Who is James Watt?
James Watt was a well known Scottish inventor, a mechanical engineer and a chemist who is well known for developing the Watt Steam Engine. Watt was born on the 19th January 1736 in Greenock, Scotland. He excelled from an early age during his education, showing a great passion for maths.
Following school, Watt helped out at his fathers business in a workshop, and during his time, he showed great skill in creating engineering models. After his fathers business failed, he moved to Glasgow to work as a mathematical instrument maker. The start of James Watt inventions.
James Watt Invention – The Watt Steam Engine
James Watt’s most well-known invention is the Watt Steam Engine which he commercialised with the help of Matthew Boulton. However, he did not invent the steam engine but drastically improved its efficiency by adding a separate condenser to the Newcomen steam engine, resulting in the Watt Steam Engine.
He also developed the concept of horsepower and the unit Watt, which is the SI unit of power.
The idea behind the Watt Steam Engine developed when he witnessed the steam from a kettle forcing the lid to rise. He took this further by undertaking experiments in labs investigating steam utilising a kettle as a boiler.
The central insight arrived for Watt in May 1765, and it was to condense the steam in a separate chamber from the piston and maintain the temperature of the cylinder by introducing a ‘steam jacket’.
Although having a working design, the capital was hard to come by, and following an original business partner going bankrupt, Watt met Matthew Boulton. Matthew Boulton provided Watt access to the best ironworkers in the world through his factory.
Watt and Mathew Boulton struck a brilliant business relationship, which later led to the founding of Watt & Boulton – a successful organisation.
What is a Watt Steam Engine
As discussed above, this is the most documented James Watt invention. A steam engine was original designed for water pumping out of mine shafts. Watt’s additional developments included a planetary gear set allowing the engine to have multiple uses, such as driving machinery.
The Watt Steam Engine works off the principle of creating a pressure difference created by a vacuum on one side of the piston, allowing it to push the steam piston down.
Unlike other steam engines, the Watt Steam Engine was hot at all times due to the addition of a separate condenser with the condensed product moved on with gases by an air pump.
The pressure difference created by the steam in the steam cylinder/piston results in piston movement, which is connected to a large wooden beam. The movement of the wooden beam acts as a lever and drives the water pump.
The system is designed such that the main pump side of the beam is heavier, allowing gravity to pull down that side of the beam. If it is necessary, weights are added to the beam on the main pump side.
Why Did James Watt Invent the Watt Steam Engine
Watt created the Watt steam engine because he found, through experience, that the current steam engine of his time, the Newcomen steam engine, was extremely inefficient.
He discovered this when he was given a Newcomen engine to repair. The design changes he implemented were patented in 1768.
Steam engine cycle
Imagine we start with the beam tilted to the left, as shown in the image. The cylinder below the steam piston is initially filled with atmospheric pressure steam, followed by a spray of water to condense the steam, creating a vacuum. The pressure difference between the atmosphere and the vacuum drives the piston down, pulling the main piston pump (not seen in the photo) upwards.
The upwards motion of the main pump piston elevated the water in the cylinder whilst also drawing in more water below the piston. At the bottom of the steam piston stroke, valves would operate to allow atmospheric pressure to take the place of the vacuum. The loss of the vacuum allows the heavier main water pump side of the beam to utilise gravity and pull it down, lifting the steam cylinder piston.
And then the process repeats.
Keeping the steam cylinder hot throughout the entire process is what made the Watt Steam Engine much more efficient than its counterparts.
Summary
Watt improved the Newcomen steam engine by adding a separate condenser and keeping the steam cylinder constantly hot. These additions drastically improved its efficiency.
The addition of a planetary geat set allowed the engine to drive machinery in addition to its original purpose, driving water pumps in mines.
Without Matthew Boulton, the great James Watt invention would have remained theory, and they went on to form a formidable partnership.