There’s no penny-saved, a-penny-earned when it comes to constantly heating 125-foot bread ovens or their 300-foot cookie and cracker counterparts.
Rather, the savings is a lot more. Instead of hearing the incessant pinging of coins dropping into a piggybank, the cost of energy efficiency for these industrial behemoths sounds more like C-notes quietly stacking up, one after another, as the production line remains running.
Think about it. On bread lines that crank out 200 units a minute, ovens can easily use 10 million Btus an hour. With the recent advances in oven technology, wholesale bakeries can better harness the hundreds of millions of Btus they use every day, even compared with an oven that had been installed just a decade or so ago.
“With our new ovens, we would expect to see at least 5-10% fuel savings as compared to older ovens,” said Tremaine Hartranft, director of technical services, Reading Bakery Systems (RBS).
Using forced convection technology, for instance, often results in 15% energy savings and 15% lower bake times, while employing heat recovery techniques that may save even 15% more, noted Kevin Knott, technical sales manager, Bühler-Hass.
“This fits with Buhler’s sustainability goals of 50% energy reduction,” he said. “We have developed several systems for heat recovery, for each zone and for the whole oven to recover heat for process water or to use for pre-heating the baking air.”
Energy efficiency may be a greater priority for many European bakeries where the cost of natural gas and electricity is considerably higher than in the United States. However, even North American bakeries driven by a competitive market and a need for cost control are exploring new systems and process enhancements. Many improvements are incremental, but together, could provide huge long-term savings.
“AMF is developing a new burner control system that will have dedicated burner air fans per section instead of having one central burner air blower for the entire oven,” said Remco Bijkerk, product group leader AMF Den Boer, a brand of AMF Bakery Systems. “This will lead to more accurate control and less use of air. It will lower energy consumption, in terms of kilowatt hours for electric and kilowatts for gas, and we estimate savings will be at least 3-5% of present total usage.”
Jerry Barnes, vice president, Babbco, pointed to the continuing developments in burner and gas train design that now provide for more precise increments in turndown ratio, or energy delivery.
“What this does is allow for better matching of heat output to the bake profile requirement,” he explained. “Enhanced control algorithms also exist today for managing production gaps and lowering oven gas usage when this occurs.”
On legacy systems that are 20 years or older, the ovens may operate adequately, but time takes its toll unless they’re properly maintained.
“First and foremost, it is important to target poor insulation because statistics show us that 10-15% of energy loss is due to this,” said Marie Laisne, marketing manager, products, Mecatherm.
RBS offers newer ovens that come with better insulation constructed from a dense mineral wool to maximize energy usage.
“The type of insulation selected can be very important to the oven’s efficiency,” Mr. Hartranft said. “At RBS, we pre-build our ovens to ensure the insulation is fitted tightly to the oven for maximum efficiency.”
Mecatherm also improves an oven’s performance by better managing its kinetic energy.
“If the oven can reach the desired temperature in a shorter time frame, then we can reduce downtime,” Ms. Laisne said. “Additionally, we can use modern burners that can be adjusted for a larger range while operating at a lower rate, thus avoiding frequent burner stoppages and restarts that generate overconsumption.”
She added that energy loss can also occur during loading and unloading of products. Another critical area involves adapting the oven to product demand.
“By providing easy access to HMI panels, we can balance the settings in each module, prevent parasitic air flows and limit energy losses,” Ms. Laisne observed. “Additionally, good humidity management inside the oven ensures the air transfers are smooth while protecting the integrity of the finished product.”
This article is an excerpt from the April 2021 issue of Baking & Snack. To read the entire feature on ovens, click here.