Steam engines originally developed at engines to either remove water from underground mines or to provide water to factories that were built away from rivers that could driver water wheels. They eventually became efficient and portable enough to provide motive power to tractors and train engines. The steam engine evolved to be even more efficient and powerful and now modern steam turbines provide almost all of the world’s electric power generation.
The First Steam Engines
The very first steam engines in practical use were designed to pump water out of coal mine shafts. The first three designs were invented, patented and produced by Thomas Savery (1698), Thomas Newcomen (1712) and James Watt (1765). Each inventor perfected the concepts and designs on the one who came before.
The first Newcomen engines were huge brutes — two stories high. They delivered around ten horsepower. Their first use was keeping water out of British coal and metal mines. [University of Houston]
These steam engines were simple and inefficient compared to what came next. Here are images of the first three simple steam engine designs.
The First Steam Locomotive
The first actual steam locomotive used to do something productive was made Richard Trevithick in the United Kingdom.
The first full-scale working railway steam locomotive was built by Richard Trevithick in the United Kingdom and, on 21 February 1804, the world’s first railway journey took place as Trevithick’s unnamed steam locomotive hauled a train along the tramway from the Pen-y-darrenironworks, near Merthyr Tydfil to Abercynon in south Wales.[5][6] Accompanied with Andrew Vivian, it ran with mixed success.[1] The design incorporated a number of important innovations that included using high-pressure steam which reduced the weight of the engine and increased its efficiency. [Wikipedia]
The first steam locomotive in the United States rolled down the B&O Railroad from Baltimore, Maryland in 1930. The B&O Railroad had existed before this however, powered by horses rather than locomotives. The engine was named Tom Thumb, referred to as “The Iron Horse” and was made by Peter Cooper of New York.
The big deal and debate at the time was whether or not steam locomotives could replace horses. But on August 28th of 1830, a race was conducted between Tom Thumb and a horse drawn rail car.
The race on August 28, 1830, between Peter Cooper’s diminutive Tom Thumb locomotive and the horse-drawn Baltimore and Ohio (B&O) Railroad car demonstrated the superiority of steam power. Though the gallant horse won eventually when mechanical failure stopped the locomotive, the Tom Thumb had led the race, rounding curves at 15 miles an hour. [Federal Highway Administration]
How A Steam Locomotive Works
A steam locomotive is what is called an external combustion engine. That means that the combustion that provides the power occurs outside the engine. Unlike the engine in a car or truck in which fuel and air mix and ignite inside the engine cylinder and drives the motion directly, steam engines have a large boiler that heats water to create steam. That steam is piped to a piston forcing it to move back and fourth. That oscillating, or back and fourth, motion is transferred to rolling, or rotational motion by rods connected to the wheels of the locomotive.
Here is a graphic from How Stuff Works that shows the major components of a steam piston engine. Click the image to go to the How Stuff Works article on Steam Locomotives to see an animation of the steam piston engine cycle.
Improvements to this design were created as well to gain efficiency.
Since steam engines draw power from expanding steam, a single piston only takes advantage of part of that expansion. So the steam exhausted from the first piston is still hot, so it still has power. Multiple expansion steam engine use steam exhausted from the first piston to drive subsequent pistons, which have to have a proportionally larger volume, to gain more power and efficiency.
Power Plants
While the coal fired steam engine has fallen out of industrial use, steam are still in common use to generate electricity from gas or nuclear power plants. As steam engine technology evolved they went from utilizing steam to drive oscillation (piston moving back and fourth) to driving rotation or a turbine. Like a wind mill, a steam turbine is powered by steam that is flowing due to pressure created in the boiler. This gains efficiency as the mechanical energy does not have to be converted from oscillating to rotating.
Turbines are only effective if they rotate at very high speed, therefore they are usually connected to reduction gearing to drive another mechanism, such as a ship’s propeller, at a lower speed. This gearbox can be mechanical but today it is more common to use an alternator/generator set to produce electricity that later is used to drive an electric motor.[Wikipedia]
While employed as direct drive on some ships and locomotives in the past, steam turbines now operate mostly power plants and some turbo-electric propulsion systems in ships. 90% of all the worlds electrical power is generated by a steam turbine.
Kind of interesting to think of steam power and technology that traces its evolution back hundreds of years as being so important to our modern society isn’t it…
-Mike
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