should be reduced to ensure satisfactory combustion.
Velocities in Convection Sections of Boilers. To prevent undue erosion of
boiler convection tubes, the gas velocities through the convection section shall not
exceed velocities shown in Table 4 for the specific boiler, stoker, and fuel
Furnace Volume. For water-tube boilers, furnace volume is defined as the
cubical volume between the top grate surface (coal) or the floor (gas, oil) and the
first plane of entry into or between the tubes. If screen tubes are utilized, they
constitute the plane of entry.
Effective Radiant Heating Surface. Effective radiant heating surface is
defined as the heat-exchange surface within the furnace boundaries and, in solid-fuel
furnaces, above the grate surface that is directly exposed to radiant heat of the flame
on one side and to the medium being heated on the other. This surface consists of plain
or finned tubes and headers and plain surfaces, which may be bare, metal-covered, or
metallic-ore-covered. Refractory-covered surfaces should not be counted. The surface
shall be measured on the side receiving heat.
Computations of effective radiant heating surface for water tube boilers
shall be based on the following:
a) Bare, metal-covered, or metallic-ore-covered tubes and headers:
projected area (external diameter times length of tube) of the tubes or header.