US3202203A

US3202203A - Burner for gaseous fuels

Info

Publication number: US3202203A
Application number: US238151A
Authority: US
Inventors: Robert D Reed
Original assignee: John Zink Co
Current assignee: Zinklahoma Inc
Priority date: 1962-11-16
Filing date: 1962-11-16
Publication date: 1965-08-24
Anticipated expiration: 1982-08-24
Also published as: GB1030315A

Description

Aug. 24, 1965 R. D. REED 3,202,203

BURNER FOR GASEOUS FUELS Filed Nov. 16, 1962 2 Sheets-Sheet l INVENTOR ROBERT D. REED BY Q MLML,

ATTORNEY Aug. 24, 1965 R. D. REED 3,202,203

BURNER FOR GASEOUS FUELS Filed Nov. 16, 1962 2 Sheets-Sheet 2 o o o (L0- 36 ROBERT D. REED F/6.7 BY f M A TTORNEY United States Patent 3,202,203 BURNER FUR GASEOUS FUELS Robert 1). Reed, Tulsa, Glda, assignor to John Zinh Company, Tulsa, Uklzu, a corporation of Delaware Filed Nov. 16, 1962, Ser. No. 238,151 3 Claims. (Ql. l58116) The present invention relates to a fuel burner for gaseous fuel and more specifically pertains to a spider type fuel burner and the invention pertains to the shape of the downstream surfaces of the arms of the spider together with the disposition of the discharge ports and the lateral structure of the arms to provide a burner which is stable in operation when the air premixed with the gaseous fuel is as much as theoretical air and to pro vide structure which promotes cooling of the arms of the spider and provides for accelerated burning of the gaseous fuel without impairing stable operation.

A spider type burner head for gaseous fuel has been a useful device for industrial heating purposes. The air moving furnaceward over the burner head between the radially disposed arms together with the air mixed with the gaseous fuel provides the total air quantity for combustion of the fuel. The quantity of these lair volumes must exceed theoretical air. The rate of burning is substantially proportional to the percentage of air mixed with the fuel prior to release of the fuel mixture into the zone of combustion. The quantity of primary air is readily controlled so that it is not subject to any substanial variation in volume. air varies in accordance with the draft conditions in the vicinity of the combustion chamber and adjustable lair registers while helpful do not completely solve the problem. The pressure externally of the furnace is depressed or elevated by wind currents and changes in the pressure drop across the burner provide variations in the volume of the secondary air. A conventional spider type burner provides stable operation when the air mixed with the gaseous fuel prior to release by the burner head does not exceed thirty-five to fifty percent of theoretical air. Thus secondary air in volume is necessary to provide complete combustion of the fuel supplied to such burners. Variations in the volumeof secondary air makes operation of a conventional spider burner difficult.

It is an object of the present invention to provide a The quantity of secondary u spider type burner so shaped and constructed and with such a disposition of the discharge ports that stable operation is provided even when the gaseous fuel is mixed with as much as one hundred percent theoretical air which Will then be present in the combustion zone regardless of variations in pressure conditions in the vicinity of the furnace which may tend to alter the quantity of secondary air and to thereby provide a burner head wherein any changes in the volume of secondary air will only alter the volume of air in excess of theoretical.

Another object of the invention is to provide surfaces on the arms of the spider type burner which shield the exit ends of the discharge ports from direct unimpeded entry of secondary air and to provide structure on the burner head which serves to develop an enlarged eddy area downstream of each burner arm and to provide structure developing extensive diversion of the gaseous fuel mixture escaping through the discharge ports into the enlarged eddy area to develop adequate heat and maintain stable combustion even when air in excess of fifty percent of theoretical air is present in the gaseous fuel streams released int-o the combustion zone.

A further object of the invention is to provide flanges along the sides of each spider arm which increase the width of the hollow arms and provide shoulders which shield the exit ends of the discharge ports from direct and unimpeded entry of air including gusset webs in association with the flanges which serve to conduct heat from the flanges and the downstream portions of the spider arms to the upstream portions and assist in preventing overheating of the portions of the arms which are subjected to maximum heat.

Another object of the invention is to provide an elongated concave cavity which extends lengthwise along each side of a spider arm with the exit ends of the discharge ports so located within the cavities and with the discharge ports so oriented that there is impacting of the gaseous fuel streams in elongated areas along the sides of the arms from which secondary air is diverted to provide for diversion of the gaseous fuel into an eddy area which is developed throughout the downstream portion of each spider arm to thereby promote continuous rekindling of the fuel mixture.

A further object of the invention is to provide structure on the arms of the spider which promotes move ment of greater quantities of the cool incoming gaseous fuel mixture over and in intimate contact with the downstream faces of the arm to further prevent overheating of these portions of the burner head.

Other objects and features of the invention will be appreciated and become apparent as the present disclosure proceeds and upon consideration of the following detailed description taken in conjunction with the accompanying drawings wherein an embodiment of the invention is disclosed.

In the drawings:

FiG. 1 is a plan view of a burner head embodying the invention mounted in an opening in a furnace wall.

FIG. 2 is a sectional view taken on the line 22 of FIG. 1.

FIG. 3 is an enlarged transverse sectional view of one of the arms and taken on the line 3--3 of FIG. 1.

FIG. 4 is a side elevational view of one of the arms and taken approximately on the line 4-4 of FIG. 1.

FIG. 5 is an enlarged transverse sectional view taken on the line 55 of FIG. 1 and diagrammatically illustrating the development of the eddy area as a consequence of the movement of secondary air and the impingement of gaseous fuel streams.

FIG. 6 is a fragmentary plan view of one side portion of a spider arm diagrammatically illustrating the diversion of the gaseous fuel longitudinally to further promote stable operation.

FlG. 7 is a longitudinal sectional view of one of the spider arms illustrating a modification for developing the shape of the flame.

The spider type burner head may be formed of any suitable diameter. The number of arms of the spider may be altered in accordance with the diameter and the burner head shown in FIGS. 1 and 2 is representative and is provided with ten radially disposed hollow arms 11. The arms ll maybe formed integral with and radiate from a hub 12 into which gas mixed with air is supplied through a conduit 14. The burner head as hereinafter described provides stable combustion of fuel when the air mixed with the gaseous fuel constitutes as much as theoretical air to thereby provide for accelerated combus-tion of the gaseous fuel because the rate of burning is proportional to the percentage of air which is mixed with the fuel prior to the arrival of the gaseous f-uel in the combustion zone. Such a mixture of air and gas is suppliedinto the hub 12 and moves into the hollow arms 11 for release into a combustion chamber.

The burner head is desirably mounted .in a circular opening 16 provided in the wall 17 forming a part of the furnace or combustion chamber. The opening 16. provides a passage for secondary air to move into the combustion chamber between the hollow arms 11. The

volume of secondary air may be controlled by a disc shaped damper 18 which is mounted for adjusted positions in relation to the portal of the opening 16.

The hollow arms 11 are of identical construction and the free ends are closed by walls 21. The structure of the spider type burner head thus far described is of a known construction and novel stucture is provided throughout the downstream portion of each hollow arm which are equipped with external surfaces together with structure at the sides and discharge ports so located and oriented that all of these features function to maintain rekindling of the gaseous fuel having air mixed therein in amounts which constitute substantially theoretical air and structure which promotes cooling of the arms and cooling of the hub.

The downstream wall of each hollow arm has a ridge 23 extending throughout the length thereof as best shown in FIGS. 1 and 3. This longitudinal extending convex surface which is arched shaped when viewed in section has such a radius that space is provided laterally of the arcuate ridge 23 to provide

concave surfaces

24 and 26. These

concave surfaces

24 and 26 extend throughout the length of the arms 11. The radius about which each of these concave surfaces is generated is such that a substantially flat surface 27 is provided in an area downstream of the side wall 31 and a substantially flat surface is found downstream of the side wall 32. The

surfaces

27 and 28 extend throughout the length of the arms 11 and are in a plane substantially parallel to a plane which is at right angle to the axis of the burner head. The substantially flat surface 27 is extended laterally of the arm by a surface 33 on a flange 34 and the substantially fiat surface 28 is extended laterally of the arm by a surface 36 formed on a flange 37. The

flanges

34 and 37 extend substantially throughout the length of each hollow arm 11 but terminate short of the perimeter of the hub 12 with end edges 38 as shown in FIG. 1. The generally triangular shaped spaces between the end edges 33 and the hub allow the secondary air to flow unimpeded over these portions of the burner head.

A plurality of gusset webs 39 depend from the flange 34 at spaced interval along the length thereof. The webs 39 are desirably formed integral with the flange 34 and with the side wall 31 to provide good heat conducting characteristics through the gusset webs from the flange 34 to the side wall 31. Gusset webs 4 1 of similar construction are formed integral with the flange 37 and the side wall 32. The gusset webs 39 and 4.1 do not alter the path of movement of secondary air over the side portions of the hollow arms 11 but serve to conduct heat from the associated flange and the adjacent portions of the arm 11 to upstream portions of the associated hollow arm.

The arched ridge 23 provides an interior contour which extends throughout the length of each hollow arm 1.1 and receives the gaseous fuel mixture. A row of circular shaped discharge ports 42 are provided along one side of the arched portion of each arm as shown in FIGS. 1 and 5. A similar row of discharge ports 43 are formed along the other side of the ridge. The included angle between the axes of the

main discharge ports

42 and 43 is approximately one hundred twenty degrees with the axes of the ports of each row disposed at an angle of approximately sixty degrees with respect to a plane 44 which extends through the axis of the burner head and which represents a projection of the center line of each hollow arm 11.

Another row of discharge ports 46 of smaller diameter are provided on each hollow arm 11 with their exit end flush with the concave surface 24 and the ports 46 are located adjacent the inner surface of the side wall 31. Each discharge port 36 is in transverse alignment with one of the ports 43. The discharge ports 46 are of smaller diameter than the discharge ports 43. Another row of discharge ports 47 are provided along the other side of each arm 11 and the exit ends of the ports 47 are flush with the concave surface 26 and the ports 4'7 are arranged along the inner surface of the side wall 32. The axis of each discharge port 47 is in transverse alignment with the axis of a discharge port 42. Each discharge port 47 is of smaller area than a discharge port 42. The axis of the

discharge ports

46 and 47 may vary and converge towards the central plane 44 but are desirably parallel to the plane 44.

In operation and when gaseous fuel with air mixed therewith is in the neighborhood of theoretical is supplied into the hub 12 under pressure the gaseous fuel moves into all of the hollow arms 11. The gaseous fuel escaping through the discharge ports 47 engages the fuel jets moving from the discharge ports 42 and impact at a zone which is close to the exit ends of the

ports

42 and 47. The volume of fuel flowing through the larger ports 42 is deflected by the impingement. The energy of the smaller gas stream produces some flattening of fuel stream issuing through the discharge port 42. A similar condition is developed at the opposite side of each arm 11 and the smaller jets of gaseous fuel escaping through the ports 46 engage the larger fuel streams escaping through the discharge ports 4-3 close to the exit ends of the discharge ports.

The secondary air moves downstream over the hollow arms ill in directions approximating those represented by the arrows in FIG. 5. The secondary air flows over the length of the

gusset webs

39 and 41 and over the free edges of the flanges 3d and 37. The substantially flat surface 28 provides a shoulder shielding the exit ends of the

discharge ports

42 and 47 from the secondary air and the flange 37 with its flat downstream surface 36 provides a lateral extension of the shoulder provided by the surface 28. Similar structure at the other side of each hollow arm Ill and the flange 3d and its surface 33 provide a lateral extension of the shoulder 27 to divert the secondary air from the exit ends of the

discharge ports

43 and 46.

Such structure provides for a widening of the downstream portion of each hollow arm 11 so that an enlarged eddy area of the secondary air is developed throughout the downstream surface of each arm and throughout a zone indicated by phantom lines 48. The enlarged eddy area provides an environment of slow moving gaseous fuel to provide time for the fuel to partially burn and develop adequate heat for maintaining ignition of those portions of the fuel jets which are not diverted. The increase in the lateral dimensions of the arms and the shoulders avoids direct access of the secondary air to thereby avoid reduction of the flame temperature to promote stable burning even though the air mixed with the gaseous fuel approaches one hundred percent theoretical. The ports shielded by the shoulders on the arms 11 provide for pronounced diversion of the gaseous fuel mixture to the eddy areas to provide volumes of burning fuel in the eddy areas sufficient for the heat supply thereof to keep the flame stable even when one hundred percent of the theoretical air is mixed with the gaseous fuel. The fuel escaping from the discharge ports 47 impinges with the fuel escaping through the discharge ports 42 at a point or zone which is close to the exit ends of these ports which is shielded by the shoulder structure at the associated side of the arm. This arrangement provides for a diversion of the gaseous fuel mixture into the eddy area as represented diagrammatically at 51 and 52 in FIGS. 5 and 6. Similar diversion of the gaseous fuel mixture takes place adjacent the ports 43 and 4-6. This extensive diversion causes cool gases to move over the downstream surfaces of the arm to promote a reduction in the operating temperature of the arms.

The

shoulders

27 and 28 together with the lateral extensions of these shoulders as provided by the

surfaces

33 and 36 on the flanges shield the exit ends of vented from direct and unimpeded entry into the gaseous -fuel streams escaping through the discharge ports. The

secondary air moving over the

side walls

31 and 32 of each arm serve to cool the arm and the

gusset webs

39 and 41 serve to enlarge the surface area and act as fins for transferring heat to the secondary air. Heat is conducted by the gusset webs from the

flanges

34 and 37 to the upstream portions of the

side walls

31 and 32 where it is scrubbed by the secondary air.

The structural characteristics of the burner arms 11 permit air to be mixed with the gaseous fuel in quantities of as much as one hundred percent of theoretical. There is nevertheless suflicient diversion of the gaseous fuel in the eddy area downstream of each spider arm to provide suificient heat to maintain stable operation of the burner. Increased quantities of cool gasses diverted into the area along the downstream face of each arm also provides for movement of the cool gaseous fuel into the presence of the arms and to avoid the tendency of overheating of the structure of the spider arms.

The shape of the flame may be altered by providing additional discharge ports 56 in the spider arms near the free ends thereof as shown in FIG. 7. When the control ports 56 have their axes at right angles to the plane of all of the arms 11 the flame has a diameter substantially equal to the diameter of the burner head. The diameter of the flame may be enlarged by arranging the axes of the ports to diverge from the axis of the burner head.

While the invention has been described with reference to a spider type burner head having one set of arms it will be appreciated that the number of arms may be altered and the diameter of the burner head may be changed. The angles at which the discharge ports are formed may be varied and other changes may be made in the structure of the burner. These and other modifications may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A spider type burner head for gaseous fuel comprising, a hollow hub, a plurality of hollow arms carried by said hub extending generally radially from the perimeter of said hub, means supplying a mixture of gaseous fuel mixed with more than fifty percent theoretical air under pressure into said hub for movement into said arms, each arm having a ridge convex shaped in section extending lengthwise thereof forming the central downstream extremity of each arm, a longitudinally extending surface concave shaped in section at each side of said ridge, a longitudinally extending surface positioned outwardly of each concave surface forming a generally downstream facing surface adjacent each side of each arm, a flange projecting laterally from each side of each arm extending continuously along the length thereof with inner ends of the flanges spaced from the perimeter of said hub, each flange having a downstream facing surface enlarging the width of the associated downstream facing surface, each arm having main discharge ports spaced from each other along each side of said ridge with the axes of the main ports at each side of said ridge diverging from a longitudinal central plane of each arm which intersects the axis of said hub at an angle of approximately sixty degrees, each arm having discharge ports spaced from each other along each side of said ridge and positioned outwardly of the main discharge ports, each of said second discharge ports being of smaller area than each of said main discharge ports with the exit ends terminating flush with the respective concave surfaces, a projection of an axis of each smaller discharge port at one side of said ridge intersecting a projection of the axis of an associated main discharge port whereby the gaseous fuel mixture escaping through each of the smaller discharge ports impacts the gaseous fuel stream escaping through a main port inwardly of the free edge of the respective flange providing diversion of the gaseous fuel mixture along said concave surfaces to promote stable burning of the gaseous fuel mixture, means guiding air for movement downstream of the burner head over sides of said arms and over free edges of said flange developing an eddy area along downstream portions of each arm, gusset webs joining said flanges with upstream sides of the arms conducting heat to upstream portions of said arms, and said webs extending in the direiction of movement of said air.

2. A spider type burner head for gaseous fuel comprising, a hollow hub, a plurality of hollow arms carried by said hub extending generally radially from the perimeter of said hub, means supplying a gaseous fuel under pressure into said hub for movement into said arms, each arm having a ridge convex shaped in section extending lengthwise thereof forming the central downstream extremity of each arm, a longitudinally extending surface substantially concave shaped in section at each side of said ridge, a longitudinally extending surface positioned outwardly of each concave surface forming a generally downstream facing surface adjacent each side of each arm, a flange projecting laterally from each side of each arm extending continuously along the length thereof with inner ends of the flanges spaced from the perimeter of said hub, each flange having a downstream facing surface enlarging the width of the associated downstream facing surface, each arm having main dis charge ports spaced from each other along each side of said ridge with the axes of the main ports at each side of said ridge diverging from a longitudinal central plane of each arm which intersects the axis of said hub, each arm having discharge ports spaced from each other along each side of said ridge and positioned outwardly of the main discharge ports, each of said second discharge ports being of smaller area than each of said main discharge ports, a projection of an axis of each smaller discharge port at one side of said ridge intersecting a projection of the axis of an associated main discharge port whereby the gaseous fuel mixture escaping through each of the smaller discharge ports impacts the gaseous fuel stream escaping through a main port inwardly of the free edge of the respective flange diverting some of the gaseous fuel mixture along said concave surfaces to promote stable burning of the gaseous fuel mixture, and means guiding air for movement downstream of the burner head over sides of said arms and over free edges of said flanges developing an eddy area downstream of each arm.

3. A spider type burner head for gaseous fuel com prising, a hollow hub, a plurality of hollow arms carried by said hub extending generally radially therefrom, means supplying a gaseous fuel under pressure into said hub for movement into said arms, each arm having a ridge extending lengthwise thereof forming the central downstream extremity of each arm, a surface at each side of said ridge forming a longitudinally extending cavity along each side of each arm, a longitudinally extending surface positioned outwardly of each first surface forming a generally downstream facing surface longitudinally of each side of each arm, each arm having main discharge ports spaced from each other along each side of said ridge with the axes of the main ports diverging from a longitudinal central plane of each arm which intersects the axis of said hub, each arm having discharge ports spaced from each other along each side of said ridge and positioned outwardly of the main discharge ports, each of said second discharge ports being of smaller area than each of said main discharge ports, a projection of an axis of each smaller discharge port at one of side of said ridge intersecting a projection of the axis of an associated main discharge port Where by the gaseous fuel mixture escaping through each of the smaller discharge ports impacts the gaseous fuel stream escaping through a main port inwardly of the side of the associated arm providing diversion of the gaseous fuel mixture lengthwise Within the associated cavity promoting stable burning of the gaseous fuel mixture, and means guiding air for movement downstream of the burner head over sides of said arms 10 developing an eddy area downstream of each arm.

References Citeu by the Examiner Zinc 158-404 X Sterrick.

Leonard. Zinc 1581l6 X Zinc et al. 158113 Reed.

Williams 158-413 JAMES W. WESTHAVER, Primary Examiner.

Claims

3. A SPIDER TYPE BURNER HEAD FOR GASEOUS FUEL COMPRISING, A HOLLOW HUB, A PLURALITY OF HOLLOW ARMS CARRIED BY SAID HUB EXTENDING GENERALLY RADIALLY THEREFROM, MEANS SUPPLYING A GASEOUS FUEL UNDER PRESSURE INTO SAID HUB FOR MOVEMENT INTO SAID ARMS, EACH ARM HAVING A RIDGE EXTENDING LENGTHWISE THEREOF FORMING THE CENTRAL DOWNSTREAM EXTREMITY OF EACH ARM, A SURFACE AT EACH SIDE OF SAID RIDGE FORMING LONGITUDINALLY EXTENDING CAVITY ALONG EACH SIDE OF EACH ARM, A LONGITUDINALLY EXTENDING SURFACE POSITIONED OUTWARDLY OF EACH FIRST SURFACE FORMING A GENERALLY DOWNSTREAM FACING SURFACE LONGITUDINALLY OF EACH SIDE OF EACH ARM, EACH ARM HAVING MAIN DISCHARGE PORTS SPACED FROM EACH OTHER ALONG EACH SIDE OF SAID RIDGE WITH THE AXES OF THE MAIN PORTS DIVERGING FROM A LONGITUDINAL CENTRAL PLANE OF EACH ARM WHICH INTERSECTS THE AXIS OF SAID HUB, EACH ARM HAVING DISCHARGE PORTS SPACED FROM EACH OTHER ALONG EACH SIDE OF SAID RIDGE AND POSITIONED OUTWARDLY OF THE MAIN DISCHARGE PORTS, EACH OF SAID SECOND DISCHARGE PORTS BEING OF SMALLER AREA THAN EACH OF SAID MAIN DISCHARGE PORTS, A PROJECTION OF AN AXIS OF EACH SMIALLER DISCHARGE PORT AT ONE OF SIDE OF SAID RIDGE INTERSECTING A PROJECTION OF THE AXIS OF AN ASSOCIATED MAIN DISCHARGE PORT WHEREBY THE GASEOUS FUEL MIXTURE ESCAPING THROUGH EACH OF THE SMALLER DISCHARGE PORTS IMPACTS THE GASEOUS FUEL STREAM ESCAPING THROUGH A MAIN PORT INWARDLY OF THE SIDE OF THE ASSOCIATED ARM PROVIDING DIVERSION OF THE GASEOUS FUEL MIXTURE LENGTHWISE WITHIN THE ASSOCIATED CAVITY PROMOTING STABLE BURNING OF THE GASEOUS FUEL MIXTURE, AND MEANS GUIDING AIR FORO MOVEMENT DOWNSTREAM OF THE BURNER HEAD OVER SIDES OF SAID ARMS DEVELOPING AN EDDY AREA DOWNSTEAM OF EACH ARM.