Low temps, high demands
May 1, 2014
by Ryan Atkinson
The pressure can come from anywhere. Whether it’s fueled by regulations, the need to appeal to earth-friendly customers or the simple idea of cutting costs and boosting efficiency, bakers are searching for more ways to become green in more ways than one.
Naturally, that search leads to suppliers, who are asked to provide bakers with the latest advances to comply with such requests. Suppliers of refrigeration and freezing lines are no different.
Smart Watt Energy, Inc., Ballston Lake, NY, is a turnkey energy services contractor that works with a number of baking companies, among others.
“Our customers are wanting to become more sustainable,” said Bryan Genevick, Smart Watt’s director of multi measure. “The pressure is related to reducing operational costs and having a positive impact on the environment.”
High cost of freezing
When the question is raised of what accounts for the highest costs associated with running a freezer in a bakery environment, the answer is fairly consistent: the energy-consuming compressor and the gasses being used to chill the air and product.
“Compressors are the largest consumer of energy in these systems,” Mr. Genevick said. “One strategy to counter this is to shift energy load consumption off the compressors to other equipment that operates more efficiently. And you can simply embrace newer technologies in refrigeration equipment.”
Ed Cordiano, program manager for bakery and prepared foods at Linde North America, Murray Hill, NJ, pointed out the high cost of gasses used in cryogenic freezers.
“When it comes down to it, it’s the efficiency of the cryogen that is being used for the chilling,” Mr. Cordiano said. “It can quickly cause the freezing cost per pound or per piece to escalate. Even more than the price of the cryogen, it’s the way in which it is being used. It starts with the way the system is designed and engineered. We go in with our engineering team and design the system from the ground up for a sustainable freezing and chilling operation.”
Cool approaches for freezing
Perhaps the most obvious route to better sustainability is simply reducing energy during a product’s journey from formation through freezing. Of course, that’s usually easier said than done. Consider what’s happening with the design of cryogenic technology, which uses ultra-cold gasses to freeze foods.
One way Linde has found to bolster system efficiency is to improve the way the cold air flows across and around the product. This approach cuts the amount of liquid nitrogen cryogen required and is demonstrated by Linde’s Cryoline XF cryogenic spiral freezer.
“With its design, the thing this freezer does better than anything is give an even air flow distribution across the belt width,” Mr. Cordiano said. “In doing that, it creates a consistency in product temperature.” That increased uniformity in temperature translates into a bump of efficiency for the customer.
“That means you’re going to improve your product quality and consistency, no matter where that product lines up on the belt,” Mr. Cordiano said. “We’ve seen efficiency improvements in the 10% range.”
Praxair, Danbury, CT, streamlined the freezing process by focusing on the delivery of cryogens during the freezing process. “Cryogenic freezing has always had a perception of being more expensive,” said Phil Davis, Praxair’s associate director of marketing communications. “It had to do with people not necessarily using the cryogen correctly.”
The company honed in on the delivery aspect and helped customers grasp a better understanding of how to work with the gasses and apply them to the product.
“We worked with our processors and our equipment folks to look at ways to deliver the cryogen more effectively within the tunnel, increasing the performance,” Mr. Davis said. “That allows us to direct the cold to the product as opposed to it being wasted and not used properly.”
When it comes to mechanical systems, where freezing is done by air blasted at high speeds through refrigerated coils, the matter of defrosting those coils has long harbored hidden costs. Cold air circulating through the freezer picks up moisture from the warm products, moisture that ends up freezing to the coils. As refrigerated coils become clogged with frost, their efficiency diminishes, so coils must be shut down periodically for defrosting and cleaning.
Despite the operating limitations of sequential defrosting, Peter White, president and CEO of IJ White, Farmingdale, NY, said this system works, which is why it is still in use. His company, however, has found ways to improve on it.
“Sequential defrosting allows you to run for long periods of time without stopping,” he said. “You’re saving some energy with that basic, traditional sequential defrost because you’re running continuously.”
The problem, Mr. White said, comes with the heat needed to defrost the coil. “Every time you go into defrost, you’re using a lot of energy,” he said. “You’ve got to bring the heat into the coil and melt the frost, ice and snow on that coil. People didn’t really care how frequently the cycling of the defrost was. It just worked.”
IJ White studied this process, specifically the time needed between the defrosting of coils. This led to the design of its Extended Production Systems with Advanced Defrost Control.
“This allows coils to handle a lot more snow and ice before they have to go into defrost,” Mr. White said. “The coils can run longer. So instead of defrosting coils every five or six hours, we’ve almost doubled service time to eight or 10 hours. Every time you do one less defrost, you save all that heat and energy.”
At times, some of the best ways to ensure sustainability involve physical changes. Some of those changes turn out to be relatively simple.
“Most recently, we added to [efficiency] by making a physical change, relying on, believe it or not, gravity,” Mr. Davis said of recent improvements made by Praxair.
The air inside a bakery’s production shop is warm and moist, obviously not the ideal environment when trying to freeze product. Cryogenic systems typically are installed on the production shop floor. When that warm, moist air seeps into the freezing system, it requires more energy and more cryogen to complete the job.
“By reorienting the tunnel, we actually tipped up the ends of its entrance and exit. This doesn’t allow the infiltration of that room air into the tunnel,” Mr. Davis said. “That’s a physical barrier to keep the hot and moist air out; therefore, the cryogens and the product inside are not dealing with the warmer air temperature.”
At Linde, meanwhile, a simple change in the shape of the freezer now creates a spike in efficiency. “If you look at the way spirals have been developed and created in the past, in essence it’s a stainless steel box,” Mr. Cordiano said. “That’s a traditional cryogenic spiral, and we do still manufacture those.”
But with Linde’s new cross-flow spiral, that shape has shifted.
Mr. Cordiano called it “a radical redesign of a spiral freezer from the ground up.”
“We’ve actually formed the shell of the freezer so it wraps tightly around the belt. It’s not a cube,” he explained. “The middle of it is cylindrical in shape. It literally wraps right around the belt.”
Not only does the design reduce the amount of space that needs to be chilled, but it also requires less material to manufacture. That can go a long way in sustainability efforts and can reduce cost. “We’re able to use about 50% less stainless steel than a comparable spiral rated for the same production in a traditional cryogenic spiral,” Mr. Cordiano said.
At IJ White, more focus on the refrigeration coils has helped in reducing the amount of energy needed during defrost.
Traditionally, when coils are warmed to melt accumulated ice and frost, some of that heat moves throughout the system. This requires more power to hold the base temperature low enough to keep the freezing process on track.
That’s where IJ White’s coil isolation technology enters the picture. “Basically, that seals the coil off and keeps that heat from going into the process area,” Mr. White said. “We’re locking that coil down and isolating it, and that has been a noticeable energy saver.”
Culture and perception
Sustainability can help suppliers and bakers move toward less energy usage and better profits. Outside of directly impacting a company’s bottom line, however, a focus on sustainability can have a positive effect on business perception.
Mr. Genevick related a story told to him by one of Smart Watt’s customers. During a job interview, a candidate inquired about the progressive nature of the company and whether or not it was trying to advance its technology to protect the environment.
“The hiring manager said he didn’t really have a solid answer at the time,” Mr. Genevick said. “So the candidate said the company was not for him at that time, got up and left the interview.”
That inability to address sustainability, Mr. Genevick said, cost the company a shot at hiring an employee. “That illustrates that culture and perception now play a big part in the decisions surrounding energy savings and sustainability,” he said. “It addition to reducing operational costs, it’s also important to be able to show that you are trying to do things in more efficient way.”