Digital systems along with strategic investments in new technology can keep bakeries from unwanted surprises and getting burned by rising fuel prices.
“Accurate recipe controls can help, along with idling the oven during gap conditions,” said Kevin Knott, technical sales manager, Bühler Group. “In addition, the installation of heat recovery systems are gaining popularity. Burner controls can be optimized to turn ribbon burners on or off if not needed, particularly during gaps in production.”
Jerry Barnes, vice president, Babbco, pointed out that traditional, direct gas-fired (DGF) ovens require a steady load of products so optimizing production scheduling and minimizing gaps will lead to efficiency. Gap-sensing strategies using adaptive control recognize when an oven zone is empty. Updated control panels and use of direct-spark ignition, which cost $80,000 to $100,000 plus installation, often provide a short-term option until replacing an old oven.
Ken Johnson, president, Gemini Bakery Equipment/KB Systems, said digital controls with menu parameters can optimize oven settings for each product and provide a high degree of repeatability. Automating heat dampers, linear actuators and steam valves will lower energy usage during oven idle periods while gap controls reduce flash heat that can burn products.
“Run-time programming can alert the baker to preventive maintenance, tuning, inspection and cleaning requirements to keep the oven functioning as efficiently as possible,” he said.
Joe Zaleski, president of Reading Bakery Systems, suggested that downtime software can slash fuel consumption by automatically setting the exhaust dampers to a minimum, lowering the belt speed to the slowest setting and forcing all burners to the minimum firing rate. It can also turn off burners if the divider or dough cutting system on the production line stops.
“When additional dough is loaded in the hopper after a shutdown period, the extrusion or sheeting process can trigger the restoration of all production settings,” he said.
To minimize the fresh air entry in the oven during baking operations, Mecatherm developed a new oven feature that helps bakers manage the damper opening settings and limit excess energy consumption.
Marie Laisne, product marketing manager at Mecatherm, said the digital control evaluates the exact quantity of extracted flow and allows operators to adjust settings to optimize energy consumption.
Most ovens also come with modulating burners to optimize baking conditions and adjust to variations in product load to avoid unnecessary overheating. For instance, reducing burner temperatures from 350°C (660˚F) to 150°C (300˚F) cuts energy loss by 40%, Ms. Laisne said.
Even the best digital controls cannot compensate for not-so-good manufacturing practices and lack of maintenance.
Scott McCally, president of Auto-Bake Serpentine and Hinds-Bock, both part of Middleby Bakery Group, said many bakeries set the exhaust fan at one speed and run it constantly, even when the burners are at low fire.
“Many bakers may have problems relighting the burners consistently, so they’ll leave the burners on and waste fuel,” he observed.
Mr. McCally said bakers also waste energy when they run their burners with a rich fuel-oxygen mix to keep them lit. Digital controls can adjust gas-oxygen ratios as the burners modulate to keep the oven from overheating, but that only works if maintenance personnel tune the burners correctly.
For many baked goods, tracking humidity can assist with oven efficiency and product consistency. Higher humidity levels can save energy because a moist environment holds more heat than dry air. Products like hamburger buns retain their softness with the proper humidity.
Middleby Bakery uses an oxygen displacement sensor that monitors and adjusts the amount of oxygen in the oven compared with the amount of moisture in the box.
“It’s automatically taking those inputs and controlling the output fan speed to modulate and hold the humidity at a constant level,” Mr. McCally said. “As you add more product in, you’re building up more moisture so if you want to hold the humidity at 20%, the fan will speed up to keep it at 20%. If there is a gap or the oven becomes less full, the fan will slow down.”
Cookies, crackers and snacks, however, tend to benefit from drier environments. Mr. Zaleski suggested reducing water in the dough formula, if possible, to have less moisture to remove in the oven.
Moreover, he said, measure humidity in each oven zone to determine if the exhaust volume can be reduced to save energy on reheating the makeup air.
This article is an excerpt from the July 2022 issue of Baking & Snack. To read the entire feature on Ovens, click here.