Note: Descriptions are shown in the official language in which they were submitted.
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"Method for removing a polluting substance from a water
surface"
* * *
TEXT OF THE DESCRIPTION
The present invention relates to a method for
removal of a pollutant floating on a body of water, in
particular petroleum and/or its derivatives. In
particular, the present invention regards a method of
removal that envisages the use of absorbent material.
Methods of this type are already widely known in
the art. In general, these methods envisage dipping the
absorbent material in the pollutant, and subsequently
gathering it after it has been impregnated with said
substance.
The object of the present invention is to provide
a method of the type referred to above that will be
more efficient and economically advantageous than those
of the known art.
Said object is achieved by a method having the
characteristics specified in Claim 1..
The claims form an integral part of the technical
teaching provided herein in relation to the invention.
The invention will now be described, purely by
way of non-limiting example, with reference to the
annexed representations, in which:
- Figure 1 illustrates a watercraft
for
implementing the method described herein;
- Figure 2 illustrates a schematic perspective
view of the inside .of the watercraft of Figure 1;
- Figure 3 illustrates a side view of the
watercraft of Figure 1;
- Figure 4 illustrates a top plan view of the
watercraft of Figure 1;
- Figure 5 is a diagram of a system for
implementing the method described herein; and
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- Figure 6 is an axonometric view of a system for
providing the method described herein. .
Illustrated in the ensuing description are various
specific details aimed at providing an in-depth
understanding of the embodiments. The embodiments may
be obtained without one or more of the specific
details, or with other methods, components, or
materials, etc. In other cases, known structures,
materials, or operations are not illustrated or
described in detail so that the various aspects of the
embodiment will not be obscured.
The references used herein are provided merely for
convenience and hence do not define the sphere of
protection or the scope of the embodiments.
The method described herein has the purpose of
removing a pollutant, in particular a floating liquid
hydrocarbon substance, for example petroleum and/or its
derivatives, from a body of water. To remove said
pollutant, the method described herein envisages the
use of absorbent material.
The method described herein is characterized in
that the absorbent material used is greasy animal wool,
with large fibres, preferably sheep's wool. In
particular, the wool used in the method described
herein has fibres of a diameter greater .than or equal
to 25 m, preferably between 25 and 40 m. By "greasy"
wool is meant wool straight off the animal that has not
yet been subjected to any washing treatment.
The present applicant has found that the type of
wool referred to above has specific characteristics
that render it particularly suited to the application
referred to herein.
In the first place, the present applicant has
found, through an intense experimental activity, that
the type of wool in question has a capacity of
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absorption of hydrocarbon substances, specifically
liquid hydrocarbon substances, that is decidedly higher
than the majority of absorbent materials used in the
known art. Said higher absorption capacity would seem
to be attributable at least in part to the diameter of
the fibres of the wool used. Moreover, it has been
found experimentally that wool of the type indicated
can be re-used many more times than is instead allowed
with the materials commonly used in this type of
applications (which for the most part are plastic-resin
or glass synthetic materials), enabling as a whole up
to ten times the amounts that can be absorbed by said
conventional materials.
In the second place, the present applicant has
found that said type of wool is able to absorb
selectively only the hydrocarbon substances and not
also the water on which these float, as instead occurs
with conventional absorbent materials. The present
applicant has found that said property is typical of
greasy wool, which, since it has not been in fact
subjected to any washing treatment, is coated with a
layer of grease that renders it water-repellent. It is
thus evident that said type of wool guarantees, in the
field of the applications in question, results that are
decidedly better than conventional absorbent materials,
above all in terms of efficiency of absorption, not
only because it has a greater capacity for absorbing
hydrocarbon substances, but also because it is able,
given that it does not absorb water, as instead said
conventional materials do, to exploit its capacity
fully. In the greasy wool used here, the layer of
grease and of equivalent substances is present in a
weight percentage of between 15 wt% and 60 wt%.
Furthermore, apart from the properties referred to
above, the use of said type of wool for the method in
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question brings with it also the following advantages:
- any possible dispersion in the environment of
the wool does not create ecological problems in so far
as it is a product of natural and biodegradable origin;
- no containers are needed in so far as it has an
intrinsic cohesion of its own that prevents dispersion
thereof;
- the marked interaction between the wool of said
type and petroleum enables removal of patches of
petroleum in an effective way, minimizing the
hydrocarbon substance residue on the surface of the
water;
- it floats on the water also after absorbing the
petroleum and it is thus possible to recover it easily;
- its effectiveness of action is not impaired by
the wave motion, which rather, thanks to the mechanical
action on the petroleum-water interface, is even
positive for the purposes of absorption in so far as it
improves penetration of the petroleum into the wool;
- it resists organic solvents and is thus not
damaged by petroleum;
- the. wool impregnated with the hydrocarbon
substance absorbed can be used as combustible material,
for example within incinerator systems;
- it is easily available practically throughout
the world, and is cheaper than fine-fibre wool.
The method described herein can envisage different
specific embodiments. In general, said method envisages
dipping the wool in the hydrocarbon substance and then
taking it out after it has been impregnated with said
substance. Preferred embodiments can envisage that the
impregnated wool is squeezed in order to separate and
collect in a tank the hydrocarbon substance that has
been absorbed, and, subsequently, that the squeezed
wool is re-used for removing further amounts of said
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substance.
In what follows two different types of systems
will be described for implementation of the method
described herein.
As will be seen hereinafter in detail,. the first
system, illustrated in Figures 1 to 4, is designed to
be installed on a watercraft and has been obtained
specifically for interventions on the open sea, for
removal of large patches of hydrocarbon pollutant,
-whilst the second system, illustrated in Figures 5 and
6, has been specifically devised for interventions in
confined bodies of water, such as ports, canals, or
lakes, or in any case for interventions in which the
amounts of pollutant to be removed are decidedly
smaller. It is clear that each of the two types of
system can in any case be effectively used for both
types of intervention referred to above.
WATERCRAFT FOR INTERVENTIONS ON THE OPEN SEA
In general, the watercraft described herein is
equipped with a system that enables operation during
advance of the watercraft itself. In particular, as
will be seen in what follows, said system is pre-
arranged for generating, exploiting precisely the
motion of advance of the watercraft, a continuous flow
of absorbent material in bulk form, which from the
watercraft is let down into the sea, directly on the
patch of pollutant, and is then brought back again onto
the watercraft.
In particular, the -system has:
- a frame designed to delimit laterally a strip of
body of water that extends along at least one of the
sides of the watercraft;
- means for lowering absorbent material in bulk
form into said strip of body of water;
- a conveying surface for bringing back onto the
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watercraft the absorbent material previously let down,
said surface having a portion immersed in said strip of
water, which occupies a position that, with respect to
where the absorbent material is let down, is set at a
distance in the direction opposite to that of advance
of said watercraft, said portion being designed to
intercept the absorbent material lowered into said
strip; as will be seen in what follows, the elements
referred to above, which make up the system, are all
mounted on the watercraft and are carried by the
latter.
Illustrated in Figure 1 is an example of
watercraft on which the system in question is to be
installed. It is clear that the watercraft can in any
case be also of any other type; for example, it can
also be a simple floating structure without means of
propulsion of its own, which must then be towed by
another watercraft.
In various embodiments, as in the ones illustrated
in Figures I and 2, the aforesaid frame comprises a
guard 4, which extends along one side of the watercraft
and at a given distance therefrom, is anchored to the
watercraft, by means of purposely provided lattices 6
arranged on the deck of the watercraft, and is rendered
floating by means of buoys 5 anchored to it. The
lattices engage the guard 4 so as to enable this to
move vertically with respect to the lattices, in order
to remain on the surface of water, in one and the same
condition partially immersed, whatever the plane of
floating of the watercraft.
The guard constitutes a divisory element of the
free surface - or of a slightly deeper portion - of the
body of water, which delimits, together with the side
of the watercraft facing it, a channel 8 (which is
obviously limited laterally but not on the bottom). In
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various embodiments, as in the one illustrated, the
guard extends substantially from bow to stern. As will
be seen in what follows, said channel prevents the
absorbent material from dispersing and, at the same
time, conveys it, as a result of the headway of the
watercraft, towards the conveying surface referred =to
above, designated by the reference number 12 in the
figures.
In various embodiments, as in the ones illustrated
in the figures, the aforesaid means (designated by the
reference number 16 in the figures) for lowering the
absorbent material, i.e., the tufts of wool, in the
sea, into the channel 8, are set on the watercraft so
as to be able to let down said material at the end of
said channel closest at the bow of the watercraft,
whilst the conveying surface 12 is set so as to be
immersed in said channel substantially at the end of
this closest to the stern. In preferred embodiments,
the aforesaid means envisage an alternating movement
that enables distribution of the tufts of wool
substantially throughout the width of the channel 8. In
various embodiments, as in the ones illustrated in
Figures 1 and 2, said means are formed by a set of
chutes and/or conveyor belts 16, the last of which
terminates beyond the side of the watercraft for
casting said material into the Channel 8. In various
embodiments, as in the ones illustrated in the figures,
pre-arranged on the watercraft is a storage area,
designated by the reference number 18, where containers
containing the greasy wool to be used in the system are
arranged. Set instead in a position corresponding to
the lowering means 16 are tufting units 17 designed to
break the wool taken from the container up into tufts.
In various embodiments, as in the ones illustrated
in Figures 1 and 2, the conveying surface 12 is an
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inclined conveying surface, which is anchored to the
watercraft, and which from the level of the deck of the
watercraft reaches the surface of the sea until it is
immersed, at least partially, in the channel 8, in the
proximity of the end of the latter closest to the
stern. In various embodiments, as in the ones
illustrated in Figures 1 and 2, the surface 12 is
formed by a mesh conveyor belt, driven by appropriate
means (not illustrated), which is made to advance in
the direction of ascent of the surface defined thereby.
Said belt has the function of intercepting the
absorbent material present in the channel and of
bringing it back on to the deck of the watercraft. It
will be appreciated that the mesh structure of the belt
enables interception and collection of the absorbent
material, reducing to a minimum the resistance exerted
by the water, against the belt as a result of advance
of the watercraft.
In various embodiments, as in the ones illustrated
in Figures 1 and 2, set downstream of the conveying
surface (with reference to the direction of the flow of
absorbent material that will be described in what
follows) is a further conveyor belt, designated by the
reference number 22, which is designed to bring the
material gathered as far as an opening 26 where a set
of squeezing rolls 24 is located, designed to squeeze
the absorbent material for separating from this the
pollutant, which ends up in the tank 19 inside the hull
of the watercraft. Downstream of said rolls, two
conveyor belts 15 and 27 are provided, designed to
bring the absorbent material that has been squeezed
back again to the lowering means 16. Set instead
underneath the lowering means 16, a store 14, where the
exhausted absorbent material that is no longer usable,
which is conveyed there by the belts 27 and 15
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themselves, is gathered; in this case, the belt 15
reverses its direction of advance so as to discharge
the material carried by the belt 27 into the store 14.
In various embodiments, as in the ones illustrated
in Figures 1 and 2, in order to improve the absorption
of the pollutant by the absorbent material, a freely
rotating set of rolls 25 is provided within the
channel, which are carried by the same frame as the one
that. carries the guard, and are kept in a position
raised with respect to the hull of the watercraft so as
to remain immersed in the water and to be set in
rotation as a result of the advance of the watercraft.
In any case, the rolls 25 can also be motor-driven so
as to render their movement of rotation independent of
the speed of advance of the watercraft. Said rolls have
the function of agitating and mixing the absorbent
material contained in the channel 8.
In various embodiments, as in the ones illustrated
in the figures, the same configuration described above
can be provided in a symmetrical way on both sides of
the watercraft.
In view of the above, it is consequently evident
that, in order to operate, said system requires the
watercraft to advance along the area of sea involved by
the patch of pollutant so that said substance is
brought into the channel, and the continuous flow of
absorbent material referred to above (which will be
described in detail hereinafter) is triggered. It
should be noted that, during advance of the watercraft,
within the channel there converges not only the liquid
of the body of water that it delimits but also the
liquid that is displaced by the hull of the advancing
watercraft itself. Consequently, to all effects the
portion of surface of water that is involved in the
process of depuration is substantially the same as the
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one comprised in the encumbrance defined between the
guard and the central part of the bottom of the hull of
the watercraft; this means that in the case
illustrated, where the system envisages the same
configuration on both sides of the watercraft, the
width of the total surface of water involved is equal
to the one comprised in the encumbrance between the two
guards arranged on the opposite sides of the
watercraft.
With specific reference now to the operation of
the system, this envisages, as first step, lowering of
the absorbent material in bulk form into the channel,
after tufting thereof has been carried out by the
tufting units 17. As a result of the advance of the
watercraft, said material traverses the entire channel
until it is brought up to the conveying surface, and
whilst said material is in the channel, the action of
the rotating rolls causes it to be impregnated
completely by the pollutant. Once the material has
reached the conveying surface, this gathers it and
delivers it onto the conveyor belt 22, which carries it
up to the rolls 24, where it is squeezed and separated
from the pollutant, which is collected in the tank 19
whilst said absorbent material is brought back via the
belt 27 to the lowering means 16. From the foregoing it
is evident that the system described herein is designed
to provide a continuous cycle in which the absorbent
material is cast into the channel, gathered, squeezed,
and then cast back into the channel again; this process
can be repeated a number of times until the material
has exhausted its absorbent capacity.
Alternative embodiments can in any case envisage
discharge of the absorbent material gathered by the
channel 8 directly into the tank 19, and hence not
envisage the aforesaid closed cycle so that in said
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embodiments the means referred to above, such as the
squeezing rolls 24, the conveyor belts 15 and 27, etc.,
designed for providing said closed cycle, may thus be
omitted. The system
described = herein preferably
envisages means for controlling the operation described
above in an automatic or semi-automatic way. In
particular, said means have the function of controlling
the speed of the watercraft and the rate of flow of
material that is cast into the channel in a co-
-ordinated way, according to the required operating
conditions. Said means can envisage an interface, via
which it is possible to select or set the various
combinations. For instance, in the case of thick
patches of pollutant it will be necessary to set low
cruising speeds and provide large amounts of absorbent
material.
Illustrated hereinafter is an example of
intervention that can be implemented with the system
described above on a patch of petroleum .having a
thickness of 2 mm. In the case of a watercraft equipped
according to what is illustrated in Figures 1 and 2,
which has a width of approximately 8 m on the level of
the water and presents channels with 50 m long and 2 m
wide, at the speed of 7 km/h, a surface of 0.5 km2 is
depolluted every six hours, with a use of 10.5 tonnes
of greasy wool (re-used for 10 consecutive cycles),
with the production of 31.5 tonnes of exhausted wool
containing 21 tonnes of residual petroleum, and with
recovery of 950 tonnes of petroleum (equal to
approximately 6350 barrels).
It should be noted that the use in said system of
the wool referred to above, thanks to the large
capacity of absorption that this possesses, enables
total removal of the pollutant in very few passages of
the watercraft on the surface of polluted water, and in
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certain cases even in just one passage.
Finally, it may be noted that in the use of said
wool as absorbent material for the system of Figure 2,
the wool can be re-used (i.e., squeezed and
subsequently lowered again into the sea) as many as
about 10 times. In this case, the exhausted wool (i.e.,
after 10 cycles of use) possesses a calorific power of
27.8 MJ/kg, namely, more than 2000 times the calorific
power of normal waste, and almost twice that of dry
wood. The exhausted wool can then, for example, be
'advantageously used in an incineration system.
SYSTEM FOR INTERVENTIONS IN CONFINED BODIES OF
WATER
In general, the system described herein
constitutes an accessory means, with which, for
example, port authorities or other organizations that
operate in coastal areas can be equipped, and which can
be easily transported by means of lorries, or the like,
and operate, where intervention thereof is required,
also from the land, and in restricted spaces, for
instance on the mooring wharfs of ports.
In general, said system comprises:
- a supporting structure;
- a tank carried by the supporting structure;
- a suction device designed to draw in liquid from
the body of water and to pour it into the aforesaid
tank;
- a line for conveying absorbent material, mounted
on said supporting structure and designed to cause said
absorbent material to advance along a closed path of
advance, said conveying line. having a branch that
traverses at least part of said tank so as to immerse
said absorbent material at least partially in said
liquid poured into said tank; and
- means carried by said supporting structure and
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arranged on said conveying line, which are designed to
squeeze said layer of absorbent material on said
conveying line, after it has passed beyond said tank.
In various embodiments, as in the one illustrated
in Figures 5 and 6, the supporting structure referred
to above, designated in the figures by the reference
number 68, is constituted by a container, for example
an ISO container, which is the type of container most
widely available on the market in so far as it is used
for conveying freight both on land and at sea.
Fixed within said container is the tank referred
to above, designated in the figures by the reference
-number 42. Said tank is preferably divided into a first
section 44, sent into which, as will be seen more
clearly hereinafter, is the liquid drawn in by the
suction device, and a second section 46, where the
absorbent material acts. Said tank is thus divided by a
divisory wall 48 designed to enable overflow of liquid
from the first section to the second section.
With specific reference to Figure 5, the absorbent
material is in the form of a web M closed in a loop
characterized by a given thickness (which varies
according to the type of use for which it is designed).
In preferred embodiments, the web M is formed by a
containment mesh shaped like a bag, which is filled
with the absorbent material and subsequently closed in
a loop in the way illustrated in the figures.
Said web is made to turn on itself along a pre-set
closed line of advance via purposely provided conveying
means. In particular, said means are designed to create
a line of advance that traverses the section 46 in such
a way that the web M, during its passage into said
section, comes to be partially immersed in the liquid
contained therein. In various embodiments, as in the
one illustrated, said means comprise rolls that can be
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driven in rotation, which are suitably arranged with
respect to one another to constitute the aforesaid line
of advance. Said line of advance can in any case also
be obtained by any other means suited for the purposes
mentioned.
In various embodiments, as in the one illustrated,
the line of advance (and hence the web M) surrounds the
tank completely; in particular, with reference to the
figures, said line turns around the tank in
longitudinal planes of section, in which both of the
sections 44 and 46 of the tank are located.
Located downstream of the tank (i.e., downstream
with reference to the direction of advance of the web
M) is a set of squeezing cylinders 48 designed to
. squeeze the web after this has emerged from the section
46 in order. to separate and collect the pollutant that
has been absorbed thereby in said section. The liquid
squeezed is collected in a tray 52 underlying the set
of rolls 78 and, via a pump 54 connected to said tray,
is then sent to a cistern (not illustrated). In various
embodiments, as in the one illustrated, the ensemble
formed by the set of rolls 78, the tray 52, and the
pump 54 is set up against the end of the tank close to
the section 44, where, as will be seen hereinafter,
also the means that make up the aforesaid suction
device are located. Fixed, instead, on the opposite end
of the tank is a discharge pipe 62 that communicates
with the bottom portion of the tank and has the
function of discharging the water contained therein, as
will be seen hereinafter.
With reference now to the suction device referred
to above, it has a suction hose 56 supported by buoys
(not illustrated) and connected, via a flexible pipe
57, to a suction pump 58, which, via a delivery pipe
60, is designed to send the liquid drawn in ' by the
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suction hose to the section 44 of the tank. It should
be noted that the suction hose has the function of
drawing in the liquid present on the surface of the
water. Said liquid will comprise a fraction of water
and a fraction of hydrocarbon substance, in variable
amounts according to the thickness and the more or less
uniform distribution of the patch of pollutant that
floats on the surface of the water. The pump is
preferably a dual-stage rotary-vane pump in order to
limit as much as possible mixing of the water with the
hydrocarbon substance drawn in.
With reference now to the operation of the system
described above, it envisages intake of the liquid on =
the surface of polluted water via the suction hose,
which is kept on the surface of the water bV the buoys
associated thereto. The liquid taken in by the suction
hose is then sent, via the pump 58, to the section 44
of the tank, from which, by overflowing, it pours into
the section 46. Thanks to the laminar flow that is
generated, overflowing brings about a separation
between water and pollutant that enables a free surface
to be obtained, practically consisting only of said
pollutant with the water underneath. The pollutant is
absorbed by the web of absorbent material and, via
squeezing thereof, is separated and gathered in the
tray 52, and then sent by the pump 54 to a storage
cistern (not illustrated). The water that accumulates
underneath the pollutant is, instead, discharged into
the sea through the pipe 62.
It may be noted that the system described herein,
with the use of a mattress of wool of the length of
m, is able to separate approximately 20,000 1 of
hydrocarbon substance before having to be replaced.
In general, the system described herein, for
removal of a pollutant floating on a body of water, in
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particular petroleum and/or its derivatives, comprises:
- a supporting structure (68);
- a tank carried by the supporting structure (42);
- a suction device (56, 57, 58, 60), designed to
draw in liquid from the body of water and to pour it
into the aforesaid tank;
- a line for conveying absorbent material, mounted
on said supporting structure and designed to cause said
absorbent material to advance along a closed line, said
conveying line having a branch that traverses at least
part of said tank so as to dip at least partially said
absorbent material in said liquid poured into said
tank; and
- means (48) carried by said supporting structure
and arranged in an area corresponding to said conveying
line, which are designed to squeeze the absorbent
material on said conveying line after it has passed
beyond said tank.
In various embodiments, the aforesaid conveying
line comprises a web M of .absorbent material, and
.conveying means designed to get said. web to turn along
the aforesaid closed line.
In various embodiments, the aforesaid tank is
divided into a first section (44), into which the
liquid taken in by the suction device is sent, and a
second section (46), where said absorbent material
passes in the condition where it is at least partially
immersed, said tank being divided into said first and
second sections by a divisory wall designed to enable
overflow of liquid from the first section to the second
section.
In various embodiments, the aforesaid supporting
structure is constituted by a container (68).
In various embodiments, the aforesaid means for
squeezing said absorbent material comprise a unit with
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squeezing rolls that is traversed by the aforesaid
closed line.
In various embodiments, the aforesaid suction
device has a suction hose (1), which is supported by
buoys and connected, via a flexible pipe (57), to a
suction pump (58) designed to send the liquid taken in
by the suction hose to said tank (42). In various
preferred embodiments, the aforesaid pump a rotary-
vane pump.
In various embodiments, the aforesaid closed line
surrounds said tank (42).
Of course, without prejudice to the principle of
the invention, the details of construction of the
embodiments may vary, even significantly, with respect
to what has been described purely by way of non-
limiting example herein, without thereby departing from
the scope of the invention as defined by the ensuing
dlaims.
