US3765824A

US3765824A - Apparatus for determining air flow to a gas burner

Info

Publication number: US3765824A
Application number: US00278839A
Authority: US
Inventors: N Trozzi
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1972-08-02
Filing date: 1972-08-02
Publication date: 1973-10-16
Anticipated expiration: 1990-10-16
Also published as: ES417780A1; JPS4967223A; CA976078A; JPS542231U

Abstract

An apparatus for determining air flow to one or more burners of a furnace or the like wherein an enclosure is provided which surrounds the burners and receives air for supply to the burners. A register assembly is provided in the enclosure and cooperates with the burners to direct a predetermined portion of the air to a combustion zone adjacent each of the burners. A static pressure zone is created for the latter portion of air to enable its static pressure to be measured and the air flow to be determined.

Description

United States Patent Trozzi Oct. 16, 1973 APPARATUS FOR DETERMINING AIR FLOW TO A GAS BURNER [75] Inventor: Norman K. Trozzi, West Caldwell,

[73] Assignee: Foster Wheeler Corporation,

Livingston, NJ.

[22] Filed: Aug. 2, 1972 [21] Appl. No.: 278,839

[52] US. Cl. 431/188, 431/12 [51] Int. Cl. F23n 3/00 [58] Field of Search 431/188, 12, 174

[56] References Cited I UNITED STATES PATENTS 3,486,834 12/1969 Frey et al 431/188 X 3,700,376 10/1972 Niedenberg et al. 431/188 X Primary Examiner--Edward G. Favors Attorney-John Maier, III et a].

[57] ABSTRACT An apparatus for determining air flow to one or more burners of a furnace or the like wherein an enclosure is provided which'surrounds the burners and receives air for supply to the burners. A register assembly is provided in the enclosure and cooperates with the burners to direct a predetermined portion of the air to a combustion zone adjacent each of the burners. A static pressure zone is created for the latter portion of air to enable its static pressure to be measured and the air flow to be determined.

8 Claims, 4 Drawing Figures .PATENIEDucI 15 ms SHEET 105 2 APPARATUS FOR DETERMINING AIR FLOW TO A GAS BURNER BACKGROUND OF THE INVENTION This invention relates to an apparatus for determining air flow to one or more burners in connection with a furnace, such as the furnace section of a vapor generator, or the like.

In the use of furnaces associated with vapor generators or the like, primary air is normally introduced with the fuel into the combustion zones defined by the burners associated with the furnace, while secondary air is introduced from a different location into the combustion zones to promote the combustion. The secondary air is normally introduced through a windbox associated with the burners and is directed toward the combustion zones by a register assembly. However, in relatively large installations incorporating a plurality of such burners, several problems are involved in the use of this secondary air. For example, since each burner has a different location relative to the secondary air source, and since the registers associated with each burner are usually adjusted to different positions, the actual air flow to each burner can vary. Also, the mass flow effect of the incoming air into the windbox causes uneven distriubtion of air to each burner.

As a result, the air-fuel ratio at each combustion zone is somewhat unpredictable which makes it impossible to control the combustion and the resultnat flame conditions with any precision.

Also, the measurement and control of secondary air flow to the burner has become increasingly important in view of recent emphasis on reducing atmospheric contamination by minimizing the presence of nitrogen oxides in the air. This is largely due to the fact that it has been discovered that the reduction of nitrogen oxides in the effluent gases produced in such furnaces is considerably aided by reducing the theoretical combustion air that is introduced to the burner, since the absence of sufficient oxygen in the hottest portion of the flame causes the available oxygen to combinewith carbon rather than with nitrogen and thus substantially reduce the formation of nitrogen oxides.

In the latter context, it is apparent that a precise measurement and control of the secondary air to the burner is extremely advantageous.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an apparatus for determining air flow to the burner or burners in a furnace or the like in order to insure predictable combustion and flame conditions as well as to enable the theoretical amount of air to be controlled in accordance with particular requirements.

Toward the fulfillment of these and other objects, the apparatus of the present invention comprises an enclosure surrounding the burner or burners, means for introducing air at a predetermined velocity to said enclosure, register means disposed in said enclosure and cooperating with each burner for directing a predetermined portion of said air to a combustion zone adjacent each burner, means for creating a static pressure zone for said 13 predetermined portion of air, means for measuring the air pressure in said static pressure zone, and means for measuring the air pressure in said enclosure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view showing the apparatus of the present invention in connection with a burner assembly disposed in a furnace section of a vapor generator;

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is an enlarged cross-sectional view taken along the line 3-3 of FIG. 2; and

FIG. 4 is a reduced perspective view depicting the apparatus of the present invention mounted over a burner assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The assembly of the present invention will be described in connection with a vapor generator for the purposes of example, with the reference numeral 10 referring to a heat absorption fin tube wall which forms the furnace section of the generator.

A casing wall 12 cooperates with the fin tube wall 10 to define an interior portion 14, it being understood that the latter is bounded by upper and lower walls, as viewed in FIG. 1, to define an enclosure, or windbox, which receives air'at a predetermined velocity from a source such as a fan (not shown) with the direction of air flow into the interior portion 14 being shown in general by the arrows in FIG. 1.

An annular insulation collar 16 extends in an opening formed in the fin tube wall 10 with its inner surface defining a combustion zone 18, which extends into the furnace.

A burner assembly, shown in general by the reference numeral 20, extends through the wall 12 with one end of the assembly extending flush with one end of the collar 16, and with the assembly being supported in a coaxial relationship to the collar by means of a register shown in general by the reference numeral 24.

The register 24 comprises a pair of

annular mounting plates

26 and 28 disposed in a spaced relationship, with the plate 26 extending over and being secured tothe burner assembly 20. The plate 28 is secured to the collar 16 with their respective openings registering, as shown. I

A plurality of vanes 30 are journaled between the two mounting plates 26 and 28'and extend around the entire outer periphery defined by the

plates

26 and 28. The position of the vanes 30 are adjustable by means of a plurality of cranks 32 operatively connected to each vane in order to direct the air in a particular path towards the combustion zone 18.

A hood, shown in general by the reference numeral 40, extends over the register 24 and is formed by a pair of spaced

annular plates

42 and 44 respectively connected to the

mounting plates

26 and 28 by means of a plurality of mounting brackets 46. A circular perforated plate 48 is connected to the ends of the

plates

42 and 44 to complete the hood.

As better shown in FIG. 3, a pipe 50 extends across the hood 40 and is secured to the

plates

42 and 44. The pipe 50 is perforated in its central portion and supports a drum 52, the outer wall of which is also perforated. The right end of the pipe 50 is closed by means of a cap member'54 as viewed in FIG. 3, while the left end is conected to a manometer tube 56 as shown in FIG. 1.

The purpose of the perforated plate 48, perforated drum 52, and the corresponding perforated portion of the pipe 50 is to reduce the effect of the velocity pressures on the air entering the hood 40 and thus create an essentially static pressure zone within the pipe 50 to enable the static air pressure to be measured by means of the manometer associated with the tube 56.

As shown in FIG. 4, the air hood 40 has four pipes 50 spaced therearound at equally spaced intervals so that an average value of the air pressures transmitted by their corresponding tubes 56 may be obtained to use in determining the air flow.

An additional manometer tube 60 extends through the casing wall 12 for transmitting the static pressure existing in the interior portion 14 to the exterior.

The burner assembly is of a conventional design incorporating six gas guns 62, an oil gun 64, and anigniter 66 which operate in a conventional manner to create a continuous flame at the combustion zone 18.

In operation, secondary air is directed into the combustion zone 18 through the air hood 40 and the register 24, as shown by the arrows, while tertiary air and fuel isintrodu'ced to the combustion zone through the burner assembly 20. It should be understood that the burner assembly 20 does not utilize what is known in the art as primary air, since normally this would be associated with solid fuel burning equipment as opposed to liquid or gaseous fuels.

The

tubes

56 and 60 are connected in a manner so that the average static air pressure in the hood 40 and the static air pressure in the interior portion 14 will enable air flow to the register 24 to be determined. The effect of register position on air flow to the combustion zone can be determined by the pressure differential across the hood.

Since a conventional installation of thistype will employ several of the burner assemblies 20 along with their associated components, it can be appreciated that the air flow may be easily determined at each burner assembly by simply measuring the static air pressure via the

tubes

56 and 60. Of course, in the event it is determined that an improper airfuel mixture is occurring at any particlar burner, the, fuel and/or air supply may be adjusted accordingly by conventional means.

Of course, variations of the specific construction and arrangement of the apparatus disclosed above can be made by those skilled in the art without departing from the invention as defined in the appended claims.

l claim:

1. Apparatus for determining air flow to one or more burners of a furnace or the like, said apparatus comprising an-enclosure surrounding said burner, means for introducing air at a predetermined velocity to said enclosure, register means disposed in said enclosure and cooperating with said burner for directing a predetermined portion of said air to a combustion zone adjacent each of said burners, means for creating a static pressure zone for said predetermined portion of air, means for measuring the air pressure in said static pressure zone, and means for measuring the air pressure in said enclosure.

2. The apparatus of claim 1 wherein said furnace forms a portion of a vapor generator, a plurality of said burners being mounted adjacent port openings pro vided along a heat absorption wall of said generator.

3. The apparatus of claim 1 wherein said means for creating a static pressure zone comprises a perforated plate mounted relative to said register means in a spaced relation relative to the inlet portion of said register means, and a perforated tubular member mounted between said perforated plate and said inlet.

4. The apparatus of claim 3 wherein said perforated plate forms a portion of a hood surrounding said register means; said tubular member extending across said hood in the path of air flow from said perforated plate to said inlet.

5. The apparatus of claim 3 wherein said means for measuringthe air pressure in said static pressure zone is connected to said tubular member.

6. The apparatus of claim 1 wherein said register means is in the form of an annular housing surrounding each of said burners and having adjustable openings in the outer periphery thereof to direct said predetermined portion of air in a generally radial direction relative to said burner.

7. The apparatus of claim 6 further comprising an annular hood extending over said register means, the outer wall of said hood bei'ng perforated to permit said predetermined portion of air to pass therethrough into the inlet of said register means.

8. The apparatus of claim 7 wherein said means for measuring the air pressure in said static pressure zone comprises a perforated tubular member mounted relative to said hood and extending across said hood between said perforated plate and said inlet to receive a portion of said predetermined portion of air.

Claims

1. Apparatus for determining air flow to one or more burners of a furnace or the like, said apparatus comprising an enclosure surrounding said burner, means for introducing air at a predetermined velocity to said enclosure, register means disposed in said enclosure and cooperating with said burner for directing a predetermined portion of said air to a combustion zone adjacent each of said burners, means for creating a static pressure zone for said predetermined portion of air, means for measuring the air pressure in said static pressure zone, and means for measuring the air pressure in said enclosure.

2. The apparatus of claim 1 wherein said furnace forms a portion of a vapor generator, a plurality of said burners being mounted adjacent port openings provided along a heat absorption wall of said generator.

4. The apparatus of claim 3 wherein said perforated plate forms a portion of a hood surrounding said register means, said tubular member extending across said hood in the path of air flow from said perforated plate to said inlet.

5. The apparatus of claim 3 wherein said means for measuring the air pressure in said static pressure zone is connected to said tubular member.

7. The apparatus of claim 6 further comprising an annular hood extending over said register means, the outer wall of said hood being perforated to permit said predetermined portion of air to pass therethrough into the inlet of said register means.