US3045766A - Suspension type rotary piercing process and apparatus - Google Patents

Description

July 24, 1962 D. H FLEMING, JR 3,

SUSPENSION TYPE ROTARY PIERCING PROCESS AND APPARATUS Filed Aug. 22, 1958 Fuel Air &

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T NEY ite 3,M5,7% Patented July 24, 1962 This invention relates to an improved method and apparatus for thermally piercing holes in mineral and mineral-like materials.

The term suspension type blowpipe as used hereinafter applies to a freely suspended non-rotating blowpipe provided with a combustion chamber and an axial flame nozzle. Kerosene and oxygen are combusted in the combustion chamber and the products of combustion are discharged through the nozzle. The depth of hole that can be pierced by a suspension type blowpipe is limited essentially by the length of the supporting cable and the supply hose which follows the blowpipe down the hole.

The term rotary blowpipe as used hereinafter applies to a blowpipe which rotates as a whole. The depth of hole is limited by the length of the rotary blowpipe itself.

One of the problems involved in the deep drilling of holes in rock-like mineral formations is the piercing of hard, consolidated, non-spallable strata, as well as unconsolidated spallable rook (such as broken rock conditions encountered from prior blasting). The conventional suspension type blowpipe has been found to operate satisfactorily on consolidated spallable rock formations such as those generally found in granite quarries. As it is fed into a hole, the high velocity flame of the blowpipe spalls off particles of rock, hurls the rock cuttings away from the flame and starts the cuttings on their way out of the hole. Cooling water for the blowpipe discharged radially into the hole at the lower end of the blowpipe, is transformed by the heat of the products of combustion and rock particles into steam, which together with combustion pro-ducts provides the medium for carrying the cuttings out of the hole. For rock formations having unconsolidated areas or non-spallable strata, there is a tendency for the material to form an obstruction, sometimes referred to as a collar or a plug, and thereby retard the advance of the suspension blowpipe. It has been found that with a rotary blowpipe such obstructions may be overcome. However, the rotary blowpipe is only practical for shallow holes.

It is, therefore, an important object of the present invention to provide a novel, thermal-piercing blowpipe of the suspension type having a rotatable burner .nozzle and adapted to pierce deep holes in normally spallable rocklike materials where non-spallable and unconsolidated formations occur.

Another important object of the present invention is to provide a novel thermal-piercing blowpipe of the suspension type having a burner nozzle which is rotatable with respect to the blowpipe body and the suspension means, and adapted to provide earth material removing flames for forming a hole which is larger in diameter than the blowpipe and for minimizing the occurrence of and overcoming restrictions in the hole. Another object is the provision of a self contained power unit for rotatably driving the blowpipe burner. Another object is the provision in the rotary burner of an axial flame discharge nozzle and at least one flame discharge nozzle disposed to direct supersonic flames against the sides of the hole ahead of the blowpipe ath in order to cut clearance for the advance of the blowpipe and create a backwash effect to aid in removing the cuttings from the flame region. Another object is the provision of water cooling passages in the rotary burner in which the water is discharged radially outwardly or rearwadly to direct the water discharge away from the flame area in the blowpipe path.

Another object of the invention is to provide an improved method for thermally piercing relatively deep holes in rock like material which permits the main body of the blowpipe and its suspension and supply conduits to remain non-rotating while the burner parts rotate to produce a hole of desired diameter, characterized by a minimum occurrence of collars, plugs or other obstructions.

Other objects, features and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment of the invention taken in conjunction with the drawings in which:

FIG. 1 is a section of a rockface illustrating the operation of a blowpipe apparatus embodying the principles of the present invention;

FIG. 2 is an enlarged sectional elevation view of the blowpipe shown in FIG. 1;

FIG. 3 is an enlarged diagrammatic illustration of a gear train arrangement in the gear reducer box 54 shown in FIG. 2; and

FIG. 4 is an enlarged view of a modification of the burner shown in FIG. 2.

In accordance with the invention there is provided a novel method and apparatus for thermally piercing a hole in a mass of mineral-like material. The method of the invention comprises directing the flames from a blowpipe axially downwardly and angularly outwardly at a temperature and velocity sufficient to spall the mineraL like material in its path to form a hole, the diameter of which is larger than the external diameter of the blowpipe, affording clearance for blowpipe advance, and thrust the cuttings away from the cavity formed thereby. Cooling water, which flows through the blowpipe and is discharged radially into the hole at the burner end of the blowpipe, is formed into steam and serves with products of combustion as a carrying medium for speedily removing the cuttings out of the blowpipe hole. Thus, as the blowpipe is fed into the hole, the mineral material about the flame end is quickly spalled and the force of the flame and steam carries the spalled particles out of the hole.

Shown in FIG. 1 is a blowpipe ltl illustrating a preferred embodiment of the invention, which blowpipe can be suspendedly lowered into a hole in a rock formation R by means of a cable and winch apparatus. Referring to FIG. 2, the blowpipe it) comprises at its upper end an elongated tubular casing or housing wall 12 such as steel or other similarly high strength material of a length to provide the necessary guidance to maintain a straight hole, and adjacent its lower end a burner driving means 13. Fuel and oxidant are supplied respectively in a fuel line F and an oxidant line 0 which extend through the casing top and terminate at a process tube 14. The process tube 14 extends axially through the driving means 13 and is supportably mounted in fixed relation to the casing. For example, the tube 14- is fixed to the top of sleeve 24 as at A, and the sleeve 24 is fixed to the casing '12 as by a spider B.

Conduit means are provided in the process tube 14 to separately conduct the oxidant and fuel to a burner 16. For this purpose the process tube 14 is provided with an axially positioned fuel pipe 1 8, defining central passageway 20 and annular passageway 22. Suitable connections at the upper end of the driving means 13 join passageways 2t) and 22 to lines F and O for the concurrent but separate passage of fluid fuel and combustion supporting material, respectively.

Preferably, the fluid fuel is kerosene and the oxidizing agent is gaseous oxygen; but other fuels and oxidants may be employed if so desired.

Cooling water is supplied by a flexible hose W connected to the casing top, the water flowing through a water jacket formed between the sleeve 24 and adjacent portions of the blowpipe casing 12 and extending the length of the sleeve.

Fitted on the lower end of the fuel tube 18 is an injector 26 provided with a central bore 28 in communication with the fluid fuel in pipe 18 for the delivery of the fluid fuel through radial injector orifice openings 30. In assembly, the injector 26 is disposed in stationary relation to the casing 12 and fuel pipe 18 and extends into the entrance bore of the burner 16 and forms therewith an entrance passage 32 through which the oxygen in the annular oxygen passage 22 may flow. In this manner the fuel and oxygen mix intimately in passing through the burner entrance 32 and burn vigorously in the combustion chamber 34.

The combustion gases exhaust through multiple ports comprising an axial nozzle (not shown) and angularly disposed nozzles 36 in burner tip 38 to give intense supersonic rocket-type flames. These flames impinge against or wipe the sides of the hole, causing spalling of the rock formation. The backwash of the flame tends to travel upwardly in the flame region along the sides of the hole and into the clearance space around the end of the blowpipe casing to hurl the rock cuttings and chips away from the burner tip and aid in restricting the occurrence of collars and plugs.

The cooling water fills the water jacket space outside of the sleeve 24 and inside the length of the blowpipe casing 12, and passes through cooling passages 40 in the wall of the combustion chamber 34 to an annular channel 41 from which it flows through cooling passages 42 in the burner tip 38. The water in the cooling passage is discharged radially from the burner tip into the rearwardly moving flame backwash where the water spray is converted into steam. The water is also converted into steam by contact with the heated rock particles.

'In accordance with the present invention, provision is made for improving the thermal piercing properties of the suspension type blowpipe 10 in consolidated spallable rock formations or rock formations with broken and nonspallable strata, by rotating the blowpipe flame without limiting or reducing the working depth of the blowpipe. This is accomplished by providing power means within the confines of the blowpipe casing 12 for rotating the burner 16. The invention will be described in terms of a blowpipe having eletcrical means for rotating the burner 16, although it is to be understood that the invention is susceptible of adaptation with other power means of rotation, such as water power or air power means.

Referring to FIG. 2, there is shown driving means 13 comprising a hollow driver shaft 44 and a hollow driven shaft 46 in longitudinally spaced and linearly aligned relation to each other and concentrically disposed about the process tube 14. Both the driver shaft 44 which is positioned about the upper half of the tube 1 4, and the driven shaft 46, are adapted to be rotatably moved about the axis of the blowpipe.

Power is supplied to the driver shaft 44 by electric motor rotating means preferably of the alternating current induction type comprising an annular stator '48 suitably mounted in the sleeve 24 which in turn is supported concentrically in fixed relation to the casing wall 12 and an annular rotatable rotor 50' disposed concentrically within the stator 48 and lockingly keyed to the driver shaft 44. Electric power is supplied to the stator by a suitably insulated cable 52. The rotating speed of the driver shaft 44 is preferably reduced by means of a gear reducer box 54 supported within the lower part of sleeve 24. Referring to FIG. 3, the gear reducer box 54 comprises a suitable gear train, for example, a compound epicyclic gear train having a stationary circumferential or ring gear 58 securely mounted on the inside wall surface of the water jacket 24, a central or sun gear 60 attached to the outer surface of the driver shaft 44 and adapted to rotate therewith, and two or more planetary spur gears 62 disposed in meshing relation with said ring gear and sun gear and suitably constrained to move bodily at a reduced speed around the circumference of the sun gear 60. Compound gears 64 mounted on the axes of the planeatry gears 62 transmit reduced rotary motion to a compound ring gear 66 which slowly rotates relative to compound gears 64. A spider 68 attached to the ring gear 66 transmits this reduced speed rotary motion through a suitable coupling 70 to the driven shaft 46. The driven shaft 46, in turn, is suitably secured to the upper part of the burner 16. With this construction the drive shafts 44, 46 and the burner 16 are rotated as a unit relative to the stationary parts 12, 14 and 18 of the blowpipe. Suitable bearings (not shown) are provided on the spider 68 and the shaft 46. A suitable bearing 72 is provided between the lower end of the tube 14 and the inlet bore of the burner.

Since the burner rotates within the lower end of the casing 12, the burner body 16 has a close fit to the wall of casing 12 above the annular channel 41 and the burner tip 38 has a rotary sliding and water sealing fit to the wall of the casing 12. Preferably annular sealing means may be provided between the relatively rotating surfaces such as one or more 0 rings 74 of suitable compressible material.

In the preferred practice of the invention a driver shaft speed of approximately 3000 rpm. and a burner speed of approximately 25 rpm. is admirably suited to thermal piercing of substantially all types of spallable rock formations, although higher or lower rotating speeds may be employed if so desired.

In operation, as the blowpipe is lowered into the hole H, the angled flames of the blowpipe burner spall off rock particles at the bottom and sides of the hole, thereby continuously providing a clearance cut for the further lowering of the blowpipe. When a fissure is encountered, the rotary movement of the burner element is sufficient to reduce the occurrence of obstruction.

Suspension type blowpipes made in accordance with the principles of the invention make possible the thermal piercing through unconsolidated rock formations at drilling speeds substantially higher than present day drilling speeds with practically no limitation on the depth of hole.

An important advantage of the present invention is the utilization of the weight of the blowpipe to improve control of the rate of lowering the blowpipe. In lightweignt blowpipes the pressure of the gases exiting inside the bore hole at the lower end of the blowpipe tends to drive the blowpipe upwardly in much the same manner as a piston is driven in a cylinder. This so-called piston effect is overcome in the present invention by extending the length of the blowpipe sufficient to provide the additional weight necessary to at least equal the piston effect. The provision of a substantial casing wall thickness and a large body of water in the upper part of the casing 12 contributes greatly to the weight in operation.

The minimum weight for large jet piercing blowpipes can be approximately determined by the following empirical formula:

W= /zPA where:

W=minimum weight, lbs.

P=gas pressure inside the bore hole, p.s.i.

A=circular cross sectional area of the blowpipe casing,

sq. in.

For example, a 5 inch blowpipe should have a minimum weight calculated to be approximately 635 lbs. Preferably the weight of the larger jet piercing blowpipes having casing diameters of approximately 5 inches or larger should be between 700 and 1000 lbs. For smaller blowpipes, such as a 2% inch blowpipe, the preferred weight is approximately pounds.

The modification shown in FIG. 4 shows an alternative arrangement for discharging the cooling water into the backwash of the burner flames, wherein the discharged cooling water from a rotary burner 16a exits angularly backwardly :from cooling passage 42a. In this manner the cooling water flows more in the general direction of the rearwardly moving flame backwash and the possibility of water entering the flame area is substantially avoided. Rearward discharge of the cooling water may be at any angle up to 45 from the horizontal, angles up to being preferred. Stated differently, the angular discharge of quenching fluid may vary between 90 and 135; measured from the vertical axis of the blowpipe, and preferably between 90 and 105 In order to indicate the advantages of the present invention, the following table set-s forth the results of typical piercing procedures made with a 5 /2" diameter blowpipe wherein the direction of spray from the rotary burner of the invention was changed from measured downwardly from the horizontal, to between 0 and 5 above the horizontal. In these tests the material pierced was taconite of the type which is poorly spalla'ble and not amenable to piercing procedures. The burner chamber pressure was maintained by a constant displacement pump at approximately 65 psi. The rotor and burner speeds were 3600 r.p.m.s and 25 r.p.m.s respectively.

The above table indicates the greatly improved piercing rate of a suspension type blowpipe having a rotatable burner resulting from discharging the cooling water from the burner radially outward or angularly backward, the improvement in depth of hole and piercing rate being approximately 100%.

From the above description it will, therefore, be seen that the present invention provides a novel suspensiontype rotary flame piercing process and apparatus for facilitating the deep drilling of holes in rock-like spallable bodies with unconsolidated and non-spallable strata. A noteworthy feature of the invention is that the major portion of the blowpipe, including the casing, does not rotate, the principal rotating part being the burner element providing flames feerly rotatable so that a hole of desired diameter larger than the blowpipe is pierced. This is to be distinguished from the conventional rotary type thermal piercing blowpipe wherein a power driven rotating table above ground drives a gear fixed to the outside casing of the blowpipe, and the entire blowpipe assembly rotates.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the invention.

What is claimed is:

1. In combinaiton with a blowpipe having a casing with an open lower end and provided at its upper end with a hoisting cable connection whereby it is adapted to be suspended by a cable and lowered thereby into an elongated vertical passage thermally pierced into a mineral body as said passage increases in length, flexible hoses with hose connections at the upper end of said blowpipe forming supply conduits for oxidizing gas and fuel, a rotatable flame burner mounted in the lower end of said casing for rotation with respect to said casing, means for conducting oxidant and fuel from said hose connections to said rotatable flame burner, means for circulating fluid coolant through said blowpipe and discharging said coolant adjacent the forward end of said burner, means for directing jets of flame from said rotable burner out of said open lower end and means located within the confines of said casing above said rota-table flame burner for rotating said flame burner with respect to said casing.

2. A blowpipe comprising a cable suspended elongated blowpipe casing, a fuel conduit and an oxidant conduit extending into said casing and disposed in fixed relation thereto, a relatively rotatable burner, means for mounting said burner inside said casing for rotation inside said casing and relative to said fixed conduits, said relatively rotatable burner having an entrance bore in receiving relation to said conduits, a nozzle for the discharge of flames from said burner, said casing having an open lower end through which said nozzle extends, means for rotating said burner, and means for circulating fluid coolant through said blowpipe and discharging said coolant adjacent the forward end of said burner.

3. A blowpipe for thermally piercing an elongated hole in a mineral body comprising an elongated housing having therewithin axially disposed fuel and oxygen carrying tubes, said housing having an open lower end, a water cooled burner in communication with said tubes, means for supplying cooling water to said burner, means for circulating cooling water through said blowpipe and burner and discharging said water adjacent the forward end of said burner, power means for rotating said burner relative to said housing and said tubes, and means for discharging rock piercing flame from said burner out of said open lower end.

4. A blowpipe as claimed in claim 2 in combination with a fuel injector stationarily mounted in said casing and disposed in said rotary entrance bore and forming therewith a passage for mixing fuel and oxidant in transit in said rotary entrance bore.

5. In combination with a blowpipe having an elongated casing and supply conduits and suspension means therefor, a rotatable flame burner mounted in the lower end of said casing for rotation therein relative to said casing, said burner having at least one angled flame nozzle, and said casing having an open lower end through which said nozzle extends for directing supersonic flames in advance of and along the sides of a hole to be thermally pierced, the inside of said casing and the outside of said rotary burner forming therebetween a water jacket, means in said blowpipe for supplying cooling water to said jacket, cooling water passages in said burner having entrances opening into said jacket and receiving water therefrom and so disposed as to discharge a water spray away from flames emanating from said flame nozzles and means for rotating said burner 6. A blowpipe construction for piercing a deep hole in rock-like material comprising a cable-suspended blowpipe casing having an open lower end, a rotatable flame burner in the lower end of said casing and extending below said open end and provided with a flame discharge nozzle angled forwardly with respect to the blowpipe axis to rotate therearound relative to said casing, cooling water passages disposed in said burner so as to discharge a water spray from the lower end of said burner at an angle of at least measured upwardly from the axis of the blowpipe means for rotating said burner, and means for supplying cooling water to said water passages in said burner.

7. A suspension type blowpipe for thermally piercing an elongated hole in a mineral body comprising a housing having stationarily mounted therewithin fuel and oxidant carrying tubes, a relatively rotatable burner in fuel and oxidant receiving relation to said tubes, drive means disposed entirely within said housing for rotating said burner relatively to said tubes and said housing, said housing having an open lower end, a plurality of nozzles in said burner extending below said open lower end for discharging combustion products therefrom at a velocity and temperature sufficient to cause spalling of the mineral body, means for cooling said burner with water, means for supplying water to said cooling means, and

means for discharging the water behind said nozzles in the vicinity of the combustion products.

8. A suspension-type blowpipe for thermally piercing an elongated hole in a mineral body comprising an elongated housing provided at its upper end with raising and lowering means and having therewithin a pair of elongated axially disposed tubes, a water-cooled burner element disposed in access with the lower ends of said tubes and rotatively mounted in the bottom of said housing, means for supplying cooling Water to said burner element, power means inside said housing for imparting rotary movement to said burner element, said housing having an open lower end, and passage means in said burner element extending below said open end for discharging fiame and water from said burner element during rotation thereof.

9. Apparatus for thermally piercing a deep hole in a mineral body comprising an elongated blowpipe casing having an open lower end, a hollow process tube mounted within said casing, a burner element rotatably mounted in said casing below said process tube, means for rotatively moving said burner element with respect to said process tube, a fuel gas passage line in said process tube, the space in said process tube around said fuel passage line constituting a conduit for the fiow of oxygen gas, ejector means between said burner element and said process tube for effecting mixing and combustion of said gases in said burner element, a plurality of nozzles in said burner element extending below said open end for projecting a rock-piercing flame from the lower end of said casing, said casing and burner forming a water jacket surrounding said nozzle and discharge orifices from said water jacket for conversion of the water in said water jacket to steam, whereby the occurrence of restrictions in the hole is substantially reduced and the removal of such restrictions is facilitated.

10. A blowpipe according to claim 1, said blowpipe having a weight at least equal to half the force of the gas pressure at the bottom of the hole acting against said blowpipe.

11. A blowpipe according to claim 5, said cooling water passages being disposed to discharge a water spray at an angle between 90 and 135 measured upwardly from the axis of the blowpipe.

12. A blowpipe according to claim 5, said cooling Water passages being disposed at an angle between and measured upwardly from the axis of the blowpipe.

13. In combination a high speed, hollow, rotary, driver shaft, a gear reducer connected with said driver shaft, a low speed, hollow, rotary, driven shaft coupled to said gear reducer and rotatably driven by said driver shaft through said gear reducer, a pair of concentrically disposed pipes extending within and through said shafts and said gear reducer and defining a central fuel passage and an annular concentric oxidant passageway, means forming a combustion chamber having an entrance bore gastightly secured to said driven shaft and rotatable therewith and provided at one end with a passage for discharging products of combustion, and an injector tube located at the end of said fuel passage and communicating therewith, said injector being stationarily mounted in said entrance bore and forming therewith a passage in communication with said oxidant passage for mixing fuel and oxidant in said entrance bore for discharge into said combustion chamber communicating therewith, means for cooling said combustion chamber, and means for supplying cooling fluid to said cooling means.

14. The combination according to claim 13, said gear reducer comprising a compound epicyclic gear train.

References Cited in the file of this patent UNITED STATES PATENTS Re. 24,603 Atchison et al. Feb. 17, 1959 2,548,463 Blood Apr. 10, 1951 2,675,994 Smith et al. Apr. 20, 1954 2,693,937 Wyland Nov. 9, 1954 2,738,162 Aitchison Mar. 13, 1956 2,794,620 Arnold et a1 June 4, 1957 2,822,148 Murray Feb. 4, 1958 OTHER REFERENCES What are the Russians Doing In Oil Drilling and Production), vol. 56, No. 21, Oil and Gas Journal, May 26,

Fire Chisel, by V. Rabinovich, article in Tekhnika Molodezhi, XXV, 8 (1957), p. 26.

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