Document M4Bv8N4oY2zdaRgvvn0XkRqbk

American Society of Heating and Ventilating ' Engineers Guide, 1932 Table 1. Approximate Full Load Efficiencies for Non-Gondensing Engine and Multi-Stage Impulse Turbo-Generators--Geared Type Rated Capacity at Full' Load Kw Mechanical Efficiencies or Engine . . Units Mechanical Eppiciencies or Turbine Units Brake Potential ErriciENcr Ratio or Turbines Factors fob Convert ing IDEAL WATER RATES TO ACTUAL WATER RATES (FOB TURBINES ONLT) Generator Efficiencies at Full Load " 100 200 300 400 500 600 750 1000 1250 1500 2000 0.900 0.905 0.910 0.915 0.920 0.925 0.930 0.935 0.940 0.945 0.950 0.930 0.935 0.940 0.942 0.945 0.947 0.950 0.952 0.955 6.957 . 0.960 0.45 0.50 0.54 0.58 0.61 0.64 0.65 0.67 0.67 0.67 0.68 2.22 1 ; 2.00 1.85 1.74 1.64 1.56 .1.54 1.49 f .49 1.49 1.45 0.932 0.934 0.936 . 0.938 0.940 0.942 0.944 0.945 0.947 0.950 0.954 500 600 750 1000 1250 1500 2000 Condensing Turbines 0.950 0.952 0.954 0.956 0.958 0.960 0.960 0.68 0.69 0.70 0.70 0;70 0.70 0.70 1.45 1.44 1.43 ' 1.43 1.43 1.43 1.43 0.940 0.942 0.944 0.945 0.947. 0.950 0.954 Single valve automatic engine units up to 400 kw._ Four valve automatic engine units up to 400 kw._ , Unaflow engine units up to 400 kw.____ (Fob Non-Condbmsiko Engines Only) 1.64 1.42 1.20 aThese factors are for indicated engine or brake turbine loads and do not take into account the mechanical efficiency of engine units or generator efficiencies for either engine or turbine units; but do include the mechanical efficiency of turbines. Table 2. Factors by Which to Multiply Actual Water Rates at Full Load to Obtain Estimated Water Rates at Fractional Loads on Non-Condensing Engine and Turbine-Driven Electric Generating Units15 Size and Kind of Unit . Load % H % Full Single valve engines up to 400 kw.... .................. four valve engines up to 400 kw. ...................... Unaflow engines, up to 400 kw_______ _________ Geared turbines up to 600. kw............................ Geared turbines 600 to 2000 kw.............. ............. 1.32 1.30 1.10 1.57 1.50 1.09 1.08 1.02 1.25 1.20 ] 1.03 1.03 0.980 1.05 . 1.04 1.00 1.00 1.00 1.00 1.00 bThese values are for indicated or'brake loads and do not take into account variations in generator efficiencies under various load conditions. Generator efficiencies vary from 85 per cent at one quarter load to 95 per cent at full load. 308 Chapter 21--Heating With Exhaust Steam ,; * Since 2546 Btu per hour = one horsepower7hour and 3415 Btu per hour one kilowatt-hour the heat extracted in performing work per pound of steam used may be obtained by dividing these figures by the water rates of the units per indicated horsepower hour or per kilowatt hour, respec- Fig. 4. Ideal Water Rate per Kilowatt Hour with Dry Saturated Steam for Various Initial Pressures and Back Pressures*15 aFor ideal water rate per indicated horsepower hour, divide these values by 1.34. bFrom Power from Process and Space Heating Steam, by L. A. Harding (A.S.H.V.E. "Transactions, Vol. 36.1930). tively, of work done by the steam. From 1 per cent to 2 per cent may be deducted for radiation and other heat losses, depending upon the size of unit. Example 1. A 200-kw turbine is operating on saturated steam at 150 lb gage pressure and consuming 40 lb of steam per kilowatt hour delivered, at full load. Determine the heat available in the exhaust for. heating. 309