Reheating in Steam Turbines

This paper outlines the history of the reheat cycle, in which steam is resuperheated after expanding through the high-pressure section of the turbine, and shows the improvement in thermal efficiency to be derived from its use under various operating conditions. Such factors as regenerative feedwater heating, pressure drop through the reheater and its piping, and the temperature to which steam is reheated affect the gain in thermal efficiency obtainable with reheating. Reheating reduces throttle and exhaust-steam flows, exhaust moisture, and heat absorbed by the condenser. The effect of all of these factors is illustrated by the curves included in the paper.