PSM V57 D424 Details of the serpollet carriage

A flash boiler is a type of

water-tube boiler A high pressure watertube boiler (also spelled water-tube and water tube) is a type of boiler in which water circulates in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which boils water in the steam-gene ...

. The tubes are close together and water is pumped through them. A flash boiler differs from the type of monotube steam generator in which the tube is permanently filled with water. In a flash boiler, the tube is kept so hot that the water feed is quickly flashed into

steam Steam is a substance containing water in the gas phase, and sometimes also an aerosol of liquid water droplets, or air. This may occur due to evaporation or due to boiling, where heat is applied until water reaches the enthalpy of vaporizat ...

and superheated. Flash boilers had some use in

automobile A car or automobile is a motor vehicle with wheels. Most definitions of ''cars'' say that they run primarily on roads, seat one to eight people, have four wheels, and mainly transport people instead of goods. The year 1886 is regarded ...

s in the 19th century and this use continued into the early 20th century.

History

There is disagreement about the exact definition of a flash boiler. Some writers use the term interchangeably with

monotube boiler A monotube steam generator is a type of steam generator consisting of a single tube, usually in a multi-layer spiral, that forms a once-through steam generator (OTSG). The first of these was the Herreshoff steam generator of 1873. Principles F ...

and there is even use of the term ''semi-flash boiler''. However, the flash boiler is generally attributed to

Léon Serpollet Léon Serpollet (4 October 1858 – 1 February 1907) was a French engineer and developer of flash steam boilers and steam automobiles. Léon Serpollet was born in Culoz, in the Ain department of France in 1859, son of the carpenter August ...

who used a flash boiler in the Gardner-Serpollet steam-powered car from 1896. Serpollet's boiler was a low-water-content type with thick-walled tubes to provide a store of heat. Serpollet patented a steam generator in 1888, US Patent 379,421, but this is an early version which differs from the one illustrated above.

Characteristics

Flash boilers are lighter and less bulky than other types, and take less time to raise steam from a cold start. On the other hand they are more prone to overheat, because there is no large reservoir to cool the tubes if the water flow is interrupted or inadequate.

Fuel

Flash boilers are normally fired by liquid or gaseous fuel because this allows a quick response to changes in the demand for steam. However, experiments with solid fuel firing have been made.

Uses

Historically, flash boilers were used in some

steam car A steam car is a car (automobile) propelled by a steam engine. A steam engine is an external combustion engine (ECE) in which the fuel is combusted outside of the engine, unlike an internal combustion engine (ICE) in which fuel is combusted in ...

s, where rapid steam-raising was an advantage. During the Second World War they were used in Royal Navy Steam Gun Boats (SBGs). Modern use is largely confined to model steam boats.

References

Bibliography