WO2009022913A1 - Method and device for treatment of ballast water - Google Patents

Method and device for treatment of ballast water Download PDF

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Publication number
WO2009022913A1
WO2009022913A1 PCT/NO2008/000290 NO2008000290W WO2009022913A1 WO 2009022913 A1 WO2009022913 A1 WO 2009022913A1 NO 2008000290 W NO2008000290 W NO 2008000290W WO 2009022913 A1 WO2009022913 A1 WO 2009022913A1
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WO
WIPO (PCT)
Prior art keywords
ballast water
down pipe
ozone
ballast
treatment
Prior art date
Application number
PCT/NO2008/000290
Other languages
French (fr)
Inventor
Per Lothe
Original Assignee
Knutsen Oas Shipping 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 Knutsen Oas Shipping As filed Critical Knutsen Oas Shipping As
Publication of WO2009022913A1 publication Critical patent/WO2009022913A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/78—Treatment of water, waste water, or sewage by oxidation with ozone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B13/00—Conduits for emptying or ballasting; Self-bailing equipment; Scuppers
    • B63B13/02—Ports for passing water through vessels' sides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63J—AUXILIARIES ON VESSELS
    • B63J4/00—Arrangements of installations for treating ballast water, waste water, sewage, sludge, or refuse, or for preventing environmental pollution not otherwise provided for
    • B63J4/002—Arrangements of installations for treating ballast water, waste water, sewage, sludge, or refuse, or for preventing environmental pollution not otherwise provided for for treating ballast water
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
    • C02F2103/008—Originating from marine vessels, ships and boats, e.g. bilge water or ballast water
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00—General aspects of water treatment
    • C02F2301/06—Pressure conditions
    • C02F2301/063—Underpressure, vacuum

Definitions

  • This invention relates to a method for treatment of ballast water. More particularly it relates to a method of treating ballast water, in which the ballast water is conveyed into a ballast tank via a down pipe, and in which an underpressure created at the upper portion of the down pipe induces the formation of gas bubbles in the ballast water, and in which ozone is added to the ballast water before or as the ballast water enters the down pipe.
  • the invention also includes a de- vice for practising the invention.
  • ballast When a ship is sailing, there must, for ship-technical reasons, be some cargo in the ship. As is well known, not- income-earning cargo is called ballast.
  • Sea water is widely used as ballast because of the relatively easy loading and unloading of the sea water. A great many species of organisms are carried in the ballast water from the place where it is loaded to the place of unloading.
  • ballast water A great part of the living organisms die during the transport and more die when they are released at the place of unload- ing. However, in favourable conditions a procreative stock may survive.
  • a supply of foreign organisms to a new place has been known to have catastrophic consequences to, among other things, the fisheries in entire sea areas.
  • New directives for the treatment of ballast water with a view to rendering organisms harmless are being drawn up in international bodies. The directives emphasize that treatment of the ballast water must be safe, it must be environmentally acceptable, it must be reasonable in use and it must work.
  • ballast water It is known to expose the ballast water to a relatively brief underpressure to destroy larger living organisms, for example crawfish.
  • an underpressure has little or no effect on, for example, bacteria or viruses.
  • ballast water is therefore often treated with chlorine.
  • chlorine together with the bromide occurring naturally in sea water may have adverse effects on the environment at the ballast water discharging site .
  • ozone is pumped into the ballast tank through one or more distributing pipes.
  • this method is conditional on a relative large amount of ozone having to be used to obtain a satisfactory effect.
  • Lar- ger organisms are less sensitive to ozone in the relatively low concentrations that are relevant here.
  • the invention has for its object to remedy or reduce at least one of the drawbacks of the prior art .
  • a method in accordance with the invention for treating ballast water in which the ballast water is carried into a ballast tank via a down pipe, and in which an underpressure cre- ated at the upper portion induces the formation of gas bubbles in the ballast water, is characterized by the addition of ozone to the ballast water before or as the ballast water enters the down pipe .
  • Ozone is preferably added at an upper portion of a riser up- stream of the down pipe .
  • the Froude number F which is non-dimensional, is defined as a ratio between the inertia force and the gravity force acting on a fluid:
  • V fluid velocity in metres per second
  • g the earth gravitation in metres per second 2
  • h m the hydraulic mean depth
  • the diameter of the loading column is dependent, in the main, on the velocity of the entering fluid.
  • the best mixing of ozone in the ballast water is achieved by a Froude number which is greater than 0.35.
  • a down pipe device for ballast water flowing to a ballast tank in which underpressure in the down pipe induces the formation of gas bubbles in the ballast water, and in which there is arranged an upstream inlet for ozone, is formed with a sufficient height above the deck of a vessel, typically in the order of 10 metres, to achieve a sufficient boiling action in the sea water at the upper portion of the down pipe.
  • Ozone present in, or being introduced into, the ballast water gets mixed into the ballast water very well in the down pipe while the ballast water is in turbulent flow, especially be- cause of the boiling action going on. Most of the ozone is dissolved in the ballast water during the flow of the ballast water down the down pipe, and therefore practically no free ozone is emitted to the atmosphere.
  • the method and the device according to the invention provide a relatively simple and cost-effective solution for treating ballast water. Larger organisms are rendered harmless by underpressure in the down pipe, whereas smaller organisms and viruses are killed by means of ozone.
  • Figure 1 shows in section a principle drawing of a vessel which is provided with a device in accordance with the invention; and Figure 2 shows an alternative embodiment of the device of figure 1.
  • the reference numeral 1 indicates a down pipe located on board a vessel 2. Ballast water is pumped by means of a ballast pump 4 from the sea 6 at the vessel 2 and via a riser 8 up to the upper portion 10 of the down pipe 1.
  • the riser 8 may be provided with one or more flow-controlling devices, not shown. From the upper portion 10 of the riser 1 the ballast water flows down to a ballast tank 12 in the ves- sel 2.
  • Ozone is generated, in a manner known per se, by means of an ozone generator 14. Ozone is carried via an ozone pipe 16 from the ozone generator 14 into the ballast water upstream of the down pipe 1.
  • ballast water when the ballast water is pumped up via the riser 9 by means of the ballast pump 4 in an amount maintaining the Froude number in the down pipe at a value greater than 0.35, ozone is added to the ballast water upstream of the down pipe 1.
  • Ozone flows down together with the ballast water via the down pipe 1 in which the ozone substantially dissolves in the ballast water.
  • the down pipe 1 discharges into a separator 18. Separated material is pumped by means of a sludge pump 20 via a sludge pipe 22 into the sea 6.
  • Treated ballast water flows from the separator 18 into the ballast tank 12 via a connecting pipe 24.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Organic Chemistry (AREA)
  • Public Health (AREA)
  • Toxicology (AREA)
  • General Health & Medical Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Physical Water Treatments (AREA)

Abstract

A method of treating ballast water, in which the ballast water is conveyed into a ballast tank (12) via a down pipe (1), and in which an underpressure created at the upper portion (10) of the down pipe (1) induces the formation of gas bubbles in the ballast water, and in which ozone is added to the ballast water before or as the ballast water enters the down pipe (1).

Description

METHOD AND DEVICE FOR TREATMENT OF BALLAST WATER
This invention relates to a method for treatment of ballast water. More particularly it relates to a method of treating ballast water, in which the ballast water is conveyed into a ballast tank via a down pipe, and in which an underpressure created at the upper portion of the down pipe induces the formation of gas bubbles in the ballast water, and in which ozone is added to the ballast water before or as the ballast water enters the down pipe. The invention also includes a de- vice for practising the invention.
When a ship is sailing, there must, for ship-technical reasons, be some cargo in the ship. As is well known, not- income-earning cargo is called ballast.
Sea water is widely used as ballast because of the relatively easy loading and unloading of the sea water. A great many species of organisms are carried in the ballast water from the place where it is loaded to the place of unloading.
A great part of the living organisms die during the transport and more die when they are released at the place of unload- ing. However, in favourable conditions a procreative stock may survive. A supply of foreign organisms to a new place has been known to have catastrophic consequences to, among other things, the fisheries in entire sea areas. New directives for the treatment of ballast water with a view to rendering organisms harmless are being drawn up in international bodies. The directives emphasize that treatment of the ballast water must be safe, it must be environmentally acceptable, it must be reasonable in use and it must work.
It is known to expose the ballast water to a relatively brief underpressure to destroy larger living organisms, for example crawfish. However, an underpressure has little or no effect on, for example, bacteria or viruses.
According to the prior art, ballast water is therefore often treated with chlorine. However, chlorine together with the bromide occurring naturally in sea water may have adverse effects on the environment at the ballast water discharging site .
It is also known to use ozone for the treatment of ballast water. According to the prior art, ozone is pumped into the ballast tank through one or more distributing pipes. However this method is conditional on a relative large amount of ozone having to be used to obtain a satisfactory effect. Lar- ger organisms are less sensitive to ozone in the relatively low concentrations that are relevant here.
The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art .
The object is achieved in accordance with the invention through the features which are specified in the description below and in the claims that follow.
A method in accordance with the invention for treating ballast water, in which the ballast water is carried into a ballast tank via a down pipe, and in which an underpressure cre- ated at the upper portion induces the formation of gas bubbles in the ballast water, is characterized by the addition of ozone to the ballast water before or as the ballast water enters the down pipe .
Ozone is preferably added at an upper portion of a riser up- stream of the down pipe .
It is advantageous for the down pipe to be given a sufficient drop for the water to boil at the upper portion of the down pipe.
From the open-channel hydraulics the so-called Froude number is known. The Froude number F, which is non-dimensional, is defined as a ratio between the inertia force and the gravity force acting on a fluid:
F = kK in which V = fluid velocity in metres per second, g = the earth gravitation in metres per second2 and hm = the hydraulic mean depth.
By replacing the hydraulic depth hm in the formula with the diameter D of the down pipe, an expression is found which has turned out to be practical when choosing the appropriate down pipe diameter.
The development work which has been carried out has shown that the mixing of ozone in ballast water is satisfactory when the value of the expression
Figure imgf000004_0001
is greater than 0.32. Thus, the diameter of the loading column is dependent, in the main, on the velocity of the entering fluid.
The best mixing of ozone in the ballast water is achieved by a Froude number which is greater than 0.35.
A down pipe device for ballast water flowing to a ballast tank, in which underpressure in the down pipe induces the formation of gas bubbles in the ballast water, and in which there is arranged an upstream inlet for ozone, is formed with a sufficient height above the deck of a vessel, typically in the order of 10 metres, to achieve a sufficient boiling action in the sea water at the upper portion of the down pipe.
Ozone present in, or being introduced into, the ballast water gets mixed into the ballast water very well in the down pipe while the ballast water is in turbulent flow, especially be- cause of the boiling action going on. Most of the ozone is dissolved in the ballast water during the flow of the ballast water down the down pipe, and therefore practically no free ozone is emitted to the atmosphere.
The method and the device according to the invention provide a relatively simple and cost-effective solution for treating ballast water. Larger organisms are rendered harmless by underpressure in the down pipe, whereas smaller organisms and viruses are killed by means of ozone.
In what follows is described an example of a preferred method and embodiment which are visualized in the accompanying drawings, in which:
Figure 1 shows in section a principle drawing of a vessel which is provided with a device in accordance with the invention; and Figure 2 shows an alternative embodiment of the device of figure 1.
In the drawings the reference numeral 1 indicates a down pipe located on board a vessel 2. Ballast water is pumped by means of a ballast pump 4 from the sea 6 at the vessel 2 and via a riser 8 up to the upper portion 10 of the down pipe 1.
The riser 8 may be provided with one or more flow-controlling devices, not shown. From the upper portion 10 of the riser 1 the ballast water flows down to a ballast tank 12 in the ves- sel 2.
Ozone is generated, in a manner known per se, by means of an ozone generator 14. Ozone is carried via an ozone pipe 16 from the ozone generator 14 into the ballast water upstream of the down pipe 1.
In the treatment of ballast water, when the ballast water is pumped up via the riser 9 by means of the ballast pump 4 in an amount maintaining the Froude number in the down pipe at a value greater than 0.35, ozone is added to the ballast water upstream of the down pipe 1.
Ozone flows down together with the ballast water via the down pipe 1 in which the ozone substantially dissolves in the ballast water.
In an alternative embodiment, see figure 2, the down pipe 1 discharges into a separator 18. Separated material is pumped by means of a sludge pump 20 via a sludge pipe 22 into the sea 6.
Treated ballast water flows from the separator 18 into the ballast tank 12 via a connecting pipe 24.

Claims

C l a i m s
1. A method of treating ballast water, in which the ballast water is conveyed into a ballast tank (12) via a down pipe (1) , and in which an underpressure created 5 at the upper portion (10) of the down pipe (1) induces the formation of gas bubbles in the ballast water, c h a r a c t e r i z e d i n that ozone is added to the ballast water before or as the ballast water enters the downpipe . o
2. The method in accordance with claim 1, c h a r a c t e r i z e d i n that the down pipe (1) is formed with a Froude number which is greater than 0.32.
3. The method in accordance with claim 1, c h a r a c t e r i z e d i n that the down pipe (1) is formeds with a Froude number which is greater than 0.35.
4. A device for a down pipe (1) for ballast water to a ballast tank (12) , in which underpressure in the down pipe (1) induces the formation of gas bubbles in the ballast water, c h a r a c t e r i z e d i n that ano inlet for ozone, which is located upstream of the down pipe (1) , communicates with the down pipe (1) .
5. The device in accordance with claim 4, c h a r a c t e r i z e d i n that the down pipe (1) discharges into a separator (18) which communicates with the bal-5 last tank (12) .
PCT/NO2008/000290 2007-08-13 2008-08-12 Method and device for treatment of ballast water WO2009022913A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO20074154A NO20074154L (en) 2007-08-13 2007-08-13 Method and apparatus for treating ballast water
NO20074154 2007-08-13

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010149638A1 (en) 2009-06-23 2010-12-29 Desmi Ocean Guard A/S Ballast water treatment
WO2011105911A1 (en) 2010-02-24 2011-09-01 Knutsen Ballastvann As Method and device for treatment of water
NO20200388A1 (en) * 2019-04-03 2020-10-05 Knutsen Tech As An arrangement and a method for reducing a content of dissolved gas from a gas-containing liquid

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4597877A (en) * 1984-02-23 1986-07-01 Bbc Brown, Boveri & Company, Ltd. Process and equipment for water treatment
US6001247A (en) * 1996-05-01 1999-12-14 Schulz; Christopher R. Removable, in-line diffuser apparatus for ozone disinfection of water
WO2005009907A1 (en) * 2003-07-24 2005-02-03 Knutsen Oas Shipping As Method and device for removal of gases from water
WO2006137121A1 (en) * 2005-06-20 2006-12-28 Ohr Laboratory Corporation Ballast water treating apparatus
WO2007049139A2 (en) * 2005-10-28 2007-05-03 Resource Ballast Technologies (Proprietary) Limited Method and apparatus for water treatment to eliminate aquatic organisms by an abrupt pressure reduction

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4597877A (en) * 1984-02-23 1986-07-01 Bbc Brown, Boveri & Company, Ltd. Process and equipment for water treatment
US6001247A (en) * 1996-05-01 1999-12-14 Schulz; Christopher R. Removable, in-line diffuser apparatus for ozone disinfection of water
WO2005009907A1 (en) * 2003-07-24 2005-02-03 Knutsen Oas Shipping As Method and device for removal of gases from water
WO2006137121A1 (en) * 2005-06-20 2006-12-28 Ohr Laboratory Corporation Ballast water treating apparatus
WO2007049139A2 (en) * 2005-10-28 2007-05-03 Resource Ballast Technologies (Proprietary) Limited Method and apparatus for water treatment to eliminate aquatic organisms by an abrupt pressure reduction

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010149638A1 (en) 2009-06-23 2010-12-29 Desmi Ocean Guard A/S Ballast water treatment
WO2011105911A1 (en) 2010-02-24 2011-09-01 Knutsen Ballastvann As Method and device for treatment of water
CN102770341A (en) * 2010-02-24 2012-11-07 克努森压舱水公司 Method and device for treatment of water
JP2013520312A (en) * 2010-02-24 2013-06-06 クヌートセン バラストバン エーエス Method and apparatus for water treatment
US8500995B2 (en) 2010-02-24 2013-08-06 Knutsen Ballastvann As Method and device for treatment of water
CN102770341B (en) * 2010-02-24 2016-01-20 克努森压舱水公司 For the method and apparatus of water treatment
NO20200388A1 (en) * 2019-04-03 2020-10-05 Knutsen Tech As An arrangement and a method for reducing a content of dissolved gas from a gas-containing liquid
WO2020204726A1 (en) * 2019-04-03 2020-10-08 Knutsen Technology As An arrangement and a method for reducing a content of dissolved gas from a gas-containing liquid
NO346293B1 (en) * 2019-04-03 2022-05-23 Knutsen Tech As AN ARRANGEMENT AND A METHOD FOR REDUCING A CONTENT OF DISSOLVED GAS FROM A GAS-CONTAINING LIQUID

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Publication number Publication date
NO20074154L (en) 2009-02-16

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