The Return of the Steam Engine

This paper discusses current applications of steam engines in industrial systems and new technologies which are improving their performance. The primary advantages of steam engine use come from applications where current technologies are either not appropriate or cannot be scaled down in size. Examples are given showing cases where it is more cost effective (and efficient) to use steam engines including dispatched power, use of a lower grade gas turbine with a steam engine bottoming cycle especially in CHP applications with a large heat to power ratio, and in secondary heat recovery systems. For small systems, the steam turbine is not appropriate because of its small turndown ratio, sensitivity to steam quality, and high operating speeds. This results in available steam power being wasted. Steam engines scale down in size beautifully, work better with wet steam, and operate with very modest operating speeds.