that can quantify emissions, (non-dimensional) energy and fuel usage based on an operational profile set in the design phase. This profile includes part load operation and auxiliary consumers and it can compare new designed concepts with current baseline vessels based on the ‘benefit for society’ of different vessel types. In the proposed environmental performance indicators, several operational modes can be defined, in contrast with the currently proposed Energy Efficiency Design Index, which is a point index at 75% of installed power. To gauge not only local emissions but also global emissions, the environmental performance indicator methodology is used to determine a minimum efficiency from any power generation method. This minimum efficiency follows from a comparison between baseline vessels and concepts that are more energy efficient and emission friendly. The proposed environmental performance indicators were validated using measurements on typical propulsion configurations of canal boats in Amsterdam. Three full electric concepts were designed and compared with the measured baseline vessels. As full electric concepts do not have local emissions, the method of power generation must satisfy the requirement to have less global emissions than the mechanical baseline. Furthermore, an energy efficiency of at least 33% is calculated from a fossil-fuelled land-based power plant (including transport) to the boundary from quay to boat to be required for newly designed electric concepts to be more energy efficient than the mechanical baseline.

Performance and emission characteristics of additives-enhanced heavy fuel oil in large two-stroke marine diesel engine

The International Maritime Organization (IMO) Marine Environment Protection Committee (MEPC) has gradually strengthened the laws regulating ship exhaust emissions. The majority of ships designed for international voyages and powered by large two-stroke marine diesel engines use heavy fuel oil (HFO), which has the advantage of a low price compared to other types of fuel. However, HFO generates large amounts of harmful exhaust emissions during combustion in a marine diesel engine. In addition, as fuel costs account for a large portion of the expenditure budgets of the shipping companies that operate and manage such ships, fuel cost reduction is of considerable interest to such companies. In this study, two fuel additives, oil-soluble Ca-based and oil-soluble Fe-based organometallic compounds, which can improve the performance of diesel engines, were injected into HFO at fixed concentrations (1/4000 and 1/6000 of the total fuel, respectively), in attempts to reduce fuel consumption and exhaust emissions. For enhanced experimental accuracy and reproducibility, a large two-stroke diesel engine installed in a land-based power plant was used as the test subject. Evaluative tests were conducted for three engine loads (50%, 75%, and 100%). The engine performance (i.e., the fuel consumption rate, maximum combustion pressure, and exhaust gas temperature) and the exhaust emissions (NOx, particulate matter (PM)) were analyzed before and after the fuel additive insertion.

Preparing for the Future: Reducing Gas Turbine Environmental Impact—IGTI Scholar Lecture

In the long term, the price of fuel will rise and it is now urgent to reduce carbon dioxide emissions to avoid catastrophic climate change. This lecture looks at power plant for electricity generation and aircraft propulsion, considering likely limits and possibilities for improvement. There are lessons from land-based gas turbines, which can be applied to aircraft, notably the small increases in efficiency from further increase in pressure ratio and turbine inlet temperature. Land-based gas turbines also point to the benefit of combining the properties of water with those of air to raise efficiency. Whereas the incentive to raise efficiency and reduce CO2 will force an increase in complexity of land-based power plant, the opportunities for this with aircraft are more limited. One of the opportunities with aircraft propulsion is to consider the whole aircraft operation and specification. Currently the specifications for new aircraft of take-off and climb thrust are not fully consistent with designing the engine for minimum fuel consumption and this will be addressed in some depth in the lecture. Preparing for the future entails alerting engineers to important possibilities and limitations associated with gas turbines which will mitigate climate change due to carbon dioxide emissions.

第２世代Ｎｉ基単結晶超合金ＴＭＳ‐８２＋の長時間クリープ特性

Long component-life of at least two years under a daily start and stop condition is required on turbine blades and vanes in land-based power plants. For this reason, a creep rupture life of 10000 hours or longer is required for the application of Ni-base superalloys. In this paper, long-term creep property of more than 15000 hours was analyzed for a second-generation Ni-base superalloy, TMS-82+. Consequently, Larson-Miller parameters in the range of C=12-14 resulted in good fits over the short-to-long-term creep rupture life, even though C=20 is conventionally used for Ni-base superalloys. In addition, the creep strength of TMS-82+ exceeds that of CMSX-4 under wide range of stress/temperature conditions, especially under the higher temperature and lower stress condition.

水溶性液体貨物の海中拡散

The amount of transportation of water-soluble toxic chemicals by ships is very large. It is concerned that an outflow accident of such chemicals might cause the undesirable influence on the ocean environment before the dilution process with sea water will make them harmless.The diffusion process beneath the sea surface of water-soluble chemicals spilt from ships at a collision or stranding is similar to that of hot drain from land based power plants. In case of hot drain, a lot of research have been done and its diffusion process, Which is usually treated as the gravitational plume considring the density difference between hot drain and surrounding sea water, has almost been elucidated.In case of watrer-soluble chemicals, however, the density difference distributes widely depending on the substances and usually differs from that of hot drain. Moreover some chemicals release reaction heats when it defuses in sea water. It has not been confirmed yet that the evaluatoin method based on dimensionless numbers and the empirical correlations proposed in the past reports can be applied to such chemicals.Then to make this problem clear, some experiments using a small-scale tank were conducted. As experimental solutes, three kind of typical chemicals with different properties were selected. Experimental parameters were the outflow rate and the relative velocity between the spilling source and surrounding water. The diffusion characteristics such as the direction and width of the plume were observed and compared with the empirical correlations published so far.As a result, it was found that the diffusion characteristics except one chemical can well be estimated by the method applied to the gravitational plume of hot drain if Froude number is chosen as the controlling dimensionless number, although a different result was anticipated because the transport properties and density of chemicals used in the experiment are very different from those of hot drain.

4508677 Modular nuclear reactor for a land-based power plant and method for the fabrication, installation and operation thereof : Edwin Craig, Be Blumberg assigned to General Electric Company

4508677 Modular nuclear reactor for a land-based power plant and method for the fabrication, installation and operation thereof : Edwin Craig, Be Blumberg assigned to General Electric Company