Field, of the Invention

The invention relates to a burner, in particular, the invention relates to a well effluent burner and may preferably be embodied in a rotary cup burner for the disposal of well effluent from both on-shore and off-shore oil and gas wells. The invention also comprises a manifold comprising one or more of such burners.

S¾€¾?QU nd ¾rid. .riQr art

When a flow testing, well clean-up or under balanced drilling (UBD) operation is being performed, it is normally the case that the produced well effluent is disposed of by flaring. In the flaring operation, gas is usually routed to a simple "pipe flare", but combustible liquids require atomisation before they can be burned.

The burner heads or atomising heads presently utilised fall into two categories, namely swirl atomisation heads and velocity atomisation heads. Both are dual fluid devices and burn a combination of well effluent and a propeiiant. The propeiiant is usually compressed air, although on rare occasions produced gas has been used. With regard to the swirl atomiser, this has the advantage of low air consumption but also has three disadvantages, namely that first it has high flow resistance or "back pressure", second it has a tendency to block and third it is subject to erosion caused by solids.

With regard to the velocity atomiser, this has the advantage of a relatively large bore and thus is much less likely to block. It also has a relatively tow back pressure when compared to the swirl atomiser and benefits from simplicity of construction, making it therefore also simple to maintain, This method also has three disadvantages - first, it has very high air consumption, second, it has a limited range of operation or "turndown" and third, it is vulnerable to erosion caused by solids. i addition, both types of atomiser suffer from a fixed, predetermined flame pattern, which is not conducive to maximising the entrapment of air into the effluent at a given time

The well effluent is unrefined and therefore its composition and characteristics such as viscosity, density, and surface tension are heterogeneous ···· the composition of the effluent varies considerably in the course of each operation, as does the rate at which it is emitted from its source. For example, during clean up operations, the composition will include non- combustibles such as water, solids such as formation sand, drilling mud, perforating debris, and frack returns. The existing heads are simply not fit to handle this diversity of material and as such, there is a real need for a more flexible, multi-phase effluent burner.

To the best knowledge of the inventors, all known existing well test / under balanced drilling oil burners rely on compressed air as the propeiiant to provide the energy to atomise the fluid in preparation for combustion.

The compressed air is introduced directly to the oil within the burner head. The

introduction of the air to the oil in the head presents two problems. The first problem is that if the oil pressure in the head is greater than the air pressure in the head due to very high gas to oil ratio or partial blockage or blockage at the burner outlet, then the pressure differential between the air and the oil will drive oil down the air line.

This has happened in the past resulting in containment failure from either simple

mechanical failure from overpressure. This most commonly occurs at the compressor or the air lines which travel from the compressor to the burner. The air system might, for example, have a design pressure of 150 psl approximately and the hydrocarbon system might have a design pressure of 1440 psi approximately. The air system relief valve will only be sized to accommodate the full compressor discharge flow rate, not the additional flow rate from the influx of hydrocarbons.

The second problem is that in instances where the hydrocarbons feed flows into the air system, the very rapidity of the hydrocarbon influx to the air system and the relative temperatures of both systems, have the potential to cause compression ignition to occur within the air/hydrocarbon mixture resulting in overpressure and a compression ignition explosion.

To date the industry has addressed these hazards by the installation of a check vaive in the air line. An example of the prior art is shown at. figure 12. Figure shows a well effluent burner of the prior art. indicated generally at 502. Well effluent burner 502 comprises an oil feed 504 and an air feed 506 terminating in burner head 508 in which the air and the oil supplied to the burner head 508 in use, by the oil feed 504 and the air feed 506 respectively., mix. Both the oil feed 504 and the air feed 506 comprise a check valve 510 512. The check valves S10 512 are one way valves allowing flow of oil and gas towards the burner head 508 but preventing feedback in the opposite direction, thereby preventing reverse flow.

Check valves of the type outlined In the prior art example above are normally used to prevent reverse flow and not to act as the sole or primar harrier between two pressure systems. Unfortunately because of the nature of deployment of these devices in the pipework there is a very real risk that debris from the pipework in the form of pipe scale, (or any other foreign material that may become lodged within the pipe during transport), will become dislodged and foul the check valve rendering it Inoperable. There may be no manifestation of this in the functioning of the burner so the operators will, not be aware that their safety system is compromised. The attendant problems can lead to damage to property, injury and loss of life.

Operators do and should flush the Ones as part of their operating procedure to remove loose debris, but the act of pressurization of and fluid flow in the lines upon deployment can cause previously adhered pipe scale to become dislodged and consequently foul the check valves,

It is therefore amongst the objectives of the invention to solve these and other problems.

S.umma.¾:..Qi..s;hgJoyentioo In a first broad, independent aspect, the invention comprises an effluent burner comprising a rctatable, hollow shaft with a first end for attaching to an effluent source and a second, output end., wherein the first and second ends are in fluid communication with each other; whereby effluent disposes centrifugally at said output, the burner further comprising a blast medium feed, said blast medium feed comprising an inlet for attaching to a supply of blast medium and an outlet, the inlet and outlet being in fluid communication with one another, wherein said outlet is configured to channel said centrifugally dispersed effluent,

The outlet is also configured to shatter the centrifugally dispersed effluen The routing of the effluent up the shaft is advantageous from a safety perspective because it is not out in the environment until virtually the point of ignition,

This form of burner, comprising as it does a straight or substantially straight shaft, advantageously provides minimal back pressure.

Advantageously, because there only a small distance for the blast medium and the effluent to travel in order to mix, there is also minimum erosion caused by the movement of solids across the cup or generally about the burner. This prolongs the life of the burner. The effluent burner of the invention also provides an unexpected and original solution to the problem of feedback of the hydrocarbon feed into the air system by presenting a solution whereby the air and the effluent are introduced to one another outside of the structure of the head of the burner. As such, the possibility of effluent feeding back into the air feed is completely removed, completely eradicating this possibility as a cause of containment failure or compression ignition explosion.

A consequence of this is that the check valves may be removed from the air and effluent feeds, which simplifies and increases the structural integrity of those feeds.

Preferably said outlet is formed in the gap between the output end of said shaft and a stationary shroud.

The provision of a gap defined in this way minimises the number of separate parts required and as such bolsters the durability and structural integrity of the burner. This optimises atomisation and entrapment of the atomised effluent in the blast medium.

Further, it is not necessary for the shroud to spin either in tandem with or separately to the shaft in order for blast medium to be introduced to the effluent. A burner with a stationary shroud is therefore more energy efficient.

Preferably, the outlet and the output are positioned substantially adjacent each other such that in use, when effluent is fed through the shaft and out of the output end and blast medium is fed through the feed and out of the outlet, the effluent and blast medium emerging from respectively the output end and the outlet are introduced to one another Immediately,

Preferably the burner comprises at least one controller wherein at least one of the rate of flow of the blast medium and the speed of rotation of the shaft is controllable by the controller.

The separately controllable rates of rotation and feeding of blast medium allow for greater turndown. Such controls allow also for flame pattern and flame shape to be varied.

Further outputs can be refined in order that secondary air entrapment is maximised for facilitating combustion and for minimising heat radiation,

Preferably, the output end of the shaft and the outlet of the blast medium feed terminate on substantially the same plane.

This configuration ensures that the distance effluent has to travel before mixing is rationalised.

Preferably, the outlet of the blast medium feed comprises an annular gap surrounding the shaft The annular gap provides a means of maximising the exposure of effluent to blast medium, by providing blast medium ail the way around the output.

Preferably, the shaft is rotated via a wheel, and wherein the wheel is attached to and is arranged co-axially around the shaft.

Preferably, the burner further comprises at least one drive nozzle, wherein the nozzle is oriented relative to the wheel such that fluid emitted from the nozzle turns the wheel

The wheel and in particular the turgo wheel provides a rotation means wherein the shaft can be rotated without recourse to its being contacted by a solid object - it can be propelled by fluid emitted from the drive nozzles. This saves on wear of the parts through friction.

Preferably, there are four nozzles and the nozzles are arranged relative to the wheel such that they comprise four corners of a notional square.

The formation of the nozzles is such to provide an optimal balance of drive and

controllability since it creates the possibility that the nozzles can be independently controlled. Preferably, the outlet comprises a flared cup, said cup comprising an inner, pre-filming surface and wherein the effluent enters the cup through an aperture in the cup.

The provision of the cup provides an elongate surface along which the effluent travels and spreads, before introduction to the blast medium.

Preferably, in use, the cup rotates.

The centrifugal action of the cup is particularly effective in separating high water cut well effluent into its components, concentrating combustibles in the core of the spray and thereby allowing stable combustion of higher water-cut well fluids. This is particularly advantageous when employed in conjunction with clean up operations and multi-phase metering.

Preferably, a spacer is provided between the output end of a shaft and a stationary shroud, whereby the blast medium outlet is spaced radially from said output end.

The spacer advantageously provides an allowance of space for the effluent to spread.

Preferably, the invention further comprises a vane inside the bore of the shaft.

The vane provides progressive spin to the fluid independent of wall friction or the internal shear of the fluid. This allows the effluent in the shaft to be gradually spun up the shaft.

The invention may also comprise an effluent burner substantially as described herein and as illustrated by any appropriate combination of the text and/or drawings. n a second broad, independent aspect, the invention comprises a manifold, comprising one or more effluent burners according to any of the preceding claims, each of said burners comprising an outlet shaft and wherein the orientation of each of the outlet shafts of the burners is horizontal or offset from the horizontal The provision of multiple burners in this manner serves to burn effluent more completely and effectively because effluent expelled from the upper burners in the manifold or array will pass through a plurality of ignited streams, thus having more opportunities to bum than if only a single burner were present

The orientation of the burners in this manner means that effluent which is not burnt is nonetheless propelled away from the burner and as such does not drop back onto the burner.

The invention may also comprise a manifold substantially as described herein, with reference to and as illustrated by any combination of the text and/or drawings.

The Invention will now be described with reference to the drawings of which;

Figure 1 is a cross-sectional side view of a burner of the invention,

Figure 2 is a side view of a burner of the invention,

Figure 3 is a side view of a burner of the invention,

Figure 4 is a side view of a burner of the invention showing the outlet end,

Figure 5 is a side view of a burner of the invention showing the inlet end,

Figure 6 is an axial cross-sectional view of the drive mechanism of the invention,

Figure 7 is a cross-sectional side view of a burner of the invention,

Figure 8 is a side view of a manifold of the invention at a first angle of orientation,

Figure 9 is a side view of a manifold of the invention at a second angle of orientation. Figure 10 is a side view of a further outlet of the invention, and Figure 11 is a side view of a still further outlet of the invention. s Figure 1 is a perspective side view of a prior art burner, OitalMDesCTgtim

At Figure 1 is shown a burner 2. The burner 2 comprises a shaft 4. The shaft 4 is hollow0 and comprises an internal bore 6, as well as a first inlet end 8 and a second outlet end 0, The burner 2 is made of mixed materials, being predominantly a mixture of metals alloys and plastics materials. The shaft 4 is made of a metal or alloy, The shaft 4 may have walls of a variety of different thicknesses; likewise, the diameter of the Internal bore 6 of the shaft 4 may vary. The shaft 4 is advantageously circular cylindrical - this aids its rotation5 relative to other parts of the burner 2 and facilitates fluid-proof sealing of the shaft 4 relative to other parts of the burner 2.

At the inlet end 8, the shaft 4 meets inlet assembly 12, Inlet assembly 12 comprises effluent inlet 14 which is sealingly attached to shaft 4 via a first seal 16. In use, effluentQ inlet 14 is static and shaft 4 rotates. The interface between rotating shaft 4 and static effluent inlet 14 is via rotating shaft bearing 18, First seal 16 ensures that effluent passing across the join between shaft 4 and effluent inlet 14 does not escape, or otherwise affect the working of the burner 2. Towards the outlet end 10 there is likewise an interface between static blast shroud 20 and rotating shaft 4; this is governed by second shaft5 bearing 22 and second seal 24. Both shaft bearings 18, 22 and both seals IS, 24 are

restrained and held in place by housing 26, which rear housing 28 restraining first seal 16 and first shaft bearing 18 and with forward housing 30 restraining second shaft bearing 22 and second seal 24. Both of seals 16 _t 24 are lip seals. A wheel 32, advantageously a Turgo wheel, is attached to shaft 4. The wheel 32 is mounted coaxially around the shaft 4. The wheel 32 is housed in housing 26, In this embodiment, the wheel 32 comprises a plurality of arms 34 with each arm 34 terminating in a cup 36. Rear housing 28 Incorporates apertures 38 through which are fed drive ports 40. The drive ports 40 are tubular and terminate with tapered head 42. The drive ports 40 are orientated such that drive medium passed through the said ports 40 ll be expelled onto the cups 36 causing the wheel 32 and thus also the shaft 4 to rotate. The drive ports 40 and the cups 36 are advantageously angled relative to each other such that the drive medium expelled will rotate the wheel 32 with maximum efficiency, In this preferred embodiment the ports 40 are angled at approximately 20° from the vertical The drive medium may be any of air, water and steam, although other media may be found to be appropriate. Drive medium exhausts 44 are present in both rear housing 28 and forward housing 30 for exhausting the drive medium after use. The exhausts 44 are positioned to aid the cooling of the respective bearings and seals to which they are adjacently located. The housing 26 allows the location of fixing of the drive nozzles 40. The wheel 32 and nozzles 42 are encased in the housing 26 in order that drive media may otherwise be contained. There are four drive ports 40 in this embodiment, but there may be a varying number, depending of the required torque. The burner 2 thereby uses a flow of air via the wheel to mechanically impart its energy to the oil without contact with the oil. Once used in this way, the spent air is exhausted through the exhausts 44 to the atmosphere. As such, it does not contact or mix with the oil.

The blast shroud 20 is attached to the forward housing 30. The blast shroud 20 comprises a blast medium inlet 46. The blast medium inlet 46 leads to a channel 48 which terminates at exit 50 which in preferred embodiments forms an annular gap around outlet end 10 such that it surrounds and is coterminous with outlet end 10. In particularly preferred embodiments, the cup as well as the shaft are surrounded. The blast medium inlet 46 is perpendicular or substantially perpendicular to the channel 48.

In this embodiment outlet end 10 comprises a rotating cup 52. The rotating cup 52 provides a pre-filming surface for effluent expelled from the outlet end 10 of the shaft 4 which is adjoined to the bottom of the cup 52. The outlet end 10 comprises an aperture in the bottom of the cup 52. The cup 52 is positioned concentrically within the blast shroud 20 defining the annular gap or exit 50 from which the blast medium is expelled. Like the drive fluid may be any of air, steam and water and the blast medium may be either air or steam. In use, effluent spreads out across the pre-filming surface 54 of the cup 52 before meeting the blast medium being propelled through the outlet 50. The blast medium and the effluent immediately come into contact with each other. The air shatters the liquid film into droplets. This air is entrained in the subsequent spray mixture by motion of the mixing itself and this aids the subsequent ignition of the mixture. Figures 10 and 11 show alternative embodiments of outlet end 10. At figure 10, there is shown outlet end terminating in plate 60. Plate 60 is perpendicularly disposed to the passage of bore 8 through the shaft. The plate 60 may in some embodiments be static and 5 may in other embodiments be spinning. At figure 10, there is a space 62, instead of a plate or cup; although the cup 62 of figure 1 is the preferred item, any of the items listed worked advantageously as a spacer between outlet 10 and the annular gap SO.

The hollow shaft 4 incorporates an axial vane 56. The axial vane 56 comprises a tapered w V-shaped notch 58 on the inside bore 6 of the shaft 4; fluid passing via the vane 56 is imbued with an additional positive rotation or spin as it travels up the internal bore 6 of the shaft 4. The vane 56 sen es to progressively impart spin to the fluid such that it has less internal shear.

15 Figures 8 and 9 show a manifoid 100 comprising a plurality of burners 2, The burners 2 are designed to comprise such a manifold 100 wherein the shafts 4 and outlet ends 10 of said shafts 4 are orientated away from the vertical - most likely horizontal or within a range of less than 45° to the horizontal - offset substantially from the vertical axis. Thus, the manifold 100 may be arranged such that it points over the side of a drilling platform or the 0 like. Multiple burners may be in other combinations, such as triangular or four square but vertical inline is preferred. In any configuration, the spray pattern of the constituent burners 4 would be adjusted to prevent spray / spray interference and droplet collision.

Advantageously arrays of this sort drop material which is more difficult to ignite from one5 flame to another. Thus the more difficult to ignite material has several opportunities to burn because it is passing through more than one flame in all but the bottom case.

The angle of each of the tapered nozzles 42 is adjustable relative to the housing 28. Q The various components of the burner 2 are bolted together but other means of

attachment such as adhesive or the shaping of said components such that they form a frictional fit together may be deemed appropriate. At Figure 4 the burner is shown to have a cuboidai housing 26 and a blast shroud 20 and a cup 52 arranged concentrically around shaft 4, The annular gap/exit 50 is clearly shown in this embodiment as is the arrangement of drive nozzles 40.

Figure β in particular shows the orientation of the cups 36 which this embodiment are directly attached to the wheel 32, i.e. there are no interceding arms. Also in this embodiment there is shown a plurality of drive medium exhaust ports 40 grouped together. in use, effluent enters the effluent inlet 14 and subsequently the inlet end 8 of the shaft 4, which in preferred embodiments is driven to rotate via propulsion of the wheel 32, Upon entering the internal bore 6 of the rotating shaft 4, spin is progressively induced to the fluid as it travels axially along the shaft. The spin is emphasised in embodiments where the shaft 4 bears an axial vane 56. The centrifugal force acting on the fluid will cause some separation of immiscible elements in the fluid concentrating the higher densities, solids, water, etc. to the shaft and cup wall.

In preferred embodiments, the fluid exits the shaft 4 and enters the cup 52 which in particularly preferred embodiments will also be rotating, Centrifugal force causes the fluid to progress along the pre-filming surface 54 to the rim 62 of the cup 52, !t leaves the cup rim 62 as a thin film disc perpendicular to the shaft 4 and cup 52 axis. This thin film disc of fluid is then shattered into droplets by the blast medium axialiy exiting the annular gap 44. The blast not only shatters the film but also reshapes the spray to the desired spray pattern. The spray shape / flame pattern and quality along with the droplet size can be modified while in use by varying the rate of flow, speed of rotation of the shaft 4 and cup 52 and pressure in the blast shroud 20. The flame pattern can also be adjusted by varying the feed rate and/or the composition of the blast medium Likewise, increasing the air pressure thins the cone of the flame. Subsequent to expulsion, the mixture is ignited by an external igniter. Preferably, the effluent burner also comprises at least one controller (not shown} wherein at least one of the rate of flow of the blast medium and the speed of rotation of the shaft is controllable by the controller. Thus, the blast medium, which in most instances will be air, performs two functions, namely the completion of the atomization process and the cont olling of the flame geometry. Confidential research and testing pertaining to this burner has led to the understanding that it has specific advantageous not mentioned in our previous patent specification which are most desirable and advantageous relative to prior art burner heads.

Tests conducted on preferred embodiments have delivered a further, unexpected advantage, namely that there is a transition from thin-film atornisation to velocity atornisation at elevated blast air shroud pressure/velocity. This is very advantageous in that it provides an intrinsic back-up system in the event of rotary failure. Thus, were the rotation of the shaft 4 to be hampered at all, the burner 2 could be instantaneously switched to velocity atornisation thereby ensuring continuous burning.