Abstract
During 1920 the installation of three 30,000-kw. General Electric turbines was completed at the 59th Street power station of the Interborough Rapid Transit Company, New York City, complete tests upon one of which form the subject of the present paper.
These turbines are of the straight Curtiss impulse type, having 20 pressure stages, each pressure stage consisting of one velocity stage. The normal steam pressure at the throttle is 225 lb. per sq. in., abs. the steam being superheated 150 deg. fahr., and exhausted into a vacuum of 29 in. Hg. The speed is 1500 r.p.m. In addition to the primary steam inlet a secondary valve is provided which opens after the load reaches 24,000 kw. and which enables the turbine to carry a load of 35,000 kw.
The turbine tested was installed on a new reinforced concrete foundation. As no expansion joint was provided between the turbine and condenser, novel spring supports for the condenser were provided which are described in the paper.
The lowest water rate obtained during the tests while operating under normal conditions was 11.03 lb. per kw-hr., while the highest Rankine-cycle and thermal efficiencies obtained were 75.5 per cent and 25 per cent, respectively. Results of tests on the condensers and auxiliaries are also given in the form of tables.
The results obtained in these tests of a large power-station unit form a welcome addition to the data of tests of turbines of the same capacity installed in 1915 at the 74th Street power station of the company, reported in a paper presented before the Society in 1916, by H. G. Stott and W. S. Finlay, Jr.
