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

Author(s):  
Charalampos Andreades ◽  
Lindsay Dempsey ◽  
Per F. Peterson

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.

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].


2013 ◽  
Author(s):  
Norma J. Kuehn ◽  
Kajal Mukherjee ◽  
Paul Phiambolis ◽  
Lora L. Pinkerton ◽  
Elsy Varghese ◽  
...  

2000 ◽  
Vol 124 (1) ◽  
pp. 89-95 ◽  
Author(s):  
G. Lozza ◽  
P. Chiesa

This paper discusses novel schemes of combined cycle, where natural gas is chemically treated to remove carbon, rather than being directly used as fuel. Carbon conversion to CO2 is achieved before gas turbine combustion. The first part of the paper discussed plant configurations based on natural gas partial oxidation to produce carbon monoxide, converted to carbon dioxide by shift reaction and therefore separated from the fuel gas. The second part will address methane reforming as a starting reaction to achieve the same goal. Plant configuration and performance differs from the previous case because reforming is endothermic and requires high temperature heat and low operating pressure to obtain an elevated carbon conversion. The performance estimation shows that the reformer configuration has a lower efficiency and power output than the systems addressed in Part I. To improve the results, a reheat gas turbine can be used, with different characteristics from commercial machines. The thermodynamic efficiency of the systems of the two papers is compared by an exergetic analysis. The economic performance of natural gas fired power plants including CO2 sequestration is therefore addressed, finding a superiority of the partial oxidation system with chemical absorption. The additional cost of the kWh, due to the ability of CO2 capturing, can be estimated at about 13–14 mill$/kWh.


Author(s):  
Vikram Muralidharan ◽  
Matthieu Vierling

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.


Author(s):  
Juan Pablo Gutierrez ◽  
Terry B. Sullivan ◽  
Gerald J. Feller

The increase in price of natural gas and the need for a cleaner technology to generate electricity has motivated the power industry to move towards Integrated Gasification Combined Cycle (IGCC) plants. The system uses a low heating value fuel such as coal or biomass that is gasified to produce a mixture of hydrogen and carbon monoxide. The potential for efficiency improvement and the decrease in emissions resulting from this process compared to coal-fired power plants are strong evidence to the argument that IGCC technology will be a key player in the future of power generation. In addition to new IGCC plants, and as a result of new emissions regulations, industry is looking at possibilities for retrofitting existing natural gas plants. This paper studies the feasibility of retrofitting existing gas turbines of Natural Gas Combined Cycle (NGCC) power plants to burn syngas, with a focus on the water/steam cycle design limitations and necessary changes. It shows how the gasification island processes can be treated independently and then integrated with the power block to make retrofitting possible. This paper provides a starting point to incorporate the gasification technology to current natural gas plants with minor redesigns.


2019 ◽  
Vol 12 (7) ◽  
pp. 2161-2173 ◽  
Author(s):  
Rebecca L. Siegelman ◽  
Phillip J. Milner ◽  
Eugene J. Kim ◽  
Simon C. Weston ◽  
Jeffrey R. Long

As natural gas supplies a growing share of global primary energy, new research efforts are needed to develop adsorbents for carbon capture from gas-fired power plants alongside efforts targeting emissions from coal-fired plants.


Author(s):  
S. A. Lawson ◽  
D. L. Straub ◽  
S. Beer ◽  
K. H. Casleton ◽  
T. Sidwell

The energy requirements associated with recovering greenhouse gases from Integrated Gasification Combined Cycle (IGCC) or Natural Gas Combined Cycle (NGCC) power plants are significant. The subsequent reductions in overall plant efficiency also result in a higher cost of electricity. In order to meet the future demand for cleaner energy production, this research is focused on improving gas turbine efficiency through advancements in gas turbine cooling capabilities. For this study, an experimental approach was developed to quantify overall effectiveness and net heat flux reduction for a film-cooled test article at high temperature and pressure conditions. A major part of this study focused on validating an advanced optical thermography technique capable of distinguishing between emitted and reflected radiation from film-cooled test articles exposed to exhaust gases in excess of 1000°C and 5 bar. The optical thermography method was used to acquire temperature maps of both external and internal wall temperatures on a test article with fan-shaped film cooling holes. The overall effectiveness and heat flux were quantified with one experiment. The optical temperature measurement technique was capable of measuring wall temperatures to within ±7.2°C. Uncertainty estimates showed that the methods developed for this study were capable of quantifying improvements in overall effectiveness necessary to meet DOE program goals. Results showed that overall effectiveness increased with an increase in blowing ratio and a decrease in mainstream gas pressure while heat flux contours indicated consistent trends.


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