Note: Descriptions are shown in the official language in which they were submitted.
CA 02797467 2012-10-25
MULTIFLAME BURNER WITH FLAME TRANSFER
The present invention relates to a multiflame burner with
burner nozzles which can be loaded with fuel gas,
particularly for thermal material processing methods, a
burner nozzle of a multiflame burner of this type, which
can be loaded with fuel gas, and also a method for thermal
material processing, in which a multiflame burner of this
type is used.
Prior art
Although the present invention is described in the
following with reference to certain thermal material
processing methods, it may be emphasised that the
multiflame burners according to the invention can also
advantageously be used in other fields of application, just
like the corresponding burner nozzles. For example, the
present invention can be used for flame soldering, fusion,
for example of flame spray layers, hot forming and flame
hardening. Here, this may also in particular be methods for
preheating, postheating, soaking and hot forming, for
example in mechanical engineering, steel and container
construction. The invention can also for example be used
for drying, particularly for drying before sandblasting,
welding or marking.
For example flame heating according to DIN 8522 is a method
in which a workpiece is heated in order to change its
properties, for example in order to influence the
resistance to deformation.
Flame heating is also applied for preheating when welding,
cutting and in related methods of metal processing. For
example, during flame cutting, sheets of more than 30 mm
thick made of S355 steel are preheated to 89 to 128 C
directly before the cut. In the case of carbon steels,
CA 02797467 2012-10-25
2 -
temperatures of up to 200 C are used in welding methods to
this end, and in the case of alloy steels temperatures
between 100 and 400 C are used.
During scarfing, for example with acetylene, a burner
nozzle arrangement is directed onto a workpiece surface. As
a result, clean sheet surfaces for further processing can
be achieved and rust, rolling skin and scale layers can be
removed simply and in an uncomplicated manner. By scarfing,
in addition to metal, concrete and natural stone surfaces
can also be thermally treated, in order for example to
remove paintwork, coatings, oil contaminations or rubber
marks and to shape surfaces.
In the context of the presented applications, acetylene
burners are often used. Compared to other fuel gases,
acetylene has an exceptionally high flame temperature of
more than 3, O00 C, which inter alia can be traced back to
the positive enthalpy of formation of the acetylene
molecule (C2H2) . 8,714 kJ are released for thermal use per
kilogram of acetylene. These properties of acetylene are
therefore of particular interest in the case of thermal
heating processes, as here the heat is transferred faster
from the flame to the workpiece, the higher the temperature
of the burning flame. Further advantages of acetylene
include high ignition speed. The thermal efficiency is
better in the method mentioned, the faster the hot
combustion products impact onto the workpiece. This
requirement arises in particular during the heating of
metallic materials with high heat dissipation, for example
in the case of steel, copper and aluminium.
In the context of the methods mentioned, multiflame burners
are frequently used, that is to say burner arrangements
which have burner nozzles (individual nozzles) which are
supplied from a common fuel gas source. Multiflame burners
of this type are illustrated in Figures lA to 1C. Figure 1A
CA 02797467 2012-10-25
3 -
shows a conventional handheld burner, in Figure 1B a so-
called performance burner is illustrated and in Figure 1C a
lance burner is illustrated. The depicted burners have a
fuel gas supply 1 as common feature, by means of which
supply a gas mixture made up of acetylene and oxygen for
example is supplied. Burner nozzles 3 are attached on a gas
supply and holding apparatus or a burner base body 2.
Working flames 4 are formed in the case of discharging fuel
gas by means of the ignition of the burner nozzles 3. The
burner nozzles can have control and/or adjusting
apparatuses 5.
Before the use of a corresponding burner, all individual
nozzles are to be ignited manually or automatically for
example with pilot flames or ignition plugs. For the manual
ignition of the burner, a pilot flame is in this case
guided along the burner nozzles for example or it is
ensured by means of a back pressure that a flame forms at
all burner nozzles. For this, the burner is for example to
be held close to a correspondingly large metal sheet. The
operator of a corresponding apparatus is to ensure that a
flame forms at all burner nozzles (the mixture outlet
points). Whilst during the manual ignition, a visual check
of the ignition process is possible, this possibility is
not always present during the automated operation of a
corresponding burner, in which an automatic ignition also
generally takes place. For automated burner operation, the
so-called "propagating ignition" of all flames often causes
difficulties. For example, the suitability for propagating
ignition decreases if the burner is not orientated towards
a workpiece or the geometry of the workpiece is unsuitable
or the spacing between the burner nozzles is too large.
In the context of this application, "propagating ignition"
may be understood as meaning the transferring of a pilot
flame or burner flame from one burner nozzle to the next.
The further burner nozzles subsequently ignite one after
CA 02797467 2012-10-25
4 -
the other following the first burner nozzle, that is to say
ignite in a propagating manner.
If the propagating ignition is not successful, uncombusted
fuel gases can escape. If no additional safety precautions
are made, fuel gases accumulate in the surroundings of the
burner and a risk of explosion results.
Against this background, there exists the requirement for
multiflame burners with improved propagating ignition
properties.
Disclosure of the Invention
The invention suggests a multiflame burner with burner
nozzles which can be loaded with fuel gas, particularly for
thermal material processing methods, a burner nozzle for a
multiflame burner of this type, which can be loaded with
fuel gas, and also a method for thermal material processing
with the features of the respective independent patent
claims.
Preferred embodiments are the subject matter of the
respective subclaims and also the following description.
The term "fuel gas" may in the context of this application
be understood to mean pure fuel gases, for example
acetylene, methane, ethane, propane, butane, ethene,
methylacetylene or hydrogen, but also any desired suitable
gas mixtures and also mixtures which contain oxygen and
fuel gas, such as for example fuel gas/oxygen/compressed
air/intake air mixtures.
According to the invention, at least one of the burner
nozzles of a multiflame burner has at least one auxiliary
nozzle opening arranged laterally to a main nozzle
arrangement for generating a working flame. The same fuel
CA 02797467 2012-10-25
-
gas flows through the auxiliary nozzle opening as flows
through the main nozzle opening and the auxiliary nozzle
opening is advantageously in fluid communication with the
main nozzle opening and a fuel gas supply.
By means of the provision and a suitable arrangement of at
least one auxiliary nozzle arrangement, after the ignition
at least one auxiliary flame is formed, the orientation of
which has a directional component (vector component) in the
direction of the adjacent burner nozzle which is therefore
expediently orientated in the direction of a working or
auxiliary flame of an adjacent burner nozzle. By means of
the measures according to the invention, in this case the
transferring of a flame between individual burner nozzles
of a multiflame burner can be significantly improved. As a
result, a complete propagating ignition of all flames of a
multiflame burner can be achieved safely and reliably, if
the burner head spacing and the fuel gas quantity and/or
composition (for example of an acetylene burner) lies in
the functional range. By means of the measures according to
the invention, it is no longer necessary for the burner to
be orientated directly onto a workpiece. The danger of the
escaping of uncombusted fuel gases due to burners, which
are not ignited in a propagated manner, and also the risk
of explosion caused thereby is reduced or eliminated.
In the context of this application, "working flame" may be
understood to mean the respective main flame of a burner
nozzle of a multiflame burner, which is directed onto a
workpiece and for example is used for heating this
workpiece. The working flame is generally either created by
means of an individual nozzle, or else by means of a main
nozzle arrangement, in which a central nozzle is surrounded
by further nozzles arranged around the same. If, instead of
a main nozzle arrangement, an individual nozzle is
provided, this may be comprised in the context of the
invention by the term "main nozzle arrangement".
CA 02797467 2012-10-25
- 6 -
Accordingly, an "auxiliary flame" is the flame provided
according to the invention, effected by means of the
provision of at least one auxiliary nozzle opening, and
orientated at least to some extent onto an adjacent nozzle.
Typically, the auxiliary flames are smaller than the main
or working flames on account of smaller gas quantities or
volumetric flows flowing through the auxiliary nozzle
openings.
It goes without saying that the region of a "flame" is in
practice geometrically not clearly delimited, so that a
"working flame" and an "auxiliary flame" may also be flame
regions of a corresponding overall flame. Typically,
however, the primary flames, which are in each case
generated at the main and the auxiliary nozzle openings for
example of an acetylene burner nozzle, can be visually
clearly differentiated from one another at least to some
extent. The so-called stray flame forming around a primary
flame generally envelops the primary flame in the form of
an overall flame.
To form auxiliary flames in the direction of the at least
one adjacent burner nozzles, at least one auxiliary nozzle
opening and/or at least one nozzle channel assigned to a
corresponding auxiliary nozzle opening can be arranged at
an angle to the main nozzle arrangement and/or a nozzle
channel assigned to the same.
With particular advantage, particularly in the case of an
arrangement of a plurality of burner nozzles in a
multiflame burner in series or in a burner field, at least
one of the burner nozzles is provided with auxiliary nozzle
openings for generating auxiliary flames in the direction
of at least two adjacent burner nozzles. By means of this
arrangement, an auxiliary nozzle opening, through which
fuel gas flows, can following its ignition transfer a flame
CA 02797467 2012-10-25
- 7 -
directly to an adjacent auxiliary nozzle opening which is
not yet ignited but through which fuel gas flows. As a
result, the adjacent burner nozzle is ignited as a whole
and can for its part transfer the flame to at least one
further burner nozzle due to the arrangement of the
auxiliary nozzle openings, that is to say ignite a burner
arrangement in a propagating manner.
In order to achieve a particularly effective formation of
the auxiliary flames with advantageous geometries, a
multiflame burner of the type according to the invention
preferably has two, three or a plurality of auxiliary
nozzle openings on at least one side of the main nozzle
arrangement. By means of a corresponding arrangement,
overall a suitable configuration or cross-sectional
geometry of a burner flame and corresponding auxiliary
flames are effected. A cross-sectional geometry of this
type can be set in a targeted fashion, for example on the
basis of a spacing between individual burners and/or the
type or the pressure of a fuel gas used, so that a
particularly effective transfer of burner flames is
enabled.
As explained, a multiflame burner according to the
invention is set up so that at least one of the burners is
used for igniting at least one adjacent burner nozzle via
at least one auxiliary flame. This can for example be
achieved by suitable orientation of the auxiliary nozzle
openings, the geometry thereof, but also by means of
suitable spacing of the burner nozzles. On the basis of the
particular configuration of the burner nozzles with
auxiliary flames, it is only additionally necessary for
igniting a burner arrangement to ignite a burner, for
example in an automated manner, at a location, wherein a
safe propagating ignition of the overall burner is ensured.
CA 02797467 2012-10-25
- 8 -
With particular advantage, a multiflame burner according to
the invention can be constructed as a handheld burner or
machine burner, for example as a performance burner or
lance burner, particularly for operation with acetylene as
fuel gas. Lance and performance burners with linear burner
arrangement in particular benefit from the measures
according to the invention due to their poorer tendency to
ignite in a propagating manner.
A multiflame burner of the type mentioned has for ignition
at least one burner nozzle, a manual igniting apparatus, a
pilot flame, an ignition plug or a piezo igniter, as a
result of which the multiflame burner is suitable in
particular for automatic applications with non-manual
ignition.
For the features and advantages of the burner nozzle, which
is likewise provided according to the invention and can be
loaded with fuel gas, reference may explicitly be made to
the features of the previously mentioned multiflame burner.
In particular, a burner nozzle of this type, which can be
loaded with fuel gas, is constructed replaceably, so that
replaceable individual nozzles can be combined into a
burner base body for forming a multiflame burner and as a
result the flame transfer can be optimised. Also, for the
advantages and advantageous fields of application of the
method according to the invention, reference may be made to
the previously mentioned features.
Further advantages and configurations of the invention
result from the description and the attached drawing.
It is to be understood that the previously mentioned
features and the features which are still to be mentioned
in the following, can be used not only in the respectively
specified combination, but also in other combinations or
CA 02797467 2012-10-25
9 -
alone, without departing from the context of the present
invention.
The invention is schematically illustrated in the drawing
on the basis of an exemplary embodiment and is described in
detail in the following, with reference to the drawing.
Description of the figures
Figure 1 shows multiflame burners according to the prior
art in a schematic illustration.
Figure 2 shows a burner nozzle according to a particularly
preferred embodiment of the invention in a
perspective oblique view.
Figure 3 shows a burner nozzle arrangement according to a
particularly preferred embodiment of the
invention in a plan view from above.
Figure 4 schematically shows an arrangement of burner
nozzles according to a particularly preferred
embodiment of the invention, which are in
operation, in a side view.
As mentioned previously, the Figures 1A and 1C show
multiflame burners according to the prior art.
In the following figures, identical or components acting
the same manner are provided with identical reference
numbers. For the sake of clarity, a repeated explanation of
these elements is avoided.
Figure 2 shows a burner nozzle according to a particularly
preferred embodiment of the invention, designated as a
whole with 10, which can for example be used in a
multiflame burner according to the invention.
CA 02797467 2012-10-25
- 10 -
The burner nozzle 10 has a burner nozzle head 20 and a
burner nozzle base 21. If the burner nozzle 10 is a
replaceable nozzle, this can be fastened with the burner
nozzle base 21 in a burner base body. In the burner nozzle
head 20, a main nozzle arrangement 30 is provided, which
has a main nozzle opening and further nozzle openings
surrounding the same in a circular manner. The main nozzle
arrangement 30 is, as explained previously, set up for
forming a working flame.
In addition, the burner nozzle 10 has auxiliary nozzle
openings 40 provided in addition to the main nozzle
arrangement 30 for generating auxiliary flames. The
auxiliary nozzle openings 40 themselves or the
corresponding nozzle channels thereof can in this case be
angularly offset to the orientation of the main nozzle
arrangement 30, so that a targeted orientation of the
auxiliary flames in the direction of adjacent burner
nozzles or the flames thereof can be achieved.
In Figure 3, 4 burner nozzles 11, 12, 13, 14 overall are
illustrated according to a particularly preferred
embodiment of the invention in a plan view.
The burner nozzles 11, 13 and 14 correspond in terms of
configuration and arrangement to the auxiliary nozzle
openings 40 in this case of the burner nozzle 10 from
Figure 2. The burner nozzle 12 by contrast has auxiliary
nozzle openings 41 pointing perpendicularly downwards in
the figure, which are orientated in the direction of a
burner nozzle 14 arranged at right angles to the row of the
burner nozzles 11, 12 and 13. By means of the arrangement,
as is illustrated in Figure 3, a propagating ignition or
flame transfer, as is illustrated by means of the arrows
50, can be achieved with particular advantage between the
individual burner nozzles 11, 12, 13 and 14. The burner
CA 02797467 2012-10-25
- 11 -
nozzles 11, 12, 13 and 14 illustrated can in this case be
part of a multiflame burner or a burner field of a
multiflame burner. It goes without saying that the
configuration illustrated in Figure 3 can be expanded in
any desired manner and, if further auxiliary nozzle
openings 40, 41 are provided, a safe propagating ignition
50 can also be effected in additional directions.
In Figure 4, a corresponding burner nozzle arrangement in
operation is illustrated schematically. A fuel gas here
escapes from the burners 15 via a main nozzle arrangement
and laterally auxiliary nozzle openings 40 arranged
laterally thereto. As a result, the formation of a main
flame or working flame 60, which can be orientated onto a
workpiece, results. The primary flame of this working flame
is indicated with 70. In addition to the main flame 60 or
the primary flame 70 thereof, auxiliary flames 80 with
corresponding primary flames 90 are illustrated in Figure
4. The auxiliary flames 80 are orientated at least to some
extent in the direction of adjacent nozzles, as a result of
which the said particularly advantageous propagating
ignition results.
