scholarly journals Analyses of the Costs Associated With Very High Turbine Entry Temperatures in Helium Recuperated Gas Turbine Cycles for Generation IV Nuclear Power Plants

Author(s):  
A. Gad-Briggs ◽  
P. Pilidis ◽  
T. Nikolaidis

Previous analyses of generation IV (GEN IV) helium gas turbine cycles indicated the possibility for high turbine entry temperatures (TETs) up to 1200 °C in order to improve cycle efficiency, using improved turbine blade material and optimum turbine cooling fractions. The purpose of this paper is to understand the effect on the levelized unit electricity cost (LUEC) of the nuclear power plant (NPP), when the TET is increased to 1200 °C from an original TET of 950 °C and when an improved turbine blade material is used to reduce the turbine cooling fraction. The analyses focus on the simple cycle recuperated (SCR) and the intercooled cycle recuperated (ICR). The baseline LUECs of the NPPs were calculated as $61.84/MWh (SCR) and $62.16/MWh for a TET of 950 °C. The effect of changing the turbine blades improved the allowable blade metal temperature by 15% with a reduction in the LUEC by 0.6% (SCR) and 0.7% (ICR). Furthermore, increasing the TET to 1200 °C has a significant effect on the power output but more importantly it reduces the LUECs by 22.7% (SCR) and 19.8% (ICR). The analyses intend to aid development of the SCR and ICR including improving the decision making process on choice of cycles applicable to the gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs), where helium is the coolant.

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Arnold Gad-Briggs ◽  
Emmanuel Osigwe ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis ◽  
Suresh Sampath ◽  
...  

Abstract Numerous studies are on-going on to understand the performance of generation IV (Gen IV) nuclear power plants (NPPs). The objective is to determine optimum operating conditions for efficiency and economic reasons in line with the goals of Gen IV. For Gen IV concepts such as the gas-cooled fast reactors (GFRs) and very-high temperature reactors (VHTRs), the choice of cycle configuration is influenced by component choices, the component configuration and the choice of coolant. The purpose of this paper to present and review current cycles being considered—the simple cycle recuperated (SCR) and the intercooled cycle recuperated (ICR). For both cycles, helium is considered as the coolant in a closed Brayton gas turbine configuration. Comparisons are made for design point (DP) and off-design point (ODP) analyses to emphasize the pros and cons of each cycle. This paper also discusses potential future trends, include higher reactor core outlet temperatures (COT) in excess of 1000 °C and the simplified cycle configurations.


Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis

A framework – NuTERA (Nuclear Techno-Economic and Risk Assessment) has been developed to set out the requirements for evaluating Generation IV (Gen IV) Nuclear Power Plants (NPPs) at the design conceptual stage. The purpose of the framework is to provide guidelines for future tools that are required to support the decision-making process on the choice of Gen IV concepts and cycle configurations. In this paper, the underpinning of the framework has been demonstrated to enable the creation of an analyses tool, which evaluates the design of an NPP that utilises helium closed Brayton gas turbine cycles. The tool at the broad spectrum focuses on the component and cycle design, Design Point (DP) and Off-Design Point (ODP) performance, part power and load following operations. Specifically, the design model has been created to provide functionalities that look at the in-depth sensitivities of the design factors and operation that affect the efficiency of an NPP such as temperature and pressure ratios, inlet cycle temperatures, component efficiencies, pressure losses. The ODP performance capabilities include newly derived component maps for the reactor, intercooler and recuperator for long term Off-Design (OD) operation. With regard to short term OD, which is typically driven by changes in ambient conditions, the ability to analyse the cycle load following capabilities are possible. An economic model has also been created, which calculates the component costs and the baseline economic evaluation. An incorporated risk model quantifies the performance, operational, financial and design impact risks. However, the tool is able to optimise the NPP cycle configuration based on the best economics using the Levelised Unit Electricity Cost (LUEC) as a measure. The tool has been used to demonstrate a typical decision-making process on 2 Gen IV helium closed gas turbine cycles, which apply to the Gas-cooled Fast Reactors (GFRs) and Very-High Temperature Reactors (VHTRs). The cycles are the Simple Cycle Recuperator (SCR) and Intercooled Cycle Recuperator (ICR). The tool was able to derive the most efficient cycle configurations for the ICR (53% cycle efficiency) and SCR (50% cycle efficiency). Based on these efficiency figures, the baseline LUEC ($/MWh) for the year 2020 is $62.13 for the ICR and $61.84 for the SCR. However, the inclusion of the cost of contingencies due to risks and the subsequent economic optimisation resulted in a cost of $69.70 and $69.80 for the ICR and SCR respectively.


Author(s):  
A. Gad-Briggs ◽  
P. Pilidis ◽  
T. Nikolaidis

The potential for high turbine entry temperature (TETs) turbines for nuclear power plants (NPPs) requires improved materials and sophisticated cooling. Cooling is critical for maintaining mechanical integrity of the turbine for temperatures >1000 °C. Increasing TET is one of the solutions for improving efficiency after cycle optimum pressure ratios have been achieved but cooling as a percentage of mass flow will have to increase, resulting in cycle efficiency penalties. To limit this effect, it is necessary to know the maximum allowable blade metal temperature to ensure that the minimum cooling fraction is used. The main objective of this study is to analyze the thermal efficiencies of four cycles in the 300–700 MW class for generation IV NPPs, using two different turbines with optimum cooling for TETs between 950 and 1200 °C. The cycles analyzed are simple cycle (SC), simple cycle recuperated (SCR), intercooled cycle (IC), and intercooled cycle recuperated (ICR). Although results showed that deterioration of cycle performance is lower when using improved turbine material, the justification to use optimum cooling improves the cycle significantly when a recuperator is used. Furthermore, optimized cooling flow and the introduction of an intercooler improve cycle efficiency by >3%, which is >1% more than previous studies. Finally, the study highlights the potential of cycle performance beyond 1200 °C for IC. This is based on the IC showing the least performance deterioration. The analyses intend to aid development of cycles for deployment in gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs).


2019 ◽  
Vol 5 (4) ◽  
Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis

The simple cycle recuperated (SCR) and intercooled cycle recuperated (ICR) are highly efficient Brayton helium gas turbine cycles, designed for the gas-cooled fast reactor (GFR) and very-high-temperature reactor (VHTR) generation IV (Gen IV) nuclear power plants (NPPs). This paper documents risk analyses, which consider technical and economic aspects of the NPP. The sensitivity analyses are presented that interrogate the plant design, performance, and operational schedule and range from component efficiencies, system pressure losses, operating at varied power output due to short-term load-following or long-term reduced power operations to prioritize other sources such as renewables. The sensitivities of the economic and construction schedule are also considered in terms of the discount rates, capital and operational costs, and increased costs in decontamination and decommissioning (D&D) activity due to changes in the discount rates. This was made possible by using a tool designed for this study to demonstrate the effect on the “noncontingency” baseline levelized unit electricity cost (LUEC) of both cycles. The SCR with a cycle efficiency of 50% has a cheaper baseline LUEC of $58.41/MWh in comparison to the ICR (53% cycle efficiency), which has an LUEC of $58.70/MWh. However, the cost of the technical and economic risks is cheaper for the ICR resulting in a final LUEC of $70.45/MWh (ICR) in comparison to the SCR ($71.62/MWh) for the year 2020 prices.


Author(s):  
Nicolai Neumann ◽  
Dieter Peitsch ◽  
Arne Berthold ◽  
Frank Haucke ◽  
Panagiotis Stathopoulos

Abstract Performance improvements of conventional gas turbines are becoming increasingly difficult and costly to achieve. Pressure Gain Combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycle. Previous cycle analyses considering turbine cooling methods have shown that the application of pressure gain combustion may require more turbine cooling air. This has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsed impingement jets inside the turbine blades. In the first part of this paper, results of pulsed impingement cooling experiments on a curved plate are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is quantified. The second part of this paper presents a gas turbine cycle analysis where the improved cooling approach is incorporated in the cooling air calculation. The effect of pulsed impingement cooling on the overall cycle efficiency is shown for both Joule and PGC cycles. In contrast to the authors’ anticipation, the results suggest that for relevant thermodynamic cycles pulsed impingement cooling increases the thermal efficiency of Joule cycles more significantly than it does in the case of PGC cycles. Thermal efficiency improvements of 1.0 p.p. for pure convective cooling and 0.5 p.p. for combined convective and film with TBC are observed for Joule cycles. But just up to 0.5 p.p. for pure convective cooling and 0.3 p.p. for combined convective and film cooling with TBC are recorded for PGC cycles.


2018 ◽  
Vol 2 (1) ◽  

The major growth in the electricity production industry in the last 30 years has centered on the expansion of natural gas power plants based on gas turbine cycles. The most popular extension of the simple Brayton gas turbine has been the combined cycle power plant with the Air-Brayton cycle serving as the topping cycle and the Steam-Rankine cycle serving as the bottoming cycle for new generation of nuclear power plants that are known as GEN-IV. The Air-Brayton cycle is an open-air cycle and the Steam-Rankine cycle is a closed cycle. The air-Brayton cycle for a natural gas driven power plant must be an open cycle, where the air is drawn in from the environment and exhausted with the products of combustion to the environment. This technique is suggested as an innovative approach to GEN-IV nuclear power plants in form and type of Small Modular Reactors (SMRs). The hot exhaust from the AirBrayton cycle passes through a Heat Recovery Steam Generator (HSRG) prior to exhausting to the environment in a combined cycle. The HRSG serves the same purpose as a boiler for the conventional Steam-Rankine cycle [1].


2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Theoklis Nikolaidis ◽  
Pericles Pilidis ◽  
Suresh Sampath

Abstract A significant hurdle in the development of performance simulation tools to analyze and evaluate nuclear power plants (NPP) is finding data relating to component performance maps. As a result, engineers often rely on an estimation approach using various scaling techniques. The purpose of this study is to determine the component characteristics of a closed-cycle gas turbine NPP using the existing component maps with the corresponding design data. The design data are applied for different working fluids using a multifluid scaling approach to adapt data from one component map into another. The multifluid scaling technique described herein was developed as an in-house computer simulation tool. This approach makes it easy to theoretically scale the existing maps using similar or different working fluids without carrying out a full experimental test or repeating the whole design and development process. The results of selected case studies show a reasonable agreement with the available data. The analyses intend to aid the development of cycles for Generation IV NPPs specifically gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs).


Author(s):  
Arnold Gad-Briggs ◽  
Pericles Pilidis ◽  
Theoklis Nikolaidis

Studies are currently on-going on the cycle performance of Generation IV (Gen IV) Nuclear Power Plants (NPPs) for the purpose of determining optimum operating conditions for efficiency and economic reasons. For Gas-cooled Fast Reactors (GFRs) and Very-High Temperature Reactors (VHTRs), the cycle layout is predominantly driven by the choice of components, the component configuration and the coolant. The purpose of this paper to present and review the cycles currently being considered — the Simple Cycle Recuperated (SCR) and the Intercooled Cycle Recuperated (ICR). In all cases, the cycles utilise helium as the coolant in a closed Brayton gas turbine configuration. Comparisons between the cycles are made for Design Point (DP) and Off-Design Point (ODP) analyses to emphasise the benefits and drawbacks of each cycle. The paper also talks about future trends which include higher Core Outlet Temperatures in excess of 1000 degrees Celsius and the proposal of a simplified cycle configuration which eliminates the need for the recuperator.


2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Nicolai Neumann ◽  
Arne Berthold ◽  
Frank Haucke ◽  
Dieter Peitsch ◽  
Panagiotis Stathopoulos

Abstract Performance improvements of conventional gas turbines are becoming increasingly difficult and costly to achieve. Pressure gain combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycle. Previous cycle analyses considering turbine cooling methods have shown that the application of pressure gain combustion may require more turbine cooling air. This has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsed impingement jets inside the turbine blades. In the first part of this paper, results of pulsed impingement cooling experiments on a curved plate are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is quantified. The second part of this paper presents a gas turbine cycle analysis where the improved cooling approach is incorporated in the cooling air calculation. The effect of pulsed impingement cooling on the overall cycle efficiency is shown for both Joule and PGC cycles. In contrast to the authors’ anticipation, the results suggest that for relevant thermodynamic cycles pulsed impingement cooling increases the thermal efficiency of Joule cycles more significantly than it does in the case of PGC cycles. Thermal efficiency improvements of 1.0 p.p. for pure convective cooling and 0.5 p.p. for combined convective and film with TBC are observed for Joule cycles. But just up to 0.5 p.p. for pure convective cooling and 0.3 p.p. for combined convective and film cooling with TBC are recorded for PGC cycles.


Author(s):  
James Spelling ◽  
Björn Laumert ◽  
Torsten Fransson

A dynamic simulation model of a hybrid solar gas-turbine power plant has been developed, allowing determination of its thermodynamic and economic performance. In order to examine optimum gas-turbine designs for hybrid solar power plants, multi-objective thermoeconomic analysis has been performed, with two conflicting objectives: minimum levelized electricity costs and minimum specific CO2 emissions. Optimum cycle conditions: pressure-ratio, receiver temperature, turbine inlet temperature and flow rate, have been identified for a 15 MWe gas-turbine under different degrees of solarization. At moderate solar shares, the hybrid solar gas-turbine concept was shown to provide significant water and CO2 savings with only a minor increase in the levelized electricity cost.


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