1. Introduction - Firenze University Press

RH1
HP T IP T LP T LP T
DEA
RH2 RH3 RH5 RH6 RH7 RH8
5
New LSTG
HE4 (intercooler
of CO2 compressor)
30
HE2
HE1 ( Reboiler of
MEA Stripper)
Throttling one LP cylinder
4
COND
HE3 (CO2 cooler
of MEA Stripper)
3 2
Fig. 12. The structure of clutched LP turbine option
4.4. Results analysis
The performance analysis of three cases of this section is listed in Table 4, the three cases include:
Case 3: based on Case 2, Add a new letdown steam turbine generator (LSTG), as discussed in
Section 4.1;
Case 4: based on Case 3, adopting thermal energy integration, as discussed in Section 4.2;
Case 5: based on Case 4, Throttling one of LP cylinder, as discussed in Section 4.3;
Table 4. Performance analysis of Case 3-5
Base Case Case 3 Case 4 Case 5
Coal input rate (kg/s) 46.66 46.66 46.66 46.66
CO2 capture amount (kg/hr) - 447423 447423 447423
CO2 capture rate (%) - 90 90 90
Reboiler heat duty (MW) - 420.83 420.83 420.83
CO2 compression work (MW) - 39.91 39.91 39.91
Outlet pressure of LSTG (bar) - 3.0 3.0 3.0
Extracted steam flow (kg steam/kg CO2) - 1.553 1.553 1.553
Heat recovery from CO2 capture(MW) - 0 73.05 73.05
Power output of steam turbine (MW) 604 450.18 459.9 474.23
Power output of LSTG (MW) - 43.69 44.59 44.59
gross power output (MW) 493.87 504.49 518.82
Auxiliary work (MW) 30.22 85.51 85.51 85.51
Net power output 573.8 408.36 418.97 433.31
Net efficiency of plant (%) 40.28 28.67 29.41 30.42
Efficiency penalty (%-points) - 11.61 10.87 9.86
As is shown in Table 4, compared with Case 2, when a new letdown steam turbine generator was
added, the net efficiency of Case 3 can be increased by 2.27%-points, rising from 26.40% to