[Steam-engine] Firebox door (rookie question #999,999)

[Andre' Blanchard]

A clean efficient burn requires some percentage of secondary air (air 
coming in above the grates) if it is heated  so much the better.  The 
problem is getting it well mixed with the gases from the fire so that they 
can be burned, this is where poorly designed furnaces fail and send a 
significant volume of unburned gases (mostly carbon monoxide) up the 
stack.  A lot more thought goes into primary and secondary air control on 
stationary boilers then on traction engine boilers.  Traction engines seem 
to be designed more toward the max amount of power out of a minimum size 
boiler and efficiency is of a lesser concern, the fuel is cheap.  So 
cooling the door is probably one of the more important uses for the 
secondary air on a traction engine.
_________
Andre' B.  Clear Lake, Wi.

At 07:39 AM 4/27/2005, you wrote:
>Jeff and James, thanks for the input.  I kind of
>suspected that it had someting to do with cooling but
>wasn't sure.  I've see openings on other boilers and
>even coal/wood stoves and could never understand their
>function.  Even SIAM's little vertical boiler has a
>damper in the door.  Seems like it would be
>counterproductive to ever open it almost the same
>effect as opening the door all of the time..  Guess
>that I worry to much.