Gas-steam Power Plant Research Articles

Greenhouse gas emission measurement and economic analysis of Iran natural gas fired power plants

This study attempts to examine the natural gas fired power plants in Iran. The required data from natural gas fired power plants were gathered during 2008. The characteristics of thirty two gas turbine power plants and twenty steam power plants have been measured. Their emission factor values were then compared with the standards of Energy Protection Agency, Euro Union and World Bank. Emission factors of gas turbine and steam power plants show that gas turbine power plants have a better performance than steam power plants. For economic analysis, fuel consumption and environmental damages caused by the emitted pollutants are considered as cost functions; and electricity sales revenue are taken as benefit functions. All of these functions have been obtained according to the capacity factor. Total revenue functions show that gas turbine and steam power plants are economically efficient at 98.15% and 90.89% of capacity factor, respectively; this indicates that long operating years of power plants leads to reduction of optimum capacity factor. The stated method could be implemented to assess the economic status of a country’s power plants where as efficient capacity factor close to one means that power plant works in much better condition. • CO 2 and NO x emissions of Iran natural gas fired power plants have been studied. • CO 2 and NO x emission factors are compared with EPA, EU and World Bank standards. • Costs and benefit as economic functions are obtained according to capacity factor. • Maximum economic profit is obtained for gas turbine and steam power plants. • Investment in CO 2 reduction is recommended instead of investment in NO x reduction.

A comparison between exergetic and economic criteria for optimizing the heat recovery steam generators of gas-steam power plants

CCGT (Combined-cycle gas turbines) are gaining an increasingly important role in power generation thanks to their high thermal efficiency, low installed cost and ready availability. Increasing natural gas prices, the optimization of CCGT operating parameters is becoming a topic of growing interest.In this paper two different methodologies for optimizing CCGTs are compared. The first aims to minimize the cost per unit of electricity generated, the second to minimize an objective function based on exergoeconomic principles accounting for the costs related with thermodynamic inefficiencies.Optimization results have been obtained considering different CCGT configurations, with single or multi-pressure HRSG (heat recovery steam generators), and varying the gas turbine technology, fuel price and plant capacity factor. A modular approach has been adopted to design a highly effective and flexible HRSG layout, in terms of number of pressure levels and arrangement of heat exchange sections along the flue gas path, together with the corresponding energy, exergy and cost balances, using an “interaction matrix”, with nodes between elementary components and towards the surrounding environment.

A sustainable energy policy for Slovenia: Considering the potential of renewables and investment costs

In this paper, Slovenia's current energy policy is analyzed, the potential of renewable energy sources (RES) is evaluated and examined, and new options for the development of an alternative energy policy and the transition of the Slovenian energy industry into a sustainable energy industry are proposed and cross compared. On the basis of current and future electricity consumption, the evaluated RES potentials, and calculated investment prices, options for alternative investment projects and the alternative development of a more sustainable energy policy in Slovenia are identified. These possibilities and the current energy policy are analyzed and cross-compared from the economic and environmental viewpoint, with special emphasis on investment costs. At the end of the paper, the implementation costs of the proposed alternative energy policy investments are evaluated, calculated, and cross-compared, and the advantages and disadvantages of the alternative energy policy are evaluated. The proposed alternatives have significant benefits in comparison to the existing energy strategy, which focuses on a new lignite thermal power plant. Reconstruction of the existing thermal power plant in Šoštanj is a considerably cheaper alternative and a sound transitory solution for Slovenia. Investment in a multiple fuel power plant is also a cheaper and more efficient alternative, which, in addition, enables the usage of local biomass. Another considerably cheaper and more efficient alternative with lower emissions is a gas-steam power plant. The most promising alternative is found to be electricity production from local RES, resulting in a significant reduction of energy related emissions and domestic sources usage. The estimated investment costs for the last alternative are comparable to the costs for the implementation of Slovenia's current energy policy.

Liquefied natural gas submerged combustion vaporization facilities: process integration with power conversion units

Liquefied natural gas (LNG) vaporization facilities offer an excellent opportunity of primary energy saving by means of integration with power conversion units that is still weakly exploited in actual installations. This work focuses on the evaluation of primary energy saving achievable by the integration of an LNG vaporization facility with a gas turbine and with a cogenerative combined gas-steam power plant. The fuel energy saving ratio is used as the main performance parameter to evaluate the primary energy saving derived by system integration, with respect to conventional submerged combustion vaporization. Twelve possible configurations are analyzed with steady-state calculations. Results show that a primary energy saving greater than 15% with peak values up to 27%, corresponding to 2.98 TJ/year, is achievable. The paper shows that the fuel energy saving ratio can be used as a synthetic and effective parameter to estimate the energy-saving potential of different plant configurations. Copyright © 2011 John Wiley & Sons, Ltd.

Exergetic optimization of single level combined gas–steam power plants considering different objective functions

Combined cycle power plants have been studied in this paper with the aim of optimizing the heat recovery steam generator using a first and second law approach. To this end, a mathematical model has been developed for determining the optimal steam pressure in a one pressure level heat recovery steam generator, considering that the gas turbine is known. Different objective functions have been analysed in this study, some of which refer only to the exergy balance of the heat recovery steam generator while others involve the whole bottoming cycle. Some constraints for the operating parameters of the power plant have also been taken into account, regarding for instance the steam quality at the turbine outlet and the steam turbine blade height. Some numerical results have been reported in the paper, comparing the different objective functions for heat recovery steam generators coupled with several gas turbines; the developed parametric analysis has been performed in order to evaluate the influence of some parameters on both the heat recovery steam generator and the whole bottoming cycle.

A unified approach to assess performance of different techniques for recovering exhaust heat from gas turbines

Exhaust heat from gas turbines can be recovered externally or internally to the cycle itself. Of the technology options for external recovery, the combined gas–steam power plant is by far the most effective and commonly used worldwide. For internal recovery conventional solutions are based on thermodynamic regeneration and steam injection, while innovative solutions rely on humid air regeneration and steam reforming of fuel. In this paper a unified approach for analysing different exhaust heat recovery techniques is proposed. It has been possible to define a characteristic internal heat recovery plane, based on a few meaningful parameters and to identify an innovative scheme for repowering existing combined cycles. The characteristic plane indicates directly the performance obtainable with the different recovery techniques, showing that performances close to combined cycle plants (external recovery) can only be achieved with combined recovery techniques (humid air regeneration, steam reforming of fuel). The innovative repowering scheme, which requires the addition of a gas turbine and one-pressure level HRSG to an existing combined gas–steam power plant, significantly increases power output with fairly high marginal efficiency.

Analysis of energy-conversion processes in gas–steam power-plants integrated with coal gasification

The paper presents the complex energy analysis of technological systems of gas–steam power plants integrated with coal gasification. The bases of the performed energy analyses are the elaborate mathematical models describing the behaviour of main elements of the gas-steam power plants integrated with coal gasification, such as the gas generator, raw-gas cooler with the gas desulphurisation system, compressor, combustion chamber, gas turbine, heat-recovery steam-generator and steam-turbine cycle. The influence of coal-gasification technology, coal type, gasifying medium, fuel-desulphurisation technology and gas-turbine design on the efficiency of electric-energy generation were taken into account.

99/02510 First experience with gas—steam power plants using coal gasification gas

99/02510 First experience with gas—steam power plants using coal gasification gas

97/01870 Modeling and simulation of energy conversion in combined gas-steam power plant integrated with coal gasification

97/01870 Modeling and simulation of energy conversion in combined gas-steam power plant integrated with coal gasification

97/01560 Modeling and simulation of energy conversion in combined gas-steam power plant integrated with coal gasification

The generation of electric power through the conventional conversion systems may no longer be sufficient to keep pace with the increasing electricity usage and demands. Therefore, an enhancement to these systems can be made by incorporating a topping unit to the existing power plants (thermal, hydroelectric), a direct energy conversion system. Among such is the Magnetohydrodynamics (MHD) system. In an MHD conversion system, electricity is generated when heat energy is converted into electrical energy without the use of mechanical rotating parts. Additionally, the heat energy (ionised gas) required inside the MHD system usually comes from the combustion of fossil fuels. However, this system is still under development in developing countries like South Africa. The current study aims to investigate through simulations and theoretical modelling two existing Open-Cycle Gas Turbines (OCGT) in South Africa (Ankerlig and Gourikwa), which can be converted into Combined-Cycle MHD Gas-Steam Turbines (CCMGST). The processes involved by incorporating the MHD system with these conventional turbines have been further discussed. With setting up a CCMGST in South Africa, the obtained modelling results project an additional generation of electric power which will further improve the existing power generation.

Steam Cycle Regeneration Influence on Combined Gas-Steam Power Plant Performance

The influence of steam cycle regeneration on combined plant performance has been analyzed from the thermodynamic point of view. A mathematical model has been developed and calculations have been performed according to a cycle analysis criterion. The higher the number of extractions the lower the relative efficiency gain. The influence of the intermediate feedwater temperatures is very small when these temperatures are slightly changed in relation to the equally spaced values. Results are given for a gas turbine firing temperature equal to 1000°C. They show a positive influence on combined cycle efficiency for small regeneration degrees. Gas turbine firing temperature in the range of 800–1400°C has been considered. The influence of the economizer inlet temperature lower limit is shown.

Computer control of combined-cycle power plants: Complete automation and coordination of the plant is possible — From startup through loading, and from full load to shutdown

Complete automation and coordination of the combined gas-steam power plant is possible, from startup through loading, and from full load to shutdown. The control systems described start each piece of equipment, accelerate and synchronize the turbine generators, and direct a complete plant shutdown in the event of a normal stop mode. Software in the system controls gas-turbine blade temperature and regulates steam-throttle pressure.