The present invention relates to drill rigs, and more specifically to an air compressor and air flushing for use with a blasthole drill rig.
Blasthole drill rigs are commonly used in the mining industry to drill through hard rock. Blasthole drill rigs can be found, for example, in coal, copper, and diamond mines throughout the world. A blasthole drill rig typically includes a base, a drill tower extending vertically from the base, and a drill pipe or pipes that are coupled to and supported by the drill tower, and extend into a borehole. The blasthole drill rig also includes an air compressor (e.g., an oil flooded rotary screw air compressor) driven by a diesel engine, that directs compressed air (e.g., at 100 psi) into the borehole to flush bit cuttings and other loose material from the bottom of the borehole to the surface. Current blasthole drill rigs use a substantial supply of compressed air to clear the loose material out of the borehole as a bit is progressed downward. While some drill rigs use water or mud as flushing fluids instead of air, air has proven more advantageous for blasthole drills because it does not need to be transported and stored. However, current blasthole drill rigs utilize the majority of their fuel consumption to produce compressed air, which adversely affects operating costs. Therefore, there is a desire to decrease the fuel required for generating compressed air.
In accordance with one construction, a blasthole drill rig includes a base, a drill tower extending from the base, a drill pipe coupled to the drill tower, a drill bit coupled to a lower end of the drill pipe, an air compressor that directs compressed air through the drill pipe, and a heating element that heats the compressed air.
In accordance with another construction, a method of operating a blasthole drill rig includes directing compressed air through a drill pipe with an air compressor so as to flush bit cuttings from a bottom of a borehole, and heating the compressed air with a heating element.
In accordance with another construction, a drill pipe for a blasthole drill rig includes a body having an upper end and a lower end. The body defines an internal cavity for movement of air between the upper end and the lower end. The drill pipe also includes a plurality of vent apertures spaced between the upper end and the lower end along the body, wherein each of the plurality of vent apertures extends through the body and is in communication with the internal cavity.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limited.
With reference to
The drill rig 10 includes leveling jacks 42 to support the drill rig 10 on the surface 34, a brace 46 that supports the drill tower 14 on the machinery house 18, a drill head motor 50 that drives a rotary drill head 54, and a coupling 58 that couples together the rotary drill head 54 with an upper end of one of the drill pipes 38. The drill rotary drill head 54 is selectively engageable with the upper end of the drill pipe 38 (e.g., via the coupling 58 being screwed onto the upper end of the drill pipe 38), and is movable vertically up and down the mast 14 (e.g., with rollers).
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The drill rig 10 further includes a heating element 138 that directly heats the compressed air. In the illustrated construction, the heating element 138 is a combustor having a body 142 that is coupled (e.g., releasably coupled) to the upper end 130 of the top drill pipe 38, directly below and adjacent the rotary drill head 54 and coupling 58. In other constructions, the heating element 138 is coupled to the rotary drill head 54, to the coupling 58, to a lower end 146 of the drill tower 14, or to other locations on the drill rig 10 (e.g., anywhere between the air compressor 62 and the drill bit 106). In some constructions, the heating element 138 is movable along the drill pipes 38, such that the heating element 138 may be relocated or repositioned along the drill pipes 38 as desired. In some constructions, the heating element 138 is disposed between the rotary drill head 54 and the drill bit 114.
In the illustrated construction, the heating element 138 is fueled by the same fuel source that is used to fuel the prime mover 102. However, in other constructions the heating element 138 has its own, separate fuel source. In the illustrated construction, the heating element 138 is a combustor that receives and ignites fuel so as to generate heat. The generated heat is directed toward the compressed air that is entering the internal cavity 134. By warming the compressed air, the effective pressure and flowrate of the compressed air is increased, thereby reducing the amount of work and fuel required by the air compressor 62 to generate a continuous airflow into and out of the borehole 114 and to flush material out of the borehole 114. The direct heating of the airflow with the heating element 138 increases the effective pressure and flow rate of the airflow more efficiently than with the mechanical air compressor 62 alone. This allows the size of the air compressor 62 to be decreased, if desired, also resulting in a net decrease in fuel required for generating the flushing air stream.
While the illustrated heating element 138 is a combustor, in some constructions the heating element 138 is an electrical heating element, an air-to-air heat exchanger using diesel engine exhaust heat, a concentrated solar heater, or any other heating element. Additionally, while the heating element 138 is illustrated at the upper end 130 of a top drill pipe 38, in some constructions the heating element 138 is located at other locations. For example, in constructions where the heating element 138 is an air to air heat exchanger utilizing waste exhaust heat, the heating element 138 may be located in close proximity to a diesel engine. In such a construction, an air line from the heating element 138 to the upper end 130 of the top drill pipe 38 may be insulated to retain the heat until it was used. In constructions where the heating element 138 is an electric heater, the heating element 138 may be located in the same location as the combustor heating element 138 in
As noted above, it can be advantageous to also use the compressed air to cool the drill bit 106. Therefore, in the illustrated construction the heating element 138 is disposed well above the drill bit 106 (i.e., at the upper end 130 of the top drill pipe 38). In this construction the warming of the compressed air occurs where the air enters the top drill pipe 38, so that the compressed air is at its coolest point where it reaches the drill bit 106. However, in other constructions the heating element 138 is located closer to the drill bit 106 (e.g., even down within the borehole 114). In some constructions, the drill rig 10 includes a plurality of heating elements 138 (e.g., one disposed above the borehole 114 along the drill pipes 38 and another disposed within the borehole 114 along the drill pipes 38).
The direct heating of the airflow with the heating element 138 provides a robust and inexpensive design for effectively heating airflow used to flush material out of the borehole 114. In some constructions, the heating element 138 is easily coupled to existing drills as a retrofit, or is alternatively provided as a component of a newly manufactured drill rig.
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With continued reference to
With continued reference to
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.
This application claims priority to U.S. Provisional Application No. 62/206,458, filed Aug. 18, 2015, the entire contents of which are incorporated herein by reference.
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