The Boiler provides the Steam ~ The Steam Engine provides the Power
There are many types of Steam Engines. The one I have chosen to use in my Steampunk themed fabrication area is a Compound Engine Unit. Specifically, I will be using a “Triple-Expansion Steam Engine” design similar to the engines used in Marine applications.
Prior to sinking in 1912, the RMS Titanic had two huge triple-expansion steam engines powering its two outer wing propellers. While my steam engine will be considerably smaller; the Titanic’s engines each weighed 1,000 tons, were 30 feet tall, and had an Operating Output of 16,000 h.p.
How a “Triple-Expansion” Steam Engine works…
Using the RMS Titanic as an example – Steam from the Titanic’s boilers, built up to 215 psi, entered the smaller High-Pressure (HP) Cylinder (Diameter 54″), moving the piston in the HP cylinder. The steam then exited the HP cylinder, and was piped to the next, slightly larger, intermediate pressure (IP) cylinder (Diameter 84″), moving the piston in the IP cylinder. The steam exited the IP cylinder, and was piped to the next, much larger, low pressure (LP) cylinder (Diameter 97″), moving the piston in the LP cylinder. (On Titanic, each engine actually had two LP cylinders to make the engines run smoother) The steam, now down to 9 psi (pounds per square inch), was then passed to a steam turbine that powered the center propeller. The steam was then passed to the condensers, where it was cooled, turning it back to water, ready to be passed to the boilers, where the whole process started all over again.
Below, I have created a “Moving” Mechanical Example to give a simple “visual representation” of the process :
“Cut-Away” View of a Triple-Expansion Steam Engine
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Specifications of My Steam Engine …
The reason Triple-Expansion steam engines were popular on ships is that the steam produced from “fresh water” could be re-condensed and used over-and-over within the system. Fresh water was a premium on the open (salt-water) ocean and was mechanically less corrosive to use in a steam powered ship.
I will also be using the leftover, reduced pressure, steam coming out of the LP Cylinder to power a “Double-Acting Stationary Steam Engine” that will in turn run several cooling fans, or heat-exchanger radiators, depending on the season. (The Double-Acting Stationary Steam Engine will be designed at a later date)
My Triple-Expansion Steam Engine will be approximately 9 feet long with a 12″ Dia HP cylinder, 18″ Dia IP cylinder, and a 26″ Dia LP cylinder.
Since it will take considerable time to complete the final designs of my version of a Triple-Expansion Steam Engine – Over the next few days, I will take a break from Steam Engine designs to create, and post, drawings of other “less complicated” metalworking tools.
More to come …
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