Power Plant

Hydrogen and oxygen generation due to the radiolysis of water is a recognized hazard in pipe systems used in the nuclear industry, where the accumulation of hydrogen and oxygen at high points in the pipe system is expected, and explosive conditions exist. Pipe ruptures at nuclear facilities were attributed to hydrogen explosions inside pipelines, in nuclear facilities, i.e., Hamaoka, Nuclear Power Station in Japan, and Brunsbuettel in Germany. Prior to these accidents an ignition source for hydrogen was questionable, but these accidents, demonstrated that a mechanism was, in fact, available to initiate combustion and explosion. Hydrogen explosions may occur simultaneously with water hammer accidents in nuclear facilities, and a theoretical mechanism to relate water hammer to hydrogen deflagrations and explosions is presented herein.

Use of solar energy is of great importance in reducing greenhouse gases emission. Although there are some advances in solo solar power systems, the efficiencies and costs of these systems are not so attractive. This paper presents a new approach for solar power utilization, i.e. using solar heat to replace the extracted steam to heat the feedwater in the regenerative Rankine plant. The exergy merit index EMI (the ratio of the work generated by the saved steam to the exergy supplied by the solar heat) of such solar-aided systems can be greater than 100% while the maximum exergy efficiencies of the solo solar power systems can never reach 100%. The analysis of a three-stage regenerative Rankine plant shows that, by using solar energy, the work generated can be increased up to 30% while the EMI reaches 101.28%. Therefore low-grade heat and other waste heat can be utilized as a valuable source of work in this way. The “aided” concept has special meaning for solar power utilization. In summer, both the solar radiation and the electrical load demand reach their peaks. The increased solar radiation can generate increased power to meet the increased power demand. In addition, the solar aided system can also eliminate the variability in power output in solo solar power systems.

The PyRos technology is a new flash pyrolysis technology that is able to produce a solids-free high-quality bio-oil from wood (saw dust) and biomass residues (jatropha cake, coconut residue, sunflower residue, etc). In this patented technology the reactor and the oil vapour cleaning unit are integrated in one cyclonic reactor with a rotating particle separator. Advantages of the PyRos technology are: a compact system, solids-free oil, less contaminants in the oil, lower viscosity, and lower costs. Flash pyrolysis is a thermal conversion process to produce oil from organic feeds (e.g biomass, waste residues, etc). About 45-70% of the (dry) feed can be converted into oil. The process takes place in a few seconds at about 500 °C and atmospheric pressure. The thus produced oil can be used either for power generation or it can be upgraded to a high-quality product for the chemical industry. The PyRos flash pyrolysis technology is a low-cost compact technology that can be used on both sma...

In the European FP6 research project CACHET palladium-based hydrogen membrane reactors for pre-combustion CO2 capture from natural gas combined cycles are being developed. In the project both the electroless plating method used by DICP and the SINTEF two-stage membrane preparation method based on magnetron sputtering have been successfully up-scaled to produce membranes with a length of 50 cm. The membranes

A series of experiments was conducted to study the effect of twisted-tape width on the heat transfer and pressure drop with laminar flow in tubes. Data for three twisted-tape wavelengths, each with five different widths, have been collected with constant wall temperature boundary condition. Correlations for the friction factor and Nusselt number are also available. The correlations predict the experimental data to within 10 to 15 percent for the heat transfer and friction factor, respectively. The presence of the twisted tape has caused the friction factor to increase by a factor of 3 to 7 depending on Reynolds number and the twisted-tape geometry. Heat transfer results have shown an increase of 1.5 to 3 times that of plain tubes depending on the flow conditions and the twisted-tape geometry. The width shows no effect on friction factor and heat transfer in the low range of Reynolds number but has a more pronounced effect on heat transfer at the higher range of Reynolds number. It i...

SUMMARY Nowadays, the installed power capacity of Itaipu Power Plant is 14.000 MW, with a energy production around 90.000 GWh per year. This amount of energy makes the plant responsible for the supplying about 23% of Brazil and 90% of Paraguay electricity markets. Another parameter gives an idea of the dimension of the involved systems: only 6% of the energy

... countries since many years ago and it is considered as one of the development indexes [1]. TheBOT contract is a contract in which the client, which usually is from government sector, assigns a private firm with the credit of executing a project or plan within a certain time. ...

Past research with high temperature molten carbonate electrochemical cells has shown that carbon dioxide can be separated from flue gas streams produced by pulverized coal combustion for power generation. However, the presence of trace contaminants, i.e., sulfur dioxide and nitric oxides, will impact the electrolyte within the cell. If a lower temperature cell could be devised that would utilize the benefits of commercially-available, upstream desulfurization and denitrification in the power plant, then this CO2 separation technique can approach more viability in the carbon sequestration area. Recent work has led to the assembly and successful operation of a low temperature electrochemical cell. In the proof-of-concept testing with this cell, an anion exchange membrane was sandwiched between gas-diffusion electrodes consisting of nickel-based anode electrocatalysts on carbon paper. When a potential was applied across the cell and a mixture of oxygen and carbon dioxide was flowed over the wetted electrolyte on the cathode side, a stream of CO2 to O2 was produced on the anode side, suggesting that carbonate/bicarbonate ions are the CO2 carrier in the membrane. Since a mixture of CO2 and O2 is produced, the possibility exists to use this stream in oxy-firing of additional fuel.From this research, a novel concept for efficiently producing a carbon dioxide rich effluent from combustion of a fossil fuel was proposed. Carbon dioxide and oxygen are captured from the flue gas of a fossil-fuel combustor by one or more electrochemical cells or cell stacks. The separated stream is then transferred to an oxy-fired combustor which uses the gas stream for ancillary combustion, ultimately resulting in an effluent rich in carbon dioxide. A portion of the resulting flow produced by the oxy-fired combustor may be continuously recycled back into the oxy-fired combustor for temperature control and an optimal carbon dioxide rich effluent.

The design and performance of the Ghazlan power plant (Kingdom of Saudi Arabia) are described. The study is based on first-and second-law analyses. A full exergy analysis is carried out to identify the potential for improving the plant efficiency. The exergy analysis shows a ...