In this type of heater a steam used to heat the air flow. The heater consists of set of heating banks. Each bank contains has multiple of U-tubes with extended surface fins for passing a steam.

Related Terms


The maximum pressure for which the boiler was designed and constructed; the maximum gauge pressure on a complete boiler; and the basis for the setting on the pressure relieving devices protecting the boiler


A deep bulge in the bottom of the shell or furnace of a boiler.


The cylindrical portion of a firetube boiler shell that surrounds the tubes.


The term applied to that portion of a station or boiler load that is practically constant for long periods.


The number of pounds per square inch of pressure drop in a boiler from the point where the safety valve pops to the point where the safety valve reseats.


The drain connection including the pipe and the valve at the lowest practical part of a boiler, or at the normal water level in the case of a surface blowdown. The amount of water blown down.


A valve generally used to continuously regulate concentration of solids in the boiler, not the drain valve.


A closed vessel in which water is heated, steam is generated, steam is superheated, or any combination thereof, under pressure or vacuum by the application of heat from combustible fuels, electricity, or nuclear energy. The term dose not include such facilities of an integral part of a continuous processing unit but does include fired units of heating or vaporizing liquids other than water where these units are separate from processing systems and are complete within themselves.


A pressure part of the boiler consisting of a flat tube sheet into which the ends of the water tubes are rolled. In a parallel plane is a tube cap or handhole sheet. The two sheets are spaced about 4 to 8 in. or more apart. The top and bottom and both ends are flanged together and riveted or may be closed by a narrow flanged strip of plate riveted to each sheet. Circulating nipples connect the top of the header and drum, or the header may be flanged and riveted directly to the drum. Welding would be used today instead of rivets.


A valved opening in the top of the highest drum of a boiler or pressure vessel for venting air.

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