Note: Descriptions are shown in the official language in which they were submitted.
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Device and method for crushing rock by means of pulsed electric energy
Background
The present invention relates to a method for processing material at the
bottom of
a body of water, like the bottom of the sea, by application of electric
energy,
comprising providing electrodes in a process zone proximate the material for
providing
electric energy for crushing the material.
W09924694 (Al) relates to a method for crushing rock by means of pulsed
electric energy. Costs of a dredging project may rise high as a result of a
small volume
percentage of rock, because the device used is unsuitable for dredging this
material.
Additionally it is not always possible to use explosives. Therefore W09924694
(Al)
aims to crush rock in a simple manner into pieces of a small size and provides
therefore
a method for crushing rock comprising the generation of a shock wave with a
preprogrammed form, strength and length of time for crushing rock. W09924694
(Al)
alleges that because the shock wave is given such a preprogrammed form,
strength and
length of time, the crushing of rock produces a desired size of pieces, and/or
the
crushing of rock takes place over a desired surface of the rock and/or the
crushing of
rock takes place up to a desired depth in the rock.
WO 2006/023998 A2 relates to pulsed electric rock drilling, fracturing and
crushing methods on land. Herein a number of techniques are described to
process
material by application of electric energy through electrodes.
RU2008118585 relates to electro hydraulic breaking and crushing method for
solid materials. Two electrodes are placed inside a cylindrical airtight
housing. Shock
waves are precisely directed through hollows and linings arranged on the
housing.
In connection with processing material by application of electric energy, US 5
845 854 A shows an example of a method, for use on land, of solid insulator
destruction which destroys solid insulators by electric pulse discharges. The
method of
US 5 845 854 A is not suitable for offshore use.
With the known methods, the effect in terms of crushed rock is poor, in
particular
when executing prior art methods in seawater. There is room for improvement in
that
respect.
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Summary of the invention
The invention aims to provide a more effective method for processing material
at
the bottom of a body of water, like the bottom of the sea, by application of
electric
energy. More effective has to be understood as more crushed rock per applied
electric
energy.
Another object of the invention is to improve a known method for processing
material at the bottom of a body of water by application of electric energy,
in that a
problem associated therewith is at least partly solved.
Yet another object of the invention is to provide an alternative method for
processing material at the bottom of a body of water by application of
electric energy.
According to a first aspect of the invention this is realized with a method
for
processing submerged material at the bottom of a body of water, like the
bottom of the
sea, by application of electric energy, comprising providing electrodes for
application
of the electric energy in a process zone proximate the material for crushing
the
material, and displacing of fluid of the body of water away from the process
zone to
outside the process zone before application of the electric energy.
The displacing of fluid of the body of water away from the process zone to
outside the process zone before application of the electric energy enables to
lower the
electrical conductivity in the process zone and therefore more electric energy
is applied
to the material. As a consequence, more crushed material at the bottom of the
sea is
obtained. Usually, the submerged material comprises rock.
This type of method is in the art referred to with e.g. pulsed power
technology,
fracturing rock is the plasma-hydraulic (PH) or electrohydraulic rock
fracturing, and
spark discharge drill. While the method specifies the processing of the
material at the
bottom to crushing, the processing may also include fracturing, pulverizing,
eroding
etc.
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The method according to the invention is particularly useful when laying
pipelines on the bottom of the sea. In performing the method, obstacles, like
boulders
or men made concrete structures, can be removed so that the pipe laying can
continue.
In an embodiment of the method, the displacing of fluid of the body of water
away from the process zone comprises introducing an electrically insulating
body in the
process zone.
In an embodiment of the method, the displacing of fluid of the body of water
away from the process zone comprises introducing an electrically insulating
fluid under
pressure in the process zone. It will be apparent that the insulating fluid
may be a gas, a
liquid or a mixture thereof
The electrically insulating fluid has a low electrical conductivity, in
particular
below 500 mS/m, more particular below 50 mS/m.
According to an aspect of the invention the method comprises on site producing
the electrically insulating fluid.
In an embodiment of the method, fluid of the body of water is partly displaced
away from the process zone to outside the process zone such that a layer of
fluid of the
body of water remains on top of the submerged material before application of
the
electric energy. This way, it is possible to create a shockwave in the layer
of fluid of the
body of water on top of the submerged material. This shockwave then has its
crushing
effect on the submerged material. In this embodiment the electric energy is
applied to
the submerged material indirectly through the layer of fluid.
In an embodiment of the method, substantially all fluid of the body of water
is
displaced away from the process zone to outside the process zone such that the
application of the electric energy causes providing an electric current
through the
material. In this embodiment the electric energy is applied directly to the
submerged
material.
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According to a further aspect of the invention this is realized with a device
for
processing submerged material at the bottom of a body of water, like the
bottom of the
sea, by application of electric energy, wherein the device comprises
electrodes
configured to be arranged in a process zone proximate the material for
providing an
electric current through the material, and means for displacing fluid of the
body of
water away from the process zone to outside the process zone before
application of the
electric energy.
In an embodiment of the device, the means for displacing fluid of the body of
water comprises an electrically insulating body arranged proximate the
electrodes.
In an embodiment of the device, the means for displacing fluid of the body of
water comprise a discharge opening arranged proximate the electrodes for
introducing
an electrically insulating fluid under pressure in the process zone.
In an embodiment, the device comprises a container filled with the
electrically
insulating fluid, which container is in fluid connection with the discharge
opening. The
electrically insulating fluid may be pressurized with any suitable means, like
a pump.
In an embodiment, the device comprises a shielding member arranged around the
process zone for holding the electrically insulating fluid in the process
zone.
In an embodiment, the device comprises measuring means arranged in the
process zone for measuring electrical conductivity in the process zone.
In an embodiment of the device, the electrodes comprise a pair of concentric
electrodes. This pair of concentric electrodes is in particular useful when a
layer of
fluid of the body of water remains on top of the submerged material before
application
of the electric energy. As described above, it is then possible to create a
shockwave in
the layer of fluid of the body of water on top of the submerged material. This
shockwave then has its crushing effect on the submerged material.
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The invention further relates to a device comprising one or more of the
characterising features described in the description and/or shown in the
attached
drawings.
The invention further relates to a method comprising one or more of the
5 characterising features described in the description and/or shown in the
attached
drawings.
The various aspects discussed in this patent can be combined in order to
provide
additional advantages.
Description of the drawings
The invention will be further elucidated referring to embodiments shown in the
schematic drawings wherein shown in:
Fig. 1 in side view electrodes in a process zone while executing a prior art
method;
fig. 2 in side view electrodes in a process zone while executing a method
according to the invention;
fig. 3 in side view a device according to the invention for processing
submerged
material at the bottom of the sea by application of electric energy; and
fig. 4 in side view a further embodiment of a device according to the
invention.
Detailed description of embodiments
Fig. 1 shows in side view electrodes 1 in a process zone while executing a
prior
art method. The process zone is filled with sea water 4. Because of the
electrical
conductivity of seawater, a discharge 12 between the electrodes 1 will take a
path
through the seawater and will therefore not have a desired effect of crushing
the
submerged material 6.
Fig. 2 shows in side view electrodes 1 in a process zone 2 while executing a
method according to the invention. The electrodes 1 are arranged proximate the
material 6 at the bottom of the body of water 4. Here, the electrodes 1 do not
contact
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the material 6. The submerged material 6 at the bottom of the sea, is
processed by
application of electric energy, shown as a spark 12. Seawater 3 is displaced
(see fig. 3
and 4), that is removed, from the process zone 2 away from the process zone 2
to
outside the process zone 2 before application of the electric energy. As a
result, the
electric energy is more effective in terms of crushed material at the bottom
of the sea.
Usually, the material 6 at the bottom of the sea comprises rock.
Fig. 3 shows in side view a device according to the invention for processing
submerged material 6 at the bottom of the sea by application of electric
energy. The
fluid of the body of water 4 is displaced away from the process zone 2 through
introducing an electrically insulating body 5 in the process zone 2. The
electrically
insulating body is an example of a means for displacing fluid of the body of
water 4
away from the process zone 2 to outside the process zone before application of
the
electric energy. The electrically insulating body 5 is arranged proximate the
electrodes
1. Here, the electrically insulating body 5 extends between the electrodes 1.
In this
case, the electrically insulating body 5 contacts the material 6 at the bottom
of the sea.
In dashed line, the electrically insulating body 5 is shown in a position
wherein
the fluid of the body of water is partly displaced away from the process zone
to outside
the process zone. In this position of the electrically insulating body 5, a
layer of fluid of
the body of water remains on top of the submerged material before application
of the
electric energy. This way, it is possible to create a shockwave in the layer
of fluid of the
body of water on top of the submerged material. This shockwave then has its
effect on
the submerged material. In this embodiment the electric energy is applied to
the
submerged material indirectly through the layer of fluid.
Fig. 4 shows in side view a further embodiment of a device according to the
invention. The device is provided with a nozzle 8 as a means for displacing
fluid of the
body of water 4 away from the process zone 2 to outside the process zone 2
before
application of the electric energy. The nozzle 8 is arranged proximate the
electrodes 1.
The nozzle introduces an electrically insulating fluid 7 under pressure in the
process
zone 2. The electrically insulating fluid 7 displaces fluid of the body of
water 4 away
from the process zone 2 to outside the process zone 2. The electrically
insulating fluid
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under pressure has a low electrical conductivity, in particular below 500
mS/m, more
particular below 50 mS/m.
In this case, the electrically insulating fluid is produced on site. To store
the
insulating fluid 7, the device comprises a container 9 filled with the
electrically
insulating fluid 7. The container 9 is in fluid connection with the nozzle 8.
The
insulating fluid 7 is pressurized by any suitable means.
As an option, the device has a shielding member 10 for holding the
electrically
insulating fluid 7 in the process zone 2. The shielding member 10 is arranged
around
the process zone 2 for holding the electrically insulating fluid 7 in the
process zone 2.
As a further option, the device comprises a measuring means 11 for measuring
electrical conductivity in the process zone 2. The measuring means 11 is
arranged in
the process zone 2.
In dashed line, the possibility is shown that the fluid of the body of water
is partly
displaced away from the process zone to outside the process zone such that a
layer of
fluid of the body of water remains on top of the submerged material before
application
of the electric energy. This way, it is possible to create a shockwave in the
layer of fluid
of the body of water on top of the submerged material. This shockwave then has
its
effect on the submerged material 6. In this embodiment the electric energy is
applied to
the submerged material 6 indirectly through the layer of fluid.
It will also be obvious after the above description and drawings are included
to
illustrate some embodiments of the invention, and not to limit the scope of
protection.
Starting from this disclosure, many more embodiments will be evident to a
skilled
person which are within the scope of protection and the essence of this
invention and
which are obvious combinations of prior art techniques and the disclosure of
this
patent.
