Pre-Design Studies of Cycles With Energy, Exergy, Thermoeconomy and ELCA Analysis

2002 ◽  
Author(s):  
Ahmad R. Azimian ◽  
Pernilla L. Olausson ◽  
Mohsen Assadi
Keyword(s):  
Power Plants ◽  
High Efficiency ◽  
Cost Effective ◽  
Combined Cycle ◽  
Design Studies ◽  
Environmental Friendliness ◽  
Power Cycles ◽  
Power Cycle ◽  
Air Turbine ◽  
Power Generation Systems

High efficiency, environmental friendliness, low operation and maintenance (O&M) costs, and lowest possible impact on the surroundings are some requirements of sustainable energy production. In selection of new power generation systems, a number of steps have to be taken into account to meet these requirements. Here the first law analysis has been implemented and investigated followed by a combination of the first and second law analyses (exergy analysis), and thermoeconomics, and finally an Exergetic Life Cycle Assessment (ELCA) is carried out for two different power cycles. The two cycles, investigated here, are a two-pressure level combined cycle, hereafter called (CC), and a Humid Air Turbine or (HAT-cycle). The main goal of this study is to point out the advantages and the difficulties related to the usage of each and every method and their combinations, and to identify the target groups that can gain knowledge and information using these methods. Since the operators of power plants often do not have access to detailed information about component materials, characteristics, etc., of the power cycle, assumptions have to be made when comparing different cycle configuration with each other. This limited type of data and information has also been used here to create a plausible scenario of how different pre-design methods can differ from each other. One major conclusion that has been drawn is that the two cycles investigated here are favorable in different situations and that the results from application of the three methods mentioned above indicate differences in which cycle is the preferable one. However, using a combination of different analysis methods illuminates the plant strengths and limitations during pre-design studies, but conflicting results need to be resolved to obtain the most cost effective and environmentally-friendly power cycle.

Research on Thermal Efficiencies of Various Power Cycles for GFRs and VHTRs

2018 ◽  
Author(s):  
Mohammed Mahdi ◽  
Roman Popov ◽  
Igor Pioro
Keyword(s):  
Gas Turbine ◽  
Heavy Water ◽  
Nuclear Power ◽  
Power Plants ◽  
Supercritical Pressure ◽  
Combined Cycle ◽  
Power Cycles ◽  
Power Cycle ◽  
Combined Cycles ◽  
Gas Turbine Cycle

The vast majority of Nuclear Power Plants (NPPs) are equipped with water- and heavy-water-cooled reactors. Such NPPs have lower thermal efficiencies (30–36%) compared to those achieved at NPPs equipped with Advanced Gas-cooled Reactors (AGRs) (∼42%) and Sodium-cooled Fast Reactors (SFRs) (∼40%), and, especially, compared to those of modern advanced thermal power plants, such as combined cycle with thermal efficiencies up to 62% and supercritical-pressure coal-fired power plants — up to 55%. Therefore, NPPs with water- and heavy-water-cooled reactors are not very competitive with other power plants. Therefore, this deficiency of current water-cooled NPPs should be addressed in the next generation or Generation-IV nuclear-power reactors / NPPs. Very High Temperature Reactor (VHTR) concept / NPP is currently considered as the most efficient NPP of the next generation. Being a thermal-spectrum reactor, VHTR will use helium as a reactor coolant, which will be heated up to 1000°C. The use of a direct Brayton helium-turbine cycle was considered originally. However, technical challenges associated with the direct helium cycle have resulted in a change of the reference concept to indirect power cycle, which can be also a combined cycle. Along with the VHTR, Gas-cooled Fast Reactor (GFR) concept / NPP is also regarded as one of the most thermally efficient concept for the upcoming generation of NPPs. This concept was also originally thought to be with the direct helium power cycle. However, technical challenges have changed the initial idea of power cycle to a number of options including indirect Brayton cycle with He-N2 mixture, application of SuperCritical (SC)-CO2 cycles or combined cycles. The objective of the current paper is to provide the latest information on new developments in power cycles proposed for these two helium-cooled Generation-IV reactor concepts, which include indirect nitrogen-helium Brayton gas-turbine cycle, supercritical-pressure carbon-dioxide Brayton gas-turbine cycle, and combined cycles. Also, a comparison of basic thermophysical properties of helium with those of other reactor coolants, and with those of nitrogen, nitrogen-helium mixture and SC-CO2 is provided.

Process Simulations of the Cold Recovery Unit in a LNG CCHP System with Different Power Cycles

2011 ◽  
Vol 90-93 ◽  
pp. 3026-3032
Author(s):  
Heng Sun ◽  
Hong Mei Zhu ◽  
Hong Wei Liu
Keyword(s):  
Energy Efficiency ◽  
High Efficiency ◽  
Rankine Cycle ◽  
Primary Energy ◽  
Combined Cycle ◽  
Power Cycles ◽  
Power Cycle ◽  
Recovery Unit ◽  
Cold Energy ◽  
Cooling Media

A CCHP system using LNG as the primary energy should integrate cold recovery unit to increase the total energy efficiency. A scheme of CCHP consisting of gas turbine-steam turbine combined cycle, absorption refrigeration unit, cold recovery unit and cooling media system is a system with high efficiency and operation flexibility. Three different power cycles using the cold energy of LNG is(are 或 were) presented and simulated. The results show that the cascade Rankine power cycle using ethylene and propane in the two cycles respectively has highest energy efficiency. However, the unit is most complex. The efficiency of ethylene Rankine power cycle is little lower than the cascade one, and is much higher than the traditional propane Rankine cycle. The complexity of ethylene cycle is identical to that of the propane cycle. The ethylene Rankine power cycle is the referred method of cold recovery in a CCHP system based on overall considerations.

Comparison of Supercritical CO2 Power Cycles to Steam Rankine Cycles in Coal-Fired Applications

2017 ◽  
Author(s):  
Jason D. Miller ◽  
David J. Buckmaster ◽  
Katherine Hart ◽  
Timothy J. Held ◽  
David Thimsen ◽  
...  
Keyword(s):  
Power Plants ◽  
Cooling Tower ◽  
Test Case ◽  
Test Cases ◽  
Power Cycles ◽  
Air Preheater ◽  
Power Cycle ◽  
Inlet Conditions ◽  
Cycle Efficiency ◽  
Steam Plant

Increasing the efficiency of coal-fired power plants is vital to reducing electricity costs and emissions. Power cycles employing supercritical carbon dioxide (sCO2) as the working fluid have the potential to increase power cycle efficiency by 3–5% points over state-of-the-art oxy-combustion steam-Rankine cycles operating under comparable conditions. To date, the majority of studies have focused on the integration and optimization of sCO2 power cycles in waste heat, solar, or nuclear applications. The goal of this study is to demonstrate the potential of sCO2 power cycles, and quantify the power cycle efficiency gains that can be achieved versus the state-of-the-art steam-Rankine cycles employed in oxy-fired coal power plants. Turbine inlet conditions were varied among the sCO2 test cases and compared with existing Department of Energy (DOE)/National Energy Technology6 Laboratory (NETL) steam base cases. Two separate sCO2 test cases were considered and the associated flow sheets developed. The turbine inlet conditions for this study were chosen to match conditions in a coal-fired ultra-supercritical steam plant (Tinlet = 593°C, Pinlet = 24.1 MPa) and an advanced ultra-supercritical steam plant (Tinlet = 730°C, Pinlet = 27.6 MPa). A plant size of 550 MWe, was selected to match available information on existing DOE/NETL bases cases. The effects of cycle architecture, combustion-air preheater temperature, and cooling source type were considered subject to comparable heat source and reference conditions taken from the steam Rankine reference cases. Combinations and variants of sCO2 power cycles — including cascade and recompression and variants with multiple reheat and compression steps — were considered with varying heat-rejection subsystems — air-cooled, direct cooling tower, and indirect-loop cooling tower. Where appropriate, combustion air preheater inlet temperature was also varied. Through use of a multivariate nonlinear optimization design process that considers both performance and economic impacts, curves of minimum cost versus efficiency were generated for each sCO2 test case and combination of architecture and operational choices. These curves indicate both peak theoretical efficiency and suggest practical limits based on incremental cost versus performance. For a given test case, results for individual architectural and operational options give insight to cost and performance improvements from step-changes in system complexity and design, allowing down selection of candidate architectures. Optimized designs for each test case were then selected based on practical efficiency limits within the remaining candidate architectures and compared to the relevant baseline steam plant. sCO2 cycle flowsheets are presented for each optimized design.

scholarly journals The energy future of Saudi Arabia

2020 ◽  
Vol 181 ◽  
pp. 03005 ◽  
Author(s):  
Alberto Boretti ◽  
Stefania Castelletto ◽  
Wael Al-Kouz ◽  
Jamal Nayfeh
Keyword(s):  
Saudi Arabia ◽  
Energy Storage ◽  
Power Plants ◽  
High Efficiency ◽  
Thermal Power ◽  
Carbon Capture And Storage ◽  
Combined Cycle ◽  
Solar Photovoltaic ◽  
Battery Storage ◽  
Novel Technologies

In a recent publication, North European experts argue that “Saudi Arabia can achieve a 100% renewable energy power system by 2040 with a power sector dominated by PV single-axis tracking and battery storage”. They also say “Battery storage contributed up to 30% of the total electricity demand in 2040 and the contribution increases to 48% by 2050”. Based on considerations specific to the geography, climate conditions, and resources of Saudi Arabia, it is explained as batteries and photovoltaic solar panels are not the best choice for the country's energy sector. To cover all the total primary energy supply of Saudi Arabia by solar photovoltaic, plus battery storage to compensate for the sun's energy intermittency, unpredictability, and seasonal variability, is impracticable and inconvenient, for both the economy and the environment. Better environment and economy may be achieved by further valorizing the fossil fuel resources, through the construction of other high-efficiency plants such as the combined cycle gas turbine plants of Qurayyah, development of novel technologies for the production of clean fuels and clean electricity, including oxyfuel combustion and carbon capture and storage. Construction of nuclear power plants may also be more beneficial to the economy and the environment than photovoltaic and batteries. Regarding solar energy, enclosed trough solar thermal power systems developed along the coast have much better perspectives than solar photovoltaic, as embedded thermal energy storage is a better approach than battery storage. Further, a centralized power plant works better than distributed rooftop photovoltaic installations covered by dust and sand, rusted or cracked. Finally, pumped hydro energy storage along the coast may also have better perspectives than battery storage.

Hybrid Heat Engines: The Power Generation Systems of the Future

2000 ◽  
Author(s):  
Abbie Layne ◽  
Scott Samuelsen ◽  
Mark Williams ◽  
Patricia Hoffman
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Power Plants ◽  
Technology Development ◽  
Heat Engine ◽  
Combined Cycle ◽  
Heat Engines ◽  
Hybrid Concept ◽  
Hybrid Program ◽  
Power Generation Systems

A hybrid heat engine results from the fusion of a heat engine with a non-heat-engine based cycle (unlike systems). The term combined cycle, which refers to similar arrangements, is reserved for the combination of two or more heat engines (like systems). The resulting product of the integration of a gas turbine and a fuel cell is referred to here as a hybrid heat engine or “Hybrid” for short. The intent of this paper is to provide, to the gas turbine community, a review of the present status of hybrid heat engine technologies. Current and projected activities associated with this emerging concept are also presented. The National Energy Technology Laboratory (NETL) is collaborating with other sponsors and the private sector to develop a Hybrid Program. This program will address the issues of technology development, integration, and ultimately the demonstration of what may be the most efficient of power plants in the world — the Hybrid System. Analyses of several Hybrid concepts have indicated the potential of ultra-high efficiencies (approaching 80%). In the Hybrid, the synergism between the gas turbine and fuel cell provides higher efficiencies and lower costs than either system can alone. Testing of the first Hybrid concept has been initiated at the National Fuel Cell Research Center (NFCRC).

Enhancing Gas Turbine Operation With Heavy Fuel Oil

2013 ◽  
Author(s):  
Vikram Muralidharan ◽  
Matthieu Vierling
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Power Plants ◽  
High Efficiency ◽  
Combined Cycle ◽  
Fuel Oil ◽  
Residual Oil ◽  
Heavy Fuel Oil ◽  
Hydro Power

Power generation in south Asia has witnessed a steep fall due to the shortage of natural gas supplies for power plants and poor water storage in reservoirs for low hydro power generation. Due to the current economic scenario, there is worldwide pressure to secure and make more gas and oil available to support global power needs. With constrained fuel sources and increasing environmental focus, the quest for higher efficiency would be imminent. Natural gas combined cycle plants operate at a very high efficiency, increasing the demand for gas. At the same time, countries may continue to look for alternate fuels such as coal and liquid fuels, including crude and residual oil, to increase energy stability and security. In over the past few decades, the technology for refining crude oil has gone through a significant transformation. With the advanced refining process, there are additional lighter distillates produced from crude that could significantly change the quality of residual oil used for producing heavy fuel. Using poor quality residual fuel in a gas turbine to generate power could have many challenges with regards to availability and efficiency of a gas turbine. The fuel needs to be treated prior to combustion and needs a frequent turbine cleaning to recover the lost performance due to fouling. This paper will discuss GE’s recently developed gas turbine features, including automatic water wash, smart cooldown and model based control (MBC) firing temperature control. These features could significantly increase availability and improve the average performance of heavy fuel oil (HFO). The duration of the gas turbine offline water wash sequence and the rate of output degradation due to fouling can be considerably reduced.

Intercooled Advanced Gas Turbines in Coal Gasification Plants, With Combined or “HAT” Power Cycle

1997 ◽  
Author(s):  
Paolo Chiesa ◽  
Giovanni Lozza
Keyword(s):  
Gas Turbines ◽  
Coal Gasification ◽  
High Efficiency ◽  
Combined Cycle ◽  
Air Separation ◽  
Heavy Duty ◽  
Power Cycle ◽  
Efficiency Assessment ◽  
The One ◽  
Conversion Efficiencies

Due to their high efficiency and flexibility, aeroderivative gas turbines were often considered as a development basis for intercooled engines, thus providing better efficiency and larger power output. Those machines, originally studied for natural gas, are here considered as the power section of gasification plants for coal and heavy fuels. This paper investigates the matching between intercooled gas turbine, in complex cycle configurations including combined and HAT cycles, and coal gasification processes based on entrained-bed gasifiers, with syngas cooling accomplished by steam production or by full water-quench. In this frame, a good level of integration can be found (i.e. re-use of intercooler heat, availability of cool, pressurized air for feeding air separation units, etc.) to enhance overall conversion efficiency and to reduce capital cast. Thermodynamic aspects of the proposed systems are investigated, to provide an efficiency assessment, in comparison with mare conventional IGCC plants based on heavy-duty gas turbines. The results outline that elevated conversion efficiencies can be achieved by moderate-size intercooled gas turbines in combined cycle, while the HAT configuration presents critical development problems. On the basis of a preliminary cost assessment, cost of electricity produced is lower than the one obtained by heavy-duty machines of comparable size.

scholarly journals Thermodynamic and Techno-Economic Analyses of a Combined Cycle Power Plant With a Simple Cycle Gas Turbine, the Bottoming Air Turbine Cycle and the Reverse Brayton Cycle

1999 ◽  
Author(s):  
Isaac Shnaid
Keyword(s):  
Gas Turbine ◽  
Power Plants ◽  
Combined Cycle ◽  
Simple Cycle ◽  
Brayton Cycle ◽  
Cycle System ◽  
Air Turbine ◽  
Attractive Option ◽  
Gas Turbine Exhaust ◽  
Economic Analyses

The modem combined cycle power plants achieved thermal efficiency of 50–55% by applying bottoming multistage Rankine steam cycle. At the same time, the Brayton cycle is an attractive option for a bottoming cycle engine. In the author’s US Patent No. 5,442,904 is described a combined cycle system with a simple cycle gas turbine, the bottoming air turbine Brayton cycle, and the reverse Brayton cycle. In this system, air turbine Brayton cycle produces mechanic power using exergy of gas turbine exhaust gases, while the reverse Brayton cycle refrigerates gas turbine inlet air. Using this system, supercharging of gas turbine compressor becomes possible. In the paper, thermodynamic optimization of the system is done, and the system techno-economic characteristics are evaluated.

The Gas Turbine Family GT13E and GT13E2 Provides Reliable Power for Asia

1996 ◽  
Author(s):  
Gregor Gnädig
Keyword(s):  
Power Generation ◽  
Gas Turbines ◽  
Power Plants ◽  
High Efficiency ◽  
Operating Experience ◽  
Diesel Oil ◽  
Combined Cycle ◽  
Asian Countries ◽  
High Efficient ◽  
Prime Movers

Many Asian countries are experiencing economic growth which averages 5–10% per year. This environment has led to a privatization process in the power generation industry from typically state-run utilities to a system in which a federal agency oversees a market divided by private utilities and independent power producers (IPP) with the need for high efficiency, reliable power generation running on natural gas and diesel oil. In the 50 Hz market, modem, high efficient gas turbines of the type GT13E and GT13E2 have been chosen as prime movers in many combined cycle power plants in Asian countries. This paper includes a product description, and a general overview of GT13E and GT13E2 operating experience, well as an economic evaluation of a typical 500 MW combined cycle power plant.

Improving Plant Efficiency While Optimizing Water Use in Simple and Combined Cycle Power Plants

2008 ◽  
Author(s):  
Peter G. Demakos
Keyword(s):  
Power Plants ◽  
Closed Loop ◽  
Cost Effective ◽  
Poor Quality ◽  
Combined Cycle ◽  
Cooling Systems ◽  
Scarce Water ◽  
Quality Water ◽  
Poor Quality Water ◽  
Plant Efficiency

Closed-loop, evaporative cooling systems (Wet Surface Air Coolers) are a cost-effective heat transfer technology (for cooling and condensing) in simple and combined cycle power plants that also optimize use of scarce water resources. In addition to providing lower outlet temperatures and requiring less space and horsepower (HP), the WSAC can use poor quality water as spray makeup.

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