US3583851A

US3583851A - Ignition devices

Info

Publication number: US3583851A
Application number: US824201A
Authority: US
Inventors: Ernest W Harrington; Albert E Proctor
Original assignee: Flaregas Engineering Ltd
Current assignee: Airoil Flaregas Ltd
Priority date: 1968-12-17
Filing date: 1969-05-13
Publication date: 1971-06-08
Anticipated expiration: 1988-06-08
Also published as: ES366796A1; FR2026302A1; DE1919247A1; GB1227870A; DE1919247C3; DE1919247B2

Abstract

An ignition device for igniting a pressurized air and gas mixture especially for use in conjunction with a flare and having a rod member axially moveable within a housing, the member has a frictional surface against which a spark-producing element is biased by a spring so that movement of the member will ignite a pressurized air and gas mixture in the vicinity of the element. An installation incorporating the ignition device has means for reducing the velocity of the air and gas mixture in the vicinity of the spark-producing element to ensure that the device will reliably effect ignition.

Description

United States Patent Appl. No. Filed Patented Assignee Priority IGNlTlON DEVICES 8 Claims, 5 Drawing Figs.

US. Cl 431/274 Int. l F234] 2/16 Field of Search 43ll273- Primary Examiner-Edward J. Michael Attorney-Sughrue, Rothwell, Mion, Zinn & Macpeak ABSTRACT: An ignition device for igniting a pressurized air and gas mixture especially for use in conjunction with a flare and having a rod member axially moveable within a housing, the member has a frictional surface against which a sparkproducing element is biased by a spring so that movement of the member will ignite a pressurized air and gas mixture in the vicinity of the element. An installation incorporating the ignition device has means for reducing the velocity of the air and gas mixture in the vicinity of the spark-producing element to ensure that the device will reliably effect ignition.

PATENTED JUN 8 I97! SHEET 3 OF 3 IGNITION nsvrcss BACKGROUND OF THE INVENTION Large quantities of combustible waste or dump gases are usually disposed of in the oil and chemical industries by burning the gases in a structure known as a flare. Due to the hazardous nature of the operation of burning these gases these flares are usually situated in remote parts of the oil or chemical plant. In order to reliably ignite the waste gas whenever desired it has been known to provide a plurality of separate pilot burners each fed with a pressurized air and gas mixture. This air and gas mixture is ignited and the pilot burners thereby bring about ignition of the main dump gas emerging from the flare. To ignite the air gas mixture fed to a pilot burner it is known to use an electrically operated sparking plug. The sparking plug is provided in a pipe or chamber into which the pressurized air and gas is supplied. A spark is initiated in the spark plug by an electrical voltage to ignite the moving gas/air mixture. A travelling flame front is thus produced which emerges from one of the pilot burners arranged near the outlet of the flare to thereby ignite the main bulk of the waste gas.

Usually, three or four pilot burners are arranged around an outlet of the flare and a distributor is provided which distributes the combusting gas and air mixture to each of the pilot burners in turn.

Due to stringent regulations governing the use of electrical apparatus and general ignition articles or apparatus in oil and chemical plants, the known ignition devices and especially the associated electrical supply cables are usually rendered fireproof and explosionproof. This greatly increases the cost of the known ignition devices since the cables must be provided over considerable distances to the location of the flare.

Other devices have also been known for initiating combustion of the air/gas mixtures, such as piezoelectric devices, but generally speaking these devices have not proved wholly satisfactory and have not been used to any great extent. Moreover it has been found that weather conditions adversely affect the performance of these other devices.

A general object of the present invention is to provide an improved ignition device for use with flares.

SUMMARY OF THE INVENTION According to the present invention there is provided an ignition device for igniting a pressurized combustible air and gas mixture in a chamber, said device comprising a. a housing,

b. a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface,

c. a detachable spark-producing element adjacent said chamber and d. a spring biasing said element into engagement with said frictional surface so that when the rod member is displaced axially the frictional engagement between the spark-producing element and the frictional surface will produce incandescent particles from the element which will ignite a pressurized air and gas mixture in the vicinity thereof.

According to a further feature of the invention a detachable cylindrical part in screw-threaded engagement with an aperture in the housing, said cylindrical part having an axis extending nonperpendicularly to the axis of the rod member with the inward projection of the axis of said part intersecting the axis of the rod member in the region of the spark-producing element, and a transparent viewing window detachably secured to the upper end of said part to allow visual inspection of the spark-producing function of said element.

Further according to the invention there is provided an installation for igniting a pressurized combustible air and gas mixture, said installation having i. a member with a. a first inlet for receiving ressurized air,

b. a second inlet for receiving pressurized gas, and

c. an outlet communicating with said inlets, and

ii. an ignition device comprising:

a. a housing,

c. a detachable spark-producing element disposed so that the spark-producing element is subjected to contact from the gas/air mixture from the inlets and d. a spring biasing said element into engagement with said frictional surface so that when the rod member is displaced axially the frictional engagement between the spark-producing element and the frictional surface will produce incandescent particles from the element, and

iii. means for reducing the velocity of the gas/air mixture in the vicinity of said element.

Various other aspects and features of the present invention will become more apparent from consideration of a constructional embodiment thereof.

BRIEF DESCRIPTION OF DRAWINGS A constructional embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings wherein:

FIG. I is a plan view of a device made in accordance with the present invention;

FIG. 2 is a longitudinal section taken along the line A-A of FIG. 1;

FIG. 3 is a cross section taken along the line 5-3 of FIG. 1;

FIG. 4 is a diagrammatic side view of the device when incorporated in an installation panel; and

FIG. 5 is a diagrammatic side view of the installation panel of FIG. 4 showing the connection to the pilot burners of a flare.

DESCRIPTION OF PREFERRED EMBODIMENT As shown in FIGS. 1 to 3 the device has a main housing 10 in the form of a cylinder with one end 11 receiving a rodlike member 12. The member 12 can slide to and fro along its longitudinal axis and one or more bearing rings 30, 31 are provided between a radially innermost wall 32 of the housing 10 and the member 12 to guide the latter. An abutment ring 13 in the form of a circlip is provided on the member 12 to prevent the member 12 from being withdrawn from the housing 10. The end of the member 12 disposed outside the housing 10 is attached to a member 14 with a domelike structure suitable for engagement by the palm of the hand. A further abutment ring 33 is provided on the inner face of the member 14 to delimit the movement of the member 12 into the housing 10. As shown in FIG. 2 the end of the housing 10 nearest the member 14 is provided with a widened aperture 34 which receives the axial part 35 of the member 14 when the member 12 is urged fully into the housing 10. The axial part 35 of the member 14 has a circumferential groove 36 which receives a corresponding projection 37 in the form of a pin 61 extending through the housing 10 thereby providing a positive location for the member 14 when the member 12 is urged inwardly of the housing 10. The pin 61 serves to prevent the device from being operated by maintaining the member 12in its innermost position and preventing its movement outwardly of the housing 10.

A plate 38 is provided at the inner end of the aperture 34 and the ring 33 can engage this plate 38. The plate 38 can be detachably secured to a radial portion 39 of the housing 10, as by screws 40. A recess 41 is cut into the portion 39 adjacent the plate 38 and this recess 41 accommodates a sealing ring 42 engaging the peripheral surfaces of the member 12.

The other end 11' of the housing 10 is provided with a threaded extension 15 coaxial with the member 12 and this extension 15 serves for engagement in a threaded aperture of a further member (not shown) in FIGS. 1 to 3 constituting a chamber for a combustible gas mixture. The outer surface of the rod member 12 over a portion 12' disposed within the housing 12 is provided with a frictional or roughened surface having projections or the like. The frictional portion 12' can conveniently be threaded.

A hollow cylindrical part 17 with a main bore 24 has an outer screw thread at one end which engages with a corresponding screw thread in an aperture 18 provided in the housing 10. A sealing ring 46 is provided between an end wall 47 of the part 17 and the housing 10. The axis of the aperture 18 extends substantially perpendicularly to the axis of the member l2. The upper end of the part 17 is provided with a further screw-threaded portion 19 which receives the internal screw thread of a cap 20; a further sealing ring 48 being provided between mating end walls of the

parts

17, 20. A sparkproducing element 21 is held within a plug 45 engaging an end of a compression spring 22 which lies in the main bore 22 coaxial with the threaded aperture 18. The other end of the spring 22 engages on the end radial surface 25 of the cap 20. Thus, the element 21 is biased by the spring 22 into frictional engagement with the frictional surface 12' of the rod member 12.

A further cylindrical part 26 has an outer screw thread in an oblique aperture 27 provided in the housing 10. As shown, the axis of the aperture 27 and of the part 26 extend obliquely i.e. nonperpendicularly to the axis of the member 12. The part 26 has an enlarged portion 50 which seats in an oblique recess 51 in the outer wall of the housing and a sealing ring 52 is provided between the mating end walls of the portion 50 and the recess 51. The projection of the axis of the part 26 intersects the axis of the member 12 somewhere in the region of the spark-producing element 21. The upper end of the part 26 is provided with a transparent viewing window 28. The visual aspect of the window 28 is such as to allow someone to view the spark-producing function of the element 21 when the device is operated.

The operation of the device is basically simple and largely self explanatory. The rod member 12 is extended out of the housing in the direction of arrow X of FIG. 2 and when it is required to produce a spark the member 12 is urged inwardly of the housing 10 in the direction of arrow Y of FIG. 2 with a quick movement preferably effected by the palm of the hand. The frictional engagement between the frictional outer surface 12' of the member 12 and the spark-producing element 21 produces particles of incandescent material from the element 21 which particles serve to ignite a gas/air mixture in the member to which the device is adjoined i.e. by the extension 15. When the rod member 12 is withdrawn from the housing 10 again in the direction of arrow X and the device is ready for further operation. As an operator urges the rod member 12 inwardly of the housing 10 he can observe through the window 28 whether or not a spark is being produced by the element 21.

Due to the strict regulations prevailing in oil and chemical plants utilizing combustible substances and governing the use of any article which could initiate combustion, the ignition device itself and the element 21 would probably constitute a tire risk since it could produce a spark. For this reason it is desirable for there to be a means of ensuring that the device cannot be operated by unauthorized persons or removed from the associated conduit 16, or equivalent part in an installation, unless the element 21 is firstly removed. Although not illustrated a simple locking device which performs the function of preventing removal of the device can be incorporated on the

parts

16, 17 of FIG. 1. To this end an interengageable lug and abutment ring provided on these parts could be used to prevent the housing from being rotated to unscrew the device from the associated conduit unless the part 17 is removed. The pin 61 is shown in FIGS. 1 to 3 as receiving a chain 62 and a padlock 63 which can be used to prevent the pin 61 from being removed from the device. As mentioned before the pin 61 prevents the device from being operated and only by removing the pin 61 can the device be rendered operative.

An example of an installation employing the device made in accordance with the invention is shown in FIG. 4. As shown the device of FIGS. 1 to 3 generally designated is placed into a bypass channel 16 so that the part 15 of the housing 10 engages into the channel 16 constituting the aforementioned member. The channel 16 is formed in a one-piece member 81 also containing a main channel 81'. A gas supply pipe 82 passes via inter alia a manually adjustable on-off valve 82', a pressure control valve 83 and a pressure gauge 84 to a first inlet 85 of the part 81. Likewise a compressed air supply pipe 86 passes via inter alia a manually adjustable on-off valve 86', a pressure control valve 87 and a pressure gauge 88 to a second inlet 89 of the part 81.

It is necessary for the air supply to be a pressure somewhat in excess of that of the gas in order to reliably drive a flame front produced by the ignition device to a pilot burner which as is known can be at the exit of a flare stack of relatively great height. Typical pressures would be l0-50 p.s.i. for the air and about 5 p.s.i. for the gas which can be any reliable hydrocarbon, for example butane. For this reason, i.e. due to the velocity of the gas and air mixture, the mixture cannot be ignited directly by the device shown in FIG. 1 since the velocity of the mixture will prevent local heating produced by the incandescent particles of the element 21 from raising the temperature of the mixture to the desired extent, to reliably ensure combustion. Thus, some means must be adopted to reduce the velocity of the gas and air mixture. In FIG. 4 this is accomplished by the provision of the bypass channel 16. The gas and air mixture is brought together in the member81 and the mixture flows through the main channel 81' and through the bypass channel 16. The provision of the bypass channel 16 reduces the velocity of the gas and air mixture passing therethrough and ignition can occur in the bypass conduit 16 upon appropriate actuation of the device 30. The new combusted mixture in the outlet of channel 16 is brought together with the gas and air mixture in the main channel 81 to form a complete flame front which is forced to one of the pilot burners at the exit of the flare.

The outlet of the member 81 can feed a distributor generally designated 90 by means of which the outlet from the part 31 can be brought selectively into communication with supply pipes connected to pilot burners.

The provision of the bypass channel is only one-way in which the velocity of the gas/air mixture near the sparkproducing element can be reduced and other means for doing this can be envisaged such as gas shields partly surrounding the element and effectively defining a subsidiary chamber functionally equivalent to the bypass channel.

FIG. 5 depicts diagrammatically the installation of FIG. 4 with an associated flare. The common parts shown in FIGS. 4 and 5 are denoted with the same reference numerals.

The flare is provided with three pilot burners 91 around its outlet 92. Waste gas for disposal is supplied to the flare 60 from a feed pipe 101. Each burner 91 has a feed conduit 97 connected to an outlet of a multi-outlet distributor 90. The distributor 90 is operated by hand to bring the outlet of the member 81 into selective communication with each conduit 97. In this way the distributor 90 can feed a gas/air mixture to each burner 91 and the device 80 can be operated to ignite the mixture emerging from the particular burner in question.

We claim:

1. An assembly for igniting a pressurized combustible air and gas mixture, said assembly comprising the combination of;

a first inlet for receiving pressurized air;

a second inlet for receiving pressurized gas;

a main channel communicating with said first and second inlets;

a bypass channel communicating with said main channel;

an outlet communicating with said main and bypass channels;

an ignition device operably disposed within said bypass channel; said ignition device comprising a housing, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface; said device further comprising a spark-producing element, and a spring biasing said element into engagement with said frictional surface so that axial displacement of the rod member will ignite the pressurized gas and air mixture in the bypass channel to thereby produce a flame front at said outlet.

2. An assembly according to claim 1, wherein said bypass channel extends substantially perpendicularly to the axis of the rod member.

3. An assembly according to claim 1, wherein the ignition device further comprises a detachable cylindrical part in screw-threaded engagement with an aperture in the housing thereof, said cylindrical part having an axis which is inclined relative to the axis of the rod member so that an inward projection of the axis of said part intersects the axis of the rod member in the region of the spark-producing element, said cylindrical part being provided with a transparent viewing window to allow .visual inspection of the spark-producing function of said element.

4. An assembly according to claim 1, wherein the sparkproducing element is disposed within a hollow part in screwthreaded engagement with an aperture in the housing of the ignition device.

5. An assembly for igniting a pressurized combustible air and gas mixture, said assembly comprising the combination of:

a first inlet for receiving pressurized air;

a second inlet for receiving pressurized gas;

an outlet communicating with said inlets;

an ignition device which comprises a housing,

a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface;

the ignition device further comprising a spark-producing element disposed to be contacted by the gas/air mixture from the inlets and a spring biasing said element into engagement with the frictional surface so that axial displacement of the rod member will ignite said mixture in the vicinity of the element; the assembly being provided with means for reducing the velocity of the mixture in the vicinity of the element to promote such ignition.

6. An assembly according to claim 5, wherein the ignition device further comprises a detachable cylindrical part in screw-threaded engagement with an aperture in the housing thereof, said cylindrical part having an axis which is inclined relative to the axis of the rod member so that :an inward projection of the axis of said part intersects the axis of the rod member in the region of the spark-producing element, said cylindrical part being provided with a transparent viewing window to allow visual inspection of the spark-producing function of said element.

7. An installation comprising a flare stack tip having pilot burners arranged around the outlet thereof:

a manually operated multi-outlet distributor feeding said pilot burners;

a member having a first inlet for receiving pressurized air, a second inlet for receiving pressurized gas, a main channel communicating with said inlets, a bypass channel communicating with said main channel, an outlet communicating with said main and bypass channels and with said distributor; said installation further comprising an ignition device operably disposed within the bypass channel of said member; said ignition device comprising a housing, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface; said device further comprising a spark-producing element, and a spring biasing said element into engagement with said frictional surface so that axial displacement of the rod member will ignite the pressurized gas and air mixture in the b pass channel to thereby produce a flame front at the out et of said member which can be conveyed to said pilot burners via the distributor.

8. An installation comprising a flare stack tip, having pilot burners arranged around the outlet thereof; a manually operated multi-outlet distributor feeding said pilot burners; a member having a first inlet for receiving pressurized gas, and an outlet communicating with said inlets and with said distributor; said installation further comprising an ignition device composed of a housing connectable to said member, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface, the ignition device further comprising a spark-producing element disposed to be contracted by the gas/air mixture from the inlets of said member and a spring biasing said element into engagement with the frictional surface so that axial displacement of the rod member will ignite said mixture in the vicinity of the element to thereby produce a flame front at the outlet of said member which can be conveyed to said burners via the distributor; there being further provided means for reducing the velocity of the gas/air mixture in the vicinity of the element to promote ignition of the mixture.

Claims

1. An assembly for igniting a pressurized combustible air and gas mixture, said assembly comprising the combination of: a first inlet for receiving pressurized air; a second inlet for receiving pressurized gas; a main channel communicating with said first and second inlets; a bypass channel communicating with said main channel; an outlet communicating with said main and bypass channels; an ignition device operably disposed within said bypass channel; said ignition device comprising a housing, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface; said device further comprising a spark-producing element, and a spring biasing said element into engagement with said frictional surface so that axial displacement of the rod member will ignite the pressurized gas and air mixture in the bypass channel to thereby produce a flame front at said outlet.

3. An assembly according to claim 1, wherein the ignition device further comprises a detachable cylindrical part in screw-threaded engagement with an aperture in the housing thereof, said cylindrical part having an axis which is inclined relative to the axis of the rod member so that an inward projection of the axis of said part intersects the axis of the rod member in the region of the spark-producing element, said cylindrical part being provided with a transparent viewing window to allow visual inspection of the spark-producing function of said element.

4. An assembly according to claim 1, wherein the spark-producing element is disposed within a hollow part in screw-threaded engagement with an aperture in the housing of the ignition device.

5. An assembly for igniting a pressurized combustible air and gas mixture, said assembly comprising the combination of: a first inlet for receiving pressurized air; a second inlet for receiving pressurized gas; an outlet communicating with said inlets; an ignition device which comprises a housing, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface; the ignition device further comprising a spark-producing element disposed to be contacted by the gas/air mixture from the inlets and a spring biasing said element into engagement with the frictional surface so that axial displacement of the rod member will ignite said mixture in the vicinity of the element; the assembly being provided with means for reducing the velocity of the mixture in the vicinity of the element to promote such ignition.

6. An assembly according to claim 5, wherein the ignition device further comprises a detachable cylindrical part in screw-threaded engagement with an aperture in the housing thereof, said cylindrical part having an axis which is inclined relative to the axis of the rod member so that an inward projection of the axis of said part intersects the axis of the rod member in the region of the spark-producing element, said cylindrical part being provided with a transpareNt viewing window to allow visual inspection of the spark-producing function of said element.

7. An installation comprising a flare stack tip having pilot burners arranged around the outlet thereof: a manually operated multi-outlet distributor feeding said pilot burners; a member having a first inlet for receiving pressurized air, a second inlet for receiving pressurized gas, a main channel communicating with said inlets, a bypass channel communicating with said main channel, an outlet communicating with said main and bypass channels and with said distributor; said installation further comprising an ignition device operably disposed within the bypass channel of said member; said ignition device comprising a housing, a rod member mounted in the housing for movement back and forth therein in an axial direction, the rod member having at least a portion of its outer surface formed as a frictional surface; said device further comprising a spark-producing element, and a spring biasing said element into engagement with said frictional surface so that axial displacement of the rod member will ignite the pressurized gas and air mixture in the bypass channel to thereby produce a flame front at the outlet of said member which can be conveyed to said pilot burners via the distributor.