ASTM STP47751S PDF

In this report I shall attempt to give a short survey of the American power-generation industry together with estimates of our future demands on rotor forgings. Figure 1 gives an indication of the size of the equipment manufactured, and will also point out the number of heavy rotor forgings required for what is today only an average size machine. Figure 2 shows the rapid increase in installed generating capacity in this country. Currently, there are over 100,000,000 kw of installed capacity, of which 23 per cent is hydroelectric, 2 per cent is internal combustion, and the remaining 75 per cent is steam turbine. Consumption of electric power in the United States more than doubles every ten years, and there are many indications that this rate of increase will continue in the future. At the present time almost all steam turbines of over 100,000-kw capacity are of the reheat type in which the steam, after expanding through a relatively small number of stages, is returned to the boiler for reheating back to, or close to, the initial throttle temperature. Although the great majority of these units are of the single reheat type, a few very large units now in design or in construction are for double reheat in which the steam is returned twice to the boiler for reheating. Figure 3 shows the traditional rate at which throttle and reheat temperatures have increased through the years. This particular figure is not up to date at this writing (Nov. 1957) since it does not indicate a 1200 F (650 C) unit now in construction. The greatest percentage of our units are for 1050 F (565 C) or 1000 F (540 C) initial and reheat temperatures, although there are several outstanding machines either in operation or under construction which utilize higher throttle temperatures. For instance, there are several units in New Jersey which operate at 1100 F (595 C); the 125,-000-kw Philo unit of American Gas and Electric Co. is in operation with 1150 F (620 C) throttle temperature; while the Eddystone unit now under construction for the Philadelphia Electric Co. will have a 1200 F (650 C) throttle temperature.