preheater before piggy back pan ?

[bees1st]

Has anyboby out there tryed puttig a preheater before their steam-away or piggy back pan?

[TunbridgeDave]

Yes, my family invented the Piggyback pan back in the 80's. They took the preheater out of the hood that was on the rig and set it into a metal box on the floor and used that as the preheater. Works great! I think the hot water transfers more heat to the cold sap than the steam from the pig would since it's not as hot as a flue pan, but either way would work.

[bees1st]

Are you saying that they used the hot condensation water coming off the piggy back to pre heat the incoming sap? Why not ? It certainly produces a lot of hot water why not use it.

[Ausable]

When Boiler Condensate starts its path from the turbine condenser back to the Boiler it goes through many preheaters - several low pressure, high pressure heaters, economizer, lower water wall tubes etc before it is actually in the main part of the boiler - the idea is to be as efficient as possible - wasting as little heat as possible. It goes throught the lowest temperature preheaters first and works its way up........ So it makes sense to run cold sap through as many preheaters as possible so it is ready to boil when it hits the first sap pan.......and thanks for the preheating idea - I have never done this with sap and I don't know why ----Mike---

[TunbridgeDave]

Yes Bees1st, that's what I meant to say.

[bees1st]

I just had a quick thought on this ,the more you preheat the sap before it enters the piggy back, the less condensation you'll have from the underside of the piggy back pan, so it will reach a point of equilibrium .still better than cold sap going straight into the pan.