1890

Steam Turbine

Sir Charles Parsons (1854–1931)

If you go to any large power plant today, one of the landmarks will be a huge steam turbine bigger than a bus. You find steam turbines on aircraft carriers and nuclear submarines, too. With the steam turbine, engineers were able to reconceptualize the extraction of power from steam and thus abandon pistons.

Let’s get in our time machine and go back to the engine room of the Titanic in 1912. Here they are using steam drawn from over one hundred massive coal-fired boilers and it is going into three steam engines driving three propellers. Two of these steam engines are gigantic piston machines that produce 30,000 hp (22 million watts) each, and the third is a steam turbine producing about half that. What we witness here is a period of transition. Steam turbines, first invented by Sir Charles Parsons in 1890, had not yet been perfected, but they would soon replace pistons to extract rotational energy from steam.

The basic idea behind a steam turbine is extremely simple. The expanding steam turns a series of vanes attached to a shaft. The vanes get progressively larger, so that the steam’s energy can be captured as it expands. Compare that process to the Titanic’s piston engines; the piston engines use three cylinders of increasing size. The steam first expands in the smallest cylinder. Then it flows to the next cylinder, somewhat larger in size to extract more power from the less dense exhaust of cylinder one. Then to the third even larger cylinder. This worked but made for a large and heavy piece of equipment. One steam piston engine on the Titanic weighed 1,000 tons.

A steam turbine does the same job, but is much smaller, lighter, and more efficient than an equivalent steam piston engine. Modern steam turbines appear in almost every major coal-fired and nuclear power plant today because of these advantages. Instead of just three expansion chambers, the steam turbine can have many stages of vanes of increasing size to extract as much power as possible. This shows how engineers switch to completely new concepts to get better results.

SEE ALSO High-Pressure Steam Engine (1800), Titanic (1912), CANDU Reactor (1971).

Contemporary turbines are so precisely made that they can only be constructed with computers.