US2911034A - Burner air flow control means - Google Patents

Description

Nov. 3, 1959 E. F. D. WEBB 2,911,034

BURNER AIR FLOW CONTROL MEANS Filed Nov. 16. 1955 2 Sheets-Sheet l FIG. 5

Nov.'3, 1959 E. F. n. WEBB BURNER AIR FLow CONTROL MEANS 2 SheetsfSheet 2 Filed Nov. 16, 1955 United States Pater-it BURNER AIR FLOW coN'InoL-'MnANS Edward F. D. Webb, Sandy Point,Y` Hayling Island, England Application November 16, 195s, seriai No. 547,243

4 claims. (C1. 15s- 76) The invention relates to means for modulating the flow of fluid through a conduit and particularly to means for controlling the supply of air or gas to an oil or like burner.

It is known Ithat in order to obtain complete combustion of the fuel in burners which are adapted forburning liquid fue1,`.gases and pulverised fuel, it is necessary to obtain intimate admixture of the fuel and air supplies, and to this endthe .air is admitted to the burner at positions in front of the actual combustion zone, through slots, or past'vanes or shaped blades, so as to impart high velocity Ito the air and to create turbulence in the cornbustion zone. Such slots, vanes or blades are usually disposed so as to direct the air at an angle to the axis of thefburner, being generally positioned radially around the axis of the burner kto impart av rotary or swirling motion to the air in contact with the fuel stream.

Such' means promote eicient combustion with a con- 'stant ratio of fuel and air in the correct proportions, but whereas the rate of flow of fuel can be controlled by 'simple means to alter the rate of firing of the burner, the rate of flow of air cannot be simply controlled without reducing theturbulence whichfis essential for goodfcom'- bustion. Normal means of controlling the rate ofair ow by 'a damper orvariation of -fan output controls the quantityof air but leaves the area of the air slots unchanged with consequentchange-in velocity of the air.

It is among the objects ofthe invention to provide means whereby the quantity of air 'admitted to the cornbustion space in front of a burner can be varied without appreciably varying the velocity of the air, therebyy maintaining violent turbulence at all rates of firing.

Itis a further object of the inventionjto render possible a wider turn-down ratio that is to say, ratio of maximum to minimum rate of firing at which the burner vis stable, and efficient, than has hitherto been possible in known oil-burning practice. t

According to the invention, means for controlling the air in a burner fory oil, gas or pulverised solid fuel, comprises a radially `disposed series of vanes made of a flexible 'material and mounted around a burner tube so as to be adapted to be twisted, bent or otherwise moved in such manner -as to guide the flow of fluid through -the duct,I the angle or surface of deflection of the vanes being variable by means operable from a position remote from the vanes, and advantageously through linkage operating alongthe axis of iiow of the fluid controlled. A

The vanes may be made of thin sheet metal of high temper, or of other resilient-material having both the leading and trailing edges stiffened in any suitable manner. The vanes are equally spaced in radial relation in a cylindrical conduit and formed with a general taper from the outer periphery of the conduit inwardly.

According to the invention furthermore, inthe application of the invention to oil burners with primary and secondary airflow, the means for controlling the iiow of primaryv air may be linked to the means for controlling the secondary 'air in such manner as continuously to retain a predetermined rrelation between them, thus the '2,911,034 Patented Nov. 3, 1959 rice y 0 a slidablesleeve provided 'with Va corresponding series of slots and so provided at one end to be connected to one or more hydraulically or pneumatically operated pistons, a spider secured at the other end of the slidable sleeve supporting the leading edges of a series of vanes, an outer sleeve on which is mounted a series of radial arms and an outer cylindrical housing, through which the secondary air flows, mounted on said radial arms and supporting the `trailing edge'o'r'part thereof of the series of vanes.

Thus it -will be understood that the quantity of' air passing between the vanes and also the angle ofits discharge arecontrolled by movement ofthe leading ends or parts of the vanes relatively'to the trailing ends or parts. i i

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which;

Figure 1 is a longitudinal section showing the control means for an oil or like burner according to the invention;

Figure 2 is a corresponding end elevation;

Figure 3 is an enlarged elevation of one vane;

Figure 4 isa diagrammatic layout of the'movement of one vane; and l Figure 5 is a part sectional view of a modified construction.

In carrying the invention into effect according to the 1 construction illustrated in the drawings, Ythe burner may comprise a sleeve 1 surrounding a burner tube 2 having a collar or annular flange 3i,r serving as an abutment for a purpose hereinafter described, and a gripping handle 4 for effecting insertion of the tube. The sleeve 1 is provided near the forward end wtih a circumferential'series of slots Sfor the introduction of primary air, and is formed at the 'outlet with an inwardly directed annular flange 6 so as to direct the primary air forwardly and inwardly onto the fuel issuing from thenozzle of the burner tube 2.

Surrounding the sleeve 1 is adapted to slide over the sleeve 1 along the axis of the burner tube 2, and is provided witha circumferential series of 4slots 8 at a lengthwise position in the sleeve correspondingV to the position of the slots 5 in theA sleeve 1.

Mounted on the forward end of `the slidable sleeve 7 is a spider '9 which is formed with a series of radial arms 1t) of channel or U-section into which the leading edge of each of a series of vanes 1l is securedas by pins or the like. l

The rear end of the slidable sleeve 7` is provided with a plate 1.2 to which are connected the rear ends of the piston rods 13 having at Ithe forward `ends pistons 14 operating within hydraulically or pneumatically operated cylinders lThe cylinders 15 are mounted on an end plate 16 which is secured in spaced relation to a backplate 17, which in turn-is secured to an outer sleeve 1S surrounding the rear end of the slidable sleeve1'7, which is formed to a reduced cross-section to present an annular shoulder 17A against which the forward end of the sleeve 18 bears in the fully open position ofthe vanes 11. Three or more radial arms 19 are secured to the -outer sleeve 1S and serve toV f. of secondary air lto the burner.

is a slidable sleeve 7, which- The trailing edges of the vanes 11 are secured to re inforcing pins 21 which are mounted as by universal joints 22 on the forward end of-the housing 20.

The housing 20, though normally stationary, is mounted .withrsliding fit within a cup-shaped casing 23, which is secured as by welding or the like to the front face 24 of the furnace, and is provided with laterally disposed air inlets 25, through Whch'the secondary airenters to pass into the housing 20.

The backplate 17 is held in contact vwith the base of the cup-shaped casing 23 by suitable locking means 26, to enable withdrawalof the complete burner into the casing 23, when not in use. VIn effecting this movement the housing covers up the air inlets 2S, and cuts off the air supplypwhich ensures that the burner is rendered inoperative. The withdrawal of the burner maybe effected by hand, hydraulically or pneumatically.

Mounted on the rear end of the sleeve 1 is a fuel control valve 27, through which oil from the main supply pipe 28 flows to the burner tube 2, through the oil pipe 29. The control valve 27 is provided with a control lever 30 which is effective to lock the burner tube 2 in position against lengthwise movement by vengagement with the collarV or ilange 3when fthe oil is flowing, and to only release the burner tube 2 -for withdrawal whennecessary, when the supply of oil is cut o.

In the operation of the burner, air is passed under pressure through the inlets 25 into the housing 20 and out past the vanes 11. Simultaneously, air from the housing 20 passes through the corresponding inlet slots 5, 8 into the annulus between the sleeve 1 and the burner tube ,2 and out around the nozzle of the burner tube 2.

Control of the secondary air is eected bymovement to bend thervanes 11 from the fully open position, where they lie substantially parallel to the longitudinal axis of the burner, to the fully closed position where they are substantially at right angles to this axis.

For this purpose the leading edge of the vanes y11 which is secured along its whole length to a radial arm 10 of the spider 9 is moved in the direction of the arrow-A (Figlure 4) towards the trailing edge, with the result 'that the general curve of the vane (as viewed along the upper edge) is altered from that indicatedby B in Figure 4 to thatH indicated by C shown in the same figure, andthe secondary air thus directed on to the issuing jet of oil and air at an angle a (corresponding to the curve C) In a modied construction, as illustrated in Figure 5, a iixed series of radially disposed vanes 11a may be provided, immediately adjacent the inner sleeve 1, and the series of radially disposed adjustable vanes 11 around the iixed vanes 11a.

In this embodiment, the ratio of the total area of both the adjustable and the lixed series of vanes to the area of the fixed series o f vanes will be approximately the turndown ratio'of' the burner.

This construction ensures that vigorous turbulence is maintianed adjacent the burner tube under low load operating conditions.

As illustrated, the xed series of radially disposed vanes 11a are mounted in any convenient manner around the sleeve 1, and a series of radial arms 33 are mounted on the forward end of the slidable sleeve 7, to support a ring 34 which overlaps the rear ends of the iixed vanes 11a. The spider 9 with arms 10 and the vanes 11 are mounted on the ring 34 in the manner hereinbefore described.

The slots 5, 8 former respectively in .the sleeves 1, 7 are provided in such manner that when the vanes 11 are in the fully closed position a space is left to allow sufficient primary air to pass through the slotsinto the inner sleeve 1 to ensure the. necessary predetermined relation between the primary air and the secondary air passing through the fixed vanes.

I claim:

1. Means for supplying fuel and modulating theflow of air to a burner comprising a housing forming an air passage, a tube located centrally of said housing through j which fuel is fed to a combustion chamber, aplurality of flexible, air-directing vanes spaced .around the forward end of the housing, mounted thereon and extending radially inwardly towards the tube to impart. a rotary motion to the air passing throughthe endof the .housing f past said'vanes, means for Variably flexing said vanes by movement of one edge of each vane axially of the tube `whereby the amount of air fed and its rotary motion are varied anda series of xed vanes mounted adjacent tothe tube and towards the inner end of the flexible vanes, whereby a turbulent ow of air may be maintained, near the outlet of the tube while the main body of .airis variinstead of at an angle corresponding tothe curve B, p

thus varying the area of discharge of the secondary air and the quantity of air admitted to the mixture of oil and primary air. l

Control of the primary air is effected by the longitudinal movement of the slots 8 over the slots 5 to vary `the size of the opening through which the air passes.

To adjust the primary and secondary air ows the slidable sleeve 7 is moved forwards and backwards along the axis'of the burner over the sleeve 1. This movement is effected by the pistons 14 operated through pipe lines 31 Afrom 'a suitable source of power supply.

' Thus it 'will be understood that the linking together of the control means for both the primary and secondary air Hows ensures a continuous predetermined ratio between them, which is essential for effective operation. Y Furthermore, means may be provided Ato pre-set the ratio between the primary and secondary air flows. This pre-setting may be effected by turning a handle 32 which yis secured to the rear projecting end of the sleeve 1 in such manner as to effect a rotational movement of the sleeve 1 relatively to the sleeve 7, and thus to vary the size ofthe opening, through which the air passes, radially.

It will be understood that the controlmeans in the fully closed position allows suicient air to pass through to keep the burner burning, thus providing against the possibility of the coking-up of the nozzle of the burner tube, should it be left for relatively long periods projecting into the hot furnace.

able.

2. Means for Vmodulating the flow of f luid through a conduit, including a cylindrical housing at least part of ywhich is mounted for axial movement Within the said conduit, a series of juxtaposed and flexible vanes radially mounted transversely of said cylindrical housing, a movable support forthe leading edges of said vanes, said movable support being in theA formr of an axially .slidable sleeve extending into said housing, a fixed support in the form of a stiffener for the trailing edges of said vanes, said stiifeners being mounted on said housing radial arms for supporting said housing, an outer sleeve on which said arms are mounted, said outer sleeve extending coaxially with and closely adjacent to part of said movable support, the portion of said movable support contained Within said outer sleeve being of reduced cross-section, the portion of larger cross-'section of said movable support abutting the said outer sleeve to limit movement of the movable support, and means for moving the said movable support axially to Hex said vanes to open and close said vanes.

3. Means for modulating the flow of a stream of uid, comprising a conduit through which the stream of fluid passes, a series of juxtaposed and flexible vanes radially mounted transversely of said conduit, said vane being adapted to be brought Ainto overlapping relation to close said conduit, an axially slidable sleeve extending into said conduit and forming a movable support for the leading edges of said vanes, a iixed support in the form of a stifener for the trailing edges ofsaid vanes, said stiifeners being mounted on said conduit, and means for moving said axially slidable sleeve to ex said vanes to open and close said vanes.

4. Means for modulating the flow of fluid through a conduit as set forth in claim 2 having a stationary hollow sleeve mounted within the slidable sleeve forming the movable support for the leading edges of the vanes, said stationary sleeve forming a primary passage for the fluid and corresponding openings in said stationary and slidable sleeves for the passage of luid to said hollow stationary sleeve, said openings being variable upon movement of the slidable sleeve whereby movement of the slidable sleeve varies the passage of fluid by the vanes and through the hollow stationary sleeve in a Xed ratio.

1,639,056 Peabody Aug. 16, 1927 6 Irish Apr. 10, 1928 Sallee Aug. 22, 1933 Steinman Aug. 10, 1937 Stratz Feb.v 15, 1938 Ru Apr. 2l, 1942 Nuyl July 18, 1950 Fritz No'V. 1l, 1952 Stillman Feb. 16, 1954 FOREIGN PATENTS Australia June 11, 1928 Germany Oct. 6, 1940 Italy July 19, 1951

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