US3273627A

US3273627A - Plaee stack burner assembly

Info

Publication number: US3273627A
Authority: US
Publication date: 1966-09-20
Anticipated expiration: 1983-09-20

Description

p 1966 J. s. ZlNK ETAL FLARE STACK BURNER ASSEMBLY Filed March 16, 1965 ll IIIIIIHI KTD Y mwmfi f TZMR M mmoakm wmwm M OHR V: B 2 a I F United States Patent 3,273,627 FLARE STACK BURNER ASSEMBLY John Smith Zink, Hershel Goodnight, and Robert D. Reed, Tulsa, Okla, assignors to John Zink Company, Tulsa, Okla, a corporation of Delaware Filed Mar. 16, 1965, Ser. No. 440,216 7 Claims. (Cl. 158-99) The present invention relates to apparatus for the combustion of gases which contain hydrocarbons and other inflammable materials which are often handled or developed in the process industries and to provide for the combustion of such gases high in the atmosphere and such equipment is often referred to as flare stack burners.

A flare stack burner must be continuously in an operable condition to burner large volumes of gaseous materials without smoke. In the past steam has been employed which functions satisfactorily for promoting complete combustion of the gaseous materials and the suppression of smoke. Steam in quantities necessary for carrying out complete combustion of the dump gases at the upper end of a flare stack involves costs which vary between eight and twenty-five dollars per hour of operation of the flare stack. Thus while the injection of steam into the combustion zone of a flare stack burner provides a desired result the costs of the required steam is burdensome and has led to the inject-ion of water into the burning gases. The sprayed water drop-lets are converted to steam which combines with carbon to provide carbon monoxide .and hydrogen both of which burn without smoke. The injection of Water into the burning gases thus serves to suppress smoke and involves costs which are materially less than those required for the injection of steam in the quantities sufficient to provide smokeless combustion of dump gases.

An essential requirement of a flare stack burner is that there must be no interruption of combustion of the dump gases and the apparatus must be continuously in an operative condition because the dumping or release of gases represents an emergency which is not predictable. Stable operation of the flare stack burner while the gases are released for upward movement in the stack is a necessary feature. The use of water for promoting smokeless combustion :at the upper end of a flare stack burner has not been entirely satisfactory for the reason that critical control of the volume of the water is required. If the quantity of water sprayed into the combustion zone is too great the resulting cooling action serves to interrupt operation of the burner.

An object of the invention is to provide for a partition structure at the upper end of a flare stack for separating a first portion of the gaseous material in a path separate from a second portion of the dump gases and to provide for the injection of the Water droplets into the first portion of the gaseous material while the second portion devoid of water burns stably and develops suflicient heat to vaporize the water droplets injected in the first portion and serves to heat the Water to super-heated steam whereby the carbon-water reactions may occur downstream of the stable burning gaseous material to thereby promote stable operation of the flare stack and the suppression of smoke Without means for controlling the quantity of the water in relation to the volume of gas being burned.

A more specific object of the invention is to provide a plurality of sleeves within the upper end portion of a flare stack through which portions of the gases move and to provide means for spraying water into those portions of the dump gases moving through the sleeves while other portions of the gases moving through the flare stack outside the sleeves :are shielded from the water spray and thus burn stably to maintain ignition at the upper end of the flare stack.

A still further object of the invention is to provide means for supplying water droplets in gases undergoing combustion at the upper end of a flare stack and means maintaining the flare stack burner operable in areas when the ambient temperatures fall below the freezing temperatures of water so that such apparatus will be operable for the release and combustion of dump gases during periods when temperatures fall below thirty-two degrees Fahrenheit.

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 following detailed description taken in conjunction with the annexed drawing wherein an embodiment of the invention is disclosed.

In the drawing:

FIG. 1 is a side elevational view partly in section illustrating a flare stack burner assembly embodying the invention.

FIG. 2 is a sectional elevational view on a larger scale and illustrating the upper end portion of the burner assembly.

FIG. 3 is a plan view of the burner assembly.

FIG. 4 is a transverse sectional view on a larger scale and taken on the line 44 of FIG. 1.

The stack may be formed of sections of tubular elements forming a tube disposed in a generally vertical position and the stack may be of conventional construction for guiding the gas for upward movement therein as shown at 10. The upper end of the tube 10 is disposed at a higher level than neighborhood buildings or the like. The gaseous materials which are to be disposed of by burning are rel-eased into the lower end of the stack and combustion takes place at the upper end and at the desired height above the surrounding terrain. The stack is maintained in an erect position in any suitable manner.

A burner tip 11 is carried by the upper end of the tube 10 and is provided with a relatively large central opening 12 as best shown in FIG. 3. The opening 12 is defined by the inner edge of a generally horizontally disposed flange 14 which forms a portion of the burner tip. A frusto-conical wall 16 extends downwardly from the periphery of the horizontal flange 14. A further horizontal flange 17 rests on and maybe attached to the upper end of the tube 10. A plurality of circumferen-tially spaced discharge openings 21 are provided in the conical wall 16. Similarly spaced discharge openings 22 are provided in the horizontal flange 17. The axes of the

openings

21 and 22 converge in such a manner that the gaseous material escaping through each pair of openings impinge near the exit ends of the discharge openings. A suitable p-ilot 26 is provided adjacent the upper end of the flare stack as shown in FIG. 1 for igniting the gaseous material escaping through the

discharge openings

21 and 22. Ignition of the gaseous material in the vicinity of the pilot 26 provides for combustion of the gas escaping through the

discharge openings

21 and 22 throughout the circumference of the burner tip. Stable burning is maintained by the impinging jets of gas escaping through

openings

21 and 22.

A feature of the apparatus includes partition means mounted in the vicinity of the combustion zone at the upper end of the tube 10-. The partition means in the embodiment illustrated takes the form of a plurality of sleeves 28 disposed in upright positions within the tube .10 and extending through the opening 12 in the burner tip. The sleeves are open and unobstructed at their lower and upper ends so that a portion of the gases released for upward movement through the stack passes through each of the sleeves 28. The sleeves may be of cylindrical formation as shown in FIG. 3 and arranged with an outer row of sleeves concentrically about a central sleeve. The

outer row of sleeves may be secured to the horizontal flange 14 in any suitable manner such as by welding and the peripheries of adjacent sleeves may be secured to each other by welding. The sleeves 28 may have any desired length but are desirably constructed and arranged to have approximately one-third of each sleeve projecting upwardly beyond the burner tip 11 whereby approximately two-thirds of each sleeve depends below the burner tip within the tube 10. Such a partition structure provides for some of the gaseous materials moving upwardly in the stack to move through the respective sleeves 28. The partition means provides generally triangularly shaped spaces 29 between the inner edge of the horizontal flange 14 and the exterior of the sleeves 28 through which other portions of the gas may escape from the stack without passing through any of the sleeves 28. Other generally triangularly shaped spaces 31 are provided between the exterior of the central sleeve 28 and the exterior of the outer row of sleeves 28 through which portions of the gaseous material may escape from the stack without passing through any of the sleeves 28.

The apparatus for the combustion of gaseous materials includes means for spraying water as small droplets into those portions of the gas moving through the sleeves 28. It is for this purpose that a spray nozzle 32 is mounted within each sleeve 28 below the free upper end thereof. Any suitable arrangement may be provided for supporting the nozzles 32 and supplying water thereto. In the embodiment illustrated each nozzle 32 is supported by a pipe 33 attached thereto and which extends along the axis of the associated sleeve and is connected at its lower end to a water supply conduit 34 by a suitable conduit fitting. The conduit 34 extends through the wall of the stack and downwardly to a ground level. -In order to avoid freezing of the water supplied into the conduit 34 it may extend below the surface of the ground. Water is supplied into the conduit 34 under suflicient pressure to pro- 'vide a pressure drop across the nozzles 32 of at least forty pounds to produce a spray of small water droplets. The flow of water may be controlled by a valve 37. The conduit 34 may be protected by an insulation covering 38 and suitable insulation may be provided as indicated at 36 to reduce the rate of heat loss from the water supply line when it is located above grade adjacent ground level.

In operation and when gas is released for upward movement within the stack 10 some of the gaseous materials move exteriorly of the sleeves 28 and escapes through the

openings

21 and 22 and is ignited by the pilot 26. The burner tip 11 serves to ignite and burn the gaseous material escaping through the generally triangularly shaped areas 29 which serve to deliver some of the gas into close proximity to the

small discharge openings

21 and 22. Combustion is thus established and maintained by the burning of the gaseous material which moves outside the sleeves 28. Those portions of the gaseous materials moving through the generally triangularly shaped spaces 31 contributes to stable burning of the gases.

The opening of the valve 37 admits water under pressure into the conduit 34 and a fine water spray is developed within each sleeve 28. Each nozzle 32 provides a conical spray pattern as represented by dotted lines in FIG. 2. The combustion of the gas which escapes from the stack 10 exteriorly of the sleeves 28 develops sufficient heat to vaporize the water discharged by the nozzles 32 and to super-heat the vaporized water droplets to provide steam at a temperature in excess of sixteen hundred and fifty degrees Fahrenheit and thereby promote the carbonwater reactions at a rate rapid enough for the suppression of smoke. The partition means which takes the form of the sleeves 28 provides apparatus wherein the water injection in the vicinity of the combustion zone may vary over a wide range Without developing cooling of the combustion zone to a temperature which interferes with stable burning of the gas exteriorly of the sleeves.

A further feature of the apparatus pertains to means providing for maintaining such apparatus operable in areas where the ambient temperature drops below the freezing temperature of water. Heat is supplied to the interior of the conduit 34 and such heat may be provided by exhaust steam from a turbine, pump or the like in the plant from which the dump gases are released. Such exhaust steam is at a low pressure and while devoid of ability to provide useful work retains heat. The exhaust steam may be re leased into a pipe 41 through a valve 42. The pipe 41 is of small diameter and extends into the conduit 34 as shown in FIG. 1. The steam delivered into the pipe 41 serves to supply heat to the water within the conduit 34 and avoid freezing in areas where low amibent temperatures develop. A check valve 43 is provided at the upper end of the pipe 41 to prevent water at pressures exceeding those of the steam to enter the pipe 41. The primary purpose of the steam is to prevent freezing but the steam is released by the check valve 43 and added to the water for discharge through the nozzles 32 for smoke suppression purposes. A trap 44 may be provided for drainage of condensate from the pipe 41.

While the invention has been described with reference to specific structural features and with regard to an arrangement partitioning portions of the interior of the upper end of a flare stack it will be appreciated that changes may be made in the components as well as the overall organization. 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 we claim and desire to secure by Letters Patent is:

1. In a flare stack burner, an elongated vertically disposed tube for guiding a combustible gas for upward movement therein, a burner tip at the upper end of said tube having a central opening for the escape of said gas, partition means within said central opening through which a portion of gas may escape, means for discharging water droplets into the gas within said partition means, and means providing for ignition and combustion of that portion of the gas escaping from the stack exteriorly of said partition means and which is shielded from the water droplets.

2. In a flare stack burner, a vertically disposed tube for guiding combustible gas for upward movement therein and for combustion adjacent the upper end thereof, said tube having a central opening for the escape of the gas, a plurality of vertically disposed sleeves each having an unobstructed lower and upper end mounted within said central opening through which portions of the gas move from the stack, a nozzle within each sleeve, means'for delivering water under pressure to all of said nozzles to spray small droplets of water into the gas within the respective sleeves, said sleeves providing open spaces within said central opening exteriorly of the sleeves through which other portions of the gas may escape from the stack, and means initiating combustion of the gas escaping from the stack exteriorly of said sleeves.

3. In a flare stack burner according to claim 2 wherein the sleeves extend above the upper end of said tube.

4. In a flare stack burner, a vertically disposed tube for guiding combustible gas for upward movement therein for burning adjacent the upper end thereof, said tube having a central opening therein for the escape of the gas, a plurality of vertically disposed substantially cylindrical shaped sleeves each having an open upper and open lower end mounted within said central opening through Which portions of the gas move upwardly for escape from the tube, means for spraying water into the gas within the respective sleeves, said sleeves providing open spaces within the central openings exteriorly of the sleeves through which other portions of the gas free of water may escape from the tube, and means for initiating burning of the gas escaping from the ube exteriorly of the sleeves to develop heat converting the sprayed water into steam promoting substantially complete c mbustion of all of the gas.

5. In a flare stack burner according to claim 4 wherein the sleeves are arranged as an outer row about a central sleeve and all of the sleeves depend into the upper end of said tube.

6. In a flare stack burner, an elongated vertically dis posed tube for guiding a combustible gas for upward movement therein, a burner tip at the upper end of said tube having a central opening therethrough for escape of said gas, means for discharging water droplets into the gas adjacent said burner tip, means shielding said Water droplets from other portions of the gas escaping through said central opening, said burner tip having circumferentially spaced discharge perimeter of said tube for escape shielded from the water droplets, and means for igniting the gas escaping through said discharge openings.

7. In a flare stack burner, a vertically disposed tube for guiding combustible gas upwardly therein for combustion adjacent the upper end thereof, said tube having a central opening therein for the escape of the gas, a plurality of vertically disposed sleeves each having an open upper and an open lower end mounted within said of some of the gas central opening through which portions of the gas may escape from the tube, a nozzle within each sleeve, conduit means extending upwardly from a region near the of the gas may escape from the tube, means for initiating ignition and combustion of the gas escaping from the tube exteriorly of said sleeves, and means for heating said conduit means to prevent freezing of the water JAMES W. WESTHAVER, Primary Examiner.

Claims

1. IN A FLARE STACK BURNER, AN ELONGATED VERTICALLY DISPOSED TUBE FOR GUIDING A COMBUSTIBLE GAS FOR UPWARD MOVEMENT THEREIN, A BURNER TIP AT THE UPPER END OF SAID TUBE HAVING A CENTRAL OPENING FOR THE ESCAPE OF SAID GAS, PARTITION MEANS WITHIN SAID CENTRAL OPENING THROUGH WHICH A PORTION OF GAS MAY ESCAPE, MEANS FOR DISCHARGING WATER DROPLETS INTO THE GAS WITHIN SAID PARTITION MEANS, AND MEANS FOR PROVIDING FOR IGNITION AND COMBUSTION OF THAT PORTION OF THE GAS ESCAPING FROM THE STACK EXTERIORLY OF SAID PARTITION MEANS AND WHICH IS SHIELDED FROM THE WATER DROPLETS.