New to boiling on evaporator and having issue with front pan

[sshanny]

Folks,

We now have boiled 11 times on this new to us oil fired rig. 2x6 lightning with 201 Carlin gun. 60 degree 3 gal nozzle at 135psi. Have been working on chamber configuration to get even boil in front pan and decent boil in flue pan. The front pan is a 4 channel design. This last boil we started encountering the 3 channels closest to draw off boiling over into each other as we got near draw off temp. This of course causes mixing and batching which is not what we want. Prior boils have not had this happen. We would get good boil with bubbles getting to 3/4 of the channel height but never overflowing. Only way to prevent this so far is to defoam but that does not seem correct and only increases batching. Any idea what causes this and how we might correct the issue? We are running at 1.5 inches. Thanks.

[jmayerl]

There could be many causes to this most likely is inconsistent defoamer at sap entry. On our 2x7 we add 2 drops where the sap enters every 15 minutes is you think is needs it or not. Second most likely is niter build up,third most likely is higher bacteria levels in the sap.

[sshanny]

So are we supposed to defoam the front and well as back pans? I thought only the back? Niter is not an issue, just cleaned pans and when we shut down at end of boil they were still clean on the bottom, which was actually kind of surprising. We were boiling fresh sap gathered that day via the tubing system so I am unsure about the bacteria levels. Birx was at 2.6 on the raw sap. We don't have an RO. One thing that I just thought of is that flue pan has not been emptied this season, we just have been letting it freeze and we did not want to got through sweetening process again. Should we drain and clean the flue pan? We have only pushed 1500 - 2000 gallons of raw sap through the evaporator at this point. Thanks for all the suggestions.

[psparr]

Just need more defoamer in the flue pan.

[BAP]

Lower your pan depth some will also help.

[motowbrowne]

If your syrup pan is foaming over the dividers, yes, use defoamer there. Add it near where you're drawing off only. I know that it's best not to have to use it on the syrup pan at all, but there's no way that I'm gonna allow that much foam and risk scorching the pan. I learned from another producer to do what it takes to keep that foam down. Had some close calls before that. The others are right, though, in saying that if you are consistent enough and using the right amount of defoamer in the flue pan, you shouldn't need much in the syrup pan.

[Sugarmaker]

Yes defoamer as needed where needed. I had foam coming out of the top of the doors on my steam away this year! A couple drops of defomer and it was back in the pan.
I add a drop of defomer at the draw off each time I fire when I am close to syrup and a couple drops in the back pan too. Works for me.
Sounds like you are a expert on this rig now! The late season sap may boil up more too!

Regards,
Chris