Operating a balanced draft boiler on natural draft
Operating a balanced draft boiler on natural draft
(OP)
Does anyone have any experience of operating a water tube steam boiler which is normally balanced draft i.e. has FD and ID fan under natural draft only?
Both our fan turbines require major repairs and I've been asked what load could be achieved out of the boiler merely under natural draft.
I would be pleased to hear any tips/advice.
Both our fan turbines require major repairs and I've been asked what load could be achieved out of the boiler merely under natural draft.
I would be pleased to hear any tips/advice.





RE: Operating a balanced draft boiler on natural draft
RE: Operating a balanced draft boiler on natural draft
I have seen solid fuel boilers that had tall stacks operated at low, idling type loads (weekend operation for example) with all the fans off. But they wouldn't do much when a real load was applied.
rmw
RE: Operating a balanced draft boiler on natural draft
Bottom line: Try it but don't push it
RE: Operating a balanced draft boiler on natural draft
1)The combustion air flow& temperature are key factors in smooth and secure Burner Management systems& there bye for boiler operation.
2)The Efficient heat extraction from outgoing flue gases is ensured against incoming air through air pre-heaters etc. which form resistance to airflow only overcome through the FD fans.
3)The resultant extra work load on the ID fan (without FD Fan in use) can severely hamper overall capacity and safe combustion operation.
4)Thus slow but sure deposition of soot and other incomplete combustion products,consequential decrease in ID fan's speed due to heaviness and system clogging.
5)Not only consequent greatly reduced boiler capacity but Even the Boiler's operational Safety,Boiler Room's staff& Operating,nearby staff Life safety becomes in total jeopardy.You should appreciate.
Best Regards
Qalander(Chem)
RE: Operating a balanced draft boiler on natural draft
1. The natural draft might be possible to keep the fire going but the amount of heat generated can only keep the boiler itself warm but can produce barely any steam.
2. For combustion with insufficient air it is hard to maintain CO emission level within safe range.
RE: Operating a balanced draft boiler on natural draft
This seems like a very bad idea to me. For starters, I don't see how you can effectively accomplish a purge of the unit prior to light-off. I also would expect that you'd have to jumper across some of the limits in your burner management system to even light the pilot burners. And lastly, assuming you broke the rules and managed to light off the unit, I would expect that you cannot achieve much of a load at all.
I've seen the consequences first hand of a boiler that was lit off without its FD Fan running. Let's just say they had to replace the entire boiler (the steam drum landed several blocks away). Unfortunately, the operating personnel killed in the explosion were impossible to replace.
RE: Operating a balanced draft boiler on natural draft
case(1) Gas poses greater risk/danger of explosion(s).
case(2) Oil there is insufficient air flow& possibly temperature to have risks/dangers of inadequate stochiometeric ratio and non-sustainable combustion thus finally leading to possible explosion or flame extiguishment.
Best Regards
Qalander(Chem)
RE: Operating a balanced draft boiler on natural draft
you can not keep even the pilot on.
if the boilers were started normally with fans, fans down then the stack is hot and flowing you could get 10 - 20% output w/nat draft checking draft and combustion meassurements within acceptable limits.
but what good is it. quite dangerous.
RE: Operating a balanced draft boiler on natural draft
Best Regards
Qalander(Chem)