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1. (WO2019007559) MODULE DE PASSAGE D'EAU ET PROCÉDÉ D'AGENCEMENT D'UN PASSAGE D'EAU À TRAVERS UNE COQUE D'UN NAVIRE MARIN
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A WATER LEAD-THROUGH MODULE AND METHOD OF ARRANGING A WATER LEAD-THROUGH TO A HULL OF A MARINE VESSEL

Technical field

[001 ] The present invention relates to a water lead-through module according to the preamble of claim 1. Invention relates also to method of arranging a water lead-through to a hull of a marine vessel.

Background art

[002] Scrubber units for scrubbing exhaust gas from internal combustion piston engines, have been used on marine vessels to some extent. In such scrubber the exhaust gas is led into the scrubber unit in which a scrubbing medium, such as an alkaline washing solution, is sprayed into the exhaust gas, whereby the alkaline components react with acidic components of the exhaust gas. The scrub-bing medium is sometimes supplied from a so-called process tank. The scrubbing medium absorbs SO2, heat and other components from the exhaust gas flow. Due to e.g. stricter environmental regulations so-called two-stage or multistage scrubber units have been developed. In such scrubber units, scrubbing medium is sprayed into the exhaust gas flow at two or several stages.

[003] As an example of such scrubber a document WO 2007/045721 A1 is referred to. WO 2007/045721 A1 discloses a method and an arrangement for treating the exhaust gases of a large supercharged internal combustion engine, especially a diesel engine, in a system, in which the exhaust gases from the engine are conducted to an exhaust gas scrubber to be washed and cooled at least mainly by water. The exhaust gases are cooled in the exhaust gas scrubber in order to condensate the water vapor in the exhaust gases and recover clean water and the thus recovered water is supplied to the inlet air of the engine. In the exhaust gas scrubber the cooling of the exhaust gases is accomplished in at least two stages, a washing stage and a cooling stage, which are arranged suc-cessively. WO 2007/045721 A1 suggests that in case the engine with its systems is placed on a watercraft or other structure placed in water, seawater may advantageously be used as a cooling liquid of the heat exchanger and similarly, as the wash water.

[004] WO20121 13977 A1 discloses a scrubber system for treating exhaust gas in a marine vessel with a water based solution includes a first scrubber unit and a second scrubber unit, an exhaust gas inlet in the first scrubber unit and an exhaust gas outlet in the second scrubber unit and a second conduit section connecting the first scrubber unit to the second scrubber unit, a first scrubbing medium circuit and a second scrubbing medium circuit. The first scrubber medium circuit is provided with a source of scrubbing solution having a first connection to an outside of a hull of the vessel beneath the water line of the vessel and the second scrubber medium circuit is provided with a source of scrubbing solution having a source of fresh water in the vessel.

[005] In a marine installation the scrubbing medium can be fresh water or sea water i.e. the water in which the vessel is floating. In case fresh water is used, it is typically re-circulated, so that the same water can be re-used, and a small portion of the re-circulated fresh water, called bleed-off, is diverted from the main stream, conducted to a treatment plant for cleaning, and discharged overboard. Used water is compensated by a certain amount of new topping-up fresh water. In case of sea water, all used water is typically conducted to a treatment plant, and discharged overboard, typically without any re-circulation taking place.

[006] The amount of sea water flow required for obtaining adequate scrubbing effect in a marine vessel is considerable and the water may be corrosive to some extend and therefore the discharge of the water from the vessel through its hull is problematic.

[007] An object of the invention is to provide a water lead-through module for discharging exhaust gas scrubbing water into the sea through a hull of a marine vessel in which the corrosive resistance and safe operation is considerably improved compared to the prior art solutions.

Disclosure of the Invention

[008] Objects of the invention can be met substantially as is disclosed in the independent claims and in the other claims describing more details of different embodiments of the invention.

[009] According to an embodiment of the invention a water lead-through module for discharging water into the sea through a hull of a marine vessel comprising a flow tube having a first end and a second end, wherein the flow tube is of a first grade steel and comprising

o an attachment flange part at the first end of the flow tube for at- taching a valve thereto,

o an outlet flange part at the second end of the flow tube extending radially outwards from the second end of the flow tube having an outer periphery,

a planar transition plate of a second grade steel having an outer periphery and comprising an opening defining an inner periphery of the transition plate in the plane, wherein the inner periphery of the transition plate conforms with an outer periphery of the outlet flange part, and wherein the transition plate is arranged axially flush with, and rigidly connected to, by welding, the outlet flange part of the flow tube.

[0010] According to an embodiment of the invention the first grade steel and the second grade steel are selected to that corrosion resistance of the first grade steel is higher than corrosion resistance of the second grade steel.

[001 1 ] According to an embodiment of the invention the first grade steel is of high-alloy austenitic stainless steel as defined in EN 1 .4547.

[0012] According to an embodiment of the invention the second grade steel is Grade A steel according to DNV (Det Norske Veritas) off-shore standards.

[0013] According to an embodiment of the invention the first grade steel is super duplex.

[0014] According to an embodiment of the invention the first grade steel is high-alloy austenitic stainless steel as defined in EN 1 .4547 and the second grade steel is Grade A steel according to DNV (Det Norske Veritas) off-shore standards.

[0015] According to an embodiment of the invention the first grade steel is high-alloy austenitic stainless steel as defined in EN 1 .4547 and the second grade steel is a duplex steel.

[0016] According to an embodiment of the invention a sealed housing is arranged around the flow tube extending from the wall of the flow tube to the transition plate.

[0017] According to an embodiment of the invention the flow tube comprises an intermediate flange part between the attachment flange part and the outlet flange part, wherein an annular housing is arranged around the flow tube extending between the intermediate flange part and the transition plate.

[0018] According to an embodiment of the invention the sealed housing is pro-vided with a leak detector.

[0019] According to an embodiment of the invention the outlet flange part extends radially outwards the flow tube of a distance D which is at least 50% of the diameter Dt of the flow tube.

[0020] According to an embodiment of the invention the transition plate is made of two separate steel parts rigidly joined to each other. Said two separate parts of the transition plate are made of different material both being of second grade steel. A radially inner part is welded to the outer periphery of the outlet flange part and, and the second, outer part is welded to the outer periphery of the inner part of the transition plate. The inner part can be of duplex steel, and the second part can be of Grade A steel according to Det Norske Veritas offshore standards.

[0021 ] Method of arranging a water lead-through to a hull of a marine vessel, comprising:

providing a flow tube of a first grade steel having a first end and a second end, wherein the flow tube is provided with an attachment flange part at the first end of the flow tube and an outlet flange part at the second end of the flow tube extending radially outwards from the second end of the flow tube having an outer periphery,

providing a planar transition plate of a second grade steel having an outer periphery and arranging an opening into the transition plate defining an inner periphery of the transition plate, such that the inner periphery of the transition plate conforms with an outer periphery of the outlet flange part, and

arranging the transition plate axially flush with, and rigidly connecting the transition plate by welding, to the outlet flange part of the flow tube, - providing an opening to the hull of the marine vessel conforming with the outer periphery of the transition plate and rigidly connecting the transition plate by welding, to the opening in the hull of the vessel.

[0022] The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims.

Brief Description of Drawings

[0023] In the following, the invention will be described with reference to the accompanying exemplary, schematic drawings, in which

Figure 1 illustrates a water lead-through module according to an embodiment of the invention,

Figure 2 illustrates a water lead-through module according to another embodiment of the invention and,

Figure 3 illustrates an exhaust gas scrubber in a marine vessel provided with a water lead-through module according to an embodiment of the invention.

Detailed Description of Drawings

[0024] Figure 1 depicts schematically a lead-through module 10 for discharging exhaust gas scrubbing water into the sea, through a hull 12 of a marine vessel. The water lead-through module 10 is shown in the figure 1 by means of four different views; view 1 a is a front view seen outside the hull 12, view 1 b is side view, view 1 d is a view behind, inside the hull and the view 1 c is a top view. The lead-through module 10 is specifically intended to serve as a submerged outlet for a scrubber water discharged from an exhaust gas scrubber installed in the vessel. In the following description the water lead-through module 10 is referred to as a module 10 for sake of simplicity.

[0025] The module 10 comprises a flow tube 14 having a first 14.1 end and a second end 14.2 and a longitudinal central axis 16. In order to cope with the corrosive discharge water of the exhaust gas scrubber of the vessel the flow tube is of corrosion resistant steel.

[0026] The flow tube 14 comprises an attachment flange part 18 at the first end 14.1 of the flow tube 14 for attaching a valve and a discharge channel from the scrubber to the flow tube, and an outlet flange part 20 at the second end 14.2 of the flow tube 14. The outlet flange part 20 is configured to extend radially out-wards from the second end 14.2 of the flow tube 14. The outlet flange has an outer periphery, which is advantageously circular. Generally the steel used in the tube 14 and the flange parts 18, 20 is referred to as a first grade steel.

[0027] As a preferred example of such first grade steel are high alloy austenitic steel and duplex (or austenitic-ferritic) steel. As an example of high-alloy austenitic stainless steel may be a steel defined in EN 1 .4547 having chemical composition in weight percentage C 0.01 / N 0.20 / Cr 20 / Ni 18 / Mo 6.1 / Others Cu. As an example of duplex steel may be a steel defined in EN 1 .4162 having chemical composition in weight percentage C 0.03 / N 0.22 / Cr 21.5 / Ni 1.5 / Mo 0.3 / Others 5Mn Cu.

[0028] As an indication of corrosion resistance can be used a Pitting Resistant Equivalent number PREN. The PREN-value is calculated using the following formula: PREN = 1 x %Cr + 3.3 x %Mo + 16 x %N, with an exception that stainless steels with molybdenum content≥ 1 .5% the PREN-value takes into account tung-sten [W] in the alloy and is defined with the formula: PREN = 1 %Cr + 3.3 ( %Mo + 0.5 %W ) + 16 %N. The higher the PRE-value, the more corrosion resistant the steel is. Advantageously the pitting resistance equivalent number of the first grade steel is equal or at least 40 and the pitting resistance equivalent number of the second grade steel is less than 40.

[0029] Further, the module 10 comprises a planar transition plate 22 having an outer periphery 22' and comprising an opening 23 defining an inner periphery 22" of the transition plate. The inner periphery 22" of the transition plate conforms to an outer periphery 20' of the outlet flange part 20 such that the peripheries are butting with each other. The transition plate 22 is arranged axially flush with the outlet flange part 20 and rigidly connected to, by welding, the outlet flange part 20 of the flow tube 14. The transition plate 22 is of normal steel equivalent to the steel used in the vessel's hull 12.

[0030] The module 10 can be prefabricated at a manufacturing plant to comprise the flow tube 14, the attachment flange part 18 and the outlet flange part 20 as well as the transition plate 22 welded to the outlet flange part 20. When the module is assembled into hull 12 of the vessel a hole corresponding to the periphery dimensions of the module 10 is made to the hull 12 and the module is welded to the hull at its periphery, which is the outer periphery 22' of the transition plate 22. The flow tube 14 is supported by a number of suitably arranged support brackets 24, optionally making use of stiffeners 26 attached to the hull 12.

[0031 ] Figure 2 depicts schematically a water lead-through module 10 according to another embodiment of the invention, which includes in addition to the features of the embodiment of the Figure 1 , some additional features. The water lead-through module 10 is shown in the figure as four different views; view 2a is a front view outside the hull 12, view 2b is side view, view 2d is a view behind, inside the hull and the view 2c is a top view. As is the embodiment in the Figure 1 , the lead-through module is specifically intended to serve as a submerged outlet for

a scrubber water discharged from an exhaust gas scrubber installed in the vessel. In the following description the water lead-through module 10 is referred to as a module for sake of simplicity.

[0032] The module 10 comprises a flow tube 14 having a first 14.1 end and a second end 14.2 and an attachment flange part 18 at the first end 14.1 of the flow tube 14 for attaching a valve and a discharge channel from the scrubber to the flow tube, and an outlet flange part 20 at the second end 14.2 of the flow tube 14. The outlet flange part 20 is configured to extend radially outwards from the second end 14.2 of the flow tube 14. The outlet flange has an outer periphery, which is advantageously circular.

[0033] Further, the module 10 comprises a planar transition plate 22 having an outer periphery 22' and comprising an opening 23 defining an inner periphery 22" of the transition plate. The inner periphery 22" of the transition plate conforms to an outer periphery 20' of the outlet flange part 20 such that the peripheries are butting with each other. The transition plate 22 is arranged axially flush with the outlet flange part 20 and rigidly connected to, by welding, the outlet flange part 20 of the flow tube 14.

[0034] The module further comprises a sealed housing 28 arranged annularly around the flow tube 14. The housing extends from an outer wall of the flow tube 14 between its ends, to the transition plate 22. This way the weld joint between the outlet flange part 20 and the transition plate 22 is enclosed by the housing 28. The housing can be of different form as is depicted by the conical dashed line referred by number 28', but in the Figure 2 the flow tube comprises an interme-diate flange part 21 between the attachment flange part 18 and the outlet flange part 20, wherein an annular housing 28 is arranged around the flow tube 14 extending between the intermediate flange part 21 and the transition plate 22.

[0035] As is depicted in the views 2c and 2d the sealed housing is provided with a leak detector 30. The leak detector can be realized in practise e.g. as a float level measuring device, an alarm float or a pressure sensor. In case the weld joint between the outlet flange part 20 and the transition plate 22 should fail and leak, the leak can be detected by increased pressure in the housing due to water entering the housing 28. Float sensors in turn indicates a raise of water surface in the housing.

[0036] Referring to the view 2C of the Figure 2 the outlet flange part 20 extends radially outwards from the flow tube of a distance D which is at least 50% of the diameter Dt of the flow tube.

[0037] The module 10 can be prefabricated at a manufacturing plant to comprise the flow tube 14, the attachment flange part 18 and the outlet flange part 20 as well as the transition plate 22 and the housing 28.

[0038] The water lead-through module 10 according to the invention is manufac-tured by providing a flow tube 14 of high-alloy austenitic stainless steel having a first end and a second end and a longitudinal central axis, wherein the flow tube is provided with an attachment flange part 18 at the first end of the flow tube for attaching a valve thereto and an outlet flange part 20 at the second end of the flow tube extending radially outwards from the second end of the flow tube having an outer periphery 20', providing a planar transition plate 22 having an outer periphery 22' and arranging an opening 23 into the transition plate 22 defining an inner periphery 22" of the transition plate, such that the inner periphery 22" of the transition plate conforms with an outer periphery 20' of the outlet flange part 20, and arranging the transition plate axially flush with, and rigidly connecting the transition plate 22 by welding, to the outlet flange part 20 of the flow tube 14, providing an opening to the hull 12 of the marine vessel conforming with the outer periphery 22' of the transition plate 22 and rigidly connecting the transition plate by welding, to the opening in the hull of the vessel.

[0039] When the module is assembled into hull 12 of the vessel at a dockyard, a hole corresponding to the periphery dimensions of the module 10 is made to the hull 12 and the module is welded to the hull at its periphery, which is the outer periphery 22' of the transition plate 22. The flow tube 14 is supported by a number of suitably arranged support brackets 24, optionally making use of stiffeners 26 attached to the hull 12.

[0040] Figure 3 shown schematically a marine vessel 100 with a hull 12. The vessel comprises at least one internal combustion engine 102 provided with an

exhaust gas channel 104 extending from the engine to outside the vessel 100 The vessel further comprises an exhaust gas scrubber 160 configured to clean the exhaust gas. The exhaust gas scrubber comprises sea water introduction system 108 configured to spray sea water into the exhaust gas stream. The ex-haust gas scrubber comprises scrubber water discharge system 1 10 extending from the scrubber 106 to the lead-through 10 as described in one of the figures 1 or 2 in the hull 12. The lead-through 10 is below the water surface 1 12 when the vessel is at sea.

[0041 ] It should be noted that in the figures the hull 12, the transition plate 22 and the tube 14 and its flange parts are illustrated by different line thicknesses for illustrative purpose only.

[0042] While the invention has been described herein by way of examples in connection with what are, at present, considered to be the most preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various combinations or modifications of its features, and several other applications included within the scope of the invention, as defined in the appended claims. The details mentioned in connection with any embodiment above may be used in connection with another embodiment when such combination is technically feasible.