3 Comparison of various recovery steam cycle architectures

Page 1

Third project: comparison of various recovery 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 three dierent architectures of recov- ery steam cycle bottoming a gas turbine, characterized by growing complexity but also, as we will see, by growing performances. Before doing this though, we need to characterize our hot source, the gas turbine. We will use the same data of project 2 to nd its main parameters. This whole project was done using Turbogas , a software provided by Politecnico di Milano. 1 Gas turbine parameters The data we know from the previous project are the following: • electric power at the electric generator Pelnet,GT : 241.9 MW; • electric e ciency at the electric generator (based on LHV) ηel,GT : 38.0%; • exhaust gases mass ow rate ˙mexh: 659.8 kg/s; • exhaust gases temperature Tcc: 547.5°C; We now have to nd, knowing these data, the main parameters of our gas turbine: • mass ow rate of air at the inlet of the compressor ˙mair; • compression ratio βC; • total turbine inlet temperature TIT . 1.1 Parameters of the gas turbine To nd these parameters, we have to adopt an iterative approach. Like in any other iterative problem, starting from reasonable numbers will certainly help in converging quickly to the solution! So, where do we start from? The turbine we are examining is certainly a heavy-duty gas turbine, not an aeroderivative one: the output power is simply too big for any aeroderivative turbine (for reference, today's biggest aeroderivative turbine is GE's General Electric LM9000, capable of 63.75 MW, which derives from the GE-90, the biggest (thrust) turbofan ever produced, which ies the wide-body, twin-engined Boeing 777;…