Abstract
Experience has shown that as the ratio of the number of stages of a turbine operating in the superheated region to the number operating in the moisture region is increased, the actual thermal efficiency is improved at a rate far in excess of the theoretical value. The results of a large number of tests on turbines at different superheats have been analyzed to form a basis for calculating the gain in thermal efficiency due to resuperheating. In this paper, these results are given showing that the heat consumption of a turbine installation may be decreased from 6 to 7 per cent as a result of resuperheating the steam. There seems to be a rather broad pressure range at which the resuperheating may take place in order to show approximately the maximum saving. The probable gain due to more than one resuperheating has been obtained. These results indicate that, when taking into account the pressure drop in the resuperheaters, the gain possible by going to more than two stages of resuperheating would be very small. The effect of resuperheating upon the exhaust conditions and capacity of the turbine is discussed. Curves are presented to show that the gains due to the resuperheating and the regenerative cycles are very nearly independent of each other and that these features may be used in the same turbine, with the expectation that the savings due to both will be nearly additive.
