Pilotless flare ignitor

Abstract

A pilotless flare ignitor which is capable of igniting waste gas issuing continually or sporatically from a flare stack and may include an ignitor housing having an open end which extends into the flare stack. At least two pairs of electrodes are mounted in the ignitor housing, and the electrodes of each electrode pair are positioned to define a spark gap for producing a spark in the ignitor housing. A timer controls the duration of the spark and repeatedly and continually alternates the spark among the multiple electrode pairs. As the gas continually or intermittently and sporadically flows upwardly through the flare stack and into the ignitor housing, the spark, alternating between the electrodes of the multiple electrode pairs, is continually present in the ignitor housing to ignite the waste gas in the ignitor housing and flare stack.

Description

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to devices for igniting combustible waste gases and more particularly, to a pilotless flare ignitor which utilizes a timed spark that alternates among multiple electrode pairs for igniting waste gas issuing from a flare stack. The pilotless flare ignitor may include an ignitor housing having an open end which extends through an opening provided in the flare stack. At least two pairs of electrodes are mounted in the ignitor housing, which electrodes of each electrode pair define a spark gap in which a timed spark is intermittently generated. The spark repeatedly and continually alternates among the multiple electrode pairs such that the spark is continually present in the ignitor housing. Accordingly, as waste gas either continually or intermittently and sporadically flows through the flare stack, all the waste gas is ignited and unignited waste gas is incapable of escaping from the flare stack.

[0003] Natural gas or methane is often found with deposits of petroleum. When the gas occurs in quantities which are too small for economical transportation to a point of use, the gas is considered waste gas and disposed of in the most convenient manner. For example, in oil drilling operations, natural gas frequently becomes mixed with the packing mud in the drill hole. The mud is passed through a mud-gas separator and the major portion of the mud re-circulated to the drill hole, while the gas is expelled through a vertical flare pipe. Whereas in earlier times the gas was simply vented into the atmosphere, current safety regulations generally require the waste gas, which typically contains entrained liquid hydrocarbons, to be burned or flared in order to prevent fire and explosion hazards.

[0004] Various arrangements have been devised for the ignition of combustible waste gases vented through vertical flare stacks Originally, methods of igniting the waste gas included shooting flaming arrows, tracer bullets or signal-type flares through the gas emanating from the flare pipe. However, these practices were unreliable at best and often proved dangerous to humans or livestock in the area of the stack. Another method of igniting the gas included burning an open container of liquid fuel, such as diesel fuel, near the flare pipe outlet. However, the burning diesel fuel was often extinguished by wind or rain, and re-ignition of the fuel in the presence of accumulating gas was extremely hazardous. Still another method included igniting the gas by an electric spark using an automobile spark coil, electric fence charger or other type of transformer, but since the spark plugs in these applications were placed directly in the stream of the burning gas, they were quickly fouled by oil and carbon build-up beyond further use. Additionally, the transformers were often damaged, either by the radiant heat of the gas flame or by the flame itself, as it was blown back toward the transformer by the wind.

[0005] Conventional waste gas flare ignitors typically utilize a pilot light or spark-generating electrode which is temporarily placed in the stream of the flowing gas to ignite the gas, and then retracted from the burning gas to prevent damage to the pilot light or electrode. Typical of these flare ignitors is the “Waste Gas Flare Ignitor” detailed in U.S. Pat. No. 4,431,402, dated Feb. 14, 1984, to Louis F. Hamilton. The flare ignitor is characterized by a movable pilot structure which burns a stored fuel for a selected period of time in order to ignite waste gas issuing from a horizontal flare pipe. The ignitor includes a heat shield, behind which the pilot structure is withdrawn after ignition of the gas, for protection from the heat of the burning gas. Another flare ignitor is the STACKMATCH (trademark) “Hot Rod”, manufactured by the Stackmatch Flare Ignition Corporation of Plano, Tex. The flare ignitor is characterized by a pilot gas conduit or pipe which is hingedly and vertically mounted on the flare stack and terminated by a series of pilot openings located between a pair of circular plates provided on the upper end of the pipe. As the pilot gas is distributed upwardly through the pipe and ignited by an electronic pilot generator located inside the pipe adjacent to the pilot openings, the plates are positioned partially over the outlet of the flare stack and the issuing gas ignited. Still another flare ignitor is manufactured by Flare Industries, Inc., of Austin, Tex. The flare ignitor is characterized by an electronic ignitor head which produces a spark for igniting the waste gas and is mounted on the upper end of a support rod pivotally and vertically mounted on the flare stack. The ignitor head is extended through an opening provided in a wind deflector mounted on the outlet of the flare stack for igniting the issuing waste gas. Other patents of interest include Italian Pat. No. 430,043; and U.S. Pat. Nos. 2,776,394; 2,777,512; 3,207,953; 3,506,386; 3,536,428; 3,718,425; 4,121,419; 4,215,979; 5,062,791; 5,160,256; 5,462,431; and my U.S. Pat. No. 5,938,426.

[0006] One of the limitations of flare ignitors which utilize a spark to ignite waste gases in an offshore setting is that the spark is only intermittently generated in the ignitor. Frequently, the offshore flare ignitor remains unattended for long periods of time, and thus an operator is unavailable to time the production of the spark in the flare ignitor with the sporadic and intermittent release of waste gas from the flare stack. Consequently, unignited waste gas has a tendency to escape from the flare stack during those periods in the ignition cycle when the spark is extinguished.

[0007] Accordingly, an object of this invention is to provide a new and improved, pilotless flare ignitor which is capable of preventing the escape of unignited waste gas from a flare stack.

[0008] Another object of this invention is to provide a pilotless flare ignitor which continually produces a spark for igniting waste gas issuing from the outlet of a flare stack.

[0009] Still another object of this invention is to provide a pilotless flare ignitor which may include an ignitor housing having an open end which extends into a flare stack, within which ignitor housing is contained at least two pairs of electrodes each defining a spark gap in which a spark is intermittently generated by operation of a timer, such that a spark of controlled duration repeatedly and continually alternates among the spark gaps of the multiple electrode pairs in order to provide a continually-present spark in the ignitor housing for igniting waste gas issuing either continually or sporadically and intermittently from the flare stack.

SUMMARY OF THE INVENTION

[0010] These and other objects of the invention are provided in a new and improved pilotless flare ignitor which can be used for igniting waste gas issuing sporadically or continually from a flare stack. The flare ignitor may include an ignitor housing, an open end of which extends through the wall of the flare stack into the stream of issuing gas. At least two pairs of electrodes are mounted in the ignitor housing. The electrodes of each electrode pair define a spark gap in which a spark of controlled duration is intermittently generated, and the spark is continually alternated from one electrode pair to the other electrode pair or pairs to provide continuous ignition capability to the flare ignitor and ignite gas issuing at any time from the flare stack.

BRIEF DESCRIPTION OF THE DRAWING

[0011] The invention will be better understood by reference to the accompanying drawing, wherein:

[0012] FIG. 1 is a perspective view of the ignitor housing element of an illustrative embodiment of the pilotless flare ignitor of this invention, extending horizontally through an opening provided in the wall of a vertical flare stack;

[0013] FIG. 2 is a sectional view, taken along section lines 2-2 in FIG. 1 of the pilotless flare ignitor, more particularly illustrating an electrode assembly provided in the ignitor housing and an illustrative wiring scheme for the electrodes, transformer and timer elements of the flare ignitor;

[0014] FIG. 3 is a top view, partially in section, of the burner end of the ignitor housing;

[0015] FIG. 4 is a front view of the burner end of the ignitor housing; and

[0016] FIG. 5 is a front perspective view of the electrode assembly of the pilotless flare ignitor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Referring initially to FIGS. 1-5 of the drawings, an illustrative embodiment of the pilotless flare ignitor of this invention is generally illustrated by reference numeral 1. The pilotless flare ignitor 1 may include a substantially L-shaped ignitor housing 2, typically constructed from stainless steel square tubing and characterized by an open-ended, horizontal ignitor head 4, having a substantially U-shaped cross-sectional configuration, as illustrated in FIG. 4, and the open burner end of which extends through an ignitor opening 16 provided in the wall of a flare stack 15, as illustrated in FIGS. 1 and 3, adjacent to the outlet (not illustrated) thereof. As particularly illustrated in FIGS. 4 and 5, an electrode assembly 6 provided in the ignitor head 4 of the ignitor housing 2 includes a pair of parallel first electrodes 7, extending from one end of an insulator 9 of the electrode assembly 6 and having facing electrode ends 7a, that define a diagonally-oriented spark gap 7b. A pair of parallel second electrodes 20, typically shorter than the first electrodes 7, respectively, also extends from the insulator 9, and the second electrodes 20 have facing electrode ends 20a that define a diagonally-oriented spark gap 20b, as further illustrated in FIGS. 4 and 5. The first electrodes 7 and the second electrodes 20 typically extend horizontally through the insulator 9 of the electrode assembly 6, and the spark gap 7b between the first electrodes 7 and the spark gap 20b between the second electrodes 20 are each diagonally disposed at about a 45-degree angle with respect to the horizontal and vertical, between the ends of the first electrodes 7 and second electrodes 20, respectively. The insulator 9 is constructed of ceramic or other suitable electrically-insulating material and may be removably mounted in the ignitor housing 2 and serves to insulate the first electrodes 7 and second electrodes 20. The first electrodes 7 and the second electrodes 20 are capable of igniting waste gas issuing upwardly through the flare stack 15, as hereinafter further described.

[0018] As illustrated in FIG. 2, the ignitor housing 2 further includes a wiring conduit 3, which extends downwardly from the rear end of the ignitor head 4 and through which wiring conduit 3 two sets of wiring 10 passes, one set of wiring 10 connecting the pair of first electrodes 7 to a first 5000 VAC transformer 11 for generating a spark between the pair of first electrodes 7, as hereinafter further described. The other set of wiring 10 connects the pair of second electrodes 20 to a second 5000 VAC transformer 18 for generating a spark between the pair of second electrodes 20. As further illustrated in FIG. 2, additional wiring 10a connects a timer 12 to the first transformer 11 and to the second transformer 18, respectively, according to the knowledge of those skilled in the art. The timer 12 is, in turn, connected to an A/C power source (not illustrated). An electrode access cover 13, which may have a cover bevel 14 and lip 8 on the burner end thereof, may be hingedly mounted on the ignitor head 4 at the rear edge thereof by means of a hinge 13a, to facilitate accessing the electrode assembly 6 in the ignitor head 4, as illustrated in FIGS. 1 and 2. Pin openings 2a in the ignitor head 4 and in the electrode access cover 13, respectively, coincide to receive a housing pin 2b that secures the electrode access cover 13 on the ignitor head 4. As illustrated in FIGS. 2 and 3, one or multiple gas openings 5 and one or multiple air openings 5a may be provided in the bottom surface of the ignitor head 4 in a selected pattern, to facilitate entry of the upwardly-flowing waste gas and air, respectively, into the ignitor head 4 for contact with a spark intermittently and alternately generated between the diagonally-oriented electrode ends 7a of the pair of first electrodes 7 and the diagonally-oriented electrode ends 20a of the pair of second electrodes 20.

[0019] In operation, the waste gas flows upwardly through the flare stack 15 and enters the ignitor head 4 of the ignitor housing 2 through the gas opening or openings 5 and the open, extending end of the ignitor head 4. Air outside the flare stack 15 flows into the ignitor head 4 through the air opening or openings 5a, and the cover bevel 14 facilitates efficient mixing of the air and waste gas as the upward-flowing waste gas stream inside the flare stack 15 strikes the projecting lip 8 at the top of the cover bevel 14. Operation of the timer 12 causes energizing of the first transformer 11, typically for a period of approximately five seconds, and the first transformer 11 generates a spark of the same duration between the diagonal electrode ends 7a of the pair of first electrodes 7 in the ignitor head 4. Any gas issuing through the flare stack 15 and contained in the ignitor head 4 is immediately ignited and further ignites the waste gas flowing upwardly in the flare stack 15. Accordingly, the burning waste gas is substantially confined to the area of the flare stack 15 which is located above the ignitor head 4, thus reducing the heat applied to the ignitor head 4, lengthening the life of the electrode assembly 6 and eliminating the necessity for pivoting the ignitor head 4 from the flare stack 15. Immediately after de-energizing the fist transformer 11, the timer 12 energizes the second transformer 18, typically for a period of approximately five seconds, and the second transformer 18 generates a spark of the same duration between the electrode ends 20a of the pair of second electrodes 20. Any gas issuing through the flare stack 15 and contained in the ignitor head 4 is immediately ignited and further ignites the waste gas flowing upwardly in the flare stack 15. Immediately after de-energizing the second transformer 18, the timer 12 again energizes the first transformer 11 to generate a spark between the first electrodes 7 and repeat the cycle. In the foregoing manner, the first electrodes 7 and the second electrodes 20 are repeatedly and alternately energized to continually produce a spark in the ignitor head 4 and facilitate igniting and burning any waste gas issuing from the flare stack 15 at any time. Accordingly, all gas issuing from the flare stack 15, whether in a continuous or a sporadic, unpredictable fashion, will be ignited by the spark generated between either the first electrodes 7 or the second electrodes 20, since a spark alternately produced by the first electrodes 7 and the second electrodes 20, respectively, is continually present in the ignitor head 4. The ignitor housing 2 prevents wind, rain or other influences from hindering ignition of the waste gas in the flare stack 15, since the ignitor head 4 remains in the flare stack 15. Replacement of the first electrodes 7, the second electrodes 20 or other components of the ignitor head 4 may be effected by removing the housing pin 26 from the pin openings 2a and pivoting the electrode access cover 13 from the closed position illustrated in FIG. 4 to the open position illustrated in FIG. 1 and in phantom in 2, to remove the electrode assembly 6.

[0020] It is understood that two or more pairs of electrodes can be provided in the ignitor head 4 of the ignitor housing 2 for alternately and continually generating a spark in the ignitor head 4 and igniting continually or sporadically-flowing waste gas in the flare stack 15. It is farther understood that any number of gas openings 5 and air openings 5a can be provided in the ignitor head 4 of the ignitor housing 2 in any selected pattern to facilitate gas and air entry, respectively, into the ignitor head 4.

[0021] While the preferred embodiments of the invention have been described above, it will be recognized and understood that various modifications may be made in the invention and the appended claims are intended to cover all such modifications which may fall within the scope and spirit of the invention.

Claims

1. A pilotless flare ignitor for igniting waste gas issuing from a flare stack, said pilotless flare ignitor comprising:

an ignitor housing having an open end for extending into the flare stack;

at least two pairs of electrodes provided in said ignitor housing for producing respective sparks each having a selected duration in said ignitor housing and igniting the waste gas in said ignitor housing and the flare stack; and

a timer connected to said at least two pairs of electrodes, respectively, for controlling the selected duration of the respective sparks and repeatedly alternating the sparks between one of said at least two pairs of electrodes and the other of said at least two pairs of electrodes.

2. The pilotless flare ignitor of claim 1 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

3. The pilotless flare ignitor of clam 1 comprising at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing.

4. The pilotless flare ignitor of claim 3 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

5. The pilotless flare ignitor of claim 1 comprising at least one air opening provided in said ignitor housing for positioning outside the flare stack and facilitating flow of air into said ignitor housing.

6. The pilotless flare ignitor of claim 5 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

7. The pilotless flare ignitor of claim 5 comprising at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing.

8. The pilotless flare ignitor of claim 7 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

9. The pilotless flare ignitor of claim 5 wherein said at least one air opening comprises a plurality of air openings.

10. The pilotless flare ignitor of claim 9 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

11. The pilotless flare ignitor of claim 9 comprising at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing.

12. The pilotless fare ignitor of claim 11 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

13. A pilotless flare ignitor for igniting waste gas issuing from a flare stack, said pilotless flare ignitor comprising:

an ignitor housing having an open end for extending into the flare stack;

at least two pairs of electrodes provided in said ignitor housing for producing respective sparks each having a selected duration in said ignitor housing and igniting the waste gas in said ignitor housing and the flare stack;

a timer connected to said at least two pairs of electrodes, respectively, for controlling the selected duration of the respective sparks and repeatedly alternating the sparks between one of said at least two pairs of electrodes and the other of said at least two pairs of electrodes; and

wherein each of said at least two pairs of electrodes is disposed in a plane oriented in angular relationship with respect to a horizontal plane.

14. The pilotless flare ignitor of claim 13 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

15. The pilotless flare ignitor of claim 13 comprising at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing.

16. The pilotless flare ignitor of claim 15 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

17. The pilotless flare ignitor of claim 13 comprising at least one air opening provided in said ignitor housing for positioning outside the flare stack and facilitating flow of air into said ignitor housing.

18. The pilotless flare ignitor of claim 17 comprising an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes.

19. The pilotless flare ignitor of claim 17 comprising at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing.

20. A pilotless flare ignitor for igniting waste gas issuing from a flare stack, said pilotless flare ignitor comprising:

an ignitor housing having an open end for extending into the flare stack;

at least two pairs of electrodes provided in said ignitor housing for producing respective sparks each having a selected duration in said ignitor housing and igniting the waste gas in said ignitor housing and the flare stack;

a timer connected to said at least two pairs of electrodes, respectively, for controlling the selected duration of the respective sparks and repeatedly alternating the sparks between one of said at least two pairs of electrodes and the other of said at least two pairs of electrodes;

wherein each of said at least two pairs of electrodes is disposed in a plane oriented in angular relationship with respect to a horizontal plane;

an access cover carried by said ignitor housing for providing access to said at least two pairs of electrodes;

at least one gas opening provided in said ignitor housing for positioning inside the flare stack and facilitating flow of waste gas into said ignitor housing; and

at least one air opening provided in said ignitor housing for positioning outside the flare stack and facilitating flow of air into said ignitor housing.