scholarly journals Selected Issues of the Structures and Parameters of Supercritical CO2 Gas Turbine Cycles

2020 ◽  
Vol 22 (2) ◽  
pp. 565-584
Author(s):  
Jarosław Milewski ◽  
Kamil Futyma ◽  
Arkadiusz Szczęśniak ◽  
Marcin Wołowicz ◽  
Gabriel Ziembicki

AbstractThe paper presents a variant analysis of the structures of closed gas turbines using supercritical carbon dioxide (super-CO2) as a working fluid. Several configurations covered in the available literature were collected, commented on and compared. The parameters of the cycles, such as operating temperature and heat supply are noted and commented on. There are three main configurations considered in the available literature: the precompression cycle, partial cooling cycle, and recompression cycle.

Author(s):  
Leonid Moroz ◽  
Petr Pagur ◽  
Oleksii Rudenko ◽  
Maksym Burlaka ◽  
Clement Joly

Bottoming cycles are drawing a real interest in a world where resources are becoming scarcer and the environmental footprint of power plants is becoming more controlled. Reduction of flue gas temperature, power generation boost without burning more fuel and even production of heat for cogeneration applications are very attractive and it becomes necessary to quantify how much can really be extracted from a simple cycle to be converted to a combined configuration. As supercritical CO2 is becoming an emerging working fluid [2, 3, 5, 7 and 8] due not only to the fact that turbomachines are being designed significantly more compact, but also because of the fluid’s high thermal efficiency in cycles, it raises an increased interest in its various applications. Evaluating the option of combined gas and supercritical CO2 cycles for different gas turbine sizes, gas turbine exhaust gas temperatures and configurations of bottoming cycle type becomes an essential step toward creating guidelines for the question, “how much more can I get with what I have?”. Using conceptual design tools for the cycle system generates fast and reliable results to draw this type of conclusion. This paper presents both the qualitative and quantitative advantages of combined cycles for scalability using machines ranging from small to several hundred MW gas turbines to determine which configurations of S-CO2 bottoming cycles are best for pure electricity production.


Author(s):  
Valeriu Vilag ◽  
Jeni Vilag ◽  
Cleopatra Cuciumita

Gas turbines represent energetic machines that operate following the Brayton thermodynamic cycle [6], [16] creating mechanical power and/or thrust. The majority of them use atmospheric air as working fluid but some are working in a closed loop with either air, carbon dioxide or other convenient gas. The main parameters defining the cycle are the combustion temperature and the overall pressure ratio [20]. In principle, the higher the combustion temperature is, the higher the efficiency of the entire gas turbine will be and, for a chosen value of the combustion temperature an optimum overall pressure ratio exists [29]. The main components of the gas turbine are:


2021 ◽  
Author(s):  
M. A. Ancona ◽  
M. Bianchi ◽  
L. Branchini ◽  
A. De Pascale ◽  
F. Melino ◽  
...  

Abstract Gas turbines are often employed in the industrial field, especially for remote generation, typically required by oil and gas production and transport facilities. The huge amount of discharged heat could be profitably recovered in bottoming cycles, producing electric power to help satisfying the onerous on-site energy demand. The present work aims at systematically evaluating thermodynamic performance of ORC and supercritical CO2 energy systems as bottomer cycles of different small/medium size industrial gas turbine models, with different power rating. The Thermoflex software, providing the GT PRO gas turbine library, has been used to model the machines performance. ORC and CO2 systems specifics have been chosen in line with industrial products, experience and technological limits. In the case of pure electric production, the results highlight that the ORC configuration shows the highest plant net electric efficiency. The average increment in the overall net electric efficiency is promising for both the configurations (7 and 11 percentage points, respectively if considering supercritical CO2 or ORC as bottoming solution). Concerning the cogenerative performance, the CO2 system exhibits at the same time higher electric efficiency and thermal efficiency, if compared to ORC system, being equal the installed topper gas turbine model. The ORC scarce performance is due to the high condensing pressure, imposed by the temperature required by the thermal user. CO2 configuration presents instead very good cogenerative performance with thermal efficiency comprehended between 35 % and 46 % and the PES value range between 10 % and 22 %. Finally, analyzing the relationship between capital cost and components size, it is estimated that the ORC configuration could introduce an economical saving with respect to the CO2 configuration.


Author(s):  
Ragnhild E. Ulfsnes ◽  
Olav Bolland ◽  
Kristin Jordal

One of the concepts proposed for capture of CO2 in power production from gaseous fossil fuels is the semi-closed O2/CO2 gas turbine cycle. The semi-closed O2/CO2 gas turbine cycle has a near to stoichiometric combustion with oxygen, producing CO2 and water vapor as the combustion products. The water vapor is condensed and removed from the process, the remaining gas, primarily CO2, is mainly recycled to keep turbine inlet temperature at a permissible level. A model for predicting transient behavior of the semi-closed O2/CO2 gas turbine cycle is presented. The model is implemented in the simulation tool gPROMS (Process System Enterprise Ltd.), and simulations are performed to investigate two different issues. The first issue is to see how different cycle performance variables interact during transient behavior; the second is to investigate how cycle calculations are affected when including the gas constant and the specific heat ratio in compressor characteristics. The simulations show that the near to stoichiometric combustion and the working fluid recycle introduce a high interaction between the different cycle components and variables. This makes it very difficult to analytically predict the cycle performance during a transient event, i.e. simulations are necessary. It is also found that, except for the shaft speed calculation, the introduction of gas constant and specific heat ratio dependence on the compressor performance map will have only a minor influence on the process performance.


1970 ◽  
Author(s):  
Stephen Luchter

Gas-turbine waste heat appears to be a valuable source of energy, yet the number of installations in which this energy is utilized is minimal. The reasons for this are reviewed and a typical nonafterburning cycle is examined for both steam and an “organic” working fluid. The power level range over which each is attractive is obtained, and the costs of each are compared on a relative basis.


Author(s):  
C. F. McDonald ◽  
R. G. Adams ◽  
F. R. Bell ◽  
P. Fortescue

The gas turbine high-temperature gas-cooled reactor (HTGR) power plant combines the existing design HTGR core with a closed-cycle helium gas turbine power conversion system directly in the reactor primary circuit. The high density helium working fluid results in a very compact power conversion system. While the geometries of the helium turbomachinery, heat exchangers, and internal gas flow paths differ from air breathing gas turbines because of the nature of the working fluid and the high degree of pressurization, many of the aerodynamic, heat transfer and dynamic analytical procedures used in the design are identical to conventional open-cycle industrial gas turbine practice. This paper outlines some of the preliminary design considerations for the rotating machinery, heat exchangers, and other major primary system components for an integrated type of plant embodying multiple gas turbine loops. The high potential for further improvement in plant efficiency and capacity, for both advanced dry-cooled and waste heat power cycle versions of the direct-cycle nuclear gas turbine, is also discussed.


Author(s):  
K. K. Botros ◽  
D. Sennhauser ◽  
L. Siarkowski

Concerns about the effects of greenhouse gas emissions on the Earth’s climate have lead to a considerable focus by the public and governments on the levels of emissions that are generated by industrial activities. In Canada, it has been recognized that gas transmission systems are rated second in overall CO2 production in the Natural Gas Industry (next to gas processing). Most of the gas transmission systems are powered by gas turbines at compressor stations resulting in significant CO2 emissions (at the rate of ∼ 6 kilo tonnes/ per MW-year). This can be reduced if the CO2 can be separated from the gas turbine exhaust stream and directed for reuse or sequestration. This paper presents results of techno-thermodynamic assessment of two power cycle adjustments to increase CO2 concentrations in the exhaust gas from turbines. The working fluid in the two semi-closed cycles are made rich in CO2, thus making it easy to capture the CO2 from the flue gas by means of physical absorption techniques rather than by the conventional expensive amine adsorption methods. Additionally, the CO2 rich working fluid is shown to give rise to a higher exhaust gas temperature from the gas turbine semi-closed cycles, allowing a steam bottom cycle to be effective in augmenting the power delivered by the entire system by 50%, hence contributing to reducing emission by increasing the overall thermal efficiency of the system.


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