METHOD AND PLANT FOR PURIFICATION OF OIL-CONTAMINATED BILGE AND SLUDGE WATER ON A SHIP, AND SHIP EQUIPPED WITH SUCH PLANT

• US 20120160660A1
• Filed: 01/25/2012
• Published: 06/28/2012
• Est. Priority Date: 07/27/2009
• Status: Active Grant

• Current Assignee: PPM-Clean AB
• Original Assignee: ppmClean Ab
• Inventors: Karlström, Benny, Hedkvist, Jan
• Granted Patent: US 8,696,873 B2
• Time in Patent Office: Days
• US Class Current: 203/3
• CPC Class Codes: B01D 1/0058 Use of waste energy from other processes or sources, e.g. combustion gas for water treatment C02F1/16
• CPC Class Codes: B01D 1/16 by spraying B01D1/22 takes precedence
• CPC Class Codes: B63J 4/004 for treating sludge, e.g. tank washing sludge
• CPC Class Codes: C02F 1/16 using waste heat from other processes
• CPC Class Codes: C02F 1/40 Devices for separating or removing fatty or oily substances or similar floating material cleaning or keeping clear the surface of open water from oil or like materials E02B15/04; devices in sewers for separating liquid or solid substances from sewage E03F5/14, e.g. for use in drains leading to the sewer E03F5/16
• CPC Class Codes: C02F 2103/008 Originating from marine vessels, ships and boats, e.g. bilge water or ballast water

Abstract

The present invention relates to a method for purification of bilge and sludge water on a ship, especially at sea, using excess heat from the ship'"'"'s engine(s) to a level of oil contamination of less than 15 ppm. The invention also relates to a plant for carrying out the method, and a vessel including such plant, as well as the use of the method and plant.

Claims

1. A method for purification of sludge water and/or bilge water on a ship using excess heat from the ship'"'"'s engine(s) to provide the necessary heating, comprising the steps of

(a) heating of oil-contaminated water;

(b) evaporating the water at a sub-atmospheric pressure;

(c) condensing the water;

(d) measuring the level of oil-contamination in the water obtained in step (c) as compared to a certain tolerable maximum upper limit;

(e) withdrawing oil sludge obtained in step (b) from the process;

(f) optionally discharging at sea water not exceeding the upper limit as measured in step (d),

characterised in that

any water exceeding the upper limit in step (d) is re-circulated back to step (a), in that steps (a) and (b) occurs at different locations, in that in step (b) oil-contaminated water entering step (b) is finely divided into droplets, and in that particles and/or aerosols obtained in step (b) are separated from the water vapour obtained in step (b).

2. The method of claim 1, wherein the velocity of the liquid flow through the heat exchanger is sufficiently high to achieve a turbulent flow over the heat exchanging surfaces of the heat exchanger, thereby minimizing the extent of formation of deposits on the heat exchanging surfaces.

3. The method of claim 1, wherein withdrawal of the liquid phase from the bottom of the evaporation chamber is sufficiently rapid so as to minimize the extent of formation of deposits on the internal surfaces of the evaporation chamber.

4. The method of claim 1, wherein cooling water from the ship'"'"'s engine(s) is supplied to the heat exchanger as the heating medium.

5. The method of claim 1, wherein the oil-contaminated water fed to the process is taken directly from the sludge water and/or bilge water tank without any preceding purification step.

6. The method of claim 1, wherein after step (c) the water is led through an activated carbon filter before measurement is carried out in step (d).

7. The method of claim 1, wherein condensed low density oil is separated out from the process in step (c).

8. A plant for carrying out the method of claim 1 comprising an evaporation chamber for evaporation of water, one or more nozzles in the evaporation chamber for injection of oil-contaminated water, a heat exchanger for heating oil-contaminated water which is external to the evaporation chamber, a circulation pump for circulating liquid from the bottom of the evaporation chamber back to said heat exchanger for heating oil-contaminated water, vacuum means for producing a sub-atmospheric pressure in the evaporation chamber, characterised in further comprising a condenser for condensing the water vapour led out from the evaporation chamber, a condensate tank for holding condensed water obtained in the condenser, a demister which is located in the evaporation chamber above said one or more nozzles, an oil gauge for measuring the level of oil-contamination in the water obtained from the con-denser, and means for recirculating condensate water having a too high concentration of oil back to the heat exchanger for heating oil-contaminated water.

9. The plant of claim 8, wherein the bottom of the evaporation chamber is essentially conical.

10. The plant of claim 8, further comprising an activated carbon filter.

11. The plant of claim 8, further comprising separation means for separating out condensated low density oil.

12. The plant of claim 8, wherein evaporation chamber is provided with means for eliminating splashing or washing of the liquid phase in said chamber.

13. The plant of claim 8, wherein a restrictor valve for restricting the flow of heated oil-contaminated water exiting the heat exchanger fed to the one or more nozzles is provided on the conduit leading from the heat exchanger to the evaporation chamber.

14. A vessel equipped with the plant of claim 8.

15. The vessel of claim 14, wherein an existent bilge water tank in the vessel is used for holding water of a level of an oil contamination of 15 ppm or lower.

16. Use of the method of claim 1 for purifying oil-contaminated water on a ship at sea during heavy sea.

17. Use of the method of claim 1 for purifying on a ship oil-contaminated water to an oil-content of below 15 ppm and/or for reducing on a ship the content of heavy metals in oil-contaminated water.

18. Use of the plant of claim 8 for purifying oil-contaminated water on a ship at sea during heavy sea.

19. Use of the plant of claim 8 for purifying on a ship oil-contaminated water to an oil-content of below 15 ppm and/or for reducing on a ship the content of heavy metals in oil-contaminated water.