Managing Concentrate In Head Tank.

[MT Pockets Producer]

I'm looking to see how others manage concentrate in their head tanks at the end of a boil? With our current wood fired set up we normally fill our head tank (30 gal) with raw sap as our rig is cooling down and it cooks off about half of that during the cool down period. With an RO planned for next year I am concerned about leaving 15- 20 gallons of concentrate in the tank between boils. What do others do? Keep raw sap on hand for final fill? We could run it down close to empty but have always been paranoid about damaging the pan if we did not calculate correctly. We run about 2 inches over the raised flues. Should this even be a concern? Thanks in advance.

Joe

[wiam]

I boiled for several years on a 2x6. Drop flue. I burned mostly hardwood. When I got to 7" in my feed tank I switched to pine. This would leave fewer coals. My last fire would be at 4". (Could vary slightly based on how much I was drawing. I learned this through experimenting. This would get me through cool down and not go much below the top of the flues. I don't think it hurts to get that low as the rig cools down. With my new oil rig I have discovered I can run the burner for about 5 minutes after sap stops coming in. This will leave the sap level right at the top of the flues. Just have to find the sweet spot for your rig. My feed tank is empty at the end of all boils. All tanks at the sugarhouse get pressure washed before bed.

[mellondome]

Why do you keep raw sap? You might as well run it all as concentrate and when the tank runs out fill it with permeate...

When I used to burn wood in my 2x6, I would stop adding wood with 20 gal left in head tank. When the fire was down to just coals, I would flood the flue pan with what was left. ( usually about 10 gal. ) after cleanup in would shut the arch blowers off and turn out the lights. This was with 12% concentrate. Never added raw sap to anything other than the ro.

[MISugarDaddy]

You really don't want to leave any concentrated sap in your head tank at the end of the day because the bacteria in the sap will go to work on the concentrated sugar level. As William said, you will need to experiment and find your setups sweetspot and stop firing at that point. With our setup, there is always about 10 gallons of raw sap left in the tanks when they get too low for the RO to have enough for it to run. When our feed tank gets down to 25 gallons we stop firing our unit, but sometimes, because of drawing off syrup at the end, we may run low, so at that time we put the raw sap in the feed tank to avoid running the pans too low. We empty all our tanks at the end of the day and give them a good cleaning too.
Gary

[maple flats]

I always finish off what is in my head tank. I put a T in the feed line from my head tank and attached a clear tube that goes up high and then dumps back into the head tank. Rarely do I get any going back, but it does happen at times. Then it only takes a boil or 2 to figure where to put a "final fueling" mark on the tube. I boil along normally but I watch the level as it nears the mark. At that point I stop adding wood and just a few minutes later I remove the cold sap float so the flue pan gets everything that is in the head tank. That usually brings the flue pan up 1.5-2" above normal, but since the fire is still going hard, it is only 3-5 minutes and the flue pans is in full boil. By the time I finish raking the coals level and get them down to a safe amount the flue pan is then usually at about 1" high. I then shut off the HP air (AOF/AUF), cover the syrup pan, close the cupola clean up and shut off the lights. When I return the next day, the flue pan is either at my normal operating depth (1/2" over the flues to maybe 3/4" over). I wash the head tank with permeate and then I then run the RO long enough to get up to my "last fueling" mark and at which time I light the fire. Since I light it with a 500,000 BTU propane weed burner torch, it is in full boil in about 15-20 minutes and in that time my head tank is up about 6-8" above the line. I concentrate slightly faster than my boil plus syrup draw rate, but when my head tank gets near 3/4 full (I only use a 150 gal head tank), I switch 2 valves and I'm then re-concentrating what is in the head tank, As it nears the line, I switch to ROing from raw sap again. I do this back and forth the entire boil (maybe switching every 45 minutes to 1.5 hrs.). It works good for me.

[Russell Lampron]

Raw Sap!!! Who wants to boil that stuff? I have a stop firing line marked on my sight tube so that I know when the head tank is almost empty. That mark leaves just enough concentrate in the tank to shut down. When I stop firing I pull the float on the flue pan and open the preheater drain valve. I then unplug the blower, turn off the bubbler and fill the front pan 2" deep. While the evaporator is cooling down I close the cupola and run my syrup through the filter press. I then do a final check on the evaporator and flood the front pan more if needed.

I have a separate cage tank that I use as a concentrate tank and recirculate into that until it is sweet enough to sent to the head tank. I normally concentrate to 14% and continue recirculating as I am boiling. I switch the tanks back and forth while I'm boiling until the level in the sweet tank is low enough to send it all to the head tank.

[PerryFamily]

I have a shut down line on my sight tube.
I have a water line plumbed in pex up to the feed tank
Depending on how close I am to syrup I may push one more draw with water until I quit firing
I'm not worried about diluting the back pan as I put the sweet from my filter press in it at the end of the night
Tank and feed line is always drained after every boil

[GeneralStark]

As others have said you just have to figure out timing. If your rig has a blower you can use it to "blow out the fire" so to speak. Definitely don't keep any concentrate in the head tank between boils.

[MT Pockets Producer]

Thanks for all the replies and input. Looking forward to working this out next season.

Joe

[ennismaple]

As others have said you just have to figure out timing. If your rig has a blower you can use it to "blow out the fire" so to speak. Definitely don't keep any concentrate in the head tank between boils.

Agreed. As the concentrate tank empties we'll pump 50-100 gallons (depending on how much fire we have left) of permeate up to the feed tank to push water through the pre-heater and ensure we have enough for cool down. I want the flue pan at 1/2" above boiling level when I walk out of the camp because I know it will be about perfect the next morning. Concentrate will go bad on you very quickly so get it all through when you can.