Study on Primary and Secondary Heat-Transport Systems for Sodium-Cooled Fast Reactor

2013 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Igor Pioro ◽  
Glenn Harvel ◽  
Brian Ikeda
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Heat Transport ◽  
Fast Reactor ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Power Conversion ◽  
Gas Turbine Cycle ◽  
Steam Cycle

One of the current engineering challenges is to design next generation (Generation IV) Nuclear Power Plants (NPPs) with significantly higher thermal efficiencies (43–55%) compared to those of current NPPs to match or at least to be close to the thermal efficiencies reached at fossil-fired power plants (55–62%). The Sodium-cooled Fast Reactor (SFR) is one of the six concepts considered under the Generation IV International Forum (GIF) initiative. The BN-600 reactor is a sodium-cooled fast-breeder reactor built at the Beloyarsk NPP in Russia. This concept is the only one from the Generation IV nuclear-power reactors, which is actually in operation (since 1980’s). At the secondary side, it uses a subcritical-pressure Rankine-steam cycle with heat regeneration. The reactor generates electrical power in the amount of 600 MWel. The reactor core dimensions are 0.75 m (height) by 2.06 m (diameter). The UO2 fuel enriched to 17–26% is utilized in the core. There are 2 loops (circuits) for sodium flow. For safety reasons, sodium is used both in the primary and the intermediate circuits. Therefore, a sodium-to-sodium heat exchanger is used to transfer heat from the primary loop to the intermediate one. In this work major parameters of the reactor are listed. The actual scheme of the power-conversion heat-transport system is presented; and the results of the calculation of thermal efficiency of this scheme are analyzed. Details of the heat-transport system, including parameters of the sodium-to-sodium heat exchanger and main coolant pump, are presented. In this paper two possibilities for the SFR in terms of the power-conversion cycle are investigated: 1. a subcritical-pressure Rankine-steam cycle through a heat exchanger (current approach in Russian and Japanese power reactors); 2. a supercritical-pressure CO2 Brayton gas-turbine cycle through a heat exchanger (US approach). With the advent of modern super-alloys, the Rankine-steam cycle has progressed into the supercritical region of the coolant and is generating thermal efficiencies into the mid 50% range. Therefore, the thermal efficiency of a supercritical Rankine-steam cycle is also briefly discussed in this paper. According to GIF, the Brayton gas-turbine cycle is under consideration for future nuclear power reactors. The supercritical-CO2 cycle is a new approach in the Brayton gas-turbine cycle. Therefore, dependence of the thermal efficiency of this SC CO2 cycle on inlet parameters of the gas turbine is also investigated.

A Feasibility Study on Various Power-Conversion Cycles for a Sodium-Cooled Fast Reactor

2012 ◽  
Author(s):  
Alexey Dragunov ◽  
Eugene Saltanov ◽  
Sergey Bedenko ◽  
Igor Pioro
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Nuclear Power ◽  
Power Plants ◽  
Supercritical Pressure ◽  
New Approach ◽  
Heat Regeneration ◽  
Gas Turbine Cycle ◽  
Steam Cycle

One of the current engineering challenges is to design next generation (Generation IV) Nuclear Power Plants (NPPs) with significantly higher thermal efficiencies compared to those of current NPPs to match or at least to be close to thermal efficiencies reached at thermal power plants (43–55%). A Sodium-cooled Fast Reactor (SFR) is one of six concepts considered under the Generation IV International Forum (GIF). This concept is the only one from the Generation IV reactors, which is actually in operation in Russia. In general, there are 3 possibilities for an SFR in terms of the secondary cycle: 1. Subcritical-pressure Rankine-“steam”-cycle through a heat exchanger (current approach used in Russian and Japanese power reactors). 2. Supercritical-pressure Rankine-“steam”-cycle through a heat exchanger (new approach). 3. Supercritical-pressure CO2 Brayton-gas-turbine-cycle through a heat exchanger (US approach). The BN-600 reactor is a sodium-cooled fast-breeder reactor built at the Beloyarsk NPP in Russia. It has been in operation since 1980 and adopts the secondary subcritical-pressure Rankine-“steam”-cycle with heat regeneration. Steam extractions are taken from High-Pressure (HP), Intermediate-Pressure (IP) and Low-Pressure (LP) turbines. The basic method of increasing the thermal efficiency of power plants is to improve it by increasing the operating pressure and temperature. With the advent of modern super alloys, the Rankine-“steam”-cycle has progressed into the supercritical region of the coolant and is generating net efficiencies into the mid 40% range. Calculations of thermal efficiency of a secondary sub- and supercritical-pressure Rankine-“steam”-cycle with heat regeneration are presented in the paper. The Brayton-gas-turbine cycle is under consideration for future nuclear power reactors. The higher operating temperatures will be achieved, the higher thermal efficiency will be. Supercritical CO2 cycle is a new approach in Brayton-gas-turbine cycle. Carbon dioxide has a critical pressure of 7.38 MPa and a critical temperature of 31.0°C, which is significantly less than that of water (22.064 MPa and 373.95°C). However, liquid sodium is more compatible with SC CO2 than with water. Therefore, thermal efficiency of this SC CO2 cycle is also calculated.

scholarly journals Improving the maneuverability and thermal efficiency of modern cogeneration systems based on gas turbine power plants

2022 ◽  
Vol 2150 (1) ◽  
pp. 012020
Author(s):  
E M Lisin ◽  
V O Kindra
Keyword(s):  
Heat Exchanger ◽  
Electric Power ◽  
Gas Turbine ◽  
Thermal Efficiency ◽  
Electricity Generation ◽  
Power Plants ◽  
Heating Period ◽  
Electrical Efficiency ◽  
Network Water ◽  
Calculation Results

Abstract The paper is devoted to the issue of increasing the maneuverability and efficiency of modern cogeneration systems based on gas turbine power plants. Promising solutions for increasing the maneuverability of GTU-CHPP by using heat accumulators and the formation of a preheating circuit of the network water are considered. It is shown that in the non-heating period, it is possible to increase both the thermal efficiency and the generated electric power by installing a heat exchanger in front of the compressor. The calculation results show that this provides an increase of 0.4% in the net electrical efficiency by and an increase 3.3% in the annual electricity generation.

scholarly journals Performance Analyses and Evaluation of Co2 and N2 as Coolants in a Recuperated Brayton Gas Turbine Cycle for a Generation IV Nuclear Reactor Power Plant

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Emmanuel O. Osigwe ◽  
Arnold Gad-Briggs ◽  
Theoklis Nikolaidis ◽  
Pericles Pilidis ◽  
Suresh Sampath
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Critical Conditions ◽  
Working Fluid ◽  
Closed Cycle ◽  
Gas Turbine Cycle

Abstract As demands for clean and sustainable energy renew interests in nuclear power to meet future energy demands, generation IV nuclear reactors are seen as having the potential to provide the improvements required for nuclear power generation. However, for their benefits to be fully realized, it is important to explore the performance of the reactors when coupled to different configurations of closed-cycle gas turbine power conversion systems. The configurations provide variation in performance due to different working fluids over a range of operating pressures and temperatures. The objective of this paper is to undertake analyses at the design and off-design conditions in combination with a recuperated closed-cycle gas turbine and comparing the influence of carbon dioxide and nitrogen as the working fluid in the cycle. The analysis is demonstrated using an in-house tool, which was developed by the authors. The results show that the choice of working fluid controls the range of cycle operating pressures, temperatures, and overall performance of the power plant due to the thermodynamic and heat properties of the fluids. The performance results favored the nitrogen working fluid over CO2 due to the behavior CO2 below its critical conditions. The analyses intend to aid the development of cycles for generation IV nuclear power plants (NPPs) specifically gas-cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs).

A Reevaluation of the Holzwarth Gas Turbine Cycle for Use in Small Power Plants

2001 ◽  
Author(s):  
Osvaldo José Venturini ◽  
Sebastião Varella
Keyword(s):  
Gas Turbine ◽  
Temperature Variation ◽  
Thermal Efficiency ◽  
Power Plants ◽  
Constant Pressure ◽  
Specific Work ◽  
Brayton Cycle ◽  
Small Power ◽  
The One ◽  
Gas Turbine Cycle

The purpose of this work is to analyze a gas turbine working under a cycle similar to the one proposed, by the Dr. Holtzwarth, at the beginning of the last century, showing its potentiality, mainly when applied to small power turbines. The method for analysis is based in the quasi-steady thermodynamic equilibrium principle, where the effects of the pressure and temperature variation, due to the intermittent combustion, are considered. Conclusions are presented considering the increase of the thermal efficiency and the available specific work, resulting from the constant volume combustion, when compared with those of a turbine operating under constant pressure combustion (Brayton Cycle). These results are obtained using actual curves of operation for the compressor and the turbine and, as well as, the “matching” of them.

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.

Reheat Air-Brayton Combined Cycle Power Conversion Off-Nominal and Transient Performance

2014 ◽  
Vol 136 (7) ◽  
Author(s):  
Charalampos Andreades ◽  
Lindsay Dempsey ◽  
Per F. Peterson
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Nuclear Power ◽  
Power Plants ◽  
Power Conversion ◽  
Companion Paper ◽  
Combined Cycle ◽  
Natural Gas Combined Cycle ◽  
Reference Design ◽  
Molten Fluoride

Because molten fluoride salts can deliver heat at temperatures above 600 °C, they can be used to couple nuclear and concentrating solar power heat sources to reheat air combined cycles (RACC). With the open-air configuration used in RACC power conversion, the ability to also inject natural gas or other fuel to boost power at times of high demand provides the electric grid with contingency and flexible capacity while also increasing revenues for the operator. This combination provides several distinct benefits over conventional stand-alone nuclear power plants and natural gas combined cycle and peaking plants. A companion paper discusses the necessary modifications and issues for coupling an external heat source to a conventional gas turbine and provides two baseline designs (derived from the GE 7FB and Alstom GT24). This paper discusses off-nominal operation, transient response, and start-up and shutdown using the GE 7FB gas turbine as the reference design.

Application of Specific Entropy Generation to Enhance Thermal Efficiency of a Combined Cycle

2018 ◽  
Author(s):  
Yousef Haseli
Keyword(s):  
Heat Exchanger ◽  
Power Plant ◽  
Gas Turbine ◽  
Entropy Generation ◽  
Thermal Efficiency ◽  
Combined Cycle ◽  
Flue Gases ◽  
Specific Entropy ◽  
Topping Cycle ◽  
Gas Turbine Cycle

The method of specific entropy generation (SEG) is employed to show how the thermal efficiency of a combined cycle power plant can be improved. SEG is defined as the total entropy generation rate associated with the operation of a power plant per unit flowrate of the fuel burnt in the combustor. In a recent article published in Journal of Energy Resources and Technology, it is shown that the thermal efficiency of a gas turbine cycle inversely correlates with SEG. In this work, we extend the analysis to show that the same relation between the thermal efficiency and SEG is also valid for a combined cycle. The topping cycle consists of a compressor, a combustor and a gas turbine, whereas the bottoming cycle includes a heat recovery steam generator, a steam turbine, a condenser, a deaerator, a condensate pump and a feed water pump. It is shown that the minimization of SEG is identical to the maximization of thermal efficiency. An illustrative example is presented using the SEG method to improve the efficiency of the combined cycle. The results reveal that 89% of the inefficiencies takes place in the gas turbine cycle. A modified design is then proposed to reduce the efficiency losses in the topping cycle. In the modified design, the thermal energy of the flue gases is first used in a heat exchanger to preheat the air before the combustor. The flue gases leaving the heat exchanger is then directed to the HRSG for producing steam. With this modification, the thermal efficiency and the power output of the combined cycle increase 2.7 percentage points and 20.9 kW per unit molar flowrate of the fuel. Recovering the thermal energy of the flue gases for both preheating the air and producing the steam appears to be more efficient than just producing the steam. Despite the net power production of the bottoming cycle decreases in the modified design, the overall efficiency of the combined cycle increases due to the improvement in the efficiency of the topping cycle.

scholarly journals Energetic and Exergetic Investigation of Regenerative Gas Turbine Air-Bottoming/Steam -Bottoming Combined Cycle

Mechanika ◽  
2021 ◽  
Vol 27 (3) ◽  
pp. 251-258
Author(s):  
Mohammad Nadeem KHAN
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Fuel Consumption ◽  
Thermal Efficiency ◽  
Combined Cycle ◽  
Specific Fuel Consumption ◽  
Exergy Loss ◽  
Exhaust Gases ◽  
Topping Cycle ◽  
Gas Turbine Cycle

The present study is a thermodynamic analysis of a Regenerative Air-Bottoming combined (RABC) cycle /Steam bottoming combined (RABC) cycle operated by the exhaust gases the topping gas turbine cycle. The fractional mass of exhaust gases passes through the first heat exchanger where it exchanges heat with the compressed air from the air compressor of topping cycle and remaining amount of exhaust gasses passes through a second heat exchanger where it uses to supply heat to RABC cycle or third heat exchanger where it uses to supply heat to RSBC cycle. The energetic and exergetic performance of RABC cycle and RSBC cycle is investigated using turbine inlet temperature (1000 K⩽ TIT⩽1500 K) and mass fraction of exhaust gas (0⩽x⩽1) of the topping cycle as the input variables.  The work net output attained its peak value at x=0 which is 22.1 % to 27.3 % for RABC cycle and 22.7 % to 21.5 % for RSBC cycle whereas the maximum thermal efficiency and minimum specific fuel consumption is observed at x=1. Also exergy loss by exhaust gases is minimum at x=0 for both RABC cycle and RSBC cycle. Finally, it is concluded that for the maximum work net output and minimum exergy loss by exhaust gases, RABC cycle is the best option followed by RSBC cycle but for optimum thermal efficiency and minimum specific fuel consumption purely regenerative gas turbine cycle have no comparison with RABC cycle and RSBC cycle.

Assessing the Potential of Gas-Recuperation in Reheated Gas Turbines Within Combined Gas-Steam Power Plants

2014 ◽  
Author(s):  
Adam Doligalski ◽  
Luis Sanchez de Leon ◽  
Pavlos K. Zachos ◽  
Vassilios Pachidis
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Power Plants ◽  
Current Approach ◽  
Combined Cycle ◽  
Variable Position ◽  
Power Turbine ◽  
Power Generation Systems ◽  
Gas Turbine Cycle

This paper presents a comparative analysis between two different gas turbine configurations for implementation within combined cycle power plants, aiming to downselect the most promising one in terms of thermal efficiency at design point. The analysed gas turbines both feature the same dual-pressure steam bottoming cycle, but differ in the gas turbine cycle itself: the first configuration comprises a single-shaft reheated gas turbine with variable position of the reheater (representative of the current approach of the industry to combined cycle power plants), whilst the second configuration comprises a dual-shaft reheated-recuperated engine with free power turbine. Comparison of the two competing gas turbine configurations is conducted by means of systematic exploration of the combined cycle design space. The analysis showed that the reheated-recuperated configuration delivers higher thermal efficiency than the more conventional reheated (non-recuperated) gas turbine and is identified, therefore, as a competitive option for future combined cycle power generation systems.

Analysis of a Combined Cycle Plant Using a Small Particle Receiver to Drive a Primary Brayton Cycle

2015 ◽  
Author(s):  
Matthew Miguel Virgen ◽  
Fletcher Miller
Keyword(s):  
Heat Exchanger ◽  
Gas Turbine ◽  
Small Particle ◽  
Power Plants ◽  
Rankine Cycle ◽  
Combined Cycle ◽  
Working Fluid ◽  
Brayton Cycle ◽  
Efficiency Gains ◽  
Steam Cycle

All current commercial CSP plants operate at relatively low thermodynamic efficiency due to lower temperatures than similar conventional plants and due to the fact that they all employ Rankine conversion cycles. We present here an investigation on the effects of adding a bottoming steam power cycle to a hybrid CSP plant based on a Small Particle Heat Exchange Receiver (SPHER) driving a gas turbine as the primary cycle. Due to the high operating temperature of the SPHER being considered (over 1000 Celsius), the exhaust air from the primary Brayton cycle still contains a tremendous amount of exergy. While in the previous analysis this fluid was only used in a recuperator to preheat the Brayton working fluid, the current analysis explores the potential power and efficiency gains from instead directing the exhaust fluid through a heat exchanger to power a Rankine steam cycle. Not only do we expect the efficiency of this model to be competitive with conventional power plants, but the water consumption per kilowatt-hour will also be reduced by nearly two thirds as compared to most existing concentrating solar thermal power plants as a benefit of having air as the primary working fluid, which eliminates the condensation step present in Rankine-cycle systems. Coupling a new steam cycle model with the gas-turbine CSP model previously developed at SDSU, a wide range of cases were run to explore options for maximizing both power and efficiency from the proposed CSP combined cycle gas turbine (CCGT) plant. Due to the generalized nature of the bottoming cycle modeling, and the varying nature of solar power, special consideration had to be given to the behavior of the heat exchanger and Rankine cycle in off-design scenarios. The trade-offs of removing the recuperator for preheating the primary fluid are compared to potential overall power and efficiency gains in the combined cycle case.

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