Please help me understand pan sweetening

[SmellsLikeSyrupNH]

Hi everyone,
For the past few years I boiled on flat pans with no dividers, this year I got new pans with dividers. The pans are still flat and are 2x4 and 2x2 on the new 2x6 evaporator.

A few questions:

Im assuming the rig has to be as level as possible to get the gradient to set up, Is this really an important factor or will the gradient still set up if its not perfect?
I was reading that some people take 200 gallons before the pans are sweetened. I don't get that, do you draw off at all to get to this point? How does the final chamber not turn to syrup after boiling that long?
Also if im running my depth at 2-3" I would have to get syrup way before I go through 200 gallons of sap. Right?


Thanks in advance!
-Scott

[BAP]

Scott, you want your evaporator to be as perfectly level as you can so you don't end up with any low spots in the level of the sap causing a burnt spot in the pan. As far as establishing a gradient, it does take a lot of sap to get to the point of drawing off syrup. Also, you naturally get syrup at the draw off point because you are adding fresh sap at the other end of the evaporator and it keeps pushing the concentrated sap towards the other end. Also, the evaporator will boil faster if you don't get your pans too deep. 1" to 2" is sufficient as long as you pay attention. When you get really good at it, some people run 3/4"-1" deep allowing a faster boil which can help make lighter colored syrup. At those depths, you have to be on your toes to make sure you don't get too shallow and burn your pans. The difference between enough sap and too little is not much and can happen fast.

[SmellsLikeSyrupNH]

Thank you BAP, I will have a float box and will get the level adjusted and stabilized once I get used to the setup.

[Big_Eddy]

Read through this thread. It should answer a lot of your questions. http://mapletrader.com/community/showthread.php?23070-Sweetening-the-Pans-Continuous-Flow

Fire away (pun intended) once through the thread above

[BAP]

Your welcome. Good luck and feel free to ask more questions.

[Bricklayer]

Last year was my first year with a divided pan. I started at 2" depth. Then as I got a little gradient and more comfortable with the way it worked I slowly lowered the depth to about 1" then when I started getting good draws I went to 3/4". It's pretty hairy when it's that low. Just make sure you don't draw off more then your float box can allow into the pan. I almost had my pan down to 1/4" at one point on a good draw. That was with a 1/2" feeder line to the float box. So I changed it next day to a 1 1/4 line. If I get in trouble I just press the float down and it floods the pan very quickly. I also teed off an oh **** line to the back of the syrup pan with a valve. I am either loading wood, on the float box side checking to make sure the sap is coming in,or. On the draw off side staring at the temp and watching the bubbles. So I wanted to have access to a quick flood if possible. Haven't had to use it yet but it's there if I need it. I have a flat pan too and I get a ton of nitre build up on my draw off ball valve. What I do is every now and then when I'm ready to draw off is crack the valve wide open for 1 second or two. Clears the nitre out of the valve.

[BAP]

I run 3/4"-1" deep in my pans. But I keep a 5gal bucket of sap or water next to the evaporator for the oh s*** times when something happens and can't get sap in fast enough threw the float valve. Dumping a bunch of sap or water in and screwing up the gradient is much better than burning the pan.

[SmellsLikeSyrupNH]

Big Eddy,
I found your thread after I posted this, thank you for sharing that knowledge.....Im still confused as to why it would take all that sap to sweeten but I guess I'll get to see it in action in about 118 days or so :-)

[Big_Eddy]

Big Eddy,
I found your thread after I posted this, thank you for sharing that knowledge.....I'm still confused as to why it would take all that sap to sweeten but I guess I'll get to see it in action in about 118 days or so :-)

Click on the bottom link in my signature, and there is some discussion on the amount of sap needed.
Essentially, when the gradient is established, if you were to line up every "unit" of sap/syrup in your evaporator, the first "unit" would be 100% sap and the last "unit" would be 100% syrup. If we call the first unit a "sap", and assume a 40:1 ratio, that last "unit" (syrup) is the equivalent of 40 "saps".
Every "unit" between the first and the last can be converted to an equivalent number of "saps". ie. first unit = 1 sap. Last unit = 40 saps, midpoint = 20 saps. Etc.

Add them all up and the AVERAGE concentration in your evaporator is "20 saps" per unit. Stated another way - 20x as much sap went into the evaporator than the volume it is holding at any given time.

This is a somewhat simplistic view and does not take into account the number of sections, mixing, differences in evaporation rates between sections etc. It does give you an idea though, of the amount of sap that will be needed. Typically I find that flue evaporators running shallow take less sap than calculated above, while flat pans and running deep takes more.

[ennismaple]

Getting the pans sweetened to the point where you are running off syrup doesn't take any extra effort other than firing like crazy with nothing to show for it! As long as you are constantly adding fresh sap to the back of the pans through the float box the front channel will become syrup first as long as its boiling at the same rate as the rest of the pan. The raw sap will push the sweetened sap towards the front. The sap in the front channel will continue to get thicker and thicker until it is syrup.

For us, I can start with an empty evaporator and be drawing off syrup 90 minutes after my first big fire - but that's because we're running 2 RO membranes. My cousins have the same evaporator and need to boil for 4 hours before they get any syrup to run off.