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Posted by carl on May 21, 2002 at 06:41:33:
In Reply to: overheated boiler posted by Russ on May 16, 2002 at 20:14:34:
: We have a HRT externally fired low pressure hot water fire-tube boiler at our plant. It is fired by sawdust and is a three pass.
: Recently the front of the shell overheated. The front is where the hot gases make there last turn.
: The boiler had recently been re bricked and the arch to me looked like it had sagged. The contractors who did the work were back to look at it, and they diagnosed the overheating as air leaking in around the firetube cleaning access door.(this is where the signs of overheating are).
: They are saying that this air leakage mixed with the hot combustion gas has led to the overheating.
: My question is: If this air leakage has caused the gases to increase in temperature while making there passes.
: Is it safe enough to say that the firebox is not getting sufficient oxygen? And with that incomplete combustion comes with it more Carbon monoxide?
It is not an uncommon situation to have "post combustion" established in the later pass of a boiler. It sounds as if there is sufficient unburned fuel in the area of the cleanout doors. ID fan drawing additional oxygen into the area would then support reignition.