EP0158414B1

EP0158414B1 - Even flow radiant burner tip

Info

Publication number: EP0158414B1
Application number: EP19850301042
Authority: EP
Inventors: G. Richard Ogden
Original assignee: John Zink Co
Current assignee: John Zink Co LLC
Priority date: 1984-03-19
Filing date: 1985-02-18
Publication date: 1989-10-04
Also published as: JPH05606B2; EP0158414A2; DE3573463D1; EP0158414A3; CA1243937A; JPS60213715A

Description

The present invention concerns a burner which inspirates or educts air with gas to burn beyond openings at the end of a burner tube. In addition, the invention is applicable to a burner that uses forced air or forced air and gas for burning outside openings at the end of a burner tube. The outlet slots or openings must allow maximum emission of the gas-air mixture at sufficient velocity to prevent flashback into the burner tube.
It is to be understood that the invention is for use with a variety of gas-air, or air-gas mixing burners. For example, the invention includes burners using forced air pre-mixed with gas or alone, such as found in U.S. Patent No. 4,257,762, the invention being directed to the division of fluid flow at the downstream tip.
Additional prior art is found in FR-A-1 2342379 and FR-A-1233698. In the former the upstream flow is diverted through restricted openings and impinged against a baffle placing further restriction to the flow f₂. In the latter reference the upstream end of the flow divider and the created annular flow space is closed with the flow communication between space and the gas pipe is established by means of apertures in the flow divider.
It is an object of this invention to maintain efficient burning of radiant wall burner apparatus despite changes in velocity of the combustible gases and/or changes in types of fuel.
The invention provides a gas burner assembly for furnaces according to claim 1. A stream of high velocity fuel gas issues from an orifice to inspirate combustion supporting air into and mix with the air in a mixing section of a burner pipe. The burner pipe is inserted into an oversized opening through the wall of the furnace terminating at a downstream end adjacent and beyond the inner wall of the furnace. The inner wall of the furnace surrounding the furnace opening typically includes a radiant wall surface. The downstream end of the burner pipe is closed. A plurality of openings such as slots or holes are provided in the burner pipe adjacent the downstream end to project gas-air mixtures issuing therefrom, outwardly along the radiant furnace wall surface for burning. A flow divider comprised of an undersized cylindrical member is centrally located permanently or temporarily inside the burner tube adjacent the downstream end. The downstream end of the flow divider is oriented in close proximity to the inside periphery of the burner tube at said openings to effectively divide the openings into what is defined herein as a downstream flowing portion and an upstream flowing portion. The cylindrical flow-divider causes that portion of the fuel-air mixture which passes through the inside of the flow divider to be directed through the downstream portion of the openings. The remaining portion of the fuel-air mixture which passes through the annular space located between the flow divider and the burner tube flows through the upstream portion of the openings.
The invention will now be described further, by way of example, with reference to the accompanying drawings, in which:-

Fig. 1 is a partial sectional view describing the apparatus of this invention as it can be located in a furnace wall;
Fig. 2 is an enlarged sectional view of the tip of Fig. 1;
Figs. 3 and 4 depict other embodiments of the invention; and
Figs. 5,6 and 7 depict other forms of flow divider baffles within the scope of the invention.

The burner assembly of Figs. 1 and 2, generally designated by the numeral 10, is inserted through an opening 12 formed as a part of a burner block 14 located through a furnace wall 16. The basic gas-air mixing burner assembly shown here is merely typical, as the invention is not to be limited to that type shown. The burner assembly is supported by a mounting plate 18 as by welding or bolting to plates 20 and/or 22. The mounting plate centrally supports a burner tube 30 and includes openings which may be regulated for the flow of secondary air as shown. Centering lugs 32 are provided in the annular space between the burner tube and the mounting thimble or plate 20. By supplying gas into an aspirator section 36 primary air, from a muffler 37, is caused to be inspirated at 38 into the burner tube 30 where it is mixed with the gas and thence caused to issue from the downstream end 40.
A conical shaped plug 42 typically closes the downstream end. A plurality of spaced openings or slots 44 are provided around the circumference of the downstream end of the burner tube 30. These openings 44 project gas and air essentially outwardly for burning along the furnace wall and a tile surface 46 which is capable of providing additional radiant heat energy to the interior of the furnace as is known in the art. The invention is particularly directed to a flow divider 50 which is provided in the interior of the burner tube, adjacent the downstream end. The flow divider is comprised of a cylinder which includes outwardly projecting lugs or feet 52 which centralize the flow divider in the position shown. Other forms of centralizer means such as protrusions from the body of the cylinder and the like can be provided. The flow divider can be permanently installed as by welding in a centralized position. The downstream end of the flow divider is caused to be oriented in close proximity to the inside periphery of the burner tube at the openings, thus dividing the openings into a downstream flow 54 and an upstream flow 56.
In Fig. 3 a straight burner tube 60 is depicted having an end closure 62 and a plurality of slots 64 disposed inside the tip. In this embodiment the flow divider 66 is disposed about the tip. In this embodiment the flow divider 66 with its centralizing members 68 is shown. Likewise, in.Fig. 4 the primary distinction is the use of a burner tube 70, which may be straight or curved as shown, having an end closure 72 and a plurality of holes 74 surrounding the tip. The flow divider 76 with its centralizing members 78 is shown positioned with respect to that embodiment.
Figs. 5, 6 and 7 depict different forms of flow dividers, such as an angularly inclined member 84 dividing slots 82 of Fig. 5, a right angle divider 86 dividing slots 88 of Fig. 6 and a beveled flow divider 90 dividing slots 92 of Fig. 7.

Claims

1. A gas burner assembly for furnaces wherein a fluid stream of pre-mixed fuel and aspirated combustion supporting airflows axially through a burner pipe (30), the burner pipe (30) being inserted into an oversized opening (12) through a wall (16) of the furnace forming an annulus for the passage of secondary air therethrough, a downstream end of the burner pipe being closed, a plurality of circumferentially spaced openings (44) in the burner pipe (30) adjacent the downstream end being adapted to project the fluid stream issuing therefrom outwardly to intersect the secondary air for burning along a radiant furnace wall surface surrounding the burner pipe, a flow divider (50) for the premixed fuel and air being centrally positioned inside of the burner pipe at the downstream end, characterized in that the flow divider (50) comprises a thin walled metallic cylindrical member of length substantially less than the length of the burner pipe, the upstream end of the flow divider (50) being of lesser diameter than the burner pipe forming a substantially undivided annular flow space between the cylindrical member and the .inside diameter of the burner pipe and an undivided inside central space, the cross-sectional area of the annular flow space being less than the cross-sectional area of the inside central space, the downstream end of the flow divider (50) flaring outwardly so as to be contiguous with the inner periphery of the burner pipe opposite the openings (44) to divide the fluid stream through openings (44) into a downstream and an upstream portion whereby a first portion of the fluid stream passes through the inside central space of the flow divider (50) thence outwardly from the downstream portion of the openings (44) while the remaining portion of the fluid stream passes in an annulus between the flow divider (50) and burner tube (30) thence through the upstream portion of the openings (44).

2. A burner according to claim 1, characterized in that the downstream flaring outward portion of the flow divider contiguous with the openings has a curved surface.

3. A burner according to claim 1, characterized in that the downstream flaring outward portion of the flow divider contiguous with the openings has a tapered (84) or beveled (92) surface.

4. A burner according to claim 1, characterized in that the downstream flaring outward portion of the flow divider (86) contiguous with the openings is approximately perpendicular to the openings.