The Really New Science of Ovens
October 1, 2010
by Shane Whitaker
Rising fuel costs and bakers’ desires to achieve more sustainable operations have prompted oven manufacturers to redesign their industrial ovens. Today, bakers monitor gas and electrical consumption of ovens more closely, and once they establish a benchmark, they likely will look for ways to bake more products using less energy.
For example, cutting-edge nanotechnology systems now exist that will help to increase capacity by 10% and reduce energy consumption by 20%. Others are using heatrecovery systems, and one burner manufacturer also introduced a new complete energy management system that recovers not only heat but also ethanol and puts it back into the gas stream used to fuel the oven, thus eliminating the need for the oxidizer on the exhaust stack.
This is a revolutionary time for industrial baking ovens, which can now offer everything from heat and energy recovery systems to greater control features to reduced installation times.
To make its ovens more energy efficient, C.H. Babb Co. provides recirculated air, heat recovery and exhaust control systems, according to Charles Foran, president of the Raynham, MA-based company. “Typically, our air impingement ovens offer a faster, more efficient bake, which leads to increased production and lower emissions,” he said. “Using green technology, our recirculated air ovens can provide 30 to 50% in fuel savings when compared with other style ovens.”
Reading Bakery Systems (RBS) showcased its heat recovery system at the 2010 International Baking Industry Exposition (IBIE). Its system is designed to add preheated makeup air in the penthouse where a burner normally heats air going into the oven. “By bringing in preheated air, we can reduce the requirement of the burner in that penthouse,” said Shawn Moye, executive director of sales, RBS, Robesonia, PA. “Instead of bringing in cold air that has to be heated up to 500°F, you are bringing in 200 to 250°F air that only has to be heated to 500°F.”
The oven manufacturer can provide these heat recovery packages on its new ovens. “We have been working with heat recovery for years, but development has come along, and we are now offering this as a package with our new ovens,” he added.
AMF Bakery Systems, Richmond, VA, recently upgraded designs for its Vesta 38 direct-fired traveling tray and Vesta DF direct-fired tunnel ovens. The changes achieve a more even bake and higher energy effi ciency, while offering greater value to the baker, according to Phil Domenicucci, thermal product manager. “AMF commissioned a scientific study of airflows and determined the optimal design for our new convection systems,” he said. “This allows the complete system to be used for all products and, in addition, permits the baker to easily adjust nozzles from outside the oven.”
Mr. Domenicucci pointed out that these changes can result in major energy savings. “We found that conventional color-aider systems had significant airflow restrictions, which caused in an uneven flow of air through the ducts,” he observed. “By using the latest in computeraided engineering (CAE), new ducts were designed, resulting significant airflow improvements along with a reduction in the number different parts needed.”
AMF also used CAE to design the heat distribution system for its Vesta IF indirect-fired mesh-belt tunnel oven, which provides an even bake, especially for highsugar products. “The Vesta IF oven is designed for greater energy efficiency, extremely even baking and ease of maintenance,” Mr. Domenicucci added.
Perhaps AMF’s biggest breakthrough technology displayed during last month’s Baking Expo was its Emisshield system that takes advantage of nanotechnology to broaden infrared reflectivity inside the oven. The nano-emissive particles, which were developed by NASA, increase oven thermal capacity by up to 10% and reduce gas usage by 20%, according to Mr. Domenicucci.
The technology has been applied in the petrochemical, steel and glass industries, but AMF has a patent pending for use of this technology for bakery products, Mr. Domenicucci noted.
The technology delivers extra radiant heat and enables a more even bake. “Volume, crust and crumb quality all are improved for products that are baked in ovens with Emisshield,” he said.
Additionally, gas combustion is more complete in the presence of Emisshield. As a result, fewer emissions and possibly less volatile organic compounds (VOCs) occur, Mr. Domenicucci said. “Where it has been used, it has greatly reduced harmful emissions and, in some cases, eliminated the need for oxidizers,” he added.
The technology is available on new AMF ovens, and in the near future, older ovens can be retrofitted with Emisshield, according to Tim Cook, AMF’s vice-president of sales, marketing and product management.
ERB CORE, a division of the Ensign Group, Pelham, NY, introduced its new Condenser Oxidizer Recuperative Exchanger (CORE) system at IBIE. This technology can assist bakeries in reducing fuel consumption up to 50%, said John Cavallo, c.e.o. of the Ensign Group.
The CORE system recaptures ethanol produced during the baking process as a by-product of yeast fermentation and reintroduces it into the gas stream to
help fuel the oven. “We are able to use ethanol as a complementary biofuel that we can directly put to use in the oven,” said Jim Pezzuto, president, of ERB CORE.
The newly developed energy recovery system with the proprietary ethanol recovery block eliminates the need for stack oxidizers traditionally used to burn-off ethanol and other VOCs created during the baking process.
CORE also features an evaporative water recovery unit that recaptures water from the water vapor in the oven stack gases and provides the bakery with the recycled hot water for washing service and steam for the proofer, Mr. Cavallo noted.
The 50% fuel savings achieved with the system results from a combination of the fuel saved by preheating combustion air and the reduction in proofer energy consumption, along with the ethanol being used to fuel the oven and the fuel previously needed for oxidizers and process boilers. Consequently, CORE dramatically reduces the carbon footprint of the bakery.
The only by-product of the process is carbon dioxide, which has a temperature of less than 85°F when it is released into the atmosphere. “The next step is taking that CO2 and piping it to a greenhouse,” Mr. Cavallo quipped.
Baking Technology Systems, Inc. (BakeTech), Tucker, GA, now offers a color imaging system that performs quality control analysis on buns at the exit of its ovens. The imaging system automatically adjusts the oven controls accordingly. Geri Walker, president of BakeTech, said the company received a grant from the state of Georgia and worked with the Georgia Institute of Technology and Flowers Foods, Thomasville, GA, to develop the quality control system.
“What happens with any fermentation system is that you have a front end and back end to each batch of dough, and we can see with the vision system that buns made from the same batch go from darker to lighter over time. With a 20-minute mix, you could see a 20-minute cycle [in coloration] coming out of the oven. The idea was to straight-line that and eliminate the color variation from the start of the batch to its end.”
BakeTech builds continuous ovens, which, according to Mr. Walker, have become fairly standard for the baking of fast food buns. Its ovens offer full zone control, including separate control of top and bottom recirculation air. A PLC with touch-screen interface allows the baker to create different set points for each of these parameters.
Humidity control helps to give ovens the same atmosphere whether it is a wet day or a dry day, Mr. Walker said. “The air in the bakery, the combustion air that is being pulled into the oven — all of it varies in humidity, and our humidity control manages the damper and maintains a consistent level,” he said. “That is unique to BakeTech.”
BakeTech’s continuous ovens are already energy effi - cient compared with tray and tunnel ovens, according to Mr. Walker. “You don’t have all that metal to heat up, and you don’t have big openings through which heat can escape,” he explained as the reasons why continuous ovens are naturally more energy effi cient.
“Companies that put in continuous ovens tell us how much less fuel they are using,” he added, noting that such ovens use approximately one-third less energy than a tray oven and about one-half the energy that the typical tunnel oven.
Complete PLC management systems, according Mr. Foran, are an emerging technology for ovens. “A high-end management system can include items such as custom reporting, increased data storage for trending, downtime analysis and images for individual recipes to help the operator achieve the target product, along with access to the equipment manual through the human-machine interface,” he said.
Turkington USA unveiled the the next evolution of its 960 tunnel oven at IBIE. Developed to answer the latest market needs in flexibility and energy effi ciency, the oven maintains the robust design characteristics of a proven heritage. “We are laying out an oven process control (OPC) system that allows a customer to select from very basic oven control when doing very long continu- ous runs, or at the other extreme, if a customer is baking a lot of varieties, it offers management controls to assist with quick changeovers,” according to Jerry Barnes, vicepresident of engineering, Turkington USA, Clayton, NC.
The 4-tiered control package offers a new high-end system known as eBake, which the company describes with the tagline “revealing the science behind the art.” “A number of customers are asking us to help them understand more of the actual science behind baking, so for us that means monitoring a lot more of the key parameters that go on within the oven and, to whatever effect that we can, provide some ability to control that,” Mr. Barnes said. “The new control system put these parameters upfront so the customer can highlight process and quality issues in a more real-time fashion rather than discover issues much later at the slicers.”
AMF VestaGuard advanced monitoring and control system was designed to provide value for the baker by offering easier operation and maintenance. “For example, our chain monitoring system gives us a real-time monitoring tool that tracks the expansion of the oven chains and can tell what product is being baked and what the load is on the chain,” Mr. Domenicucci said. “It can also signal when the tensioning system is reacting unevenly. This reduces strain on the chain and extends chain life.” The control system also tracks energy consumption by offering a Btu-per-lb-baked analysis system.
Additionally, the baker can easily monitor all of the oven’s burners with VestaGuard Surefire Ignition System, and at a glance, he can see the state of all of the burners. “Coupled with opposite side sensing, DSI with distributed I/O, and plug and play components, the Surefire Ignition System provides a highly dependable user friendly design,” Mr. Domenicucci added.
The company also introduced the AMF Vesta/Artos conveyorized final proofer and oven at IBIE. “We looked at the market offerings and found areas that we could significantly improve the operation and add value to the oven,” Mr. Domenicucci stated. “Our most innovative design is the track. Most conveyorized final proofers and ovens require periodic replacement of the chain track, especially the curved sections. This is costly in material, labor and especially downtime.”
AMF’s patent-pending 2-piece curved track has outside and inside radius tracks. When installed, the outside radius is welded to the straight sections to eliminate any oil leaks. The inside radius has a bolt flange that matches the outside radius and also a wear strip on the inside to prevent the shear effect of the horizontal bearing against the track. “In the event the curve ever has to be replaced,” Mr. Domenicucci said, “all you have to do is relieve the tension on the chain, clamp the chain to the outside radius and unbolt and replace the inside radius — no cutting, grinding or welding.”
AMF also designed a redundant drive system for conveyorized ovens. “If you have to change-out a motor and gear box, all you have to do is just swap the chain,” Mr. Domenicucci explained. “The motor, gearbox, tensioner and sprockets are all in place and easily accessible from the top of the enclosure.”
Because each product requires a different amount of radiant, convection and conduction heating, RBS works to design each oven to best meet the needs of the customer and to provide the flexibility within that oven so that the baker or snack manufacturer is not limited to baking only one product in that oven, according to Mr. Moye. He said the company uses its Science and Innovation Center and Scorpion technology to design flexible ovens that meet its customer’s requirements.
“We provide flexibility in our ovens by providing optimal radiant, convection and conduction components, so we can move these thermal characteristics around for different products,” he said.
Also designed for product flexibility is an oven from BakeTech that steams bagels in the front section of the oven. “We got the best-looking bagels out of it,” said Mr. Walker, pointing out that the same oven could make either soft or chewy traditional bagels. Bakeries often demand flexible equipment, and such ovens can run hard rolls, bagels and soft rolls, he added.
RBS’s goal is to get ovens up and running quickly by completely prebuilding oven sections prior to delivery. “We just connect the sections with zone dividers, and they are off and running,” Mr. Moye noted. “It makes our oven installations very rapid.”
Turkington also greatly reduced installation times for the 960 oven. Mr. Barnes said that the time the company requires for installing and commissioning a new oven is about two-thirds of what was previously needed. “The modular design configuration gives us greater ability for preassembly at our shop floor,” he added.
Mr. Foran noted that some of the lastest design trends for ovens are stainless-steel washdown interiors and clean-inplace sanitation systems. Also, C.H. Babb’s fire prevention systems set it apart from others oven manufacturers, he added.
A lot is happening with regards to ovens for the baking industry. Innovations to industrial ovens will prove beneficial as bakeries seek improvement in product quality and reduction in their carbon footprints.