PATRIOT MAX & STANDARD EVAPORATOR PAN SET 2019
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INTRODUCTION: THEORY OF OPERATION
A maple syrup evaporator works under the principal of a gradient. As the sap boils, it concentrates. As it concentrates,
the volume is reduced and the solids (sugar concentration) increase. As the volume is reduced the liquid works to
maintain the levels across the evaporator so less concentrated sap flows into areas where there is more concentrated
sap. During the evaporation process the percent of sugar will change from the incoming (approximately 2%) to the draw
off (approximately 66%).
FORMING THE GRADIENT
When the evaporator is first filled, the concentration of the sap is the same throughout. The gradient is formed as the
water is evaporated from the sap in the syrup pan and the flue pan, and as the new sap enters the flue pan.
As the sap boils it loses moisture and becomes denser / more concentrated. As it is becoming concentrated it loses
volume. As it loses volume additional sap will try to keep the levels constant and at the same concentration. This is
occurring in both the flue pan and the syrup pan.
In the flue pan less concentrated sap enters through the float box into the first flue pan compartment and begins to
concentrate. As it concentrates it moves toward the second compartment of the flue pan. Early in the boil the second
compartment will become denser as the “fresh” sap entering the first compartment from the float box keeps pushing
the denser sap around.
As the syrup pan boils, the sap continues to become denser. The flue pan sap is pushed into the syrup pan making sap in
the first syrup pan compartment less dense. The sap from the first syrup pan compartment is pushed to the next
compartment where the sap is denser and then to the densest compartment, the “syrup” compartment. The syrup is
drawn off the evaporator from this compartment and more sap flows across all the compartments of the evaporator to
replace the volume of syrup drawn off.
With a good gradient in place there will be a measureable difference in the liquid levels between one side of the syrup
pan and the other. You may note a difference of ½”.
PROPER OPERATIONS TO MAINTAIN GRADIENT:
Firing
Defoamer
Minimize Reversal Effects
During operations you will be working to maintain a consistent gradient. This is done through firing level, control of
foaming, and minimizing the effects of reversal.
Firing (if using a wood fired arch)
During firing you are seeking to maintain the same boil all the time. By doing so, the liquid “push” in the pans will
remain consistent. If the boil reduces, liquid depths in both pans will start to equalize, losing the gradient. In order to
maintain the boil the following should be of concern:
1.
Wood to use
a.
Mix of hardwood (longer lasting, more BTUs) and softwood (quicker, intense heat).
b.
Avoid slabs as they do not allow heat to evenly reach the pan
c.
Split wood to the diameter and sized in length to match the length of the grates in use
Width of Evaporator
Diameter to Split Wood
24”
2” to 3”
30” and 36”
2” to 4”
40” and 48”
2” to 5”
60” and 72”
3” to 6”
2.
Loading wood into the arch
