Modern Steam

Advanced steam technology (sometimes known as Modern Steam) reflects an approach to the technical development of the steam engine intended for a wider variety of applications than has recently been the case. Particular attention has been given to endemic problems that led to the demise of steam power in small- to medium-scale commercial applications: excessive pollution, maintenance costs, labour-intensive operation, low power/weight ratio, and low overall thermal efficiency; where steam power has generally now been superseded by the internal combustion engine or by electrical power drawn from an electrical grid. The only steam installations that are in widespread use are the highly efficient thermal power plants used for generating electricity on a large scale. In contrast, the proposed steam engines may be for stationary, road, rail or marine use.

Although most references to "Modern Steam" apply to developments since the 1970s, certain aspects of advanced steam technology can be discerned throughout the 20th century, notably automatic boiler control along with rapid startup.

In 1922 Abner Doble developed an electro-mechanical system that reacted simultaneously to steam temperature and pressure, starting and stopping the feed pumps whilst igniting and cutting out the burner according to boiler pressure. The contraflow monotube boiler had a working pressure of 750 psi (5.17 MPa) to 1,200 psi (8.27 MPa) but contained so little water in circulation as to present no risk of explosion. This type of boiler was continuously developed in the US, Britain and Germany throughout the 1930s and into the 1950s for use in cars, buses, trucks, railcars, shunting locomotives (US; switchers), a speedboat and in 1933, a converted Travel Air 2000 biplane.

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