THE REVOLUTIONARY POWER OF STEAM
And How It Changed The World
By Bill Dobbins
For most of history, humans have been limited in the ability to do “work.” Early on most work was done using human muscle power. Then people made use of the greater muscle power of animals – such as horses, oxen, elephants, camels and llamas. They also learned to make use of mechanical power. Windmills harassed the power of the wind and waterwheels that of flowing water.
But the major breakthrough in the availability of power, something so important that it made the industrial revolution possible, was the invention of the steam engine.
The fact that boiling water and capturing the resulting steam is a source of energy has been known since ancient times:
The first recorded rudimentary steam engine was the aeolipile described by Heron of Alexandria in 1st-century Roman Egypt. Several steam-powered devices were later experimented with or proposed, such as Taqi al-Din‘s steam jack, a steam turbine in 16th-century Ottoman Egypt, and Thomas Savery‘s steam pump in 17th-century England. In 1712, Thomas Newcomen‘s atmospheric engine became the first commercially successful engine using the principle of the piston and cylinder, which was the fundamental type steam engine used until the early 20th century. The steam engine was used to pump water out of coal mines. – Wikipedia
The earliest known rudimentary steam engine and reaction steam turbine, the aeolipile, is described by a mathematician and engineer named Heron of Alexandria (Heron) in 1st century Roman Egypt, as recorded in his manuscript Spiritalia seu Pneumatica. Steam ejected tangentially from nozzles caused a pivoted ball to rotate. Its thermal efficiency was low. This suggests that the conversion of steam pressure into mechanical movement was known in Roman Egypt in the 1st century. Heron also devised a machine that used air heated in an altar fire to displace a quantity of water from a closed vessel. The weight of the water was made to pull a hidden rope to operate temple doors. Some historians have conflated the two inventions to assert, incorrectly, that the aeolipile was capable of useful work
These early steam engines were relatively inefficient and could not generate enough energy to power machines that were able to do really significant amounts of useful work. It was Thomas Newcomen with his “atmospheric-engine” of 1712 who can be said to have brought together most of the essential elements in order to develop the first practical steam engine for which there could be a commercial demand. This took the shape of a reciprocating beam engine installed at surface level driving a succession of pumps at one end of the beam. The engine, attached by chains from other end of the beam, worked on the atmospheric, or vacuum principle. – Wikipedia
Steam engines were successfully used to power machines pumping water out of mines in 18th and 19th century England, as well as elsewhere. Even though these were relative inefficient that allowed for the continued operation of mines that would otherwise have not been able to supply enough of such things as the coal necessary to power the industrial revolution – and to pollute the air and cover industrial cities with blankets of soot and dirt.
But it was James Watt whose innovations to steam engine design that lead to really efficient and useful use of the energy of steam. Watt concluded that 80% of the steam used by the engine was wasted. Instead of providing motive force, it was instead being used to heat the cylinder. In the Newcomen design, every power stroke was started with a spray of cold water, which not only condensed the steam, but also cooled the walls of the cylinder. This heat had to be replaced before the cylinder would accept steam again. In the Newcomen engine the heat was supplied only by the steam, so when the steam valve was opened again the vast majority condensed on the cold walls as soon as it was admitted to the cylinder. It took a considerable amount of time and steam before the cylinder warmed back up and the steam started to fill it up.
Watt solved the problem of the water spray by removing the cold water to a different cylinder, placed beside the power cylinder. Once the induction stroke was complete a valve was opened between the two, and any steam that entered the cylinder would condense inside this cold cylinder. This would create a vacuum that would pull more of the steam into the cylinder, and so on until the steam was mostly condensed. The valve was then closed, and operation of the main cylinder continued as it would on a conventional Newcomen engine. As the power cylinder remained at operational temperature throughout, the system was ready for another stroke as soon as the piston was pulled back to the top. Maintaining the temperature was a jacket around the cylinder where steam was admitted. Watt produced a working model in 1765. – Wikipedia
Watt never ceased improving his designs. He further improved the operating cycle speed, introduced governors, automatic valves, double-acting pistons, a variety of rotary power takeoffs and many other improvements. Watt’s technology enabled the widespread commercial use of stationary steam engines.
With this new type of steam engine came the industrial revolution. Textile mills and other factories no longer had to be located next to a source of running water. Factories could be made much, much larger, including as many machines as wanted, simply by supply the necessary amount of steam energy. Steam engines also began to replace wind as the power source for boats and ships. Starting in the 1830s, we saw railroads using steam powered locomotives allowing for transport of people, goods and merchandize over vast distances at never before possible speeds.
Steam power continues to be used effectively today, although it is far less important in the age of the internal combustion engine and electric power – as well as modern and highly efficient wind farms and the use of solar power. But when you look around at the modern industrial and post-industrial age, remember it was steam power that got the whole thing moving in the first place.
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