The two most well known steam engines in the evolution of the steam engine were Newcomen’s and Watt’s engines. A lot has been written about them as the steam engine is credited for starting the Industrial revolution. What I am going to show in post is how both Newcomen and Watt applied exactly the same principle, the principle of separation, to significantly improve their steam engines over their predecessor’s.
The first known apparatus to create a vacuum by condensing steam was made by Denis Papin in the late 17th century. In 1675, Papin moved from France to London and started working under Boyle making various experiments with his air pump.
The way his contraption worked was as follows: about a third inch of water was poured into the cylinder and brought to boiling by fire under the cylinder. When the water was turned into steam it forced the piston up, which was latched at the top. When the cylinder cooled off the piston was unlatched and the pressure of the atmosphere forced it down. The thing to note is that the boiler that generated the steam was inside the cylinder.
Even though it was a great apparatus that had the key elements of the future steam engine (piston, cylinder and condensation), it needed further developments to work as a functioning, efficient engine.
Let’s skip forward to 1712 and look at the Newcomen’s engine.
Newcomen's atmospheric engine 1712
Newcomen’s engine consisted, among other things, of a cylinder, a beam, a piston, a separate boiler below the cylinder that provided steam and a valve to control access of cold water into the cylinder to condense steam. One end of the beam was connected to the piston and the other to a pump bucket.
When steam was condensed, the pressure of the atmosphere forced the piston down along with the end of the beam that was connected to the piston. The other end of the beam, which acted as a pump handle, was suspended and a pump bucket raised water.
There were several truly ingenious innovations in Newcomen’s design:
- The idea of condensing steam by spraying water inside the cylinder.
- The method of making the piston air and watertight inside the cylinder. At the time it was impossible to make the cylinder perfectly cylindrical, so the piston could not fit tightly inside the cylinder. Without an airtight fit, the vacuum could not be created in the cylinder. To solve this problem, Newcomen attached a leather flap around the edges of the cylinder and filled it up with water. The weight of the water would seal the leather. This was a clever solution!
- “Snifting valve” to drive any air that accumulated in the cylinder during condensation.
- Finally, Newcomen automated the openings and closings of the valve that controlled access of water into the cylinder for condensation. Take a look at “Plug frame’ in the image below. This long pole was attached to the beam and two tappets T1 and T2, which would close and open the valve W when the piston went down or up the cylinder. The method completely automated Newcomen’s engine; without this method, a person would have had to stand next to the engine opening and closing the valve during each cycle.
The Newcomen's Engine
The point that I would like to stress is that one of the fundamental differences between Newcomen’s engine and Papin’s apparatus was in the separation of the boiler. Papin’s contraption had the boiler inside the cylinder; Newcomen put the boiler to generate steam in a separate container.
Once again let’s skip a few years forward and look at Watt’s Engine.
In 1765, James Watt invented the most important innovation in the history of the steam engine. The Newcomen’s engine required heating up the cylinder to boiling temperature and then cooling it down to room temperature each stroke. This was inefficient and wasted a lot of steam. If Watt wanted to create a more efficient engine he had to solve the following contradiction:
The engine cylinder must be kept hot all the time in order to maximize efficiency and the cylinder must be cooled down once per cycle to maximize power.
Watt’s genius solution was in separating the condenser and the cylinder. This would allow the condensation of steam in a separate container while keeping the main cylinder hot. This innovation contributed a savings of almost 75% in fuel!
Watt's Engine - Separate Condenser
Just like Newcomen separated Papin’s unit that contained the boiler inside the cylinder into two independent parts, the boiler and the cylinder, Watt separated Newcomen’s unit that contained the condenser inside the cylinder into two independent parts, the cylinder and the condenser. It was exactly the same principle of separation!
The image below clearly shows this process.
The Principle of Separation & The Evolution of steam engine
This principle of separation is not unique to the steam engine industry only; it could be applied to solving different problems in different industries. Understanding it might help you solve your own problems. In one of my future posts I will write up a few examples of innovations from various domains that were invented by applying the principle of separation.
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References
Dickinson, Henry. A Short History of the Steam Engine. London: Cambridge University Press, 1939
Cardwell, D.S.L. From Watt to Clausius. Ithaca, NY.: Cornell University Press, 1971
Pacey, Arnold. The Amazing Ingenuity. Cambridge, MA.: MIT Press, 1992
