New evaporator under way!

[tonka]

So I've started building my new evaporator. It is a 4'x17'. Instead of building the traditional drop/raised flue pan I wanted to do something different and more efficiant. The idea I got is taking the concept of a steam engine boiler and incorporating it into an evaporator (I see that I'm not the only one who has attempted this idea so I won't say it's 100% my idea). My tube pan will have 90 2" pipe 10' long which will calculate to about 450 sq ft of heated surface. I will be having aof and auf. When designing this rig I studied steam engine boilers/fireboxes and will be having a firebrick arch that will extend from the bottom of the tube pan 1/3 of the fire box horizontally towards the door that will act as a ramp for better combustion of the gasses.
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[wiam]

When I had this style pan it seamed to work best with about 1” gap under the bottom of the pan to the insulation. Mine was a Mason. Leader produced a few of these many years ago but they could not hold the solder joints between copper pipes and English tin pans. ( different expansions)

[tonka]

Not sure if I fallow you on having 1" gap between bottom of pan and insulation. I will be using stainless steel pipe for the tubes and they will be getting tig/mig welded into place.

[Mark]

Is it fire tube or is the sap in the tubes? What about cleaning under the tubes?

Here is an old Maple Digest that has a tube flue pan in it that you may find interesting.
http://www.maplesyrupdigest.org/?p=249

[tonka]

Fire in the tubes.

[tonka]

Thanks Mark for the link, interesting arrival. They made quite the design.

[whity]

Our Mason system is similar. We have a 2x8 with 16 2" tubes in the flue pan. about half inch apart. It boils over the extension we had built. As for 1" between the bottom of your drop tube pan and arch bottom is a good suggestion. We are running 1" as well.

[Woodsrover]

Cool idea!

[wiam]

Not sure if I fallow you on having 1" gap between bottom of pan and insulation. I will be using stainless steel pipe for the tubes and they will be getting tig/mig welded into place.

Fire went through tubes. Fire went under bottom of pan also. 1” gap under pan. I have seen no other pan boil as violently.

[Zucker Lager]

Most of the fire tube boilers I'm familiar with are fired through a large flue from front to back then they return that hot gas through smaller tubes to the front again where it vents to the chimney. I wonder if you could do that with your project and have the firebox flow go under the pan first then return to the front of the pan through the tubes? Drawback would be a chimney in the front of your arch. The total flow of hot gas would be longer maybe squeeze more BTU's out? just a thought Jay