US20060084022A1

US20060084022A1 - Tornadic fuel processor

Info

Publication number: US20060084022A1
Application number: US11/244,430
Authority: US
Inventors: Uli Kruger
Original assignee: DH3 Pty Ltd
Current assignee: DH3 Pty Ltd
Priority date: 2000-09-06
Filing date: 2005-10-05
Publication date: 2006-04-20
Also published as: WO2002021045A1; US20040038164A1; AUPQ993400A0

Abstract

A method of effecting burning is described wherein combustible materials are introduced into a vortex having a high pressure periphery and a lower pressure center, or are caused to form such a vortex and there is provided further fluid to provide for the combustion of this material, and the mixture is ignited whilst in the vortex. A variation of this is method of effecting burning which includes the step of introducing as a burnable mixture, a mixture into a vortex of a type having an outer periphery with a higher pressure than its pressure at a center of the vortex. The methods are useful for generating heat, steam or disposal of wastes.

Description

FIELD OF THE INVENTION

This invention relates to a method of burning that could be used, in the generation of heat, in the generation of steam and power, and in the processing of wastes, such as toxic organic compounds.

BACKGROUND OF THE INVENTION

This invention results from discoveries related to investigations into vortexes having a low-pressure central region and a higher-pressure periphery. Such vortexes are sometimes referred to as natural or centripetal vortexes.
There are also other types of vortexes. There are vortexes with a high-pressure control region and a low pressure periphery. This invention does not relate to this type of vortex. That type of vortex may be referred to as centrifugal vortex.
Unfortunately there is confusion in the literature as to the proper name types of vortexes. It is not helped by the recognition sometime ago in some countries that ‘centrifugal’ force or acceleration is a misnomer, with the force or acceleration being more properly called centripetal. It is common to find incorrect references in old textbooks to centrifugal forces, and that expression is commonly used today by laypersons.
To clarify the matter the centripetal direction is toward the inside of a circle or column, whilst the centrifugal direction is toward the outside of the circle or column.
It is know to impart a swirling motion to air to assist in the mixing of fluids and combustion of fluids. A number of patents on the matter are for devices for internal-combustion engines. In a typical arrangement there is a pipe or casing with baffles therein. When air is passed through the pipe the baffles are used to impart a spinning, spiraling or swirling motion to the air or other fluid. See for example U.S. Pat. No. 1,684,480 (Evans).
An improvement of these arrangements involves swirling the air or fluid to a sufficient extent so to form a vortex. A vortex has a column of fluid moving in a swirling motion. The motion is structured so that a funnel shaped vortex is formed. The vortex may be formed by the application of centripetal forces to a fluid such as air or water. The centripetal forces may be formed or directed by fluid movement. At the bottom of the funnel the centripetal forces are the stronger than higher up the funnel. Accordingly the walls of the vortex are steepest at the base.
The structured turbulent flow of a vortex may be used to mix two or more fluids together or accelerate the evaporation of a fuel. Examples of patents using vortexes for this purpose includes U.S. Pat. No. 5,472,645 and 5,672,187, both by Cyclone Technologies Inc. A detailed treatise on vortexes can be found in U.S. Pat. No. 4,318,386 (Automotive Engines Associates). Typically these documents involve the use of bulky and complicated arrangements to mix fuel with air and subsequent feeding of the mixture into the intake manifold of a motor vehicle engine.
In such environments the vortex is being used to evaporate fuel and promote homogeneous mixing of the fuel with air. This can provide advantages in respect of the operation of the engine in that the engine may be run lean (high air to fuel ratio). This can significantly reduce pollutants such as NOx formation and non-burnt hydrocarbons, and improve the efficiency of the engine in respect of fuel use for a given energy output.
Of course a combustion engine is a complicated piece of machinery, designed to convert a stored chemical engine into mechanical motion by the expansion of a gas. The generation of heat is not the goal of an internal combustion engine, in fact engines include a number devices to reduce or control heat as it can detract from engine performance. An engine operates in a batch method wherein a particular mix is fired and exhausted. It also includes many components including feedback circuits, pre heating systems, and cooling systems.
A heater unit is quite different in operation to a motor vehicle engine, in that it should be capable of operating in a continuous manner. Furthermore many of the earlier patents documents do not indicate the type of vortex used, so that a reader can only speculate as to its nature.

OBJECT OF THE INVENTION

It is the object of the present invention to provide a burner for the production

BRIEF SUMMARY OF THE INVENTION

Broadly stated in one form the invention is a method of effecting burning of combustible materials which method includes the steps of causing the combustible materials to be entrained as a vortex which is of a type having a higher pressure periphery and a lower pressure center, then effecting passage of such a vortex through a downstream passageway where the vortex is caused lo enter into a chamber which has a larger cross-sectional area and is then caused to enter thereafter a passageway that is again smaller than the said larger cross sectional area, and then effecting ignition of the combustible materials the forgoing all being arranged such that any ongoing burning is constrained to be only within the chamber.
The effect of this is found to be that very high temperatures can be achieved at a center of the vortex within the chamber but very low temperatures are maintained on the sides of the chamber.
This phenomenon in trials produces temperatures at least in the range of 1300-1400 degrees Centigrade at its center so that it is able then to be used to treat materials which at this temperature will be disassociated and rendered in the case of pathogens or pollutants at least different for subsequent disposal.
Two other characteristics of this phenomenon are significant, a first being that there seems to be an action occurring within the burning that has somewhat less pollutants result as a result of the burning of a carbon based combustible material and air as typical. The specifics are later given but the unburnt hydrocarbons, the Nox's. and the CO's are significantly less than would normally be expected from a conventional burning process.
We have some possible theories about why this should be the case but at this stage have observed the phenomenon and have found these enormously valuable results.
The second characteristic is that while there can be this very high temperature at its center, the temperature at the side of the chamber confining the burning is very low to the extent that the chamber wall itself that is used to confine the burning fluids is in trials conducted so far only at most warm. The material used for the chamber therefore does not need to be and it is pointless to have materials that can withstand high temperatures. An aluminium housing for instance is used as an example and during trials is able to be touched and is simply warm to the hand.
This then means that the physical environment within the burning area is such that it is not as a result of random mixing of the combustible elements because this would not then allow for this continuing restraint of the extremely high temperatures within a cocoon. In appearance the burning area within the chamber has its luminous parts appear to be of donut shape with the donut shape being axially central within the chamber area and there is in trial instances a resonance that seems to emanate from the cocoon providing a relatively low frequency audible sound. This frequency can be altered in steps by varying pressures of supply of the combustible fluids. This establishes we think, that the directions and pressures of the combustible fluids are precise and not random.
As a result of this effect being discovered it is appreciated that each of the characteristics can be advantageously useful. The fact that the very high temperature is attained and maintained means that there will be efficient and complete combustion. This then means that it is a way of getting good efficient burning. However because the temperature is confined within the chamber the he. product fairly much in total of the burning can then be taken and used simply for heat exchange downstream or where ever.
Because the temperature is confined within the burning fluids then, the equipment for creating and holding the burning fluids can be very economical indeed and more over very low in maintenance requirements because it is not exposed to the high temperatures as such. Further, its value for pollutant disposal is again huge because of the self containment effect with very high temperatures.
The invention can be said to be also residing in a method of burning wherein combustible materials are introduced into a vortex having a high pressure periphery and a lower pressure center, or are caused to form such a vortex and there is provided further fluid to provide for the combustion of this material, and the mixture is ignited whilst in the vortex.
The invention also resides in an apparatus for burning of combustible fluids where the apparatus includes means to effect a vortex of a type where the inner part of the vortex has a higher pressure than the outer side of the vortex, and where there is a burning chamber with an inlet to receive combustible fluids with an imparted vortex and an outlet from the burning chamber such that the burning is confined to be only within the chamber.
Another form of the invention is a continuous burner capable of providing for the above method of burning.

BRIEF DESCRIPTION OF THE FIGURES

For a better understanding of this invention it will be described in relation to preferred embodiments which will be described with the assistance of drawings wherein:
FIG. 1 is a cross-sectional view of an assembly according to a first embodiment illustrating a vortex forming tube, a burning chamber, and then an outlet conduit arranged to pass through a heat transfer medium such as water prevention exhaust to air;
FIG. 2 is a five cutaway perspective view of the burner portion as shown in FIG. 1;
FIG. 3 is a cross-sectional view along the line 3-3 in FIG. 4;
FIG. 4 is a perspective view of a tube providing inlet apertures arranged in a spiral pattern and shaped so as to be capable of causing gas-passing therethrough to form within it into a centripetal vortex;
FIG. 5 is a perspective view along the same lines as in FIG. 2 except in this case, there is a continuous slot in the burner tube to provide a further way of causing inlet gases to form into a centripetal vortex;
FIG. 6 illustrates a further arrangement of a burner tube in this case having tubes around a common diameter that also is found to cause a natural or centripetal vortex within the tube; and
FIG. 7 is a perspective view of a portion of the exhaust coil used in connection with the burner.

DETAILED DESCRIPTION OF THE INVENTION

It was found that by introducing a combustible matter for instance propane gas into a chamber together with a supply of air, in such a way as to cause this combustible matter form a vortex, when the mixture is ignited a flame is formed which is visually located about a center of such a vortex and such a flame appears to be localized within generally a center of the upstream portion of the vortex.
Further, on tests conducted so far, for instance using propane gas and air where these are introduced at a controlled relative rate one with respect to the other into a chamber which is substantially closed except for a downstream outlet that a temperature within the vicinity of 1400° C. is detected within a center of the flame but that such a temperature does not extend to side wall of a chamber confining the centripetal vortex.
However, the downstream combusted gases maintaining to a large extent a residual centripetal vortex action carry with it the heat resulting from the combustion process where it can then be transferred to the walls of a passageway and transmitted to any other medium thereby.
Of significant interest in relation to this burning process is the fact that the combustion products in experiments conducted so far have reduced levels of gases that might normally be expected from a normal burning of propane.
For instance, in one instance, we have been unable to detect any significant carbon monoxides or unburnt hydrocarbons or nitrogen oxides.
Various experiments have been conducted so far to ascertain the extent to which this effect depends upon input materials, the shape and size of apertures leading into the vortex forming chamber, and the balance of gases including combustible gases, such as hydrogen and oxidizing gases, such as oxygen that might provide a best result. Of course it is envisaged that the combustible materials need not be gaseous and as such could include liquid fuel or even solid fuel such as coal dust.
The burner has a shape wherein a chamber which has a larger cross sectional area with a downstream outlet passageway with a restricted cross sectional area so as to effect some back pressure against exiting gases. This then has the result that the burning materials are confined to the chamber provided that the pressures, relative cross sectional areas and outlet size is appropriate and this has to be found by trial in any example. We have set out what is to be looked for and we have given a set of criteria that has worked for us and provides this significant advantage.
The burner also has at least one inlet aperture which is directed substantially at a right angle to a central axis of an inner cylindrical shape of the chamber in which one end is closed and the other end opens into a combustion area and where an inlet aperture is directed so it is other than directly aligned to intersect the said central axis.
By introducing air in such an arrangement through the inlet aperture, by selection of pressures of inlet fluids, including a selective relative pressure between respective fluids, there can be effected the required vortex.
The introduced mixture including a combustible material together with an oxidizer needs to be ignited as a first step. Simply locating a flame at an outlet downstream of the vortex-forming chamber can ignite the mixture.
This can be achieved by simply exposing this downstream mixture to a lighted flame, there is a flame front that travels back to close to the inlet location of the fluids being introduced into the chamber and it then forms a doughnut shaped flame. The burner may have a closable exhaust port or outlet to permit this operation. Alternatively the burner may have an electronic or other ignition means incorporated into tho housing of the burner.
In preference, the design of the burner is such that a downstream outlet has a cross-section that changes from a first cross-sectional area to a second somewhat larger cross-sectional area over a relatively short distance and thereafter defines a larger chamber hating itself a further outlet downstream.
The effect of this is found in practice to provide a limit to tho extent to which the burning names extends and downstream direction.
In preference, a portion of the chamber projects into the chamber and is such that it will be heated by and transmit heat of the flame by conducting to an inlet location.
In preference, incoming gases are subjected to a first heating by being directed past a preliminary heated member before being directed into the chamber through means to effect a vortex having a low pressure center relative to a higher pressure periphery.
It is found that in this way, the gases cm be raised to very high temperatures indeed and combining this with the nature of the process occurring within the vortex, means that there is both very high vacuum, re-circulation of the mixture and very high temperatures within the vortex.
Temperatures as high as 1400° C. have been ascertained to exist within the vortex burning cone but by reason of the nature of the vortex, the temperature at the outer edges of the vortex are very much lower so that the sides of any confining chamber ran be kept relatively low in temperature.
It is envisaged that such a burner could be used for the purpose of continuous heat creation, such as to heat a surrounding jacket of water or air. Such a device could be used for industrial or domestic purposes for use in general healing.
The burner may be used in a continuous feed waste disposal process. Provided the waste can be combusted and incorporated into a vortex then there may be very real advantages in using the vortex burner. The flux within the burner permits high temperatures to be achieved at the core of the combustion chamber. Certain toxic compounds, particularly hydrocarbon compounds, such as benzene when subjected to those conditions will be burnt or converted into a less dangerous product.
It is envisaged that waste would be fed into an established burning vortex via feeder ports. The temperature of combustion could be selected by using appropriate fuels, in some instances the waste itself may provide the fuel for the combustion process.
Advantageously for waste disposal, the vortex burner is very efficient in the mixing and combustion process. Accordingly it is envisaged that very little, if any, unburnt waste would pass through the device.
Another possible use is in the direct creation of steam. In a typical power generator, there are a number of separated systems used to produce the steam. The combustion chamber heats pipes containing a first heat transfer medium that then connects pipes containing water. The water is turned into stream and is used to turn turbines.
In contrast it is envisaged at the vortex burner could be used to directly heat water and form steam. Water could be introduced into a burning vortex of fuel. The water would vaporize and exit the device as steam. Unlike a typical combustion zone, as the vortex burner burns very clean it is expected that the directly formed steam could be safe to use for work. As the NOx output from the burner is very low, then the steam should not be unduly acidic or corrosive.
It is expected that the water would have a cooling effect on the output of the burner, but this should be manageable. It could be simply controlled by changing the amount of water or fuel delivered to the burner
It is also thought that the method could be used in respect of hydrocarbon based fuel reformation. Such methods generally involve exposing a hydrocarbon fuel and water vapor mixture to a minimum amount of heat or a plasma arc, and a suitable catalyst. During the endothermic process methane, hydrogen and carbon monoxide are produced.
An advantage of the system is that these fuel gases yield higher energy content on combustion than the original feed stock. They also provide a higher flame propagation speed and produce much lower amounts of polluting emissions.
The burner method should be suitable for use as part of a reformation system. It can be configured to introduce more than one liquid or gas, or combination thereof, into an air stream. A preliminary heating chamber could effect the hydrocarbon reformation step, with a subsequent burning of the fuel gas mixture.

PREFERRED EMBODIMENTS—EXAMPLES

Referring now to the first embodiment as illustrated in FIGS. 1, 2, 3 and 4, the vortex forming tube 1 forms a closed chamber 2 having an outlet at 3 which enters into a large portion 4 which itself then has an outlet at 5 which variously passes through outlet 6 or when the valve 7 is closed, through conduit 8.
In use propane may be passed though the bottom inlet whilst air is passes through the side inlet. The passageways are preferably separated so that the positive pressure of the propane gas does not adversely affect the ingress of air.
The vortex forming tube at its upstream end at portion 9 having a double ended cone shape.
An inner cone at 10 is positioned so as to be at a center of any flame forming and burning within a centripetal vortex being formed and as such to heat.
The material of which this portion 10 is made is 316-grade stainless steel.
Any heat will transmit by reason of conduction to the opposite end at 11.
This is arranged to be within the path of incoming gases in the passageway at 12 so that such incoming gases will strike this cone shape 11 passing over the surface and thereby gathering heat and then passing through the respective apertures such as at 13.
In this case, the size of the vortex tube, and the respective position of the various apertures can be defined in the following details, vortex tube diameter 19.01 mm, vortex tube wall thickness 1.2 mm, length 30 mm, the alignment of the inlet holds of which there are eight, is such that they are lined up in a double helix with a diameter of each inlet hold being 2.3 mm.
Inlet pressure of propane is 7 Kpa and air inlet pressure is 9-13 Kpa. The shape of these holes is more specifically shown in FIG. 3.
With a tube diameter, having an internal diameter of 16.6 mm, means that with these specifications the stoichiometric mixture of air and propane will form in the vortex tube 1 and the gas will then exit through the outlet end that is turned downstream while maintaining this centripetal vortex.
It has been found beneficial to have a direct access to the enlarged chamber 4 for affecting a lighting of the stoichiometric mixture and this is achieved by having a valve 7 that opens access through to this area temporarily at initially lighting stage.
Once lit, the valve 7 is closed and any resulting burnt and heated gases will then proceed through the full heat exchange arrangement including the coil of tube 8. Of course it is expected that in an commercial product this feature may be omitted and replaced with an electronic ignition system, located close to or in the enlarged chamber 4.
The surprising discovery is the results arising from such a process.
Firstly, it is found that there is a very high temperature indeed formed within an inverted cone shaped flame generally within the vortex tube which is kept in this location by the fact that the enlarged area 4 alters the nature of the process through the downstream path.
Because a centripetal vortex creates very unusually strong digress of vacuum and recirculation of gases and as well retention of its spiralling shape over a longer pathway, this changes characteristics of burning fat have not previously been known to exist.
A first of these is that for a reason that is not entirely understood as perhaps is the case with a number of the resulting characteristics, there is a very high temperature resulting on the inside of the vortex tube. This may be related to the lower pressure at the center of the vortex.
With a two parts of air to one part of propane, and with preliminary heating, the temperature of the gases then reaches well in excess of 500° C. where above, thermocatalytic cracking of a hydrocarbon fuel by way of an endothermic reaction process can exist.
Such a thermocatalytic cracking is enhanced by exposure at the time that the gases are exposed to very high temperatures where the exposure to specific material can be such as nickel containing alloys, aluminium oxide, or other known catalytic materials which can be either separately located in the vicinity or be incorporated within the material of a cone or tube.
Where the gases are subjected to such very high temperatures prior to entering into the vortex tube itself, then by reason of such thermocatalytic cracking, there can now be gases divided into components such as carbon dioxide, carbon monoxide, carbon, water and hydrogen.
As well of course there can be remaining elements of air, and propane.
These compounds can now enter the vortex tube so as to form into the centripetal vortex where combustion is taking place. In experiments as described, the flames assume the shape of the vortex itself with combustion progressing from the outside of the vortex, where a higher pressure prevails in a direction roughly perpendicular to the vertical center axis toward to extreme low pressure zone in the center.
Surprisingly, it appears that gases caught within the centripetal vortex will pass from the high pressure zone to the low pressure zone and back so that probably those more oxidized will then continue downstream to any exhaust heat exchanger conduit.
The results in the described test on trials so far have indicated that there is no hydrocarbon output in any exhaust, 0.03% carbon monoxide, 10.4% in carbon dioxide, 5.4% in oxygen and no nitrogen oxide.
Further, with water that is received at exhaust, the acidity or alkalinity of this is zero, in other words it has a pH of 7 strongly suggesting that it has not any dissolved nitrogen oxides.
It is suspected that the reason that no nitrogen oxide is present is that with the preliminary cracking effecting the availability of hydrogen or carbon monoxide, such materials have a greater oxidation affinity when the flame burning is excluded from being open to the atmosphere.
Referring to the second embodiment as shown in FIG. 5 now, there is shown a single slot 20 which is cut to direct in a peripheral tangential manner air passing into this into the vortex tube 21 and again there is a double ended cone 22 and 23 adapted to transfer heat from within the vortex tube to an outlet location at 22 over which incoming gases can pass and therefore be subjected to very high temperatures with the material being selected to be of a thermocatalytic creating character.
However, it is found that such a slot can also be used then to cause a centripetal vortex with all of the other characteristics described in relation to embodiment 1.
In the third embodiment shown in FIG. 6, the same characteristics exist except in this case, there are inlet apertures at 30 aligned around a common diameter of the vortex tube 31 which again has an outlet as described in FIG. 1 so that the flame is limited by reason of the substantially expanding chamber formation and the downstream gases can then be directed as desirable.
This then describes a method of burning which has been found to provide potential for enormously advantageous results including substantial reduction of polluting chemicals as a result of the combustion process, the ability to achieve very high temperatures within a confined area without having to have highly resistant heat insulating materials to contain such high temperatures, the ability to insert other materials into the flame so as to affect the destruction of these within an effective burning and high temperature with light plasma characteristics so that pollutant chemicals may be introduced and have these substantially destroyed in a reasonably effective way.
The invention can apply then to the method of effecting burning which includes the steps of introducing a burnable mixture into a centripetal vortex.
In another form, the invention can reside in apparatus having a vortex-forming chamber having apertures directed into this to effect a centripetal vortex and means to effect a lighting of this so that a burning effect will take place of the gases being input.
In a further aspect, the invention can be said to reside in the arrangement of having a heat transfer element transferring some of the heat from the burning gases to an inlet location so with the presence of an appropriate catalyst, some thermocatalytric reaction will take place prior to introduction of the gases into the centripetal vortex.
These and other embodiments are all understood to come within the concept of this invention.
Throughout this specification purpose has been to illustrate the invention and not to limit this.

Claims

1. A method of effecting burning of combustible materials comprising the steps of:

causing the combustible materials to be entrained as a vortex which is of a type having a higher pressure periphery and a lower pressure center;

then effecting passage of such a vortex through a downstream passageway where the vortex is caused to enter into a chamber which has a larger cross-sectional area and is then caused to enter thereafter a passageway that is smaller than the chamber of larger cross sectional area; and

effecting ignition of the combustible materials, the forgoing all being arranged such that any ongoing burning is constrained to be only within the chamber.

2. The method of effecting burning as in claim 1 wherein the forgoing steps are also all arranged that the outer temperature of outermost sides of the vortex burning in the chamber is approximately ambient.

3. The method of effecting burning as in claim 1 which includes the step of introducing a burnable mixture, into a vortex of a type having an outer periphery with a higher pressure than its pressure at a center of the vortex.

4. The method of effecting burning of claim 2 are wherein the burnable mixture includes a combustible material and fluid.

5. The method of effecting burning of claim 1 wherein there is a continuous supply of combustible materials and of further fluid.

6. The method of effecting burning of claim 1 wherein the combustible materials and/or further fluid are in a gaseous state.

7. The method of effecting burning of claim 1 wherein the combustible materials include propane or hydrogen gas.

8. The method of effecting burning of claim 5 wherein the further fluid is air.

9. A method of generating heat that uses the method of effecting burning of claim 1.

10. A method of processing waste that incorporates a method of effecting burning of claim 1.

11. A method of processing waste materials wherein the waste materials are used as or supplement the combustible material feed used in the method of claim 1.

12. A method of generating steam wherein water is introduced into the vortex used in the method of claim 1.

13. A continuous feed burner apparatus wherein in use at least one of a continuous feed and burnable mixture is introduced into a vortex having a high-pressure periphery and a lower pressure center; and

wherein passage of the vortex is through a downstream passageway;

wherein the vortex is caused to enter into a chamber which has a larger cross-sectional area and is caused to enter thereafter a passageway that is smaller than the chamber of larger cross-sectional area.

14. A heating apparatus having a vortex-forming chamber having an arrangement of apertures to effect a vortex of a type having a pressure at the center which is lower than the pressure at the periphery; and

wherein passage of the vortex is through a downstream passageway;

wherein the vortex is caused to enter into a further chamber which has a larger cross-sectional area and is caused to enter thereafter a passageway that is smaller than the further chamber of larger cross-sectional area.

15. The apparatus of claim 13 having a chamber with a downstream outlet passageway and at least one inlet aperture which is directed substantially at a right angle to a central axis of an inner cylindrical shape of the chamber in which one end is closed and the other end opens into a combustion area and where an inlet aperture is directed so it is other than directly aligned to intersect the said central axis.

16. The apparatus of claim 13 including a heat transfer element for transferring some of the heat from the combustion of the burnable mixture to an inlet location.

17. The apparatus of claim 15 wherein proximal to the inlet location there is an appropriate catalyst for permitting a thermocatalytic reaction to take place prior to introduction of the burnable mixture into the vortex.

18. The method of effecting burning of claim 2 wherein there is a continuous supply of combustible materials and of further fluid.

19. The method of effecting burning of claim 2 wherein the combustible materials and/or further fluid are in a gaseous state.

20. A method of processing waste that incorporates the method of effecting burning of claim 2.

21. A method of processing waste materials wherein the waste materials are used as or supplement the combustible material feed used in the method of claim 2.

22. A method of generating steam wherein water is introduced into the vortex used in the method of claim 2.

23. The apparatus of claim 14 having a chamber with a downstream outlet passageway and at least one inlet aperture which is directed substantially at a right angle to a central axis of an inner cylindrical shape of the chamber in which one end is closed and the other end opens into a combustion area and where an inlet aperture is directed so it is other than directly aligned to intersect the said central axis.