Abstract:
An oven that uses both impinging air ducts and infrared burners to heat food products is provided. Heating and cooking with both types of burners leads to a significantly improved efficiency over currently available systems. The infrared burner comprises a matrix of metal fibers that allows for the combustion flame to remain stable even when subject to the currents of nearby impinging air ducts within the oven cavity.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present disclosure claims the benefit of U.S. Provisional Patent Application No. 61/413,956, filed on Nov. 15, 2010. 
     
    
     BACKGROUND OF THE DISCLOSURE 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure relates to burners that are used in air impingement ovens. More particularly, the present disclosure relates to gas infrared burners that are used in conjunction with high velocity heated air to cook food products in an oven. 
         [0004]    2. Description of the Related Art 
         [0005]    Current commercial conveyor ovens use heated air forcefully directed at food products placed on the conveyor belt from both top and bottom to cook or heat the food product. Some ovens use infrared heaters to heat the product without high velocity air movement. Both methods of heating are effective. However, air impingement and infrared cooking give different tastes and textures to the food products being cooked. With infrared burners, high velocity air is typically not used, due to the effect of high velocity air interfering with the infrared burner&#39;s ability to produce a quality flame and/or infrared energy. Thus, there is a need to improve the efficiency of conveyor ovens while addressing these disadvantages. 
       SUMMARY OF THE DISCLOSURE 
       [0006]    The present disclosure provides gas infrared burner assemblies that are designed for use in an oven environment with high velocity air circulation. The burner assemblies comprise a burner surface made of layers or a matrix of small metal fibers. Combustion gases are fed to the burner surface and ignited, which allows the metal fibers to heat to infrared intensities. 
         [0007]    Thus, in one embodiment, the present disclosure provides an oven for heating food products, comprising an interior cavity having a longitudinal axis, a conveyor for carrying the food products along the longitudinal axis of the interior cavity, an impinging air duct that blows heated air onto the food products carried by the conveyor, and an infrared burner comprising a burner surface facing the food products on the conveyor. When the burner surface is heated, it heats the food products on the conveyor. 
         [0008]    In another embodiment, the present disclosure provides an infrared burner. The infrared burner comprises a burner surface comprising a porous matrix of metal fibers, a plenum connected to the burner surface, an inlet pipe in fluid communication with the plenum, wherein an air-gas mixture is introduced to the plenum through the inlet pipe, and an igniter, wherein the igniter ignites the air-gas mixture so that the ignited air-gas mixture surface heats the burner surface. 
         [0009]    In another embodiment, the present disclosure provides a method of cooking a food product within an oven. The method comprises the steps of passing the food product through an internal cavity of the oven, blowing heated convection air currents through an impinging air duct onto the food product, wherein the air impinging air duct is within the internal cavity, and simultaneously with the blowing step, heating the food product with an infrared burner, wherein the infrared burner is within the internal cavity. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  shows a perspective view of a burner assembly of the present disclosure; 
           [0011]      FIG. 2  shows a side plan view of the burner assembly of  FIG. 1 ; 
           [0012]      FIG. 3  shows an exploded view of the burner assembly of  FIG. 1 ; and 
           [0013]      FIG. 4  shows a side plan view of a conveyor oven utilizing the burner assembly of  FIG. 1  locating the IR burners in one of many possible locations within the oven cavity. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    Referring to  FIGS. 1-3 , burner assembly  10  is shown. Burner assembly  10  comprises burner surface  12 , igniter  13 , mounting plate  14 , clamping frame  16 , plenum  18 , and baffle  19 . A mixture of air and combustible gas is fed from pipe  20  into plenum  18 . Baffle  19  can assist with the even distribution of the air and gas mixture through plenum  18 . From there, the air and gas mixture is forced up through burner surface  12 , which is porous, and is ignited by igniter  13 . 
         [0015]    The design of burner assembly  10  allows it to be used in conjunction with impinging air ducts  30  in a conveyor oven  40 , as shown in  FIG. 4 . Burner assembly  10  heats a food product passing through oven  40  on conveyor  42 . There can be one or more burner assemblies  10  in an oven, on either side of conveyor  42 , and oven  40  can have one or more impinging air ducts  30 . Burner assemblies  10  can be placed in many possible locations within the oven cavity. Impinging air duct  30  delivers heated air to conveyor  42 , and any food product thereon, though an air plenum that can have one or more dispensing orifices (not shown). As discussed in greater detail below, burner assembly  10  can be used right alongside an impinging air duct  30 , without any adverse effects. The combined usage of infrared burner assemblies  10  and convection currents of heated air from ducts  30  presents increased flexibility, different food textures, and increased cooking speeds for oven  40 , which was previously not thought possible. Depending on the food items being cooked, any number of burner assemblies  10  may be used to impart the food quality and texture desired. 
         [0016]    Burner surface  12  is a layer or matrix of small metal fibers. Combustion takes place within the fiber matrix, and the flame is retained therein. As a result, burner assembly  10  provides combustion heat and infrared radiation to the oven environment, but is not subject to the disadvantages that typical infrared burners face when they are subjected to high velocity air flow. Burner surface  12  maintains the combustion flames within the matrix of small metal fibers, which allows the metal fibers to reach infrared intensities. Heat provided by the combustion process is forcibly directed towards the oven conveyor and the infrared energy provided by the heating of the metal fibers of the burner surface  12  enhances the cooking process. Examples of suitable products for the matrix of metal fibers in burner surface  12  include the D-Mat™, G-Mat™, and GFC-1™ fiber mats available from Micron Fiber-Tech, of Debary, Fla. 
         [0017]    It was previously not thought possible to achieve all of these advantages within the same oven. Typically, high velocity air from the impingement jets blowing onto an infrared burner surface would blow out the flame on the infrared burners and/or disturb or blow the flame off the infrared burner, rendering it ineffective. In some previous models, infrared burners were designed with air shields placed over the burner surface to protect them from the convection currents of adjacent air ducts. The shields, however, would be cooled off by the convection air flow, and/or never reach the infrared burner intensity, which dramatically reduced the efficiency of the infrared burner. Again, the present disclosure overcomes these problems. 
         [0018]    Burner assemblies  10  are designed to ignite and come up to infrared conditions in a short time (i.e., less than forty-five seconds) so that they can be turned off when not needed for energy conservation. Burner assemblies  10  can be turned on just prior to loading product on the conveyor  42 , and by the time the product reaches the area where the infrared energy is needed, burner assemblies  10  are operating with full infrared intensity. This provides a significant savings in energy consumption. 
         [0019]    The burner has been developed to be able to handle high velocity air directed at the burner surface and still achieve a high intensity infrared emission. The burner surface construction is critical to achieving high surface temperatures when subject to air being blown directly onto the burner surface. Ceramic tile burners, for example, cannot maintain surface temperature under these conditions. A burner surface  12  made of layers or a matrix of metal fibers that allow combustion and retain the flame within the outer layers of the material is required to achieve operation under the conditions found within an impingement oven. 
         [0020]    The air gas mixture that is supplied through pipe  20  into plenum  18  provides additional convection heating within oven  40 , as the air gas mixture will pass through burner surface  12 , and into the cavity of oven  40 . Furthermore, without being bound by theory, it is believed that the air gas mixture coming up through burner surface  12  provides enough pressure to ward off the convection air currents circulated by air ducts  30 . This pressure exiting burner surface  12  may prevent the convection air currents from blowing out the combustion flame within burner surface  12 . The physical characteristics (e.g., dimensions, porosity) of burner surface  12 , as well as the size of plenum  18 , and flow rate of the air gas mixture, all need to be adjusted to ensure that proper combustion occurs within burner surface  12 , and still prevents the convention currents from duct  30  from adversely affecting the combustion within burner surface  12 . 
         [0021]    While the instant disclosure has been described with reference to one or more particular embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope thereof. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated for carrying out this disclosure.