US2668592A - Gas burner and method for burning gas in oil and gas wells - Google Patents

Description

Feb. 9, 1954 J. J. PlRos ET AL GAS BURNER AND METHOD FOR BURNING GAS IN OIL AND GAS WELLS Filed June 4, 1949 el! @ma TToRNEYs Patented Feb. 9, 1954 GAS BURNER AND METHOD FDR BURNING GAS IN QIL AND GAS .WELLS long .period of time, which may amount to many months, and Which is situated at the end of a tubing string that may be many hundreds or thousands of feet in length, must be reliable. And quite obviously, the combustion space for its operation is very limited and the pressures relatively high'. In addition, serious problems obtain in controlling the temperature below that which.

of drilling expense, rarely exceeds a diameter suicient to accommodate '7" O. D. pipe. We have found, however, that our burning system, constructed to enter a 4 O. D. pipe, ignites with a gas and air feed corresponding to a heat release of 600,000 B. t. u per hour under bottom-hole operating conditions.

A useful burner exemplifying our invention is illustrated somewhat diagrammatically in the accompanying drawing in which:

Fig. 1 is a cross-section of a combustible gas burner embodying the principles of our discovery.

Fig. 2 is an enlarged view of the mixing plate of said burner taken along the line 2-2.

Fig. 3 is a fragmentary view of Fig. 1 illustrating a method for obtaining limited pre-mixture of air and gas between the mixing plate and the point of ignition.

The construction of `the `burner is advantageously of stainless steel, or other heat resistant alloy calculated to withstand extreme conditions of temperature and pressure. As represented in Fig. 1 the burner is composed of two sections of 2" standard stainless steel pipe, section I0 constituting the section II containing the 'combustion elements. Combustion chamber I0 is of a length designed to accommodate the turbulent flame and in the embodiment illustrated is II is of similar length and, as shown, is joined to chamber I0 by stainless steel coupling I2.

Situated at the head of combustion chamber I0 isf a mixing plate I3 which, in the embodiment shown, is of stainless steel, welded in place.

Mixing plate I3 contains three s-inch diameter ducts, air ducts I4 and I5 and gas duct yI5 (refer to Fig. 2), each drilled at a 30 by 30 compound angle with respect to the center line of the mixing plate. The ducts may be geometrically positioned in plate I3, but air ducts I4 and I5 are shown as advantageously spaced closely adjacent to gas duct I6 so `as 'to sandwich it in order to improve mixing. The fuel-air mixture is ignited by spark plug I'I centrally located in mixing plate I3. Plug I'I is mounted in nipple I8 which is Welded to hexagonal I9 of plug i1, and is joined by coupling 24 to inner pipe 20 which extends the length of pipe section II and provides a protective sheath for high tension cable 2l leading to plug I1.

Fuel gas is admitted to the burner through pipe and vat a point -well above the combustion zone and is diverted to separate gas line 22, advantageously constructed of steel tubing sections joined by coupling A2?, which leads directly to gas duct I6 of mixing plate I3.

Air enters the burner Athrough pipe section II in 75 a high velocity stream surrounding and tending elongated combustion chamber and' 24 inches. Pipe section li by 55s-inch stainlessV to cool inner pipe 20 and gas line 22, and passesl through air ducts I4 and I5 which impart a whirling tangential motion to the flame by reason of their compound angular construction.

In the modification of Fig. 3, limited pre-mixture of gas and lair is achieved by providing a spiral vane 25 leading from the'I discharge of the gas and air ports so as to cause all the gas and air to pass under the vane before spilling into the combustion zone. The spiral vane is a single turn helix 25 as shown, which may be constructed of stainless steel, and which is welded to the outside of internal cylinder 26. Cylinder 26 is welded around spark plug points 21 and seals spiral vane 25 o-n the inside. `Spiral vane 25 is advantageously Welded to mixing plate I3 at a point just behind the first air duct, thus causing all the gas and air to pass underneath vane 25 before entering the combustion Zone. In order to supply a small portion of the pre-mixed gas and air to the spark plug igniter, small scoop 28 is formed out of the wall of cylinder 2S advantageously at a point where the gas and air perfect combustion, 1s supplied through the extensions of outer pipe section II at pressuresquantities necessary for the release. The fuel and air are mixed at the mixing plate by discharge from angularly directed ducts I4, I5, IIB. The mixture is ignited at a pressure of about 40 to 50 p. s. i. g. by electric spark from spark plug I1 which is regulated by gas desired rate of heat controlled from vthe surface through cable 2|,l

properly extended. The flame temperature is controlled by admitting secondary air through the tubing or outer case. In this manner, high rates of heat release are achieved under the subterranean combustion conditions while soot pro-` oil structure duction that might clog the porous is obviated.

For example, a burner of the type shown in Fig. l but with the ducts positioned 108 from each other was placed in a pressure tight 4 casing. When propane gas and air were fed to the burner in theoretically correct proportion for perfect combustion, plus enough air feed to the casing to limit the resulting temperature to 1500 F., the burner ignited at 40 p. s. i. g. We found that the pressure could be built up to p. s. i. g. while maintaining combustion. rIhe pressure was maintained on the casing by using a valve to pinch down on the ue gas bled out of the casing. Once the higher pressure, the pressure on the casing could be reduced to a value slightly above atmospheric and the combustion still maintained. This test was conducted at a gas feed rate sufficient to give about 500,000 B. t. u. per hour dissipation.

We found however that it was not possible to ignite such Accordingly, for operation at atmospheric pressure it is desirable' to provide a separate gas tube passing through the mixing plate to emerge close to the outlet of each air duct and so arranged that the gas flows directly into the high velocity air burner was ignited at the a burner at atmospheric pressure.-

assetati ment insures explosive mixture @tall points,

down stream from the mixing spiate,

For operation with natural gas., which is chiefly methane, we have found that a burner incur porating a limited pre-mixture system f 'the type shown in Figs. 2 and 3 shows greatly improved ignition behavior. Pre-mixing of gas and air at the spark plug igniter is increased by reducing the spacing between the gas and air ,ducts so as to sandwich the gas duct between the two air ducts and by providing a spiral mixing vane and internal cylinder which together form a mixing passageway from the discharge 4ports of -the lgas and air ducts and opening into -the combustion chamber. The intern-al cylinder is vented or provided 'with a scoop to supply mixture to the igniter at the face of the mixing plate.

We have described our invention in its basic forms which include -a burner characterized by an elongated combustion chamber with a mixing plate at -its head containing separate angularly directed air and -fuel ducts and separate passages for fuel and air to these ports, including a spiral mixing vane with internal cylinder and sidesscoop for eiecting limited pre-mixing prior to the point of ignition; a method of burning fuel gas .under conditions ofl high pressure to obtain high rates of heat release characterized by introducing fuel gas and air separately and angularly to the head of an elongated combustion zone so as to impart a turbulent and whirling tangential motion to the flame resulting from the mixture; and an improvement in thermal methods for recovering oil and gas from oil-bearing formations characterized by burning fuel gas at formation level in an input well in a system wherein fuel gas and air under pressure in approximately theoretical proportion for perfect combustion are separately and angularly introduced to an elongated combustion zone tted within the oil well casing so as to impart a turbulent whirling tangential motion to the tiame resulting from the mixture and controlling the temperature of the flame by introducing secondary air through the oil well casing. There are obvious variations and substitutions, of course, which can be made by those skilled in the art in the number, position and form of mechanical elements involved, the materials and dimensions of the structural elements, the proportioning of air and fuel and control of temperature and soot formation, etc. We contemplate that such changes in form or substitution of equivalents lie within the following claims.

We claim:

l. A gas burner which comprises first means having an elongated, substantially cylindrical wall forming a combustion chamber; second means connected to the head of the combustion chamber for directing streams of fuel gas and air into the combustion chamber in a manner to accomplish mixing therein; third means for separately delivering fuel gas and air to said second means; said second means including means for separately introducing each of said separatestreams of fuel gas and air into the combustion zone at a location spaced from the axis of the combustion chamber and adjacent said cylindrical wall and in a downstream direction having a directional component outward from said axis and a directional component tangential to a circle normal to said axis having its center at said axis and passing through said location, the last named tangential directional component of each of said streams being in the same direction circumferentially of said second means thereby accomthe axis of said chamber and .eeen .duet its passage through ,said plate .in devvnstreemdrees tion having a direetiona1oornponent outward roni said axis and a ydirectional, .component normal to its respective radial plane which passes .through the upstream entrance to said duet. the .last named direetionaleomponent ofeach of 7the duets being in the same direction Inferentially of -tial said plate, thereby accomplishing t swirling and mixing :of the` fuel ,gas t.

,Y i iuel ses and air passages respectively, and eans for igniting the fuel gas-air mixture.

3. A gas burner which comprises an elongated combustion chamber having a longitudinal axis and radial planes along said axis, a mixing plate at the head of said chamber, a fuel gas duct in said plate, a plurality of angularly directed air ducts in said plate sandwiching said gas duct, said ducts being similarly positioned at substantially the same distance from the axis of said chamber and each duct in its passage through said plate in downstream direction having a directional component outward from said axis and a directional component normal to its respective radial plane which passes through said laxis and the upstream entrance to said duct, the last named directional component of each of the ducts being in the same direction circumferentially of said plate thereby accomplishing tangential swirling and mixing of the fuel gas yand air adjacent the wall of the combustion chamber, a gas line feeding said gas duct, a tubular air passage charging said air ducts and containing said gas line, means for supplying fuel gas and air to said gas line and air passage respectively, and means for igniting the fuel gas-air mixture at the face of the mixing plate.

4. A gas burner in accordance with claim 2 and including a cylinder extending downstream from said mixing plate and surrounding said igniting means, and a spiral mixing vane surrounding said cylinder and forming a mixing passage way from said ducts opening into said combustion chamber, said cylinder having a scoop arranged to supply a small portion of the fuel gas-air mixture to said igniting means.

5. In the method of burning fuel gas, the improvement which comprises separately passing fuel gas and air streams to a mixing point at the head of a substantially cylindrical combustion zone, separately introducing each of said streams into the combustion zone at a location spaced from the longitudinal axis of the combustion zone and in a downstream direction having a directional component outward from said axis and a directional component tangential to a circle having its center at said axis and passing through said location, the last named tangential directional component of each of said streams being Vin the same direction circumferentially of saidV zone, directing the flow of said streams in a manner to produce peripheral ow in said combustion zone to accomplish tangential swirling and mix-l ing of the fuel gas and air atthe periphery of said combustion zone, and-igniting the resultant fuel gas-air mixture. Y

6. In the method of producing hot combustion gases at an input well for the' thermal recovery of oil and gas, the improvement which comprises separately passing fuel gas and air streams to a mixing point at the head of a substantially cylindrical combustion zone in said well, separately introducing each of said streams into the combustion zone at a location spaced from the longitudinal axis of the combustion zone and in a downstreamV direction having a directional component outward from said axis and a directional component tangential to a circle having its center at said axis and passing through said location, the last named tangential directional component ofv each of said streams being` in the same direction circumferentially of said zone, directing the flow of said streams in a manner to produce peripheral iiow in said combustion zone to accomplish tangential swirling and mixing of the fuel gas and airat the periphery of said combustion zone, igniting the resultant fuel gas-air mixture, and controlling the temperature of the flame by introducing secondary air into said well and around said combustion zone.

JOHN J. PIROS.

OLIVER F. CAMPBELL.

References Cited in the file of this patent UNITED STATES PATENTS Number l Name Date 686,157 Spinney Nov. 5, 1901 1,231,726 Gault July 3, 1917 1,473,348 Howard Nov. 6, 1923 1,626,940 Kreager May 3, 1927 1,656,907 Bansen Jan. 24, 1928 2,225,775 Garrett, Dec. 24, 1940 2,390,770 Barton et a1. Dec. 1'1, 1945 2,443,259 Martin June 15, 1948 2,444,755 Steffen July 6, 1948 2,473,435 Luzader June 14, 1949 2,500,787- Lelgemann Mar. 14, 1950 2,506,853 Berg et al May 9, 1950 2,511,380 Stadler June 13, 1950 2,561,200 yHess July 17, 195i

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