Patent Application
20170225874
The embodiments herein relate generally to systems and methods for safely transporting granular material, and, more specifically, to improved systems and methods for safely transporting granular agricultural and industrial materials such as cement, barite, and sand for use in hydrocarbon fracking operations.
Working with certain types of granular material can pose significant health risks. According to the U.S. Occupational Safety & Health Administration (“OSHA”), inhalation of small crystalline silica particles puts workers at risk for silicosis, lung cancer, chronic obstructive pulmonary disease, as well as liver, heart, and kidney disease. With the increase of hydraulic fracturing (“fracking”) over the past 5-10 years, the instances of sicknesses and deaths due to silica inhalation have rapidly increased. Many fracking sites fail to meet current OSHA standards. Moreover, OSHA has proposed a new rule lowering the permissible exposure limit of respirable crystalline silica per cubic meter of air. This lower limit will impact almost any industry that involves transporting or otherwise using silica.
Fracking is a process for stimulating an oil well by fracturing underground rock using a pressurized liquid. The pressurized liquid consists primarily of water mixed with a proppant. A typical proppant is sand, such as “frac sand,” although other granular materials can be used as well. The proppant functions to maintain an induced hydraulic fracture open such that the desired oil or gas can be extracted. A single fracking well can require several thousand tons of frac sand.
Frac sand is mined and processed in a plant to improve its performance characteristics. The sand then gets transported from the plant to the fracking site. This transportation process can involve trains, ships, trucks, conveyors, and other transportation methods. Pneumatic pipe systems and conveyors are routinely used to transport sand from one container to another—for example, from a rail car to a truck or from a truck to a storage facility. Pneumatic and conveyor transfers allow silica particles to permeate the air in the surrounding area, causing a potential health hazard to any workers nearby.
In addition to the health hazards, the typical processes for transporting frac sand have additional drawbacks. For example, a container (e.g., a rail car or a truck) designed to hold frac sand may not be useful for carrying other items. That is, once the load of frac sand has been deposited, the rail car or container cannot be used for another purpose; instead, it must be returned to a location where it can be refilled with frac sand. The lack of reusability increases transportation costs and, as a result, the overall cost of fracking.
Therefore, a need exists for systems and methods for safely and efficiently transporting granular material. More specifically, a need exists for systems and methods for transporting granular material in a manner that limits respirable silica emissions, eliminates harmful pneumatic transfers, and provides lower transport costs.
Embodiments described herein include systems and methods for safely and efficiently transporting granular material. In one embodiment, a method includes providing an expandable container in an unexpanded state, expanding the expandable container from the unexpanded state to an expanded state, and depositing granular material within the expandable container via an input valve. In this embodiment, the expandable container includes at least a top plate, a bottom plate, an outer material coupled to the top and bottom plates, an input valve associated with the top plate, and a discharge valve associated with the bottom plate. The expandable container can also include a containment bladder for holding of the granular material within the container and protecting it from the elements, and a discharge bladder for assisting in discharging the granular material from the container.
In another embodiment, the method also includes transporting the expandable container. The method can further include discharging granular material from the expanded container via the discharge valve. The discharge bladder may be inflated in a manner that urges or biases the granular material within the containment bladder toward the discharge valve. Discharging the granular material may cause the expandable container to return to its unexpanded state. Once in its unexpanded state, the expandable container may be stacked on top of a similar expandable container, also in an unexpanded state, for transporting. This can, for example, require half or fewer train cars to return the expandable containers than is needed for transporting the full containers.
In one embodiment, the expandable container includes a restraint device removably coupled to the top and bottom plates and/or support members associated with the top and bottom plates. Expanding the expandable container may include the step of removing the restraint device.
In yet another embodiment, an expandable container is provided for safely transporting granular material. The expandable container can include a top plate, a bottom plate, an outer material coupled to the top and bottom plates, an input valve associated with the top plate, and a discharge valve associated with the bottom plate. Furthermore, the expandable container can be expanded by applying opposing forces to the top and bottom plates, respectively.
The expandable container may include a containment bladder coupled to the top and bottom plates. The outer material may include at least one Kevlar or Kevlar-reinforced band, and/or may be coupled to the top and bottom plates via retaining rings. The input valve and/or discharge valve may include a spring-loaded plate. A discharge bladder may be included, and can be positioned outside the containment bladder and inside the outer material. The discharge bladder can be configured to be inflated via an inflation port. Once inflated, the discharge bladder can provide a shape that biases the granular material within the containment bladder toward the discharge valve.
The expandable container can also include a restraint device that can be removably coupled to the top and bottom plates, thereby limiting the vertical expansion of the container. The top and/or bottom plates of the expandable container can also include reinforcement members. These reinforcement members can be coupled to the input and/or discharge valves, respectively.
In another embodiment, a container for granular material is provided. The container can have a top plate and a bottom plate. The top plate and bottom plate can be coupled to one another via a fabric sleeve. Multiple fabric sleeves can be used to couple the top and bottom plates to one another. As explained further below, the word “fabric” can encompass any type of non-rigid or partially rigid material, such as KEVLAR or a steel- or carbon-fiber-reinforced fabric material. The bottom plate can include a discharge valve for discharging the granular material in the container.
The container can also include a discharge bladder that, when inflated, biases granular material within the container toward the discharge valve. The container can also include at least one barrier positioned proximate the discharge valve such that the barrier prevents at least a portion of the discharge bladder from entering the discharge valve. The barrier can allow sand or other granular material to pass through the barrier and exit through the discharge valve.
The barrier can be frustoconically shaped in one example. This includes a plurality of barriers that, when view collectively, form the basic shape of a frustrum or a cone. For example, the barrier can include a plurality of members extending away from the discharge valve. In one example, at least one of the members is mounted such that it extends away from the discharge valve, wherein a proximate end of the member is positioned closer to a longitudinal axis of the container than a distal end of the member. The barrier can further include at least one ring mounted to at least two of the plurality of members.
In one embodiment, a sealed container is provided for granular material. The sealed container can include a rigid upper portion having an inlet and a rigid bottom portion having an outlet. The container can also include a first, second, and third fabric sleeve. The first fabric sleeve can have a first open end and a second open end, with the first open end coupled to the inlet of the upper portion and the second open end coupled to an upper mounting location of the upper portion. The second fabric sleeve can have a third open end and a fourth open end, with the third open end coupled to the outlet of the bottom portion and the fourth open end coupled to a lower mounting location of the bottom portion. The third fabric sleeve can have a fifth open and a sixth open end, with the fifth open end coupled to the second open end of the fabric sleeve via the upper mounting location of the upper portion, and the sixth open end coupled to the fourth open end of the second fabric sleeve via the lower mounting location of the bottom portion.
The container can also include a fourth fabric sleeve having a seventh open end and an eighth open end. The seventh open end can be coupled to the fifth open end of the third fabric sleeve and the second open end of the first fabric sleeve via the upper mounting location of the upper portion. The eighth open end can be coupled to the sixth open end of the third fabric sleeve and the fourth open end of the second fabric sleeve via the lower mounting location of the bottom portion.
In one example, the upper and lower mounting locations can include a pair of clamp rings spaced to receive a compression strap therebetween. The compression strap can be made from metal but tightened around the container to retain one or more layers of fabric against the container. For example, coupling to the upper or lower mounting location can include compressing a portion of at least one of the first, second, or third fabric sleeves between the pairs of clamp rings via a compression strap.
In another embodiment, a container for granular material is provided that includes a cylindrical top plate and a cylindrical bottom plate. The bottom plate can include a discharge valve centered in the bottom plate. The bottom plate can also include a pair of fork lift boots coupled to the bottom plate on either side for the discharge valve.
In one example, each of the pairs of fork lift boots is welded to the bottom plate. The fork lifts boots can be open on either end, such that they are accessible by a forklift from multiple directions. The top and bottom plates can each include a plurality of slots, where each slot is configured to couple to a lift tube for lifting or anchoring the container. In one example, the top plate includes a hollow metal tube coupled along a perimeter of the plate. The bottom plate can include a similar hollow metal tube along its perimeter.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to restrict the scope of the invention as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate various embodiments and aspects of the present invention. In the drawings:
Reference will now be made in detail to the present exemplary embodiments, including examples illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
The containers described herein may be used to store and transport granular material, such as frac sand. In one example embodiment, the container may have a containment volume of about 500 cubic feet. In that example, the container may be about 10 feet tall in its expanded state and have a diameter of about 8 feet. The height and diameter, and therefore the containment volume, of the container may be varied according to the particular transportation needs of a project. For example, the container may have an expanded height of between 6-14 feet, and may have a diameter of between 4-12 feet. Other sized may be used as well, and these examples are not intended to limit this disclosure in any way.
The outer material 130 can be constructed from a robust yet flexible material such as, for example, Kevlar or other material having similarly high elastic modulus and/or tensile strength measurements. For example, the outer material 130 can be made from a fabric having an elastic modulus of between about 100 and 200 GPa. In some examples, the outer material 130 can be made from a material having a tensile strength of between about 2000 and 4000 MPa. In other examples, material having characteristics outside of these ranges can be used. However, a material with these characteristics can prevent bulging and thereby maintain the uniform cross-sectional diameter of the container as the outer material. The outer material 130 functions to contain the contents of the expandable container 100, including any internal bladders or containment vessels. The outer fabric material 130 can be stronger than steel, on a per-weight basis. However, it also provides flexibility such that the expandable container 100 can be expanded or contracted in an efficient and reliable manner. At the same time, however, the outer material 130 is strong enough to resist tearing or rupturing during use, which may involve heavy machinery and large forces or loads.
For increased strength and overall robustness of the container, support members 160 may be coupled to the top plate 110 and/or bottom plate 120. The support members 160 provide increased rigidity of the top and bottom plates 110, 120, and enable multiple expandable containers 100 to be stacked on top of one another. The support members 160 also provide a mechanism to manipulate the expandable container 100 itself. For example, the loading process may require the top plate 110 to be lifted and/or vibrated to efficiently fill the containment volume with granular material. In this scenario the top plate 110 can be gripped via support members 160 and manipulated as needed. The container 100 can be filled with sand while lifted, allowing the weight of the sand to expand the container 100 downward. Then the full container 100 can 100 can be placed on a train car or other transport.
Additionally, support members 160 can be used to temporarily fix the height of the expandable container 100. As discussed further with respect to
With respect to
A valve plate 210 can be used to control the flow of material into or out of a valve. The valve plate 210 can be provided as a circular disk with a hole that accommodates valve shaft 220, such that the valve plate 210 can slidably move along the valve shaft 220. A biasing mechanism, such as a spring 240, can be used along at least a portion of the valve shaft 220. Spring 240 biases the valve plate 210 in a manner that will cause the valve plate 210 to sit flush with the top plate 110 in its resting position (i.e., when no external forces are being applied to the valve plate 210). A valve pin 230 can be provided along the valve shaft 220 to abut one end of the spring 240, while the other end of the spring 240 abuts the valve plate 210.
To operate the input valve 140, the valve plate 210 is depressed such that it moves along the valve shaft 220 toward the valve pin 230, compressing the spring 240. In practice, the valve plate 210 can be depressed by a loading apparatus. For example, the nozzle of a hopper, tube, or pipe carrying granular material can be shaped to contact and depress the valve plate 210. In some embodiments one mechanism is used to depress the valve plate 210 while a separate component provides the granular material. Any device that depresses the valve plate 210 toward the valve pin 230 can be used to open the input valve 140.
As mentioned above, a discharge valve may incorporate the same, or similar, components described in
Discharge bladder 340 can be inflated during the discharge process when the granular material 350 begins to run low. One purpose of the discharge bladder 340 is to prevent granular material 350 from remaining trapped inside the containment bladder 330 due to the flat-bottomed shape of the expandable container 100. Discharge bladder 340 fills in the areas that may trap the granular material 350, thereby urging the remaining granular material 350 to exit the discharge valve 320.
Discharge bladder 340 may inflate automatically, for example by using input from a sensor that determines the amount of granular material 350 remaining in the expandable container 100. In this embodiment discharge bladder 340 may be connected to a built-in pump provided within, or attached to, the expandable container 100. In other embodiments the discharge bladder 340 can be inflated manually by attaching an air hose to the discharge bladder valve 170.
The unexpanded state of
To prepare the expandable container 100 of
If a restraint device is installed such that the container is prevented from expanding, the restraint device is removed at step 520.
At step 530, the expandable container is expanded. This may involve, for example, lifting the expandable container using the top plate, or support members attached to the top plate, and allowing the container to expand via the weight of the bottom plate. This step may also involve some amount of vibration or movement to encourage the container to expand sufficiently.
At step 540, granular material is deposited into the expandable container via an input valve. This step may occur simultaneously with step 530, or may occur after step 530. For example, when the expandable container is lifted from the top plate, pouring sand into the lifted container can provide enough weight to cause the bottom of the container to expand downward. Step 540 includes accessing the input valve by depressing the valve plate, as described with respect to
Step 540 may also include vibrating or otherwise applying force to the expandable container as the granular material is deposited. The application of force spreads the granular material within the expandable container and allows for an uninterrupted flow of material into the container.
At step 550, the filled expandable container is transported to its destination. Because a filled container can be quite heavy, machinery may be used to lift the filled container and place it on a truck, ship, train car, or other transportation device. In some embodiments, the same machinery is used to expand the container at step 530 and load the container at step 550. In other embodiments separate machines are used at each step.
At step 560, the granular material is discharged from the expandable container at its desired location. Depending on the type of transport vehicle used, the filled containers may need to be removed from the transport vehicle before the granular material is discharged. To discharge the material, the container is positioned in the desired location and the valve plate of the discharge valve is depressed, as shown in
Step 570 includes inflating the discharge bladder (or bladders, if the container is equipped with more than one) such that any remaining granular material is expelled through the discharge valve. As described with respect to
At step 580, the now-empty expandable container is provided in an unexpanded state due to its lack of contents. At this step the restraint device may be installed, or reinstalled, such that it connects to at least one support member along the top plate and one support member along the bottom plate. Once secured, the restraint device maintains the unexpanded geometry of the container. This allows for multiple unexpanded containers to be stacked on top of one another—for example, on a truck or other shipping vehicle. Once the unexpanded containers are returned to the storage location for the granular material, they may be filled again starting with Step 510.
The top 600 can include an opening 620 in the center of the top 600. The opening 620 can include any mechanism for receiving sand or other granular material. For example, the opening 620 can be a valve, an inlet, a funnel, or simply an opening the plate through which granular material can be poured.
The top 600 can include a reinforcement ring 630 that provides strength and rigidity to the top 600, as well as providing mounting points for various features and mechanisms of the overall container. As shown in
The reinforcement ring 630 can be coupled to the metal plate 610 via welding, adhesives, epoxy, or can be cast or forged as one piece with the metal plate 610. In one example, the walls of the reinforcement ring 630 are made from 3/16-inch steel, and the reinforcement ring 630 itself is approximately 6 by 2 inches in cross section. In one example, the material used for the reinforcement ring 630 is rated at approximately 50 KSI. Of course, the reinforcement ring 630 can be made from other materials, in different shapes or sizes, or with different wall thicknesses.
The reinforcement ring 630 can also include one or more slots 640 configured to receive lift tubes (not shown) or other attachments. The lift tubes are discussed further with respect to
The reinforcement ring 630 can also include at least one clamp ring 650 coupled to the reinforcement ring 630. In some examples, the clamp ring 650 is attached to a portion of the top 600 other than the reinforcement ring 630, such as an outer wall. In the example of
The base 700 can include a reinforcement ring 730 that provides strength and rigidity to the base 700, as well as providing mounting points for various features and mechanisms of the overall container. As shown in
The reinforcement ring 730 can be coupled to the metal base plate 720 via welding, adhesives, epoxy, or can be cast or forged as one piece with the metal base plate 720. In one example, the walls of the reinforcement ring 730 are made from 3/16-inch steel, and the reinforcement ring 730 itself is approximately 6 by 2 inches in cross section. In one example, the material used for the reinforcement ring 730 is rated at approximately 50 KSI. Of course, the reinforcement ring 730 can be made from other materials, in different shapes or sizes, or with different wall thicknesses.
The reinforcement ring 730 can also include one or more slots 740 configured to receive lift tubes (not shown) or other attachments. The lift tubes are discussed further with respect to
The side plate 710 can include at least one clamp ring 750 coupled to the side plate 710. In some examples, the clamp ring 750 is attached to a portion of the reinforcement ring 730 rather than the side plate 710. In the example of
A bladder can be positioned within the container, such as the bladder 340 shown in
In one example, the barrier 770 can include a plurality of members mounted proximate the valve 790. For example,
In some examples, the members 770 are connected via barrier rings 780. The barrier rings 780 can be metal rings that are mounted to multiple members 770, such as via welding, adhesives, epoxy, or mechanical fasteners. The rings 780 and members 770 can collectively form a frustoconical basket or mesh barrier. that limits expansion of the bladder while allowing granular material to exit the container through the valve 790.
Although the barrier 798 is described as a metal pipe, other types of shapes and materials can be used as well. For example, the barrier 798 can be a PVC pipe. In another example, the barrier 798 is a box with four sides. The barrier 798 can be mounted to the base plate 720 via welding, epoxy, fasteners, or any other suitable methods.
Regardless of its shape, the barrier 798 can include a perforated lid 799 coupled to the barrier 798. The lid 799 can be made from a similar material as the barrier 798 and can include similar perforations. The lid 799 can be coupled using any suitable methods. In some examples, the lid 799 can be removably coupled to the barrier 798 such that it provides easy access to the valve 790 for maintenance or other needs. For example, the lid 799 can be a cap that screws down onto the barrier 798. In another example, the lid 799 includes mounting locations where the lid 799 and barrier 798 interface with one another and can be coupled via, for example, mechanical fasteners.
The barrier 798 of
The valve 790 can include a valve stem 830 in the center of the valve plate, providing a stable base upon which the valve 790 can open and close. The valve stem 830 can be stabilized by the stabilizer beam 820. In the example of
The lift tubes 810 can be made in any shape and from any material, but in the example of
The lift tubes 810 can be used to lift the container, such as by attaching cables to the lift tubes 810 and pulling the cables to lift the container. The container can be lifted via the lift tubes 810 associated with the base 700 of the container, the lift tubes 810 associated with the top 600 of the container, or some combination thereof. The container can also be lifted using all of the lift tubes 810 or some subset of lift tubes 810, depending on the number of lift tubes 810 and their orientation. In some examples, both the base 700 and top 600 of the container each include three or four lift tubes 810. In other examples, more lift tubes 810 can be used. The lift tubes 810 can also be used to secure the container in a vehicle or other transportation by attaching cables, straps, locks, or any other mechanism to the lift tubes 810. Incorporated into each lift tube 810 can be a cam lock receiver. Screw cams can be utilized in a lifting apparatus and/or the bed or a truck or rail car. The screw cams can interface and lock into the cam lock receivers to perform lifting operations or to secure the container.
The steel compression strap can also include a connection 980 that extends outwardly from the straps 970 and container wall 910, allowing for bolts or other fasteners to be utilized. For example, the steel compression strap can include two connections 980 that require a large amount of force to press together. In that example, an operator can install the steel compression strap, align the two connections 980, and insert a bolt of sufficient length through both. The operator can then install a nut on the bolt and tighten the nut, slowly forcing the two connections 980 toward each other. In some examples, the steel compression strap can include multiple sections that each include connections 980 and both ends. In those examples, the steel compression strap can require two, three, four, or more fasteners to fasten the connections 980 to one another accordingly.
The first sleeve 1010 can have an upper opening 1011 and a lower opening 1012. In the example of
Continuing with
The top 600 and base 700 can be coupled to one another via the third sleeve 1030 and, optionally, a fourth sleeve 1040 for additional strength and reinforcement. As shown in
Similarly, the lower opening 1032 of the third sleeve 1030 can be secured to the base 700 at the same location as the upper opening 1021 of the second sleeve 1020. For example, the lower opening 1032 of the third sleeve 1030 can be positioned on top of, and overlapping with, the upper opening 1021 of the second sleeve 1020, positioned between a pair of clamp rings 750 associated with the base 700. Both sleeves can be secured at that location using the same clamping mechanism, such as any of the mechanisms described with respect to
The fourth sleeve 1040 can be layers on top of the third sleeve 1030 in a similar manner, providing extra support and reinforcement for the container. The fourth sleeve 1040 can include an upper opening 1041 and a lower opening 1042. The upper opening 1041 can be can be coupled to the same mounting location as the lower opening 1012 of the first sleeve 1010 and the upper opening 1031 of the third sleeve 1030. For example, the upper opening 1041 of the fourth sleeve 1040 can be positioned on top of, and overlapping with, the lower opening 1012 of the first sleeve 1010 and the upper opening 1031 of the third sleeve 1030, positioned between a pair of clamp rings 650 associated with the top 600. All three sleeves can be secured at that location using the same clamping mechanism, such as the mechanisms described with respect to
Similarly, the lower opening 1042 of the fourth sleeve 1040 can be secured to the base 700 at the same location as the upper opening 1021 of the second sleeve 1020 and the lower opening 1032 of the third sleeve 1030. For example, the lower opening 1042 of the fourth sleeve 1040 can be positioned on top of, and overlapping with, the upper opening 1021 of the second sleeve 1020 and the lower opening 1032 of the third sleeve 1030, positioned between a pair of clamp rings 750 associated with the base 700. All three sleeves can be secured at that location using the same clamping mechanism, such as any of the mechanisms described with respect to
By using multiple sleeves as described above, the container can remain lightweight and cost effective while providing a sealed and secure environment for granular material being shipped. When empty, the containers can collapse to a smaller size due to the flexibility of the fabric sleeves. The sleeves do not compromise the overall strength of the container, as it could still be lifted from the top or bottom as desired.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15002254 | Jan 2016 | US |
| Child | 15494025 | US |
