Although direct gas fired (DGF) ovens remain popular, they generally require more maintenance due to the significant number of burners. That’s why many oven experts, even DGF oven manufacturers, suggest turning to forced air or convection ovens to save cold, hard cash.
“Air blast furnaces are much more efficient in today’s environment than direct gas fired furnaces,” said Jerry Barnes, vice president of Babbco. “Air convection ovens can change temperature very quickly because you are using focused convection heating with powerful, high speed burners. You don’t rely on a hot box.
Additionally, these older radiant heat systems take much longer to heat up and cool down. Specifically, he noted, DGF ovens need 1 to 2 hours to preheat, while air-driven ones heat up in just 30 minutes.
“When you change products and change the baking profile of the oven, you reduce latency with convective heating because it can change air temperatures more quickly,” Mr Barnes said. “When you have a production slip, a typical oven will overheat and result in burnt edges on one part of the production cycle and light products on the other. Newer ovens, especially convection ovens, do not suffer from this flickering heat effect.
Ken Johnson, president of Gemini Bakery Equipment/KB Systems, also recommended considering an indirect gas oven because it uses approximately 30% less energy than a DGF. Energy is transferred to products more efficiently by convection than by radiant heat alone.
“Baking temperatures in convection zones are lower because of this more efficient heat transfer,” he added. “Gemini/W&P Turbulent Zones provide lower baking temperatures, lower energy consumption and more even baking.”
He said the zones feature evenly spaced carbon steel tubes that form the upper and lower heating plenums of the furnace. A mesh belt support grid is located at the top of the lower tubular chamber. The heating gases then pass through the tube plenums and emit energy into the baking chamber. The recirculated air in the roasting chamber passes through the gap between these discharge pipes. Additionally, this variable speed airflow is reversible and can be top-down or bottom-up for different products.
Since introducing convection ovens more than a decade ago, Auto-Bake has converted many of its older hot-oil ovens to convection, noted Scott McCulley, president of Auto-Bake Serpentine and Hinds-Bock, both part of the Middleby Bakery Group.
“Generally speaking, cake makers are reluctant to use convection heating because it causes the product to crack and cause problems with the crust,” Mr McCulley said. “Because of the way we can control the top and bottom convection, we can virtually eliminate all the airflow from the top of the product that causes these problems and produce a much better product than a radiant oven. They can cook the product faster, and instead of raising the temperature to drive the heat into the product, we can lower the temperature and speed up the fan and use the fan as a mechanical force to drive the heat into the pans.”
Marie Laisne, product marketing manager at Mecatherm, said the company’s M-TA can offer multiple heat transfer modes, such as convection, radiant heat or a combination of the two in each independent heating zone.
“Providing the exact amount of energy required for the minimum baking time to reach the required product quality criteria, this oven offers an optimal solution for energy consumption,” she said.
Mr. Johnson indicated that Gemini/W&P provides an oven with radiant heat only, some zones with a combination of radiant/turbulent/convection heating, or all zones with a combination of radiant/turbulent/convection heating. Turbulent zones are available with two or four fans for enhanced convection.
Mr Barnes said hybrid ovens had been around for decades and compared their versatility to a Swiss Army knife.
“Hybrid ovens give you multiple tools in your pocket to deploy based on the product, which helps future-proof the oven,” he noted. “In today’s market, manufacturers have to adapt very quickly to consumer tastes.”
Joe Zaleski, president of Reading Bakery Systems, said DGF ovens bake primarily with low radiation and convection air currents. The product is developed and baked in a quiet and humid environment. Mix and match technology allows bakeries to tailor the baking profile to enhance the characteristics of specific products.
“Many hybrid ovens use this very gentle heat to create the texture and flavor profiles of their products in the front zones of the oven and change to a much more aggressive, higher airflow environment in the back zones of the oven to dry out the the product to final moisture. content,” Mr. Zaleski explained. “Convection energy is more effective in this drying area because the heated air is forced directly onto the product, providing moisture reduction with both heat and air.”
New technologies are also emerging. A few years ago, AMF Den Boer introduced the world’s first emission-free tunnel furnace running on hydrogen fuel. The Multibake VITA tunnel oven offers industrial bakers an effective solution to reduce carbon dioxide emissions by 99.9% in the baking process.
The modular oven uses green hydrogen, also known as pure hydrogen, a carbon neutral fuel. Although commercial ovens typically use natural gas as a heating resource, the company said this new patented technology will virtually eliminate carbon dioxide emissions from the oven while reducing utility costs.
For specialty bakeries that prefer rack ovens, Koenig Bakery Systems offers the Roto Passat SE with a potential of 20% energy savings.
Christian Benedict, group head, oven design, for Koenig said the ovens use a flow-optimized heating coil, high-quality sandwich insulation with an aluminum interlayer, and a continuously adjustable steam and control system to minimize energy consumption. In addition, the oven has a double-walled baking door made of duplex steel with rear ventilation for low surface temperatures.
He added that the increased energy efficiency can pay for itself in a year. A bakery operating six days a week, for example, can save about 4,000 liters of heating fuel, which corresponds to about 12 tons of carbon dioxide per year.
With energy prices showing no signs of abating, bakeries need to focus on maintaining ovens and exploring new technologies so they burn less and make more money.
This article is excerpted from the July 2022 issue of Baking & Snack. To read the entire feature on ovens, click here.