Among the known radiation type burners are the metallic burner using a wire net adapted to be red-heated by the combustion of gas taking place over its surface, and the ceramic burner in the form of a ceramic plate formed with gas passages. In the case of the metallic burner, from the standpoint of the corrosion resistance of metals at high temperature, it is difficult to increase the combustion surface temperature to provide increased heat radiation. On the other hand, the ceramic burner plate, the material of which is highly resistant to heat, is capable of having its surface heated to a relatively high temperature, but if its surface is heated to 900.degree. C. or above, the back-surface temperature would also become high as to cause a backfire. Raising the burner plate surface temperature is also undesirable in that the thermal shock due to the ignition and flame-out of the burner increases so much as to cause cracking, the cracked portion, in turn, tending to cause backfire, which shortens the life of the plate. To remedy such drawbacks, attempts have heretofore been made to use ceramic cloth for the combustion surface or use porous ceramics as a plate material of low thermal conductivity for the burner portion. Another attempt has been to irregularly deform the combustion surface to obtain a burner plate having a larger surface area, but it has a drawback that the deformation of the combustion surface results in dark portions representing poor combustion of gas, increasing the CO/CO.sub.2 ratio of exhaust gases.
USPTO Backgrounds
USPTO Backgrounds