Given the high pressures and temperatures of steam engines, it's not surprising that explosive accidents have peppered the technology's development. For this reason, boilers -- ranging from simple pressure cookers to power plants -- are equipped with some manner of safety valve. When the pressure inside the boiler becomes too great, excess steam is released through the valve to prevent an explosion. These devises are typically weight or spring powered and require a set level of pressure to open the valve. However, accidents still occur. Explosions due to the intentional or accidental deactivation of safety valves were fairly common in the 19th century. The bad press from such incidents proved a hurdle to steam pioneers and inventors of the day. One of the more notable steam-related accidents of the 20th century occurred at the Three Mile Island Nuclear Generating Station. The accident began when pumps feeding cool water to the steam generators stopped running, resulting in increased steam pressure. This triggered the plant's release valve, but when the valve failed to close, the reactor core itself overheated.
The Steam Turbine
In the 1830s, British physicist Michael Faraday created an early electric generator called the dynamo. Other inventors soon set out to perfect a method by which a steam engine could create the rotary motion necessary to produce electricity. They soon discovered that there was a limit to the number of revolutions per minute a steam-driven piston could provide. But the solution to this problem was to be found, ironically enough, in the very technology Hero proposed in A.D. 75: the steam turbine.
Whereas Hero's steam turbine called for steam to be jetted from the perimeter of the object to be rotated, early 19th century engineers proposed directing steam straight onto blades attached to the perimeter of a wheel. However, steel was not yet strong enough to hold up to the stress of such rapid rotation. In 1884, British engineer Charles Algernon Parsons put new steel technology to use. He created a turbine capable of using compounded steam that turned a dynamo at 18,000 revolutions a minute. In 1890, his steam turbine and accompanying electric generator were installed in the Forth Banks power station. The technology soon spread through Europe.
Parsons also applied his steam turbine technology to naval purposes, introducing his vessel, Turbinia, at Queen Victoria's Diamond Jubilee in 1897. Parsons was subsequently commissioned to fit a Royal Navy destroyer with a turbine engine.
In the next section, we'll look at modern advancements in steam turbine technology.