Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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A METHOD OF REMOVING OIL OR SIMILAR LIQUIDS FROM THE SURFACE OF
WATER OR A SOLID MATERIAL.
The present invention relates to a method of removing oil or
similar liquids from the surface of water or a solid material,
and to its reyeneration.
It is an object of the present invention to provide a new method
which, in case of a leak, makes the oil removal possible,
especially to a tanker by its own crew; or similar oil
prevention actions.
Most of the oil accidents on the water areas happen so that a
tanker springs a leak and a limited amount of oil runs into the
water. Relatively seldom the leak is so large that whole of the
tanker runs empty, although this is really very disastrous. The
major part of the oil damages is thus to be prevented, if the
tanker itself has been provided with the proper prevention
equipment and material and the prevention acts can be started
immediately during the first minutes of the accident.
The process of the preventive actions are as follows:
When the oil leak has happened the leakage area is surrounded
by e.g. boom nets in order to master the spreading of the oil
and in order to be able to carry out the preventive actions.
Granulated glass wool is spread by e.g. a blower over the area
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surrounded by the booms. The material, into which the oil is
absorbed and which gathers towards -the booms, forms kind of
miniature mountains, the tops of which go under the surface of
the water.
This combination of the boom and the granulated glass wool
forms a protective structure which prevents the further
spreading of oil, even when -the sea is rough. From the area
limited by the booms, it is possible to lift the oily wool
back to the vessel with e.g. a grab bucket fixed to a hydraulic
crane boom, or with a nylon net. The catch is emptied into a
funnel leading it into a centrifuge or on to a suction wire.
After the centrifugalizing or the suction process, where the oil
is separated by means of centrifugal force or suction air from
the granulated mineral wool, the oil is lead to a separate
container, which can be either a big, floating "sock" made of
rubber or some other container. The granulated wool can be e.g.
~blown or otherwise conveyed to the surface of the sea for a new
recovery process. This can be repeated over and over again. Thus
it is possible to master a limited leakage with this method
until the leakage is stopped or the whole bunker in the vessel
is emptied to the sea level and other actions to save the
situation have been organized.
It is already known to use mineral wool to absorb and to retain
oil from the surface of the water (the Finnish Patent No 43289,
the US Patent No 3,933,632 and the British Patent No 1 235 463),
both glass wool and rock wool. The great capacity of the mineral
wool to absorb oil has been demonstrated in these methods.
In these methods the used mineral wool has been regarded as a
non-recurrent material, which is burned together with the oil
absorbed in it. When the material is burned, the binding
material on the fibre is destroyed and the material loses its
good absorbtive and floating qualities. The binding material is
a very important factor as to the absorbtion process. To coat
the burned fibre anew is very labourous and in the field work
of the oil prevention practically impossible, as the covering
requires, amon~ other things, an accurate heat treatment. The
coal which remains on the fibre after the burning i5 not good
enough as to its absorbtive qualities, and furthermore, it can
be washed away.
When the mineral wool is used as a non-recurrent material there
are no specific requirements as to its oil retaining capasity.
One has been satisfied with the absorbtive or absorbent
capacity, which is inherent in most mineral wool materials. With
the oil retaining capacity it is thus meant its ability to
retain oil in itself when lifted up in the air. This property is
essential in the method, where granulated glass wool is used as
~a "transfer vessel", when the oil is removed from the water to
the tanker. The retaining of the oil, on the other hand, must
not be excessive, as in some well known methods, where heavy
metals are added to the fibre structure of the mineral wool in
order to improve the absorbtion and retaining capacities. By so
doing the material looses most of its floating capacity and thus
makes it difficult to remove the oil by other methods than by
burning. It is known, as well, that mineral wool whose volume
weight is relatively small, absorbs more oil in comparison to
its weight than a heavier wool, but, correspondingly, the
retaining capacities decrease so much that this prevents the
transference o~ oil from one place to another, as the material
acts lika a leaking "transfer vessel". The use of non-recurrent
material in the vessel presupposes a very large storage of
mineral wool, and this is why its use as a preventive material
has not reached the level which its properties imply.
The present invention is based on the discovery that one
particular glass wool material in the form of granulated glass
wool possesses such an inner structure - after having been made
of a proper glass wool blank~bound with plastic resin and heat-
treated - that it has a notable capacity of retaining oil and
that it is possible to remove oil mechanically out of the
structure by using earlier known methods such as suction and
centrifugalizing so that both the structure of the glass wool
is preserved as well as the resin on the fibres after the oil
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removal treatment. This makes it possible to use the same glass
wool material repeatedly, and, consequently there is needed
only a limited storage of glass wool on e.g. a tanker, which,
further, makes it possible for the crew itself to carry out
the prevention actions with proper equipment.
It is a characteristic feature of the method according to the
invention that by using the already known method of suction or
centrifugalizing it is possible to remove and to recover at
least 90 ~ of the oil absorbed in the granulated wool providing
that the degree of absorbtion into the wool is adequate. It has
been proved by experiments that by squeezing the oil out it is
impossible to remove the same quantity of oil without breaking
the structure.
It is a characteristic feature of the granulated mineral wool
used in this method that after the described oil removal it can
abosorb essentially the same quantity of oil as the removed one
once again.
A characteristic feature of the granulated wool used in this
method is also the fact that the oil is absorbed from the
surface of the sea to the free spaces in between the fibres
and that when the wool is lifted from the see permitting it to
drain for one minute, the major part or at least 60 ~ of the
absorbed oil remains in it.
A characteristic feature of the granulated wool used in this
method is also that a limited amount of moisture in the wool
does not essentially impair its utilization in this method.
A characteristic feature of the granulated wool used in this
method is also that the absorbed oil does not significantly
flow away with the slow passing through of the water caused by
the rough sea.
It has been discovered that the best material for this purpose
is granulated wool which consists of minor, one-size mineral
wool pieces, and where the amount of loose fibres is small. The
average diameter of -the fibres must be from 3 to 2~um. There
should not notably be so called pearls. The volume weight of
the granulated woo1 should preferably be from 40 to 120 kg/m3
and most suitably from 70 to 110 kg/m3. The fibres must be
coated with plastic resin, which, at the same time, bonds the
fibres together. The granulate is made by cutting a mineral wool
blank in pieces.
A characteristic feature of the granules of the described
material is their elasticity which arouses from the homogenity
of the structure and whicH makes it possible that it including
the coating material can endure mechanical treatment such as
lifting out of the water by drug bucket, net or the like;
centrifugalizing, suction or blowing by a fan or some other kind
of spreading it out without being damaged.
It has been proved by experiments that the granulate used in the
method blown on the surface of the water will float on the water
at least 6 months and that the portion sinking is appr. 1 ~.
It has also been proved experimentally that the properties of the
granulate used in the method are not essentially impaired after
having been stored even for several years tightly packed.
.~thou~h, in the described embodiments of the invention, the
material used has been glass wool it does not range out the
possibility of using other mineral wools as well, if only their
properties meet the requirements of the method. Although in the
described embodiment oil is removed from the surface of the water
back to the tanker, from where the leakage has taken place, the
method of the invention is not restricted to this application
but can also be used in other kinds of vessels, especially in
vessels built for oil removal purposes. In this latter case it
is possible to use a wire sunk into the water as an oil
collecting means. It can also be used on harbour docks and
equipments, in oil recovery actions taken from the ice or any
other firm base or for removal of oil from diches and pits, etc.
. . . . . . . .
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The method accordinc3 to the invention can also be used for
removal of other liquids similar to oil, such as: combustible
oils, kerosene, metanol, alcohols, solvents and paints.
Examples:
1. The capasity of absorbtion and of retention was measured
with the equipment which consisted of an absorbtion vessel of
6.8 litres furnished with a bottom with holes having the
diameter of 260 mm and of an oil container having a diameter
of 300 mm. Granulate of glass wool of various volume weights
were placed in the absorbtion vessel which was placed into
the oil container. After the absorbtion the bottom tap of the
oil container was opened and the amount of the absorbed oil
was measured. The absorbtion vessel was lifted out of the
container and the oil was allowed to drain during one minute
of time, after which the oil retained by the wool was
measured. The used oil was commercial diesel fuel. The
experimental temperature was + 20 C.
The results of are presented in the table below:
Test Volume Weighed Absorbed Retained Absorbed Retained Retention~
weight granulate l of o/ l of o/ of
kg/m3 (g) ml ml kg of g kg of g absorbtion
1 120 816 5930 45807.2 5.6 78
2 100 680 6280 52409.2 7.7 84
! 3 62 422 5930 471014.0 11.2 80
4 52 354 6100 425017.2 12.0 70
136 4750 237034.9 17.4 50
-
l of o = litres of oil
kg of g = kilogrammes of granulates
/
2. A centrifugalizing experiment was carried out by using a
washing machine, whose rotational speed was 2700 r/min, the
centrifugaliz-ing time was one minute, the temperature was
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+ 20 C. The oil used was diesel fuel and as absorbtion
material granulated glass wool having a volume weight of
48 kg/m3 was used.
Test 1.
Phases Weight of Retained Retained Centri- Separated Oil re- Separate~
original oil + oil fugalized . oil mained oil of
granulate granulate granulate in retained
granulate
(g) ~g) (g) (g) (g) (g) (g~ ,
1 500 3803 3303 612 3191 112 97
2 612 3580 3080 603 2977 103 97
3 603 3419 2919 602 2817 102 97
4 602 3386 2886 611 2775 111 96
Test 2.
. .
1 500 3800 3300 607 3193 107 97
2 607 3607 3107 607 3000 107 97
3 607 3607 3107 615 2992 115 96
4 615 3615 3115 603 3012 103 97
603 3603 3103 605 2998 105 97
6 605 3605 3105 602 3003 102 97
'
'3. The use of moist wool in absorbtion and its floating capacityl.
The experiment was carried out in the laboratory for the
combustible and lubrication materials of the Technical
Research Institute of Finland in Espoo, on the 7th of April,
1978. The volume weight was defined by weighing and by
measuring and with the method of Klein & Ander. The
percentage of the moisture was defined according to DIN 51718.
The oil retention capacity was defined by the method of
Sturz & Klein. The experimental temperature was + 20 C and
the oil diesel fuel.
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Results:
Samp]e Volume Moisture Volume Oil retention Floatiny
weight weight of capacity capacity
dxy substance 1 of oil/ 1 h after the
kg/m3 % kg/m3 ky of granu mLx g
1 59.2 0.4 59.0 10.5 > 99
2 59.7 0.72 59.0 10.9 > 99
3 93.6 23.7 71.4 5.87 > 99
4. 10,3 g of granulated glass wool in which 49,8 g of crude oil
had been retained was placed in a glass tube having a
diameter of 40 mm and a height of 300 mm. 10 l of water was
poured through the tube with a speed of 5 l/h. The separated
quantity of oil was 3.6 g or 6 % of the retained oil,
5. Suction tests were carried out by using a vessel with a
screen bottom, in which a vacuum of 900 mm water was
maintained. Tho volume weight of the granulate was 48 kg/m3
and diesel fuel was used as oil, the temperature was + 20 C.
; The suction time was 1 min.
1.
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Pllases Weight of Retained Retained ~7eight of Sepa- Oil Separated/
; original oil + oil granulate rated retained retained
granulate granulate aft suction ~oil in the
treatment granulate
(g) (g) (g) (g) (g) (g)
Test 1.
1 80 503 423 178 325 9876.8,
2 178 480 302 175 305 -3 100
3 175 461 286 186 275 11 96
4 186 457 271 179 278 -7102.5
Test 2.
1 60 404 344 146 258 86 75
2 146 385 239 139 246 -7 103
3 l39 382 243 135 247 -4 102
4 135 368 233 136 232 1100
Test 3.
1 40 269 229 81 188 41 82
2 81 268 187 81 187 - 100
3 81 256 175 81 175 - 100
4 81 246 165 80 166 -1 100
