| 摘要 |
PROBLEM TO BE SOLVED: To provide a low NOx emission and improve a thermal efficiency by a method wherein a row of flame holes are, arranged at a wall surface of a burner main body, pre-mixed gas having air less than a specified value of a theoretical combustion air volume is injected out of the flame holes, a shielding plate for closing a lower part of a space is arranged, and its opening or closing may easily be carried out. SOLUTION: Either a number of vertical slits or a plurality of flame holes 3 are arranged at an upper part of an inner circumferential wall of a horizontal ring-shaped burner main body 1. Then, a shielding plate 4 for use in closing an air blowing-off space 2 at the central part of the burner is arranged below the flame holes 3, a concave part A is formed at the central part of the burner main body 1. A mixing ratio of primary air is adjusted in such a way that the pre-mixed gas having an air volume approximate to a theoretical value to low pressure gas such as municipal gas or the like (less than±30% of the theoretical combustion air volume, for example) may be infected out of the flame holes 3. In addition, the shielding plate 4 is formed in such a way that it may be freely rotated, opened or closed, its opening or closing operation is set to be cooperatively operated with a gas plug 5 under an operation of a cooperating mechanism 6.
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