NL2034422B1 - Iron fuel combustion arrangement comprising an ignition device - Google Patents

Abstract

The present invention relates to an iron fuel combustion arrangement, comprising an iron fuel burner arrangement, a combustion chamber, and an ignition device for igniting a combustible medium comprising iron fuel provided by said iron fuel burner arrangement; wherein said ignition device is arranged for providing an auxiliary combustible medium, and comprises an ignitor for igniting said auxiliary combustible medium to create an ignition flame; wherein said ignition device is located at a distance of said iron fuel burner arrangement and said combustion chamber; wherein said iron fuel combustion arrangement further comprises an ignition channel having two ends, a first end being connected to said ignition device, and a second end being connected to said burner arrangement or said combustion chamber; wherein said ignition channel is arranged for transporting said ignition flame into said iron fuel burner arrangement or said combustion chamber, for igniting said combustible medium comprising iron fuel by said transported ignition flame. The present invention further relates to an ignition process for iron fuel ignition.

Description

TITLE Iron fuel combustion arrangement comprising an ignition device

TECHNICAL FIELD

The present invention relates to an iron fuel combustion arrangement.

Specifically, the present invention relates to an iron fuel combustion arrangement comprising an ignition device.

BACKGROUND

Energy is indispensable. The amount of energy consumed worldwide has increased enormously over the last decades. Although the amount of energy originating from renewable energy sources such as wind and solar has increased over the last decades and especially over the last years, a large part of the energy still originates from fossil fuels.

With the use of fossil fuels also comes the highly undesirable carbon dioxide, CO, emission. And in order to achieve climate objectives, the total CO: emission should be reduced significantly. To this end, carbon-neutral fuel, and even more carbon-free fuel, is a preferable source of energy and promising resource to fulfil worldwide energy requirements but still meet the climate objectives. Carbon- neutral fuel is considered fuel does not release more carbon into the atmosphere than it removes, whereas carbon-free fuel produces no net-greenhouse gas emissions nor carbon footprint at all. Typically, with carbon-neutral fuel, CO: or other greenhouse gasses are used as feedstock.

Heat intensive industries are responsible for a large part of the total

COz.emissions. But for many industries there are currently few or no fossil fuel alternatives available that on the one hand are scalable, and on the other hand able to provide sufficient energy with a high degree of certainty and consistency, yet are completely COz-emission-free.

Solar energy and wind energy can partly meet this need. However, due to the fact that they are intermittent, they are often not, or insufficiently suitable to replace fossil fuels and to meet the demand for energy from these industries at all times.

In recent years, a lot of research has therefore been carried out into a feasible alternative that is fully COz-emission-free. Iron fuel has the potential to meet that need and to become the candidate of choice.

Iron fuel is a very promising fuel in which energy is stored in the iron containing powder when and where needed. In the right conditions, iron powder is flammable and has the property that when the iron powder is burned, a lot of energy is released in the form of heat. This heat can then be converted into hot water, steam or electricity for use in any kind of application or industry. Another important property of iron powder is that only rust remains during combustion, while no CO: is released during the combustion of the iron powder. The rust, as a product, can be easily collected and converted back into the iron powder in a sustainable manner, which makes it a fully circular process.

The fact that the iron fuel is circular and easy and safe to transport makes it an ideal clean and sustainable alternative for fossil fuels to meet the demand for energy in various industries but also in all kinds of other applications.

Although the use of iron fuel may already be a proven clean and sustainable alternative to fossil fuels, there are also several challenges. One of the challenges lies in igniting the iron fuel. The functionality and performance of the arrangement should be optimized, and slagging and contamination of the ignition device should be avoided as much as possible. Contamination leads to mass loss of iron fuel in the circular process, and can also hamper the functionality of the ignition device. There is therefore a need to improve known burner processes suitable for iron fuel combustion in a way in which the ignition of iron fuel minimizes contamination of the ignition device.

SUMMARY

It is an object of the present invention to provide an improved iron fuel combustion arrangement.

It is a further object of the present invention to provide an iron fuel combustion arrangement with a controlled ignition process wherein contamination of an ignition device is kept at a minimum.

The present invention therefore relates in a first aspect to an iron fuel combustion arrangement comprising an iron fuel burner arrangement, a combustion chamber, and an ignition device for igniting a combustible medium comprising iron fuel provided by the iron fuel burner arrangement.

The ignition device is arranged for providing an auxiliary combustible medium, and comprises an ignitor for igniting the auxiliary combustible medium to create an ignition flame. The ignition device is located at a distance of said iron fuel burner arrangement and said combustion chamber.

The iron fuel combustion arrangement further comprises an ignition channel having two ends, a first end being connected to the ignition device, and a second end being connected to the burner arrangement or the combustion chamber.

The ignition channel is arranged for transporting the ignition flame into the iron fuel burner arrangement or the combustion chamber, for igniting the combustible medium comprising iron fuel by the transported ignition flame.

In a second aspect, the present invention relates to an ignition process for iron fuel ignition, in an iron fuel combustion arrangement according to the first aspect, comprising the steps of: - providing a combustible medium comprising iron fuel in a burner arrangement or a combustion chamber, - providing an auxiliary combustible medium, - igniting said auxiliary combustible medium with an ignition device according to any one of claims 1-10 to create an ignition flame, - transporting said ignition flame into said burner arrangement or said combustion chamber, - igniting said combustible medium comprising iron fuel by said transported ignition flame to provide a combusting iron fuel containing medium.

In a third aspect, the present invention relates to an ignition process for iron fuel ignition, in an iron fuel combustion arrangement according to the first aspect, comprising the steps of: - providing an auxiliary combustible medium, - providing a support combustible medium in a combustion chamber, - igniting said auxiliary combustible medium with an ignition device according to any one of claims 1-10 to create an ignition flame, - transporting said ignition flame into said combustion chamber, - ignition said support combustible medium by said transported ignition flame to provide a support flame,

- providing a combustible medium comprising iron fuel in said combustion chamber, - igniting said combustible medium comprising iron fuel by said support flame to provide a combusting iron fuel containing medium.

The present disclosure relates to a burner process for iron fuel combustion. More specifically, it relates to the ignition of iron fuel. The inventors have found that the known burner processes which are suitable for example for burning coal, coal-like material, waste and biomass are not suitable or less suitable for burning iron fuels. For burning iron fuel, specific process design requirements are applicable which are different from these known burner processes.

Burning iron fuel has different chemical and physical properties when compared to conventional fuels. Another difference is that iron fuel is intended to be used as a burnable clean energy medium in which the iron containing powder can be used in a circular manner, meaning that the residual product of the iron fuel after burning, i.e. the rust or iron oxide powder, is to be collected and should be suitable to be converted back into iron fuel. As mentioned, the properties of iron fuel are very different from other fuel types like diesel, coal or coal-like materials. As such, the parameters for traditional burning processes (including the methods of ignition) do not suffice and are not able to meet the requirements for such burner process in terms of i) general performance of iron fuel combustion arrangements and ii) for the purpose of reusing residual iron oxide powder.

When there is a need to ignite a combustible medium, an ignition device will usually be located such that it can directly ignite the combustible medium to be combusted. However, in the case of iron fuel an ignition device placed within the burner arrangement or the combustion chamber will not only disturb the conditions in the burner arrangement or the combustion chamber but also lead to slagging of iron particles in/on the ignition device and/or on the walls of the burner arrangement and/or combustion chamber. This will lead to hampered functionality or non-functionality of the ignition device, leading to a less reliable device requiring extensive maintenance (cleaning). It will further lead to mass loss of iron particles in the circular process.

Since the iron oxide particles that are the result of the combustion of iron fuel can be used again to make iron fuel, it is important to prevent mass loss of iron particles as much as possible. Furthermore, by physically (and thus temporally) separating the step of ignition of an auxiliary combustible medium from the step of ignition of the combustible medium comprising iron fuel, degradation of the iron particles is avoided because the risk of local thermal hotspots is minimized.

Without wishing to be bound by theory, the inventors believe the iron 5 fuel combustion arrangement according to the present invention, wherein the ignition device is located at a distance of the iron fuel burner arrangement and the combustion chamber, leads to minimal contamination (due to slagging or iron particles) and minimal mass loss of iron particles in the circular process. Minimizing contamination improves the reliability of the arrangement.

DESCRIPTION OF EMBODIMENTS

As stated above, the present invention relates to an iron fuel combustion arrangement, comprising an iron fuel burner arrangement, a combustion chamber, and an ignition device for igniting a combustible medium comprising iron fuel provided by the iron fuel burner arrangement.

Iron fuel has the potential to solve some of the major drawbacks of more typical renewable energy sources such as wind energy and solar energy due to the ability to store energy. Hence, energy obtained from renewable energy sources such as wind energy and solar energy can be stored in the iron fuel by which the intermittent character of these renewable energy sources is resolved by the iron fuel.

The combustion of iron fuel has the potential to meet the current demand of energy.

The combustion of iron fuel results in rust, or at least mostly in rust, and not in CO:. Iron fuel, comprising iron powder, can store energy and be used as a sustainable energy resource. With the iron fuel combustion arrangement according the present disclosure the iron powder can be combusted such that the energy stored in the powder is released. To this end the combustion arrangement may comprise several components or further arrangements, amongst which at least a combustion chamber and a burner arrangement.

The combustion chamber is arranged for combustion of the iron fuel at combustible conditions. To this end, the iron fuel is mixed with air, meaning at least comprising a certain amount of oxygen.

The burner arrangement may have a shape that widens towards the combustion chamber and may comprises several parts, amongst which a fuel feeder and air inlet means. The fuel feeder provides the iron fuel. The iron fuel is provided in a medium, gas or air which acts as a carrier and has thus for its main purpose to suspense the iron fuel in an air or air like medium. Preferably, the medium also contains additional components such as oxygen and more preferably also nitrogen and/or other substances or compounds.

The ignition device is arranged for providing an auxiliary combustible medium, and comprises an ignitor for igniting said auxiliary combustible medium to create an ignition flame. An ignition flame in the context of the present invention can also be defined as a combusting or combusted medium having a temperature sufficient to ignite the combustible medium comprising iron fuel. The ignition flame is not necessarily a visible flame.

The ignition device is located at a distance of the iron fuel burner arrangement and the combustion chamber. This prevents contamination of the ignition device by slagging of iron or iron oxide particles.

The iron fuel combustion arrangement further comprises an ignition channel having two ends, a first end being connected to the ignition device, and a second end being connected to the burner arrangement or the combustion chamber.

This ignition channel preferably is connected to an opening in the wall of the burner arrangement or the combustion chamber, without extending further into the burner arrangement or combustion chamber. If the channel would extend into the burner arrangement combustion chamber, this might influence the conditions (e.g. the flow) of the combustible medium comprising iron fuel, as well as form a possible surface for slagging of iron particles.

The ignition channel is arranged for transporting the ignition flame into the iron fuel burner arrangement or the combustion chamber, for igniting the combustible medium comprising iron fuel by the transported ignition flame. Physically separating the step of ignition of an auxiliary combustible medium from the step of ignition of the combustible medium comprising iron fuel avoids degradation of the iron particles because the risk of local thermal hotspots is minimized. Since the iron oxide particles obtained after combustion are to be converted back into iron fuel, degradation is to be avoided as much as possible.

Transport of the ignition flame through the ignition channel may take place because of an air flow present in the ignition channel. This air flow may be caused by inflowing air from air inlet means that may be connected to the ignition channel. This air flow may also be caused by a difference in pressure between the ignition channel and the burner arrangement or combustion chamber to which the ignition channel is connected. The air flow may be caused by expansion of the ignited auxiliary combustible medium, which expansion is directed towards the opening in the wall of the burner arrangement or the combustion chamber.

The ignition flame may come into contact with the combustible medium comprising iron fuel at the moment it enters the burner arrangement or the combustion chamber. However, it is also possible that the ignition flame is first further transported on an air flow present within the burner arrangement or combustion chamber. This air flow may also be described as a swirl. Further details can be found in WO2022NL50631 and NL2031419 of the same applicant, which applications are not yet published at the time of filing of the present invention.

When the combustible medium comprising iron fuel achieves a swirl pattern, it not only improves burning properties, but may also prevent or reduce deposition on the walls of the burner arrangement.

When the transported ignition flame comes into contact with the above-described swirl pattern, it may be transported further in this swirl pattern.

During this further transport, it may transfer heat to the combustible medium comprising iron fuel. In this way, the ignition flame serves as a heating means for the combustible medium, to heat the combustion medium until the temperature of at least part of the combustible medium has a minimum temperature equal to the ignition temperature of the iron fuel, igniting the combustible medium comprising iron fuel.

It is possible to define two phases of iron fuel combustion: a startup phase and an operational phase.

In an embodiment, said iron fuel combustion arrangement is configured for self-ignition of said iron fuel during an operational phase of said iron fuel combustion arrangement.

In an embodiment, said ignition device is configured to ignite said combustible medium comprising iron fuel in a startup phase, and said iron fuel combustion arrangement is arranged for self-ignition during an operational phase.

In view of the present description ignition is to be understood as either self-ignition of the medium in the right conditions, e.g. oxygen-to-fuel ratio, iron fuel solid density, mixture temperature, velocity, etc., but ignition may also be understood as an active step of direct ignition of the medium through ignition means or indirect igniting as for example pre-heating means to increase the temperature of the medium to such a degree that it ignites. Also, ignition may be interpreted as both pre-heating and actively igniting the medium through ignition means.

In an embodiment of the iron fuel combustion arrangement according to the present invention, said ignition device comprises a controller arranged for controlling the composition and/or supply of said auxiliary combustible medium. In a specific embodiment of this, said controller is arranged for controlling the composition and/or supply of said auxiliary combustible medium such that said auxiliary combustible medium is combusted prior to the ignition of said combustible medium comprising iron fuel.

A controller can generally be seen as a unit that controls certain aspects. This may involve the read-out of measurements and/or controlling. In case the controller is involved in read-out as well as controlling, it often concerns a proportional-integral-derivative (PID) controller. Controlling may take place via dedicated (embedded) hardware, often indicated as a microcontroller (MCU). This is commonly used in a broad range of electronics. It may also concern a general controller being a general purpose controller such as a CPU based system, or an industrial (larger) controller such as a programmable logic controller (PLC).

In a further embodiment, said ignition device comprises a controller arranged for controlling said ignitor.

In a further embodiment, said ignition device is arranged for providing one or more bursts of said auxiliary combustible medium.

In a further embodiment, said auxiliary combustible medium comprises oxygen and a combustible gas, said combustible gas preferably selected from methane, propane, butane, hydrogen, or a mixture thereof. The auxiliary combustible medium may for example be natural gas.

In a further embodiment, said iron fuel combustion arrangement further comprises a support arrangement for providing a support combustible medium in said combustion chamber, wherein said support combustible medium is arranged to be ignited by said transported ignition flame and for igniting said combustible medium comprising iron fuel.

In an example of this embodiment the ignition flame may be used to ignite a support flame which is located in the combustion chamber. The ignition flame enters the burner arrangement at the end of the channel, and travels (transports) along with an air flow swirling downwards in the burner arrangement towards the combustion chamber. This air flow does, in this example, not contain any iron fuel. In the combustion chamber, there is an inlet providing the support combustible medium. This medium is then ignited by the transported ignition flame. Once predetermined conditions - such as combustion chamber wall temperature, combustion chamber outlet temperature and/or emission parameters - are met, the iron fuel is added to the air flow. The arrangement may comprise sensors for determining temperature and/or gas composition. Addition of iron fuel to the existing air flow creates a combustible medium comprising iron fuel, and once this medium gets into contact with the support flame, the combustible medium can be ignited. In short: the ignition flame is used to ignite a support flame, which in turn ignites the combustible medium comprising iron fuel. The supply and amount of air flow and of iron fuel provided by the burner arrangement may be arranged by a controller. It is important in this case that iron fuel only enters the burner arrangement once the predetermined conditions are met.

In another example of this embodiment, the ignition channel is connected to the combustion chamber. In this example, the ignition flame may be transported through the ignition channel and at the end of the ignition channel ignite a support combustible medium which is present there. In this case, there is no need for an air swirl present in the burner arrangement or combustion chamber.

By only providing iron fuel when the predetermined conditions are met in the combustion chamber, the combustion conditions may be controlled in a more precise manner improving stability of the combustion.

The above specified embodiment including a support flame may be particularly beneficial for use for large-scale applications.

In a further embodiment, said support combustible medium comprises oxygen and a combustible gas, said combustible gas preferably selected from methane, propane, butane, hydrogen, or a mixture thereof. The support combustible medium may for example be natural gas.

In a further embodiment, said ignitor is arranged for electrical ignition or chemical ignition.

In a further embodiment, said ignition channel is placed at an angle of between 0 and 60° with respect to the longitudinal axis of the burner arrangement or combustion chamber. Preferably, the angle is such that it is substantially perpendicular to direction of the swirl that may be present in the burner arrangement or combustion arrangement. If the angle of the ignition channel is above 60°, the ignition flame may disturb the flow of the combustible medium comprising iron fuel in an undesired manner, leading to suboptimal conditions.

As stated above, the present invention relates in a second aspect to an ignition process for iron fuel ignition, in an iron fuel combustion arrangement according to the first aspect, comprising the steps of: - providing a combustible medium comprising iron fuel in a burner arrangement or a combustion chamber, - providing an auxiliary combustible medium, - igniting said auxiliary combustible medium to create an ignition flame, - transporting said ignition flame into said burner arrangement or said combustion chamber, - igniting said combustible medium comprising iron fuel by said transported ignition flame to provide a combusting iron fuel containing medium.

The skilled person will understand that the above indicated steps are not necessarily in chronological order. It is for instance possible that the provision of a combustible medium comprising iron fuel in a burner arrangement or a combustion chamber takes place during transport of said ignition flame.

As stated above, the present invention relates in a third aspect to an ignition process for iron fuel ignition, in an iron fuel combustion arrangement according to the first aspect, comprising the steps of: - providing an auxiliary combustible medium, - providing a support combustible medium in a combustion chamber, - igniting said auxiliary combustible medium to create an ignition flame, - transporting said ignition flame into said combustion chamber, - ignition said support combustible medium by said transported ignition flame to provide a support flame, - providing a combustible medium comprising iron fuel in said combustion chamber,

- igniting said combustible medium comprising iron fuel by said support flame to provide a combusting iron fuel containing medium.

The skilled person will understand that the above indicated steps are not necessarily in chronological order. However, it is important that for this aspect of the invention the provision of a combustible medium comprising iron fuel into the combustion chamber takes place only after ignition of the support flame. The support flame provides steady conditions within the combustion chamber, leading to more controlled combustion of the iron fuel.

The skilled person will understand that disclosed embodiments of the first aspect may also apply to the second and third aspect of the present disclosure.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope thereof.

The scope of the present invention is defined by the appended claims.

One or more of the objects of the invention are achieved by the appended claims.

DESCRIPTION OF DRAWINGS

The present invention is described hereinafter with reference to the accompanying drawings in which embodiments of the present invention are shown and in which like reference numbers indicate the same or similar elements.

Figure 1a and Figure 1b shows a schematic overview of two examples of an iron fuel combustion arrangement according to the present disclosure.

Figure 2 shows a schematic overview of another example of an iron fuel combustion arrangement according to the present disclosure.

Fig. 1a and 1b show a schematic overview of an iron fuel combustion arrangement 10 according to the present disclosure. The combustion arrangement 10 comprises several components which are divided over several sections of the arrangement.

The iron fuel combustion arrangement comprises a burner arrangement 12, 13 and a combustion chamber 14 and is thus typically divided into section A and section B, representing the burner arrangement and combustion chamber. Upstream 11 of said burner arrangement 12, 13 there can be further components such as a feeder mixing arrangement which mixes the iron fuel and a transport medium, which components are not shown in the figures. Also, downstream 15 of the combustion chamber 14 there can be further components such as a product area or after chamber, or a separation unit, which components are also not shown in the figures. These product area and separation unit are arranged to discharge the rust from the chamber and/or to separate the flue gases from the chamber.

The burner arrangement 12, 13 has several segments and comprises at least one segment 12, 13 in which the shape widens towards said combustion chamber. The widening of the burner can be achieved in several manners. The housing of the burner arrangement 13, near the combustion chamber 14, may be cone shaped, but other shapes may also apply. In particular the fuel feeder, 12 in the first segment of the burner arrangement may preferably be cylinder shaped, and the combustion chamber 14 is preferably cylindrical, cube shaped, or cuboid shaped. A segment of the burner arrangement 13 may be shaped such that a transition is provided from the shape of the fuel feeder 12, e.g. cylinder shaped, towards the shape of the combustion chamber 14, e.g. cube or cuboid shaped. As such, the segment of the burner arrangement 13 may be defined as a circle to square transition box.

The burner arrangement 12, 13 and the air inlet means are configured such that the iron fuel can be combusted in the combustion chamber 14, beyond a combustion interface 16, which is in Fig. 1 shown as a circular segment but which in a three-dimensional geometry preferably is a circular section, depending on the shape of the burner arrangement and/or the combustion chamber.

The iron fuel combustion arrangement 10 further comprises an ignition device 40 arranged for providing an auxiliary combustible medium. The ignition device 40 comprises an ignitor for igniting the auxiliary combustible medium to create an ignition flame. The ignition device 40 is located at a distance of said iron fuel burner arrangement and said combustion chamber.

The iron fuel combustion arrangement 10 further comprises an ignition channel 41 having two ends, a first end being connected to the ignition device

40, and a second end being connected to the burner arrangement 12, 13 (Figure 1a) or the combustion chamber 14 (Figure 1b).

It is expressed, that the position of the ignition channel shown in the figures are mere examples. The skilled person will understand that other positions may apply as well, for example in any wall section of the burner arrangement, or any wall section of the combustion chamber. In any of such examples, the channel opens into a wall section, providing a smooth transition, such that any protrusion of the channel into the burner arrangement or the combustion chamber is prevented, which protrusion may cause disruption of the combustion and contamination by adhesion of particles.

The ignition channel 41 is arranged for transporting the ignition flame into the iron fuel burner arrangement 12, 13 (Figure 1a) or the combustion chamber 14 (Figure 1b), for igniting the combustible medium comprising iron fuel by the transported ignition flame.

The ignition channel 41 is placed at an angle a with respect to the longitudinal axis of the burner arrangement or combustion chamber (a dashed line).

The angle a is preferably between 0 and 60°.

Figure 2 shows a schematic overview of a second example of an iron fuel combustion arrangement according to the present disclosure.

The combustion chamber is arranged for combustion of iron fuel which is fed from a fuel feeder 21. The iron fuel in the fuel feeder mixes with air from air inlets 22, 22a, 22b, 22c, 22d to create what is defined as an iron fuel suspension medium which comprises at least the iron fuel in the form of the iron fuel, and oxygen, both in such a mixture and under such conditions that, eventually in the combustion chamber, beyond the combustion interface 18, the medium can be combusted. To this end, the composition of the medium, the temperature, velocity and preferably also pressure define when, where and if the combustion conditions are reached. To this end, the amount of iron fuel, the speed, pressure and temperature of the iron fuel from the fuel feeder 21 as well as the amount of oxygen in the air, and the temperature, pressure and velocity of the air provided by the air inlet means 22, are controlled such the combustion conditions are reached in the combustion chamber, at or beyond the combustion interface 16.

The iron fuel is supplied trough a fuel feeder 21, in which the iron fuel is supplied in the form of a suspension medium in which the iron fuel is mixed with a transport medium such as air or gaseous medium comprising one or more of oxygen, nitrogen or other components.

Once the iron fuel exits the feeder, it is directed towards the combustion chamber with a certain speed. The iron fuel, when mixed with air from the air inlet means 22, is defined as an iron fuel suspension medium. The iron fuel suspension medium may be supplied in the burner arrangement such that the medium achieves a certain swirl pattern which comprises a rotational component to the medium flow. The swirl may be achieved by the shape of the fuel feeder, or by additional means added to the fuel feeder, the supply upstream of the feeder or by means added at or near the output of the fuel feeder, e.g. achieved by a baffle plate.

With the swirl pattern, turbulence is added to the iron fuel suspension medium which improves the mixing of the iron fuel and the oxygen in the air. The swirl may also increase the flow rate of the medium.

The swirl pattern of the iron fuel suspension medium may at least mostly provided by the air inlet means 22. When the fuel feeder 21 is arranged to provide the swirl pattern, the air inlet means 22 will further enhance the swirl, but in case the fuel feeder 21 supplies the iron fuel suspension medium in a more conventional manner, the air inlet means 22 will provide the swirl effect.

The air inlet means 22 cover all air inlet ports 22a, 22b, 22c, 22d as shown and located in the burner arrangement A, 12, 13 as shown in Fig. 1.

The air inlet means are arranged for supply of air comprising the oxygen and the means 22 comprise a first and a second inlet stage. The first inlet stage is arranged for the iron fuel suspension medium from said fuel feeder 21 to swirl towards the combustion chamber. The second inlet stage is arranged for the iron fuel suspension medium to be brought into a combustible condition beyond the combustion interface 1.

The second inlet stage is also arranged to provide a boundary layer between the iron fuel suspension medium and walls of the burner arrangement and the combustion chamber. What is meant with boundary layer in the present disclosure, is that the iron fuel suspension medium is guided towards the combustion chamber in such a way that no or at least less iron fuel deposition takes place at these walls of the burner arrangement, A, and/or the walls of the combustion chamber, B.

The first inlet stage may comprise the first air input ports 22a, 22b which are located closest to the fuel feeder. In such an embodiment, the air inlet ports 22a, 22b of the first inlet stage provide for the same medium characteristics such as temperature, oxygen content, velocity and pressure.

The first inlet stage is arranged to provide the swirl pattern, which is achieved by the configuration of the inlet stage or more particularly the air inlet ports 22a, 22b thereof. These inlet ports are positioned tangentially in the circumference wall of the burner arrangement. The first inlet stage to this end may have a tangential configuration of 2, 3, 4, 5 or more air inlet ports. Although not preferred, one or more of these inlet ports may also have an off-set towards the middle. In a transverse direction of the burner arrangement these air inlet ports may be positioned perpendicular or mostly perpendicular to the longitudinal direction of the burner arrangement, but alternatively, these may also be arranged at an angle such that the air injected into the burner arrangement is supplied in a direction with a forward component. The angle may be provided in longitudinal direction of the burner arrangement but also in the transverse direction thereof, or even in a combination of both.

The swirl pattern may however also be achieved by a different configuration of the first inlet stage, in which the air inlet is disposed coaxially in the circumference wall of the burner arrangement. In such a configuration the air inlet may be provided as a single, ring-shaped coaxial air inlet, but also as a plurality of air inlets disposed and distributed coaxially along the circumference wall of the burner arrangement.

In the example shown in figure 2, each of the inlet ports are disposed tangentially to provide for a swirl, wherein the first ports 22a, 22b, create the swirl form the cylindrically shaped feeder 21, whereas the other ports 22c, 22d, 22e, 22f, of the second inlet stage provide a further swirl effect to such a degree that the iron fuel suspension medium to is directed towards the combustion chamber in such a way that the medium still diverges but to a less degree than the diverging longitudinal cross-sectional shape of the walls of the burner arrangement such that the iron fuel suspension medium to is deflected from the wall of the burner arrangement but also from the walls of the combustion chamber.

In figure 2 the combustion chamber also shows additional air inlet ports 24a, 24b which provide a further input of air into the combustion chamber and to provide for a boundary layer between the iron fuel suspension medium and walls of the combustion chamber, also to prevent iron fuel deposition at the walls of the combustion chamber.

Figure 2 further shows a support arrangement with inlets 50 for providing a support combustible medium in the combustion chamber 14. The support combustible medium is arranged to be ignited by the transported ignition flame and for igniting said combustible medium comprising iron fuel. In this example, the ignition flame is used to ignite a support flame which is located in the combustion chamber 14.

The ignition flame enters the burner arrangement 12, 13 at the end of the channel 41, and travels (transports) along with an air flow swirling downwards in the burner arrangement 12, 13 towards the combustion chamber 14. This air flow does, in this example, not contain any iron fuel. In the combustion chamber 14, there are one or more inlets 50 for providing the support combustible medium. This medium is then ignited by the transported ignition flame. Once predetermined conditions - such as combustion chamber wall temperature, combustion chamber outlet temperature and/or emission parameters - are met, the iron fuel is added to the air flow. The arrangement may comprise sensors for determining temperature and/or gas composition. Addition of iron fuel to the existing air flow creates a combustible medium comprising iron fuel, and once this medium gets into contact with the support flame, the combustible medium can be ignited.

Claims (12)

CONCLUSIONS 1. An iron fuel combustion apparatus, comprising an iron fuel combustion apparatus, a combustion chamber, and an ignition device for igniting a combustible medium comprising iron fuel provided by said iron fuel combustion apparatus; wherein said ignition device is adapted to provide an auxiliary combustible medium, and wherein it comprises an igniter for igniting said auxiliary combustible medium to create an ignition flame; wherein said ignition device is spaced from said iron fuel combustion apparatus and said combustion chamber; wherein said iron fuel combustion apparatus further comprises an ignition channel having two ends, a first end being connected to said ignition device, and a second end being connected to said combustion apparatus or said combustion chamber; wherein said ignition channel is adapted to convey the ignition flame into said iron fuel combustion device or said combustion chamber, for igniting said combustible medium comprising iron fuel by said conveyed ignition flame. 2. An iron fuel combustion apparatus according to claim 1, wherein said ignition device comprises a controller for controlling the composition and/or supply of said combustible auxiliary medium. 3. An iron fuel combustion apparatus according to claim 2, wherein said controller is adapted to control the composition and/or supply of said combustible auxiliary medium such that said combustible auxiliary medium is combusted prior to ignition of said combustible medium comprising iron fuel. 4. An iron fuel combustion apparatus according to any preceding claim, wherein said ignition device comprises a controller adapted to control said igniter. 5. Iron fuel combustion apparatus according to any one of the preceding claims, wherein said ignition device is adapted to provide one or more pulses of said combustible auxiliary medium. 6. An iron fuel combustion apparatus according to any preceding claim, wherein said combustible auxiliary medium comprises oxygen and a combustible gas, said combustible gas preferably being selected from methane, propane, butane, hydrogen, or a mixture thereof. 7. An iron fuel combustion apparatus according to any preceding claim, wherein said iron fuel combustion apparatus further comprises a support device for providing a combustible support medium in said combustion chamber, wherein said combustible support medium is adapted to be ignited by said conveyed ignition flame and to ignite said combustible medium comprising iron fuel. 8. An iron fuel combustion apparatus according to any preceding claim, wherein said combustible support medium comprises oxygen and a combustible gas, said combustible gas preferably being selected from methane, propane, butane, hydrogen, or a mixture thereof. 9. An iron fuel combustion apparatus according to any preceding claim, wherein said igniter is adapted for electrical ignition or chemical ignition. 10. An iron fuel combustion apparatus according to any preceding claim, wherein said ignition channel is disposed at an angle of between 0 and 60° relative to the longitudinal axis of the combustion apparatus or combustion chamber. 11. Ignition process for iron fuel ignition, in an iron fuel combustion apparatus according to any one of claims 1 to 10, comprising the steps of: - providing a combustible medium comprising iron fuel in a combustion apparatus or a combustion chamber, - providing a combustible auxiliary medium, - igniting said combustible auxiliary medium with an ignition device according to any one of claims 1 to 10 to create an ignition flame, - transporting said ignition flame into said combustion apparatus or said combustion chamber, - igniting said combustible medium comprising iron fuel by said transported ignition flame to provide a burning iron fuel-comprising medium. 12. Ignition process for iron fuel ignition, in an iron fuel combustion apparatus according to any one of claims 1 to 10, comprising the steps of: - providing a combustible auxiliary medium, - providing a combustible supporting medium in a combustion chamber, - igniting said combustible auxiliary medium with an ignition device according to any one of claims 1 to 10 to create an ignition flame, - conveying said ignition flame into said combustion chamber; - providing a combustible medium comprising iron fuel in a combustion chamber, - igniting the said combustible medium comprising iron fuel by the said supporting flame to provide a burning iron fuel-comprising medium.