Water Wall For External Furnace

I want to convert an existing 5 Ton Oil Fired 150 PSI Fire Tube Boiler to Wood Fired by constructing External Furnace.

Since wood fired need more heating surface, I like to provide water wall (Radiative Heat Exchanger) in the duct that carries flue from Furnace to the Boiler.

Please give your valuable suggesions,
1. Is it possible to weld 2 stubs to boiler front end plate. To which we can connect Water Wall coil two ends.
2. Please suggest suitable material for water wall coil.
3. Will the Coil be over heated.
4. Since one end of coil is just tapped from boiler and again another end of coil is given to boiler shell, will the water in boiler remain stagnant.

Note:
Water wall is Helically coil wound as air tight and its inner surface is exposed to radiative heat.


with thanks,
Sachi.

 

[htb]

You can install a external furnace to your existing boiler, but the concept you seem to have, I am not sure about it.
What I would suggest is you install a water cooled ext. furnace complete with down comers riser etc.. to make the furnace air tight and reduce refractory the furnace can be of membrane contruction, since you want to fire wood you will have to provide suffceint grate area and furnace volume to unsure that full combustion takes place.

 

[srk]

Dear Mr.Sachi,

It is possible to implement down comer and riser,for that we have relocated the Shell to certain height for Natural flow circulation.In stead of fixing water wall,we can introduce the spirals in the existing tube by mean of which the overall heat transfer coefficient will be increased ....
Hope this is one of the economical option with low investment.....

 

[GenB]

You may need a form of A type water wall with 2 bottom headers spread apart and leave space for the refractored furnace floor. the top 2 headers to a t joint (together)
and flanged to one top outlet and connect ut to the top water side of boiler.
If in the US or Code/National Board controlled jurisdictions, you will need inspections/modification/alteration of the boiler by an authorized stamp holder S.
Elmer.