Optimized Performance and Cost Potential for Indirect Supercritical CO2 Coal Fired Power Plants

2021 ◽  
Author(s):  
Sandeep R. Pidaparti ◽  
Charles W. White ◽  
Nathan T. Weiland
Keyword(s):  
Supercritical Co2 ◽  
Power Plants ◽  
Higher Plant ◽  
Levelized Cost Of Electricity ◽  
Power Cycles ◽  
Power Cycle ◽  
Percentage Points ◽  
Design Variables ◽  
Recompression Cycle ◽  
Plant Efficiency

Abstract Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat etc. Therefore, understanding their performance and cost potential is important for commercialization of the technology. This study presents the techno-economic global optimization results of coal-fired utility scale power plants based on indirect sCO2 power cycles with and without carbon capture and storage (CCS). Four power cycle configurations are considered for optimization – recompression cycle (RC) with and without turbine reheat and partial cooling cycle (PCC) with and without turbine reheat. Several design variables are identified for each power cycle configuration and these design variables are optimized to minimize the levelized cost of electricity (LCOE) for each plant. The optimization design variables included parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperator approach temperatures and pressure drops etc. The optimization is conducted using automated derivative free optimization algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform. For sCO2 power plants both with and without CCS, recompression cycle with reheat (RC with reheat) has the highest plant efficiency and lowest LCOE among the considered power cycle configurations. For plants with CCS, the RC with reheat configuration offered 8 percentage points higher plant efficiency (HHV basis) and 14.6% lower LCOE compared to a state-of-the-art (SOA) PC-fired supercritical steam Rankine plant with CCS. For plants without CCS, the RC with reheat configuration offered 4.7 percentage points higher plant efficiency and 7% lower LCOE compared to a SOA PC-fired supercritical steam Rankine plant without CCS.

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.

Control of a Supercritical CO2 Recompression Brayton Cycle Demonstration Loop

2013 ◽  
Author(s):  
T. Conboy ◽  
J. Pasch ◽  
D. Fleming
Keyword(s):  
Supercritical Co2 ◽  
High Efficiency ◽  
Power Conversion ◽  
Department Of Energy ◽  
Test Facility ◽  
Attractive Alternative ◽  
Commercial Development ◽  
Power Cycle ◽  
Test Loop ◽  
Recompression Cycle

The US Department of Energy is currently focused on the development of next-generation nuclear power reactors, with an eye towards improved efficiency and reduced capital cost. To this end, reactors using a closed-Brayton power conversion cycle have been proposed as an attractive alternative to steam turbines. The supercritical-CO2 recompression cycle has been identified as a leading candidate for this application as it can achieve high efficiency at relatively low operating temperatures with extremely compact turbomachinery. Sandia National Laboratories has been a leader in hardware and component development for the supercritical-CO2 cycle. With contractor Barber-Nichols Inc, Sandia has constructed a megawatt-class S-CO2 cycle test-loop to investigate the key areas of technological uncertainty for this power cycle, and to confirm model estimates of advantageous thermodynamic performance. Until recently, much of the work has centered on the simple S-CO2 cycle — a recuperated Brayton loop with a single turbine and compressor. However work has recently progressed to a recompression cycle with split-shaft turbo-alternator-compressors, unlocking the potential for much greater efficiency power conversion, but introducing greater complexity in control operations. The following sections use testing experience to frame control actions made by test loop operators in bringing the recompression cycle from cold startup conditions through transition to power generation on both turbines, to the desired test conditions, and finally to a safe shutdown. During this process, considerations regarding turbocompressor thrust state, CO2 thermodynamic state at the compressor inlet, compressor surge and stall, turbine u/c ratio, and numerous other factors must be taken into account. The development of these procedures on the Sandia test facility has greatly reduced the risk to industry in commercial development of the S-CO2 power cycle.

A Comparison Study for Off-Design Performance Prediction of a Supercritical CO2 Compressor With Similitude Analysis

2019 ◽  
Author(s):  
Yongju Jeong ◽  
Seongmin Son ◽  
Seong kuk Cho ◽  
Seungjoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
Critical Point ◽  
Supercritical Co2 ◽  
Power Plants ◽  
Cycle Performance ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Power Cycle ◽  
Design Performance ◽  
Wide Range ◽  
Phase Fluid

Abstract Most of the power plants operating nowadays mainly have adopted a steam Rankine cycle or a gas Brayton cycle. To devise a better power conversion cycle, various approaches were taken by researchers and one of the examples is an S-CO2 (supercritical CO2) power cycle. Over the past decades, the S-CO2 power cycle was invented and studied. Eventually the cycle was successful for attracting attentions from a wide range of applications. Basically, an S-CO2 power cycle is a variation of a gas Brayton cycle. In contrast to the fact that an ordinary Brayton cycle operates with a gas phase fluid, the S-CO2 power cycle operates with a supercritical phase fluid, where temperatures and pressures of working fluid are above the critical point. Many advantages of S-CO2 power cycle are rooted from its novel characteristics. Particularly, a compressor in an S-CO2 power cycle operates near the critical point, where the compressibility is greatly reduced. Since the S-CO2 power cycle greatly benefits from the reduced compression work, an S-CO2 compressor prediction under off-design condition has a huge impact on overall cycle performance. When off-design operations of a power cycle are considered, the compressor performance needs to be specified. One of the approaches for a compressor off-design performance evaluation is to use the correction methods based on similitude analysis. However, there are several approaches for deriving the equivalent conditions but none of the approaches has been thoroughly examined for S-CO2 conditions based on data. The purpose of this paper is comparing these correction models to identify the best fitted approach, in order to predict a compressor off-design operation performance more accurately from limited amount of information. Each correction method was applied to two sets of data, SCEIL experiment data and 1D turbomachinery code off-design prediction code generated data, and evaluated in this paper.

Concepts and Experiences for Higher Plant Efficiency With Modern Advanced Boiler and Incineration Technology

2010 ◽  
Author(s):  
Armin Main ◽  
Thomas Maghon
Keyword(s):  
Flue Gas ◽  
Power Plants ◽  
Fossil Fuels ◽  
Live Steam ◽  
Gas Temperature ◽  
Higher Plant ◽  
Advantages And Disadvantages ◽  
Boiler Tubes ◽  
Steam Parameters ◽  
Plant Efficiency

The efforts for reducing CO2 Emissions into atmosphere and increasing costs for fossil fuels concepts are the drivers for Energy from Waste (EfW) facilities with higher plant efficiency. In the past steam parameters for EfW were requested mainly at 40 bars and 400 °C (580 psi and 752 F). In case of coal fired power plants at the same location as the EfW facilities higher steam parameters at 90 bar, 520 °C (1305 psi, 968 F) have been used for the design of stoker and boiler. This long-term experience with higher steam parameters is the platform for the todays and future demand in higher plant efficiency. Increase in EfW plant efficiency is achievable by increasing temperature and pressure of live steam going along with optimized combustion conditions when using well proven grate technology for waste incineration. On the other hand higher steam parameters result in higher corrosion rates on the boiler tubes and the optimization of the combustion conditions are limited by the burn out quality requirements of slag and flue gas. Advantages and disadvantages have therefore to be balanced carefully. This paper will present different measures for optimized boiler and combustion conditions compared to an EfW plant with live steam at 40 bars and 400 °C (580 psi and 752 F) and 60% excess of combustion air. Plants operated at these conditions have very low maintenance costs created by corrosion of boiler tubes and show performance with very high availability. The following parameters and experiences will be evaluated: - reduction of excess air; - flue gas temperature at boiler outlet; - higher steam parameters (pressure and temperature); - heating surfaces for steam superheating in the radiation boiler section; - steam reheating; - external superheaters using auxiliary fuels. The comparison of the different methods for increasing the efficiency together with resulting technology challenges incorporates the experiences from modern EfW reference facilities built in Naples/Italy, Ruedersdorf (Berlin)/Germany and Heringen/Germany.

scholarly journals Corrosion and Erosion Behavior in Supercritical CO2 Power Cycles

2014 ◽  
Author(s):  
Darryn Fleming ◽  
Alan Kruizenga ◽  
James Pasch ◽  
Tom Conboy ◽  
Matt Carlson
Keyword(s):  
Carbon Dioxide ◽  
Stainless Steel ◽  
Intergranular Corrosion ◽  
Supercritical Co2 ◽  
Power Production ◽  
Operating Conditions ◽  
Working Fluid ◽  
Power Cycles ◽  
Power Cycle ◽  
Potential Issue

Supercritical Carbon Dioxide (S-CO2) is emerging as a potential working fluid in power-production Brayton cycles. As a result, concerns have been raised regarding fluid purity within the power cycle loops. Additionally, investigations into the longevity of the S-CO2 power cycle materials are being conducted to quantify the advantages of using S-CO2 versus other fluids, since S-CO2 promises substantially higher efficiencies. One potential issue with S-CO2 systems is intergranular corrosion [1]. At this time, Sandia National Laboratories (SNL) is establishing a materials baseline through the analysis of 1) “as received” stainless steel piping, and 2) piping exposed to S-CO2 under typical operating conditions with SNL’s Brayton systems. Results from ongoing investigations are presented. A second issue that SNL has discovered involves substantial erosion in the turbine blade and inlet nozzle. It is believed that this is caused by small particulates that originate from different materials around the loop that are entrained by the S-CO2 to the nozzle, where they impact the inlet nozzle vanes, causing erosion. We believe that, in some way, this is linked to the purity of the S-CO2, the corrosion contaminants, and the metal particulates that are present in the loop and its components.

S-Ethane Brayton Power Conversion Systems for Concentrated Solar Power Plant

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Luis Coco Enríquez ◽  
Javier Muñoz-Antón ◽  
José María Martínez-Val Peñalosa
Keyword(s):  
Power Plants ◽  
Solar Power ◽  
Subcritical Water ◽  
Plant Performance ◽  
Solar Collectors ◽  
Steam Generation ◽  
Concentrated Solar Power ◽  
Power Cycles ◽  
Solar Power Plants ◽  
Recompression Cycle

The objective of this investigation is the comparison between supercritical ethane (s-ethane, C2H6) and supercritical carbon dioxide (s-CO2) Brayton power cycles for line-focusing concentrated solar power plants (CSP). In this study, CSP are analyzed with linear solar collectors (parabolic trough (PTC) or linear Fresnel (LF)), direct molten salt (MS), or direct steam generation (DSG) as heat transfer fluids (HTF), and four supercritical Brayton power cycles configurations: simple Brayton cycle (SB), recompression cycle (RC), partial cooling with recompression cycle (PCRC), and recompression with main compression intercooling cycle (RCMCI). All Brayton power cycles were assessed with two working fluids: s-CO2 and s-ethane. As a main result, we confirmed that s-ethane Brayton power cycles provide better net plant performance than s-CO2 cycles for turbine inlet temperatures (TITs) from 300 °C to 550 °C. As an example, the s-ethane RCMCI plant configuration net efficiency is ∼42.11% for TIT = 400 °C, and with s-CO2 the plant performance is ∼40%. The CSP Brayton power plants were also compared with another state-of-the-art CSP with DSG in linear solar collectors and a subcritical water Rankine power cycle with direct reheating (DRH), and a maximum plant performance between ∼40% and 41% (TIT = 550 °C).

Impact of Plant Siting on Performance and Economics of Indirect Supercritical CO2 Coal Fired Power Plants

2021 ◽  
Author(s):  
Sandeep R. Pidaparti ◽  
Charles W. White ◽  
Nathan T. Weiland
Keyword(s):  
Supercritical Co2 ◽  
Optimization Design ◽  
Power Plants ◽  
Waste Heat ◽  
The United States ◽  
Attractive Alternative ◽  
Plant Design ◽  
Power Cycles ◽  
The Impact ◽  
And Storage

Abstract Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat, etc. Due to the near-ambient CO2 critical temperature of 31°C, the effects of ambient temperature on sCO2 power cycles performance are expected to be more significant than for steam Rankine cycles. This study presents the impact of plant siting on the performance and economics of coal-fired utility scale power plants based on indirect sCO2 power cycles with carbon capture and storage (CCS). Four different plant sites across the United States have been selected for investigation: Chicago, IL; Kemmerer, WY; Houston, TX; Knoxville, TN. For each plant site, local parameters such as design ambient conditions, coal type and prices, captured CO2 transportation and storage (T&S) costs are considered for the techno-economic analyses (TEA). To determine the optimum plant design for each location, two power cycle configurations (recompression cycle, partial cooling cycle with reheat) and two cooling technologies (dry and adiabatic cooling) are examined. The optimization was conducted using automated derivative-free optimization (DFO) algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform. The optimization design variables include parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperators approach temperature and pressure drop etc. The study demonstrates the variability in optimal plant design for different ambient and fuel input conditions. The results will be used in future sCO2 technology market analyses.

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.

scholarly journals Solar Desalination Driven by Organic Rankine Cycles (Orc) and Supercritical CO2 Power Cycles: An Update

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 153
Author(s):  
Agustín M. Delgado-Torres ◽  
Lourdes García-Rodríguez
Keyword(s):  
Supercritical Co2 ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Medium Temperature ◽  
Solar Ponds ◽  
Power Cycles ◽  
Power Cycle ◽  
First Case ◽  
Thermal Desalination ◽  
Desalination Technology

In the field of desalination powered by renewable energies, the use of solar power cycles exhibits some favorable characteristics, such as the possibility of implementing thermal energy storage systems or a multi-generation scheme (e.g., electricity, water, cooling, hydrogen). This article presents a review of the latest design proposals in which two power cycles of great potential are considered: the organic Rankine cycle and the supercritical CO2 power cycle, the latter of growing interest in recent years. The designs found in the literature are grouped into three main types of systems. In the case of solar ORC-based systems, the option of reverse osmosis as a desalination technology is considered in medium-temperature solar systems with storage but also with low-temperature using solar ponds. In the first case, it is also common to incorporate single-effect absorption systems for cooling production. The use of thermal desalination processes is also found in many proposals based on solar ORC. In this case, the usual configuration implies the cycle’s cooling by the own desalination process. This option is also common in systems based on the supercritical CO2 power cycle where MED technology is usually selected. Designs proposals are reviewed and assessed to point out design recommendations.

scholarly journals Supercritical CO2 Heat Exchanger Fouling and its Impact on RCBC Efficiency

2018 ◽  
Author(s):  
Darryn Fleming ◽  
Kirsten Norman ◽  
Salvador Rodriguez ◽  
James Pasch ◽  
Matthew Carlson ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Pressure Drop ◽  
Supercritical Co2 ◽  
Critical Factor ◽  
Power Production ◽  
Working Fluid ◽  
Power Cycles ◽  
Power Cycle ◽  
Printed Circuit ◽  
Overall Efficiency

As supercritical carbon dioxide (sCO2) is emerging as a potential working fluid in power production Brayton cycles, fluid purity within the power cycle loops has become an issue impacting commercialization. Sandia National Laboratories has been evaluating the longevity of sCO2 recompression closed Brayton power cycles to quantify the advantages of sCO2 over other fluids as utilizing sCO2 yields comparatively greater efficiencies. Hydrocarbon plugging has been observed in the small printed circuit heat exchanger channels of our high temperature recuperator, increasing pressure drop across the heat exchanger. As pressure drop is a critical factor in the overall efficiency of sCO2 recompression closed Brayton cycles, in this paper we report on our investigation into heat exchanger efficiency reduction from hydrocarbon plugging induced pressure drop.

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