Boiler tube in air path

[coolniks37]

Hi

Due to an erection mistake, I have some tubes coming in boiler secondary air gas path.
What will be the effect, if I dont want to modify it?
Hardly 4 tubes of boiler wall,(approx 50mm length is exposed)
Air velocity is around 60m/s and at 250 deg c

Tube is cooled by water-steam mixture as well

Can I leave it as it is?
If I plan to shield it using 3mm SS sheet, what are the effects?

 

[dougarthur42]

I would worry more about other erection mistakes, if this one was made , what else. Boiler water wall tube coming in contact with incoming secondary air should be no problem functionally. But you stated air gas path which I assume is in the flue gas exit pass, which could cause a problem. If it is a solid fuel boiler such as coal the flue gas may contain solid fly ash which could cause erosion. Heat loss is probably minimal so don't worry about that. Shielding would be a good idea either with SS shield or refractory would be fine. Or just leave it.
Doug

 

[chicopee]

I would personally rectify the problem if I were the contractor in charge of the erection. As the owner of the boiler, I would not accept the mistake.