Sap Processing
Page 2

In a modern evaporator, the sap first flows into the "sap pan" (also known as the "flue pan"), where the sap is heated and evaporation is maximized.

In many sugarhouses the sap may have been preheated or partially evaporated before reaching the evaporator, through the use of techniques such as reverse osmosis, preheating, or vapor compression systems. You can read more about these systems by clicking here.

Because a tremendous amount of steam is created during syrup production, evaporators also include a hood or fan system that channels the steam outside. Many evaporators have a "piggy-back" system that improves efficiency by using the hot steam to preheat sap.

After leaving the sap pan, the concentrated sap flows into one or many finishing pans, where the final stage of the evaporation takes place. A finishing pan is typically a large, open pan heated from below.

In the the photo to the left, sap flows into the first finishing pan (there are three) towards the right of the photo.

As the sap evaporates and becomes denser, more incoming sap pushes it into the next finishing pan, and eventually into the third pan. By the time the sap reaches the end of the final finishing pan on the left, it has become syrup. An automatic drawoff valve releases syrup that will then travel through a filter and into a storage container.

Other producers use a single finishing pan on a separate burner, as shown in the photo below. Single finishing pans are used by producers who do not have an automatic drawoff system or do not have the time during sap evaporation to control final syrup density. Other producers use this type of finishing pan to reheat stored syrup when it is ready for canning.