US2235242A - Wide range air register - Google Patents

Description

March 18, 1941. R. c. VROOM WIDE RANGE AIR REGISTER Filed Jan. 30, 1939 March 18, 1941.

R. c. vRooM WIDE RANGE AIR REGISTER 2 shew-sneer 2 Filed Jan. 30, 1939 i lNvl-:N-TOR aaf/ Ewan BY l l I f .I'

ATTORNEY Patented Mar. 1S, 1941 parte STATES PATENT iTFlCE.

WIDE RANGE AIR REGISTER Application January 30, 1939, Serial No. 253,609.

16 Claims.

This invention relates to`air registers or the like of the type having inlet air passages through which air is supplied to the register, and more particularly to an air register for use in a burner for liquid, gaseous or pulverized fuels.

The invention is applicable, for example, to air registers of the general type shown in the patent to Peabody, No. 1,527,214, dated Feb. 24, 1925, having a housing provided with a set of peripheral air doors which are adapted to be actuated so as to provide controllable air passages therebetween for supplying air to the register tangentially and causing the air to whirl or rotate therein as it advances to the burner throat. The fuel supply or atomizing means may be vlocated at the axis or at the periphery of the burner throat.

In order to adapt this type of register to different fuel capacities the air doors may be adjusted to vary the opening therebetween or the doors may remain in xed adjustment and the air pressure may be varied. Both of these methods have certain disadvantages. For example, when the air doors are adjusted, the direction and velocity of the air are altered as well as the quantity admitted to the register. This alters the rotary motion of the air within the register 4and changes the characteristics of the burner. On the other hand; if the doors remain in fixed position and the air pressure is varied, the velocity of the air passing through the register and the velocity of the air at the burner throat are altered, with a consequent tendency for decreased turbulence and decreased rapidity of mixture of air and fuel at low capacities.

It is an object of the present invention to provide an air register having means for adjusting the quantity of air supplied to the burner throat without altering the characteristics of the air flow within the register.

Another object is to provide an air control for an air register of the type above indicated which is capable of varying the quantity of air supplied to the burner throat without changing the total quantity or velocity of air passing through the register.

Another object is to provide an air register control Which may be utilized to control the air supply to burners, fan inlet boxes or the like, without altering the internal structure or adjustment of the device.

Another object is to provide an air register control which automatically maintains a predetermined pressure drop through the register regardless of the operating capacity.

A further object is to provide an 'air register (Cl. 15S-1.5)

having means for withdrawing and returning a controlled portion of the air prior to passage through the burner throat.

Another object is to provide a system of the above type in which the velocity of the air through the air doors, through the register structure and in the fuel zone, will be maintained substantially constant at all capacities, whereby the eiciency of mixture of the combustion air and fuel will remain constant at al1 loads.

Various other objects and advantages Will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are believed to be characteristic of this invention .are pointed out more particularly in the claims appended hereto, the invention will be better understood by referring to the following description, taken in connection with the accompanying drawings, in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings:

Fig. 1 is a longitudinal sectional view through a register embodying the present invention;

Fig. 2 is a section taken along the line 2 2 of Fig. 1 showing the axial air return control plate;

Fig. 3 is a partial sectional view illustrating a diiferent embodiment of the invention;

Fig. 4 is a detail view showing a dilierent air control means;

Fig. 5 is a broken sectional view showing one means for maintaining acontrolled pressure differential between the plenum chamber andthe return chamber; and

Fig. 6 is a broken sectional View showing the invention applied to a furnace operating with natural draft.

Referring to the drawings more in detail, the invention is shown in Fig. 1 as applied to an air register structure forming apart of a burner which is disposed in the kfront wall I of aiurnace. The wall lil is formed of the usual refrac'tory material and is provided with an open ing Il in which is positioned a ring of refractory blocks l2 having. ared inner surfaces I3 forming the burner throat. A plate I4 may be secured over the front of the wall lil by any suitable means and may comprise the support for the air register structure. An inner ring l5, forms the discharge opening of the air register. It may be attached to the plate t4 .by suitable means, such as ybolts I6.

The .Plate I 4 supports a wind box or plenum chamber 2!) comprising top plate l1, bottom plate 22, front plate i8 and rear plate l 9, which are senections.

- gaged by pins 46 mounted in a ring 41.

cured by a suitable means, such as angle irons or the like, located at the various joints. The rear plate I9 is spaced from the plate I4 to form an air return chamber 2 I.

The air register is shown as comprising a front plate 25 attached to the front plate I8 by bolts 26 and having a hub 21 in which the fuel supply barrel 28 is positioned. A set screw 29 may be provided for holding the barrel 28 in any position of adjustment. The barrel 28 may carry a tip 30 and a diffuser 3|, which may be positioned within the burner throat, and may be provided with a coupling member 33 carrying the fuel con- The barrel 28 may be adapted to supply liquid, gaseous or pulverized fuel, and may comprise, for example, a liquid fuel atomizer of the wide range type such as: described in Peabody Patent 1,628,424, dated` May 10, 1927, in which the operating capacity or load is adjusted by controlling the fuel pressure.

The -air register is shown as provided with a set of peripherally arranged air doors 38 which are mounted on spacers 39, carried on bolts 48 extending between the front plate 25 and a rear plate 4| and forming a support for the rear plate. The rear plate 4| may be provided with suitable sealing means, such as a ring 42 of soft material adapted to engage the rear plate I9 of the Wind box so as to effect an air-tight joint.

The front plate I8 may have an opening I8a of a size to permit the entire air register to be removed therethrough When the supporting bolts 26 are removed. The front plate I8 may constitute the front baiiie of the wind box and may be supported independently of the plate I4 if desired.

The air doors 38 may be provided with inwardly extending cams 44 having slots 45 en- The ring 41 may be seated in a recess in the front plate 25 and may be actuated by a pinion 48 carried on a shaft 49 journalled in a boss 50 in the front plate 25 and actuated by an operating handle 5|. Rotation of the shaft 49 by means of the operating handle 5| causes rotational movement of the ring 41, thereby shifting the cams 44 and varying the annular position of the air doors 38. It is to be understood, of course, that the air doors may be actuated by other control mechanism and that they may be operated either in unison or independently as may be desired. Furthermore, the doors may be arranged in the form of a frustum of a cone, as shown in Patent 1,527,214, above mentioned.

The rear plate 4| terminates in an inner flange which is spaced from the inner ring 5 to provide an annular air passage 56 therebetween. The flange 55, however, is preferably in substantialalig'nment with the inner ring I5 so that, in effect, a continuous air passage is provided from theregister to the burner throat.

Suitable means may be provided for adjusting the opening of the air passage 56. In the embodiment shown, this means comprises a sliding ring 51 which is mounted Within the flange 55 and is actuated by a rod 58 extending through the front plate 25 and provided with a handle 59. The ring 51 thus slides axially of the burner to variably adjust the opening of the air passage 56.

In certain instances it may be desirable to remove the return air from around the atomizer barrel near the axis of the air register or at the front of the register. This is accomplished in the present construction by a housing 65 ypositioned around the hub 21 and attached to the front plate 25 by bolts 66. The housing 65 forms an annular air passage 64 around the hub 21, the front plate 25 being provided With a plurality of apertures 61 to permit passage of air from the air register into said passage. Adjusting means comprising an adjusting plate 68 having va similar set of apertures 69 may be journalled about the hub 21 and may be rotatably adjusted by a handle 10 attached thereto4 and extending through a slot 1| in the front plate. A rotary adjustment of the plate 68 accordingly varies the effective size of the apertures 61 through which the air passes from the air register into the passage 64.

The specic form of control means for controlling the air supplied to the passage 64 may, of course, be varied.

Combustion air may be supplied to the plenum chamber 28 by means of a fan 15 having a discharge duct 16 communicating with said chamber 20 and having an intake duct 11 communieating withthe return chamber 2|, an intake duct 18 communicatingwith the atmosphere and a duct 19 communicating With the housing 65. Dampers 80, 8| and 82 are positioned in the respective ducts to adjust the air flow therethrough. A damper 83 may be provided in the discharge duct 16 to control the air supply to the chamber 20. In certain instances either the chamber 2| or the passage 64, with their corresponding ducts, may be omitted.

In the operation of the system thus far described, air `is supplied under pressure by the fan 15 to the chamber 20 and passes `between the air doors 38 into the interior of the air register wherein it is caused to rotate, due to the angular position of said doors. It then passes to the burner throat wherein it is suitably mixed with the atomized fuel. of the air is withdrawn through the return chamber 2| and returned to the fan by the duct 11. The pressure in the plenum chamber 20 may be controlled by the operation of the fan 15 and A controlled proportion A by the, damper 83. The pressure in the return chamber 2| may be controlled by the damper 80 or by the position of the ring 51. Likewise, the quantity of air Withdrawn axiallyof the register through the vpassage 64 may be controlled by the damper 82 or the plate 6 8. Y

At maximum load the dampers 89 and 82 may .1

be fully closed so that no air is withdrawn through the return chamber 2| or the passage 64 and the full capacity of the air register is supplied to the burner throat. The velocity and direction of the air may be controlled by the setting of the air doors and by the pressure m-aintained in the plenum. chamber 20. When the fuel supply is reduced by suitable adjustment of the atomizer or of the fuel pressure, as more fully set forth in Patent 1,628,424 above mentioned, the air supply may be correspondingly reduced by adjusting the dampers 80 or 82,V the ring 51 or the plate 68, so as to Withdraw a portion of the air from either thereturn chamber 2| or the passage 64 or from both as may be desired. The air supply to the burner throat is thus reduced Without reducing the velocity in the air register, whereby the eiciency of air flow and the rapidity of mixing the air and fuel is maintained at various loads.

If, for example, the pressure in the return chamber 2| is greatly reduced, corresponding to a condition in which a large proportion of the air is returned and a small quantity is supplied. to the burner throat, the pressure drop across the air doors andV through the air register increases and the velocity of the air within' the air register and the total quantity of air pumped; may be correspondingly increased. In order to avoid this, the pressure of the air vsupplied to the register may be varied to correspond to the changes in return pressure. This may be accomplished by manual adjustment of the damper 83 or it may be accomplished automatically.

One type of automatic control is lshown in Fig. 1 `as comprising a pressure line 90 communicating at 9| with the chamber 2| and vhavinga branch 92 communicating with Vthe lduct 19, suitable valves t3 and 94 being provided to shut ofi one of these lines if the corresponding vduct is not being utilized for air return purposes. The pressure linel 99 is shown as connected to actuate a diaphragm valve 95, controlling uid under pressure received by a Vline 96 from a source not shown and connected by a line 91, having a vent |89, to actuate a pressure motor, such as a bellows 96 which is connected by a linkage 99 to control the damper 83.

The valve 95 and the pressure motor 98 are so adjusted that the pressure in the plenum chamber 28, as controlled by the ldamper 83, is varied in the same sense as the pressure in the return chamber 2|,or in the return duct 19, as the case may be, so as to maintain a predetermined pressure differential across the air doors or through the register, regardless of the quantity of air withdrawn and returned to the intake of the fan.

By returning the air from the return chamber 2| after it has been discharged from the register, the velocity of air through the doors and the rotational effect within the register are maintained constant. In case it is only required to maintain the velocity through the air doors constant, the air may be withdrawn axially through Vthe duct 19. The relative quantities so taken may, of course, be controlled by the `dampers BIJ vand 82 or by the control ring 51 and the adjusting'plate 68. Ordinarily, air will be taken from only one of these locations, although, in certain instan-ces, the two ducts 11 and 19 may be used at the same time. Obviously, either the chamber 2l or the passage 64 may be omitted Vif not requiredin `any particular installation. l

In a further embodiment of the invention shown in Fig. 3, the return air is taken from a point past the plane of fuel supply so that the quantity and velocity of air initially contacting the fuel remains unaltered as the 'operating capacity is varied. In this embodiment, the construction is generally similar to that of Fig. 1, with the exceptionof the back plate 41a. This plate 4 la is provided with a curved conical inner surface extending vpastthe plane of the diffuser 3|. The blocks I2 are cut back, as at |02, and the inner ring ||l3 is curved inwardly to 'provide an air passage vIIlli corresponding'to the air passage 56 of Fig. 1, but displaced toward the interior of the furnace.

The register thus forms a converging axial/air discharge opening at the burner throat to increase the air velocity prior to impinging on the cone of fuel. The diffuser provides 'a central adjustable coaxial restriction for 'further controlling the zone of maximum velocity. Thereturn passage communicates with the register peripherallyat a point beyond the minimum iow area so that variations in return flow do not'alter the condition of air flow through the register ornt the point of impinging on the fuel. This con-'- struction accordingly provides a uniform mixn ture' of fuel and air and maintains uniform combusti'on conditions regardless of the load.

In Fig. 4 a dilferent type 'of control is provided for the air passage 56. In this embodiment the ring I5 corresponding to the ring I5 of Fig. 1 is formed as part of the rear plate 4| and is provided With av flange |I6 which bears against the plate- Iil. The ring ||5 is provided with a plurality of apertures ||1 through which the air passes to the return chamber 2|. For adjusting the effective size of these apertures, an inner Aadjusting ring I I6 is provided having corresponding apertures ||9 and journalled for rotary movement Within the ring H5. This adjusting ring I I8 may be provided with a rack |26 which may be actuated by a pinion |2| carried on a shaft |22 which extends through the front plate, not shown. Actuation of the shaft |22 causes the ring ||8 to rotate so as to vary the overlap of the apertures IIS and ||1. The shaft |22 may be journalled in a plate |23 which may also secure the ring IIS against axial movement. Obviously, the construction may be varied, making the ring ||8 axially adjustable, as shown, for example, in connection with the ring 51 of Fig. 1.

In Fig.y 5 is shown an embodiment of the invention using a pressure relief valveto control the pressure in the plenum chamber 26 in accordance with variations in pressure in the return chamber 2.1 `or vice versa. In this embodiment a pressure relief valve |25 is provided in a duct |26 interconnecting the discharge duct 16 andthe return duct 11, the arrangement being otherwise similar to that shown in Fig. 1, with the exception of the bellows 98 and the actuating mechanism` therefor, which may be omitted. The control, in this embodiment, may be effected by means of the damper 6| in the duct 82 leading to the atmosphere. Sufficient air may be supplied through the duct B2 to compensate for the air which is discharged into the furnace through the burner throat. A constant pressure diierential is automatically maintained between the plenum chamber 29 and the return chamber 2| by means of relief valve |25. The quantity of air supplied to the burner throat may accord-` ingly be regulated by suitable control of the damper 8|.

The 'invention may also be applied to a furnace operating with natural or induced draft or at a subatmospheric pressure. Such an embodiment is illustrated in Fig. 6 in which a stack |30 is connected to the furnace through a ue |3I. The return duct 11 may be connected toa duct |32 passing beneath the noo-r of the furnace and connected to the flue |6| or directly to the stack |30. The quantity of air passing through the duct |32 may be controlled by a damper |33. A damper |34 may be'provided in the flue |3| for controlling the furnace draft. The arrangement is such that the return air from the return chamber 2| is passed directly to the stack. The duct |32 may be arranged so that the return air is utilized for cooling the furnace floor or the return air may be used for other purposes before being passed to the stack. Additional air for cooling the furnace floor may be supplied to the duct |32 through a duct |36 leading to the atmosphere and controlled by a damper |31. Such additional air supply may beL used, for example, when the burner is operated at high capacity which involves 'the use of a minimum amount 'of-return air.

-Itfisvt'o Pbe understood, 'of course, that the air f control may be applied to air registers for various purposes, such, for example as fan inlet boxes or the like. The term air register, as used herein, is to be construed accordingly. Furthermore, the invention is not limited to the particular construction of air register herein disclosed, but may be applied to various standard types of air registers for use with liquid, gaseous or pulverized fuel which may be supplied peripherally as well as axially, as shown, for example, in U. S. Patents No. 1,671,494, to C. R. Stewart, dated May 29, 1928; No. 1,790,395 to S. T. Warner, dated Jan. 27, 1931; and No. 1,865,983 to S. T. Warner, dated July 5, 1932. Furthermore, thegas may be supplied axially instead. o-f through the peripheral chamber or various combinations of the liquid, gaseous and pulverized fuels may be employed.

Although a speciiic embodiment of the invention has been shown for purposes of illustration, it is to be understood that the invention is capable of various uses and that changes and modifications may be made therein as will be readily apparent to a person skilled in the art. Certain specific terms have been used herein merely for convenience of description and not as a limitation on the scope of the invention.

-Theinvention is to be limited only in accordance with the following claims.

What is claimed is: I

1. In combination, an air register having discharge opening, air admission means including peripheral air admission` ports to supply air to said register, and means to withdraw a portion of the air from said register after passage through said ports and prior to passage through said discharge opening, so as to control the quantity of air discharged therethrough.

2. In combination, an air register having a discharge opening, air admission means including peripheral air admission ports to supply air to said register, means comprising an air return passage communicating with said register at a point beyond said ports in the direction of air flow to withdraw a portion of the air therefrom after passage through said ports and prior to passage through said discharge opening, and means controlling the pressure in said air return passage to thereby Vary the quantity of air withdrawn therethrough.

3. In combination, an air register having a discharge opening, air admission means to supply air to said register, means comprising air return passages communicating with said register at different zones to withdraw a portion of the air therefrom, and means controlling the pressure in each of said air return passages to thereby vary the quantity of air withdrawn therethrough, for thereby controlling the zone from which said return air is withdrawn from said register.

4. In combination, an air register having a discharge opening, air admission means including peripheral air admission ports to supply air to said register, means comprising an air return passage communicating with said register at a vpoint beyond said ports in the direction of air ister at a controlled pressure, means comprising an air return passage communicating with said register to withdraw a portion of the air therefrom, means controllingthe pressure in said returnpassage to thereby vary the quantity of air withdrawn therethrough and means varying the pressure of air supplied to said register in a sense to maintain a predetermined pressure drop across saidregister.

6. In combination, an air register having a discharge opening, pressure means including a fan to supply air under ypressure to said register, means withdrawing a portion of the air from said register prior to passage through said discharge opening andmeans returning said portion to said fan for recirculation.

7. In combination, an air register having a set of peripheral air doors adapted to admit a controlled quantity of air in a direction to form a rotating mass of air therein and provided with a. discharge opening arranged to discharge the air axially of saidregister, means supplying air to said register at a controlled pressure, and means to control the quantity of air discharged through said discharge opening, said control means comprising an air return passage arranged to withdraw-azportion of the whirling mass of air from said register, and means controlling the air pressure-in said return passage for varying the quantity of air thus withdrawn.

8. In combination, an air register having a set of peripheral air doors adapted to admit a controlled quantity of air in a direction to form a rotating mass of air therein and provided with a discharge opening arranged to discharge the air axially of said register, means supplying air to said register at ra controlled pressure, and means to control the quantity of air delivered through said discharge opening, said control means comprising an air return passage arranged to withdraw a portion of the whirling mass of air from Within said register, means controlling the air pressure in said return passage for varying the quantity of air thus withdrawn, and means varying the supply pressure in the same sense, so as to maintain a predetermined pressure drop across the` air doors, whereby the air velocity through said doors and the speed of rotation-of the mass of air in said housing are unaffected by changes in operating capacity.

9. The invention set forth in claim 7 in which the returnv passage communicates with the interior of the register-at a point near the axis of the rotating mass of air.

10. The invention set forth in claim 7 in whichv the return passage communicates with the interior of the register at a lpoint remote from the axis of the rotating mass of air.

v11. The invention set forth inclaim 7 in which the return passage communicates withY the periphery of the Vrotating mass of air so as to withdraw the portion centrifugally,

12. The invention set forth in claim 8 in which a control member is provided to vary the supply pressure and said member is actuated in response to changes in pressure in said return passage.

13. The invention set forth in claim 7 in which a differential pressure control system is provided to vary theV supply pressureV in accordance with changes in pressure in the return passage, so as to maintain a predetermined pressure drop across said register. v

14. An air supply system for a burner having a throat and means to produce a cone of fuel therein fory combustion, said system comprising an air register, means supplying air thereto at a controlled pressure, peripherally arranged air doors in said register to admit a controlled quantity of said air thereto and toimpart a whirling motion to said air, said register having an axial air discharge opening communicatingwith said burner throat to supply air for combustion purposes, and means to control the air supply to said burner in accordance with changes in operating capacity While maintaining substantially constant air flow conditions Within the register, said control means comprising a return passage communicating with the register at said discharge opening to Withdraw a portion of the air prior to passage through said throat, and means controlling the quantity of air Withdrawn through said return passage.

15. The invention set forth in claim 14 in which the return passage communicates with the burner throat beyond the point of the fuel supply whereby the rapidity of mixture of air and fuel is not aiected by changes in operating capacity.

16. An air supply system for a burner having a throat and means to produce a cone of fuel therein for combustion, said system comprising an air register, means supplying air thereto at a controlled pressure, peripherally arranged air doors in said register to admit a controlled quantity of said air thereto and to impart a whirling motion to said air, said register having a converging axial air discharge opening to increase the air velocity prior to impinging on said cone of fuel, and a central adjustable coaxial restriction for further controlling the zone of maximum velocity, said axial discharge opening communicating With said throat so as to supply air for combustion purposes and means to vary the air supply to said burner While maintaining substantially constant air flow conditions Within said register, comprising a return passage communicating with said register at the periphery thereof to Withdraw a portion of the air from said axial discharge opening beyond the point of minimum flow area.

ROBERT C. VROOM.

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