WO1984001138A1 - Stripping system for a cargo tank - Google Patents

Stripping system for a cargo tank Download PDF

Info

Publication number
WO1984001138A1
WO1984001138A1 PCT/NO1983/000035 NO8300035W WO8401138A1 WO 1984001138 A1 WO1984001138 A1 WO 1984001138A1 NO 8300035 W NO8300035 W NO 8300035W WO 8401138 A1 WO8401138 A1 WO 8401138A1
Authority
WO
WIPO (PCT)
Prior art keywords
cargo
tank
auxiliary tank
discharge
pump
Prior art date
Application number
PCT/NO1983/000035
Other languages
French (fr)
Inventor
Henrik Pande-Rolfsen
Original Assignee
Thune Eureka As
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
Application filed by Thune Eureka As filed Critical Thune Eureka As
Publication of WO1984001138A1 publication Critical patent/WO1984001138A1/en

Links

Classifications

    • 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
    • F04D13/16—Pumping installations or systems with storage reservoirs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B27/00—Arrangement of ship-based loading or unloading equipment for cargo or passengers
    • B63B27/24—Arrangement of ship-based loading or unloading equipment for cargo or passengers of pipe-lines

Definitions

  • the invention relates to a stripping system for a cargo tank, comprising an auxiliary tank located at a level near the bottom of the cargo tank whose cargo is to be discharged, a vacuum source connected to the auxiliary tank to produce a partial vacuum in said tank relative to the cargo pressure, a valve permitting the cargo to flow from the cargo tank into the auxiliary tank at said partial vacuum, a discharge line for carrying the cargo away from the auxiliary tank, with an associated valve, and a pressure source connected to the auxiliary tank for increasing the pressure within the tank, thereby permitting the contents of the auxiliary tank to be forced out through the discharge line.
  • the invention has been developed in connection with the problem of discharging cargo from tanks on board a ship, which are emptied with the aid of suitable evacuation pump systems.
  • Various embodiments of systems to ensure evacua ⁇ tion of the last remaining part of the cargo are known in the prior art, see for example Norwegian Patents 106,490, 116,190, 116,790 and British Patent 1,058,244.
  • Norwegian Patent 116,190 in particular, it is known to provide an auxiliary tank within the storage tank itself, the auxiliary tank being connected to a vacuum source and a pressure source.
  • This auxiliary tank forms part of the evacuation pump system, and is utilized during the discharging process itself.
  • the object of the invention is to utilize the above strip ⁇ ping method in connection with submersible pumps that can be guided down into the cargo tank through a deck hatch, but wherein the stripping system is operative only when stripping of the tank contents is necessary.
  • a stripping system as defined above is constructed such that the auxiliary tank constitutes a part of a discharge pump that is submersible into the cargo tank via a deck hatch. With this arrangement, a compact system comprising both a discharge pump and a stripping system is obtained.
  • the stripping system and the discharge pump system are constructed as a single assembly, yet the strip ⁇ ping system is an independently operating unit.
  • a joint partial vacuum/pressure line extends from the auxiliary tank to a valve means above the deck level of the ship, the valve being connected to the vacuum source and the pressure source.
  • ⁇ 0 pressure sources occurs above deck, thereby permitting the same vacuum source to be utilized for one or more evacuation pumps, i.e., the pumps' respective stripping systems. Similarly, a common pressure source can be utilized for one or more stripping systems.
  • the pressure source is preferably an inert gas pressure source, but it may also be a compressed air system.
  • the two valves in the system i.e., the valve which opens to 20 permit inflow of cargo from the cargo tank into the auxiliary tank and the valve associated with the cargo discharge line, are preferably both non-return valves, opening in different respective directions.
  • the use of non-return valves simpli ⁇ fies control of the discharge system, since the valves do 25 not require remote control.
  • connection between the valve means and said vacuum/pressure line is 30 preferably a spool pipe.
  • the ship deck 1 on the drawing constitutes the upper boundary
  • IfUREA O PI of a cargo tank 2 having a bottom wall 3.
  • a well 4 is formed in the bottom wall 3 of the tank.
  • There is an opening 5 in the. deck 1 which is large enough to permit a discharge pump 6 to be guided down into the tank 2 for* unloading its cargo.
  • the pump has a pump housing 7 and a motor housing 8.
  • the motor housing is located above deck.
  • a cofferdam pipe 9 extends between the motor housing.8 and the pump housing 7 and the pump's drive shaft and riser pipe are arranged therein, in a manner known par se.
  • the pump suctions cargo from the cargo tank well 4 and forces it up through the riser pipe (not shown), to a location above deck, as indicated by the arrow L.
  • an auxiliary tank or compart ⁇ ment 1Q having two non-return valves 11 and 12 at the bottom thereof is disposed around the lower portion of the discharge pump 6.
  • the non-return valves 11 and 12 open in different respective directions of flow.
  • the non-return valve 11 is connected to a suction line 13 extending down to the bottom of the well 4.
  • the non-return valve 12 is connected to a line 14 extending above deck level, which functions as a discharge line during the stripping operation.
  • a line 15 extends from the top of the auxiliary compartment 10 to the deck, where it continues above deck as a line 16 leading to a valve means 17.
  • a vacuum source in this case a water ring pump 18, is connected to the valve means 17, and the valve 17 is also connected to a source of compressed air 21 and a source of pressurized inert gas 22 via lines 19 and 20, respectively.
  • the vacuum source and the pressure sources may be jointly used for several discharge pumps, i.e., the associated stripping systems of the pumps, and the connection between the line 15,16 and the valve means 17 is preferably effected by means of a spool pipe 23, to eliminate the risk of any
  • the novel stripping system operates in the following manner: When the discharge pump has suctioned off as much of the cargo as it can, the water ring pump 18 is started up. Its intake is via the valve means 17 that is connected via the spool pipe 23 to the line 16 and further to the line 15, and the water ring pump thus applies suction to the auxiliary compartment 1Q, thereby causing a partial vacuum in the compartment. Cargo is then suctioned into the auxiliary tank 10 through the suction line 13 and the non-return valve 11.
  • valve means 17 At the end of a predetermined interval, controlled by means of a timing mechanism (not illustrated) , the flow direction through the valve means 17 will be reversed, shutting off the suction from the water ring pump 18 and opening to permit the introduction of compressed inert gas or optionally compressed air.
  • the auxiliary tank 10 is thereby pressurized by the gas flowing into it through the line 16,15 and the cargo that has been suctioned into the auxiliary tank 10 is forced out through the non-return valve 12 and up to deck level through the line 14.
  • the valve means 17 At the next timing interval, the valve means 17 will open to permit suction from the water ring pump 18 and shut off the supply of pressure.
  • the pipe 16, as seen in the drawing, is made such that its highest point 16 r lies at least 10 meters above the bottom of the pump well 4, to prevent penetration of cargo into the water ring pump.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Ocean & Marine Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

In connection with a cargo discharge pump (6) that is submerged within a cargo tank (2), a stripping system that is utilized after most of the cargo has been pumped out of the tank by the discharge pump. An auxiliary tank (10) is arranged near the bottom of the discharge pump (6). Mounted at the bottom of the auxiliary tank are two non-return valves (11, 12), opening in opposite directions of flow. A suction line (13) is connected to one of the non-return valves (11) and extends down to the pump well (4) in the cargo tank (2). The other non-return valve (12) is connected to a line (14) for delivery of the cargo above deck level. A source of partial vacuum, for example a water ring pump (18), is mounted on deck for utilization by several discharge pumps (6). Mounted on the suction side of the water ring pump (18) is a valve means (17) which can be automatically controlled by a timing mechanism or in response to a partial vacuum in the suction line. The valve (17) is also connected to a pressurized gas system (21, 22). Alternating conditions of underpressure and overpressure within the auxiliary tank (19) cause any cargo remaining in the well (4) to be suctioned into the auxiliary tank, and to be forced to flow from the auxiliary tank up above deck through a discharge line (14). The components of the system are mounted on the discharge pump and the entire unit can be passed through the deck opening (5) for utilization/removal of the discharge pump.

Description

STRIPPING SYSTEM FOR A CARGO TANK
The invention relates to a stripping system for a cargo tank, comprising an auxiliary tank located at a level near the bottom of the cargo tank whose cargo is to be discharged, a vacuum source connected to the auxiliary tank to produce a partial vacuum in said tank relative to the cargo pressure, a valve permitting the cargo to flow from the cargo tank into the auxiliary tank at said partial vacuum, a discharge line for carrying the cargo away from the auxiliary tank, with an associated valve, and a pressure source connected to the auxiliary tank for increasing the pressure within the tank, thereby permitting the contents of the auxiliary tank to be forced out through the discharge line.
The invention has been developed in connection with the problem of discharging cargo from tanks on board a ship, which are emptied with the aid of suitable evacuation pump systems. Various embodiments of systems to ensure evacua¬ tion of the last remaining part of the cargo, called scraping or stripping systems, are known in the prior art, see for example Norwegian Patents 106,490, 116,190, 116,790 and British Patent 1,058,244. From Norwegian Patent 116,190 in particular, it is known to provide an auxiliary tank within the storage tank itself, the auxiliary tank being connected to a vacuum source and a pressure source. By operating a system of valves, the cargo is drawn up into the auxiliary tank and forced out through a discharge line. This auxiliary tank forms part of the evacuation pump system, and is utilized during the discharging process itself.
The object of the invention is to utilize the above strip¬ ping method in connection with submersible pumps that can be guided down into the cargo tank through a deck hatch, but wherein the stripping system is operative only when stripping of the tank contents is necessary. In accordance with the invention, therefore, a stripping system as defined above is constructed such that the auxiliary tank constitutes a part of a discharge pump that is submersible into the cargo tank via a deck hatch. With this arrangement, a compact system comprising both a discharge pump and a stripping system is obtained. The stripping system and the discharge pump system are constructed as a single assembly, yet the strip¬ ping system is an independently operating unit.
Preferably, a joint partial vacuum/pressure line extends from the auxiliary tank to a valve means above the deck level of the ship, the valve being connected to the vacuum source and the pressure source. The connection of the vacuum and
■0 pressure sources occurs above deck, thereby permitting the same vacuum source to be utilized for one or more evacuation pumps, i.e., the pumps' respective stripping systems. Similarly, a common pressure source can be utilized for one or more stripping systems.
15
The pressure source is preferably an inert gas pressure source, but it may also be a compressed air system.
The two valves in the system, i.e., the valve which opens to 20 permit inflow of cargo from the cargo tank into the auxiliary tank and the valve associated with the cargo discharge line, are preferably both non-return valves, opening in different respective directions. The use of non-return valves simpli¬ fies control of the discharge system, since the valves do 25 not require remote control.
To prevent admixture of the cargo from the different discharge pumps when utilizing a common vacuum source, the connection between the valve means and said vacuum/pressure line is 30 preferably a spool pipe.
The invention will be described in greater detail in the following with reference to the accompanying drawing, which is schematic and shows only those components that are 35 necessary for an understanding of the invention and its mode of operation.
The ship deck 1 on the drawing constitutes the upper boundary
IfUREA . O PI of a cargo tank 2 having a bottom wall 3. A well 4 is formed in the bottom wall 3 of the tank. There is an opening 5 in the. deck 1 which is large enough to permit a discharge pump 6 to be guided down into the tank 2 for* unloading its cargo. The pump has a pump housing 7 and a motor housing 8. The motor housing is located above deck. A cofferdam pipe 9 extends between the motor housing.8 and the pump housing 7 and the pump's drive shaft and riser pipe are arranged therein, in a manner known par se.
During unloading of the cargo, the pump suctions cargo from the cargo tank well 4 and forces it up through the riser pipe (not shown), to a location above deck, as indicated by the arrow L.
In the illustrated embodiment, an auxiliary tank or compart¬ ment 1Q having two non-return valves 11 and 12 at the bottom thereof is disposed around the lower portion of the discharge pump 6. The non-return valves 11 and 12 open in different respective directions of flow. The non-return valve 11 is connected to a suction line 13 extending down to the bottom of the well 4. The non-return valve 12 is connected to a line 14 extending above deck level, which functions as a discharge line during the stripping operation.
A line 15 extends from the top of the auxiliary compartment 10 to the deck, where it continues above deck as a line 16 leading to a valve means 17. A vacuum source, in this case a water ring pump 18, is connected to the valve means 17, and the valve 17 is also connected to a source of compressed air 21 and a source of pressurized inert gas 22 via lines 19 and 20, respectively.
The vacuum source and the pressure sources may be jointly used for several discharge pumps, i.e., the associated stripping systems of the pumps, and the connection between the line 15,16 and the valve means 17 is preferably effected by means of a spool pipe 23, to eliminate the risk of any
"BUREA OMP! admixture of the contents being unloaded by the different discharge pumps.
The novel stripping system operates in the following manner: When the discharge pump has suctioned off as much of the cargo as it can, the water ring pump 18 is started up. Its intake is via the valve means 17 that is connected via the spool pipe 23 to the line 16 and further to the line 15, and the water ring pump thus applies suction to the auxiliary compartment 1Q, thereby causing a partial vacuum in the compartment. Cargo is then suctioned into the auxiliary tank 10 through the suction line 13 and the non-return valve 11. At the end of a predetermined interval, controlled by means of a timing mechanism (not illustrated) , the flow direction through the valve means 17 will be reversed, shutting off the suction from the water ring pump 18 and opening to permit the introduction of compressed inert gas or optionally compressed air. The auxiliary tank 10 is thereby pressurized by the gas flowing into it through the line 16,15 and the cargo that has been suctioned into the auxiliary tank 10 is forced out through the non-return valve 12 and up to deck level through the line 14. At the next timing interval, the valve means 17 will open to permit suction from the water ring pump 18 and shut off the supply of pressure.
All components found within the cargo tank 2 during use of the discharge pump are dimensioned to permit the discharge pump 6. to be guided down into and drawn up from the tank through the deck opening 5.
The pipe 16, as seen in the drawing, is made such that its highest point 16r lies at least 10 meters above the bottom of the pump well 4, to prevent penetration of cargo into the water ring pump.

Claims

Patent Claims.
1. - A stripping system for a cargo tank, comprising an auxiliary tank situated at a level near the bottom of the cargo tank whose cargo is to be discharged, a vacuum source connected to the auxiliary tank for causing a partial vacuum i*n the auxiliary tank relative to the pressure of the cargo, a valve that opens to permit inflow of cargo into the auxiliary tank from the cargo tank at said partial vacuum, a discharge line for carrying off the cargo from the auxiliary tank, with an associated valve, and a pressure source connected to the auxiliary tank for pressurizing said tank, and thereby causing the contents of the auxiliary tank to be forced out through the discharge line, characterized in that the auxiliary tank (10). is an integral part of a discharge pump (6). that is submersible into the cargo tank (2) via a deck hatch (5)..
2. A stripping system according to claim 1, character¬ ized in that a joint partial vacuum/pressure line (15,16) extends from the auxiliary tank (10) to a valve means (17) above deck level, said valve means (17) being connected to the vacuum source (18) and pressure source (21,22) .
3. A stripping system according to claims 1 or 2, characterized by a common vacuum source (18) serving several discharge pumps (6) .
4. A stripping system according to claims 1, 2 or 3, characterized by a common pressure source (21,22) serving several discharge pumps (6) .
5. A stripping system according to one of the claims 1 - 4, characterized in that said two valves (11,12). are non-return valves opening for opposite directions of flow.
6. A stripping system according to one of the claims . 2 - 5, characterized in that the connection between the valve means (17). and said vacuum/pressure line (15,16) is effected via a spool pipe (23)..
Abstract^
In-connection with a cargo discharge pump (6) that is submerged within a cargo tank (2) , a stripping system is described that is utilized after most of the cargo has been pumped out of the tank by the discharge pump. An auxiliary tank (10). is arranged near the bottom of the discharge pump (6).. Mounted at the bottom of the auxiliary tank are two non-return valves (11,12)., opening in opposite directions of flow. A suction line (13) is connected to one of the non-return valves (11) and extends down to the pump well (4) in the cargo tank (2) .
The other non-return valve (12) is connected to a line (14) for delivery of the cargo above deck level. A source of partial vacuum, for example a water ring pump (18) , is mounted on deck for utilization by several discharge pumps (6).. Mounted on the suction side of the water ring pump (18) is a valve means (17) which can be automatically controlled by a timing mechanism or in response to a partial vacuum in the suction line. The valve (17) is also connected to a pressurized gas system (21,22).. Alternating conditions of underpressure and overpressure within the auxiliary tank (19) cause any cargo remaining in the well (4) to be suctioned into the auxiliary tank, and to be forced to flow from the auxiliary tank up above deck through a discharge line (14) .
The components of the system.are mounted on the discharge pump and the entire unit can be passed through the deck opening (5) for utilization/removal of the discharge pump.
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OMPΪ o$ , wipo
PCT/NO1983/000035 1982-09-21 1983-09-21 Stripping system for a cargo tank WO1984001138A1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NO823184A NO160766C (en) 1982-09-21 1982-09-21 STRIP SYSTEM FOR A LOAD TANK.

Publications (1)

Publication Number Publication Date
WO1984001138A1 true WO1984001138A1 (en) 1984-03-29

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1983/000035 WO1984001138A1 (en) 1982-09-21 1983-09-21 Stripping system for a cargo tank

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WO (1) WO1984001138A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0722883A1 (en) * 1995-01-18 1996-07-24 Societa' Esercizio Cantieri S.P.A. Method and apparatus for draining a liquid from a tank
EP0757183A1 (en) * 1995-08-02 1997-02-05 Mario Pierotti Machine for lifting liquids
WO1997006050A1 (en) * 1995-08-10 1997-02-20 Frank Mohn Fusa A/S Cargo discharging pump
NL1006430C2 (en) * 1996-06-28 1999-06-08 Bornemann J H Gmbh & Co Method for emptying a tank and a pump for pumping it out.
EP0839708A3 (en) * 1992-01-28 1999-12-01 Frank Mohn Fusa A/S Process and arrangement for draining a liquid residue from the bottom of a tank
NO337187B1 (en) * 2015-02-03 2016-02-08 Vitallic As Device and Method for Emptying Cargo from a Tank

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO179317C (en) * 1994-06-13 1996-09-18 Preben Rasmussen Apparatus and method for continuous emptying of liquid-filled tank

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO147869B (en) * 1981-02-02 1983-03-21 Patents & Dev As PROCEDURE AND SYSTEM FOR EMPTYING A LIQUID MEDIUM FROM A CONTAINER, FOR EXAMPLE A SHIP TANK

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NO147869B (en) * 1981-02-02 1983-03-21 Patents & Dev As PROCEDURE AND SYSTEM FOR EMPTYING A LIQUID MEDIUM FROM A CONTAINER, FOR EXAMPLE A SHIP TANK

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0839708A3 (en) * 1992-01-28 1999-12-01 Frank Mohn Fusa A/S Process and arrangement for draining a liquid residue from the bottom of a tank
EP0722883A1 (en) * 1995-01-18 1996-07-24 Societa' Esercizio Cantieri S.P.A. Method and apparatus for draining a liquid from a tank
EP0757183A1 (en) * 1995-08-02 1997-02-05 Mario Pierotti Machine for lifting liquids
WO1997006050A1 (en) * 1995-08-10 1997-02-20 Frank Mohn Fusa A/S Cargo discharging pump
NL1006430C2 (en) * 1996-06-28 1999-06-08 Bornemann J H Gmbh & Co Method for emptying a tank and a pump for pumping it out.
NO337187B1 (en) * 2015-02-03 2016-02-08 Vitallic As Device and Method for Emptying Cargo from a Tank
NO20150152A1 (en) * 2015-02-03 2016-02-08 Vitallic As Device and Method for Emptying Cargo from a Tank

Also Published As

Publication number Publication date
NO823184L (en) 1984-03-22
NO160766C (en) 1991-12-24
NO160766B (en) 1989-02-20

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