US3361185A

US3361185A - Gas burners

Info

Publication number: US3361185A
Application number: US542922A
Authority: US
Inventors: Anderson Robert Henry; Rann Cyril Henry
Original assignee: North Western Gas Board
Current assignee: North Western Gas Board; North Eastern Gas Board
Priority date: 1966-04-15
Filing date: 1966-04-15
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02

Description

Jam 9 R. H. ANDERSON ET AL 3,361,135

GAS BURNERS Filed April 15, 1966 v I '3 Sheets-Sheet 1 vINVENTOR:

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GAS BURNERS Filed April 15, 1966 3 Sheets-Sheet 2 mvzmon;

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Jan. 2; 1968 ANDERSOYN ET-AL I 3,361,185

GAS BURNERS Filed April 15, 1966 5 Sheets-Sheet 3 INVE NTOR:

ROBERT M ANDERSON c mm H- Ram hTT'olIIC Y United States Patent 3,361,185 GAS BUPNERS Robert Henry Anderson, Bradford, and Cyril Henry Rann, Bil-stall, Leeds, England, assignors to North Eastern Gas Board, Leeds, Yorkshire, England Filed Apr. 15, 1966, Ser. No. 542,922 6 Claims. (Cl. 158-75) ABSTRACT OF THE DISCLOSURE A nozzle for a gas-fired tunnel burner with a burner head having a series of air ducts and a series of gas ducts in nozzle-mixing outlets with one series of said outlets alternating with the other series thereof around a common pitch circle centered on a common axis of said inner and outer tubes, the gas jets diverging from the axis and their air jets converging thereon.

This invention relates to gas-fired tunnel burners of the nozzlennixing type capable of use in various circumstances as, for example, furnace heating or firing of radiant heat tubes.

The improvements concern a novel or improved con struction and assembly of the "burner parts aimed at producing advantages which will be mentioned hereinafter.

One object of the invention is to provide a burner which will give a particularly good mixing of the gas and air and consequently an efficient combustion over a considerable range of gas and air speeds.

Another object of the invention is to provide a burner of such a construction that it can easily be assembled and dismantled and also that it can easily be inserted in and removed from the furnace Wall, radiant tube or other structure in which it is mounted for operation. Such a form of construction facilitates inspection and replacement of the burner head without removing the whole of the burner mounting from its support structure.

A further object of the invention is to provide a burner which Will give a good flame stability and quick starting, both of which contribute to the efliciency of the burner and reduce the amount of attention it needs.

With these and other objects in view a burner according to this invention includes a body structure to support an outer tube Within which is an inner tube radially spaced therefrom, a burner head located at the inner end of the inner tube, an ignition device leading through said inner tube to said head, and means for passing gas and air separately through the body structure and respectively through said inner and outer tubes to two series of ducts in said head terminating in nozzle-mixing outlets at the nozzle face, these outlets being directed at an inclination to the axis of the head so that the gas jets diverge from said axis and the air jets converge thereon.

In the preferred construction the burner head is carried on the inner tube which is itself carried by a removable plate secured to the body structure, whereby the head can easily be removed with this tube for inspection or replacement. Preferably also a refractory tunnel is secured to the inner end of the tube assembly so as to project beyond the nozzle outlets and form a combustion space in which the flame is propagated.

In order that the invention may be fully and clearly comprehended, the same will now be described with reference to the accompanying drawings which are to be regarded merely as examples and in which:

FIGURE 1 is a longitudinal section through a burner assembly according to the invention fitted with recuperator fins and suitable for use with a radiant tube;

FIGURE 2 is an end elevation seen in the direction of arrow X in FIGURE 1;

FIGURE 3 is an enlarged longitudinal section through the burner head shown in FIGURE 1;

FIGURE 4 is an end elevation of the burner head seen in the direction of arrow Y in FIGURE 3;

FIGURE 5 shows a burner according to the invention mounted in a refractory block for insertion in the wall of a furnace; and

FIGURE 6 is a section taken on the line VI-VI in FIGURE 5 but omitting the burner head and tubes.

In the embodiment of the invention illustrated in FIG URES l to 4, a body 1 has an annular flange 2 by which it can be bolted to a corresponding flange 3 of a cylindrical radiant tube 4 part of which is indicated by chain lines. Into the interior of this body projects the boss 5 of a backplate 6 which is secured by bolts 7 to the body. Air is supplied through a union 8 to a segmental chamber 9 outside the boss 5, and gas is supplied through a union 10 and duct 11 to a central bore 12 in the boss. These unions are secured to the backplate 5 in which are also provided

tapping points

13, 14 communicating respectively with the bore 12 and the chamber 9 for checking the gas and air pressures.

An outer air tube 15 is screwed into the rear of the body 1 and an inner gas tube 16 is screwed into the boss 5, leaving an annular air flow space 17 between the two tubes.

Screwed on the end of the inner tube 16 is the sleeve 19 of a burner head 18. As shown more clearly in FIG- URES 3 and 4, this head has a series of gas ducts 20 spaced around its axis and leading from the interior of the sleeve 19 to the nozzle face, and a series of air ducts 21 similarly spaced but alternating with the ducts 20 and leading from the space 17 to the nozzle face. These two series of ducts are inclined in opposite directions to one another relative to the axis of the head and each duct lies in a plane in which the axis of the head lies, so that their outlets at the nozzle face lie on a common pitch circle. The result is to produce divergent streams of gas (indicated by full-line arrows with tails) and convergent streams of air (indicated by full-line arrows). Of course, these ducts need not be straight provided that their outlets are arranged to direct the gas and air jets as above described.

A collar 22 secured in the end of the outer tube receives and locates the burner head and has an annular bevelled face 23 to guide the head into position when the latter is passed along the outer tube 15 during assembly. The head makes a loose fit in the collar to allow for expansion and also to allow a small quantityof air to filter through. However, where the relative diameters of the head and the outer tube 15 permit it, the head may fit directly to the tube without the collar 22.

For the purpose of igniting the burner a spark plug probe 24 extends axially through the inner tube 16, its outer end being supported by a spark plug 25 screwed into the backplate 6. The probe is surrounded by insulation 26 and its inner end is supported by a porcelain insulator 27 in the burner head 18, leaving a slight gap through which a small quantity of gas can filter.

A refractory tube 28 is enclosed in .a metal tube 29 which is welded to the inner end of the air tube 15 or to the collar 22 so as to form a combustion space or tunnel 30.

0 tunnel 30 while the gas burns mainly around it and in contact with the tunnel wall, thereby transmitting a large proportion of its generated heat to the wall. This gives good flame stability. Eflicient combustion is also promoted by the air filtering between the head and the collar 22. Also good flame stability and quick starting on ignition is promoted by the gas filtering through the head past the probe.

It is to be understood that the number, size and angle or angles of inclination of the gas and air ducts in the head 18 will depend upon the circumstances in which the burner is to be used, e.g., upon desired volumes, speeds, temperatures and other considerations.

Also the above described construction of burner makes assembly and dismantling easy and it facilitates inspection and replacement of the burner head which can easily be withdrawn by removing the backplate carrying it.

The outer air tube has projecting radially outwards from it a series of longitudinal fins 31 forming with the burner an integral recuperator. These fins stop short of the body 1 which has in its upper part an ejector chamber 32X communicating with an upright flue pipe 32. Opposite this flue opening is an air jet ejector 33 fed by air from the interior of the body 1. By this means, when the burner is operating in a radiant tube 4, and the products of combustion are flowing back past the fins 31 to the flue pipe 32 to give up heat to the air passing along the space 17, as indicated by the brokenline arrows in FIGURE 1, the ejector action at the flue entrance promotes exhaustion of the products of combustion, and the ejector force is automatically controlled in accordance with the quantity (and therefore with the speed and pressure) of gas and air admitted to the burner. It will be understood that this admission of gas and air will be controlled by any suitable valve arrangement. The action of the ejector may be viewed through a sitehole having a closure plug 34.

Instead of fitting the burner with integral recuperator fins to enable it to be used with a single ended radiant tube as above described, it may be adapted for fitting in a hole in the wall of a furnace. This is shown in FIGURES 5 and 6 where the refractory tube 28X forming the combustion tunnel 30 is extended rearwardly to the body 1 and formed with longitudinal ducts leading into an annular space 36 which is located opposite to a flue outlet 37 formed in a refractory block 38 which can be let into the furnace wall. The whole burner assembly may be constructed as shown in FIGURE 1 but without the fins 31 and the flue outlet 32 and with or without provision for ejection.

This latter arangement may be used for a high temperature range, say 1000 C. to 1500 (1., whereas the arrangement shown in FIGURE 1 would be suitable for a low temperature range, say up to 1000 C.

Whilst the hereinbefore described embodiments of the invention have been mentioned merely by way of example, it is to be understood that other suitable embodiments may be evolved for carrying out the invention and that protection is hereby claimed for all such embodiments within the scope of the appended claims.

We claim:

1. In a gas-fired tunnel burner of the nozzle-mixing type the combination of a body structure, an outer tube supported by its outer end in said body structure, an inner tube located within said outer tube and radially spaced L1 therefrom and supported by its outer end in said body structure, a burner head located at the inner end of said inner tube and having a nozzle face, an ignition device leading from said body structure through said inner tube to said nozzle face, said head having a series of air ducts and a series of gas ducts terminating at said nozzle face in nozzle-mixing outlets with one series of said outlets alternating with the other series thereof around a common pitch circle centered on a common axis of said inner and outer tubes, means for passing gas and air separately through said body structure and respectively through said inner and outer tubes to said gas and air ducts, said outlets being directed at inclinations to the central axis of the head so that the gas jets diverge from said axis and the air jets converge thereon.

2. In a gas-fired tunnel burner of the nozzle-mixing type, the combination called for in claim 1 wherein the ducts of one series are inclined in the opposite direction to that of the ducts in the other series with each duct lying in a plane in which the central axis of the head lies.

3. In a gas-fired tunnel burner of the nozzle-mixing type, the combination called for in claim 1 including a tube of refractory material supported from and extending outwardly beyond said head so as to form a combustion tunnel in which the fiame is propagated and towards the inner wall of which the gas jets are directed.

4'. In a gas-fired tunnel burner of the nozzle-mixing type, the combination called for in claim 1 and wherein said head is carried on said inner tube, and including a support plate to which the outer end of said inner tube is rernovably secured and which is itself detachably securable to said body structure, whereby said plate, inner tube and head can be removed from said body structure as a unit.

5. In a gas-fired tunnel burner of the nozzle-mixing type, the combination called for in claim 1 and including a recuperator integral with the burner, said recuperator being formed by longitudinal metal fins projecting outwards from said outer tube to form, with a surrounding casing or wall in which the burner is inserted, ducts for the return flow of combustion products, and an ejector chamber in said body structure communicating with said ducts and with a flue outlet and having an air jet ejector located opposite to said outlet and fed by air from the interior of said body structure.

6. In a gas-fired tunnel burner of the nozzle-mixing type, the combination called for in claim 2 and wherein said ignition device passes axially through said head so as to leave space for a small quantity of gas to pass therethrough to the centre of said converging air jets.

References Cited UNITED STATES PATENTS 1,731,722 10/1929 Meier 158-99 2,571,336 10/1951 Buckholdt 158-7 2,668,592 2/1954 Piros et al. 158-99 3,044,551 7/1962 Pryor 158--99 3,163,202 12/1964 Schmidt et al. 1587.5

FREDERICK L. MATTESON, JR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.