US3512911A

US3512911A - Flare stack burner

Info

Publication number: US3512911A
Application number: US763846A
Authority: US
Inventors: Robert D Reed; John S Zink
Original assignee: John Zink Co
Current assignee: Zinklahoma Inc
Priority date: 1968-09-30
Filing date: 1968-09-30
Publication date: 1970-05-19
Anticipated expiration: 1987-05-19
Also published as: DE1946526B2; DE1946526A1; FR2019152A1; GB1218306A

Description

May 19, 1970 E ETAL FLARE STACK BURNER 2 Sheets-Sheet 1.

Filed Sept. 30, 19 68 //v l/ENTORS ROBERT D. REED JOH/V SMITH Zl/VA 24 BY r A ATTORNEY May 19, 1970 R. D. REED ET AL FLARE STACK BURNER 2 Sheets-Sheet 2 Filed Sept. 30, 1968 K M57. E 70 N N.H R M m N MAT pm Mr 0 wQ United States Patent 3,512,911 FLARE STACK BURNER Robert D. Reed and John S. Zink, Tulsa, Okla., assignors to John Zink Company, Tulsa, Okla, a corporation of Delaware Filed Sept. 30, 1968, Ser. No. 763,846 Int. Cl. F23b /00; F23c 9/00 U.S. Cl. 431-202 7 Claims ABSTRACT OF THE DISCLOSURE A burner assembly for the combustion of flared gases at the upper end of a stack wherein steam and air is mixed with the gas in the combustion zone and turbulence is developed promoting mixing of the steam and air with the gases to provide substantially smokeless burning.

The present invention pertains to a burner assembly for the combustion of gases at significant elevations above the surrounding terrain and the invention more specifically pertains to structural elements in association with a flare stack to deliver steam and air in adequate quantities plus energy to provide turbulence promoting rapid mixing of these components in the combustion zone adjacent the upper end of the stack to provide substantially smoke free burning of dump gases.

The prior art includes flare stack burners which provide for the combustion of waste or dump gases at the upper end thereof and steam has been used for promoting smokeless combustion. Such flare stack burners perform satisfactorily when the character of the dump gases is of one general type or when the velocity of the discharge is substantially uniform or when the diameter of the flare stack is of a small type. It has been found that when the diameter of the flare stack is increased the prior devices do not provide for the delivery of the smoke suppressant over the entire cross-sectional area of the discharge opening and the prior devices do not function to adequately mix the air and steam with the waste gases.

It is accordingly an object of the present invention to provide structure 'for delivering air and steam to the presence of the waste gases at the upper end of a flare stack so as to distribute the smoke suppressant and air throughout the waste gases and to provide structure for developing turbulence promoting mixture of the air and steam with the waste gases to provide for substantially smoke-free combustion.

Another object of the invention is to provide a flare stack structure with equipment providing for the delivery of air and steam into the combustion zone and to provide energy for developing turbulence therein promoting rapid mixing of the steam and air with the waste gases at the upper end of the stack so as to provide for substantially smokeless burning of various types of dump gases.

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

In the drawings:

FIG. 1 is a side elevational view of the upper end portion of a flare stack embodying the invention with portions shown in section.

FIG. 2 is a plan view of the upper end portion of the stack and taken on the line 2-2 of FIG. 1.

FIG. 3 is a sectional elevation view taken on the line 33 of FIG. 2.

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 2.

3,512,911 Patented May 19, 1970 FIG. 5 is a sectional view taken on the line 5-5 of FIG. 4.

FIG. 6 is a sectional view taken on the line 66 of of FIG. 2.

FIG. 7 is a sectional view taken on the line 77 of FIG. 6.

A flare stack is shown at 15 which is adapted to be erected in a substantially vertical position. The stack may be formed of tubular sections to have any desired height so that the upper end 16 is disposed at a significant elevation above the surrounding terrain. The upper end of the stack 15 includes an annular member 17 having a relatively large central opening 18 defined by the inner edge of a web 19. The combustion zone is adjacent the upper end of the stack and pilots (not shown) are employed to initiate combustion.

A vertical conduit portion 21 (FIG. 3) is arranged at the axis of the stack 15 and a lateral extending portion projects through the wall of the stack 15 and is equipped with a depending portion 23. Steam at pressure is supplied through a pipe 24 which escapes through an orifice in a nozzle 26 into the lower end of the conduit portion 23. The steam escaping through the nozzle 26 creates a low pressure condition within the lower end of the conduit portion 23 so that air is drawn into the conduit and mixes with the steam. The mixtur of air and steam moves upwardly in the conduit and escapes through a discharge device 28 which forces radial dispersion of the steam and air. The discharge device 28, as shown in FIG. 4, includes a top disc 29 which is supported on a base member 31 by a plurality of circum'ferentially spaced lugs 32. Open areas 33 are provided between adjacent lugs. The peripheral portions of the disc 29 and the base member 31 are inclined upwardly in proceeding radially outward as will be apparent from a consideration of FIG. 4. Such structure provides for a discharge of the mixture of steam and air as separate streams 30 which slant upwardly in proceeding radially from the axis of the conduit portion 21. The purpose of the discharge device 28 is to promote mixing of steam and air with the flared gases and this function is facilitated by the high velocity of the streams 30. The lugs 32 shield circumferentially spaced areas 35 wherein there is no radial movement of the steam and air mixture. The high pressure in these areas serves to relieve the low pressure zone 40 over the downstream end of the disc 29. If desired ports 25 may be provided which extend through the disc 29.

A plurality of circumferentially spaced and vertically disposed pipes 36 are disposed about the conduit portion 21 as shown in FIG. 3. A portion 37 of each pipe 36 extends outwardly through the wall of the stack 15 and the lower ends are open as depicted in FIG. 3. A manifold 38 surrounds the stack -15 and steam under pressure is supplied thereunto. A nozzle 39 is provided on the manifold 38 directly under the lower open end of each of the pipe portions 37. A jet of steam is delivered into the open lower end of each pipe portion 37 and air is aspirated into each which mixes with the steam. The steam and air mixture is delivered into the vertical portions of the pipes 36.

A cover member 41 is provided over the upper end of each pipe 36. The cover member 41 (FIG. 6) has a central opening 42 which has a diameter less than the internal diameter of the associated pipe 36. The cover members 41 are supported on the respective pipes 36 by a plurality of circumferentially spaced depending legs 43. Open areas 44 are thus provided between the legs 43 and the upper end of the associated pipe 36. A plurality of circumferentially spaced ports 46 are provided through the wall of the pipe 36 immediately below the cover member. There is a development of impact pressure as the steam and air mixture moves from the interior of the pipe 36 through the opening 42. Thus the pressure in the annular area. indicated at 47 is greater than the pressure in the central portion in the opening 42 to thereby provide for radial outward movement of steam and air in the area between the legs 43. The ports 46 also provide for a radial discharge of the steam and air mixture. The diameter of the opening 42 being smaller than the diameter of the interior of the pipe 36 provides a reduction in the flow area through the opening 42 to provide radial dispersion of the steam and air to thereby enlarge the area around each pipe 36 serving to suppress smoke.

An annular conduit 51 is provided above the manifold 38 adapted to receive steam under pressure. A plurality of vertically disposed nozzle 52 are mounted on the conduit 51 at circumferentially spaced locations about the stack which are in open communication therewith. The nozzles have outlet tubes 53 as shown in FIG. 1 so as to direct steam radially inward and substantially at right angles towards the axis of the stack 15. The nozzles 52 are arranged close to the periphery of the stack and deliver a maximum of turbulence and a minimum of air into the burning zone. A plurality of circumferentially spaced slanted nozzles 56 may be mounted on the conduit 51 and these are in communication therewith. Outlet tubes 57 are provided on the nozzles 56 and these tubes deliver steam jets radially inward towards the axis of the stack but these streams are inclined inwardly at an angle of about forty-five degrees with respect to a horizontal plane. The slanted steam jets deliver a minimum of turbulence to the combustion zone but induce a maximum quantity of air to move into the burning zone. The nozzles supplied with steam by the annular conduit 51 may all be disposed like the nozzles 52 or they may all be arranged like the nozzles 56. In the embodiment shown iln FIG. 1, a slanted nozzle 56 is mounted between each two circumferentially spaced vertical nozzles 52.

While the invention has been described with regard to particular structural arrangements it will be appreciated that changes'may be made in the elements as well as the over-all assembly. Such modifications and others may be made without departing from the spirit and scope of the invention as set forth in the appended claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a flare stack burner, a vertically disposed tubular member for guiding gas upwardly therein, said tubular member having a central opening at the top for the up- Ward escape of the gas, a plurality of pipes each having a vertically disposed portion circumferentially spaced within the tubular member adjacent the perimeter of said opening and terminating adjacent the top of said tubular member, a cover member over the upper end of each pipe having a central opening of smaller diameter than the associated pipes, each of said pipes having a plurality of circumferentially spaced ports below said cover member, means for guiding a mixture of air and steam into said pipes for vertical projection through the central opening in the respective cover members and for lateral projection through said ports, a conduit having a vertical portion adjacent the axis of said stack and terminating near the top thereof, a base member carried by the upper end of said conduit, a disc member supported above said bare member with open perimeteral areas between said base member and said disc member, and means for supplying mixture of steam and air into said conduit for projection radially between said disc member and said base member.

2. In a flare stack burner according to claim 1 wherein the disc member is supported by circumferentially spaced lugs which cause the steam and air mixture to be projected laterally as individual radial streams.

3. In a flare stack burner according to claim 1 wherein the disc member is provided with ports therethrough with the axes disposed in vertical directions.

4. In a flare stack burner according to claim 1 including an annular steam supply conduit surrounding the stack adjacent the upper end thereof, and nozzles supported by and in open communication with said conduit for directing steam in radially inward directions towards the axis of said tubular member.

5. Apparatus according to claim 4 wherein the nozzles are disposed to direct steam substantially at right angles to the axis of the tubular member.

6. In a flare stack according to claim 5 wherein the nozzles directed the steam radially inwardly toward the axis of the tubular member and upwardly with respect to a horizontal plane.

7. In a flare stack according to claim 1 including an annular steam supply conduit surrounding the stack, circumferentially spaced nozzles supported by and in open communication with said conduit, alternate of said nozzle directing the steam towards the axis of said stack substantially at right angles thereto, and the other nozzles directing the steam towards the axis of the stack and upwardly at an acute angle with respect to a horizontal plane.

References Cited UNITED STATES PATENTS 2,761,496 9/1956 Verner et a1 431-202 2,779,399 1/ 1957 Zink et a1. 431-202 3,273,627 9/1966 Zink et al. 431202 3,429,645 2/ 1969 Reed 43 1-202 EDWARD G. FAVORS, Primary Examiner U.S. Cl. X.R. 23 -277 a