Maple syrup producers use shell and tube heat exchangers and membranes to improve production
Leave a CommentMaple syrup is a beloved topping many people reach for when diving into a plate of pancakes or waffles. Though you’d be hard-pressed to find a person who doesn’t love this sticky-sweet condiment, syrup makers only have a short window of opportunity every year to produce this favorite flavor.
The fleeting sugaring season
Sugaring season begins with winter waning into spring, when the days get warm, but the nights still sink below freezing. The daily freeze-thaw cycle is what pushes sweet sap out of the trees from which the syrup is made. As soon as nighttime temperatures rise above freezing and buds begin to grow on the trees, the sap becomes bitter and unusable, thus ending sugaring season as swiftly as it began.
Typically, sugaring season only lasts a few weeks or months, according to Discover New England. Every year is different, though. If winter should recede early, the season may begin early; if the weather warms up quickly, the season is cut short, Farming Magazine reported.
“We’re hoping for another good season [in 2017] where we get 3 weeks or a month of good cool sugar weather,” explained Burr Morse of Morse Farm Maple Sugarworks in Montpelier, Vermont, to Farming Magazine. “We had a season back in 2012 where we had a great week of sugaring around the first part of March. Then it turned to summer for 10 days and we lost our sugaring right there. That can happen and it’s nothing anyone can predict.”
Speeding up the sap production process
Given the unpredictability of springtime weather, it’s crucial that maple syrup producers make every moment count during sugaring season. Different producers approach this dilemma differently. One Vermont company, The Maple Guild, invented a steam-craft system that allows the company to produce 55 gallons of syrup in just three minutes using indirect heat, as opposed to the industry standard of an hour using direct heat, according to FoodNavigator-USA.
“Essentially, we pre-boil the syrup before it hits the main evaporators, and we do that with steam that was generated at the bottom evaporator – and we shoot air in to the top evaporator which makes the concentrate float in the steam,” explained Mike Argyelan, the CEO of The Maple Guild.
Other companies use sanitary shell and tube heat exchangers to both pasteurize the syrup and make it less viscous and easier to bottle. Putting the product through this process also removes any insects or other contaminants that have a way of getting stuck in the sticky sap.
Another technique is reverse osmosis, a process by which maple sap is concentrated before entering the evaporator where it becomes syrup. A research paper detailing experiments with RO on maple sap conducted at the University of Vermont Proctor Maple Research Center stated that this method can decrease the amount of time syrup spends in the evaporator, increasing both productivity and energy efficiency. Researchers compared the effects of concentrating the sap to 2, 8, 12, 15 and 21.5 percent sugar concentration and found that flavor, color and other characteristics were generally consistent across the board. ONMapleSyrup noted that by using RO, producers can reduce the number of taps needed to manufacture their syrup.
In addition to saving time and taps, RO also reduces the need for fuel, making the syrup production process more environmentally friendly.
Saving energy during syrup production
Since syrup production is consolidated into a several-week-long sprint, condensed operations demand high energy spend. While more syrup producers are utilizing RO technology, there are other ways producers can save energy.
A large amount of water needs to be removed from sap to make syrup. Because of this, the syrup-making process gives off incredible amounts of steam. The steam released provides a convenient and free heat source that producers are beginning to take advantage of.
“Syrup manufacturers can capture the heat lost to rising steam.”
A Forest Service Research Paper explained that by installing a shell and tube heat exchanger syrup manufacturers can capture the heat lost to rising steam and use it to preheat the sap before it reaches the evaporator. Like RO, this process will reduce the amount of time the sap needs to spend in the evaporator before it reaches the desired consistency.
This mechanism was perfected in 1974 by George Raithby of the University of Waterloo in Ontario. Prior to Raithby’s development, the use of any equipment above the evaporator would compromise the final product because rising steam would condense on the metal surface and drip back into the open pans of syrup. Raithby used a shell and tube heat exchanger with a drip pan installed beneath it to collect the condensate. Inside the tubes, the sap could be heated from a starting temperature of about 40 degrees Fahrenheit to around 190 degrees Fahrenheit before it reaches the evaporator.
The Forest Service conducted experiments to determine whether using a shell and tube heat exchanger to preheat the product would have any effect on the quality of the final bottle of syrup. The researchers found it did not, but pondered whether utilizing copper tubing instead of stainless steel would leave behind remnants of copper in the syrup. The researchers determined it did not after analyzing the ultimate product, though if producers are concerned about this effect, investing in a stainless steel shell and tube heat exchanger may be a smart move. Not only will it lend to consistent materials being used throughout the process, but it is also highly durable and long lasting.
Sugaring season, short and sweet though it may be, is an important time of year for maple syrup producers and, whether they realize it or not, breakfast lovers everywhere. If you’re wondering how a new shell and tube heat exchanger or a membrane can improve your operation, reach out to the engineers at Enerquip.