Watertube Boilers in Houston, Austin and San Antonio

What is a WATERTUBE BOILER?  A water tube boiler is a type of boiler in which water circulates in tubes heated externally by the fire. Water tube boilers are used for high-pressure boilers. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes. In smaller boilers, additional generating tubes are separate in the furnace, while larger utility boilers rely on the water-filled tubes that make up the walls of the furnace to generate steam.  The heated water then rises into the steam drum. Here, saturated steam is drawn off the top of the drum. In some services, the steam will reenter the furnace through a superheater to become superheated. Superheated steam is used to drive turbines. Since water droplets can severely damage turbine blades, steam is superheated to 730 °F (388 °C) or higher to ensure that there is no water entrained in the steam.  Cool water at the bottom of the steam drum returns to the feedwater drum via large-bore ‘downcomer tubes’, where it pre-heats the feedwater supply. (In ‘large utility boilers’, the feedwater is supplied to the steam drum and the downcomers supply water to the bottom of the waterwalls). To increase economy of the boiler, exhaust gases are also used to pre-heat the air blown into the furnace and warm the feedwater supply. Such water tube boilers in thermal power station are also called steam generating units.

How have WATERTUBE BOILERS advanced over the years?  The older fire-tube boiler design – in which the water surrounds the heat source and the gases from combustion pass through tubes through the water space – is a much weaker structure and is rarely used for pressures above 350 psi (2.4 MPa). A significant advantage of the water tube boiler is that there is less chance of a catastrophic failure: there is not a large volume of water in the boiler nor are there large mechanical elements subject to failure.

WATERTUBE BOILERS versus FIRETUBE BOILERS in Industrial Applications