Optimisation potentials for the heat recovery in a semi-closed oxyfuel-combustion combined cycle with a reheat gas turbine

Publikationstyp
Journal Article
Date Issued
2014
Sprache
English
Author(s)
Mletzko, Jan  
Kather, Alfons  
Institut
Energietechnik M-5  
TORE-DOI
10.15480/882.2356
TORE-URI
http://hdl.handle.net/11420/3039
Journal
Energy procedia  
Volume
63
Start Page
453
End Page
462
Citation
Energy Procedia Volume 63, 2014, Pages 453-462
Publisher DOI
10.1016/j.egypro.2014.11.048
Scopus ID
2-s2.0-84922860798
Publisher
Elsevier
Semi-closed oxyfuel-combustion combined cycle plants are one possibility to realise CCS technologies with natural gas-fired power plants. Due to the recirculation of exhaust gas the working fluid in the gas turbine consists mainly of CO2. This leads to the necessity for an increased pressure ratio to achieve the efficiency and the exhaust gas temperatures of conventional gas turbines. In this work a conventional natural gas-fired combined cycle plant with a reheat gas turbine modified for oxyfuel operation will be presented. As it is assumed that the necessary pressure ratio is not realisable with axial compressors two different scenarios are considered. On the one hand the pressure ratio is the same as in the conventional process and on the other hand the pressure ratio is set to an assumed maximum of 60. The exhaust gas temperature lies significantly above the values of the conventional plant. Generally the higher pressure ratio results in a higher net efficiency of the plant. An unchanged heat recovery process results in a loss of efficiency of at least 9.3 to 10.8 %-pts. depending on the pressure ratio. Increasing the steam parameters can achieve a reduction of this loss ranging from 0.5 %-pts for the high pressure ratio to 1.0 %-pts for the low pressure ratio. An alternative approach for the heat recovery is the application of an internal recuperator in the gas turbine. When the achievable pressure ratio is far from the optimum value, as in the low pressure ratio case, this approach can lead to significantly lower losses of 9.1 %-pts. With a higher pressure ratio the effects of the optimisation options are similar.
Subjects
power plant
gas turbine
CO2-capture
oxyfuel
heat recovery
recuperator
DDC Class
620: Ingenieurwissenschaften
Lizenz
https://creativecommons.org/licenses/by-nc-nd/3.0/
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