Closed-cycle gas turbine

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Closed-cycle gas turbine schematic

C compressor and T turbine assembly
w high-temperature heat exchanger
ʍ low-temperature heat exchanger
~ mechanical load, e.g. electric generator

A closed-cycle gas turbine is a turbine that uses a gas (e.g. air, nitrogen, helium, argon,[1][2] etc.) for the working fluid as part of a closed thermodynamic system. Heat is supplied from an external source.[3] Such recirculating turbines follow the Brayton cycle.[4][5]

Background[edit]

The initial patent for a closed-cycle gas turbine (CCGT) was issued in 1935 and they were first used commercially in 1939.[3] Seven CCGT units were built in Switzerland and Germany by 1978.[2] Historically, CCGTs found most use as external combustion engines "with fuels such as bituminous coal, brown coal and blast furnace gas" but were superseded by open cycle gas turbines using clean-burning fuels (e.g. "gas or light oil"), especially in highly efficient combined cycle systems.[3] Air-based CCGT systems have demonstrated very high availability and reliability.[6] The most notable helium-based system thus far was Oberhausen 2, a 50 megawatt cogeneration plant that operated from 1975 to 1987 in Germany.[7] Compared to Europe where the technology was originally developed, CCGT is not well known in the US.[8]

Nuclear power[edit]

Gas-cooled reactors powering helium-based closed-cycle gas turbines were suggested in 1945.[8] The experimental ML-1 nuclear reactor in the early-1960s used a nitrogen-based CCGT operating at 0.9 MPa.[9] The cancelled pebble bed modular reactor was intended to be coupled with a helium CCGT.[10] Future nuclear (Generation IV reactors) may employ CCGT for power generation,[3] e.g. Flibe Energy intends to produce a liquid fluoride thorium reactor coupled with a CCGT.[11]

Development[edit]

Closed-cycle gas turbines hold promise for use with future high temperature solar power[3] and fusion power[2] generation.

They have also been proposed as a technology for use in long-term space exploration.[12]

Supercritical carbon dioxide closed-cycle gas turbines are under development; "The main advantage of the supercritical CO2 cycle is comparable efficiency with the helium Brayton cycle at significantly lower temperature" (550 °C vs. 850 °C), but with the disadvantage of higher pressure (20 MPa vs. 8 MPa).[13] Sandia National Laboratories has a goal of developing a 10 MWe supercritical CO2 demonstration CCGT by 2019.[14]

See also[edit]

References[edit]

  1. ^ Nitrogen or Air Versus Helium for Nuclear Closed Cycle Gas Turbines | Atomic Insights
  2. ^ a b c AN ASSESSMENT OF THE BRAYTON CYCLE FOR HIGH PERFORMANCE POWER PLANTS
  3. ^ a b c d e Frutschi, Hans Ulrich (2005). Closed-Cycle Gas Turbines. ASME Press. ISBN 0-7918-0226-4. Archived from the original on 21 December 2011. Retrieved 7 December 2011. Note: front matter (including preface and introduction; PDF link) is open access.
  4. ^ Thermodynamics and Propulsion: Brayton Cycle
  5. ^ A REVIEW OF HELIUM GAS TURBINE TECHNOLOGY FOR HIGH-TEMPERATURE GAS-COOLED REACTORS Archived 26 April 2012 at the Wayback Machine
  6. ^ Keller, C. (1978). "Forty years of experience on closed-cycle gas turbines". Annals of Nuclear Energy. 5 (8–10): 405–422. doi:10.1016/0306-4549(78)90021-X.
  7. ^ "Nuclear Power: Small modular reactors". Power Engineering. 7 June 2012. Retrieved 7 June 2012.
  8. ^ a b McDonald, C. F. (2012). "Helium turbomachinery operating experience from gas turbine power plants and test facilities". Applied Thermal Engineering. 44: 108–181. doi:10.1016/j.applthermaleng.2012.02.041.
  9. ^ "ML-1 Mobile Power System: Reactor in a Box | Atomic Insights". Archived from the original on 22 July 2012. Retrieved 6 June 2012.
  10. ^ IAEA Technical Committee Meeting on "Gas Turbine Power Conversion Systems for Modular HTGRs"[permanent dead link], held from 14–16 November 2000 in Palo Alto, California. International Atomic Energy Agency, Vienna (Austria). Technical Working Group on Gas-Cooled Reactors. IAEA-TECDOC--1238, pp:102-113[permanent dead link]
  11. ^ Introduction to Flibe Energy: YouTube Video (~20 min) and PDF of slides used
  12. ^ Introduction to Gas Turbines for Non-Engineers (see page 5)
  13. ^ V. Dostal, M.J. Driscoll, P. Hejzlar, "Archived copy" (PDF). Archived from the original (PDF) on 27 December 2010. Retrieved 7 December 2011.CS1 maint: Archived copy as title (link) MIT-ANP-Series, MIT-ANP-TR-100 (2004)
  14. ^ Sandia National Laboratories: Supercritical CO2-Brayton Cycle

External links[edit]