Tunnel/Band/Traveling Hearth Oven – Continuous
Industry: Bakeries and Tortilla Manufacturing (NAICS 3118)
Process Brief: Dough is heated to produce bread, cookies, and other baked products.
Energy source: Usually gas, but can be gas and oil
Energy Intensity: 400-2000 Btu/lb
The tunnel oven is another type of continuous baking oven. It is also known as a traveling hearth or band oven. In a tunnel oven, the hearth is a motorized conveyor that passes in a straight line through a series of heating zones. Loading and unloading occur at opposite ends of the tunnel, and oven capacity can range from 5,000 to 10,000 pounds of bread per hour. Despite a higher initial cost than traveling tray ovens of similar capacity, tunnel ovens offer many advantages. The long, flat hearth has unlimited flexibility with respect to pan sizes; the oven has easy and accurate top and bottom heat control; there is no problem of tray stabilization; steam conditions are close to ideal; and temperature control is simple, responsive, and accurate. Tunnel ovens are used exclusively in the cookie and cracker industry, with the product being deposited directly onto the conveyor band. These bands may be solid steel, perforated steel, or wire-mesh bands.
Tunnel ovens are designed for very large, fully automated, continuous processes. The product is placed on a conveyor that moves it from assembly through baking to cooling and packaging. The tunnel oven is used in large bakeries and to make large volume products such as cereals and pet foods. Tunnel ovens can use direct-fired convection heating, indirect-fired heating and in some cases, radiant heating if a browning or crisping enhancement section is needed. Tunnel ovens may also have steam injection for controlling moisture during the baking process. Steam alone may be used in some lower temperature baking processes.
Tunnel ovens are rated in the millions of BTUs and likely will have multiple gas burners. When getting the gas ratings of tunnel ovens, be sure that you have identified all of the gas burners.
445 Paramount Drive
Raynham, MA 02767
This site has lots of pictures and information about various large tunnel ovens, and other large scale baking equipment for industrial process sized facilities.
2057 East Aurora Rd.
Twinsburg, OH 44087
This site has smaller baking equipment more applicable to large bakeries.