BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a transport tank to be
transported with containing a cargo in a transport inner bag,
and more specifically, a transport tank having a pressure inner
bag for preventing the transport inner bag from moving in a tank
body of the transport tank during transportation, and
transporting method thereof.
2. DESCRIPTION OF THE PRIOR ARTS
In cargo transportation by sea, railroad, road and so forth,
a tank container is generally used for liquid materials (cargo).
As the tank container, a 20 foot container (hereinafter referred
to as a tank container) which conforms to the ISO Standards is
ordinarily used, for example. The tank container has 20 foot
length, 8 foot width, and 8 foot height, so that about 20 tons
of liquid can be filled therein.
In the container transportation to use this kind of tank
container, it is necessary to wash the inside of the tank after
transportation, and in addition, to produce the tank by using
a high quality stainless steel plate with chemical resistance.
In order to solve the problems, Japanese Patent Laid-Open
Publication No. S61-104983 discloses that an inner bag or liner
bag made of soft synthetic resin to have the chemical resistance
is loaded in the tank produced from the general steel plate.
In addition, Japanese Patent Laid-Open Publication
No.2001-354292, Japanese Utility-Model Laid-Open Publication
No.S61-48190, Japanese Patent Laid-Open Publication
No.S50-4615, and Japanese Utility-Model Laid-Open Publication
No.S57-46492 also disclose to load the inner bag in the tank
in order to save the trouble for washing the inside of the tank.
However, with respect to the prior art inner bag to be used
in the tanks and tank containers, it is so difficult to produce
appropriate inner bags for large tanks including the 20 foot
container that there has no practical application. Namely, it
has been difficult to produce the inner bag fitting in the
cylindrical 20 foot container easily and affordably. The ideal
inner bag to fit within the tank container properly would be
a cylindrical-shaped inner bag having approximately the same
shape as the tank container. However, it is necessary to prepare
circular lid films, and in addition, to weld the circular lid
films on both ends of a tubular film. To make matters worse,
since the circular lid film has to be welded not in a
two-dimensional direction, but in a three-dimensional direction,
the exclusive guide apparatus for welding the circular lid film
is required.
In contrast, an envelope type inner bag is easily produced
only by welding the both ends of the tubular film. This type
of inner bag prevents the liquid from directly contacting with
the inside of the tank by joining supply-discharge openings of
the inner bag and the tank. Therefore, changing the inner bag
makes it unnecessary to wash the inside of the tank.
However, the following problem occurs in process of
developing the above-mentioned inner bag. The inner bag may
move during transportation and the movement varies depending
on whether the inner bag is in an approximately fully loaded
condition where an amount of the cargo reaches the transport
tank volume or it is in a non-fully loaded condition. Namely,
if the tank is transported in the non-fully loaded condition,
the cargo moves in the inner bag, and at the same time, the inner
bag moves in the tank. Consequently, the inner bag may be
ruptured, the supply-discharge opening may crack, or the cargo
may not be discharged due to twist or inversion of the inner
bag. Accordingly, some kind of measure has been required.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a transport
tank in which a transport inner bag hardly moves if the transport
tank is transported with the transport inner bag which is not
fully loaded with a cargo, and a transporting method thereof.
In order to achieve the above object, at least one second
inner bag is disposed between a first inner bag containing a
cargo and an inner surface of the tank body. The second inner
bag will expand by filling of filler for holding the cargo to
prevent the first inner bag from moving in said tank body during
transportation.
According to the preferred embodiment of the present
invention, the first and second inner bags are made from a
synthetic resin. The cargo is any of gasses, liquids, and powder
and granular materials, which is put into the first inner bag
after or while pre-filling the filler in the second inner bag.
Although the size of the second inner bag adapts to the amount
of the cargo, if the second inner bag has the approximately same
size as the tank body, it expands when the cargo is discharged
from the first inner bag.
According to the present invention, the second inner bag
will expand by the filler to prevent the first inner bag from
moving in the tank body during transportation, so that it is
possible to settle such drawbacks as the breakage of the first
inner bag due to the movement or the discharge failure of the
cargo due to twist or inversion of the cargo during the
transportation of the first inner bag which is not fully loaded
with the cargo. In addition, a specific amount of the filler
is preliminarily filled in the second inner bag to arrange the
shape of the second inner bag before or while containing the
cargo in the first inner bag, so that the folded second inner
bag is not sandwiched between the first inner bag and the inner
surface of the tank body when the cargo is put into the first
inner bag. Therefore, it is possible to prevent the filling
failure due to the sandwiched portion at the time of filling
the filler in the second inner bag or to prevent the second inner
bag from being ruptured.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other subjects and advantages of the present
invention will become apparent from the following detailed
description of the preferred embodiments when read in association
with the accompanying drawings, which are given by way of
illustration only and thus are not limiting the present invention.
In the drawings, like reference numerals designate like or
corresponding parts throughout the several views, and wherein:
FIG. 1 is a front view of a tank container having a transport
tank to which the present invention is applied; FIG.2A is an explanatory view of the size of a transport
inner bag fitting in a tank body of the transport tank, wherein
a plan view of the tank body and the transport inner bag is shown; FIG. 2B is an explanatory view of the size of the transport
inner bag fitting in the tank body, wherein a longitudinal cross-sectional
surface of the tank body in a longitudinal direction
is shown; FIG. 2C is an explanatory view of the size of the transport
inner bag fitting in the tank body, wherein a longitudinal cross-sectional
surface of the tank body in a width direction is shown; FIGS.3A, 3B, 3C and 3D are schematic perspective views
showing procedure for producing the transport inner bag; FIG.4 is a plan view of a pressure inner bag; FIG. 5 is across-sectionalview, partly in section, showing
a filler supply-discharge opening, a connector and a connecting
hose of the pressure inner bag; FIG.6 is a flow chart showing the procedure for producing
the transport inner bag; FIG. 7 is an explanatory view showing procedure for welding
an inner bag supply-discharge opening; FIG.8 is a cross-sectional view showing a state where an
inner bag supply-discharge opening is attached to a tank
supply-discharge opening; FIG.9A is a perspective view showing process for welding
one end of a tubular film; FIG.9B is a perspective view showing process for venting
air from the tubular film; FIG.9C is a perspective view showing process for welding
the other end of the tubular film after the air venting; FIG.10A is an enlarged plan view showing a welding line
of the inner bag body, wherein the inner and outer tubular films
are thermally welded all together into four layer; FIG.10B is an enlarged plan view showing the welding line
of the inner bag body, wherein the inner and outer tubular films
are thermally welded all together into four layer after the end
of the inner tubular film have been thermally welded into two
layer; FIG.10C is an enlarged plan view showing the weld line
of the inner bag body, wherein the ends of the inner and outer
tubular films are thermally welded together into two layer; and FIGS.11A, 11B, 11C, 11D and 11E are explanatory views
showing process for folding the transport inner bag to contain
it in a packaging bag.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG.1, a twenty-foot ISO container 10 is constituted
of a tank body 11 and a rectangular parallelepiped frame 12 for
holding the tank body 11. A hatch 13 is formed at the top face
of the tank body 11. The maintenance and filling of liquid are
performed through the hatch 13. At the time of transporting,
a lid 14 is locked by a locking member in order to prevent the
lid 14 covering the hatch 13 from opening. A tank
supply-discharge opening 15 is formed in one end of a lower portion
of the tank body 11. A foot valve 16 is fixed through a flange
15a of the tank supply-discharge opening 15.
A transport inner bag 20 is loaded in a lower portion of
the tank body 11, while a pressure inner bag 19 is loaded in
an upper portion thereof. These inner bags 19, 20 are brought
into the tank body 11 from the hatch 13 by an operating person
to set in the tank body 11. The transport inner bag 20 upswells
in the tank body 11 by pouring the liquid as cargo therein from
the tank supply-discharge opening 15 through the foot valve 16,
so that the transport inner bag 20 operates as a lining to the
tank body 11. In addition, the pressure inner bag 19 is filled
with air supplied through a filling hose 17 and a filler
supply-discharge opening 18, and presses the transport inner
bag 20 against the tank body 11, thus, the transport inner bag
20 hardly moves during transportation. As the transport inner
bag 20 stands still in the tank body 11 against the movement
of the liquid in transporting, the transport inner bag 20 is
not ruptured.
As shown in FIG.2A, the transport inner bag 20 is
constituted of an inner bag body 21 having an envelope shape
and an inner bag supply-discharge opening 22 to be fitted in
the tank supply-discharge opening 15. Since the transport
inner bag 20 is formed to the envelope shape, the inner bag body
21 can be easily formed as shown in FIGS . 3A - 3D. In FIG. 3B,
a tubular film 23 is cut into a predetermined length after being
drawn from a film roll 24 which is the roll of the tubular film
23, and then both end portions 23a and 23b of the tubular film
23 are closed by thermally welding or the like (see FIGS. 9A
and 9C).
In FIG.2A, a longitudinal cross-sectional surface
including a central line CL1 extending in the longitudinal
direction of the tank body 11 (B-B arrowed cross-section) is
referred to as a longitudinal cross-sectional surface in the
longitudinal direction, while a longitudinal cross-sectional
surface including a central line CL2 extending in the width
direction of the tank body 11 (C-C arrowed cross-section) is
referred to as a longitudinal cross-sectional surface in the
width direction. A line CL3 shown in FIG.2B is a central line
extending in a height direction of the tank body 11.
The tank body 11 is formed to a tubular shape whose both
ends are closed to be placed transversally, while the transport
inner bag 20 is formed to the envelope shape. Therefore, if
the transport inner bag 20 is smaller than the appropriate size
corresponding to the size of the tank body 11, a predetermined
filling capacity is not ensured. To make matters worse, the
smaller inner bag creates a gap between the inner peripheral
surface of the tank body 11 and the transport inner bag 20 where
the transport inner bag 20 together with the liquid can move
to damage the welded portion of the inner bag supply-discharge
opening 22 and the welded lines of the both ends of the transport
inner bag 20. Whereas, if the transport inner bag 20 is larger
than the appropriate size corresponding to the size of the tank
body 11, the raw material of the transport inner bag 20 is wasted.
Moreover, if an extra portion such as the end portion of the
transport inner bag 20 is under the liquid filled in the transport
inner bag 20, the extra portion is sandwiched between the inner
bag body 21 filled with the liquid and the peripheral surface
of the tank body 11 due to the weight of the liquid. As a result,
it becomes impossible to fill liquid furthermore. If the liquid
is kept filled while the extra portion is sandwiched, the internal
pressure of the transport inner bag 20 rises to possibly damage
the transport inner bag 20.
In the present embodiment, the size of the envelope type
transport inner bag 20 is limited within a specific range based
on the size of the tank body 11 for the purpose of preventing
the filling failure and the damage of the transport inner bag
20. When the length of the transport inner bag 20 is IL, the
width thereof is IW, the inner peripheral length (first inner
peripheral length) of the tank body 11 in the longitudinal
cross-sectional surface in the longitudinal direction is TLt,
and the inner peripheral length (second inner peripheral length)
of the tank body 11 in the longitudinal cross-sectional surface
in the width direction is TLr, the following conditions are
satisfied:
0.47·TLt ≤ IL ≤ 0.6·TLt;
and
0.47·TLr ≤ IW ≤ 0.6·TLr.
IL and IW preferably satisfy the following conditions:
0.49·TLt ≤ IL ≤ 0.55·TLt;
and
0.49·TLr ≤ IW ≤ 0.58·TLr.
As above-mentioned, the size of the transport inner bag
20 is limited based on the inner peripheral length of the tank
body 11, so that the tank body 11 may have different shapes than
tube such as an elliptical shape or others.
The inner bag supply-discharge opening 22 is provided on
the central line extending in the longitudinal direction at a
position apart from one end of the transport inner bag 20 by
the distance L1=1750mm or adjacent thereto. The distance L1
is limited within a range 0.44·IW ≤ L1 ≤ 0.50·IW based on the
width IW of the transport inner bag 20, so that it is possible
to position the central positions in the longitudinal direction
of the tank body 11 and the transport inner bag 20 with each
other if the transport inner bag 20 is attached to the tank body
11 with reference to the tank supply-discharge opening 15, which
is formed in the end of the lower portion of the tank body 11.
Thereby, the extra portions in both ends of the transport inner
bag 20 can be distributed approximately evenly in the tank body
11. Accordingly, the extra portion of the transport inner bag
20 dose not build up on one side to be sandwiched between the
tank body 11 and the inner bag body 21, so that the filling failure
and the damage of the transport inner bag 20 are eliminated.
As shown in FIG. 4, the pressure inner bag 19 is constituted
of an inner bag body 19a having an envelope shape and a filler
supply-discharge opening 18. Although the pressure inner bag
19 is formed into the envelope shape having the same size as
the transport inner bag 20 shown in FIG.2, since the liquid as
the cargo is not filled in the pressure inner bag 19 unlike the
transport inner bag 20, the pressure inner bag 19 has a
single-layer structure, and in addition, has the filler
supply-discharge opening 18 instead of the inner bag
supply-discharge opening 22.
As shown in FIG.5, the filler supply-discharge opening
18 is constituted of a cylindrical body 18a made of a synthetic
resin. A welding flange portion 18b is formed in an end of the
filler supply-discharge opening 18, while an attachment female
screw 18c is formed in an inner peripheral surface of the other
end. A bottom attachment screw 51a of a hose connector 51 having
a valve 50 is screwed into the filler supply-discharge opening
18 through the attachment female screw 18c. A hose connection
opening 51b and a cap attachment screw 51c are formed above the
hose connector 51.
The hose connection opening 51b uses a snap type connection
to hold the end of the hose removably. The valve 50 is closed
by rotating a handle 50a at the time of removing the filling
hose 17 from the hose connector 51. After removing the filling
hose 17, a cap 52 is fitted in the cap attachment screw 51c.
Note that a screw type of the hose connection opening may be
used instead of the snap type. In addition, with regard to the
shape and structure of the filler supply-discharge opening 18,
the valve 50 and the hose connector 51 and the attaching method
for them, various embodiments may be applied to the present
invention. Moreover, the pressure inner bag 19 may be formed
in a multilayer structure to have two or more layers.
Next, the procedure for producing the transport inner bag
20, which is shown in FIG. 6, is explained. As shown in FIGS.3A
and 3B, the tubular film 23 is drawn from the film roll 24 to
be put on a work table 25, and then cut into the length IL by
a cutter 26 or the like. The tubular film 23 is made from LLDPE
(linear low density polyethylene), and wound into a roll shape
to be stored. Since the transport inner bag 20 is doubled in
the present embodiment, it is necessary to form the two tubular
films 23 by cutting the tubular film 23 twice into the length
IL. The transport inner bag 20 of the present invention is used
for the 20 foot container, so that the first inner peripheral
length TLt = 15500mm, and the second inner peripheral length
TLr ≒ 7100mm, while IL = 8300mm and IW = 3900mm based on the
above-mentioned appropriate size range. The thickness of a
single layer of the tubular film 23 is 120µm. Since the tubular
film 23 of the present embodiment has two layers, the entire
thickness of the tubular film 23 is 240µm. The thickness of
the film is preferably 80 - 500µm, especially 100 - 300µm.
As shown in FIG.3C, in doubling the tubular film 23, one
tubular film is inserted into another tubular film.
Subsequently, as shown in FIG.3D, a hole 27 corresponding to
the inner bag supply-discharge opening 22 is opened on only the
upper two layers of films by a punch or a cutter. The inner
bag supply-discharge opening 22 is located at the center in the
width direction and apart from other end portion 23b by the
distance L1=1750mm.
As shown in FIG.7, when the inner bag supply-discharge
opening 22 is attached to the inner bag body 21, the opening
22 is thermally welded to a peripheral edge of the hole 27. At
this time, only the upper two layers of the films are thermally
welded. The inner bag supply-discharge opening 22 is
constituted of a supply-discharge mouth 22a having a truncated
conical and cylindrical shape, a welding flange 22b and an
attachment flange 22c which are attached to both the ends of
the supply-discharge mouth 22a, and integrally formed by using
LLDPE for example. The welding flange 22b and the inner bag
body 21 are thermally welded by a thermal welding apparatus (not
shown) to form welding lines 28 and 29. As shown in FIG.8, when
the inner bag supply-discharge opening 22 is inserted to the
tank supply-discharge opening 15 from the inside of the tank,
the attachment flange 22c protrudes outside the flange 15a of
the tank supply-discharge opening 15 to be fixed firmly to the
flange 15a.
As shown in FIG.8, an attachment flange 30a of an inner
bag suction preventing member 30 and the foot valve 16 are attached
to the flange 15a of the tank supply-discharge opening 15, so
that the inner bag supply-discharge opening 22 is attached firmly
to the tank supply-discharge opening 15. The supply-discharge
mouth 22a is formed along the inner peripheral surface of the
tank supply-discharge opening 15.
As shown in FIG.9A, in welding the one end portion of the
tubular film 23, all four layers of films in the end portion
23a of the tubular film 23 are thermally welded simultaneously
by the thermally welding apparatus 33 to seal the end portion
23a. The thermally welding apparatus 33 is constituted of a
receiving stage 33a and a welding head 33b. The heat is applied
to the end portion 23a, which is held by the welding head 33b
and the receiving stage 33a after the welding head 33b has been
moved down.
As shown FIGS.10A-C, two stripes of thermal welding lines
35a and 35b of 5 mm in width are formed linearly at an interval
of 5-10mm. Note that one or three or more thermal welding lines
may be formed. In addition, a corrugated thermal welding line
may be applied to the present embodiment instead of the linear
one. If the plural thermal welding lines are formed, all lines
may be formed together, or each line may be formed one by one.
In FIG.10B, a thermal welding line 36a is formed by welding the
one end portion of the inner tubular film 23 into two layer,
and then a thermal welding line 36b is formed by welding the
one end portion of both the inner and outer tubular films 23
into four layer. The thermal welding line 36b is positioned
outside the thermal welding line 36a. In FIG.10C, thermal
welding lines 37a and 37b are formed by welding each end portion
of the tubular film 23 into two layer separately wherein the
inner tubular film is slightly shorter in length than the outer
one. Although the thermal welding line may be welded at a time,
if the length of the welding head 33b is limited, the thermal
welding line may be welded sequentially every length of the
welding head 33b. Note that ultrasonic welding or other welding
method may be applied to the present embodiment instead of the
thermal welding by using the heat-sealing type thermal welding
apparatus 33.
As shown in FIG.9B, a pressing roller 38 is rotated on
the work table 25 from the welded end portion 23a toward the
other end portion 23b to vent air 39 in the doubled tubular film
23. Instead of rotating the pressing roller 38, the air may
be vented by folding the inner bag body 21 from one end side
to the other end side. Since the inner bag supply-discharge
opening 22 is attached close to the other end portion 23b so
as to protrude from the inner bag body 21, the air between the
inner bag supply-discharge opening 22 and the other end portion
23b is vented by using a small roller for avoiding the
supply-discharge opening 22.
As shown in FIG.9C, the other end portion 23b of tubular
film 23, in which the air has been vented, is welded by the thermal
welding apparatus 33 as well as the case of the end portion 23a.
Thereby, the transport inner bag 20 shown in FIG.11A is completed.
A positioning mark 45 is recorded thereon along a central line
extending in the longitudinal direction of the transport inner
bag 20 by using an oil-based ink or the like. The inner bag
body 21 is folded, and then contained in a packaging bag 40 as
shown in FIG.11E. Although the positioning mark 45 is formed
linearly in the present embodiment, the shape or size of the
positioning mark is not limited especially.
As shown in FIG.11A, the inner bag body 21 with the
supply-discharge opening 22 directed downward is folded inward
along inward folding lines 21e in parallel with the positioning
mark 45 so as to make both the side edge portions 21a and 21b
approach the central line. Likewise, as shown in FIG.11B, the
inward-folded portions are folded inward again along inward
folding lines 21f in parallel with the central line extending
in the longitudinal direction so as to make the inward folding
line 21e approach the central line. Thereby, the inner bag body
21 is double folded. Subsequently, as shown in FIG.11C, the
inner bag body 21 is folded plural times along the inward folding
lines 21g toward the inner bag supply-discharge opening 22 from
both the end portions 21c and 21d of the inner bag body 21, so
that the inner bag body 21 is folded into a small size as shown
in FIG.11D. The inner bag body 21 may be rewound from the one
end to be a roll shape instead of being folded inward along the
inward folding lines 21g. After folding the inner bag body
21 into the small size, the transport inner bag 20 is put in
the packaging bag 40 as shown in FIG.11E. Since the inner bag
body 21 is double folded along the inward folding lines 21e and
21f, it can be contained compactly. Note that the inner bag
body 21 may be folded once or three times and above along the
central line extending in the longitudinal direction.
As aforementioned, since the inner bag body 21 is folded
such that the inner bag supply-discharge opening 22 is directed
outside the inner bag body 21, the inner bag supply-discharge
opening 22 can be inserted to the tank supply-discharge opening
15 easily. In addition, the inner bag body 21 is folded inward
along the inward folding lines 21g, so that the inner bag body
21 can be expanded easily in the longitudinal direction of the
tank body 11 in a state that the inner bag supply-discharge opening
22 is set in the tank supply-discharge opening 15. Furthermore,
since the inner bag body 21 is folded inward along each of the
inward folding lines 21e and 21f in a state that the inner bag
supply-discharge opening 22 is directed downward, the inner bag
body 21 is expanded by itself by filling the liquid from the
inner bag supply-discharge opening 22.
Although the pressure inner bag 19 is produced by a
procedure similar to the transport tank 20, the doubling of the
tubular film 23 and the recording of the positioning mark 45
are not required and would be omitted. The filler
supply-discharge opening 18 is attached instead of the inner
bag supply-discharge opening 22. The filler supply-discharge
opening 18 is attached so as to correspond to the position of
the hatch 13 of the tank body 11, so that it becomes possible
to attach and remove the filling hose 17 and also open and close
the valve 50 at the hatch 13.
Next, the method of loading the transport inner bag 20
and the pressure inner bag 19 in the tank body 11 is explained.
First, the inner bags 19, 20 in the packaging bag 40 are brought
into the tank body 11 by the operating person, and then the
transport inner bag 20 is taken out from the packaging bag 40.
The positioning mark 45 is recorded linearly on the transport
inner bag 20 so as to correspond to the central line CL1 extending
in the longitudinal direction of the tank body 11. After the
foot valve 16 has been removed from the flange 15a of the tank
supply-discharge opening 15, the inner bag supply-discharge
opening 22 is inserted in the tank supply-discharge opening 15
so as to conform the positioning mark 45 to the central line
CL1. Thereby, the attachment flange 22c is attached firmly to
the flange 15a. Second, the inner bag body 21 folded along the
inward folding lines 21g is unfolded in the longitudinal
direction of the tank body 11, and then the folded portions along
the inward folding line 21f are unfolded. Both the side edge
portions which are folded along the inward folding lines 21e
are not unfolded. Since the approximately overall width of the
inside of the tank body 11 is covered by the inner bag body 21
of which the both side edge portions are folded along the inward
folding lines 21e, even if the both side edge portions are unfolded,
they are folded again by their weight.
Next, the pressure inner bag 19 is lapped over the unfolded
transport inner bag 20 to be unfolded in the same manner as the
transport inner bag 20. Subsequently, as shown in FIG.5, the
filling hose 17 is connected with the filler supply-discharge
opening 18 of the pressure inner bag 19. As shown in FIG.1,
the filling hose 17 is inserted inside the tank body 11 through
the hatch 13. After that, the operating person goes outside
the tank body 11 from the hatch 13 to finish the loading operation
for the inner bags 19, 20. Then, as shown in FIG.8, the inner
bag suction preventing member 30 and the foot valve 16 are attached
to the tank supply-discharge opening 15 from the outside of the
tank body 11.
The liquid as the cargo is filled from the tank
supply-discharge opening 15. The filling speed is 50 liters
per minute, for example. The inner bag body 21 is extended in
the longitudinal direction in the tank body 11, so that the inner
bag body 21 upswells by filling the liquid in the inner bag body
21 smoothly. The both side edge portions of the inner bag body
21, which are folded inward, are gradually unfolded with the
filling of the liquid, so that the end portions of the inner
bag body 21 are not accidentally caught between the inner bag
body 21 and the tank body 11 by the weight of the portion in
which the liquid is filled. Therefore, the inner bag body 21
upswells smoothly by the filling of the liquid. In the fully
loaded condition, about 20 tons of liquid is contained in the
inner bag body 21; however, the present embodiment premises the
transportation in the non-fully loaded condition, 10 tons of
liquid is contained in the inner bag body 21 for an example of
the non-fully loaded conditions.
The air is put up to 10-20% of the filling capacity, for
example, in the pressure inner bag 19 before or at the same time
as the onset of the liquid filling in the transport inner bag
20. The pre-filling of the pressure inner bag 19 is performed
in order to arrange the shape of the pressure inner bag 19 so
that the pressure inner bag 19 avoids to be sandwiched between
the transport inner bag 20 and the inner surface of the tank
body 11 due to the filling of the liquid. The filling of the
air is temporarily stopped at the time of reaching the pre-filling
amount. After the predetermined transportation amount, 10 tons
of liquid for example, has been flowed in the transport inner
bag 20, the air is filled again in the pressure inner bag 19.
The air is stopped filling after a gap between the inner surface
of the tank body 11 and the transport tank 20 has been filled
by the air. The filling hose 17 is removed after closing the
valve 50, and the cap 52 is placed on the filler supply-discharge
opening 18. After that, the hatch 13 is closed, and then the
filling operation for the tank body 11 is finished. Note that
the air to be preliminarily filled in the pressure inner bag
19 may be equal to or slightly exceed the capacity which subtracts
the predetermined transportation amount from the capacity of
the tank body 11 before the liquid filling in the transport inner
bag 20. If the air is preliminarily filled in the pressure inner
bag 19 to slightly exceed the above-mentioned capacity, the
liquid is filled in a state that the valve 50 is slightly open
to discharge the extra air in the pressure inner bag 19 while
the liquid is filled in the transport inner bag 20. Thereby,
it is possible to alleviate or eliminate the air filling operation
in the place for the liquid filling. Note that an air vent valve
such as a one-way valve may be provided instead of or in addition
to the valve 50.
In the present embodiment, the inner bag body 21 is loaded
in the tank body 11 to extend in the longitudinal direction,
and its side edge portions are folded inward toward the central
line extending in the width direction of the inner bag body 21.
That prevents the air from entering the inner bag body 21 and
the inner bag body 21 can be used for the anaerobic liquid. In
addition, since the inner bag body 21 and the inner bag
supply-discharge opening 22 are made from LLDPE having high
chemical resistance, the tank body 11 has more choices in material.
Furthermore, it is unnecessary to line the inner peripheral
surface of the tank body 11 with fluorocarbon resin such as
polytetrafluoroethylene.
When the inner bag body 21 dwindles to close with the inner
bag supply-discharge opening 22 after the remaining amount of
the liquid is reduced, the inner bag body 21 may be accidentally
sucked into the inner bag supply-discharge opening 22 to cover
the opening 22. In order to prevent the inner bag body 21 from
covering the inner bag supply-discharge opening 22 in discharging
the liquid from the tank supply-discharge opening 15, when the
liquid is discharged from the tank supply-discharge opening 15,
a passage between the inner bag body 21 and the inner bag
supply-discharge opening 22 is ensured by the inner bag suction
preventing member 30. The inner bag suction preventing member
30 is integrally constituted of a semi-spherical end 30b arranged
to protrude toward the inside of the tank body 11, a tubular
portion 30d whose peripheral surface has plural continuous holes
30c, and the attachment flange 30a provided on the base of the
tubular portion 30d. The semi-spherical end 30b protrudes
toward the inside of the inner bag body 21, so that the residual
liquid in the inner bag body 21 can be surely discharged through
the continuous holes 30c without the inner bag body 21 stick
to the inner bag supply-discharge opening 22.
In the above embodiment, the inner bags 19, 20 are made from
LLDPE, they may be made from LDPE (low-density polyethylene),
OP (biaxially oriented polypropylene) and other synthetic resin.
In addition, although the inner bag body 21 is doubled in the
present embodiment, it may have a multilayer or single-layer
structure. Moreover, the tank body 11 may have different shapes
than tube such as an elliptical shape or others. Furthermore,
the inner bags 19, 20 may be used not only for the tank container,
but also for a tanker lorry and so forth. The present invention
is not limited only to the inner bag having an envelope shape
in the above embodiment, but is also applicable to a cylindrical
shape or other shapes.
In the above embodiment, although the pressure inner bag
19 has the same size as the transport inner bag 20 capable of
carrying 1-19 tons of cargo in the non-fully loaded condition,
the pressure inner bags may be provided with, for example, four
sizes accommodating to 1-5 tons, 5-10 tons, 10-15 tons and 15-19
tons of cargo in accordance with the transportation amount.
Thereby, the pressure inner bag 19 the size of which is
unnecessarily large is not required, so that it is possible to
prevent the material thereof from being wasted. In addition,
not only one pressure inner bag but plural ones may be used in
the present invention. In this case, plural filling hoses are
connected to each inner pressure bag 19 when the liquid as the
cargo is filled.
The pressure inner bag 19 and the transport inner bag 20
may be folded together in a state that the pressure inner bag
19 is lapped over the transport inner bag 20 not as loading these
inner bags separately. Thereby, the folding and the loading
of the inner bag can be performed at a time, so that the operation
time is reduced in comparison with the case in which these
operations are performed separately. When folding together,
the portions of these inner bags may be temporally attached each
other by a two-sided adhesive tape.
The air is used as the filler in the above embodiment;
however, gas emission from a track engine or inert gas such as
nitrogen gas may be used. In addition, the air may be filled
by connecting a cartridge directly instead of using the filling
hose. Moreover, not only gasses but also liquids such as water
or powder and granular materials made of a synthetic resin foam
may be used as the filler. Furthermore, the cargo is not limited
to only the liquids, but powdery or granular cargo may be applied
to the present embodiment.
Note that the back pressure may be applied to the cargo
by expanding the pressure inner bag, which has the approximately
same capacity as the tank body, when the cargo is discharged
from the tank body. Thereby, the cargo having high viscosity
can be discharged smoothly and rapidly.
Although the present invention has been fully described
by the way of the preferred embodiments thereof with reference
to the accompanying drawings, various changes and modifications
will be apparent to those having skill in this field. Therefore,
unless otherwise these changes and modifications depart from
the scope of the present invention, they should be construed
as included therein.