The Stationary Steam Engine
The term stationary steam engine relates to any steam engine which was a fixed prime mover as part of an installation and covers a wide variety of purposes and types, some engines would be designed and built for a specific purpose or site, others would be 'off the shelf' as part of a manufacturers range.
The history of the steam engine is so large it would be impossible and impractical to attempt to cover it here with any hope of completeness - fortunately however, there is an excellent on line History of the growth of the steam engine Robert H Thurston. which, with numerous illustrations, should give all the background information anyone might require.
Before the advent of the internal combustion engine or electric motor, there was (other than animal wind or water power) only the steam engine to assist where power was needed.
The very earliest engines such as Thomas Savery's 'Miners Friend', Newcomens Atmospheric engines and the early James Watt engines used low pressure steam to displace air, once this had happened, the steam was condensed and collapsed back into a liquid, this left a partial vacuum and the pressure of the atmosphere (about 14 pounds per square inch of area in contact) was then used either to displace water or to move a piston, where the pressure of the steam was actually used it was low and not terribly effective. Most of these engines were used for pumping water either as some form of drainage or pumping water back up to operate a waterwheel.
Then came the 'high pressure' engines, pioneered by Engineers such as Richard Trevithick and Arthur Woolf, these used the pressure of steam to move a piston - often quite large - to provide mechanical energy again often for pumping but also for driving machinery and then road rail and marine engines.
Many different requirements led to an equally diverse range of engine designed and at the height of the steam age it was engaged in water and sewage pumping, drainage of both mine workings and agricultural land, winching and haulage, and driving a huge range of factory or other machinery.
A number of basic types evolved all of which had variants to suit particular jobs.
Horizontal or vertical cylinder(s) is the first distinction generally made, means of connecting the piston with its load comes next, beam engines had a large rocking beam for this purpose and either drove reciprocating pumps directly or rotated a flywheel to achieve rotary motion.
Where steam pressure was high enough, compounding was used, steam would first be used in a small diameter high pressure cylinder, after it had expanded and used up some of its energy it would be exhausted at lower pressure to a larger cylinder where it could do further work expanding and the pressure lowering further. Two cylinder versions are generally just called compounds, sometimes both pistons act on the same connecting rod and crank and would generally be called a tandem compound, sometimes each cylinder acts on a separate crank and would be called a cross compound, where the steam is expanded three or four times then the engine would be called a triple or quadruple expansion.
When the steam has no useful pressure left it would often be conducted to a condenser where in contact with a spray of water or cold surface it would turn back into water leaving a partial vacuum to 'suck' on the exhaust side of the biggest piston, at 14 psi vacuum on an engine with a 36" diameter low pressure piston this would add a force of 14,000lbs quite a significant figure.
Old enginemen tended to keep a very close eye on the barometer as the days atmospheric pressure affected how the boiler fire would draw and the absolute power delivered by an engine.
To Be Expanded