[en] Processes and technologies to produce hydrogen synergistically by the steam reforming reaction using fossil fuels and nuclear heat are reviewed. Formulas of chemical reactions, required heats for reactions, saving of fuel consumption or reduction of carbon dioxide emission, possible processes and other prospects are examined for such fossil fuels as natural gas, petroleum and coal. The 'membrane reformer' steam reforming with recirculation of reaction products in a closed loop configuration is considered to be the most advantageous among various synergistic hydrogen production methods. Typical merits of this method are: nuclear heat supply at medium temperature below 600 deg. C, compact plant size and membrane area for hydrogen production, efficient conversion of feed fuel, appreciable reduction of carbon dioxide emission, high purity hydrogen without any additional process, and ease of separating carbon dioxide for future sequestration requirements. With all these benefits, the synergistic production of hydrogen by membrane reformer using fossil fuels and nuclear energy can be an effective solution in this century for the world which has to use. fossil fuels any way to some extent while reducing carbon dioxide emission. For both the fossil fuels industry and the nuclear industry, which are under constraint of resource, environment and economy, this production method will be a viable symbiosis strategy for the coming hydrogen economy era. (author)

[en] Heat recovery steam generators (HRSGs) are responsible for more and more of the steam generating capacity of many utilities. Unfortunately, they are also increasingly responsible for the number of tube failures in the system. Corrosion that leads to failures often begins before commissioning and is exacerbated by cycling operation. This article reviews common waterside failure mechanisms in HRSGs, where they occur, and what can be done to prevent failures in the future. (orig.)

[en] The range of changing the velocity of switching heat waves propagation with an account of local nonlinearity of the specific electric resistance of the normal conducting matrix in the vicinity of the superconducting transition temperature in the superconducting composite is evaluated. The fundamental results on the wave propagation theory for the system of the parabolic-type equations were used by evaluating the switching wave velocities. The formulae for determining the switching heat waves propagation along the cooled composite superconductor in dependence on the size of the composite cover by a nonelectron shell are obtained. The value for the minimal current of the normal zone propagation is determined with an account of the local nonlinearity of the composite specific electric resistance

[en] This paper shows a possible way to achieve a thermoeconomic optimization of combined cycle gas turbine (CCGT) power plants. The optimization has been done using a genetic algorithm, which has been tuned applying it to a single pressure CCGT power plant. Once tuned, the optimization algorithm has been used to evaluate more complex plants, with two and three pressure levels in the heat recovery steam generator (HRSG). The variables considered for the optimization were the thermodynamic parameters that establish the configuration of the HRSG. Two different objective functions are proposed: one minimizes the cost of production per unit of output and the other maximizes the annual cash flow. The results obtained with both functions are compared in order to find the better optimization strategy. The results show that it is possible to find an optimum for every design parameter. This optimum depends on the selected optimization strategy

[en] Heat pumps, mainly the compression type, grant high energy savings together with environment protection because of the free low temperature energy from environment or wasted heat they use. Their large employment depends on the appreciation of the above properties that are will be done. To grant economic savings on using heat pumps, electric energy and natural gas should have fixed and predictable prices

[en] The feasibility of integrating a commercially available reheat gas turbine with a methane steam reformer is analyzed. A slight modification to the original reheat design is proposed to improve the methane conversion rate in the reforming process and, consequently, the efficiency in recovering waste exhaust heat from the gas turbine. Two solutions are proposed for the heat recovery scheme: a first reformer has a single pressure level while the second has two in order to match the different pressures of the combustors. While the single pressure scheme gives good performance with respect to the stand alone gas turbine, the dual pressure reformer can give a further benefit, as far as an accurate optimization of the steam management is performed

[en] This communication presents thermodynamic methodology for the performance evaluation of combustion gas turbine cogeneration system with reheat. The energetic and exergetic efficiencies have been defined. The effects of process steam pressure and pinch point temperature used in the design of heat recovery steam generator, and reheat on energetic and exergetic efficiencies have been investigated. From the results obtained in graphs it is observed that the power to heat ratio increases with an increase in pinch point, but the first-law efficiency and second-law efficiency decreases with an increase in pinch point. The power to heat ratio and second-law efficiency increases significantly with increase in process steam pressure, but the first-law efficiency decreases with the same. Results also show that inclusion of reheat, provide significant improvement in electrical power output, process heat production, fuel-utilization (energetic) efficiency and second-law (exergetic) efficiency. This methodology may be quite useful in the selection and comparison of combined energy production systems from thermodynamic performance point of view

[en] With the deregulation of the nitrogenous fertilizer industry in Pakistan in 1986, the scenario changed for major energy conservation projects. In addition the government also started escalating the prices of natural gas. At this point they reactivated their major energy conservations projects. The plant was designed prior to the energy crisis period at the point when energy consumption was not a very major consideration. As a result, many of the energy conserving features built into subsequent plants were not included. On the gas turbine side, several changes were required in order to allow that the installation of the HRSG's. The gas turbine had to be upgraded to allow air flow due to the increased back pressure following installation of the HRSG's. Also with the uprate, the gas turbine control system had to be upgraded. The off take ducks for the HRSGs also required a design modification on the gas turbine exhaust to allow for a flanged connection, and the silencers in the exhaust duct had to be removed. The savings of natural gas was as per projections. Presently, with auxiliary firing, the HRSG's are producing 140,000 pph of steam. Their site total gas consumption has reduced by 10.6% or approximately 4 to 4.4 million CFD. In addition, the HRGS's have also provided significant ease of operation and flexibility. Of the three offsite boilers, two have been shut down and only one is operational. (A.B.)

[en] In future perspective of energy supply, a hydrogen energy cycle is expected to play an important role as a CO₂ free fuel for mobile or co-generation systems. Fusion power plants should offer advantages, compatibilities and/or synergistic effects with or in such future energy systems. In this paper, a comprehensive power station, in which a fusion plant is integrated with a hydrogen production plant, is proposed. A tenuous heat source in the outboard shield, which is unsuitable to produce high-pressure and high-temperature steam for efficient electric power generation, is used for the hydrogen production. This integrated system provides some synergistic effects and it would be advantageous over any independent use of each plant. (author)

[en] Reduction of fuel consumption can be easily attained by different systems of energy recovery basically including sludge drying and/or power conversion using steam produced in the exhaust gas recovery boiler. Such alternatives are compared and discussed. It clearly appears that drying has to be performed possibly up to a concentration of 45.9% at 70 volatile solids (VS). Sensible heat of exhaust gases can be recovered in a boiler whose dimensioning can follow two different objectives: maximisation of steam production controlling gas exit temperature at 250⁰ C or production of steam just needed for thermal drying. Conversion in electrical energy can furnish 30-40% of electrical energy needed in the wastewater treatment plant when cake concentration before drying is 40%