EP1043476A2 - Device for pumping slurry - Google Patents

Device for pumping slurry Download PDF

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Publication number
EP1043476A2
EP1043476A2 EP00302089A EP00302089A EP1043476A2 EP 1043476 A2 EP1043476 A2 EP 1043476A2 EP 00302089 A EP00302089 A EP 00302089A EP 00302089 A EP00302089 A EP 00302089A EP 1043476 A2 EP1043476 A2 EP 1043476A2
Authority
EP
European Patent Office
Prior art keywords
pump
screen
slurry
chamber
shafts
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP00302089A
Other languages
German (de)
French (fr)
Other versions
EP1043476A3 (en
Inventor
Gareth David Thomas
Kenneth Ball
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NOV Process and Flow Technologies UK Ltd
Original Assignee
Mono Pumps Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB9908056 priority Critical
Priority to GB9908056A priority patent/GB2348674A/en
Application filed by Mono Pumps Ltd filed Critical Mono Pumps Ltd
Publication of EP1043476A2 publication Critical patent/EP1043476A2/en
Publication of EP1043476A3 publication Critical patent/EP1043476A3/en
Withdrawn legal-status Critical Current

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    • EFIXED CONSTRUCTIONS
    • E21EARTH DRILLING; MINING
    • E21BEARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B21/00Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor
    • E21B21/06Arrangements for treating drilling fluids outside the borehole
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B02CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02CCRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C18/00Disintegrating by knives or other cutting or tearing members which chop material into fragments
    • B02C18/0084Disintegrating by knives or other cutting or tearing members which chop material into fragments specially adapted for disintegrating garbage, waste or sewage
    • B02C18/0092Disintegrating by knives or other cutting or tearing members which chop material into fragments specially adapted for disintegrating garbage, waste or sewage for waste water or for garbage

Abstract

A device for pumping slurry, e.g. mud containing drill cuttings generated during drilling for oil or the like, comprises a generally horizontally disposed macerator having two counter-rotating shafts with alternating cutters and spacers above which is mounted a vertically orientated progressing cavity pump. The spaces in the macerator are axially thicker than the cutting discs so that the macerator will pass particles of a size acceptable to the pump. Impellors horizontally adjacent to the macerator are provided for agitating the slurry to be pumped.

Description

  • The present invention relates to a device for pumping slurry, for example the waste slurry produced by drilling operations.
  • When drilling for oil, the drill cutting head is frequently driven by a mud motor, which is powered by mud pumped down the drill shaft and which returns to the surface up the drilled bore. The mud motor is commonly of the progressing cavity type in which a helical rotor rotates and orbits inside a stator having a helical bore of the same pitch as the stator but one more, or one less, starts. The returning mud or slurry is normally discharged into a tank and contains a large proportion of foreign bodies and tramp materials which settle out in the tank. The foreign bodies in the slurry are of a wide variety, including rock, bits broken from the cutting head, pieces of polymer broken from the stator of the mud motor and often rubbish from the drilling rig such as nuts, bolts and spanners. Once the slurry tank is full it is taken away and used as landfill. For off-shore drilling rigs, the slurry tank is commonly provided on a barge which is taken to a lagoon where the tanks are emptied.
  • Because of the high proportion of hard and abrasive foreign bodies in the slurry it is a particularly difficult medium to pump and it is particularly difficult fully to empty the slurry tank, since the proportion of foreign bodies increases towards the bottom as they settle out. It has been proposed to use a centrifugal pump protected by a static screen for pumping slurry bit this was found to be unsatisfactory.
  • According to the present invention there is provided a device for pumping slurry, the device comprising:
  • a screen adapted to pass only particles of less than a predetermined size and disposed generally horizontally with an inlet in its lower surface and an outlet in its upper surface;
  • a positive displacement pump for pumping said slurry, said pump being disposed above said screen and having an inlet; and
  • chamber connecting the outlet of said screen to the inlet of said pump.
  • A positive displacement pump is one which delivers the same volume of product for each revolution or stroke regardless of pumping speed. A rotodynamic pump, such as a centrifugal pump, requires a certain speed to create the centrifugal effect. It has been found that a positive displacement pump, particularly when operating at a low speed, has less effect on the rheological properties of the slurry and so pumps more efficiently. A centrifugal pump was found to cause the slurry to thicken. The pump is preferably of the progressing cavity, or Moineau, type and may have a single start rotor, with a two start stator.
  • The screen prevents blockages and damage to the pump by rejecting oversize particles. The screen is preferably a macerator, or combined screen and grinder, which reduces those particles which are too large to pass through the pump, rather than simply rejecting them thereby necessitating their removal by other means. In some embodiments however, a simple screen, e.g. a bar or mesh screen may suffice. Such a screen may be static or agitated to prevent blockages.
  • A presently preferred embodiment of the invention consists of a device for pumping slurry, the device comprising:
  • a macerator having a macerating chamber having sidewalls and open upper and lower faces, two parallel, substantially horizontally disposed, shafts extending between opposite sidewalls of said macerating chamber, alternating cutter wheels and spacers disposed on said shafts, said cutter wheels having a greater diameter than said spacers and said cutter wheels on one of said shafts being interleaved with said cutter wheels on the other of said shafts, and means for driving said shafts to counter-rotate;
  • a funnel chamber having upper and lower openings, said lower opening of said funnel chamber being larger than said upper opening thereof and communicating with said open upper face of said macerating chamber; and
  • a pump of the progressing cavity type comprising a helical rotor of N starts and a stator having a helical bore therethrough complimentary to the rotor and having N ± 1 starts, said stator being generally vertically arranged, and said pump having an inlet end in communication with the upper opening of said funnel chamber;
  • whereby in use said pump is operated to pump slurry out of said funnel chamber and thereby draw slurry in through said macerator, and said shafts of said macerator are counter-rotated so as to pass particles of less than a predetermined size and to break up particles of a greater than said predetermined size, said predetermined size being a size acceptable to said pump.
  • The present invention further provides a boom assembly comprising:
  • a swingable boom; and
  • a pumping unit mounted on the distal end of said boom and immersible in a slurry, said pumping unit comprising:
  • a screen adapted to pass only particles of less than a predetermined size and disposed generally horizontally with an inlet in its lower surface and an outlet in its upper surface;
  • a positive displacement pump for pumping said slurry, said pump being disposed above said screen and having an inlet; and
  • chamber connecting the outlet of said screen to the inlet of said pump.
  • Such boom assembly can conveniently used to remove slurry from, e.g., a barge by immersing the pumping unit in the slurry in the barge and sweeping it about to ensure all parts of the barge are reached. The boom assembly can be mounted on a dockside or another vessel as desired.
  • The invention will be described further below with reference to an exemplary embodiment and the accompanying drawings, in which:
  • Figure 1 is a partly cross-sectioned schematic side-view of a first embodiment of the present invention;
  • Figure 2 is a schematic enlarged plan-view of the grinding screen of the first embodiment;
  • Figure 3 is a further enlarged perspective view of part of the counter-rotating shafts of the grinding screen of Figure 2; and
  • Figure 4 is a schematic view of the first embodiment of the invention mounted on a boom.
  • In the drawings, like parts are indicated by like references.
  • Figure 1 shows a pumping device 1 according to a first embodiment of the present invention which is adapted to pump a drill cuttings slurry 3 out of a tank that may be provided on a barge or similar. At the suction end of the pumping device 1, a screening device 4 is provided. This lets through particles 2 in the slurry that are small enough to be pumped by the pumping element 12 and breaks up any larger particles 5. The pumping element 12 is, in this embodiment, of the progressing cavity type with a single-start helical rotor and a two-start helical bore in the stator. It is driven by motor 12a via drive-shaft 12b and pumps slurry from funnel shaped chamber 4a above the grinding screen 4 into the drive-shaft chamber 12c from whence it is discharged via suitable conduits (not shown) to its ultimate destination.
  • Pumping device 1 is also provided with impellors 6 which are disposed adjacent to and on a level with the grinding screen 4. The impellors 6 serve to agitate the drill cuttings slurry and keep the solid particles therein suspended.
  • Figure 1 shows only the grinding screen 4 and impellors 6 submersed in the slurry, however the entire device can optionally be made submersible by provision of appropriate proofing. The pumping device 1 can be provided on the end of a boom or suspended from a crane, so that it can be lowered into the slurry tank and swept across the bottom to remove all of the slurry and foreign bodies.
  • The grinding screen 4 is shown enlarged and from below in Figure 2. As can there be seen, the grinding screen 4 comprises two counter-rotating shafts which are driven to rotate via motor 4b and gears 4c. The shafts are horizontally disposed and extend between side walls of the screen, leaving only two narrow apertures 14 around the outside, and a centre aperture 13 between them. The sense of rotation indicated by arrows in the Figure, is such as to attract particles to the centre aperture 13 rather than the outside apertures 14.
  • Each shaft consists of a series of cutter wheels 9 held apart by cylindrical spacers 10. The spacers 10 are axially thicker than the cutter wheels 9 which are of greater diameter and are interleaved, so as to create gaps 11 through which small solids 2 can pass. Each cutter wheel 9 has at least one tooth 9a and preferably a plurality, e.g. seven as in this embodiment. The size of the gaps 11 will be determined by the size of solids that the pumping element 12 can accept and in a preferred embodiment of the invention is of the order of 8mm axially. Solid particles 5 that are too large to pass through the gaps 11 are broken up by the cutter wheels 9 until they are small enough to pass.
  • Figure 4 shows pumping device 1 mounted on the end of a swingable boom 20 so that it can be lowered into the slurry 3 contained in a barge 30. As the slurry is pumped out of the barge 30, the pumping unit can be lowered so that it is always immersed in the slurry to an appropriate depth. The pumping unit can also be moved around the barge to ensure that slurry is removed from all parts, particularly where the barge is compartmented or has ribs, e.g. stiffeners projecting upwardly from its bottom forming dead spaces in the slurry tank. The boom 20 may be mounted on a dockside or another vessel. A flexible pipe 40 takes the slurry to a desired location.

Claims (16)

  1. A device for pumping slurry, the device comprising:
    a screen adapted to pass only particles of less than a predetermined size and disposed generally horizontally with an inlet in its lower surface and an outlet in its upper surface;
    a positive displacement pump for pumping said slurry, said pump being disposed above said screen and having an inlet; and
    chamber connecting the outlet of said screen to the inlet of said pump.
  2. A device according to claim 1 wherein said pump is a progressing cavity pump.
  3. A device according to claim 1 or 2 wherein said chamber has upper and lower openings, said lower opening of said funnel-shaped chamber being larger than said upper opening thereof and communicating with said outlet of said screen and said upper opening communicating with said inlet of said pump.
  4. A device according to claim 3 wherein the cross-sectional area of said funnel-shaped chamber decreases monotonically from said lower opening to said upper opening.
  5. A device according to claim 1, 2, 3 or 4 wherein said screen is further adapted to break-up particles of greater than or equal to said predetermined size.
  6. A device according to claim 5 wherein said screen comprises a macerator having a macerating chamber with side walls and first and second parallel counter-rotatable shafts extending within said side walls, a plurality of alternating cutters and spacers mounted on each of said first and second shafts, the cutters of the first shaft being interleaved with those of the second shaft and at least one tooth being provided on each of said cutters.
  7. A device according to claim 6 wherein the axial thickness of said spacers is greater than the axial thickness of said cutters.
  8. A device according to claim 7 wherein the axial thickness of said spacers is greater than said axial thickness of said cutters by an amount in the range of from about 1 to about 50mm, preferably from 5 to 20mm.
  9. A device according to claims 7 or 8 further comprising a motor for driving one of said shafts and gears inter-connecting said shafts so that they counter-rotate.
  10. A device according to any one of the preceding claims further comprising at least one impeller disposed proximate said screen.
  11. A device for pumping slurry, the device comprising:
    a macerator having a macerating chamber having sidewalls and open upper and lower faces, two parallel, substantially horizontally disposed, shafts extending between opposite sidewalls of said macerating chamber, alternating cutter wheels and spacers disposed on said shafts, said cutter wheels having a greater diameter than said spacers and said cutter wheels on one of said shafts being interleaved with said cutter wheels on the other of said shafts, and means for driving said shafts to counter-rotate;
    a funnel chamber having upper and lower openings, said lower opening of said funnel chamber being larger than said upper opening thereof and communicating with said open upper face of said macerating chamber; and
    a pump of the progressing cavity type comprising a helical rotor of N starts and a stator having a helical bore therethrough complimentary to the rotor and having N ± 1 starts, said stator being generally vertically arranged, and said pump having an inlet end in communication with the upper opening of said funnel chamber;
    whereby in use said pump is operated to pump slurry out of said funnel chamber and thereby draw slurry in through said macerator, and said shafts of said macerator are counter-rotated so as to pass particles of less than a predetermined size and to break up particles of a greater than said predetermined size, said predetermined size being a size acceptable to said pump.
  12. A device according to any one of the preceding claims, said device being adapted to be operable when submerged in a slurry.
  13. A device according to any one of the preceding claims mounted on the end of a movable boom.
  14. A device according to any one of the claims 1 to 12 having attachment means to enable it to be suspended from a crane.
  15. A boom assembly comprising:
    a swingable boom; and
    a pumping unit mounted on the distal end of said boom and immersible in a slurry, said pumping unit comprising:
    a screen adapted to pass only particles of less than a predetermined size and disposed generally horizontally with an inlet in its lower surface and an outlet in its upper surface;
    a positive displacement pump for pumping said slurry, said pump being disposed above said screen and having an inlet; and
    chamber connecting the outlet of said screen to the inlet of said pump.
  16. A boom assembly according to claim 15 wherein said screen is a munching device for reducing oversize particles.
EP00302089A 1999-04-08 2000-03-15 Device for pumping slurry Withdrawn EP1043476A3 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB9908056 1999-04-08
GB9908056A GB2348674A (en) 1999-04-08 1999-04-08 Device for pumping slurry

Publications (2)

Publication Number Publication Date
EP1043476A2 true EP1043476A2 (en) 2000-10-11
EP1043476A3 EP1043476A3 (en) 2000-11-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP00302089A Withdrawn EP1043476A3 (en) 1999-04-08 2000-03-15 Device for pumping slurry

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EP (1) EP1043476A3 (en)
JP (1) JP2000303770A (en)
AU (1) AU2524500A (en)
CA (1) CA2304430A1 (en)
GB (1) GB2348674A (en)
NO (1) NO20001815L (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101708498B (en) * 2009-12-25 2011-09-14 天津开发区兰顿油田服务有限公司 Cleaning device of sediment on tank bottom
EP2376739A4 (en) * 2008-12-12 2017-10-25 Hydril USA Manufacturing LLC Subsea solids processing apparatuses and methods
CN111711317A (en) * 2020-08-14 2020-09-25 浙江研基科技有限公司 Chicken manure scattering equipment

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107520004A (en) * 2017-07-31 2017-12-29 晋江鑫迈医疗设备有限公司 A kind of feed-processing device and its processing method with uniform crushing function
US10287853B2 (en) * 2017-08-30 2019-05-14 Saudi Arabian Oil Company Well debris handling system
CN107755029B (en) * 2017-11-01 2020-01-17 安徽上造智能设备科技有限公司 Mushroom wood smashes sieving mechanism convenient to ejection of compact

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2596151A (en) * 1948-02-27 1952-05-13 Roy Bowling Pumping system
US3938744A (en) * 1974-09-05 1976-02-17 Allen Clifford H Positive displacement rotary pump and drive coupling therefor
US4182499A (en) * 1976-02-23 1980-01-08 Monogram Industries, Inc. Macerator pump
US4366063A (en) * 1981-06-17 1982-12-28 Romec Environmental Research & Development, Inc. Process and apparatus for recovering usable water and other materials from oil field mud/waste pits
US4635735A (en) * 1984-07-06 1987-01-13 Schlumberger Technology Corporation Method and apparatus for the continuous analysis of drilling mud
US4961689A (en) * 1987-07-27 1990-10-09 Avramidis Anestis S Positive displacement vacuum pumps
US5228506A (en) * 1991-12-04 1993-07-20 Pearce Stevan E Spill collection system for wellheads
US5303786A (en) * 1992-09-16 1994-04-19 Atlantic Richfield Company Earth drilling cuttings processing system
EP0713727A1 (en) * 1994-11-23 1996-05-29 Mono Pumps Limited Macerator
GB2318370A (en) * 1996-10-18 1998-04-22 Aea Technology Plc Disposal of waste materials on an oil rig
WO1998016717A1 (en) * 1996-10-15 1998-04-23 M-I L.L.C. Oil and gas well cuttings disposal system with continuous vacuum operation for sequentially filling disposal tanks
US5846440A (en) * 1995-12-12 1998-12-08 Angelle; Clinton J. Apparatus and method for handling waste

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3931936A (en) * 1974-06-05 1976-01-13 Continental Oil Company Apparatus for crushing solids in a liquid medium
GB2067905B (en) * 1980-01-22 1983-07-27 Mono Pumps Eng Ltd Method and apparatus for producing cement or plaster
EP0062129A3 (en) * 1981-03-27 1983-05-04 Mono Pumps Limited Method and apparatus for producing cement or plaster
SE459877B (en) * 1983-09-16 1989-08-14 Hans Baeckstroem DEVICE FOR THE TRANSPORT OF PAST PROTECTIVE DRUGS WITH THE PUMP PROTECTOR OF A ROTATING DEPLACEMENT TYPE
DE3833515C2 (en) * 1988-10-01 1996-07-11 Seepex Seeberger Gmbh & Co Machine unit for comminuting and conveying vegetable matter, meat and the like
US5431347A (en) * 1991-12-02 1995-07-11 Hitachi, Ltd. System and method for disposing waste
US5377707A (en) * 1993-11-01 1995-01-03 White Consolidated Industries, Inc. Dishwasher pump and filtration system

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2596151A (en) * 1948-02-27 1952-05-13 Roy Bowling Pumping system
US3938744A (en) * 1974-09-05 1976-02-17 Allen Clifford H Positive displacement rotary pump and drive coupling therefor
US4182499A (en) * 1976-02-23 1980-01-08 Monogram Industries, Inc. Macerator pump
US4366063A (en) * 1981-06-17 1982-12-28 Romec Environmental Research & Development, Inc. Process and apparatus for recovering usable water and other materials from oil field mud/waste pits
US4635735A (en) * 1984-07-06 1987-01-13 Schlumberger Technology Corporation Method and apparatus for the continuous analysis of drilling mud
US4961689A (en) * 1987-07-27 1990-10-09 Avramidis Anestis S Positive displacement vacuum pumps
US5228506A (en) * 1991-12-04 1993-07-20 Pearce Stevan E Spill collection system for wellheads
US5303786A (en) * 1992-09-16 1994-04-19 Atlantic Richfield Company Earth drilling cuttings processing system
EP0713727A1 (en) * 1994-11-23 1996-05-29 Mono Pumps Limited Macerator
US5846440A (en) * 1995-12-12 1998-12-08 Angelle; Clinton J. Apparatus and method for handling waste
WO1998016717A1 (en) * 1996-10-15 1998-04-23 M-I L.L.C. Oil and gas well cuttings disposal system with continuous vacuum operation for sequentially filling disposal tanks
GB2318370A (en) * 1996-10-18 1998-04-22 Aea Technology Plc Disposal of waste materials on an oil rig

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2376739A4 (en) * 2008-12-12 2017-10-25 Hydril USA Manufacturing LLC Subsea solids processing apparatuses and methods
CN101708498B (en) * 2009-12-25 2011-09-14 天津开发区兰顿油田服务有限公司 Cleaning device of sediment on tank bottom
CN111711317A (en) * 2020-08-14 2020-09-25 浙江研基科技有限公司 Chicken manure scattering equipment

Also Published As

Publication number Publication date
EP1043476A3 (en) 2000-11-15
GB2348674A (en) 2000-10-11
AU2524500A (en) 2000-10-12
CA2304430A1 (en) 2000-10-08
NO20001815D0 (en) 2000-04-07
NO20001815L (en) 2000-10-09
GB9908056D0 (en) 1999-06-02
JP2000303770A (en) 2000-10-31

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