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How Steam Technology Works


The First Steam Engines

In the late 17th century, England faced a timber crisis as shipbuilding and firewood consumed forests. The ships were necessary for trade and defense, but coal was a suitable substitute for firewood. However, producing more coal meant digging deeper coal mines, which increases the likelihood of water seeping into the mines. There was suddenly an urgent need for new methods of pumping water out of mines.

In 1698, Thomas Savery, a military engineer, obtained a patent for a steam pump and began pitching his "Miner's Friend" to anyone who would listen. The device consisted of a boiling chamber that routed steam into a second container where a pipe with a non-return valve descended into the water that needed to be removed. Cold water was poured over the container of steam and as the water vapor inside cooled to a liquid state, the resulting vacuum drew up water from below. The sucked-up water was unable to flow back past the non-return valve and was then drained through another pipe.

Unfortunately for Savery, the steam pump didn't achieve the success in the mining industry he had hoped for. Most of his sales were made to private estates that wanted to drain excess water and repurpose it for home and garden needs. Because the steam chamber's heating and cooling had to be managed manually, the engine was somewhat impractical. The engine could also only draw up water from a limited depth -- a deep mine required a series of engines installed at various levels.

However, in 1712 the blacksmith Thomas Newcomen and assistant John Calley, a glassblower and plumber, created a more effective steam-powered pump system. The Newcomen Engine combined Savery's separation of the boiler and steam cylinder with Papin's steam-driven piston.

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While Savery sought to replace conventional horse-driven pumps with his engine, Newcomen sought to use a steam-driven pump to do the work of horses. Newcomen's engine was similar to Savery's. It included a steam-filled chamber that was cooled by a quick injection of cold water to create a vacuum-inducing change in atmospheric pressure. This time, however, the force of the vacuum pulled a piston down and pulled a chain that activated a pump on the other end of a suspended beam. When the water in the piston cylinder turned to steam again, it pushed the piston up and a weight on the other side of the beam reset the pump.

The Newcomen engine proved to be a major success and was used in hundreds of mines across Britain and abroad. While the engine operated at a slow pace, the cost of its operation was cheaper than maintaining a stable of horses. Engineers soon began to tinker with the Newcomen Engine -- improving the cylinders, valves and fuel efficiency of the steam pump. The creation of stronger iron made the engine more durable. Smelters soon found they no longer had to operate next to rivers, as the Newcomen Engine could be used instead of water wheels to power furnace bellows.

In the next section, we'll look at the advancements made by James Watt, whose discoveries are largely credited as bringing about the age of steam.