CN112789229A

CN112789229A - Flexible tank for container

Info

Publication number: CN112789229A
Application number: CN201980044600.9A
Authority: CN
Inventors: R·古斯; D·波斯泰克
Original assignee: Odyssey Logistics & Technology Corp
Current assignee: Odyssey Logistics & Technology Corp
Priority date: 2018-06-30
Filing date: 2019-08-30
Publication date: 2021-05-11
Also published as: US20210362942A1; EP3814248A4; CA3105181A1; WO2020006582A3; EP3814248A2; SG11202013109TA; WO2020006582A2

Abstract

A flexible tank for transporting bulk liquid or semi-liquid material in a transport container on a railway vehicle. It has an inner reservoir and at least one end cap with alternating hollow rings from two separate outer layers. Nylon rope or similar securing means which passes through the hollow ring to restrain the inner tank with an outer layer at the end cap. An end flap may be welded to the outer layer and positioned between the inner tank and the end cap. The hollow loops may be formed by folding the outer layer and cutting out complementary portions so that the loops are in an alternating staggered pattern. The volume band located around the flexible tank limits the expansion of the flexible tank at its respective location.

Description

Flexible tank for container

Background

This lengthy cargo transportation often involves multiple modes of transportation, such as ocean going vessels, rail cars, and trucks. Standardized intermodal containers facilitate intermodal transportation in that they allow various cargo to be easily transported back and forth between ports and warehouses, as well as between ships and rail cars. Some organizations, such as the international organization for standardization (ISO), have established and continued to maintain standards for shipping containers, such as dimensions, door locations, and the use of specific corners or fittings so that the containers can be securely grasped and moved by the lifting devices. The ability to use standardized shipping containers is an advantage because the logistics of container handling equipment and the handling of special cargo is simplified when no special custom shipping containers are needed. For example, large quantities of liquid (which may also be used to transport dry cargo) may be transported by placing the liquid in a flexible tank of a transport container, and then the container may preferably be handled like other transport containers, regardless of the nature of its contents.

There are special devices for transporting bulk liquid products by road, rail and ship. However, it is desirable to achieve cost savings using standard container equipment. Standardized shipping containers are common in both national and international trade routes and are therefore cheaper to use. For example, 40 'or 53' containers are readily available in north america. In some intermodal routes, such large transport containers are ubiquitous, and so it may be economically beneficial to use flexible tanks therein having the same capacity as the smaller 20' transport containers.

These large containers have a much larger internal volume than the smaller 20' shipping containers. It may be difficult to fully utilize the large internal volume due to weight limitations. The specific gravity (weight per gallon) of the liquid to be transported can vary widely and the volume of liquid that can be transported within weight limits varies accordingly. Conventional flexible tanks are typically mass produced and are single-capacity. This is disadvantageous for large transport containers with a high internal volume, since in large transport containers it is more likely that different volumes of liquid need to be transported, keeping the weight limit. Other disadvantages of large transport containers must also be addressed when transporting liquids.

For example, a 40 foot long container may not always be convenient for use of a bulkhead. Flexible tanks designed for 20 foot containers with baffles are typically longer than the interior length of the container so that the ends of the flexible tank are supported by the baffles placed across the front interior wall and the door opening of the rear wall of the container. Thus, a flexible tank within a 20 foot shipping container may be, for example, 23 feet long. A 40 foot shipping container may not facilitate the use of bulkheads and front walls, and therefore the flexible tank must be freestanding without relying on the availability of any end walls or bulkhead supports.

The flexible tank does not deform either the side or end walls of the container in which it is placed. Sometimes intermodal containers are stacked or placed very closely together in the hold or port of a ship to a tolerance of only a few inches, and the outwardly deformed walls may interfere with or interfere with the placement of the containers. Without this factor, 40 foot container side walls are more easily deformed than 20 foot container side walls because these side walls are longer and have no additional support. The amount of force exerted on the side wall of a 40 foot container by a flexible tank filled with liquid should be limited.

However, if the flexible tanks of a 20 foot container are simply "lengthened" or made larger 40 foot containers, the greatest disadvantage of using flexible tanks in large shipping containers is the increased likelihood of leakage or rupture. Sudden movement can result in rupture of the flexible tank (i.e., the flexible tank has no manufacturing defects or "weak spots"). Sudden starts, stops or bumps can cause large waves, creating a large pressure at the end of the flexible tank. The risk of rupture or leakage of the flexible tank is largely dependent on the volume of liquid within it and the length between the ends of the flexible tank. The fluid dynamics vary depending on the shape, proportion and volume of the flexible tank. In particular, flexible tanks of 40 'containers will typically have a lower profile (height) than flexible tanks of 20' containers. Fig. 3(a) -3(c) show a seamed end seam in a prior art flexible tank. These end seams are subject to hydrodynamic effects (as indicated by the arrows in fig. 3 (c)) which affect the end seam at the intersection where it is sewn together, forcing its two halves apart and away from each other.

Thus, even with large shipping containers, large known flexible tanks have historically not been feasible due to the risk of rupture. For example, in U.S. patent application publication No.2017/0144833 filed by Environmental Packaging Technologies, inc, three different flexible tanks are used in a 40 foot or 53 foot container, rather than one larger flexible tank. A disadvantage of this system is that each flexible tank must be loaded and unloaded individually and the cost of three flexible tanks is higher than the cost of only one flexible tank. Historically, it has not been possible to use a single large flexible tank in large shipping containers due to possible cracks or leaks.

For intermodal transportation, in certain situations where large containers are to be transported by rail, the risk of leakage where the flexible tank body breaks is even greater. Particularly when loaded, railway cars are large and heavy. Railway cars are typically connected to each other by hitting them against each other so that they are hooked together in a process sometimes referred to as shunting. Even at low speeds, these collisions produce very large and very sudden deceleration forces, such as 2G of deceleration force, which equates to the deceleration force experienced at a sudden full stop. This problem has been solved by the preferred embodiments of the present invention. In particular, while the flexible tank of the preferred embodiment of the present invention is freestanding, disposable, and made for use, in particular, in a 40 foot shipping container, it does not leak or rupture even when repeatedly impacted by a rail car collision.

Drawings

Fig. 1(a) shows a flexible tank for a 40 foot shipping container (when the flexible tank is partially filled with liquid) according to a preferred embodiment of the invention.

Fig. 1(b) shows an alternative preferred embodiment using a capacity belt.

Fig. 2 is a schematic illustration of a railway vehicle undergoing an impact that the preferred embodiment of the present invention experiences without leaking, cracking or damaging a container in which it is placed.

Fig. 3(a) -3(c) show end seams of prior art flexible cans.

FIG. 4 illustrates a preferred embodiment of an enhanced strength end seal.

Fig. 5 shows a schematic view of the assembly of the end seal in fig. 4.

Fig. 6 is an exploded view of the end seal of fig. 4.

Fig. 7(a) to 7(e) show steps of forming a flexible tank according to a preferred embodiment.

Fig. 8 is a perspective view of an end seal in a preferred embodiment of the invention.

Figure 9 shows an alternative preferred embodiment in which end caps are used to further strengthen the end seals of the flexible tank.

FIG. 10 shows an end view of an exemplary baffle for use in connection with a flexible tank in accordance with one of the preferred embodiments.

FIG. 11 illustrates a side view of an exemplary baffle for use in connection with a flexible tank in accordance with one of the preferred embodiments.

Detailed Description

Of course, the actual impact on a large shipping container when it is on a rail vehicle cannot be determined in advance during a particular intermodal segment. However, they can be predicted and simulated. It is believed that the preferred embodiment of the present invention achieves for the first time that these impacts can be satisfactorily withstood without causing leaks, cracks, buckling of the bulkhead fixing rods, damage or deformation of the container walls. A typical simulated impact test is shown in figure 2.

A railway vehicle fitted with a shipping container and flexible tank is released with approximately 0.8% rail degradation to a train of empty anvil cars with standard traction equipment and a total weight of 250,000 pounds (113.40 metric tons), with air brakes on all impacting vehicles and hand brakes on the first and last cars. The predetermined location is selected such that the speed of the railway vehicle fitted with the flexible tank is about 4-6 miles per hour (mph) at the point of impact.

Fig. 1(a) shows a preferred embodiment of a flexible tank according to the invention placed on the floor of a transport container (horizontal cross-section). The flexible tank is shorter than the internal length of the shipping container and its ends are lower than the end walls of the container. It consists of three layers of low density polyethylene (preferably 125x2 microns thick) and a woven polypropylene jacket or outer layer (preferably 550x2 microns thick). The cover layer provides additional strength along the length of the flexible tank that will absorb and control internal hydrodynamic forces during transport. A cover layer for a flexible storage tank is preferably constructed of 610 grams per square meter of vinyl fabric layer on a base reinforcing scrim of 14 x 14 or 20 x 20 per centimeter of polyester thread. This relatively high thread count of the scrim provides additional strength for the transport of liquids having a higher specific gravity than water. The diameter of the covering outer layer depends on the desired capacity of the flexible tank. The top of the flexible tank may have only one fill/drain port or may have a top fill port and a drain valve at one end of the flexible tank.

The preferred dimensions of the flexible tank for a 40 foot container according to the preferred embodiment of the invention are 40.5 feet long by 9.6 feet wide and about 27 inches high when loaded, thus having a capacity of 5,812 U.S. gallons (22,00 liters). After filling, the top is slightly domed, higher in the middle than at its ends and sides. See fig. 1 (a). Another important aspect of the preferred embodiment is the situation where the flexible tank is not full. This is counter-intuitive in view of the concern of one about the waves that cause the flexible can end to rupture. The previous idea was that if the flexible tank was filled completely so that there was no empty air space, waves could not form that would propagate from end to end, which could risk breaking. The inventors believe that hydrodynamics are still generated by the sudden impact of pressure on the ends. In addition to the improved end seal, the preferred embodiment also employs a different approach in terms of capacity. The flexible tank is intentionally unfilled. For example, for a flexible tank having a capacity of 5,812 U.S. gallons (22,000 liters), it is only partially filled, preferably 5,425 U.S. gallons (20,560 liters).

Capacity bands may optionally be used at various points along the length of the flexible tank to adjust the capacity of the flexible tank, for example, to allow for the transport of liquids of different specific gravities while remaining within weight limits. When fully filled, the length of the band is slightly less than the circumference of the flexible tank. Thus, the straps "squeeze" the flexible tank, giving the flexible tank a four-humped shape and affecting the capacity of the flexible tank, as shown in fig. 1 (b). The number and length of the bands affect the capacity of the flexible tank to a different extent. The number of belts may be increased and/or the belts may be made shorter to reduce capacity. For the dimensions provided above, the preferred attachment length of the strap includes a circumference of 122 inches. Preferably, the bands are arranged in a symmetrical manner along the length of the flexible tank, so as to avoid any disproportionate influence on the hydrodynamics. There may be three bands with the middle band in the center. Alternatively, an even number of straps may be spaced proportionally along the length of the flexible tank.

An important aspect of the capacity of the bands is that they are separate components from the main part of the flexible tank and are selected at the time of installation according to the liquid to be transported. This enables the major part of the flexible tank to be produced in large quantities and its capacity optionally reduced by the selective use of straps. The capacity tape is not sewn or otherwise secured to the main portion of the flexible tank. They surround the outside, somewhat like a belt of a person, and rely on compression to hold them in place. Importantly, the strap does not require buckles or other edged items to be provided in order to set its length or secure it in place. Tests have shown that during transport there is significant wear between the capacity belt and the flexible tank, and care must be taken that the capacity belt itself does not cause leakage or puncture. Preferably, the ends of the capacity belt are sewn together to form a continuous loop. A suitable construction for the capacity belt is a two inch wide fabric made from a blend of polyester and nylon materials.

Another key feature of the preferred embodiment is the improved end seal shown in fig. 4-8. In contrast to the prior art seamed ends shown in fig. 3(a) -3(c), they close both ends of the can and provide additional strength to the heat sealed end seam of the inner can, thereby preventing the seam from rupturing when pressure from the force of a liquid is applied thereto. The result is a flexible tank that is overall stronger at the ends than conventional flexible storage tanks.

Fig. 7(a) -7(e) illustrate a process of forming a flexible tank, according to a preferred embodiment of the present invention.

In a first step, long narrow fabric layers are welded together longitudinally, preferably by Radio Frequency (RF) welding, to form top and bottom outer layers. As shown in fig. 7(a), the ends of the top and bottom layers are welded back to themselves, forming a loop large enough to accommodate the nylon cord.

In a second step, the end flaps are welded to the inside of the bottom layer approximately 30 to 36 inches from each end of the bottom layer. Preferably, the end flaps are of the same fabric as the top and bottom outer layers. The end flap has the same width as the top and outer layers and is about 7 to 8 feet in length. At this point, the end flap extends beyond the end of the base layer, as shown by the dashed line a in fig. 7 (b). When the manufacture of the bag is complete, the end flaps will be positioned as shown by the dotted lines B in fig. 7 (B). It should be understood that although not shown in the cross-sectional view, the longitudinal sides of the top and bottom layers are welded to each other to form an open tube.

In a third step, as shown in fig. 7(c), the looped ends of the top and bottom layers are cut at the same location to form respective equal sized portions of the looped ends. Odd rings are removed from one of the layers and even rings are removed from the other layer so that the layers have alternating interleaved rings in a door hinge fashion. The number of loops depends on the width and preferably each loop is 6 cm long. The rings are positioned in such a way that: in the flat position, the rings of the top and bottom outer layers will be adjacent to and alternate with each other in a staggered manner. See fig. 4-6.

In a fourth step, the top mounted carrier/discharge valve is attached to the liner through an opening in the top outer layer that is centered widthwise and is located lengthwise near the end seam, preferably about 30 to 36 inches from the end seam. Preferably, the valve is secured using a clamp. An inner liner layer, 2-4 layers of which have been formed and welded together at the ends, is inserted into the open end of the bag near the valve and between the top and bottom layers. Any "coupon" of the liner at the closed end of the bag is folded so that it lies flat against the outer layer. Any "coupon" of the liner at the closed end of the bag is folded and then the additional fabric layer is removed from the position of dashed line a as shown in fig. 7(b), covering the end and coupon of the liner as shown in fig. 7(d) and positioned on top of the liner.

In the final step, the nylon string is passed completely through the seam through alternating loops at the open end of the bag. The rope closes the seam and secures the flexible tank to the cover. Alternatively, grommets may be used instead of alternating rings to tie them together. As shown in fig. 7(e), when the bag is filled with liquid, the liner expands pushing against the end flap and the end seal with the band. It is noted that the ring in the end seal is not watertight, nor is it intended to be watertight. The end flaps provide some protection against leakage but primarily provide additional strength to the end seal. The end flap contains an inner liner inside the outer layer of the cover layer to prevent direct contact with the end seal. As shown in fig. 8, the loops do not remain aligned and the cords do not remain straight when filling the flexible tank, but they do provide a very strong end seal.

The closure provides extremely high strength, which is particularly useful for end closures for flexible cans. However, the use of the closure is limited to the preferred embodiments described herein. It can also be used on the sides of rectangular flexible tanks, or anywhere where higher strength is required instead of sewn seams. The end seals herein are based on those disclosed in PCT international application PCT/US2018/058530 filed on 31.10.2018 and U.S. provisional patent application 62/579,612 filed on 31.10.2017, the disclosures of which are incorporated herein by reference.

Fig. 9 shows another preferred embodiment of the end seal. In addition to the inner and outer layers and end flaps C of the preferred embodiment shown in fig. 7(a) -7(e), additional end caps C are secured to the ends of the inner layer. End cap C is formed from a PVC fabric layer in a rectangular shape, and for a flexible tank having the preferred dimensions described above, end cap C is approximately 116 "wide x 60" long. It was folded in half so that it was overall 116 "wide x 30" long. The folded material was then welded to the 30 "long side to make the product in canoe-like shape after filling with water. This additional layer at the critical point adds strength to the end seal system as a whole. The end cap C helps to form the shape of the flexible tank and further enhances its ability to resist the large hydraulic forces caused by sudden starts, stops and bumps of the railway vehicle.

In addition to the above features, in the case of a container having a door recess channel directly inside the door, the partition system can be inserted into the recess channel. The baffle system may be the baffle system shown in the end view of fig. 10 and the side view of fig. 11. A plurality of square bars 5 of 3/16 steel pipes are arranged in the slots of the door columns. Although five rods are shown in fig. 10 and 11, there may be four or six such rods. The bottom telescopic rod 2 is preferably formed of steel tubing and comprises an inner telescopic steel tube 3. The two vertically oriented short strips 4 are preferably flat steel rods, said short strips 4 securing the steel rods 5 and the telescopic steel rods 2 together, for example with hex bolts at the overlap of the steel rods and each short strip. The steel rods 5 and telescoping steel rods 2 are extended horizontally to secure the bulkhead into the recessed channel with a 2 inch clearance from the bulkhead to the door. Corrugated polypropylene corrugated plates 1 are fixed to the rods 5 and telescopic rods 2 of each partition by passing a tie through the corrugated plates 1 and around the respective rods. The plate is preferably thick, for example 10-12 mm. The container walls are also lined with single wall corrugated paper, preferably without any additional side or wall reinforcement.

Claims

1. A flexible tank for transporting liquid or semi-liquid material in bulk in a transport container on a railway vehicle, comprising:

an inner vessel made of a flexible, water-resistant polymeric material, the inner vessel being generally rectangular in shape, wherein at least one end of the inner vessel has a width less than the length of the inner vessel, the inner vessel enclosing transported bulk liquid or semi-liquid material therein;

a generally rectangular first outer layer of flexible polymeric material having a first end with a series of hollow rings and voids between the rings widthwise along the first end, the rings alternating with voids in sequence;

a second outer layer made of a flexible polymer substantially similar in shape and size to the first outer layer, a first end of the second outer layer having a series of hollow rings and voids therebetween, the hollow rings alternating with the voids sequentially in a width direction of the first outer layer, the first end of the second outer layer cooperating with the first end of the first outer layer such that the hollow rings of the second outer layer occur at void locations of the first outer layer and the voids of the second outer layer occur at void locations of the first outer layer;

a plurality of capacity bands disposed about a periphery of the second outer layer, each of the plurality of capacity bands restricting expansion of the flexible tube at a location thereof during movement of the railway vehicle; and

a cord passing through alternating hollow loops of the first and second outer layers and connecting the first and second outer layers to each other, the inner tank being confined within the first and second outer layers connected by the cord.

2. The flexible tank of claim 1, wherein the flexible tank is less than the length of the shipping container and is not supported by the end walls of the shipping container.

3. The flexible tank of claim 1, wherein the flexible tank has a capacity of over 8000 liters.

4. A flexible tank method for transporting bulk liquid or semi-liquid material in a transport container on a railway vehicle, comprising:

folding the ends of rectangular first and second layers of flexible polymeric material to form a continuous loop across the width of the ends of the first and second layers;

connecting the longitudinal sides of the first and second layers to form an open tube;

attaching a first end of a first end flap to the interior of one of the first and second layers near a first end of the open tube and attaching a first end of a second end flap to the interior of one of the first and second layers near a second end of the open tube, the first end flap having a length greater than the distance from its attachment point to the first end of the open tube and the second end flap having a length greater than the distance from its attachment point to the second end of the open tube;

cutting out a portion from each successive loop of said ends of said first and second layers so as to be a series of alternating hollow loops and voids, the hollow loops and voids of the first layer being joined with the hollow loops and voids of the second layer;

inserting a liner into the interior space of the open tube formed by the longitudinal sides connecting the first and second layers, the liner being made of a flexible waterproof polymeric material, thereby enclosing the transported bulk liquid or semi-liquid material therein;

moving the respective second ends of the first and second end flaps to cover the ends of the liner;

closing the first and second ends of the flexible tank by passing a cord between the interleaved hollow loops of the first and second layers to confine the inner liner and the end flaps therein; and

a plurality of capacity bands disposed around an outer periphery of the flexible tank, each of the plurality of capacity bands limiting expansion of the flexible tube at its respective location during movement of the railway vehicle, the flexible tank reliably free of leakage during acceleration and deceleration of the railway vehicle.

5. The flexible tank of claim 4, wherein the flexible tank is less than the length of the shipping container and is not supported by the end walls of the shipping container.

6. The flexible tank of claim 4, wherein the flexible tank has a capacity of over 8000 liters.