Saturday, 14 June 2014

Charles Parsons and Turbines


We all grew up with the story that James Watt watched a tea kettle boil and invented the steam engine. Rarely do we wonder why the Chinese tea makers never invented a steam engine. In school books, we also read Faraday discovered electricity or that Thomas Edison invented the light bulb. Even those of us who study physics or engineering later, rarely wonder why Faraday did not invent the light bulb. The nerdier, and more widely read people, know how vital Nikola Tesla’s experiments with Alternating Current were to the modern electrical world.

Of late, Tesla versus Edison has become a cult battle, with “kind, brilliant, public spirited” Tesla who wanted to make electricity free for the whole world winning hearts over cunning, capitalist, greedy, jealous, stubborn Edison, the latter approaching Voldemort in his villainy. Ungrateful world. Imbecile too, in its ignorance of basic economics. I would strongly recommend Vaclav Smil’s “Creating the Twentieth Century” to get a more realistic (and less cartoonish) perspective.

But today June 13, is Charles Algernon Parsons’ birthday, and since he is almost completely unknown to all but mechanical engineers, I’ll explain his vital role in making the modern world.
Edison invented the Electric Age (not just a working light bulb), the Spirit of Invention, the Corporate Research Lab, the Phonograph, ad infinitum. I rate Edison as the Man with the greatest impact and transformation of human history and civilization; not just the greatest inventor or engineer. The ones who surpassed him were the inventors of  Fire, Wheel, Agriculture, Cotton etc. whose names are lost in the mists of time. Energy and Transportation

Edison massively influenced Energy but not Transportation. James Watt’s steam engine influenced both, and there would be no Electric Age without steam engines – as coal fired power plants.

So did Parsons – his turbines are vital:
  1. For electric power – 75% of the world’s power is generated by steam turbines in coal and nuclear power plants.
  2. In jet aircraft engines.
  3. For powering the compressors used in the Haber-Bosch process, which helps feed the world.

Engines versus Turbines

Not being a mechanical engineer, and not having read much on engineering until recently, I didn't properly understand the difference between engines and turbines, and how much more efficient the latter are, until I read Vaclav Smil’s book Creating the Twentieth Century. And I did not realize how vital turbines are until I read his other book Prime Movers of Globalization – here is Bill Gates’ somewhat concise review.

James Watt did not invent the steam engine. Others like Savery and Newcomen made working steam engines before him. Watt’s great breakthrough was to devise anexternal condenser, which made the steam engine efficient and useful, and to invent several instruments which helped to incrementally improve the steam engine. Also Watt build stationary steam engines, which replace water mills as power sources in factories. He never built a steam locomotive, as in railways.

Richard Trevithick, George Stephenson and others increased it’s mass/power output ratio, leading to railways and cheap transportation as we know it. But these are reciprocating engines and still use steam power inefficiently. Water turbines existed in the 1830s, and in 1882 Gustaf Patrick de Laval made an impulse steam turbine. But Parsons, in 1885, made a small machine producing 7.5KW. When Edison dazzled the US with his Electric Lighting in 1879, he used a steam engine to generate power. As Smil rightly notes, it is the total design and planning of the electrical system needed to bring electric lighting, that was Edison’s giant transformation of the world. Edison’s use of DC, Tesla’s advocacy of AC, Westinghouse’s triumph are well known to those who know the history of electricity. But Parsons’ role, and the role of steam turbines is not properly understood or even unknown.

Alternating current is what enables cheap distribution of electricity. Without AC (or transformers), we would need power plants every few miles. Imagine the pollution, the logistics, the cost!

The Parsons Turbines

But AC only improves distribution, not the production of power. Here Tesla’s role ends. Early steam engines produced very little power for the amount of coal used. Steam turbines not only delivered more power, but massively improved the output per amount of coal used, as this table shows. Steam engines between 1890 and 1904 showed maximum thermal efficiency of 11-17%. It made no sense, economic or engineering, to install steam engines, rather than turbines, after 1902.

Year Turbine Power in KW Efficiency in %
1885 7 1.6
1888 75 5.0
1899 1000 25.0
1912 2500 75.0

This blog mainly outlines the impact of Parsons' improvements to turbine design and manufacture and their critical importance to the modern world. For more details on the engineering aspects of his work, and a brief biography, please read this.

I had earlier blogged in Tamil about Vaclav Smil on Edison.

2 comments:

  1. Good to read since I am basically a steam engineer specialised in Turbines and have worked on turbines developing i lakh HP. (I N S Mysore had four turbines driving four propellers at 1 lakh HP. I N S Vikrant had turbines developing 80000 Hp and my first ship I N S Rana had turbines (two) developing 40,000 Hp. In fact I was considered specialist in turbines!
    Later I sailed in motor vessels and obtained my diesel certificate as first class Motor engineer. Earlier I sailed in vessels of steam reciprocating engines which were low in HP but high in demanding maintenance. Parsons turbines fascinated me till I did my special training in Germany in water turbines and eventually Voith turbines which were unique. In fact I was the only Indian specialist in Voith tugs and used to take classes both in Calcutta and Madra for port engineers who use Voith tugs.
    As a steam engineer I was selected as the first flight deck chief of I N S Vikrant where the planes were catapulted into air at a speed of 100 mph. This system went out of use with the advent of SVTO planes. They use sloping deck to launch planes. Still I held the record of launching jet planes at 29 secs interval for very long time!
    It was with a heavy heart I left Vikrant. Anyway that is different story as I have had a colourful life professionally!
    Narasiah

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