Note: Descriptions are shown in the official language in which they were submitted.
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Title
Iron fuel combustion arrangement
Technical Field
The present disclosure relates generally to iron fuel burner
technology. More specifically, relates the present disclosure to iron fuel
combustion
arrangements which comprises a combustion chamber and a burner arrangement.
Background of the Invention
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, 002, emission. And in order to achieve climate objectives, the total
002
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
fulfill 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
or
carbon footprint at all. Typically, with carbon-neutral fuel, 002 or other
greenhouse
gasses are used as feedstock.
Heat intensive industries are responsible for a large part of the total
002-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 002-emission-free.
Solar energy and wind energy can partly meet this need. However,
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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 002-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
powder when and where needed. In the right conditions, iron powder is highly
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 CO2 is
released
during the combustion of the iron powder. The rust, as waste 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
most important challenges is the fact that the iron fuel, when combusted, has
the
tendency to contamination in the burner or the combustion arrangement.
Therefore,
the uptime of the combustion is limited, as parts of the combustion
arrangement
needs cleaning from time to time. This does not aid the potential as an
alternative to
fossil fuel combustion. There is therefore a need to reduce the effect of
combustion.
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Summary
It is an object of the present disclosure to provide an improved iron
fuel combustion arrangement. More particular, it an object to provide for an
improved
iron fuel combustion arrangement which has a higher uptime, and which is less
prone
to contamination.
In a first aspect, there is provided, an iron fuel combustion
arrangement, comprising a combustion chamber and a burner arrangement, said
combustion chamber being arranged for combustion of an iron fuel suspension
medium comprising iron fuel and oxygen at a combustible condition, said burner
arrangement having a shape that widens towards said combustion chamber, and
wherein said burner arrangement comprises:
a fuel feeder, arranged for supply of iron fuel in said combustion
chamber, wherein said iron fuel is provided in a transport medium.
air inlet means, arranged for supply of air comprising said oxygen to
said iron fuel, said air inlet means comprising a first and a second inlet
stage, said
first inlet stage being arranged for said iron fuel suspension medium to swirl
towards
said combustion chamber, and said second inlet stage being arranged to provide
a
boundary layer between said iron fuel suspension medium and walls of said
burner
arrangement and said combustion chamber for preventing iron fuel deposition at
said
walls, and characterized in that said second inlet stage is further arranged
for said
iron fuel suspension medium to be brought into a combustible condition beyond
a
combustion interface in said combustion chamber.
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 002. Iron fuel, comprising iron powder, can store energy and be
used as a
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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
powder at combustible conditions. To this end, the iron powder is mixed with
air,
meaning at least comprising a certain amount of oxygen.
The burner arrangement has a shape that widens towards the
combustion chamber and comprises several parts, amongst which at least a fuel
feeder and air inlet means. The fuel feeder provides the iron powder. The iron
powder
is provided in a medium, gas or air which acts as a carrier and has thus for
its main
purpose to suspense the iron powder 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 air inlet means are arranged to supply the air into the
arrangement. The air contains oxygen and has the purpose of mixing with the
iron
powder to create a medium or mixture of iron powder and oxygen in desired
ratio and
under desired conditions in which the iron fuel can combust and more precisely
combust under defined conditions.
The mixture of iron powder and oxygen, as defined in the present
disclosure, is considered a medium which comprises iron powder and oxygen,
meaning that it also may contain other substances, compounds or mixtures,
amongst
which nitrogen, minerals, organic compounds or contaminations, although the
main
components will be considered the iron powder and oxygen.
An important condition for the combustion of the medium of iron
powder and oxygen is the temperature, as it was an insight of the inventors
that the
temperature must be kept below a sintering temperature, i.e. in accordance
with the
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definition of sintering temperature as defined by ASTM E228 ¨ 17.
When iron powder reaches the sintering temperature, it becomes in
a sintering condition which could result in clogging of the arrangement and a
loss of
5 iron powder, which should be prevented.
It was a further insight of the inventors that, in order to bring the
medium to an optimal condition for combustion under desired process conditions
in
which sintering conditions prevented such that clogging or other contamination
is
prevented, the air inlet means should have at least two stages, of which the
first stage
being arranged or configured to create the medium and thus to provide oxygen
for
the desired mixture of iron powder and oxygen, whereas the second stage has
for its
main purpose to provide a boundary layer between the medium and the walls of
the
arrangement to prevent iron fuel deposition at the walls of the arrangement,
i.e. at the
walls of either the burner arrangement, the combustion chamber but preferably
both.
The inventors found out that the iron fuel deposition on the walls has
an effect on the durability and robustness of the arrangement and the quality
and
stability of the combustion process and thus decreases the uptime because the
arrangement has to be cleaned from this deposit from time to time. The
deposition
may even be that heavy that the burner or even other components of the
arrangement
cannot be cleaned anymore and should be replaced instead.
By adding an extra air inlet stage, which air inlet stage is configured
such that it provides provide a boundary layer between the medium and walls of
the
burner arrangement and the combustion chamber, the iron fuel deposition at
those
walls is prevented. As such, not only is it prevented that the iron powder
deposits at
the walls, the second air inlet stage also prevents sintering of the iron
powder
upstream of the combustion chamber, and thus in the burner arrangement.
The inventors also found out that conventional, known combustion
arrangements typically rely on pre-mixing and nozzles to provide the
combustible
medium, or in other words, to bring the suspension medium into such a
condition in
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which it can be ignited. Although the pre-mixing may be configured to a
certain desired
combustible properties with respect one or more of density or fuel / oxygen
ratio,
pressure, velocity, etc., these properties are influenced significantly and to
a certain
degree uncontrollably, by the nozzle. The design of the arrangement according
to the
present disclosure differs from such typical designs in the absence of a
nozzle.
Contrary to such known designs, with the arrangement according to the present
disclosure, the medium is brought into a combustible condition within the
combustion
chamber, and not at the start of the chamber. Conventional designs typically
have
ignition means near the nozzle to ignite the medium, which results in a non-
optimal
condition for combustion and undesired and less controlled process conditions,
which
increases sintering conditions that may lead to clogging and/or wear of
components.
The arrangement according to the present disclosure has a first air inlet
stage which
is arranged for said iron fuel suspension medium to swirl towards said
combustion
chamber, but also a second inlet stage, which provided both the boundary layer
between the medium and walls but is further characterized in that it also
brings the
medium from a non-combustible condition or at least from a undesired and non-
optimal condition for combustion, into a combustible condition. The
combustible
condition is obtained at and beyond what is referred to as the combustion
interface.
Hence, by virtue of the configuration of the second air inlet, the position of
the
combustion interface can be controlled, which position is beyond the start of
a first air
inlet port of the second inlet stage.
In an example, said second inlet stage is further arranged for said
iron fuel suspension medium to be brought into a combustible condition beyond
said
combustion interface, and wherein said second inlet stage comprises at least
two air
inlets disposed in the circumference wall of said burner arrangement, and said
combustion interface to be configured to be disposed beyond at least one of
said two
air inlets of said second inlet stage.
The combustion interface may in an example have a hyperbolic,
parabolic shape or cross-section or a cone shaped three-dimensional shape.
Preferably, the interface concentrates towards the fuel feeder or upstream.
Accordingly, the medium may be brought into a combustible condition beyond
such
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shape of interface, such that at least at a or more preferably, some, and even
more
preferably, all positions of the interface lie beyond at least an air inlet of
the second
inlet stage.
In an example, said iron fuel combustion arrangement is configured
for self-ignition of said iron fuel suspension medium at or beyond said
combustion
interface, during an operational phase of said iron fuel combustion
arrangement.
In an example, said iron fuel combustion arrangement comprises an
open connection between said fuel feeder and said combustion chamber.
Conventional combustion arrangements rely on a nozzle which is
configured to bring a combustion medium into a combustible condition. Hence,
in
accordance with the present disclosure, the iron fuel combustion arrangement
could
be provided with a nozzle between the fuel feeder and the combustion chamber
or in
other words, at the start or upstream of the combustion chamber. However, in
an
example, the iron fuel combustion arrangement according to the present
disclosure
is provided without a nozzle and thus configured to comprise an open
connection or
open pass way or channel between the fuel feeder and combustion chamber. As
such,
any swirl of the suspension medium is not cancelled out or influenced by the
nozzle,
as in known combustion arrangements. Accordingly, the second inlet stage can
be
arranged for the iron fuel suspension medium to be brought into a combustible
condition not at the beginning (upstream) of the combustion chamber, but at a
certain
position in the combustion chamber, what is defined as combustion interface.
Hence,
the medium is only then combustible at or beyond this interface. Additionally,
the
second inlet stage is arranged to provide the boundary layer between the iron
fuel
suspension medium and walls of the burner arrangement and the combustion
chamber for preventing iron fuel deposition at one or more of these walls.
In an example, said fuel feeder is arranged for axial supply of iron
fuel in said combustion chamber, wherein said iron fuel is provided in a
transport
medium. Also, preferably, the first and/or second inlet stage may be
configured for
tangential and/or axial inlet of air. More preferably, the first inlet stage
may be
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configured for tangential air inlet.
In an example, one or more of said first and second inlet stage
comprise at least two air inlets disposed tangentially in the circumference
wall of said
burner arrangement.
In an example, one or more of said first and second inlet stage
comprise at least one air inlet disposed coaxially in the circumference wall
of said
burner arrangement.
In an example, one or more of said first and second inlet stage
comprise at least two air inlets disposed at an angle with said wall of said
burner
arrangement.
In an example, one or more of said first and second inlet stage
comprises a plurality of guide vanes disposed on said burner arrangement wall
for
providing said boundary layer.
In an example, said plurality of guide vanes are adjustable.
In an example, one or more of said first and second inlet stage
comprise multiple groups of air inlets distributed along a longitudinal axis
of said
burner arrangement.
In an example, a wall of one or more of said first and second inlet
stage or a section of a wall between air inlets of one or more of said first
and second
inlet stage along a longitudinal axis is diverging, converging or parallel.
In an example, one or more of said air inlets of one or more of said
first and second inlet stage are comprised in an airbox housing.
In an example, one or more air inlet ports of said air inlets of one or
more of said first and second inlet stage are connected to an air duct.
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In an example, said first inlet stage has an at least approximately
cylindrical cross-section.
In an example, said second inlet stage has a circular or polygon
shaped cross-section.
In an example, said combustion chamber has a cylinder or polygon
three-dimensional shape, or a three-dimensional shape defining a transition
across a
longitudinal direction from a circular shape to a polygon or more preferably
rectangular shape, or vice versa.
In an example, said second inlet stage comprises a baffle plate for
central recirculation of in said arrangement, and for improving the flow
direction to
prevent iron fuel deposition at said walls.
In an example, said combustion chamber comprises in a first section
of said combustion chamber:
an igniter for igniting said iron fuel suspension medium at said
combustible condition in said combustion chamber, and wherein said igniter is
preferably an electrical igniter or a chemical igniter.
In an example, said ignitor extends up to said combustion interface.
In an example, said ignitor extends up to said combustion interface,
and wherein said second inlet stage comprises at least two air inlets disposed
in the
circumference wall of said burner arrangement, and said ignitor is disposed
beyond
at least one of said two air inlets of said second inlet stage.
In an example, said ignitor is configured to ignite said combustible
medium at or beyond said combustion interface in a startup phase, and wherein
said
iron fuel combustion arrangement is arranged for self-ignition during an
operational
phase.
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In an example, said second inlet stage comprises:
a pre-heating element for pre-heating said iron fuel suspension
medium to create said iron fuel suspension medium to be brought to said
combustible
5 condition, and wherein said pre-heating element is preferably an
electrical heating
element or a chemical heating element.
In an example, said combustion chamber comprises a first and a
second section, wherein said second section is disposed downstream of said
first
10 section, and wherein one or more of said first and second section
comprise film air
inlet means, wherein said film air inlet means being disposed in a wall of
said
combustion chamber and arranged to provide a boundary layer between said iron
fuel
suspension medium and walls of said combustion chamber for preventing iron
fuel
deposition at said walls of said combustion chamber.
In an example, any one or more of the air inlets and fuel feeder is
connected to an output of said combustion chamber for recirculation of flue
gas into
said combustion chamber, and wherein said iron fuel combustion arrangement
further
preferably comprises a filter downstream of said combustion chamber for
filtering
combusted medium from said iron fuel suspension medium.
In an example, the iron fuel combustion arrangement further
comprises:
an iron fuel tank, connected with said fuel feeder for storage of said
iron fuel.
- an iron fuel feeding system, connected with said iron fuel tank and
said fuel feeder for mixing said iron fuel with said transport medium.
In an example, any one or more of the fuel feeder and the one or
more air inlets comprise a control valve for control of the supply of air of
said
respective inlet.
In an example, any one or more of the fuel feeder and the one or
more air inlets are arranged for supply of air of said respective inlet at a
raised
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temperature, which raised temperature is preferably below a sintering
temperature of
said iron fuel suspension medium.
The invention will now be described in more detail by means of
specific embodiments, with reference to the enclosed drawings, wherein equal
or like
parts and/or components are designated by the same reference numerals. The
invention is in no manner whatsoever limited to the embodiments disclosed
herein.
Brief description of the Drawings
Fig. 1 shows a schematic overview of an iron fuel combustion
arrangement;
Fig. 2 shows a cross-sectional view of an iron fuel combustion
arrangement according to an aspect of the present disclosure;
Fig. 3-5 show cross-sectional views of air inlets according to an
aspect of the present disclosure;
Fig. 6 shows a cross-sectional view of an example of an iron fuel
combustion arrangement according to an aspect of the present disclosure;
Fig. 7 shows a cross-sectional view of another example of an iron
fuel combustion arrangement according to an aspect of the present disclosure.
Detailed Description
Fig. 1 shows 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 powder and
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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 powder 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.
In Fig. 2 a first example is shown of a cross-section of an iron fuel
combustion arrangement according to the present disclosure. The combustion
arrangement comprises a combustion chamber and a burner arrangement as shown
in Fig. 1 and defined by A and B, respectively. The combustion chamber is
arranged
for combustion of iron fuel which is fed from a fuel feeder 21. The iron
powder 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 powder, and oxygen, both in such a mixture and under such
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conditions that, eventually in the combustion chamber, beyond the combustion
interface 16, 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
powder,
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 powder 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 powder
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 powder exits the feeder, it is directed towards the
combustion chamber with a certain speed. The iron powder, 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 according to the present disclosure
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. The baffle plate or baffle for short, may
provide or add
to the direction of the air flow and/or the combustible medium.
With the swirl pattern, turbulence is added to the iron fuel suspension
medium which improves the mixing of the iron powder 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 is 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
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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 as shown in Fig. 2. The second inlet stage is
arranged for the iron fuel suspension medium to be brought into a combustible
condition beyond the combustion interface 16 as shown in Fig. 2.
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.
According to the present disclosure, 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
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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
5 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
10 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.
Figures 3, 4 and 5 show different examples of air inlet means, e.g.
15 the air inlet means of the first inlet stage. In Fig. 3 a tangential
configuration is shown
having two inlet ports 22a, 22b, whereas in Fig. 4 a similar configuration is
shown but
with three inlet ports, 22a, 22b, 22c. The configuration in Fig. 5 shows the
coaxial
placed inlet stage in which the iron fuel suspension medium is brought into a
swirl
pattern swirling from the fuel feeder 21 towards the combustion chamber.
The second inlet stage, as shown in figure 2 with reference 22c, 22d,
is arranged for the iron fuel suspension medium to be brought into a
combustible
condition. What that means is that the oxygen and iron powder is mixed at a
desired
ratio and in which preferably also certain desired velocity, pressure and
temperature
of the medium is reached. The air inlet velocity is preferably in the range
between 10
and 100meter per second [m/s], more preferably between 20 and 60 m/s. The
temperature is preferably in the range between 25 (ambient) and 300 degrees
Celsius
[ C], more preferably between 60 and 200 degrees Celsius [ C]. The second
inlet
stage 22c, 22d, is arranged such that the medium can reach a combustible
condition
not at the first inlet stage 12, not at the second inlet stage 13, both shown
in figure 1,
but in the combustion chamber B, 14 downstream of the combustion interface 16.
The second inlet stage 22c, 22d, not only brings the iron fuel
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suspension medium into a combustible condition beyond a combustion interface
16
in the combustion chamber 14, but also provides a boundary layer between the
iron
fuel suspension medium and walls of the burner arrangement A, 12, 13, and the
combustion chamber B, 14, 15 for preventing iron fuel deposition at any one or
more
of these walls.
The second inlet stage is in figure 2 shown and embodied as a
second pair, 22c, 22d of inlet ports which are disposed tangentially in the
circumference wall of the burner arrangement A. It is however emphasized that
this
is merely an example, as these may also be embodied differently, for example
in the
form of a coaxially disposed inlet which is arranged in the circumference e of
the wall
of the burner arrangement. Also, a variant may be embodied in which the second
inlet
stage is configured by inlet ports disposed at an angle with the wall of the
burner
arrangement. Moreover, these embodiments may also be combined into a
combination of inlet ports having different configurations and/or in which the
second
inlet stage comprises for example two groups of inlet ports as shown in
figures 6 and
7. A groups of air inlet ports can be defined as those inlet ports providing
the same
characteristics into the combustion chamber or the burner arrangement, e.g. in
which
inlet ports provide air at any one or more of the same angle into the chamber,
the
same velocity, pressure and temperature.
The air inlet ports of the first and/or of the second inlet stage may not
only have different configurations in terms of positioning at or near the wall
of the
burner arrangement, but may also have different shapes and can for example be
.. configured as a pipe, a hole in the wall or comprise guide vanes to force
the air into
a desired direction. Also the shape or geometry of the inlet ports may be
constant in
longitudinal direction, or may be diverging or converging, and may also be
configured
to achieve a venturi-effect in which the velocity of the air is increased due
to the a
decrease in cross-sectional area or diameter of the inlet. The guide vanes may
be
configured to direct the air stream into a desired direction and has the
advantage that
the desired direction of air flow can be configured in an efficient and
relative simple
manner. By selection of material, shape, location and amount, a highly
configurable
air flow can be achieved. The guide vanes may not only be configured to direct
the
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air into a certain desirable direction, but also to add rotation to the air
stream, e.g. to
provide or add to the swirl of the air stream.
The wall of the burner arrangement may also have different
.. longitudinal shapes. In particular the wall sections of the first and/or
the second stage
in between the inlet ports may be consistent in longitudinal direction or may
be
diverging or converging towards the combustion chamber, alternatively, these
may
also be stepped or staged. Various examples are for shown in the figures 6 and
7, in
which the wall sections are staged or stepped by discrete steps in increasing
diameter
towards the combustion chamber, as shown in figure 6, and an example in which
the
wall sections have a diverging geometry.
The longitudinal distance between the inlet ports may be constant
but may also differ per group or even per port.
The burner arrangement 12, 13 and in particular the shape thereof
configured to have a cross-section as a cylinder, or a polygon. The combustion
chamber 14 may also have a cylindrical or polygon shaped cross-section, or a
cross-
section which consists of a transition from a cylinder to a polygon or vice
versa, e.g.
to provide a transition between the shape of the burner arrangement and the
combustion chamber. The burner arrangement itself may also have a cross-
section
which consists of a transition from a cylinder-shaped part of the feeder 12 to
a polygon
shaped cross-section of the first/second stage.
Figure 6 and figure 7 show alternative embodiments with several
differences in the features of the iron fuel combustion arrangement according
to the
present disclosure. Especially the air inlet means, and the shape of the wall
sections
differ between the two examples. For example, in figure 6 the air inlet means
comprise
six main air inlet ports 22a, 22b, 22c, 22d, 22e, 22f, belonging to the first
and second
stage of the burner arrangement. The first inlet stage comprises two inlet
ports 22a,
22b, which provide the swirl to the iron fuel suspension medium, and the
second inlet
stage comprises two groups 22c, 22d and 22e, 22f of inlet ports which provide
the
boundary layer between the iron fuel suspension medium and walls of the burner
arrangement and the combustion chamber to prevent iron fuel deposition at the
walls.
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In the example shown in figure 6, 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 6 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.
In figure 7 the inlet ports are configured differently than those in
figure 6. In figure 7 the first inlet stage is defined by the ports disposed
tangentially,
22a, 22b, 22c, 22d, 22e, 22f. The second inlet stage is defined by the inlet
port 22g,
which is configured as a single coaxial inlet.
Further the wall of the second stage of the air inlet means is also
different as compared to figure 6, as these show a more gradient transition in
increase
of diameter of the second stage, whereas the example shown in figure 6 shows a
stepped increase in diameter.
The additional air inlet means 24a, 24b may also comprise more inlet
ports than those shown in the examples of figures 6 and 7 as these may also be
disposed and distributed along a longitudinal direction over the wall of the
combustion
chamber. Moreover, these may also have different shapes and configurations in
accordance with the examples described in relation to inlet ports of the first
and/or
second stage.
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Based on the above description, a skilled person can provide
modifications and additions to the method and arrangement disclosed, which
modifications and additions are all comprised by the scope of the appended
claims.
