Note: Descriptions are shown in the official language in which they were submitted.
CA 02996124 2018-02-20
ARRANGEMENT FOR THE ICE-FREE MAINTENANCE AND DE-ICING OF A WIND
TURBINE ROTOR BLADE
The invention relates to a construction arrangement for the ice-free
maintenance and de-icing of a
wind turbine rotor blade on the front edge of a rotor blade of a wind turbine,
comprising at least one
heating zone applied onto or integrated with the rotor blade which zone can be
controlled in a
cyclical and/or continuous manner, wherein the heating zone comprises at least
one electrical heating
element and is covered by a lightning protection system and is provided with
an erosion layer for
protection against corrosion.
Furthermore, the invention relates to an application method for a construction
arrangement for the
ice-free maintenance and de-icing of a wind turbine rotor blade for the ice-
free maintenance and de-
icing of a rotor blade on a rotor blade of a wind turbine.
Wind turbines have the problem that the rotor blades begin to ice over in
corresponding weather
conditions, in particular if the wind turbines are set up on rather high
locations. This partially also
uneven icing of the rotor blades can lead to an imbalance in the system and to
associated oscillations
as well as to the ejection of ice into the surroundings. This results in
absolutely very high yield
losses due to the icing of the rotor blades and also due to erroneous ice
sensors in the wind turbines.
Wind turbines in areas exposed to heavy icing often have up to 70 days
standstill during a winter (for
example at locations in Austria). A stoppage of about 15 days is cited here by
way of example for a
1.3 MW system which can be converted to Ã8000. It is even more extreme in the
case of 3 MW
systems in which the usual loss can amount to Ã30,000 in the case of 15 days
of standstill due to
icing. Even systems which are not in areas directly endangered by icing must
frequently be turned
off on account of the formation of ice so that on the whole there is a very
great demand for de-icing
devices.
Ice always forms only during the operation on the front edge of the rotor
blade so that a heating only
needs to be mounted there. Only a slight electrical heating performance is
necessary since only a
small surface must be heated and the heating only takes place on the surface
where the ice is created
and not inside the blade.
Various arrangements are known from the prior art for de-icing rotor blades of
wind turbines or for
keeping them ice-free.
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The closest prior art is probably the known prior art from the publication EP
2 826 993, from which
a wind turbine rotor blade de-icing method with a wind turbine rotor blade de-
icing system
arranged on a rotor blade is known in which modular electrical heating
elements which are
controlled cyclically, repeatedly, discontinuously and/or continuously,
wherein at least one modular
heating element is provided with a temperature sensor and/or electrical
resistance meters, wherein a
continuous measuring of environmental measured values takes place and the wind
turbine rotor
blade de-icing system is activated when given environmental measured values
are achieved.
Furthermore, this publication teaches a wind turbine rotor blade de-icing
system on a rotor blade of a
wind turbine which comprises at least two heating zones with modular heating
elements, wherein the
modular heating elements can be controlled cyclically and/or continuously, a
control system for
activating individual heating zones, main heating elements and/or air moisture
sensors for detecting
regulating magnitudes, wherein the sensors are evaluated by the control
system.
The main problem in the prior art is substantially the fact that there are no
anti-icing and de-icing
systems for retrofitting and that the implemented systems do not function
reliably. Therefore, there is
actually no effective solution and no appropriate system that actually
addresses and also effectively
solves the problem of ice formation in the icing of rotor blades of wind
turbines. A significant aspect
is the ability to apply such a de-icing arrangement to rotor blades of a wind
turbine here since this
application must be carried out on existing systems or systems which are
already operating, and it is
not possible in the prior art with the known arrangements and known methods to
efficiently mount
such de-icing arrangements in a field mounting and almost in any suitable
weather.
It was recognized in particular that in the case of de-icing arrangements in
the prior art for rotor
blades of a wind turbine that no durable total system is presently known since
the de-icing
arrangements known in the prior art all stop functioning after a short time on
account of the failure
of lines and the breakdown of the heating elements, wherein this can be the
case already after a few
days up to weeks.
The present invention has the basic task of indicating a construction
arrangement for the ice-free
maintenance and de-icing of a wind turbine rotor blade which can be readily
mounted, makes
possible a de-icing which is almost constant and efficient to operate, wherein
in particular the field
mounting, that is, directly on the wind turbine should take place. Therefore,
the settling of ice
should be avoided and eliminated and in addition it should be possible to make
local repairs. The
resistance and service life of such a de-icing arrangement is decisively
important here!
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This task is solved with a construction arrangement for the ice-free
maintenance and de-icing of a
wind turbine rotor blade according to the main claim and with a positioning
method for a
construction arrangement for the ice-free maintenance and de-icing of a wind
turbine rotor blade on
a rotor blade of a wind turbine according to the coordinate claim.
The construction arrangement for the ice-free maintenance and de-icing of a
wind turbine rotor blade
is built on the front edge of a rotor blade of a wind turbine, since it was
recognized that this area is
the decisive area for the formation of ice. The construction arrangement for
the ice-free maintenance
and de-icing of a wind turbine rotor blade comprises at least one heating zone
which is placed on
the front edge of the rotor blade when retrofitted, or is provided in
particular on the working side in
the case of new rotor blades and is integrated in the construction arrangement
for the ice-free
maintenance and de-icing of a wind turbine rotor blade , which heating zone
can be cyclically and/or
continuously controlled, wherein the heating zone comprises at least one
electrical heating element
and is provided with an erosion layer for protection against erosion. In this
regard the invention
provides that the electrical heating element or elements is/are adhered as a
graphite-containing
heating lacquer applied on a carrier film and which is applied on the rotor
blade as the first layer
with the carrier film, therefore, the carrier film on the rotor blade and
therefore the heating lacquer
on the carrier film. Furthermore, the electrical heating element or heating
elements are contacted by
flat strips consisting of copper or in particular copper alloys for the
current supplied to the electrical
heating element. An insulation film or an insulation lacquer is applied on the
electrical heating
system and then the lightning protection system, which is a copper film, is
applied on the insulation
film or the insulation lacquer. Finally, the erosion layer is applied on the
lightning protection system,
wherein the erosion layer is an erosion protection lacquer or an erosion
protection film.
As a result of this layered construction, it is possible for the first time to
use a construction
arrangement for the ice-free maintenance and de-icing of a wind turbine rotor
blade which can be
readily mounted, namely, for new rotor blades as well as for the subsequent
application of such a
construction on to present rotor blades, which construction makes it possible
to keep ice away and/or
de-ice it in a permanent fashion for several years since its resistance to the
movements of the rotor
blade on its surface is ensured.
The operating for many years is not possible at all until by this construction
of the de-icing
arrangement. The details of the individual components are important here.
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The decisive advantage of the disclosed construction arrangement for the ice-
free maintenance and
de-icing of a wind turbine rotor blade resides in the durability of the
construction, which actually
resists for the first-time temperature variations as well as the occurring
forces, in particular forces of
torsion and of traction present on the rotor blade surface!
The insulation film formed quasi adhesive on both sides in one exemplary
embodiment forms the
insulation layer between the heating film and the copper film. It forms the
separation of the current-
conducting and current-carrying planes and is located in an appropriate,
especially preferred
embodiment of course on appropriately provided flat copper strips which
conduct the current to the
heating zones and remove the current from the copper films.
The one or also several heating zones can in particular be realized by several
heating elements
individually connected to each other, wherein it is advantageous in this
regard that the application of
the individual heating elements which are, for example, 50 cm long, takes
place in sections and that
the individual sections of heating elements are connected to each other on
their front sides by flat
copper strips.
In order to achieve a uniform heating over the surface to be heated, the
individual sections of heating
elements of at least one heating zone are designed to be equally large
regarding their surface in order
that a more sufficient in uniform resistance can be realized in this manner.
In an especially preferred embodiment the flat strips are adhered with an
electrically conductive
adhesive to the heating elements so that the current conducted via the flat
strips to the heating
elements can also flow over a time lasting for years. It turned out in
particular that alternative joining
methods do not resist permanent use in reality so that interruptions in the
current supplied to the
heating elements occur.
Also, in an especially preferred embodiment the flat strips are manufactured
from copper beryllium
or a copper (beryllium copper) doped with beryllium. This hard and brittle
light metal surprisingly
proved to be especially suitable as an alloy additive to copper for this use
in the construction
arrangement for the ice-free maintenance and de-icing of a wind turbine rotor
blade.
It is especially advantageous if the insulation film is designed to be
adhesive on both sides since this
creates a ready manipulation for manufacturing the construction arrangement
for the ice-free
maintenance and de-icing of a wind turbine rotor blade.
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As an alternative, aside from an insulation film adhesive on both sides, an
insulation film adhesive
on one side can be used, wherein in particular the insulation film is provided
on the side facing the
rotor blade surfaces with an appropriate adhesive and can therefore be
prefabricated or
processed/worked in the prepared composite with the carrier film with the
heating lacquer arranged
on it. In this embodiment the copper film would then be provided subsequently
with an appropriate
adhesive so that the copper film, provided with the adhesive on the rotor
blade side, can be applied
onto the insulation film, which is not designed to be adhesive on this side in
this case.
Furthermore, it proved to be especially advantageous that the copper film is
surface-treated in order
to raise the adhesion. To this end, an appropriate activation, known in the
prior art, of the upper
copper layer is available so that a better adhesion is realized. Furthermore,
in order to raise the
durability, the copper film should contain almost very pure copper.
Furthermore, it is advantageous
if the copper film is rolled during the manufacturing process, which makes it
harder, and is annealed
after the rolling so that the copper film subsequently becomes more flexible
and soft again. In
particular, the copper film has a thickness of 0.1 to 0.2 mm. It is especially
preferred that the
thickness of the copper film for the lightning protection is 0.15 mm since
after this thickness no
material damage during constant use occurs after this thickness. In
particular, copper film can be
especially preferably used which was treated, for example, in an acid bath by
copper accumulations
additionally applied on the surface, wherein these copper films have a highly
active surface and enter
correspondingly well into an adhesive connection by an adhesive to the film or
films or to the
lacquer or lacquers.
Finally, the copper layer protects the heating layer from the action of a
lightning strike. The copper
layer is designed to this end in such a manner that the strongest lightning
strikes are received by it
during the impact and can be conducted away into the ground via appropriate
grounding devices or
also via the customary lightning protection system.
The graphite -containing heating lacquer on the carrier film can be present in
particular as graphite
or, however, also as carbon nanomaterials in conjunction with graphite.
Furthermore, it turned out
that a graphite-containing heating lacquer can be readily worked, and can be
applied especially onto
the carrier surface by a doctor blade method.
The layer thickness of the heating lacquer on the carrier film is in the range
of 20 pin to 160 gm.
The layer thickness of the heating lacquer is especially preferably in the
range of 20 m to 90 pm.
CA 02996124 2018-02-20
The layer thickness of the heating lacquer is especially preferably about 20
gm to 70 gm since at this
layer thickness the heating resistance necessary for the de-icing of the wind
turbine is realized.
The carrier film on which the heating lacquer is applied, as well as in
particular the insulation film
can consist in a preferred embodiment of polyethylene terephthalate [PET].
Furthermore, the
materials polyethylene [PE] or polyurethane [PU] are also suitable for forming
the films.
In a preferred embodiment the carrier film is designed to be flexible so that
it allows bidirectional
expansions along the surface.
The carrier film is treated electrochemically or by a plasma activation in an
especially preferred
embodiment prior to the application of the heating lacquer so that the
application of the graphite-
containing heating lacquer onto the carrier is possible with an especially
strong adhesion.
The erosion layer formed as lacquer is in particular a two-component lacquer
which is applied in the
range of at least 300 JIM to 600 gm layer thickness. A layer thickness of 300
gm proved to be
especially advantageous in this regard as regards the material consumption,
ability to apply it and
durability.
The shape of an erosion protection film which is also present with layer
thicknesses in the range of
200 gm to 600 gm, in particular 300 gm, and is applied or adhered on is also
preferred.
It turned out that in particular the adhesives to be used can be acrylate
adhesives which are used for
this bonding purpose. Acrylate adhesives are synthetically obtained adhesives
whose qualities are
distinguished by their high resistance to ageing and temperature as well as,
furthermore, by their
insensitivity to UV radiation and oxidation. Acid -containing as well as water-
based acrylic
adhesives can be used since in combination with the possible, oxygen-free
copper less complications
are to be expected even under special weather conditions (moisture,
temperature).
In order to contact the heating elements to each other and/or for the
contacting to an energy supply
connection on or in the rotor blades, in particular flat copper strips can be
provided. These flat
copper strips can be very readily arranged between the carrier film or
adjacent to the carrier film and
the insulation film /the insulation lacquer and can be very readily prepared
and applied during the
preparation process or the application process. In this connection the films,
namely the carrier film
for the heating lacquer and the insulation film, can be designed to be
appropriately larger so that the
flat copper strips for the conduction of the current can also be positioned
and housed on the films. A
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prefabrication of these flat copper strips for the current conduction with
simultaneous positioning on
the corresponding films can also be carried out in an especially preferable
manner.
Since appropriate lines must also be provided for supplying current and which
supply the heating
zones with current, according to the invention flat copper strips are also
included in the construction
of the position.
These copper strips are run in a special embodiment to contact points on the
rotor blades surface
where they are let in through the rotor blade via these contact points which
are let into the rotor
blades surface and terminate flush with the actual rotor blades surface where
they are connected to
the copper contacts. On the inside of the rotor blade normal cables to the
current supply are provided
inside the hub from these contact points. In particular, lead-throughs can be
provided in unloaded
areas of the rotor blade for running the electrical lines / flat strips
through for the heating elements
and/or for the lightning protection system, wherein these lead-throughs are
formed as copper bolts or
copper pins and are continued as round conductors at least in the inside of
the rotor.
It is also an especially preferred embodiment if the entire heating zone of a
rotor blade consists of at
least three heating zones and the individual heating zones are formed by
several heating elements,
for example, with a length of about 50 cm, which heating elements are
prefabricated. As a result,
they can be adhered on site onto the front edge of a rotor blade. These
elements are preferably a
prefabricated composite of carrier film adhering to the side of the rotor
blade and with the heating
lacquer applied on the side remote from the rotor blade and with the
insulation lacquer or insulation
film arranged on it and with the flat copper strips located between the
carrier film and the insulation
film. Furthermore, which is also an especially preferred design, the copper
films can be applied in
such a manner that another preparation step can be integrated in a
prefabricated manner. The
prefabricated, individual heating elements, in particular with the already
applied lightning protection,
are adhered one after the other in a very simple manner onto the front edge of
the rotor blade and are
covered after being adhered on by a final erosion layer. The films are
provided in an especially
preferred manner with appropriate overlappings. In addition, the edge areas
are formed in an
especially preferred embodiment with a projection of the actual area.
The corresponding application method according to the invention for a
construction arrangement for
the ice-free maintenance and de-icing of a wind turbine rotor blade on a rotor
blade of a wind turbine
with the corresponding construction comprises the following steps:
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I. Preparation of the rotor blade surface,
Adhering of the electrical heating element(s) by adhesion of the carrier film,
which is
provided with the graphite -containing heating lacquer, wherein the carrier
film is
adhered onto the prepared rotor blades surface and these electrical heating
elements
make contact with flat strips and/or these flat strips make contact with
supply lines
and/or supply points in or on the rotor blade surface,
III. Adhering the insulation film or applying the insulation lacquer on the
graphite -
containing heating lacquer, wherein the insulation film or insulation lacquer
covers the
graphite -containing heating lacquer at least completely,
IV. The adhering to the copper film onto the insulation film or the
insulation lacquer,
wherein the copper film covers the insulation film or the insulation lacquer
at least
completely, and
V. Application of the erosion layer on the copper film by adhering the
erosion protection
film or applying the erosion protection lacquer, wherein the erosion
protection film or
the erosion protection lacquer covers the copper film at least completely.
New as well as already existing rotor blades can be very readily retrofitted
by this previously
described method. The preparation of the rotor blade surface should of course
be considered
individually so that an older rotor blade, in particular the front edges of a
rotor blade, must be
repaired or restored as a rule so that a new surface or one comparable to new
is produced, whereas
on the other hand newer rotor blades perhaps only need to be cleaned or
inspected so that a surface
necessary for the adhering of the carrier film is present and also, finally,
the erosion protection
lacquer or the erosion protection film, which of course slightly extends past
the edge areas, can
adhere well to this surface.
In particular in a preferred embodiment the layers, which are applied one
after the other, are applied
past the edge area of the previous layer. This makes an additional protection
of the edge areas
possible, wherein this design is especially preferred since enormous forces
are present on the critical
front edge of the rotor blade by the wind. The overlapping of the layers also
additionally produces a
good aerodynamic construction of the surface.
For an optimal preparation of the application work and for increasing the
efficiency, the steps II and
III can be carried out together when using insulation film, wherein to this
end prior to the common
application of the carrier film with the graphite-containing heating lacquer
and the insulation film in
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one step, the carrier film with the graphite-containing heating lacquer is
applied onto the insulation
film. This creates a large savings potential as concerns the time for the
application during the
mounting in the field as well as in the case of new systems in the
manufacturing hall.
Contacts such as copper strips which are to be provided, namely for conducting
current into the
individual fields and current connections of the individual fields are applied
next to the graphite-
containing heating lacquer on the carrier film and/or on the insulation film
or underneath the
insulation film /the insulation lacquer. A preferred corresponding
construction can be realized here
by way of example in which the carrier film with the heating lacquer applied
on it distinctly projects
past the insulation film in its surface extension so that the flat copper
cables to be arranged lie next
to the carrier film on the rotor blade surface and are held quasi by the
insulation film on the rotor
blade surface. As a consequence of the distinct overlapping, the lower carrier
film with the heating
element can be kept small corresponding to the actual heating surface. The
current-conducting lines
are then applied and fixed with the aid of the insulation film since the
insulation film is constructed
to be clearly wider and therefore covers the current-conducting lines such as
the flat copper strips.
Furthermore, the contacts such as flat copper strips can also be provided at
least on one side with
appropriate adhesives so that they can be applied at least on one side in an
adhesive manner onto the
appropriate surfaces.
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