Steam Boilers are a form of large water content boilers used to provide customers with steam, as a heat transfer media. Typically, the quality of steam provided by these units is much higher than forced circulation steam generators. The higher quality of steam mitigates the use of steam separators or steam accumulators. When discussing steam boilers, there are two distinct types of large water content boilers, water tube and firetube.
Water tube boilers are designed with water inside the tubes of the boiler and hot gases surrounding the tubes. As the water temperature increases, steam begins to develop and travels to the upper portion of the boiler, typically called the steam drum. The cooler water travels through the down-comers to the mud drum where the water will be reheated.
Firetube boilers are designed with gases traveling through numerous tubes immersed in water. The hot gases heat up the tubes which heat up the water, in turn generating steam. Generally, firetube boilers do not produce steam at very high pressures due to the higher expense associated with fabrication.