US 3775805 A
Method and apparatus for clearing solid material from elongate hollow structures, e.g. solidified catalyst filled tubes of a reformer, comprises inserting into the hollow structure a drill bit connected to a drive motor by a hollow drill stem, operating the motor to rotate the bit and break up the material and simultaneously withdrawing broken up material by the application of sub-atmospheric pressure to the interior of the drill stem which is in communication with the interior of the hollow structure via apertures in the drill bit body.
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United States Patent [191 A Mitchell et al.
[111 7 3,775,805 a Dec. 4, 1973 CLEARING SOLID MATERIAL FROM ELONGATE TUBES AND PASSAGES Inventors: David Thomas Somerled Mitchell,
Norwich; Henry Roy Francis Melsom, Gorlestone, both of England Assignee: Hunting Oilfield Services Limited Filed: July 23, 1971 Appl. No.: 165,520
Foreign Application Priority Data Mar. 12, 1971 Great Britain 6,715/71 US. Cl 15/304, 15/385, 175/213 Int. Cl A471 5/38 Field of Search v175/213, 215;
7 References Cited UNITED STATES PATENTS 12/1923 Easterday 15/304 X ExHAgs Kunnemanmf. 175/213 X Fuller 15/304 X Primary Examiner-Harvey C. Hornsby Assistant Examiner-C. K. Moore Attorney-Frederick E. l-lane et al.
11 Claims, 6 Drawing Figures AIR 7U 26/ 78 MOTOR 74 0 EATENTEDBEII 419 s SHEET Q U? 4,
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ATTORNEYS NTORS l CLEARING SOLID MATERIAL FROM ELONGATE TUBES AND PASSAGES The present invention concerns improvements in and relating to a method of and apparatus for removing solid material from the interior of hollow structures, such for example as pipes of other passages.
The invention has particular but not exclusive application to the removal of solid material from open ended tubes which have to be cleared out in situ, such for example as reformer tubes filled with catalyst pellets which have solidified during use of the reformer.
On certain designs of reformers, a nest of vertically positioned tubes are filled with catalyst material in pellet form. Over a period of time the catalyst agglomerates and becomes cement-like in consistency. These tubes may be about 4 inches in diameter and 40 feet long and may not be easily removed from the reformer for reasons of economy.
I-leretofor these tubes have been cleared by breaking up the catalyst manually using a steel bar and removing the broken up material at intervals with a suction hose. Since this method depends on the manual dexterity and skill of the workman wielding the steel bar, there is a high possibility of damage to the tube during the clearing operation. Furthermore, the method is very timeconsuming; for example, only about eight to ten tubes can be cleared in a 24 hour day. For a reformer having 200 tubes, whosetubes have to be cleared about every six months, the clearing operation takes about four weeks (working 24 hours a day), during which time the reformer is, of course, inoperative.
It is an object of the invention to provide an improved method of and apparatus for removing solid material from hollow elongate structures.
According to one aspect of the present invention there is provided apparatus for breaking up and removing solid material from the interior of an elongate hollow structure, the apparatus comprising:
elongate tubular stem means having a longitudinal axis and defining an interior space;
a cutting means for breaking up said material mounted at one end of said stem means;
drive means for rotating said stem means and said cutting means about said axis;
mounting means for locating said stem means and said cutting means relative to said hollow structure substantially coaxially therewith and in a manner to permit axial movement of said stem means relative to said hollow structure; and
means for withdrawing broken up material from the interior of said hollow structure through said interior space of said stem means.
According to another aspect of the present invention there is provided a method of breaking up and removing solid material from. the interior of an elongate hollow structure using a rotatable cutting means connected to angular drive means by elongate tubular stem means comprising inserting said cutting means into said interior of said hollow structure, locating said cutting means and stem means relative to said interior of said hollow structure substantially coaxially therewith so as to allow axial movement of said cutting means, operating said drive means to rotate said cutting means to break up said material and simultaneously with operation of said drive means withdrawing said broken up material from said interior of said hollow structure through the interior of said stem means.
Using the present invention for clearing reformer tubes, it has been found that a 200 tube reformer can be cleared out in under 4 days, working in the day only. This presents a considerable saving in time and corresponding increase in the operational time of the reformer. Furthermore, since the clearing operation can be substantially automatic the possibility of damaging the-tube walls is very considerably reduced.
Further features and advantages of the present invention will become apparent from the following description of an embodiment thereof, for clearing tubes, given by way of example only, with reference to the accompanying drawings, in which:
FIG. 1 is a diagram of a drilling assembly in accordance with the invention in operation;
FIG. 2 is a diagram of a drill string section, used in the assembly;
FIG. 3 is a section through the drill string and drive therefor of the embodiment of FIG. 1, but with a modified drill bit;.and
FIGS. 4, 5 and 6 are perspective views of a tool for assembling the drill string.
The apparatus shown in FIGS. 1 to 3 of the drawings comprises a drill which is adapted to drill out solid material from a tube. The drill comprises a bit mounted on a tubular stem and which is provided with one or more apertures for the removal of spoil through the interior of the stem. A source of subatmospheric pressure is connected to the interior of the stem to withdraw spoil up through the stem.
A drive unit for the drill is secured relative to the pipe in use and includes a rotary coupling which couples a rotary drive to the drill stem while permitting axial movement of the drill and also locates the drill stem radially of thepipe substantially coaxially thereof. In the preferred embodiment, the coupling is of the Kelly" type in which the drill stem includes a Kelly which is a tube having a square outer section, mating with a bushing of similar square internal section to which drive torque is applied.
The Kelly has a screw-threaded end to which a drill bit or a drill string, comprising one or more extension sections are screwed.
The bit of the drill may be designed to crush and pulverise the solid material and this facilitates extraction of the spoil through the drill stem. However, in some circumstances it is sufficient for the bit to cut or break up the material into nuggets.
Referring now to the drawings in more detail, a catalyst tube is shown at 10, choked with solid catalyst material 12. The tube has a flange 14 at its upper end, to which a casing 16 of a drive unit is secured, for example by means of bolts 18.
The drive unit casing 16 contains a rotary bushing 20 which is secured co-axially with the catalyst tube 10 and is coupled by, for example, a chain wheel 22, chain 24 and sprocket wheel (not shown) to a pneumatically operated drive motor 26. An air supply line 28 supplies air under pressure to drive the motor 26 and the line 28 includes a manually operable valve 30 for controlling the speed of the motor 26 and a lubricator 32, upstream of the valve 30, by which the motor 26 is lubricated. The motor 26 may be provided with output gearing (not shown). Alternatively, an electric and other motor may be used to drive the bushing 20 through a chain or belt drive or a gear train.
The upper surface of the drive bushing 20 is provided with radial slots 34 which co-operate with corresponding radial projections 36 on the lower surface of a Kelly bushing 38, so as to impart rotary drive to the Kelly bushing 38, and also locate the Kelly bushing co-axially with the drive bushing 20 and hence with the catalyst tube 10. The Kelly 40 extends through the Kelly bushing 38, the square sections of the Kelly 40 and Kelly bushing 38 co-operating to transmit drive torque to the Kelly 40, which is located co-axially with the catalyst tube 10.
Lifting tackle (not shown) enables the Kelly 40 to be raised until a flange 42 on its lower end lifts the Kelly bushing 38 clear of the drive bushing 20 and enables a drill string to be attached to the screw thread on the lower end of the Kelly. The drill string comprises a bit 44 and a number of hollow pipe sections 46, one of which is shown in more detail in FIG. 2 of the drawings.
The section 46 comprises a frusto conical female thread 46d at its upper end and a frusto conical male thread 46a' at its lower end. It is also provided with a flange 46b adjacent each end by which it may be raised and lowered; the flanges 46b are provided with radial slots 46c on their lower surfaces for a purpose to be hereafter explained. The flanges 46b each form a device known as a stabiliser, and assist in maintaining the bit 44 centrally in the catalyst tube 10.
The bit 44 is attached either to the lower end of the lowermost section of the drill string or directly to the Kelly. The bit 44 shown in FIG. 1 is designed so as to crush and pulverise the catalyst material 12 and has a diameter closely approaching the inside diameter of the catalyst tube 10. Apertures 48 in the bit body adjacent the bit 44 provide communication between the exterior and interior of the drill string through which spoil may be drawn into the interior of the drill string and re moved by suction applied to the upper end of the drill string, air being drawn into the tube at the lower end of the drive bushing 20. To this end the upper end of the Kelly 40 is connected through a swivel coupling 50, which provides a sufficiently air-tight rotary coupling, and a flexible hose 52 to a suction device (not shown), for example a venturi device or vacuum pump.
In a modification, shown in FIG. 3, a drag bit 44' is used together with an eccentrically mounted crushing cam 58 whose radially outermost surface portion is arranged to be close to the wall of the tube 10. The catalyst 12 which has been broken up by the bit 44 is crushed by the cam 58 and then drawn by suction into the interior of the drill string through one or more apertures 48 in the bit body. The bit body is provided with stabilising centering flanges 60.
In operation, the drive unit 16 is secured to the flange 14 at the top of the catalyst tube 10, as shown in FIG. 1. The bit 44 or 44' is attached to the lower end of the Kelly 40 and the swivel coupling 50 attached to the upper end of the Kelly. The bit is then inserted through the drive bushing into the tube 10 until it engages the top of the catalyst 12, and the Kelly bushing 38 is drivingly engaged with the drive bushing 20. The suction device is actuated and the drive motor 22 started and drilling continues until an upper flange 54 of the Kelly 40 engages the Kelly bushing 38. The drive motor 22 is then stopped, the Kelly raised by a handle 56 on the swivel coupling 50 until the bit is clear of the drive bushing 20. A section is then inserted between the bit and the Kelly 40 and the bit and section are lowered. The drilling operation is then continued, further sections being added as required.
To add to or remove sections from the drill string a single tool 68 is employed which replaces the three tools, the elevator, the slips and the tong, conventionally used. This tool isshown in FIGS. 4 to 6 and comprises a generally U-shaped body 70 shaped to partly encircle a section 46 and flange 46b. The inner surface 72 of the U is stepped at 74, the lower surface of a section flange 46b seating on the step. The body 70 is provided with portions 76 which project onto the step 74 and which have the same angular spacing as the slots 46:; in the section flanges 46b. These portions are designed to engage in the slots 460 to locate the tool angularly relative to a section 46.
There is provided in the external surface of the body 70 a slot 78 and the lower surface 70 of the body is stepped at 80 so as to seat in the top of the drive bushing 20.
The tool is provided with a handle 82 pivotally mounted on the body 70.
To add a section to the drill string, the Kelly and Kelly bushing are lifted until the upper flange 46b of the first section 46 connected thereto is clear of the drive bushing. The tool 68 is then engaged around the section below the upper flange and seated on the drive bushing 20. The tool is angularly locked relative to the drive unit casing 16 by pivoting three locking members 84 (only two of which are shown), pivotally mounted on the casing 16 respectively, into the slot 78 and into engagement with the end faces 86 of the tool body, as shown in FIG. 5. The Kelly is then lowered slightly to engage the flange 46b of the section 46 in the tool and the portions 76 in the slots 460. This section is thus supported and angularly located by the tool.
The Kelly is then unscrewed from this section and a second section screwed in its place. The flange 46b at the upper end of this second section is engaged by a second identical tool 68, as shown in FIG. 6, and the string supported therefrom by the handle 82. The first tool is disengaged from the first section with slight lifting of the string and the string is lowered until the second tool seats on the drive bushing 20. This second tool is then locked to the casing by the locking members 84 while the Kelly is screwed into the second section. Finally the second tool is removed and the string lowered until the bit contacts the catalyst material.
The above sequence is reversed for removal of sections from the string.
In the process described above, with the catalyst tubes 10 disposed vertically, the pressure on the bit is provided by the weight of the drill string. If desired, a thrust bearing (not shown) may' be provided at the end of the Kelly 40 and a hydraulic or pneumatic ram or similar device used to provide additional pressure on the bit. With this modification, the drilling assembly shown in the drawings can also be used to clear horizontal or inclined tubes or passageways, the ram or similar device providing the required pressure on the bit.
While the invention has been described in relation to clearing tubes, it is equally applicable to clearing out any elongate hollow structure.
1. Apparatus for breaking up and removing solid material from the interior of an elongate hollow structure, the apparatus comprising:
elongate tubular stern means having a longitudinal axis and defining an interior space;
cutting means for breaking up said material and mounted at an end of said stem means;
drive means for rotating said stem means and said cutting means about said axis arranged to permit axial movement of said stem means relative thereto;
mounting means supporting said drive means for mounting said drive means on said hollow structure and arranged to be mounted on an end of said hollow' structure so as to locate said stem means relative to said hollow structure substantially coaxially therewith and in a manner permitting axial movement of said stem means relative to said drive means and said hollow structure; and
means for withdrawing broken up material from the interior of said hollow structure through said interior space of said stem means.
2. Apparatus according to claim 1 wherein said withdrawing means includes a source of sub-atmospheric pressure fluid adapted to be connected to the other end of said stem means.
3. Apparatus according to claim 2 wherein said cutting means includes a body defining an interior space in communication with said interior space of said stem means and aperture means connecting said interior space of said body to the exterior thereof.
4. Apparatus according to claim 3 wherein said cutting means includes a drill bit and an eccentrically mounted cam member located between the cutting portion of the drill bit and said aperture means, the maximum dimension of said cam member from said axis being substantially equal to the internal radius of said hollow structure.
5. Apparatus according to claim 1 wherein said cutting means is a drill bit having a maximum diameter substantially equal to the internal diameter of said hollow structure.
6. Apparatus for breaking up and removing solid material from the interior of an elongate hollow structure, the apparatus comprising:
elongate tubular stem means having a longitudinal axis, defining an interior space and including a first stem section having a polygonal external periphery; cutting means for breaking up said material and I mounted at an end of said stem means;
drive means for rotating said stem means about said axis and including an annular rotatable bushing having a polygonal internal periphery correspondmeans for withdrawing broken-up material from the interior of said hollow structure through said interior space of said stem means.
7. Apparatus according to claim 6 wherein said stem means includes at least one second stem section connected between said first stem section and said cutting means.
8. Apparatus according to claim 7 including tool means for connecting and disconnecting said second stem section and said first stem section comprising a generally U-shaped body for partly encircling said second stem section adjacent one end thereof, first locating means on said body for locating said body angularly relative to said second section, means on said body for facilitating suspension thereof, and second locating means on said body for locating said body angularly relative to said drive means.
9. Apparatus according to claim 8 wherein each second stem section includes a flange adjacent each end defining recess means and said first locating means includes projection means for engaging in said recess means.
10. Apparatus according to claim 8 including a casing for said drive means and locking means on said casing, said second locating means including recess means for engagement by said locking means.
11. Apparatus according to claim 6 including a casing for said drivemeans, and said mounting .means forming a part of said casing for attachment to said hollow structure.
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