Economic analysis and research on feed water pumps coaxially driven by turbine for 1000Â MW direct air-cooling units

In the air-cooling units, the routine configuration modes of feed water pumps, electric-driven mode and/or steam-driven mode, have many disadvantages during the operation process. Aiming at another driving mode, namely feed water pumps coaxially driven by turbine, the concrete system configurations are put forward and analyzed detailedly in this study. For the electric-driven, steam-driven and coaxial-driven configurations, a mathematical model based on the equivalent heat drop method is developed to perform the economic analysis of 1000 MW direct air-cooling unit under four operating conditions. The results demonstrate that the station service power consumption rate of the coaxial-driven configuration is around equal to that of the steam-driven configuration, but approximately 3% lower than that of the electric-driven configuration. Additionally, compared with the electric-driven and steam-driven configurations, the net coal consumption of power supply for the coaxial-driven configuration decreases by about 0.7 g/kW h and 1 g/kW h, respectively. Certainly, coaxial-driven configuration has the maximum annual earnings and the increased initial investment can be recouped in 5.6 years for the Turbine Heat Acceptance (THA) condition. Apparently, feed water pumps coaxially driven by turbine is the optimal scheme and thus should be applied widely in future for the 1000 MW direct air-cooling units.