BOILERSDOE-HDBK-1018/2-93Miscellaneous Mechanical ComponentsFuelBoilerComponentsFigure 9 illustrates a typical fuel boiler. Some of the components are explained below.Steam drum -The steam drum separates the steam from the heated water. Thewater droplets fall to the bottom of the tank to be cycled again,and the steam leaves the drum and enters the steam system.Feedwater enters at the bottom of the drum to start the heatingcycle.Downcomers -Downcomers are the pipes in which the water from the steamdrum travels in order to reach the bottom of the boiler where thewater can enter the distribution headers.Distribution headers -The distribution headers are large pipe headers that carry thewater from the downcomers to the risers.Risers -The piping or tubes that form the combustion chamber enclosureare called risers. Water and steam run through these to beheated. The term risers refers to the fact that the water flowdirection is from the bottom to the top of the boiler. From therisers, the water and steam enter the steam drum and the cyclestarts again.Combustion chamber - Located at the bottom of a boiler, the combustion chamber iswhere the air and fuel mix and burn. It is lined with the risers.ME-05Rev. 0Page 16
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