WO2005090151A1 - A method and a plant for purification of oil-contaminated bilge water and ship equipped with a plant for purification of blige water - Google Patents

A method and a plant for purification of oil-contaminated bilge water and ship equipped with a plant for purification of blige water Download PDF

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Publication number
WO2005090151A1
WO2005090151A1 PCT/SE2005/000369 SE2005000369W WO2005090151A1 WO 2005090151 A1 WO2005090151 A1 WO 2005090151A1 SE 2005000369 W SE2005000369 W SE 2005000369W WO 2005090151 A1 WO2005090151 A1 WO 2005090151A1
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WO
WIPO (PCT)
Prior art keywords
water
boiler
oil
tank
plant
Prior art date
Application number
PCT/SE2005/000369
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English (en)
French (fr)
Inventor
Hans Sivertsson
Original Assignee
Hans Sivertsson
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 Hans Sivertsson filed Critical Hans Sivertsson
Priority to EP05722215A priority Critical patent/EP1727730A1/en
Publication of WO2005090151A1 publication Critical patent/WO2005090151A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
    • B01D17/02—Separation of non-miscible liquids
    • B01D17/0208—Separation of non-miscible liquids by sedimentation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D1/00—Evaporating
    • B01D1/02—Evaporators with heating coils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
    • 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
    • B63J4/004—Arrangements of installations for treating ballast water, waste water, sewage, sludge, or refuse, or for preventing environmental pollution not otherwise provided for for treating sludge, e.g. tank washing sludge
    • 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

Definitions

  • the present invention relates to a method and a plant for purification of oil- contaminated water, in particular oil-contaminated bilge water.
  • the present invention also relates to a ship equipped with a plant for purification of oil-contaminated water, in particular oil-contaminated bilge water.
  • the present invention relates to purification of bilge water, in particular purification of bilge water on a ship at sea.
  • Large amounts of oil are used for various purposes on ships, such as a cargo-ships. Examples of used oils are heavy oil, lubricating oil and diesel oil.
  • the so called heavy oil (or heavy fuel oil) is a low grade oil often used as fuel for ships, and is combusted in the main engine of the ship. Since heavy oil is not liquid at room temperature, it must first be heated in order to be used as a fuel.
  • On ships at sea, there are also large water flows, particularly cooling water flows. Often, several separate cooling water systems exist. For example, ships usually have a so called HT- system (HT High Temperature) for the cooling of the ship's main engine or engines.
  • HT- system High Temperature
  • LT-system Low Temperature
  • LT Low Temperature
  • another water flow may be a sea water flow that is used in heat exchangers to cool the water of the HT-system and the LT-system.
  • a sea water flow is used as an alternative for the LT-system.
  • oil such as heavy oil and lubrication oil.
  • water will leak primarily from the cooling systems of the ship, such as the HT-systeni and the LT-system.
  • sealings In practice, it may however be hard in these contexts to achieve completely tight sealings.
  • Oil and water leaking from their respective systems will flow downwards in the ship and end up in the so called drainage pit.
  • a continuous accumulation of water strongly contaminated by oil, so called bilge water takes place.
  • environmental legislation prohibits discharge of bilge water with oil contents exceeding a certain limit.
  • it is not allowed to discharge bilge water having more than 15 ppm of oil.
  • Yet another requirement for allowing discharge of bilge water, is that the ship is running. If the amount of oil-contaminated water is small, the ship may store it onboard until the ship reaches a harbour. In the harbour, the contaminated water can be pumped out from the ship in order to be processed by a purification plant on land.
  • the port authorities must accept contaminated water. However, they prefer not to do so.
  • the bilge water When large amounts of bilge water are formed during short time periods, or when the distance to the closest harbour is large, it is not practical to store the bilge water onboard. Then, the bilge water has to be dumped. In order to be able to do that, the bilge water must be purified at sea, such that the oil contents of the discharged water are kept within the specified limits.
  • One method used today is to try to separate oil from water by using the density difference between water and oil.
  • One way of achieving a separation based on density differences is disclosed in US Patent No. 4,299,703. The document suggests a method in which two liquids of different densities are separated by centrifugation.
  • the method can be used on bilge water. It has also been suggested that bilge water can be stored in a tank in which the oil, due to its lower density in relation to water, tends to separate on top of the water. The intention is that water and oil thereafter can be withdrawn separately from the tank, such that the oil is separated from the water. By such methods can be achieved a far-reaching separation of oil and water. It has been shown, however, that it is difficult by such methods to achieve a complete separation between oil and water. In worst case, it may even happen that the water thus purified still contains more oil and/or other contaminants than prescribed by the environmental legislations. In that case, the water can not be heaved overboard without additional purification. It has been suggested in US Patent No.
  • bilge water is led to an evaporator ("Nerdampfer"). A part of the water is evaporated in the evaporator. It is stated that the evaporation of a part of the water results in an increased salt content in the remaining bilge water, and that the increasing salt content in the bilge water results in a water-oil emulsion being broken. Then, bilge water is pumped from the evaporator to a subsequent station (“Feinent ⁇ ler”), in which oil is separated from water by methods said to be conventional.
  • Feinent ⁇ ler a subsequent station
  • the present invention relates to a method for purification of oil-contaminated bilge water.
  • an initial separation step is conducted first, in which a main part of the separation between oil and water is done. It is understood thereby that the main part, i.e. more than 50 %, of the oil, is separated from the water. In preferred embodiments of t e invention, more than 50 % of the oil is separated from the water in the initial separation step. Preferably, at least two thirds of the oil is separated from the water, and even more preferred, at least three fourths of the oil is separated from the water, by the initial separation step.
  • the initial separation step can be performed by methods known per se.
  • the initial separation step is performed by utilising the density differences between oil and water, but the separation step can also be otherwise performed.
  • oil and water can be separated from each other by binding the oil to a heavier substance that sinks to the bottom of a tank, pulling the oil with it.
  • a boiler is further provided. Water purified in the initial purification step is supplied to the boiler, such that the boiler is at least partly filled by water.
  • Water in the boiler is heated such that at least a part of the water in the boiler evaporates and leaves the boiler, and at least a part of the remaining contaminants sink to and settle at the bottom of the boiler.
  • the contaminants that have sunk to the bottom are discharged from the bottom of the boiler.
  • all or essentially all of the water supplied to the boiler is evaporated, where after the thus evaporated water is led away from the boiler.
  • the water that has left the boiler is continuously replaced by new water having gone through the initial separation from oil, such that the water level in the boiler remains constant at least during a period.
  • the water level in the boiler is constant or essentially constant during the entire time of the process.
  • the boiler may be arranged to communicate with a control tank from which new water can be supplied to the boiler. Then, the water level in the boiler can be controlled by regulating at least one of a supply of water to the control tank, and a removal of water from the control tank.
  • the control tank may suitably be connected, via at least one valve, to a settling tank in which initial separation of oil and water takes place by utilising the density difference between oil and water. Then, water having undergone an initial purification by utilisation of the density difference, can be led from a lower part of the settling tank to the control tank. It is realised that the settling tank can be replaced or supplemented by a device that conducts an initial separation according to other principles.
  • the settling tank can be replaced or supplemented by a device that separates oil and water by centrifugation.
  • water can be led in separate steps from the settling tank to a buffer tank, and from the buffer tank continuously to the control tank.
  • the method is primarily intended to be used on a ship, in which case the water evaporated from the boiler is removed from the ship. It is to be understood however, that the method can be applied also in connection with plants on land, having received contaminated bilge water from a ship, for example.
  • the evaporated water from the boiler is condensed and is led overboard as a liquid.
  • water in the boiler can be evaporated by being heated by heat from the propulsion of the ship.
  • a continuous evaporation and a continuous supply of new water to the boiler is conducted.
  • the invention also relates to a plant for purification and removal of oil-contaminated bilge water.
  • the plant according to the invention comprises a boiler in which contaminated water can be separated by evaporation from remaining contaminants such as oil residues and chemicals.
  • the plant also comprises a condenser for condensing water evaporated in the boiler, as well as a discharge conduit for the removal of water condensed in the condenser, hi advantageous embodiments, an oil gauge (particularly a ppm gauge) may be arranged in connection with the discharge conduit. It should also be noted in this connection that it normally is a requirement according to current law and regulations that an oil gauge is connected to the discharge conduit.
  • the boiler is provided with an inlet for receiving contaminated water, as well as an outlet for contaminants, which outlet is positioned at the bottom of the boiler.
  • the plant may comprise a control tank connected to the inlet of the boiler such that the control tank and the boiler form communicating vessels.
  • control tank may be provided with means for controlling a liquid level in the control tank, such that the water level in the boiler can be controlled by controlling the water level in the control tank.
  • the plant comprises a settling tank in which initial separation of oil and water can take place by utilising density differences between oil and water. Then, the settling tank is connected to the control tank via a lower outlet, and via an upper outlet to an oil collecting tank.
  • An oil sensor is suitably arranged in connection with the settling tank, in order to detect whether liquid on a given level of the settling tank is mainly oil or mainly water.
  • the settling tank is preferably arranged such that it can be chosen if one of the upper outlet and the lower outlet is to be opened as a function of a signal from the oil sensor.
  • a buffer tank can be arranged to receive water from the lower outlet of the settling tank, and to continuously discharge water to the control tank.
  • the boiler comprises a helical heating coil positioned to be lying inside the boiler, such that a centre axis for the heating coil is essentially horizontal.
  • the invention can also be defined in terms of a ship that comprises the inventive plant for purification of bilge water.
  • Fig. 1 shows a ship at sea.
  • FFiigg.. 22 is a diagrammatic cross-section of a portion of the ship shown in Fig. 1.
  • Fig. 3 is diagrammatically showing a plant for purification of bilge water.
  • Fig. 4 is diagrammatically and in cross-section showing a detail of the plant shown in Fig. 3.
  • Fig. 5 is diagrammatically showing another detail of the plant shown in Fig. 3.
  • FFiigg.. 66 is diagrammatically showing a second embodiment of a plant for purification of bilge water.
  • Fig. 7 is diagrammatically showing another embodiment of the invention.
  • Fig. 8 is diagrammatically and in cross-section showing a detail of the plant shown in Fig. 3.
  • FFiigg.. 99 is showing a variation of the embodiment shown in Fig. 6.
  • Fig. 10 is showing another variation of the plant shown in Fig. 3.
  • Fig. 11 is diagrammatically showing a component that in advantageous embodiments can be combined with the rest of the equipment.
  • Fig. 12 is schematically showing an alternative embodiment of the detail shown in Fig. 5.
  • a ship 1 is shown at sea.
  • the ship 1 is diagrammatically shown in cross-section.
  • the ship 1 has an engine 37 driven for example by heavy oil or diesel oil.
  • the engine 37 can drive the ship by delivering power to a propeller 38, via a propeller shaft 39.
  • a propeller 38 can drive the ship by delivering power to a propeller 38, via a propeller shaft 39.
  • Fig. 2 it is shown how the engine 37 is partly placed below a floor plate 40 of the ship 1.
  • cooling water systems not shown
  • bilge water Water and oil having leaked out will then flow downwards in the ship 1 and end up in the drainage pit 36 (or drainage pits 36).
  • the oil-contaminated water in the drainage pit 36 is called bilge water.
  • bilge water is led to a bilge water tank 35, which collects bilge water to be purified.
  • bilge water can " be pumped up by a not shown pump, to a so called day tank 29 at a higher position. From the day tank 29, the bilge water can be led to a plant 2 for purification of bilge water.
  • the day tank 29 is connected by a conduit 33 to a settling tank 17.
  • the settling tank 17 can be provided with a float 27, used to monitor the liquid level in the settling tank 17.
  • a valve 32 is opened in order for bilge water to flow via conduit 33 to the settling tank 17.
  • the float 27 is areanged to indicate low level when the settling tank 17 is half empty (i.e. half full).
  • the float 27 can be connected to valve 32, such that valve 32 opens automatically when the float 27 indicates low level.
  • ship personnel reads the indication of the float 27 in order thereafter manually to open or close valve 32.
  • the valve 32 is closed, either automatically or manually.
  • the settling tank 17 is intended to be used for initial separation of oil and water, by utilising the density differences between oil and water. Due to its lower density, the oil will tend to position itself on top of the water, such that the bilge water forms a lower water layer and an upper oil layer. It is realised however that in the normal case, t ie separation is incomplete whereby the water layer may still contain an unacceptably high content of contaminants, such as oil residues as well as other contaminants such as chemicals and heavier particles from the oil.
  • the settling tank 17 is, via at least one lower outlet 18, connected with a control tank 10. Via at least one upper outlet 19 and a conduit 34, the settling tank 17 is connected with an oil collecting tank 20.
  • the upper outlet 19 is intended to serve as an oil outlet, since the oil tends to end up on top of the water.
  • the upper outlet 19 is preferably positioned at a level conesponding to half the height of the settling tank 17, such that oil is drained from the middle of the settling tank 17 and not from the bottom or the upper part of the tank.
  • An oil sensor 21 may suitably be arranged in connection with the settling tank 17, in order to detect whether liquid on a given level of the settling tank 17 is mainly oil or mainly water.
  • the settling tank 17 is ananged such that it can be chosen if one of the upper outlet 19 and the lower outlet 18 is to be opened as a function of a signal from the oil sensor 21. If the oil sensor 21 indicates oil at the predetermined level, a valve 26 is opened which is connected to the upper outlet 19, such that oil may flow from the upper part of the settling tank 17, via the upper outlet 19 and down into the collecting tank 20. If the sensor 21 instead indicates water at the predetermined level, the valve 26 remains closed. Instead, a valve 25 is opened, which is connected to the lower outlet 18, such that water can flow out through the lower outlet 18 and further to the control tank 10.
  • Valves 25 and 26 can be solenoid valves connected to a control and regulation unit, such as a control cabinet or a computer that in advantageous embodiments is also connected to the sensor 21. It is also conceivable that valves 25 and 26 are manually operated after reading of the oil sensor 21. When float 27 indicates that the level is low in the settling tank 17, shutting takes place of the one of valves 25 and 26 that is open at that moment, such that the flow from settling tank 17 ceases. Instead, the settling tank 17 is filled with new bilge water from day tank 29. It is to be understood that normally not more than one of valves 25, 26 is open at any given moment, such that only oil or only water leaves tank 17 at any given moment.
  • valves 25, 26 that is open, such that water and oil, respectively, are altematingly led away from the settling tank 17.
  • a timer (not sho ⁇ vn) can be connected to the plant, in order for the bilge water 17 to get enough time to layer.
  • the timer is part of the same control- and regulation unit that is connected to the oil sensor 21.
  • the timer starts countdown.
  • the timer signals either valve 25 that is connected to the lower outlet 18, or valve 26 that is connected to the upper outlet 19.
  • Which one of the valves 25, 26 that is ordered to open depends on which signal that is received from the oil sensor 21.
  • the time period Ti is suitably set to coreespond to the time it takes for the water in a buffer tank 22 to be drained to control tank 10.
  • the buffer tank 22 and its function will be explained further below.
  • a venting is suitably provided in the top of the settling tank 17.
  • valve 18 for the lower outlet will open, as mentioned above, whereby settling tank 17 starts to be drained of water. Then, valve 26 for the upper outlet 19 is closed. It is realised that there is a layer of oil on top of the water. Accordingly, the oil layer will move downwards when water disappears from the settling tank 17, until the oil sensor detects oil. Then, valve 25 for the lower outlet 18 will close and instead valve 26 for the upper outlet 19 is opened and oil starts to flow through conduit 34 for oil, down to the oil collecting tank 20.
  • the settling tank 17 is relatively high, in order for the layer-forming to get enough time.
  • the settling tank 17 should be of at least 0.5 m height.
  • the settling tank has a height of considerably more than 0,5 m.
  • a height of 1 m, or 2 m, or even more, is conceivable.
  • settling tank 17 can be of a height of considerably less than 0.5 m. Accordingly, the value of 0.5 m is not to be seen as a minimum value, but only as value that denotes what is advantageous.
  • the total volume is also important in order for the time in the settling tank 17 to be long enough to enable efficient layer-forming.
  • the settling tank 17 may have total volume of 20 L. It should be realised however that the settling tank 17 can have a volume less than 20 L, but also a volume considerably more than 20 L. Accordingly, in practicable embodiments the settling tank 17 may have a volume of 20-100 L, e.g. Embodiments are also conceivable in which the volume of the settling tank is considerably more than 100 L, and it may even be of several cubic metres.
  • Fig. 3 shows how the water can flow via conduit 48, to control tank 10.
  • a filter 41 is arranged in connection with conduit 48.
  • the filter 41 is intended primarily to catch any dirt particles that otherwise may clog subsequent valve(s).
  • a throttle valve 24 is arranged in conduit 48, such that water can flow only at limited velocity to the control tank 10.
  • the throttle valve 24 is arranged downstream the filter 41.
  • the throttle valve 24 is adjustable, and it should be set to be open enough for the control tank 10 level to be just below the level of repletion. It may be added that primarily it is the throttle valve 24 that is to be protected by the filter 41.
  • a buffer tank 22 is arranged to receive water from the lower outlet 18 of the settling tank 17, and continuously to discharge water to the control tank 10.
  • the buffer tank 22 is shown in Fig. 3 at the side of settling tank 17. It should be understood however that Fig. 3 is a diagrammatic sketch and that the buffer tank 22 can be positioned also at a lower level than the settling tank 17, partly or completely. For example, buffer tank 22 may be positioned vertically below settling tank 17.
  • Buffer tank 22 acts as a buffer tank when valve 25 for the lower outlet 18 is closed. It is advantageous to position the buffer tank in a position that is as high up as possible, in order to give a uniform pressure for the throttle valve 24 of the control tank 10.
  • the buffer tank 22 volume is at least equally large as the volume of water that can be drained from the settling tank 17 during one cycle.
  • buffer tank 22 has a volume that is at least half of the total volume of settling tank 17.
  • the buffer tank is even larger in relation to the settling tank 17, such that water supply to control tank 10 can be continuous even if during one or more cycles only oil or mainly oil is supplied.
  • control tank 10 is relatively large, whereby it completely replaces the buffer tank 22.
  • control tank 10 should have a volume that is at least half of the volume of settling tank 17.
  • control tank 10 can be provided with a lid (not shown), that can be opened for inspection of control tank 10.
  • Control tank 10 is connected to an inlet 7 of a boiler 3. P eferably, the connection is such that the control tank 10 and the boiler 3 form cornm-Tinicating vessels. Then, the liquid level in boiler 3 will be equal to the liquid level in control tank 10.
  • control tank 10 may be provided with means 11, 12 for controlling a liquid level in the control tank 10, such that the water level in the boiler 3 can be controlled by controlling the water level in the control tank 10.
  • Fig. 8 shows diagrammatically and principally a possible embodiment of a device for controlling the water level in control tank 10.
  • control tank 10 is shown to be provided with a tube
  • socket 12 is suitably adj usted downwards. This is because at high sea, the risk of cascades from boiler 3 increases. Accordingly, in bad weather it may be suitable to adjust socket 12 downwards , such that the liquid level in boiler 3 is lowered.
  • socket 12 can be adjusted upwards for a more optimal evaporation.
  • connection between the control tank 10 and the boiler- 3, is preferably arranged at the bottom of control tank 10 or lowermost on the side of control tank 10.
  • boiler 3 water that reaches boiler 3 still can be expected to contain contaminants, primarily in the form of oil residues forming an emulsion with water, chemicals and heavy particles from the oil.
  • contaminated water can be separated by evaporation the from remaining contaminants, when heat is supplied to the boiler.
  • the boiler 3 can be provided with a helical heating coil 23 preferably positioned to be lying inside the boiler 3, such that a centre axis for the helical heating coil 23 is essentially horizontal, which is diagrammatically shown in Fig. 4.
  • the present inventor has found that this by this design, the risk of splashes during boiling is diminished in comparison with the case with a standing coil.
  • the invention can be practiced also with a standing heating coil 23, and also with other types of heating devices.
  • Most ships have a steam surplus from the flue gas boiler, and excess steam may be used for heating the heating coil 23. If dirt (such as oil residues) gets burned and sticks to the heating coil 23, this may negatively affect the function of the heating coil 23. Therefore, it is suitable from time to time to clean the coil 23.
  • This can be done by mechanical cleaning e.g., or by ultrasound.
  • a brush can be used for mechanical cleaning.
  • Such a brush can be automatic, and be fixedly arranged in connection with coil 23.
  • An automatic brush can for example be controlled electrically or pneumatically. It should be realised that other types of cleaning devices than brushes can be provided in connection with the coil 23.
  • a condenser 4 is arranged above boiler 3, in order to receive and condense water evaporated in the boiler 3.
  • condenser 4 has a cooling coil (not shown) to cool down water evaporated from boiler 3.
  • a cooling medium for the cooling coil may be sea water, e.g.
  • Fig. 3 shows how an oil gauge 6 is arranged in connection with a portion 5b of the discharge conduit.
  • the oil gauge 6 is advantageous and is included in prefened embodiments of the invention. Embodiments without the oil gauge in discharge conduits 5a, 5b, are however also conceivable.
  • the object of oil gauge 6 is to control that the water does not have a prohibited high amount of oil. It is to be realised that the oil gauge 6 can be seen more generally as a gauge for contaminants in general, and not only for oil.
  • the boiler 3 is formed with an inlet 7 to receive contaminated water. Moreover, the boiler 3 has an outlet 8 for contaminants, such as oil residues and heavy particles from the oil, which outlet 8 is positioned at the bottom 9 of boiler 3.
  • the boiler 3 has a safety valve 28 that is able to handle a free flow of steam from a broken heating coil 23, e.g.
  • the plant according to the invention operates in the following way.
  • Contaminated water is supplied to the boiler 3, such that boiler 3 is at least partly filled with water.
  • the contaminated water in the boiler 3 is heated in order to evaporate at least a part of the water in the boiler 3, in order to leave the boiler 3.
  • the present inventor has found that thereby, at least a part of the contaminants in the water will sink to the bottom 9 of the boiler 3, and settle on the bottom 9 of the digester 3 as a sediment of contaminants, in particular an oil sediment. Instead of lying as a top layer, the contaminants will accordingly sink to the bottom. Thereafter, the contaminants can be lead away from the bottom 9 of boiler 3.
  • Fig. 3 shows how a valve 31 is provided in connection with the oil outlet 8 on the bottom 9 of the boiler 3.
  • valve 31 is a valve that can be rapidly opened and shut, and that has a relatively large area, such that outlet 8 can be open during a short time, for example for 0.5-3 seconds, whereby contaminants on the bottom 9 of boiler 3 can be rapidly drained from boiler 3, optionally by aid of a certain overpressure inside boiler 3.
  • each moment of opening should not be longer than two seconds.
  • the valve area area accessible for flowing through
  • a rapid draining can be achieved without an inner overpressure in boiler 3.
  • the present inventor in one embodiment has considered a valve with an opening of 15 mm in diameter. Of course, other sizes are conceivable.
  • the draining from boiler 3 can preferably be automatic and optionally be controlled by a timer (not shown).
  • water that leaves boiler 3 is continuously replaced by new water, such that the water level in boiler 3 remains constant or constant at least for a period.
  • the supplied contaminated water is continuously boiled, so that essentially all water that is supplied to boiler 3 is evaporated and separated from the oil and/or other contaminants, where after the thus evaporated water is led away from boiler 3.
  • a constant water level in boiler 3 can be achieved as boiler 3 is arranged to communicate with control tank 10, from which new water can be supplied to boiler 3.
  • the water level in boiler 3 can be controlled by regulating at least one of a supply of water to control tank 10, and a removal of water from control tank 10. Removal of water can for example be controlled by the arrangement shown in Fig. 8.
  • Supply of water to tank 10 can be controlled e.g. by controlling by the throttle valve 24 shown in Fig. 3.
  • control tank 10 is communicating with settling tank 17, via at least one valve 24. It is realised that water is led in separate steps from settling tank 17 to buffer tank 22, and continuously from buffer tank 22 to control tank 10.
  • Fig. 5 shows schematically how steam V passes a labyrinth seal 30 on its way from boiler 3 to condenser 4.
  • the object of labyrinth seal 30 is to prevent contaminated water from splashing up into condenser 4 during boiling. As mentioned above, the risk therefore increases in connection with heavy seas. It is prefened that only steam V makes its way to condenser 4.
  • Fig. 3 shows that the condenser has a conduit 5 for discharge of condensed water.
  • Fig. 3 shows conduit 5 divided in an upstream portion 5a and a downstream continuing portion 5b.
  • the water can be made to pass an additional filter 44.
  • the upstream portion 5 a of conduit 5 leads to a condensate tank 43.
  • FIG. 3 shows how an oil gauge 6 is provided in a portion 5b of conduit 5 positioned downstream condensate tank 43. If oil gauge 6 indicates that the oil content is within allowed limits (it is most often required that the oil content should be below 15 ppm), the condensed water can be led to an outlet 45 where it is heaved overboard, as is also indicated in Fig. 1.
  • Reference numeral 75 indicates an overboard valve. According to the regulations, purified bilge water can only be heaved overboard from a running ship. The time, the position of the ship and the amount of water that is let out, must be noted. The pumping out of purified bilge water can be automatic or manual. If the oil content is above the allowed limit, water can be sent to the bilge tank 35. Fig.
  • FIG. 3 shows oil gauge 6 positioned downstream condensate tank 43. It should be realised however that the oil gauge 6 can be positioned between condenser 4 and condensate tank 43. Fig. 3 shows that the discharge conduit 5a continues 5b downstream the condensate tank 43, and that the oil gauge 6 is positioned in the continuing portion 5b. As is evident from above, embodiments are however also conceivable in which the oil gauge 6 is positioned in the portion 5a of discharge conduit that is upstream condensate tank 43.
  • Fig. 11 shows diagrammatically another oil separator 80 that can be used in preferred embodiments of the invention.
  • the oil separator 80 is shown as a vessel 80 suitably positioned in conduit 5a, between condenser 4 and filter 44 in the embodiments shown in Figs. 3, 6, 9 and 10.
  • vessel 80 suitably positioned in conduit 5a, between condenser 4 and filter 44 in the embodiments shown in Figs. 3, 6, 9 and 10.
  • water comes from condenser 4
  • a venting pipe in the top of vessel 80 is denoted 86. Oil can be drawn from layer 81 via a conduit 84 provided with an openable valve 83.
  • a venting pipe 87 may also be present in conduit 5a downstream vessel 80.
  • Fig. 12 shows diagrammatically an alternative to the labyrinth seal shown in Fig. 5.
  • Fig. 12 shows a water separator comprising a vessel 90 with holes 91.
  • vessel 90 When it is used, vessel 90 is positioned inside boiler 3.
  • the water separator also has a funnel-shaped part 92, the funnel of which faces downwards.
  • steam will rise up from the liquid surface LL and go into vessel 90, via holes 91. Then, the steam turns downwards and thereafter upwards, through the upside-down funnel 92. If any contaminated water has entered through holes 91, it is drained back via conduit 93 leading from the bottom of vessel 90 and down below the liquid surface LL in boiler 3.
  • the water separator shown in Fig. 12 can be used in all shown embodiments. It is also realised that it can be used independent of if an oil separator as shown in Fig. 11 exists or not.
  • the method is primarily intended to be used on a ship 1, in which case the water that is evaporated in boiler 3 is removed form the ship 1. h advantageous embodiments of the invention, this takes place by the evaporated water from the boiler 3 being condensed and led overboard as a liquid. It is also conceivable however, that the evaporated water is not condensed but is led overboard as a steam. It should also be realised that the inventive method need not be used on a ship 1, but that the method can be used on land as well. Also, the inventive method and the inventive plant can be used on a rig such as
  • the settling tank 17 as well as the condensate tank 43 could have a volume in the magnitude of about 20 L, while the buffer tank 22 could be of somewhat smaller volume.
  • the total height of the plant could be 1-2 m. It should also be understood however that in each individual case, the dimensioning should be adapted to circumstances, and the dimensions mentioned above should only be seen as possible examples.
  • bilge water is evaporated in boiler 3 by being heated by waste heat from the ship's main engine(s) and or auxiliary machines. It is also conceivable however to use one or more separate heat sources to heat the bilge water. Above, the method has been described as a method in which contaminated water is evaporated in a continuous process. It should be understood however, that variants are conceivable, in which water is batch- wise evaporated in the boiler 3.
  • the boiler 3 can be provided with a tube for flushing the walls 3 clean by pure water or some other suitable liquid.
  • Fig. 3 shows that boiler 3 and condenser 4 are separated from each other by a certain distance. Accordingly, the condenser 4 is not shown to rest on boiler 3. Thereby, heat exchange from boiler 3 to condensed water in condenser 4, is avoided.
  • Such a design may be advantageous, since it has been shown that the function of the oil gauge 6 may be interfered with if the water passing the oil gauge 6 is of too high a temperature. Some other type of thermal insulation between boiler 3 and condenser 4 is also conceivable.
  • Another way of keeping down the temperature of the water passing the oil gauge 6, can be to cool the water down before it reaches oil gauge 6.
  • the inventive plant 2 can be provided with a cooling device (not shown in the figures), for cooling of the condensed water.
  • a cooling device can be placed e.g. in connection with condensate tank 43.
  • Fig. 6 the day tank 29, the settling tank 17, the boiler 3, and the condenser 4, have the same functions as described above with reference to Fig. 3.
  • the day tank 29 is connected to the settling tank 17, via a conduit 33.
  • hi conduit 33 there is a valve 32 that can be opened when the float 27 detects that the level is low in the settling tank 17.
  • the settling tank 17 has a lower outlet 18 that can be opened and closed by a valve 25.
  • the settling tank 17 has an upper outlet 19 that leads to a collecting tank for oil, via a conduit 34.
  • the oil flow through conduit 34 can be shut off or turned on by operation of a valve 26.
  • Fig. 6 The embodiment shown in Fig. 6 is however intended to operate by evaporation in boiler 3 taking place at a pressure below atmospheric pressure.
  • boiler 3 and condenser 4 are connected to a vacuum source, which is shown in Fig. 6 as an ejector 57 connected to an ejector tank 55.
  • Fig. 6 shows that the connection may be provided with a valve 61 , for opening or shutting of the connection.
  • the settling tank 17 is, via a conduit 48, connected to a buffer tank 42 that can also be connected to a vacuum source.
  • Fig. 6 shows how the buffer tank 42 is connected to the same ejector 57 as is boiler 3 and condenser 4, via a conduit 60.
  • a valve 65 in the conduit 60 between buffer tank 42 and ejector 57 can be opened and shut as needed. Via an additional valve 66, the buffer tank 42 can be connected with or isolated from atmosphere.
  • a lower outlet 8 is arranged at the bottom of boiler 3, which outlet leads to a drainage tank 46 for contaminants, such as sediments of oil and heavy particles in the oil.
  • a valve 62 in the conduit from outlet 8 to drainage tank 46 can be opened or shut as needed. Drainage tank 46 can be connected to ejector 57, in order to achieve the same negative pressure in the drainage tank 46 as in boiler 3.
  • Fig. 6 shows that the drainage tank 46 can be connected to ejector 57 or some other vacuum source, via a valve 79.
  • the drainage tank 46 can be disconnected from the ejector 57, the valve 62 can be closed, and the drainage tank 46 can be allowed to change to atmospheric pressure. Via a valve 78 e.g., drainage tank 46 can be connected to or isolated from atmospheric pressure. From drainage tank 46, oil sediment and other contaminants removed from the bottom of boiler 3 can be led to the oil collecting tank 20. For this purpose, there is an openable valve 63 in the conduit between drainage tank 46 and oil collecting tank 20. When drainage tank 46 is below atmospheric pressure, the valve 63 between drainage tank 46 and collecting tank 20 can be opened such that oil sediment from the boiler finally ends up in collecting tank 20. In this embodiment, the method according to the invention operates in the following way.
  • the buffer tank 42 is at atmospheric pressure when liquid is led from settling tank 17 to buffer tank 42. Then, the flow from settling tank 17 is shut off, and buffer tank 42 is connected to a vacuum source, such that the pressure in buffer tank 42 becomes negative. Boiler 3 and condenser 4 are connected to the vacuum source all the time, and hence they are constantly at negative pressures. After the buffer tank 42 has been connected to a vacuum source, a valve 64 is opened in the conduit from buffer tank 42 to the boiler, and the water in buffer tank 42 is led into boiler 3. In boiler 3, water is evaporated at a pressure below atmospheric pressure. Then, evaporation can take place at a lower temperature than if evaporation took place at atmospheric pressure.
  • boiler 3 can be provided with a float 76. Via a cable 77 e.g., the float 76 of boiler 3 may be connected with valve 64 in the conduit from buffer tank 42. When the float 76 indicates low level in boiler 3, valve 64 is opened. It should be understood that float 76 also can be connected to a control cabinet or similar that in turn controls valve 64.
  • the level in boiler 3 may be monitored by other means than a float. Such alternative means can also be connected to valve 64 or a control device that controls valve 64.
  • the method is essentially the same as in the embodiment according to Fig. 3.
  • the discharge conduit 5b leads to an outlet 45, and an oil gauge may be positioned in connection with the discharge conduit.
  • an oil gauge may be positioned in connection with the discharge conduit.
  • the condenser is shown to be positioned directly on top of boiler 3. It is realised that in the embodiment according to Fig. 6, boiler 3 may operate at a lower temperature than in the embodiment according to Fig. 3. Accordingly, there is less effect of heat transfer from boiler 3 to the condensed water, and the risk of interference with the operation of the oil gauge 6 is smaller.
  • Fig. 7 may be suitable for smaller merchant ships or fishing boats.
  • Bilge water can be pumped - possibly by hand - from drainage pit 36 to settling tank 17.
  • the settling tank is left for a while in order for an initial separation to take place by oil and water forming layers, where after oil can be led away via one or more upper outlets 19.
  • water having undergone an initial purification can led away by opening valve 53 and letting out water via at least one lower outlet 18.
  • a funnel 54 can be used to lead the liquid into conduit 49 leading to inlet 7 for boiler 3.
  • boiler 3 and condenser 4 can be connected by an ejector 57 e.g. to a vacuum source, where after evaporation takes place.
  • ejector 57 e.g. to a vacuum source
  • contaminants such as oil residues and heavier particles sink to the bottom of boiler 3 and are withdrawn via outlet 8.
  • Fig. 7 shows that the outlet 8 is connected to a valve 52 that can be opened when contaminants such as oil sediments are to be emptied from the bottom of boiler 3. It is realised that the plant shown in Fig. 7 can operate also at atmospheric pressure, i.e. without ejector 57.
  • the plant shown in Fig. 7 can also have a vacuum pump instead of an ejector 57.
  • a cut-off valve in conduit 49 is indicated by reference numeral 74.
  • Fig. 9 shows a variant of the plant shown in Fig. 6.
  • the plant shown in Fig. 9 differs from that shown in Fig. 6, by replacement of the ejector shown in Fig. 6 with a vacuum pump 70.
  • the plant shown in Fig. 9 is the same as is shown in Fig. 6, and it operates in the same way.
  • Fig. 10 shows a variant of the embodiment according to Fig. 3. h the embodiment shown in Fig. 10, the oil gauge 6 is positioned in the portion 5b of the discharge conduit that is positioned downstream the condensate tank 43.
  • a three way valve 71 is provided downstream oil gauge 6. From the three way valve 71, water can be led either to outlet 45 where the water is heaved overboard, or back to the system, such as back to bilge tank 35.
  • a flow meter 72 can be arranged to measure the amount of water that is heaved overboard through outlet 45.
  • the letter P indicates a pump. Also, in the embodiment shown in Fig.
  • Fig. 10 also symbolically shows an inspection viewer 73 positioned before the three way valve 71.
  • the inspection viewer 73 can be used to show the operation to inspecting authorities.
  • the inspection viewer 73 can also be placed after the three way valve 71, such that the inspection viewer 73 and the three way valve 71 will swap places in the figure. It is to be understood that an inspection viewer 71 may be present also in the embodiments shown in the other figures, and then at positions corresponding to Fig. 10.
  • inventive plant is intended to be used to conduct the inventive method. Accordingly, the inventive method may comprise such steps that follow naturally from use of the inventive plant, independent of if such steps are explicitly mentioned or not.
  • the invention can be defined also in terms of a ship 1 equipped with such a plant 2 for purification of bilge water, as is described above. Furthermore, the invention can be seen in terms of a method of installing the inventive plant on a ship, in which case the method of installation comprises the steps that follow naturally from installing the plant as described above. The invention can also be defined in terms of a rig equipped with the inventive plant.
  • the inventive method and plant can be used independent of the salt content of the water.
  • the advantage is achieved among other things that it is easy by an oil gauge to control that the water that is thereafter heaved overboard is within allowed limits.
  • the initial separation step can be eliminated. Accordingly, the initial separation step may be advantageous, but embodiments of the inventive method are conceivable in which no initial separation step is conducted. It should be realised however that if the initial separation step is excluded, the amount of oil in the boiler will be expected to increase in time. Hence, if the initial separation step is completely eliminated, it is likely that the entire boiler has to be emptied from time to time.

Abstract

SAMMANDRAG Uppfinningen avser en metod för rening av oljekontaminerat länsvatten. Metoden innefattar ett inledande separationssteg där huvuddelen av oljan i länsvattnet separeras från vattnet så att renat vatten erhålles. Det sålunda renande vattnet förs till en kokare där vattnet evaporeras. Metoden innefattar även en anläggning för rening av oljekontaminerat länsvatten samt ett fartyg utrustat med den uppfinningsenliga anläggningen.
PCT/SE2005/000369 2004-03-22 2005-03-16 A method and a plant for purification of oil-contaminated bilge water and ship equipped with a plant for purification of blige water WO2005090151A1 (en)

Priority Applications (1)

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EP05722215A EP1727730A1 (en) 2004-03-22 2005-03-16 A method and a plant for purification of oil-contaminated bilge water and ship equipped with a plant for purification of blige water

Applications Claiming Priority (2)

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SE0400755-5 2004-03-22
SE0400755A SE526811C2 (sv) 2004-03-22 2004-03-22 En metod och en anläggning för rening av oljekontaminerat länsvatten samt ett fartyg utrustat med en anläggning för rening av länsvatten

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009043135A1 (en) * 2007-10-03 2009-04-09 Ian Fielding Wastewater treatment system and method
WO2010030219A1 (en) * 2008-09-11 2010-03-18 Claes Olofsson A method and a device for cleaning of so-called waste oil
WO2011014107A1 (en) 2009-07-27 2011-02-03 Ppmclean Ab Method and plant for purification of oil-contaminated bilge and sludge water on a ship, and ship equipped with such plant
EP2522635A1 (en) * 2011-05-11 2012-11-14 Ekoport Turku Oy A method and an arrangement for treatment of bilge water
FR2976499A1 (fr) * 2011-06-17 2012-12-21 Pierre Yves Morin Procede de traitement des eaux de cales de navires par distillation sous vide.
EP2682372A1 (en) * 2012-07-05 2014-01-08 Faroe Maritime Technic System and method for dewatering oil/water sludge
WO2017008814A1 (en) * 2015-07-16 2017-01-19 Djurhuus Hans Andrias System and method for purification of contaminated liquid
WO2017139866A1 (en) * 2016-02-16 2017-08-24 Ian Fielding Marine-based water processing and disposal system and method
CN110723770A (zh) * 2019-09-29 2020-01-24 南京金陵船厂有限公司 一种环保节能的滚装船油污水处理方法

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GB847199A (en) * 1958-10-10 1960-09-07 Shell Res Ltd Improvements in or relating to the construction and operation of oil tankers
DE3206253A1 (de) * 1982-02-20 1983-09-01 Marinetechnik Planungsgesellschaft Mbh, 2000 Hamburg Verfahren und vorrichtung zum entoelen von bilgenwasser und dergleichen

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB847199A (en) * 1958-10-10 1960-09-07 Shell Res Ltd Improvements in or relating to the construction and operation of oil tankers
DE3206253A1 (de) * 1982-02-20 1983-09-01 Marinetechnik Planungsgesellschaft Mbh, 2000 Hamburg Verfahren und vorrichtung zum entoelen von bilgenwasser und dergleichen

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2009043135A1 (en) * 2007-10-03 2009-04-09 Ian Fielding Wastewater treatment system and method
WO2010030219A1 (en) * 2008-09-11 2010-03-18 Claes Olofsson A method and a device for cleaning of so-called waste oil
JP2013500203A (ja) * 2009-07-27 2013-01-07 ピー・ピー・エム・クリーン・アクチボラゲット 油で汚染されたビルジおよびスラッジ水を船上で浄化するための方法およびプラント、ならびにこのようなプラントを備えた船
KR20120038536A (ko) * 2009-07-27 2012-04-23 피피엠클린 아베 선박의 오일-오염 빌지수와 폐수의 정화 방법, 정화 장치 및 이를 장비한 선박
WO2011014107A1 (en) 2009-07-27 2011-02-03 Ppmclean Ab Method and plant for purification of oil-contaminated bilge and sludge water on a ship, and ship equipped with such plant
US8696873B2 (en) 2009-07-27 2014-04-15 Ppm-Clean Ab Method and plant for purification of oil-contaminated bilge and sludge water on a ship, and ship equipped with such plant
CN102498036B (zh) * 2009-07-27 2015-12-09 Ppm清洁私人公司 用于净化船上的油污染的舱底水和淤积物水的方法和设备以及装备有这种设备的船
KR101616065B1 (ko) 2009-07-27 2016-04-27 피피엠클린 아베 선박의 오일-오염 빌지수와 폐수의 정화 방법, 정화 장치 및 이를 장비한 선박
EP2522635A1 (en) * 2011-05-11 2012-11-14 Ekoport Turku Oy A method and an arrangement for treatment of bilge water
FR2976499A1 (fr) * 2011-06-17 2012-12-21 Pierre Yves Morin Procede de traitement des eaux de cales de navires par distillation sous vide.
EP2682372A1 (en) * 2012-07-05 2014-01-08 Faroe Maritime Technic System and method for dewatering oil/water sludge
WO2014006122A1 (en) * 2012-07-05 2014-01-09 Faroe Maritime Technic System and method for dewatering oil/water sludge
WO2017008814A1 (en) * 2015-07-16 2017-01-19 Djurhuus Hans Andrias System and method for purification of contaminated liquid
WO2017139866A1 (en) * 2016-02-16 2017-08-24 Ian Fielding Marine-based water processing and disposal system and method
CN110723770A (zh) * 2019-09-29 2020-01-24 南京金陵船厂有限公司 一种环保节能的滚装船油污水处理方法

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SE0400755D0 (sv) 2004-03-22
SE0400755L (sv) 2005-09-23
EP1727730A1 (en) 2006-12-06
SE526811C2 (sv) 2005-11-08

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