System for offloading covered hopper railcar

A system for offloading a covered hopper railcar includes first and second auger-based conveyors. The first conveyor is adapted to fit partially under a covered hopper railcar's offloading gate when the covered hopper railcar is at rest on track rails such that a portion of the first conveyor is located to a side of the track rails. The first conveyor has a first opening in a top thereof adapted to be coupled to the offloading gate, and has a second opening in the portion thereof located to the side of the track rails. The second opening is in a bottom of the first conveyor. The second conveyor is coupled to the second opening of the first conveyor.

The invention relates generally to bulk material handling systems, and more particularly to a system for offloading bulk material from a covered hopper railcar resting on a railroad track's rails.

BACKGROUND OF THE INVENTION

Covered hopper railcars are used to transport a variety of dry and moisture-sensitive bulk materials by rail. The bulk materials can include corn, wheat barley, rice, sugar, fertilizer, soda ash, cementitious materials, sand, and roofing granules.

In general, a covered hopper railcar has rigid sides and ends, a roof with watertight hatches, and a floor with gates that can be opened and closed. The inside of a covered hopper railcar is divided into bays having sloped floors where each bay's sloped floors lead to a gate. In operation, bulk material is loaded into a covered hopper railcar's bays via its rooftop hatches with its floor's gates in their closed configuration. After loading, the hatches are sealed to protect the bulk material from moisture intrusion. When the railcar is transported to its destination and the bulk material is to be offloaded, the gates are opened and the bulk material flows out of the railcar under the force of gravity. The flow of the bulk material out of a gate is generally handled by some type of offloading equipment.

Ideally, the offloading equipment used to handle the bulk material exiting a covered hopper railcar's gates should have a handling capacity that matches or exceeds the throughput capacity of the gates. Unfortunately, existing offloading systems used with covered hopper railcars do not achieve this goal thereby leading to time-consuming and, ultimately, costly offloading operations.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a system that can efficiently offload bulk material from a covered hopper railcar.

In accordance with the present invention, a system for offloading a covered hopper railcar includes first and second auger-based conveyors. The first auger-based conveyor is adapted to fit partially under a covered hopper railcar's offloading gate when the covered hopper railcar is at rest on track rails such that a portion of the first auger-based conveyor is located to a side of the track rails. The first auger-based conveyor has a first opening in a top thereof adapted to be coupled to the offloading gate. The first auger-based conveyor has a second opening in the portion thereof located to the side of the track rails. The second opening is in a bottom of the first auger-based conveyor. The second auger-based conveyor is coupled to the second opening of the first auger-based conveyor.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings, simultaneous reference will be made toFIGS.1and2where a system for offloading a covered hopper railcar100in accordance with an embodiment of the present invention is shown and is referenced generally by numeral10. System10is shown in its pre-offloading configuration inFIG.1and in its offloading configuration inFIG.2.

Railcar100has the attributes of a conventional covered hopper railcar as would be well understood in the art. Briefly, railcar100has rigid sides, rooftop hatches for the purpose of loading railcar100with a dry bulk material, and multiple bottom gates for the purpose of offloading of the dry bulk material via gravity. Railcar100can be used to transport a variety of food and non-food dry bulk materials. By way of an illustrative example, system10will be described for its use in offloading dry cementitious materials from railcar100. For clarity of illustration, the bulk material will not be shown in any of the figures.

For purpose of describing system10, reference will be made to a single bottom gate102of railcar100. However and as will be explained further below, some embodiments of the present invention can be adapted to simultaneously offload bulk material from multiple gates of a railcar in order to maximize offloading efficiency.

When railcar100is to be offloaded, railcar100is at rest on the rails202of a railroad track200disposed on a ground region300. For clarity of illustration, the railcar's trucks and wheels are omitted from the figures. With railcar resting on rails202, the bottom of gate102is spaced apart from the top of rails202by a distance “h” that is at its minimum when railcar100is fully loaded. Railcar100moves upward such that distance h increases as bulk material is offloaded from railcar100. Distance h can increase by as much as 2 to 3 inches during an offloading operation.

System10includes at least one auger-based mobile conveyor20and at least one auger-based fixed conveyor40. Each mobile conveyor20is movable between its pre-offloading position (FIG.1) and its offloading position (FIG.2) as indicated by two-headed arrow12. Each mobile conveyor20is a self-contained unit housing at least one pair of augers (not shown inFIGS.1and2) driven to rotation in order to transport bulk material exiting gate102to a position adjacent to railroad track200during an offloading operation as shown inFIG.2. Since each mobile conveyor20is identically configured, it is sufficient to describe one mobile conveyor20.

Mobile conveyor20includes a housing21whose height “H” is less than the distance h between gate102and the top of rails202when railcar100is fully loaded. The top of housing21has an opening at one end thereof indicated by dashed line22. The bottom of the other end of housing21has an opening therein indicated by dashed line23. When mobile conveyor20is positioned for offloading (FIG.2), opening22is aligned with and coupled to gate102, while opening23is located adjacent to track200. Briefly, when mobile conveyor20is in its offloading position (FIG.2), the augers in conveyor20are rotated. Gate102is opened and the bulk material in railcar100flows out of gate102and into housing21via opening22. The bulk material entering housing21is transported to opening23where the bulk material exits housing21under the force of gravity.

Each auger-based fixed conveyor40is coupled to ground region300adjacent to track200by a support structure indicated generally by numeral42. In general, fixed conveyor40is an enclosed structure housing an auger that receives bulk material at one end44as the bulk material exits the mobile conveyor's opening23. Fixed conveyor40transports the received bulk material along the length of fixed conveyor40to its second end46. Typically, the bulk material exiting second end46falls into a load spout48configured to support transfer of the bulk material to a ground-based vehicle, conveyor, etc., the choice of which is not a limitation of the present invention. In general, fixed conveyor40is configured to have a throughput capacity that is greater than that of mobile conveyor20in order to prevent clogs from developing between opening23of mobile conveyor20and end44of fixed conveyor40.

In order to take advantage of the force of gravity acting on the bulk material exiting the mobile conveyor's opening23, system10can include a rigid sleeve50countersunk into ground region300adjacent to track200such that end44of fixed conveyor40will be positioned beneath opening23during an offloading operation (FIG.2). A movable and/or flexible sleeve52can be used to couple opening23to end44to accommodate movements of mobile conveyor20during an offloading operation as will be explained further below.

As mentioned above, the distance h between the bottom of gate102and the top of rails202increases as railcar100offloads its bulk material load. In order to keep opening22coupled to gate102as railcar100rises, the present invention can incorporate a lift that raises housing21in correspondence with the rise of railcar100. For example and as shown inFIG.3, one or more pressure sensors (“PS”)24can be disposed between opening21and gate102. When railcar100is fully loaded and opening21is coupled to gate102, pressure sensor(s)24register a baseline pressure that is supplied to a lift25via a wired or wireless connection (not shown for clarity of illustration). The type of connection between pressure sensor(s)24and lift25is not a limitation of the present invention. As railcar100is offloaded and rises, pressure sensor(s)24will detect a decrease in pressure that is supplied to lift25. In turn, lift25applies a lifting force F L to mobile conveyor20in order to maintain pressure at pressure sensor(s)24at the initial/baseline pressure. The inclusion of flexible sleeve52accommodates the above-described upward of movement of mobile conveyor20.

As mentioned above, mobile conveyor20includes at least one pair of augers. Referring additionally now toFIG.4, a single pair30of augers31and32is shown in isolation. Augers31and32are spaced apart from one another and are parallel to one another such that a constant gap “D” is maintained there between. Augers31and32are rotated about their respective longitudinal axes31A and32A in opposite directions33(e.g., clockwise) and34(e.g., counterclockwise) and at the same speed in order to drive material in gap D along the length of the augers. The size of gap D and the speed of rotation are selected based on the type of bulk material and required throughput.

In some embodiments of the present invention, multiple pairs of augers are provided in mobile conveyor20. One such embodiment is illustrated inFIGS.5and6where two pairs30of augers31/32are provided in housing21. In the top plan view shown inFIG.5, the top of housing21is omitted in order to better illustrate the features of the embodiment. Each pair30of augers31/32is disposed in a bay26defined in and extending along the length of housing21. Each pair30spans the opening in the top of housing21(i.e., opening22as described above but not shown inFIG.5) and bottom opening23. With additional reference to the cross-sectional view presented inFIG.6, each bay26is trough-shaped along its length with its base or bottom corners27being concavely-curved along the length of bay26between openings22and23. The radius of curvature of concavely-curved bottom corners27is selected to facilitate continued movement of the bulk material along the length of housing21as augers31and32are rotated.

Each auger31and32in both pairs30is simultaneously driven to an identical speed of rotation by a motor/driver35coupled to housing21. Typically, motor/driver35is mounted to housing21at the end thereof nearest opening23located in the bottom of housing21. In some embodiments of the present invention and as illustrated inFIG.7, motor/driver35includes an endless belt36that is coupled to all augers31and32in a serpentine fashion to bring about the above-described counter rotations33and34when belt36is driven in a direction37.

As described above, mobile conveyor20must be movable between a pre-offloading state where it is clear of track200to an offloading state where it is partially disposed under railcar100. To assure proper alignment with a railcar's gate, the system of the present invention can mount each mobile conveyor20on its own rail (or rails) fixed to the ground region adjacent to where the railcar is to be offloaded. For example and as illustrated inFIG.8, mobile conveyor20is mounted for back-and-forth movement12along a rail (or rails)60that can be affixed to ground region300adjacent to track200. Rail(s)60can be perpendicular to rails202of track200. Movement of mobile conveyor20on rail(s)60can be a manual or mechanized operation without departing from the scope of the present invention.

As mentioned above, covered hopper railcars typically have multiple gates at the bottom thereof. To decrease or minimize offloading times, another embodiment of the present invention includes multiple mobile conveyors and multiple fixed conveyors. An example of this embodiment is illustrated inFIG.9where rigid sleeve50extends along a portion of a railroad track where a railcar (track and railcar not shown inFIG.9for clarity of illustration) is to be offloaded. The length of sleeve50should be long enough to accommodate the number of railcar gates that are to be simultaneously offloaded. Each mobile conveyor20is independently movable, incorporates the features described previously herein, and can be rail-mounted at the ground region as described above. Fixed conveyors40are coupled to one another and to ground region300by support42. Each fixed conveyor40cooperates with one mobile conveyor20via a corresponding flexible sleeve52as previously described herein. Fixed conveyors40deposit their transported bulk material into a common repository70whose outlet72is configured as needed (e.g., an offloading spout) to support further transport of the bulk material.

The advantages of the present invention are numerous. The combination of mobile and fixed conveyors allows bulk material to be efficiently offloaded from a covered hopper railcar. The unique auger-based mobile conveyor moves dry bulk material (e.g., cementitious material) efficiently along its length. An adaptive lift system can be included to keep the mobile conveyor optimally positioned against a railcar's gate throughout an entire offloading operation. In some embodiments, the system is configured to simultaneously offload multiple gates of a covered hopper railcar to greatly reduce the time needed for an offloading operation.