5 Comparison of advanced steam cycle architectures

Page 1

Fifth project: comparison of advanced steam cycle architectures Simone Fedeli 892133 Luca Grippo 829683 Filippo Mecarelli 892120 Francesco Persico 893256 November 2017 1 The purpose of this analysis is to compare the performance of six dierent con gurations of a USC steam plant. We consider the rst con guration as the reference one, while in the others we have some key changes, as follows: Con guration A • superheater outlet mass ow rate: 1850000 kg/h; • superheater outlet steam pressure: 270 bar; • number of reheats: 1; • number of preheaters (deaerator included): 8, of which 4 for LP and 4 for HP; • number of mid-pressure two- ow rotors: 1; • number of low-pressure two- ow rotors: 2; • last stage blading: 33.5 inches - mean diameter 99.5 inches; • steam temperatures: 580 ‰ /580 ‰ ; • condensing pressure: 0.05 bar; • fuel: coal; • exhaust gases stack temperature: 150 ‰ ; • O2 concentration in exhaust gases at the stack: 5%; • economizer water inlet temperature: 315 ‰ . Con guration B • fuel: natural gas; • exhaust gases stack temperature: 120 ‰ ; • stack O2 concentration in exhausts: 2.5%. Con guration C • condensing pressure: 0.1 bar. Con guration D • steam temperatures: 640 ‰ /640 ‰ . Con guration E • number of preheaters: 4, of which 2 for LP (including deaerator) and 2 for HP; • economizer water inlet temperature: 280 ‰ . Con guration F • number of reheats: 2; • steam temperatures: 580 ‰ /580 ‰ /580 ‰ . 2 1 Second-law analysis of all con gurations First of all we analyze all con gurations with a second-law perspective in order to better understand the liabilities of each con guration. Using the software CicVap we have come to the following plot: As we can see, all con gurations have roughly the same second-law e ciency which stands between 40.5 and 43.4%. Being…