Thermal Cycle and Layout of a Pulverized-Coal—Fired Power Plant

The thermal cycle of a 750-MW size pulverized-coal—fired reference power plant is shown in the heat balance diagram of Figure 2-1. The pulverized-coal—fired steam generator provides main steam of 4133 psia/1112°F (285 bar/600°C) and reheat steam of 870 psia/1112°F (60 bar/600°C). The supercritical steam is generated in a once-through Benson-type boiler with a steam generator efficiency of 95%. The turbine is a single-reheat steam turbine with 2 double-flow LP turbine sections. The HP turbine is designed as a single-flow turbine with an extraction at a pressure of about 1360 psia (94 bar) to provide a final feedwater temperature of 581°F (305°C). The main steam expands in the HP turbine to cold reheat steam parameters of 935 psia (64.5 bar) and 684°F (362°C). Cold reheat steam is fed back to the reheater section of the boiler and after being reheated to 1112°F (600°C), enters the double-flow IP turbine, which features 2 extractions for feedwater heating and for steam supply to 2 boiler feedwater pump turbines. The IP turbine exhaust steam with a pressure of 67 psia (4.6 bar) enters the 2 double-flow LP turbines. The LP turbines are equipped with 3 extractions for the LP feedwater heaters. With the extraction steam supply from the HP and IP turbine exhausts, the thermal cycle features 8 extraction points for the 8 feedwater heaters.