Pre-mix flame type burner

Abstract

A burner for burning a combustible gas comprising fuel gas and air that has been mixed before being supplied to the burner. The burner has a flame holder [concavely] axially and radially recessed into a flame outlet. The [concave] configuration of the flame holder focuses the individual flames on the combustion surface toward a central location where the individual flames interact with and reinforce one another in a direction axial to the burner. Thus very little heat is transmitted directly from the burner in a direction normal to the burner axis. This characteristic of the burner allows it to be used to fire a flue type heat exchangers where the walls of the heat exchanger are very close to the burner without excessive temperatures being produced in the heat exchanger walls adjacent the burner.

Description

BACKGROUND OF THE INVENTIONThis invention relates generally to burners for burning a combustible gas comprised of a mixture of fuel gas and air. More particularly, the invention relates to a burner of the pre-mix type where the mixing of the fuel gas and air has occurred before the combustible gas reaches the burner.Burners for burning a combustible gas find use in a wide variety of applications. One use is in hot air furnaces, where the burning gas heats air for the purpose of warming the interior of a building such as a house. In such a furnace, the burning gas and gases of combustion are confined with a heat exchanger, such as heat exchanger 50 in FIG. 1, while air to be heated passes over and around the exterior of the heat exchanger. Heat exchanger 50 is of the clamshell type and is typical of the heat exchangers found in residential warm air furnaces. Such a heat exchanger is manufactured by embossing two matching raised patterns into sheet metal and joining the embossed patte...

AI Technical Summary

Benefits of technology

The burner has a flame outlet having a flame holder .[.concavely.]..Iadd.which is axially and radially .Iaddend.recessed into the outlet. The .[.concavity.]. .Iadd.shape .Iaddend.of the flame holder causes the individual flames produced on the flame holder to be directed to a central focus, where they reinforce each other and combine to produce a flame that is projected along an axis normal to the plane of the flame outlet for some distance from the burner. In this way, the heat produced by the flame is distributed over a greater distance than is possible with prior art pre-mix burners. It is this distribution of heat in an extended flame downstream of the burner that allows the burner to be used with clamshell and tubular heat exchangers.

Problems solved by technology

The result is that the total length of flame from an inshot burner is relatively long.

The heat exchanger wall would necessarily be in close proximity to the burner and thus the concentration of the heat produced in the immediate vicinity of the burner would result in excessively high temperatures in the wall of the heat exchanger.

Such high temperatures would increase surface temperatures of the surrounding heat exchanger and shorten the life of the heat exchanger.

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