Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
  • F04C11/00—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations
  • F04C11/005—Combinations of two or more machines or pumps, each being of rotary-piston or oscillating-piston type; Pumping installations of dissimilar working principle
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B23/00—Pumping installations or systems
  • F04B23/04—Combinations of two or more pumps
  • F04B23/08—Combinations of two or more pumps the pumps being of different types
  • F04B23/10—Combinations of two or more pumps the pumps being of different types at least one pump being of the reciprocating positive-displacement type
  • F04B23/103—Combinations of two or more pumps the pumps being of different types at least one pump being of the reciprocating positive-displacement type being a radial piston pump
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B23/00—Pumping installations or systems
  • F04B23/04—Combinations of two or more pumps
  • F04B23/08—Combinations of two or more pumps the pumps being of different types
  • F04B23/14—Combinations of two or more pumps the pumps being of different types at least one pump being of the non-positive-displacement type
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D13/00—Pumping installations or systems
  • F04D13/12—Combinations of two or more pumps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D31/00—Pumping liquids and elastic fluids at the same time

Definitions

• a pumping arrangement for pumping a liquid product from a tank or container
• the present invention relates to a pumping arrangement for pumping a liquid product from a tank or container.
• FR 548,486 discloses a pumping arrangement comprising a centrifugal pump and a piston pump, which pumps are driven by a common driving shaft.
• the piston pump is active during the first part of a pumping operation for sucking liquid to a level above the centrifugal pump. Thereafter, the piston pump is inactivated, and the centrifugal pump becomes active.
• the driving shaft constantly drives both of the pumps.
• WO 97 27403 discloses an unloading pump arrangement positioned in a well of a cargo tank.
• This pump arrangement comprises a main pump, which is a centrifugal pump, and an auxiliary pump in the form of a conical sleeve.
• the sleeve-like auxiliary pump extends downwardly from and is driven by the impeller of the main pump. Also in this case the auxiliary pump is driven also when the main pump is operating and vice versa.
• the present invention provides a pumping arrangement, which is able to pump liquid from a container or tank and to empty it almost completely, and which may be made and/or operated more simple and economical than the known pumping arrangements discussed above.
• the present invention provides a pumping arrangement for pumping a liquid product from a tank or container and comprising a rotary, high capacity main pump to be submerged in the product, a rotary driving motor for driving the rotary main pump via a driving shaft, an auxiliary positive pump for pumping a residual amount of said liquid product from the tank or container, and means for selectively drivingly connecting the auxiliary pump to the driving shaft of the main pump.
• the auxiliary pump may be connected to the driving shaft only when the auxiliary pump is needed. This is possible because operation of the high capacity main pump and of the auxiliary pump is not required at the same time.
• the main pump may be any high capacity rotary pump. In the preferred embodiment, however, the main pump is a centrifugal pump, but may, for example, also be a gear pump.
• the auxiliary pump may be any pump, which able to efficiently pump a mixture of liquid and gas. However, preferably the auxiliary pump is a piston pump, but may, alternatively, be any other positive pump.
• the common driving motor may be a pneumatic or hydraulic motor, which may be submerged in or positioned above the upper level of the liquid product being pumped.
• the driving motor is an electric motor.
• Such motor may be submerged, but is preferably arranged above the liquid level in the tank or container.
• the auxiliary pump need not be submerged in the liquid product, but may be positioned above the upper liquid level provided that the height, in which the auxiliary pump is positioned above the bottom of the tank or container or above the inlet end of the suction tube of the pump, is sufficiently small to allow the pump to efficiently pump a liquid product from the bottom of the tank. It is preferred, however, that the auxiliary pump is adapted to be submerged in the liquid product to be pumped.
• the means for interconnecting the auxiliary pump to the driving shaft of the main pump may be of any kind, such as mechanical and/or electrical.
• the means for bringing the driving shaft into and out of driving engagement with the pump may be operated mechanically or electrically by an operator, or they may be operated automatically, for example by a level detector generating an activating signal when the liquid level has reached a predetermined low value.
• the main pump may be disengaged from the driving motor when the auxiliary pump is dnvingly interconnected with the driving shaft Alternatively, the main pump and the auxiliary pump may be operating at the same time
• the means for interconnecting the auxiliary pump to the driving shaft of the main pump may be activated by reversing the direction of rotation of the driving shaft In this case the impeller of the main pump will rotate, but not be active
• the pumping arrangement may comprise a device for driving the auxiliary pump
• This device may be adapted to automatically become disengaged from the driving shaft when this shaft is being rotated in one direction to drive the main pump, and to become engaged with the driving shaft when the direction of rotation is reversed
• the auxiliary pump is activated while the main pump is idling
• the interconnecting means may comprise an annular member arranged loosely around the driving shaft and means for selectively locking the annular member to the driving shaft
• the locking means may be activated manually or automatically as mentioned above
• the outer peripheral surface of the annular member may define an eccentric or a cam surface for reciprocatingly driving a piston of the auxiliary pump
• the automatic activation of the locking means is obtained by means of a ratchet device
• the locking means may be activated automatically by reversing the rotational direction of the driving motor or the driving shaft
• the pumping arrangement may comprise ratchet teeth formed on an annular end surface part of the annular member and at least one pawl member arranged axially opposite to the ratchet teeth and being connected to the driving shaft so as to rotate together therewith
• the pawl members may be of any known type
• at least one pawl member may be a pin-like member extending from and movably arranged in an axial bore, the pin-like member being biased into engagement with the ratchet teeth
• the auxiliary pump may be of any conventional type, whether single or double acting
• each piston of the auxiliary piston pump has a peripheral outer seal dividing the cylinder space into smaller and a larger volume pumping chambers, the larger volume pumping chamber having inlet and outlet valves associated therewith, and the outlet valve communicating permanently with the smaller volume pumping chamber, whereby the smaller volume pumping chamber may function as a buffer chamber.
• the discharge flow from a pump of this type is less pulsating than when a conventional piston pump is used.
• Fig. 1 is a side view of a conventional pumping arrangement for discharging liquid products from tanks in ships or from similar large containers,
• Fig. 2 is a sectional view of the lower part of an embodiment of the pumping arrangement according to the invention.
• Fig. 3 is a sectional view in an enlarged scale of the piston pump shown in Fig. 2.
• Fig 1 shows a pumping system or pumping arrangement of the known type used as a cargo pump for pumping a liquid product 10, such as petroleum products or liquid chemicals from a tank or container 11 in a tanker, a barge or another vessel.
• the pumping system comprises a centrifugal pump 12 submerged in the liquid 10.
• the pump 12 has an inlet opening 13, which is positioned in a depression 14 formed in the bottom of the tank or container 11.
• a discharge or outlet tube 15 extends upwardly from the centrifugal pump to a flanged end 16 outside the tank 11.
• the centrifugal pump 12 is driven by an electric motor 17, which is positioned outside the tank 11 , and which is drivingly connected to the impeller of the pump 12 by means of a driving shaft extending trough a vertically arranged cylindrical, oil-filled housing 18.
• purging conduits 19, which extend from a sealed space within the oil-filled housing 18 and out from the tank 11 , renders it possible to check whether the sealing of the oil- filled housing 18 is tight.
• the whole pumping system forms a unit, which is mounted on a cover or lid 20.
• the cover 20 is detachably connected to a collar 21 defining a well opening in the top wall of the tank 11. This means that the whole pumping unit may be removed from the tank 11 by releasing the cover 20 from the collar 21.
• the centrifugal pump 12 is not able to empty the tank 11 completely. Therefore, in order to comply with international regulations regarding the amount left in the cargo tank when the tank is flushed or cleaned the conventional pumping system described may further be provided with a stripping facility requiring supply of compressed air or nitrogen. As another possibility, the system may include a separate stripping pump, which may be a double- acting, submerged piston pump (not shown). The outlet of the stripping pump may then be connected to an outlet or stripping conduit shown in Fig. 1.
• Figs 2 and 3 illustrate how the pumping system shown in Fig. 1 can be modified so as to 5 form an embodiment of the pumping arrangement according to the invention.
• Fig. 2 shows the centrifugal pump 12 having an impeller 23, which is fastened to the lower end of the driving shaft 24, the other end of the shaft being connected to the electric motor 17.
• the shaft 24 is mounted rotatably within the housing 18 by means of ball bearings 25
• the inner space of the cylindrical housing 18 is oil- filled, and an air-filled space 27 is defined around the driving shaft 24 and between an upper sealed oil-filled space and a lower sealed space.
• the space 27 is connected to the purging conduits 19. A possible leakage may be detected by blowing compressed air
• the pumping arrangement shown in Figs. 2 and 3 comprises a piston pump 29 having a frame 30 which is connected to the outer side of the housing 18 by bolts or similar releasable fastening means.
• the frame 30 defines a pump cylinder 31 in which a piston
• the 20 32 may reciprocate.
• the piston 32 is driven by an annular driving member 33, which is positioned around a section of the driving shaft 24 so as to be rotatable in relation thereto.
• the outer peripheral surface of the driving member 33 is cylindrical. However, the axis of the peripheral surface is offset in relation to the axis of the driving shaft 24 so as to define an eccentric.
• the outer peripheral surface of the driving member 33 co-operates with a
• this bore comprises an air-filled space 38, which may be connected with purging
• conduits 39 performing a function similar to that of the purging conduits 19 and the space 27 mentioned above.
• An annular connecting member 40 is arranged around the driving shaft 24 and is connected thereto by means of a key 41.
• the connecting member has a number of axial 35 bores opening into the lower end surface of the connecting member 40, and each of these bores receives a connecting pin 42 with a sliding fit
• the pins 42 are biased by gravity and possibly also by spring means positioned within the pin receiving bores towards an extended position in which the outer free ends of the pins are engaging with the adjacent upper end surface of the annular driving member 33
• This end surface has an annular arrangement of ratchet teeth 43 formed thereon for co-operation with the connecting pins 42
• the ratchet teeth are shaped such that the driving shaft 24 may rotate freely in relation to the driving member 33 in the usual rotational direction during operation of the centrifugal pump 12 while the driving shaft 24 is dnvingly interconnected with the annular driving member 33 by the ratchet device 42, 43 when the shaft is rotated in the opposite direction
• the pins 42 could be replaced by other types of pawl
• the piston pump 29 has a suction tube or an inlet tube 44 having its free end positioned in the depression 14 and an outlet tube 45
• the pump 29 is a kind of double-acting pump having two cylinder chambers, namely a pumping chamber 46 and an auxiliary chamber or buffer chamber 47
• the pumping chamber 46 is connected to the inlet tube 44 via a suction valve or inlet valve 48 and to the outlet tube 45 via a pressure valve or outlet valve 48
• the auxiliary chamber or buffer chamber 47 is permanently connected to the outlet tube 45 via a passage 50 Because the auxiliary chamber 47 is increasing in volume when the volume of the pumping chamber is decreasing and vice versa the chamber 47 may serve as a buffer chamber reducing the pressure pulse height of the pumped fluid flow

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)
• Reciprocating Pumps (AREA)
• Jet Pumps And Other Pumps (AREA)
• Details Of Reciprocating Pumps (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8097710

Family Applications (1)

Country Status (7)

Cited By (3)

Families Citing this family (1)

Citations (5)

• 2000
  • 2000-06-06 DE DE60004533T patent/DE60004533D1/de not_active Expired - Lifetime
  • 2000-06-06 WO PCT/DK2000/000302 patent/WO2000075518A1/en not_active Ceased
  • 2000-06-06 JP JP2001501768A patent/JP4237438B2/ja not_active Expired - Lifetime
  • 2000-06-06 DK DK00938577T patent/DK1200738T3/da active
  • 2000-06-06 EP EP00938577A patent/EP1200738B1/en not_active Expired - Lifetime
  • 2000-06-06 AT AT00938577T patent/ATE247229T1/de not_active IP Right Cessation
• 2001
  • 2001-12-06 NO NO20015978A patent/NO332074B1/no not_active IP Right Cessation

Patent Citations (5)

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