WATERTUBE VS. FIRETUBE STEAM BOILERS
Watertube and firetube boilers are essentially the opposite in design. In a watertube boiler, water travels through tubes which are surrounded by the by-products of combustion, or flue gas. In a firetube boiler, the flue gas travels through the tubes, which are surrounded by hot water. Firetube boilers are typically designed with either three or four sets of tubes (three- or four-pass boilers). Every set of tubes that the flue gas travels through is considered a “pass”. Boilers designed for three-passes have the stack at the rear, and boilers designed for four-passes have the stack at the front. A boiler with more passes has a higher heat extraction rate and is more efficient then one with less passes.
From a maintenance standpoint, firetube boilers are typically have lower operating costs comparable to a similarly sized watertube boiler. Firetube boilers have easy access to the boiler’s firesides and tubes can easily be replaced without additional repair of the boiler. Although firetube boilers are smaller in design, they have a larger water volume than similar size watertube boilers, causing them to take longer to bring up to operating temperature from a cold start. Once a firetube boiler is started up and is operating at its desired pressure, a firetube boiler can handle a sudden upward load surge better than a watertube boiler because of the large steam disengaging area. The drawback to this feature is once the pressure of a firetube is dropped, it takes longer to catch back up. With less water volume, a watertube boiler has the ability to follow load swings more precisely and generally has better turndown than a firetube boiler.
View our current inventory list that includes a wide range of new and reconditioned firetube and watertube boilers.
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