How Do Boilers Operate?

Boiller Basics

Boilers are devices to heat large quantities of water to steam. Boilers heat the water through heated fuel or an electric element much like someone boiling water for coffee might do. Unlike with making coffee, however, the goal of a boiler is not just to get hot water, but to capture the steam and keep it pressurized.

Fire Tube Boilers

A fire tube boiler contains a large, insulated tank of water with a little space at the top for steam. Inside the boiler is the fire tube. In modern boilers, a fire tube is a type of burner. Oxygen and natural gas are ignited inside the tube. The tube usually flows back and forth through the water and finally exits, venting the hot gases into the air. The heat from the gases seeps out through the tube into the water, heating it to the boiling point. The steam from the boiler then exits through a tube at the top.

Water Tube Boilers

Water tube boilers have basically the opposite configuration to fire tubes. In a water tube boiler, a single tube of water runs back and forth through a furnace, heating the water inside. Because only a small amount of water is being heated at once, water tube boilers can heat the water to extremely high temperatures. The downside is that they can't store as much hot water.

Boiler Uses

Water boilers are used for many different purposes. Originally, they were often used for steam engines and steam-powered machines. The pressure from the heated steam would push a piston, turning a wheel and providing power to the machine. Nowadays, steam power is still used in power plants. The heated steam runs through turbines, making them spin and turning electrical generators. Boilers are also used to heat many buildings. The heated steam is directed up through pipes into radiators, which conduct the heat out of the water and into the room. The cooled water then flows back down through other tubes to be heated by the boiler and turned into steam again.