Methods and apparatus for burning liquid hydrocarbons

Abstract

A method for disposing of liquid hydrocarbons produced during a well test utilizing a burner assembly that includes a cluster of atomizers mounted on the outer end of a boom. The boom is adapted to be attached to the side of an offshore drilling rig. The atomizers are pointed in slightly divergent directions, with each atomizer forming a spray of hydrocarbons that burns along and about a flame line. A water injection system is associated with each atomizer and is provided with nozzles for injecting high velocity sprays of water droplets at low entry angle into the flame, the velocity, size and entry angle of the droplets being such that they penetrate deeply into the flame but do not pass completely through it. The result is to suppress the production of smoke and to reduce the amount of heat radiated by the flames.

Description

This invention relates generally to methods and apparatus for burning liquid hydrocarbons, and more particuarly to new and improved methods and apparatus for burning the oil obtained during a test of an offshore well.

When drill stem or production tests are performed in offshore wells, many problems arise in connection with the disposal of the hydrocarbon products that are obtained. For safety reasons, it is highly undesirable to even consider the storage of these products on the drilling platform. In addition, the loading and transport of such products by tanker entails many technical problems and can be quite costly. Accordingly, on-site burning of crude oil and gases is generally considered to be the most desirable manner of disposal.

The disposal of gas by combustion does not present any great problems and can be achieved by means of a simple flare pit. On the other hand, crude oil burners must meet a certain number of requirements. First, they must be able to handle fluids containing solid particles and must be able to operate within a very wide range of flow rates, e.g., from a few cubic feet per hour to over 2,400 cubic feet per hour. Moreover, the burning process generates a considerable amount of heat and it is necessary to protect the installations of the drilling platform. A paramount consideration is to avoid polluting the ocean through the release of unburned oil drops and to avoid polluting the atmosphere through the production of smoke.

Up to the present time, burners have been used that are capable of handling oils, even those containing solid particles, at a relatively high range of flow rates while releasing practically no unburned oil drops. Such burners utilize a screen of spray water to protect the platform or rig from the back radiation of an intensely hot flame as described in U.S. Pat. No. 3,565,562. These burners, while performing in a very satisfactory manner for the most part, have one drawback. As long as the flow of oil is small (less than 350 cubic feet per hour for example), it is possible to burn away the liquid hydrocarbons without any substantial production of smoke. However, for higher flow rates, the combustion of the crude oil can product a large amount of thick smoke which is slow to dissipate and is consequently somewhat troublesome, particularly in circumstances where the drilling platform is located near to a coastline.

It is therefore an object of this invention to provide new and improved methods and apparatus for burning liquid hydrocarbons produced from a well at high flow rates by a substantially smokeless combustion process.

A further object of this invention is to provide new and improved methods and apparatus for burning away liquid hydrocarbons produced from a well in a manner that considerably reduces the thermal radiation from combustion.

These and other objects are attained in accordance with the concepts of the present invention through the practice of a method for burning liquid hydrocarbons which comprises the steps of forming an atomized spray of such liquids that burns along a flame line, and injecting sprays of water droplets into the flame in such a manner that the water penetrates deeply into the flame but does not pass completely through it. The kinetic energy of the water droplets, the opening angle of the water spray, the entry angle of the water spray into the flame and the ratio of injection water volume to volume of liquid hydrocarbons being burned away are parameters which have certain preferred values which will appear herein, with the result being almost complete suppression of the production of smoke, as well as a substantial reduction in the amount of heat radiated by the flame.

A preferred embodiment of an apparatus to carry out the method comprises an atomizer adapted to receive liquid hydrocarbons and to form a spray that is burned away around and along a flame line, and a water injection system capable of being supplied with water under pressure and equipped with a plurality of nozzles located laterally in relation to the flame line. Each nozzle, positioned so that the axis of symmetry of its spray of water converges toward the flame line at an angle preferably smaller than about 15.degree., is designed to produce water droplets having a high kinetic energy in a spray with a small opening angle, the size of the water droplets being relatively large, for example, with a diameter of the order of a millimeter. One-half of the value of the said opening-angle is preferably not greater than the angle between the axes of symmetry of the water sprays and the lines along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the spray water converges toward the flame. It has been found that this particular injection system makes it possible to obtain a clear flame void of smoke and having low thermal radiation.

For a better understanding of the invention together with further objects and advantages thereof, reference may be made to the following description and to the drawings in which:

FIG. 1 is a side view of an apparatus according to the invention;

FIG. 2 is a front view of the apparatus of FIG. 1;

FIG. 3 is a schematic view to illustrate the geometrical relationships involved in injecting sprays of water droplets into the flame;

FIG. 4 is a cross-sectional view of a water injection nozzle;

FIG. 5 is a longitudinal section of an atomizer of the apparatus of FIG. 1; and

FIGS. 6 and 7 are cross-sections taken along lines 6--6 and 7--7 in FIG. 5.

Referring initially to FIGS. 1 and 2, an apparatus in accordance with the principles of the present invention includes at least one burner assembly, and may comprise, in general, a cluster of three identical burner assemblies 10a, 10b and 10c mounted on a frame 11. The burner assembly 10a comprises an atomizer 12a, a cylindrical shroud or hearth 13a and a water injection system 14a. The burner assemblies 10b and 10c comprise the same elements bearing the same reference numbers assigned indices b and c respectively.

Each water injection system makes it possible to spray water into the flame of the sprayed oil, and tests have shown that the water injection provides very good results. The smoke is practically eliminated and the thermal radiation from the flame is considerably lowered. The theoretical explanation of the phenomenon is not well known. The elimination of smoke is probably due to a combined mechanical and chemical action of the water spray with the flame. From the mechanical standpoint, it is considered probable that the impact of drops of sprayed water with the burning oil drops breaks up the latter and thus improves the atomizing of the oil. Moreover, there is probably a chemical reaction between the water and the oil yielding much lighter combustion products. In fact, with water injection, the flame obtained is very similar to that produced by burning natural gas. From the standpoint of the reduction of thermal radiation, as the water vaporizes it absorbs a relatively large amount of heat, and the vaporized water forms a protection against infrared rays. Further, an endothermic reaction between the water and the oil lowers the temperature of the flame.

Be that as it may, tests have shown that the water injection method is particularly important. First of all, the water flow rate should be between 1 and 1.8 times the oil flow rate in volume. Without water injection, oil combustion produces a thick black smoke. On the other hand, with a water flow rate higher than 1.8 times the oil rate, a large amount of gray smoke with a water vapor base is let off. A water flow rate of the order of 1.2 times the oil rate yields in most cases a clear flame without any smoke.

The geometry and the kinetic energy of the water spray should be such that substantially all the water penetrates deeply into the flame but does not go through it. Accordingly, the water supply pressure should be sufficiently high, of the order of 300 psi for example, and a suitable type of nozzle must be used. Each spray of water must be suitably directed, must have a small opening angle and must be made up of water drops of given dimensions. The fact that the water droplets must penetrate deeply into the flame implies an appropriate drop size. Very finely sprayed water, obtained for example by means of compressed air, produces an ineffective cloud of water which is practically vaporized whereas too coarse a water spray falls like rain and entrains the oil drops with it, forming an oil slick on the water therebelow. In order for all the water to penetrate into the flame, the opening angle of the spray must be sufficiently small so that all the water converges toward the flame. It is also necessary for the angle between the axes of symmetry of the water sprays and the flame, respectively, to be sufficiently small so that the droplets do not go through the flame. During tests, optimum conditions were obtained with water sprays having an opening angle of about 15.degree., the nozzle-line forming an angle of about 7.degree.-8.degree. with the flame-line, and the nozzle sprays consisting of drops of water with a diameter of the order of a millimeter.

Referring again to FIGS. 1 and 2, the burner assemblies 10a, 10b and 10c are mounted on a frame 11 composed, for example, of a square base 15 at the corners of which are fixed two rear uprights 16 and two front uprights 17 shorter than the rear uprights 16. A front upright 17 is shown cut away in FIG. 1 to illustrate the water injection system 14a. An intermediate horizontal support is fixed to the upper end of the front uprights 17 and to an intermediate part of the rear uprights 16. This intermediate support is composed of three side members 20, 21 and 22 connected by means of three cross members 23, 24 and 25 perpendicular to the side members. The upper ends of the rear uprights 16 are connected by means of an upper cross member 26 in the middle of which is perpendicularly attached an upper side member 27 whose front end is itself attached to the cross member 25 by a central upright 28. The burner assembly 10a is attached under the intermediate support and the burner assemblies 10b and 10c over this support by means of right-angle brackets and bolts (not shown). Such a frame, of relatively small dimensions, allows easy disassembly of the upper burner assemblies 10b and 10c for transport.

Wheels 30 are mounted on the exterior of the base 15 and can move on a circular horizontal rail or track 31 attached to the end of a beam of square section and indicated generally at 32. This beam 32, which can be about 50 feet long, for example, allows the apparatus to be mounted on the side of a drilling platform beyond the outline of the platform in order to reduce heating of platform equipment. The beam 32 is of conventional construction with angle-irons and other structural members chosen in accordance with the force to be supported. The wheels 30 allow the apparatus to rotate around a vertical axis 33 for suitable positioning in relation to the direction of the wind. The rotation of the apparatus may be remote-controlled, even during production tests, by means of cables (not shown) or the like.

The atomizer 12a has a cylindrical form around a middle line 34a which forms the axis of symmetry of the flame. The atomizer 12a comprises an oil admission tube 35a arranged coaxial with this line and an air admission tube 36a arranged radially. The atomizer 12a, which will be described in greater detail below, is designed to produce a jet of sprayed oil along the middle line 34a. The cylindrical shroud 13a, open on both ends, is mounted coaxially with the atomizer 12a, the rear face of the shroud being substantially within the plane of the front face of the atomizer. The shroud is preferably made of a refractory sheet metal and is designed to stabilize the flame of the oil jet. In fact, turbulences are produced at the outlet of the atomizer and have the effect of moving back the burning oil drops which constantly ignite the oil jet near the outlet of the atomizer 12a. Also a pilot fitting 37a (FIG. 2) fixed under the atomizer may be supplied with gas in order to provide a continuous pilot flame capable of reigniting the oil jet in the event of flame extinction due, for instance, to the momentary production of incombustible fluids.

The water injection system 14a includes a tubular ring 40a mounted around the front end of the shroud 13a and equipped with a plurality of nozzles 41a regularly spaced around the ring 40a, the ring being connected to a water admission tube 43a (FIG. 1) at its lower part. As shown in FIG. 4, each nozzle 41a includes a tube 70 with a central bore 71 and threads 72 and 73 at each end. A cap 74 is screwed onto the outer end of the tube 70 and has a central orifice 75 as shown. A counterbore 76 is formed in the outer end of the tube 70, and the radial arms 77 of a flow needle 78 are trapped between the cap 74 and the end wall of the counterbore in order to fix the needle centrally within flow path through the nozzle. A nozzle constructed as shown in FIG. 4 is an example of a type of nozzle that will form a water spray having the proper opening angle of about 15.degree.. Each nozzle is symmetrical around a nozzle-line 42a that coincides with the axis of symmetry of the water spray, and the axis converges toward the flame-line 34a.

As shown in FIG. 3, the spray of atomized oil extends outwardly in front of the atomizer head 12a and burns along and about the axis of symmetry 34a in a generally cone-shaped flame, the flame front being about 1 foot ahead of the atomizer outlet. The line 38 may be considered as lying in the outer surface of the cone and therefore defining the path of travel of the outmost oil drops. In a typical example, the opening angle of the oil spray cone is about 15.degree.. The axis of symmetry 42a of the water spray, also cone-shaped, converges toward the line 34a and forms a small angle with the latter, the angle being less than about 15.degree. and preferably 7.degree. to 8.degree.. Each nozzle, supplied through the tube 43a and the ring 40a, is arranged to project a slightly flared spray of water whose axis of symmetry 42a converges toward the line 34a and whose opening angle is relatively small so that the outer water drops, that is to say those drops whose trajectory forms the smallest angle with the line 34a, converge toward the line 38. In other words, the half value of the water spray opening angle is smaller than the angle formed by the line 42a and the line 38 along which the outermost oil drops are traveling. In this way, practically all the projected water penetrates into the flame of the burning oil. By way of further example, the parts in a typical embodiment are sized such that the axes of symmetry 42a of the water sprays intersect the axis of symmetry 34a of the oil spray at a point A that is located about 11 feet in front of the front face of the atomizer head 12a. On the other hand the paths of travel of the innermost water droplets intersect the axis 34a at a point B that is located about 6.5 feet to the front of the outlet of the atomizer head 12a. In the geometrical arrangement shown in FIG. 3, the angle between the lines 38 and 42a is about 14.5.degree. which satisfies the condition that the half-value of the opening angle of the water spray be no greater than this angle. Of course it will be appreciated that the spray opening angle could be opened up somewhat to the neighborhood of 28.degree.-30.degree. and still have substantially all of the water droplets moving toward the flame.

Referring again to FIGS. 1 and 2 the oil, air and water supply of the burner assemblies 10a, 10b and 10c takes place through a multiple rotation joint 45 mounted in the beam 32 along the vertical axis 33. This rotating joint has three fixed parts 46, 47 and 48 communicating respectively with three mobile parts 50, 51 and 52 in an intercalated arrangement. A pipe 53 carrying the oil coming from the well is connected to the fixed part 46. Two other pipes 54 and 55 respectively supplying water and air under pressure are connected to the fixed parts 47 and 48 of the rotating joint. The mobile part 50 is connected via a tube 56 to a distributing joint 57 that is connected via three pipes to the respective oil admission tubes 35a, 35b, and 35c. Two of the pipes 58a and 58b can be seen in FIG. 2 and the pipe leading to the upper right hand burner assembly is not shown but may be visualized as extending upwardly and to the left of the joint 57 when viewed from the rear. The mobile part 51 is connected via a tube 60 to a distributing joint 61 that is connected to the water admission tubes 43a, 43b and 43c. The mobile part 52 is connected via a tube 63 to a distributing joint 64 that is connected to the air admission tubes 36a, 36b, and 36c of the atomizers. The water pipe 54 is equipped with a flow control valve 66 allowing water flow to be varied. This control is however not necessary if an adjustable flow pump is available.

If desired, a water spray screen may be set up between the burner assemblies and the equipment of the drilling platform. This water screen is obtained for example by means of a horizontal tube 67 fixed by suitable means on an intermediate part of the beam 32 and equipped with nozzles 68 directed in a vertical plane upward and downward. However, in general, this screen is not essential owing to the reduction in thermal radiation obtained by the injection of water into the flame. The burner assemblies 10a, 10b and 10c are mounted on the frame 11 so that their flame lines form an angle of about 10.degree., the lower flame line being substantially horizontal. Two of the flame lines, namely 34a and 34b are indicated in FIG. 1 and it will be appreciated that the flame line for the burner assembly 10c projects slightly upwardly and to the left when viewed from the rear of the assembly as shown in FIG. 2.

Referring to FIGS. 5, 6 and 7 a detailed representation of one of the atomizers, 12a for example, is given. This atomizer includes a cylindrical body 80 having a bore 81 open toward the front end and leaving toward the rear a transverse wall with an opening 82 of smaller diameter threaded on its outer part. The opening 82 is designed to receive the oil admission tube 35a. The body 80 also includes, at the rear of the bore 81, a circular recess 83 designed to receive a mechanical atomizer head 84 of cylindrical shape which leaves between its outer surface and the bore 81 an annular chamber 85. Toward the back, the mechanical atomizer head 84 has a series of inclined passages 86 which bring the opening 82 into communication with the annular chamber 85 and, toward the front, it has passages 87 bringing the annular chamber 85 into communication with a bore 90 cut coaxially in the mechanical atomizer head 84. These passages 87, tangent to the bore 90 as shown in FIG. 6, impart a rotary movement to the oil coming from the annular chamber 85 thereby creating a mechanical spraying of this oil.

A part 91 of approximately conical form bears against the mechanical atomizer head 84 and holds it in the axis of the body 80. The conical part 91 includes a central converging opening 92 and a peripheral recess 93 cut on its outer surface and designed to receive an O-ring seal 94. Downstream of the conical part 91, the body 80 includes an air inlet connection 95 having a radial passage 96 threaded at its outer end. On the front end of the body 80 is fixed, by means of screws 97, a ring 98 which, with its rear face, the bore 81 and the front face of the conical part 91, forms an annular chamber 100. A convergent-divergent opening is made at the center of the ring 98 and tangential passages 101 (FIG. 7) are made at the back of this ring between the chamber 100 and the central opening. The convergent passages 101 give the air entering through the opening 96 the form of jets impinging at a given angle on the oil leaving the opening 92. In this manner, a second atomizing effect is obtained by the impact of air jets on the oil.

In operation, the crude oil produced by a well during a production test is sent through the pipe 53 to the three atomizers 12a, 12b and 12c. Likewise, compressed air or gas produced by the well, if there is a sufficient amount of this gas, is sent via the pipe 55 to the three atomizers. Furthermore, water under pressure is sent through the pipe 54 to the water injection devices. With the pilot lights 37a, 37b and 37c previously ignited, for example by means of a conventional electrical device (not shown), the jets of sprayed oil are ignited, the flames being stabilized by the action of the envelopes or shrouds 13a, 13b and 13c. Water flow is then adjusted by means of the control 66 in order to obtain the clearest possible flame and the smallest amount of smoke. Such a device can burn about 10,000 barrels of oil per day at medium pressure of about 35 psi and up to 15,000 barrels per day if the oil pressure is high. With very small oil flow rates, it is possible to disconnect two burners and to send all the effluent into the burner assembly 10a for example.

Tests on this burner have shown that the atomizing obtained by the air is greatest at low oil flow rates, whereas at high flow rates, it is the mechanical atomizing provided by the mechanical atomizer 84 which is greatest. In fact for high rates the air or gas supply can be eliminated without changing the combustion. The two systems are thus complementary in providing suitable atomizing whatever the flow rate. Furthermore, it will be noted that the oil flow through the atomizer 12a takes place through large openings allowing the passage of relatively large solid particles. This feature is particularly valuable, as mentioned above, when handling oil coming directly from a well. Such an atomizer is thus particularly well suited to the spraying of crude oil that may contain solid particles and having a wide range of flow rates.

While a specific embodiment of the invention has been shown and described, it will be understood by those skilled in the art that certain modifications and variations, both in form and detail, can be made without departing from the basic concepts of the invention. For example, an assembly having only one atomizer and associated water injection system can be utilized for low flow rate applications or where otherwise desirable in view of a particular application. Owing to the previously described advantages and particularly to the elimination of smoke, the apparatus of the invention may be used for applications other than offshore production tests. Such a burner can be of value for burning oil coming from land wells and, in general, wherever quick disposal of liquid hydrocarbons is desired, for example when transport or storage would be dangerous.

Claims

We claim:

1. A method for burning liquid hydrocarbons produced at high flow rates from a well, comprising the steps of: forming an atomized spray of liquid hydrocarbons that burns after ignition along and about the axis of symmetry of said spray; and injecting sprays of water droplets into the flame in such a manner that the water droplets penetrate deeply into the flame but do not pass completely through it, the axis of symmetry for each water spray forming an angle of less than about 15.degree. with the axis of symmetry of the flame, the half-value of the opening angle of each water spray being no greater than the angle between the axis of symmetry of the water spray and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the spray water may converge toward the flame.

2. The method of claim 1 wherein the angle between the axis of symmetry of each water spray and the axis of symmetry of the flame is about 7.degree. to 8.degree..

3. The method of claim 2 wherein the droplets forming the water sprays have a diameter of about one millimeter.

4. The method of claim 1 wherein the ratio of water flow volume to liquid hydrocarbon flow volume is in the range of from 1 to 1.8.

5. The method of claim 4 including the further step of adjusting the amount of water flow volume to obtain substantially the clearest flame with minimum production of smoke.

6. The method of claim 4 wherein said ratio is 1.2.

7. Apparatus for use in burning away liquid hydrocarbons produced from an oil well, comprising: an atomizer having means to receive liquid hydrocarbons from the well and to form an atomized spray thereof that is burned away along and about the axis of symmetry of said spray; and a water injection system including a plurality of water spray nozzles for injecting sprays of water droplets into the flame in such a manner that the water droplets penetrate deeply into the flame but do not pass completely through it, said spray nozzles being aligned such that the axis of symmetry of each spray of water droplets forms an angle of less than about 15.degree. with the axis of symmetry of the flame, the half-value of the opening angle of each spray of water droplets being no greater than the angle between the axis of symmetry of the spray and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the water droplets may converge toward the flame.

8. The apparatus of claim 7 including means for mounting said spray nozzles in an annular array about said flame so as to project sprays of water droplets from all around the base of the flame.

9. The apparatus of claim 8 further including means for supplying water to said spray nozzles, said supplying means comprising a flow control valve for allowing adjustment of the ratio of water flow volume to liquid hydrocarbon flow volume.

10. Apparatus for use in burning away liquid hydrocarbons produced during a test of an oil well, comprising: an atomizer having means to receive liquid hydrocarbons from a well and to form an atomized spray thereof that is burned away along and about the axis of symmetry of said spray; cylindrical means surrounding said axis of symmetry and mounted coaxially thereof, said cylindrical means being adapted to improve the mixing of said atomized spray with air; and an array of water injection nozzles mounted around the downstream end of said cylindrical means and aligned to inject sprays of water droplets into the flame in such a manner that the droplets penetrate deeply into the flame but do not pass completely through it, the axis of symmetry of each spray of water droplets forming an angle of less than about 15.degree. with the axis of symmetry of the flame, the half-value of the opening angle of each spray of water droplets being no greater than the angle between the axis of symmetry of the spray of water droplets and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the water droplets converge toward the flame.

11. The apparatus of claim 10 further including an annular water supply tube arranged about the downstream end of said cylindrical means, said nozzles being carried by said tube.

12. The apparatus of claim 10 wherein said atomizer includes means to impart a rotary movement to said liquid hydrocarbons to improve the atomization thereof.

13. The apparatus of claim 12 wherein said atomizer further includes means to impinge a gaseous fluid under pressure on said hydrocarbons to further improve the atomization thereof.

14. The apparatus of claim 10 further including means for providing a generally vertically directed water screen to provide a protection against the back radiation of the burning hydrocarbons.

15. A method for burning liquid hydrocarbons produced at high flow rates from a well, comprising the steps of: forming an atomized, substantially cone-shaped spray of liquid hydrocarbons that burns upon ignition in an outwardly diverging region having an axis of symmetry; injecting a plurality of sprays of water droplets into the flame from spray locations disposed in a circular array that is concentric with, and extends completely around, said axis of symmetry and is located radially outwardly thereof, said water droplets being of sufficient size and possessing kinetic energy such that they penetrate deeply into the flame but do not pass completely through it; and controlling the rate of water flow with respect to the rate of flow of the liquid hydrocarbons to provide a ratio therebetween that is in the range of from 1 to 1.8.

16. The method of claim 15 wherein said ratio is about 1.2.

17. Apparatus for use in burning away liquid hydrocarbons produced during a test of an oil well, comprising: a plurality of atomizers arranged in a cluster and having means to receive liquid hydrocarbons from a well and to form atomized sprays that are burned away along and about the axis of symmetry of each spray; and a water injection system associated with each atomizer, each water injection system including a plurality of water spray nozzles for injecting spray of water droplets into a flame in such a manner that the droplets penetrate deeply into the flame but do not pass completely through it, said nozzles being aligned such that the axis of symmetry of a respective spray of water droplets forms an angle of less than about 15.degree. with the axis of symmetry of a flame, the half-value of the opening angle of each spray of water droplets being no greater than the angle between the axis of symmetry of the spray and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the droplets converge toward a flame.

18. The apparatus of claim 17 wherein the axis of symmetry of one flame is directed substantially horizontally and the axes of symmetry of the other flames are directed to diverge outwardly of said axis of symmetry of said one flame.

19. Apparatus for use in burning away liquid hydrocarbons produced during a test of an oil well, comprising: an atomizer having means to receive liquid hydrocarbons from a well and to form an atomized spray thereof that is burned away along and about the axis of symmetry of said spray; cylindrical means surrounding said axis of symmetry and mounted coaxially thereof, said cylindrical means being adapted to improve the mixing of said atomized spray with air; and an array of water injection nozzles mounted around the downstream end of said cylindrical means and aligned to inject sprays of water droplets into the flame in such a manner that the droplets penetrate deeply into the flame but do not pass completely through it, the axis of symmetry of each spray of water droplets forming an angle of less than about 15.degree. with the axis of symmetry of the flame, the half-value of the opening angle of each spray of water droplets being no greater than the angle between the axis of symmetry of the spray of water droplets and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the water droplets converge toward the flame, said atomizer, cylindrical means and water injection nozzles comprising an assembly that is mounted on a frame, a beam adapted for attachment to the side of a drilling platform, and means for mounting said frame and said assembly on said beam for rotation about a vertical axis.

20. The apparatus of claim 19 wherein said atomizer and said water injection nozzles are supplied via a piping system including a multiple rotatable header joint aligned with said vertical axis.

21. Apparatus for use in burning away liquid hydrocarbons produced during a test of an oil well, comprising: a plurality of atomizers arranged in a cluster and having means to receive liquid hydrocarbons from a well and to form atomized sprays that are burned away along and about the axis of symmetry of each spray; and a water injection system associated with each atomizer, each water injection system including a plurality of water spray nozzles for injecting sprays of water droplets into a flame in such a manner that the droplets penetrate deeply into the flame but do not pass completely through it, said nozzles being aligned such that the axis of symmetry of a respective spray of water droplets forms an angle of less than about 15.degree. with the axis of symmetry of a flame, the half-value of the opening angle of each spray of water droplets being no greater than the angle between the axis of symmetry of the spray and the line along which the outermost particles of burning hydrocarbons are traveling so that substantially all of the droplets converge toward a flame, the axis of symmetry of one flame being directed substantially horizontally and the axes of symmetry of other flames being directed to diverge outwardly of said axis of symmetry of said one flame.

22. The apparatus of claim 21 wherein a cylindrical shroud means is associated with each atomizer and is adapted to produce turbulence in air flow around the outlet of a respective atomizer to improve the mixing of said atomized sprays with air.

23. The apparatus of claim 22 further including an annular water supply tube arranged around the downstream end of each shroud means, the plurality of nozzles for each water injection system being attached to a respective water supply tube.