Advanced S-CO2 Brayton Power Cycles in Nuclear and Fusion Energy

2019 ◽  
Author(s):  
Jan Syblik ◽  
Ladislav Vesely ◽  
Slavomir Entler ◽  
Vaclav Dostal ◽  
Jan Stepanek
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Initial Conditions ◽  
Fusion Energy ◽  
Systems Design ◽  
Thermodynamic Efficiency ◽  
Cooling Systems ◽  
Power Cycles ◽  
Power Cycle ◽  
Advantages And Disadvantages

Abstract Cooling system is one of the most important part of the power plants and cooling systems based on S-CO2 (Supercritical Carbon Dioxide) coolant seems nowadays perspective alternative to Helium and Rankine steam power cycles. Due to many advantages of S-CO2, these cooling systems are researched on many institutions and the results confirm that it should be successful for the future cooling systems design. One of the main objectives is comparison of the possible cooling mediums of DEMO2 (Demonstration power plant 2) with focusing on different power cycles with S-CO2. The First part of this article targets on comparison of three main coolants: steam, helium and S-CO2. The second part of this article focuses on the new software called CCOCS (Cooling Cycles Optimization Computational Software) which was developed on CTU in Prague. This software works on deeper optimization of the power cycles with various coolants and initial conditions. The third part describes advanced S-CO2 power cycles and enlarges past research, which was based on optimization of S-CO2 Brayton Simple power cycle and S-CO2 Re-compression power cycle both with recuperation and their usage in fusion and Fission energy engineering. It is possible to heighten thermodynamic efficiency of power cycle by changing the layout of the power cycle and the main objective of this paper is to compare four advanced layouts, describe the results of the optimization of these cycles and outline advantages and disadvantages of chosen optimized layouts.

Inlet Air Cooling Applied to Combined Cycle Power Plants: Influence of Site Climate and Thermal Storage Systems

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Nicola Palestra ◽  
Giovanna Barigozzi ◽  
Antonio Perdichizzi
Keyword(s):  
Power Output ◽  
Parametric Analysis ◽  
Power Plants ◽  
Cooling System ◽  
Thermal Storage ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Air Cooling ◽  
Ambient Conditions ◽  
Cooling Systems

The paper presents the results of an investigation on inlet air cooling systems based on cool thermal storage, applied to combined cycle power plants. Such systems provide a significant increase of electric energy production in the peak hours; the charge of the cool thermal storage is performed instead during the night time. The inlet air cooling system also allows the plant to reduce power output dependence on ambient conditions. A 127MW combined cycle power plant operating in the Italian scenario is the object of this investigation. Two different technologies for cool thermal storage have been considered: ice harvester and stratified chilled water. To evaluate the performance of the combined cycle under different operating conditions, inlet cooling systems have been simulated with an in-house developed computational code. An economical analysis has been then performed. Different plant location sites have been considered, with the purpose to weigh up the influence of climatic conditions. Finally, a parametric analysis has been carried out in order to investigate how a variation of the thermal storage size affects the combined cycle performances and the investment profitability. It was found that both cool thermal storage technologies considered perform similarly in terms of gross extra production of energy. Despite this, the ice harvester shows higher parasitic load due to chillers consumptions. Warmer climates of the plant site resulted in a greater increase in the amount of operational hours than power output augmentation; investment profitability is different as well. Results of parametric analysis showed how important the size of inlet cooling storage may be for economical results.

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.

Comparative Analysis of Conventional and Fuel Cell-Based Gas Turbine Power Plants

2013 ◽  
Author(s):  
Mohamed Gadalla ◽  
Nabil Al Aid
Keyword(s):  
Fuel Cell ◽  
Gas Turbine ◽  
Power Plants ◽  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Integrated System ◽  
Power Cycles ◽  
Technical Management ◽  
Advantages And Disadvantages ◽  
Gas Turbine Power Plant

The purpose of this paper is to conduct a complete comparative, energy and 2nd low analyses between different types of fuel cells integrated with a gas turbine power plant. Different levels of modeling for the solid oxide fuel cell (SOFC), the proton exchange membrane fuel cell (PEMFC) and the integrated systems are to be presented. The overall system performance is analyzed by employing individual models and further applying energy and exergetic analyses for different configurations of gas turbine power cycles. The study includes applying different proposed methods and techniques to enhance the overall efficiency of the integrated cycle. After performing the complete technical management of the complete system, a comparative study between conventional and PEMFC and SOFC cycles is investigated to highlight the corresponding advantages and disadvantages of each system. The following systems are tested and evaluated: (a) Conventional Gas Turbine System with a combustion Chamber (b) Integrated SOFC Stack into a Gas Turbine System (c) The Proposed Integrated System with both SOFC and PEMFC.

Turbine Cooling Systems Design: Past, Present and Future

2009 ◽  
Author(s):  
James P. Downs ◽  
Kenneth K. Landis
Keyword(s):  
Research And Development ◽  
Film Cooling ◽  
Gas Turbines ◽  
State Of The Art ◽  
Cooling System ◽  
Systems Design ◽  
Maximum Temperature ◽  
Cooling Systems ◽  
Cooling Flows ◽  
Turbine Cooling

Over a half a century ago, the power and performance of the first gas turbine engines were constrained by material limits on operating temperature. In these machines, the combustor exit temperature could not exceed the capability of the materials used to construct the turbine. Eventually, cooling was introduced into turbine components to enable turbine power and efficiency to be increased. That revolutionary step enabled gas turbines to become competitive with other heat engines for business, particularly in the rapidly expanding aviation and electrical power generation sectors. Although the first cooled turbine components may be considered crude by present standards, the underlying foundation of internal convection cooling remains the backbone for cooled turbine components today. Since its introduction, many improvements and additions to the fundamental basis of turbine component cooling have been developed. The introduction of film cooling is a prominent example. With this past research and development, turbine cooling system designs have progressed to the point where they represent the norm, rather than the exception in today’s gas turbines. Further, the confidence and robustness of these systems has been elevated to the point where the working fluid temperatures can exceed the maximum temperature of the structural materials by wide margins. In this paper, from an engineering perspective, we explore some of the significant accomplishments that have led to the current state-of-the-art in turbine cooling systems design. These systems employ a delicate balance of structural material capabilities with advanced internal and film cooling and the use of thermal barrier coatings to satisfy the goals and objectives of specific applications. At the same time, it is widely recognized that the use of cooling flows in the turbine results in parasitic losses that reduce performance. To that end, we also consider some of the specific challenges that face cooling system designers to reduce cooling flows today. Based on the research and development that has been performed to date, we consider the current status of cooling technology relative to a theoretical peak. Finally, we explore some of the hurdles that must be overcome to effectively raise the bar and realize future advancement of the state-of-the-art. The goal is to measure and separate new technologies that are merely different from those that are superior to past designs. Clearly, the identification of risk and risk reduction will play an important role in the development of future turbine cooling systems.

LNG Receiving Terminal Associated With Gas Cycle Power Plants

1997 ◽  
Author(s):  
Paolo Chiesa
Keyword(s):  
Gas Turbines ◽  
Power Plants ◽  
Sea Water ◽  
Initial Conditions ◽  
High Reliability ◽  
Low Cost ◽  
Long Distance ◽  
Power Cycles ◽  
Economical Analysis ◽  
Combined Cycles

LNG regasification process needs a considerable quantity of thermal energy that is usually obtained by cooling sea water or by burning a fraction of the evaporated natural gas. These systems, though offering low cost and high reliability, are thermodynamically inefficient: they require energy for water pumping or fuel to provide heat and do not exploit the physical exergy related to the initial conditions of LNG to produce mechanical work. The present paper aims to assess the performances of various gas turbine based cycles which use the LNG regasification process as a low temperature heat sink for power cycles. In particular it will focus on the following configurations: • Closed loop gas cycles • Gas-gas combined cycles • Combined gas-organic Rankine cycles Two different sendout pressure (70 and 30 bar, corresponding respectively to the supply of long-distance pipelines or power plants based on heavy-duty gas turbines) are considered. Their performances are calculated and proper effectiveness indexes (e.g. thermal and exergetic efficiency) are introduced to carry out a comprehensive comparison among the systems considered. A simple economical analysis completes the discussion.

Self-Propelling Cooling Systems: Back-Fitting Passive Cooling Functions to Existing Nuclear Power Plants

2012 ◽  
Author(s):  
Dominik von Lavante ◽  
Dietmar Kuhn ◽  
Ernst von Lavante
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Cooling System ◽  
Electrical Power ◽  
Reactor Core ◽  
Passive Cooling ◽  
Spent Fuel ◽  
Cooling Systems ◽  
Spent Fuel Pool

The present paper describes a back-fit solution proposed by RWE Technology GmbH for adding passive cooling functions to existing nuclear power plants. The Fukushima accidents have high-lighted the need for managing station black-out events and coping with the complete loss of the ultimate heat sink for long time durations, combined with the unavailability of adequate off-site supplies and adequate emergency personnel for days. In an ideal world, a nuclear power plant should be able to sustain its essential cooling functions, i.e. preventing degradation of core and spent fuel pool inventories, following a reactor trip in complete autarchy for a nearly indefinite amount of time. RWE Technology is currently investigating a back-fit solution involving “self-propelling” cooling systems that deliver exactly this long term autarchy. The cooling system utilizes the temperature difference between the hotter reactor core or spent fuel pond with the surrounding ultimate heat sink (ambient air) to drive its coolant like a classical heat machine. The cooling loop itself is the heat machine, but its sole purpose is to merely achieve sufficient thermal efficiency to drive itself and to establish convective cooling (∼2% thermal efficiency). This is realized by the use of a Joule/Brayton Cycle employing supercritical CO2. The special properties of supercritical CO2 are essential for this system to be practicable. Above a temperature of 30.97°C and a pressure of 73.7bar CO2 becomes a super dense gas with densities similar to that of a typical liquid (∼400kg/m3), viscosities similar tothat of a gas (∼3×105Pas) and gas like compressibility. This allows for an extremely compact cooling system that can drive itself on very small temperature differences. The presented parametric studies show that a back-fitable system for long-term spent fuel pool cooling is viable to deliver excess electrical power for emergency systems of approximately 100kW. In temperate climates with peak air temperatures of up to 35°C, the system can power itself and its air coolers at spent fuel pool temperatures of 85°C, although with little excess electrical power left. Different back-fit strategies for PWR and BWR reactor core decay heat removal are discussed and the size of piping, heat exchangers and turbo-machinery are briefly evaluated. It was found that depending on the strategy, a cooling system capable of removing all decay heat from a reactor core would employ piping diameters between 100–150mm and the investigated compact and sealed turbine-alternator-compressor unit would be sufficiently small to be integrated into the piping.

scholarly journals Comparison between OCl−-Injection and In Situ Electrochlorination in the Formation of Chlorate and Perchlorate in Seawater

2019 ◽  
Vol 9 (2) ◽  
pp. 229 ◽  
Author(s):  
Jongchan Yi ◽  
Yongtae Ahn ◽  
Moongi Hong ◽  
Gi-Hyeon Kim ◽  
Nisha Shabnam ◽  
...  
Keyword(s):  
Reaction Time ◽  
Electrode Material ◽  
Power Plants ◽  
Cooling System ◽  
Cooling Water ◽  
Injection System ◽  
No Production ◽  
Cooling Systems ◽  
Environmentally Friendly Method

To prevent biofouling from occurring in the cooling systems of coastal power plants, chlorine is often added to the cooling water. In this study, we have evaluated the fate of the total residual oxidants and the formation of inorganic chlorination byproducts including ClO3− and ClO4− during in situ electrochlorination with seawater. Then, the results were compared with those during direct OCl−-injection to seawater. The in situ electrochlorination method based on Ti/RuO2 electrodes produced much less ClO3−, while a similar level of total residual oxidants could be achieved with a reaction time of 5 min. Moreover, no ClO4− was observed, while the direct OCl−-injection system could still result in the production of ClO4−. The less or no production of ClO3− or ClO4− by the electrochlorination of seawater was mainly attributed to two reasons. First, during the electrolysis, the less amount of OCl− is available for ClO3− formation. Secondly, the formation of ClO3− or ClO4− is affected by the electrode material. In other words, if the electrode material is carefully chosen, the production of harmful reaction byproducts can be prevented or minimized. In short, based on the results from our study, electrochlorination technology proves to be a marine environmentally friendly method for controlling biofouling in the pipes of the cooling system in a coastal power plant.

Economic Design of Hybrid Wet-Dry Cooling Systems

2013 ◽  
Author(s):  
R. W. Card
Keyword(s):  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Weather Data ◽  
Net Generation ◽  
Steam Turbines ◽  
Cooling Systems ◽  
Hybrid Cooling ◽  
Seasonal Basis ◽  
Dry Cooling

A hybrid wet-dry cooling system can be designed for a large combined-cycle power plant. A well-designed hybrid cooling system will provide reasonable net generation year-round, while using substantially less water than a conventional wet cooling tower. The optimum design for the hybrid system depends upon climate at the site, the price of power, and the price of water. These factors vary on a seasonal basis. Two hypothetical power plants are modeled, using state-of-the-art steam turbines and hybrid cooling systems. The plants are designed for water-constrained sites incorporating typical weather data, power prices, and water prices. The principles for economic designs of hybrid cooling systems are demonstrated.

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.

Towards a Technoeconomic Framework for Estimating Cost-Performance Tradeoffs for Power Plants Incorporating Transformative Dry-Cooling Technologies

2016 ◽  
Author(s):  
Geoffrey Short ◽  
Addison K. Stark ◽  
Daniel Matuszak ◽  
James F. Klausner
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Fresh Water ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Cooling Systems ◽  
Natural Gas Combined Cycle ◽  
Evaporative Cooling System ◽  
Dry Cooling

Fresh water withdrawal for thermoelectric power generation in the U.S. is approximately 139 billion gallons per day (BGD), or 41% of total fresh water draw, making it the largest single use of fresh water in the U.S. Of the fresh water withdrawn for the power generation sector, 4.3 BGD is dissipated to the atmosphere by cooling towers and spray ponds. Dry-cooled power plants are attractive and sometimes necessary because they avoid significant withdrawal and consumption of freshwater resources that could otherwise be used for other purposes. This could become even more important when considering the potential effects of climate change (1). Additional benefits of dry-cooling include power plant site flexibility, reduced risk of water scarcity, and faster permitting (reducing project development time and cost). However, dry-cooling systems are known to be more costly and larger than their wet-cooling counterparts. Additionally, without the benefit of additional latent heat transfer through evaporation, the Rankine cycle condensing (cold) temperature for dry-cooling is typically higher than that for wet-cooling, affecting the efficiency of power production and the resultant levelized cost of electricity (LCOE). The Advanced Research Projects Agency - Energy (ARPA-E) has developed a technoeconomic analysis (TEA) model for the development of indirect dry-cooling systems employing steam condensation within a natural gas combined cycle power plant. The TEA model has been used to inform the Advanced Research in Dry-Cooling (ARID) Program on the performance metrics needed to achieve an economical dry-cooling technology. In order to assess the relationship between air-cooled heat exchanger (ACHX) performance, including air side heat transfer coefficient and pressure drop, and power plant economics, ARPA-E has employed a modified version of the National Energy Technology Laboratory (NETL) model of a 550 MW natural gas combined cycle (NGCC) plant employing an evaporative cooling system. The evaporative cooling system, including associated balance of system costs, was replaced with a thermodynamic model for an ACHX with the desired improved heat transfer performance and supplemental cooling and storage systems. Monte Carlo simulation determined an optimal ACHX geometry and associated ACHX cost. Allowing for an increase in LCOE of 5%, the maximum allowable additional cost of the supplemental cooling system was determined as a function of the degree of cooling of the working fluid required. This paper describes the methodologies employed in the TEA, details the results, and includes related models as supplemental material, while providing insight on how the open source tool might be used for thermal management innovation.

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