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1. High pressure Boiler feed pumps are used to supply fresh water to a boiler. Condensation that forms in the boiler systems is typically recycled and fed back into the boiler with condensate return pumps.
2. There are three components typically selected together: the boiler, the feed water pumps, and the deaerator. The deaerator takes oxygenand carbon dioxide out of the feed water so pure water enters the boiler. It is essential to use a deaerator to remove impurities from the feed water, as these elements can shorten the life of the boiler.
3. There are two different types of boilers: fire tube and water tube. A fire-tube boiler works when hot gas passes from a fire through tubes running through a sealed container of water. The heat of the gas is transferred through the walls of the tubes by thermal conduction, heating the water to create steam2. A water tube boiler circulates water in tubes heated externally by the fire. Fuel is burned inside the furnace, creating hot gas which heats water in the steam-generating tubes3. Water tube boilers typically require higher pressures, and more flow from the boiler feed water pumps than fire tube boilers.
4. Boiler feed water pumping applications typically require high pressures due to the high temperatures of the feed water. Water changes to a gas state at 212-degrees F in atmospheric pressure. However, boiler feed water ranges are from 225- to 250-degrees F, and some can even reach temperatures as high as 350-degrees F. Therefore, to maintain the feed water in a liquid state, the deaerator tank and pump inlet piping often maintain pressures higher than the water vapor pressure.
5. There are two types of pumps that are most often used for boiler feed water applications: stamped stainless steel vertical multistage inline pumps and multistage horizontal ring section pumps. Vertical inline pumps can be used if pressure requirements are under 1,000 feet of head, but pressure requirements over 1,000 ft. typically require a heavy duty ring section pump – it all truly depends on the pounds per hour pressure capacity required and other demands of the boiler selected.
6. Understanding water quality is also critical for selecting the right materials of construction in your boiler feed water pump. Most specifying engineers should ask about additives; knowing what type of additive will be inserted into the water is necessary for choosing stainless steels or ductile irons to avoid corrosion, wear, etc. It’s important to have a conversation about the composition of the boiler feed water when selecting a feed water pump.
