Closed-cycle gas turbine
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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
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most use as external combustion engines "with fuels such as bituminous coal, brown coal and blast furnace gas" but were superseded by open cycle gas turbines using clean-burning fuels (e.g. "gas or light oil"), especially in highly efficient combined cycle systems.[3] Air-based CCGT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
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
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]
See also
References
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- US Patent 5309492 "Control for a closed cycle gas turbine system"
- Industrial Closed-cycle Gas Turbines for Conventional and Nuclear Fuel (1967)
- Brayton Lab on YouTube (at Sandia National Laboratories, 2014)
- ↑ Nitrogen or Air Versus Helium for Nuclear Closed Cycle Gas Turbines | Atomic Insights
- ↑ 2.0 2.1 2.2 AN ASSESSMENT OF THE BRAYTON CYCLE FOR HIGH PERFORMANCE POWER PLANTS
- ↑ 3.0 3.1 3.2 3.3 3.4 Lua error in package.lua at line 80: module 'strict' not found. Note: front matter (including preface and introduction; PDF link) is open access.
- ↑ Thermodynamics and Propulsion: Brayton Cycle
- ↑ A REVIEW OF HELIUM GAS TURBINE TECHNOLOGY FOR HIGH-TEMPERATURE GAS-COOLED REACTORS
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- ↑ ML-1 Mobile Power System: Reactor in a Box | Atomic Insights
- ↑ IAEA Technical Committee Meeting on "Gas Turbine Power Conversion Systems for Modular HTGRs", 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
- ↑ Introduction to Flibe Energy: YouTube Video (~20 min) and PDF of slides used
- ↑ Introduction to Gas Turbines for Non-Engineers (see page 5)
- ↑ V. Dostal, M.J. Driscoll, P. Hejzlar, A Supercritical Carbon Dioxide Cycle for Next Generation Nuclear Reactors at the Wayback Machine (archived December 27, 2010) MIT-ANP-Series, MIT-ANP-TR-100 (2004)
