KR100935278B1 - Combined exhaust gas-ballast water treatment arrangement and method of treating ballast water - Google Patents

Abstract

The exhaust gas and ballast water treatment apparatus in the ship 1 includes a piping system for generating hot exhaust gas and exhausting the hot exhaust gas, and including a first heat exchanger 6. 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 ') and the first heat exchanger 6 heats the first heat transfer fluid and A first heat exchanger (6) adapted to cool the exhaust gas and a circulation circuit (6.1) for the first heat transfer fluid to be in circulation, wherein the at least one ballast tank (12) and the ballast water distribution circuits (9, 9) Contains'). The ballast water distribution circuit includes a ballast system arranged to be in a heat transfer distribution relationship with the first heat exchanger. The present invention also relates to a method for treating ballast water in a ship 1 using exhaust heat of a heat engine device 2.

Ballast Water Heat Treatment

Description

Combination of exhaust gas-ballast water treatment system and ballast water treatment method {COMBINED EXHAUST GAS-BALLAST WATER TREATMENT ARRANGEMENT AND METHOD OF TREATING BALLAST WATER}

1 is a schematic diagram of an embodiment of a ballast water heat treatment apparatus according to the present invention.

2 is a schematic diagram of another embodiment of a ballast water heat treatment apparatus according to the present invention.

Explanation of symbols for main parts of the drawings

1 ship 2 heat engine device

3: exhaust duct 3.1: chute

3.2 gas outlet 4: exhaust gas boiler

5: exhaust gas silencer 6: first heat exchanger (heat exchange structure)

6.1: First flow circuit (heat exchange structure)

6.2: Gravity Tank (Heat Exchange Structure) 6.3: Nozzle (Heat Exchange Structure)

6.4: second heat exchanger (heat exchange structure) 6.5: collection tank (heat exchange structure)

6.6: Pump (heat exchange structure) 6.7: Piping (heat exchange structure)

6.8: Nozzle device (heat exchange structure) 6.11: Pump (heat exchange structure)

7: shut-off valve                 

9, 9 ': Ballast water distribution circuit (second distribution circuit, heat exchange structure)

11: fourth heat exchanger 12: ballast tank

13, 13 ': intermediate volume 14: fifth heat exchanger

14.1: valve system

The present invention relates to an apparatus for treating exhaust gas and ballast water in a ship according to the preamble of claim 1 and a method for treating ballast water in a ship according to the preamble of claim 12.

Ballast in ships is typically water that will be loaded on board for cargo. This water is used to stabilize the ship by increasing or decreasing its total load and also by adjusting its center of gravity. Ballast is necessary for the safe operation of all types of ships. It is used, for example, for stability, ship balancing and tilt control.

However, the transport of marine species to ballast water in ships is of considerable interest, especially during the long-term voyage of ships carrying a significant amount of ballast water. When such non-indigenous species are introduced into a new environment, they pose a potential threat to the surrounding waters. As a countermeasure therefor, it has been proposed to heat the ballast water. The increase in temperature is considered to cause organically fatal problems, for example in mussel or barnacle varieties.

There may be several ways to heat the ballast water. Firstly, the heat generated by the ship's engine can be circulated to warm the ballast water. This method requires the installation of a heat exchanger in the ballast tank to transfer waste heat from the propulsion system exhaust system or water from the propulsion cooling system to heat the ballast water. Secondly, the ballast water may be circulated and returned into the ballast tank, for example as a part of the engine cooling system, to collect heat in the propulsion engine. This kind of configuration is disclosed in US Pat. No. 5,816,181. However, this publication is an incomplete solution because no disclosure is made regarding the overall control of the heating configuration of the heat engine in the vessel.

It is an object of the present invention to provide a ballast water heat treatment apparatus for a vessel in which the disadvantages of the prior art described above can be minimized and control of thermal balance can be optimized. In addition, another object of the present invention is to provide a composite device of clean exhaust gas and heating ballast water in a ship, so that the available heat can be effectively used.

The objects of the present invention may be disclosed and attained in a more detailed manner in claims 1 and 12 and in other claims.

The exhaust gas and ballast water composite treatment apparatus of a ship according to the first embodiment of the present invention is a heat generating structure including a piping system for generating hot exhaust gas, exhausting the hot exhaust gas, and a first heat exchanger. It is configured to include an engine device. The heat exchange structure includes a circulation circuit for a first heat transfer fluid that is in circulation with a first heat exchanger adapted to heat the heat transfer fluid and cool the exhaust gas. The apparatus also includes at least one ballast tank and a ballast water circulation circuit, the ballast water distribution circuit being arranged to be in a heat transfer distribution relationship with the first heat exchanger. Preferably the first heat exchanger is a direct heat exchanger. The ballast receiving circuit further includes an intermediate volume in front of the ballast in the direction of distribution of the ballast in relation to the ballast water distribution circuit. Preferably the intermediate volume is a tank and / or a pipe of a particular length which is suitably insulated. In this way the ballast water is heat treated, so that some of the water can be treated at once.

The first heat exchanger is a direct heat exchanger. According to one embodiment of the present invention, the ballast water circulation circuit is in a state of being connected to the first heat transfer fluid circulation circuit, so that the first heat transfer fluid, that is, the ballast water, is heated by direct contact with the exhaust gas.

The heat exchange structure has a nozzle apparatus for spraying seawater disposed next to the heat exchanger in the flow direction of the exhaust gas, and the nozzle apparatus communicates with a source of unheated seawater.

According to another embodiment of the present invention, the first circulation circuit is in circulation with a second heat exchanger adapted to cool the first heat transfer fluid and heat the ballast water, the second heat exchanger being an indirect heat exchanger, and thus ballast water Is indirectly heated.                     

The first heat exchanger, ie the direct heat exchanger, is preferably provided with a heat transfer fluid gravity tank adapted to introduce the first heat transfer fluid into the first heat exchanger by gravity. The gravity tank communicates with the seawater through a first distribution circuit, wherein the first heat transfer fluid is configured to extract heat from the cooling system of the heat engine device by a third heat exchanger before it reaches the fluid gravity tank from a source of unheated seawater. do. In addition, the ballast water distribution circuit is provided with a fourth heat exchanger adapted to extract heat from the cooling system of the heat engine device. As a result, the temperature of the ballast water is further increased.

The ballast water to be treated is preferably preheated by the ballast water already treated. Therefore, when the water from the first ballast tank is sent to the second ballast tank by the pumping action and heat exchanges between them, it is advantageous to provide a fifth heat exchanger in the ballast circulation circuit, which is the It is connected to the rear side, and is also connected before the heating of the heat exchanger on the other flow side of the heat exchanger and between the ballast tank and the heat exchanger where water is pumped on the other flow side. The already treated hot ballast water is thus cooled by heating the cold ballast water to be treated and the overall efficiency is increased.

According to the ballast water treatment method in a ship including a piping system for generating hot exhaust gas and exhausting the hot exhaust gas, and including a heat engine device having a heat exchange structure, when supplying the ballast water into the ballast tank. The heat transferred from the exhaust gas is transferred to the ballast water, thereby heating the ballast water from the first temperature to the second elevated temperature. Further, after storing heat in the heat exchanger, the ballast water is maintained at an elevated temperature for a predetermined selected time before supplying the ballast water and before mixing with colder water in the ballast tank. This can be achieved, for example, by passing water through an area with increased fluid cross-sectional area to temporarily reduce the flow rate of water. This area is preferably a tank.

According to the method of the present invention, the ballast water and the exhaust gas are preferably heat exchanged directly with each other in the heat exchanger.

In addition, the introduction of ballast water can be controlled by maintaining the surface height of the water at a desired level in a gravity tank adapted to introduce water into the heat exchanger.

(Example)

Fig. 1 discloses a basic outline showing how the ballast water is efficiently treated, that is, how the heat treatment is performed simultaneously with the cleaning of the exhaust gas. The ship 1 is provided with a heat engine device 2 such as a diesel engine as a main propulsion engine. There are many kinds of such engines. From the diesel engine, the exhaust gas is first introduced by means of an exhaust duct 3 into an exhaust gas boiler 4, which can be provided if necessary, and is firstly mounted horizontally via an exhaust gas silencer 5 (6) (this is a direct heat exchanger, hereinafter referred to as a scrubber). In the embodiment shown in FIG. 1, in the scrubber 6, the exhaust gas is cooled and purified using seawater, and the seawater is heated by hot exhaust gas instead. In the scrubber 6, the sea water is sprayed into the exhaust gas in a suitable manner. Horizontal scrubbers are particularly advantageous because there is no need to pull the water to be heated to a higher position on top of the vessel, which has a positive effect on the stability of the vessel 1.

The final end of the exhaust duct 3 is a chute (3.1), which extends vertically above the bulkhead deck and then downwards back toward the plurality of outlets (3.2), down to the lowest one of them. Is extended. The number of gas outlets 3.2 can be selected as needed, but for example from one to four or five. The highest position of the outlets may be located high enough to allow gas to be discharged under any extreme conditions, for example when the waves are severe or under conditions where the hull breaks beyond the design draft line. The lowest of these outlets is, for example, ballast water lines to allow a maximum vertical distance between the outlet 3.2 and the source standing on the stern mooring deck during operation in a ballast condition. water line). Appropriate heights can be chosen to avoid the release of gas in the port and during entry and departure from disturbing those standing at the docks. For main engines, the lowest outlets 3.2 can be made, usually in size, corresponding to the smallest gas emissions that can be foreseen in ship navigation. A shutoff valve 7 is provided at the outlet 3.2.

The ship may be provided with a gas outlet 3.2 on the starboard and the port side as shown in FIG. 1 as needed. The exhaust duct 3 for the starboard and the port side outlet is provided with a switching valve system 6.9 for controlling the flow of the exhaust gas to direct the flow of the exhaust gas to either or both of the starboard and the port. The changeover valve system 6.9 can be controlled automatically by, for example, a wind direction sensor or other suitable means (not shown). This embodiment of the present invention has an additional advantage, since the position of the gas outlet to be used can be elastically selected. For example, the back pressure of the engine 2 can be reduced by directing gas towards the lower outlet of the vessel. The exhaust duct may also comprise branching pipes 3.3 and 3.4 from the top of the ship to the atmosphere.

The heat treatment of the ballast water is accomplished by using waste heat discharged by cleaning the exhaust gas in the scrubber 6. As shown in FIG. 1, the scrubber 6 has several functional steps 6. 1 and the heat exchange structure comprises two heat transfer fluid circulation circuits. First, the hot exhaust gas is cooled using the first circulation circuit 6.1. The first distribution circuit 6. 1 comprises a piping system for first sending the sea water to the gravity tank 6. 2, wherein the sea water as a heat transfer fluid from the gravity tank is introduced into the scrubber through the nozzle 6. It is also possible to provide a third heat exchanger 10 to preheat seawater in order to extract heat from the cooling system of the heat engine device 2 before reaching the fluid gravity tank 6.2. The scrubber which concerns on one Embodiment of this invention is comprised so that spray of water may be adjusted by maintaining the moderate height of the water surface in a gravity tank, providing constant water pressure, and water is introduce | transduced into a scrubber suitably by this. The pressure in the gravity tank 6.2 is preferably maintained at the ambient pressure level, ie the atmospheric pressure level. By this arrangement, it is possible to maintain a constant pressure, and thus a controlled flow of water, by the use of gravity. In case of sudden loss of pump pressure or temporary malfunction, the gravity tank is adapted to reliably supply water to the scrubber for a period of time to avoid overheating of the pipe downstream of the scrubber 6.

The water to the nozzle device 6.8 of the last stage in the direction of gas flow is preferably supplied directly from the branch pipe of the seawater pump 8 for a surely low gas outlet temperature. Optionally, a separate pump 8.1 can be provided at this last stage. Seawater is collected from the seawater box 15 of the ship. For simplicity, only one sea box is used as an example, but it is clear that multiple sea boxes may be used.

Water flows out of the scrubber 6 into all heat transfer stages other than the final sea water cooling stage, passing through the second heat exchangers, i.e. indirect heat exchangers 6.4, whereby the heat is cooled and the heat is removed. The second heat transfer medium flowing through the second circulation circuit 9 is transferred to the ballast water. Seawater enters the collection tank (6.5) via the heat exchangers, and water is discharged out of the ship by the pump (6.6) from the collection tank. The water may also be recycled to the original gravity tank 6.2 by a pipe 6.7 with a circulation pump 6.11. Although the final temperature of the said scrubber water is about 60-70 degreeC, it is preferable to set it as the temperature at which evaporation is minimum.

The various stages of the second heat exchanger 6.4 and the scrubber, which are indirect heat exchangers, are operated according to a counter-flow method, in order to obtain the best possible heating effect. This means that the first stage of the scrubber heats the second heat transfer fluid, ie the final stage of the ballast water.

In some applications, it may be advantageous to heat the ballast water further, so that a fourth heat exchanger 11 is provided which is adapted to extract heat from the cooling system of the heat engine apparatus for heating the ballast water. In particular, the cooling system of the internal combustion piston engine is a high temperature circuit for cooling the cylinder block and head, for example. This is particularly advantageous when the sailing ship for a short time, that is, the available time for heating the ballast water is limited. The ballast water is heated to approximately 40 to 60 ° C., depending on the desired treatment temperature, for example the available treatment time. As shown in FIG. 1, the heated water enters the tank as an intermediate volume 13 between the fourth heat exchanger 11 and the ballast tank 12. The intermediate volume 13 is configured such that the dwell time of the ballast water under elevated temperature is sufficient to destroy unwanted species in the ballast water. Although the required residence time is strongly dependent on temperature, the treatment should last from at least several tens of seconds to several minutes. In FIG. 1, an increase in the residence time is achieved by the intermediate volume 13, which is a tank, but in some cases it may be replaced by a suitably insulated pipe of sufficient length, as shown, for example, in FIG.

After the heat treatment for a sufficient time, the ballast water can be cooled before going to the ballast tank 12. This means that one flow side is located between the second heat exchangers, that is, the indirect heat exchangers and the ballast tank 12, and the other flow side is located between the intermediate volume 13 and the ballast tank 12. 14) can be achieved. The flow of the ballast water is controlled by the valve system 14.1. In this way, the cold ballast water to be treated is preheated before reaching the second heat exchanger 6.4 and the treated ballast water is cooled to reach the ballast tank 12. In other words, the ballast water is only temporarily heated for the purpose of decontamination.

Valves for determining the direction of the coolant of the engine 2 in order to control the height of the sea level in the gravity tank 6.2 and to direct the sea water from the heat exchanger 10 towards the gravity tank or back to the sea ( 8.2) is installed. Each stage of the scrubber may be connected to the ship's air conditioning system, thereby allowing the nozzle to be cleaned with compressed air (not shown).

The configuration of the present invention can be applied to all ships producing hot exhaust gases such as, for example, main diesel engines, auxiliary diesel engines, gas turbines, oil boilers and incinerators.

An additional advantage of the present invention is that in the scrubber 6 the sulfur oxides are cleaned to a considerable extent from the exhaust gas. The use of suitable additives in the system can further enhance the sulfur oxide removal effect. Additives can be introduced, for example, into the gravity tank 6. 2 through an additive connection 6. 10 and the water suspension formed is sprayed onto the gas stream in the scrubber 6. Such additives may be selected from the group consisting of generally known reactants used to reduce gaseous emissions, for example lime or the like. Particles are efficiently cleaned by the water sprayed. It is also possible to use scale crust prevention additives in this configuration.

Alternative ballast water circulation principles used in the present invention include:

1. Exchange, single pipe. One ballast tank is drained outboard at a time and then refilled via a heat treatment structure.

Discharge and filling cannot be done simultaneously.

2. Exchange, double pipe. While draining one ballast tank outboard at a time, the other tank is filled via a heat treatment apparatus.

Discharge and charge are possible at the same time.

3. Tank to Tank Circulation. It is sucked from one tank and discharged to another tank via a heat treatment apparatus.

This kind of water cycle is shown in FIG. 1.

4. Individual tank circulation. Suction from one tank is returned to the original tank via the heat treatment apparatus.

2 shows another embodiment of the ballast water heat treatment apparatus according to the present invention. This embodiment basically corresponds to that shown in FIG. 1, but does not allow the exhaust gas to be changed to something that is relatively clean or excessively aggressive or corrosive when sprayed with gas in the scrubber 6. It is for use in connection with such a heat engine device for exhausting exhaust gas. Hereinafter, with reference to FIG. 2, the characteristic different from the apparatus of FIG. 1 is mainly demonstrated. Reference numerals in FIG. 2 are used as in FIG. 1 as much as possible.

In the configuration shown in FIG. 2, the ballast water is arranged to be in direct contact with the exhaust gas from the heat engine device 2. In this way the temperature of the ballast water can be higher than the scrubber and indirect heat exchanger coupling method of FIG. The exhaust gas system of the engine is basically the same as in FIG. 1, but the gas outlets 3.2 are shown here only on one side of the vessel 1.

The ballast water to be treated is circulated through the circulation circuit 9 ', which comprises the following components in the direction of circulation of the heat transfer fluid, ie the ballast water. In this case, the ballast water is pumped from the first ballast tank 12 and passes through the fifth heat exchanger 14, and the ballast water to be treated in the fifth heat exchanger is preheated by the already treated ballast water. The preheated ballast water is introduced into a gravity tank (6.2) adapted to introduce the ballast water into a scrubber (6) which is a first heat exchanger, ie a direct heat exchanger. In the embodiment shown in FIG. 2, the ballast water heated in the scrubber 6 is fed to another ballast tank 12 through an intermediate volume 13 ′, which intermediate volume 13 ′ here is of sufficient length. It is a properly insulated pipe. After receiving heat from the scrubber 6, the ballast water is maintained at an elevated temperature for a predetermined selected time and then supplied to the ballast tank 12, where it is mixed with cooler water in the ballast tank 12. do.

The scrubber 6 comprises a plurality of steps 6122 arranged in series using a countercurrent method. The gravity tank 6.2 can also be divided into a plurality of stages. For example, different flow paths may be selected for nozzles in each stage. Through all the steps, the heated water in one step is collected and pumped to the gravity tank 6.2 of the next step until the temperature of the water is sufficient to destroy the unwanted organism.
There is a nozzle apparatus 6.8 for spraying seawater, which is arranged inside the rear of the scrubber 6 in the flow direction of the exhaust gas, which source of unheated seawater, for example, a seawater box 15 of the ship 1. ) Is in circulation.

delete

The invention is not limited to the disclosed embodiments, and various changes are possible within the scope of the appended claims.

As mentioned above, according to the present invention, there are various advantages. Ballast treatment is based on efficient heat recovery where the plant's overall efficiency exceeds 90%. No chemical is required for the treatment of ballast water. No waste is produced by ballast water treatment. According to the present invention, due to the direct heat exchanger for cooling the exhaust gas of the heat engine device, the emission of the exhaust gas can be lowered, and the visibility of the bridge to the stern is improved. The center of the ship's vertical direction is lower, which also favors the stability of the ship.

Claims (17)

A heat exchange structure (6, 6.1, 6.2, 6.3) comprising a piping system having an exhaust duct (3) for producing hot exhaust gas and exhausting the hot exhaust gas and comprising a first heat exchanger (6); 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 '), comprising a heat engine device 2 provided, The heat exchange structure 6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 'is a first heat exchanger adapted to heat the first heat transfer fluid and cool the exhaust gas. (6) and a first circulation circuit (6.1) for the first heat transfer fluid in circulation; One or more ballast tanks (12) and second flow circuits (9, 9 ') for receiving ballasts, wherein the second flow circuits (9, 9') for ballasts receive heat transfer with the first heat exchanger (6). In the exhaust gas and ballast water composite treatment apparatus of a ship (1) including a ballast system arranged to be in a distribution relationship, The first heat exchanger 6 is a direct heat exchanger, The second circulation circuit (9.9 ') for accommodating the ballast includes intermediate volume portions (13, 13') in which the ballast water is heat-treated, and the intermediate volume portions (13, 13 ') are second distribution circuits for accommodating the ballast. And (9.9 ') disposed between the first heat exchanger (6) and the ballast tank (12) in the flow direction of the ballast water. 2. The ballast according to claim 1, wherein the second circulation circuit (9 ') for ballast communication is in communication with the first circulation circuit (6.1) for the first heat transfer fluid, wherein the first heat transfer fluid is ballast water exhaust gas and ballast. Water complex treatment equipment. 2. Apparatus according to claim 1, wherein said intermediate volume (13, 13 ') is a tank or a thermally insulated pipe. 4. A nozzle device (6.8) according to any one of claims 1 to 3, wherein a nozzle device (6.8) for spraying seawater with exhaust gas is arranged rearward in the flow direction of the exhaust gas in the first heat exchanger (6), The nozzle device (6.8) is a combined exhaust gas and ballast water treatment device for distributing with the source (15) of unheated sea water. 4. The first circulation circuit (6.1) according to any one of claims 1 to 3, wherein the first circulation circuit (6.1) cools a first heat transfer fluid in the first circulation circuit (6.1) and a ballast in the second circulation circuit (9). A second heat exchanger (6.4) adapted to heat water and an exhaust gas and ballast water combined treatment apparatus in circulation. The exhaust gas and ballast water combined treatment apparatus according to claim 5, wherein the second heat exchanger (6.4) is an indirect heat exchanger. 2. The apparatus of claim 1, wherein the first heat exchanger (6) is provided with a heat transfer fluid gravity tank (6.2) adapted to introduce the first heat transfer fluid into the first heat exchanger (6). 8. The heat transfer fluid gravity tank (8) according to claim 7, wherein the heat transfer fluid gravity tank (6.2) is in circulation with the seawater via the first circulation circuit (6.1), and from the unheated source of sea water (15) to the heat transfer fluid gravity tank (6.2). An exhaust gas and ballast water composite treatment apparatus in which heat from the cooling system of the heat engine device (2) is extracted by a third heat exchanger (10) located before the transfer and transferred to seawater as a first heat transfer fluid. The exhaust gas and ballast water composite according to claim 1, wherein the second circulation circuit (9) for receiving ballasts is provided with a fourth heat exchanger (11) adapted to extract heat from the cooling system of the heat engine device (2). Processing unit. 2. The ballast according to claim 1, wherein a fifth heat exchanger (14) is provided in the second circulation circuit (9 ') for receiving the ballast, and the fifth heat exchanger (14) is pumped from the ballast tank (12). In the flow direction of the ballast water sent to the ballast tank while being connected to the portion of the second flow circuit 9 'between the ballast tank 12 and the first heat exchanger 6 in the flow direction of the water. And an exhaust gas and ballast water composite treatment apparatus connected to a portion of a second circulation circuit (9 ') between the intermediate volume (13') and a ballast tank (12). 6. The ballast water according to claim 5, wherein a fifth heat exchanger (14) is provided in the second circulation circuit (9) for receiving the ballast, and the fifth heat exchanger (14) is pumped from the ballast tank (12). The ballast tank 12 connected to the ballast tank 12 and the second heat exchanger 6.4 in the distribution direction of the ballast tank, and at the same time as the ballast tank An exhaust gas and ballast water composite treatment apparatus connected to a part of a second circulation circuit (9) between an intermediate volume portion (13) and a ballast tank (12). A ballast water treatment method in a ship (1) comprising a heat engine device (2) for generating hot exhaust gas, the method comprising a piping system having an exhaust duct (3) for exhausting the hot exhaust gas into the atmosphere And a heat exchange structure (6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 ') including the first heat exchanger (6), and the ballast water is supplied to the ballast tank. In the ballast water treatment method in a ship, when supplied into (12), heat transferred from exhaust gas in the heat exchange structure is transferred to ballast water, whereby the ballast water is heated. In the heat exchange structure (6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 '), ballast water and exhaust gas are contacted in a heat exchange state directly or indirectly, In addition, after receiving heat from the heat exchange structure (6, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 6.10, 9, 9 '), the temperature of the ballast water rises for a predetermined selected time Ballast water treatment method in the vessel (1) is maintained after being supplied to the ballast tank (12), and mixed with cooler water in the ballast tank (12). 13. The ballast water according to claim 12, wherein the ballast water is raised for a predetermined selected time by temporarily reducing the flow rate of the ballast water by passing through the intermediate volume portions (13, 13 ') having an increased fluid cross-sectional area. Method of treating ballast water in a vessel maintained at temperature. 14. A method according to claim 13, wherein the intermediate volume (13, 13 ') consists of a tank or a thermally insulated pipe. 13. The method of claim 12, wherein a first heat transfer fluid is introduced from the gravity tank (6.2) into the first heat exchanger (6), and the introduction of the first heat transfer fluid into the first heat exchanger (6) A method of treating ballast water in a vessel controlled by maintaining the surface height of the first heat transfer fluid in a tank (6.2) at a desired level. A method according to claim 15, wherein ballast water is introduced into said gravity tank (6.2) as said first heat transfer fluid. 16. A method according to claim 15, wherein seawater is introduced into the gravity tank (6.2) as the first heat transfer fluid.

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