How do steam boilers work? --- Dominic, Sacramento, Calif.
Marshall Brain Answers:
You find steam boilers in power plants, factories, steam locomotives, etc. The basic idea is simple - water is turned to steam with a source of heat.
Fire tube boilers are common. You have a big tank of water with tubes running through it. A burner creates heat (say with natural gas or oil as the fuel), and the hot gases flow through the tubes. The water in the tank boils and produces steam. The following video shows a cutaway drawing of a fire-tube boiler:
With a boiler like this, the tank is under pressure. That means that you need a water injection system to force water into the tank to refill it as the water boils away. It also means that a tank explosion is a big deal. In the early days of steam power, tank failures and explosions were fairly common.
In the following video you can see a very simple homemade steam boiler. Notice how concerned he is about the boiler blowing up and the precautions he has taken to prevent an explosion: