阅读说明：本技术 包括用于减少源于壳体的振动的系统的船及建造所述船的方法 (Ship comprising a system for reducing vibrations originating from a hull and method of building said ship ) 是由 罗伯塔·普格内蒂 于 2021-07-05 设计创作，主要内容包括：本发明涉及一种船(1),包括至少一个壳体(20),其界定沿竖直方向跨船甲板(10)延伸的腔室(21)；安装在壳体内且包括多个集中质量部件(31、32、33、34)和多个质量沿长度分布的部件(35；36)的至少一个烟道(30)；多个支撑壳体(20)内的所述多个部件的结构(51、52、53)。所述支撑结构包括：多个主平台(51),每个主平台限定位于所述腔室(21)内的主支撑底座并通过主弹性悬架(61)的介入在船甲板(10)连接至壳体(20)的壁；及多个辅助平台(52),每个辅助平台仅由所述多个主平台(51)中的一个直接或间接地支撑,并且限定相对于由相应主平台(51)限定的主支撑底座设置在不同高度上的辅助支撑底座。(The invention relates to a vessel (1) comprising at least one hull (20) defining a chamber (21) extending in a vertical direction across a deck (10) of the vessel; at least one flue (30) mounted within the housing and comprising a plurality of lumped mass components (31, 32, 33, 34) and a plurality of components (35; 36) with masses distributed along the length; a plurality of structures (51, 52, 53) supporting the plurality of components within the housing (20). The support structure includes: a plurality of main platforms (51), each defining a main supporting base located inside said chamber (21) and connected to the walls of the hull (20) at the ship deck (10) by the interposition of main elastic suspensions (61); and a plurality of auxiliary platforms (52), each auxiliary platform being directly or indirectly supported by only one of said plurality of main platforms (51) and defining auxiliary support feet arranged at different heights with respect to the main support feet defined by the respective main platform (51).)

1. Vessel (1) comprising:

-a hull (2);

-a plurality of decks (10) provided within the hull (2);

-at least one housing (20) defining a chamber (21) extending in a vertical direction from at least one engine room (22) across the plurality of decks (10) to a chimney (23);

-at least one flue (30) for fumes produced by one or more internal combustion engines (24) located in said at least one engine room (22), said flue (30) being mounted inside said casing (20) and comprising a plurality of components (31, 32, 33, 34) with concentrated masses and a plurality of components (35; 36) with masses distributed along their length;

-a plurality of structures (51, 52, 53) adapted to support said plurality of members (31, 32, 33, 34) having concentrated masses and said plurality of members (35; 36) having masses distributed along their length within a housing (20);

characterized in that the support structure comprises:

-a plurality of main platforms (51), each main platform (51) defining a main supporting base located inside said chamber (21) and being connected to the walls of the hull (20) at the ship deck (10) by the interposition of a main elastic suspension (61); and

-a plurality of auxiliary platforms (52), each auxiliary platform (52) being directly or indirectly supported only by one of said plurality of main platforms (51) and defining auxiliary support seats arranged at different heights with respect to the main support seat defined by the respective main platform (51);

wherein at least one of the lumped mass components (31, 32, 33, 34) is positioned on each main platform (51);

and wherein an assembly consisting of a main platform (51), a respective at least one concentrated mass element (31, 32, 33, 34), possibly one or more auxiliary platforms (52) supported by said main platform, and one or more elements (35; 36) of distributed mass along the length connected to said main platform (51) and/or possibly one or more auxiliary platforms (52) constitutes a structurally independent module (50a, 50b, 50c, 50d, 50 e);

and the primary elastic suspension (61) of each primary platform (51) is dimensioned so as to reduce, with the total mass of the respective module (50a, 50b, 50c, 50d, 50e), the transmission from the respective module (50a, 50b, 50c, 50d, 50e) to the casing (20) of low-frequency vibrations generated by the engine and transmitted inside the casing (20) through the chimney (30).

2. Vessel according to claim 1, wherein the vibrations comprise vibrations at a fundamental rotational frequency of the engine and vibrations at a firing frequency of the engine, wherein preferably the fundamental rotational frequency of the engine is 7-30Hz and the firing frequency of the engine is 40-150 Hz.

3. Vessel according to claim 1 or 2, wherein at least one module (50a, 50c) comprises two or more lumped mass parts (31, 32, 33, 34); and, the two or more lumped mass components are positioned on a main platform (51) of the module.

4. Vessel according to any of the preceding claims, wherein the main platform (51) of the module (50c) comprises non-coplanar portions.

5. Vessel according to any of the preceding claims, wherein the plurality of lumped mass components of the flue comprise at least one SCR device (31).

6. Vessel according to any of the preceding claims, wherein the plurality of lumped mass components of the flue comprise at least one exhaust gas boiler (32).

7. Vessel according to any of the preceding claims, wherein the plurality of lumped mass components of the flue comprise at least one scrubber tower (33).

8. Vessel according to any of the preceding claims, wherein the plurality of lumped mass elements of the flue comprise at least one silencer (34).

9. Vessel according to any of the preceding claims, wherein the plurality of mass-distributed length-wise components of the flue comprise duct sections of a duct (35) for conveying exhaust gases.

10. Vessel according to any of the preceding claims, comprising one or more lines for the passage of a working fluid, wherein the pipe sections of the pipes (36) of the one or more lines for the passage of a working fluid are mounted within the shell (20) and are connected as additional mass distributed along the length to the support structure (51, 52, 53), wherein preferably each module (50a, 50b, 50c, 50d, 50e) comprises one or more pipe sections of the pipes (36).

11. Vessel according to any of the preceding claims, wherein the pipe sections of the pipe (35) for the passage of exhaust gases and the pipe sections of the pipe (36) of the one or more pipes for the passage of working fluid, which pipe sections are arranged in a first module, if provided, are in fluid connection with the pipe sections of the pipes of the respective pipes arranged in a second module arranged adjacent to the first module by means of a flexible connection (37).

12. Vessel according to any of the preceding claims, wherein the main elastic suspensions (61) of each main platform (51) are symmetrically distributed with respect to the centre of gravity of the respective module (50a, 50b, 50c, 50d, 50 e).

13. Vessel according to any of the preceding claims, wherein the support structure comprises a plurality of structural interconnections (53) between a main platform (51) of a module and each auxiliary platform (52) of the same module (50a, 50b, 50c, 50d, 50e), wherein the structural interconnections (53) are preferably vertical and connect the auxiliary platform (52) directly to the main platform (51) or indirectly to the main platform (51) through at least one intermediate auxiliary platform.

14. Vessel according to any of the preceding claims, wherein the auxiliary platforms (52) of the modules are arranged above and/or below the respective main platform (51).

15. Vessel according to any of the preceding claims, wherein each auxiliary platform (52) of the module consists of a structure that is thinner and lighter than the structure constituting the respective main platform (51).

16. Vessel according to any of the preceding claims, wherein in a module (50a, 50b, 50c, 50d, 50e) the sum of the mass of the respective main platform (51) and the mass of the at least one lumped mass element (31, 32, 33, 34) amounts to more than 50% of the mass of the whole module (50a, 50b, 50c, 50d, 50e), preferably 75-90% of the mass of the whole module.

17. Vessel according to any of the preceding claims, wherein the centre of gravity of the modules is located in the vicinity of the respective main platform (51).

18. Vessel according to any of the preceding claims, wherein one or more of the concentrated mass elements (31, 32, 33, 34) and/or one or more of the elements (35; 36) along the length of the mass are connected to the support structure (51, 52, 53) by means of one or more auxiliary elastic suspensions (62).

19. Boat according to any preceding claim, wherein said primary elastic suspension (61) and said secondary elastic suspension (62), if present, consist of passive elastic suspensions, preferably comprising decoupling means, preferably made of a body of elastic material, in particular rubber or silicone, metal springs, elastic means with a metal matrix, and/or air springs.

20. Vessel according to any of the claims 1-18, wherein the primary elastic suspension (61) and the secondary elastic suspension (62), if present, consist of semi-active elastic suspensions.

21. Vessel according to any of the claims 1-18, wherein the primary elastic suspension (61) and the secondary elastic suspension (62), if present, consist of active elastic suspensions.

22. Boat according to any one of the preceding claims, wherein each module (50a, 50b, 50c, 50d, 50e) is structurally independent from the others and is mechanically connected to the casing (20) only by means of the primary elastic suspension (61).

23. Vessel according to any of the preceding claims, wherein each module (50a, 50b, 50c, 50d, 50e) is a self-supporting structure, preferably prefabricated off-board.

24. Method of building a ship (1), comprising the following operating steps:

-building a hull (2) having a plurality of decks (10) and at least one hull (20), wherein the plurality of decks (10) are arranged within the hull (2), the at least one hull (20) defining a chamber (21) extending in a vertical direction from at least one engine room (22) across the plurality of decks (10) to a chimney (23);

- (b) mounting within the housing (20) at least one flue (30) for fumes produced by one or more internal combustion engines (24) arranged within the at least one engine room (22), wherein the flue (30) comprises a plurality of lumped mass components (31, 32, 33, 34) and a plurality of components (35; 36) of distributed mass along the length, supported within the housing by means of a plurality of structures (51, 52, 53);

characterized in that said supporting structure (51, 52, 53) comprises:

-a plurality of main platforms (51), each main platform (51) defining a main supporting base located inside said chamber (21) and being connected to the walls of the hull (20) at the ship deck (10) by the interposition of a main elastic suspension (61); and

-a plurality of auxiliary platforms (52), each auxiliary platform (52) being directly or indirectly supported only by one of said plurality of main platforms (51) and defining auxiliary support seats arranged at different heights with respect to the main support seat defined by the respective main platform (51);

and, in the mounting step (b), the support structure (51, 52, 53) and the components (31, 32, 33, 34; 35; 36) of the flue are brought together to form a structurally independent module (50a, 50b, 50c, 50d, 50 e);

wherein each structurally independent module comprises a main platform (51), at least one concentrated mass element (31, 32, 33, 34) located on said main platform, possibly one or more auxiliary platforms (52) supported by said main platform, and one or more elements (35; 36) of distributed mass along the length connected to said main platform (51) and/or to said possible one or more auxiliary platforms (52);

wherein the primary elastic suspension (61) of each primary platform (51) is dimensioned so as to reduce, with the total mass of the respective module (50a, 50b, 50c, 50d, 50e), the transmission from the respective module (50a, 50b, 50c, 50d, 50e) to the casing (20) of low-frequency vibrations generated by the engine and transmitted inside the casing (20) through the chimney (30).

Technical Field

The subject of the invention is a vessel comprising a system for reducing vibrations originating from the hull and a method of building said vessel.

In particular, the boat which is the subject of the invention is a cruise ship.

Background

A flue E for combustion fumes produced by the engines M of the ship N is arranged in one or more vertical chambers extending from the engine room S to the chimney F, passing through all the decks P of the ship, as shown in fig. 1. Each chamber has a generally rectangular cross-section, delimited around its edges by a closed structure C suitable for separating said chamber from the rest of the ship. The closed structure C, with the technical name "engine casing" or "shell", is structurally connected to the deck P of the ship. The shell C is an integral part of the ship structure and performs an important structural function.

In a cruise ship, the housing is integrated in the center of the ship. Thus, the housing is surrounded by other space than a separate structure or attachment as in a cargo ship. Thus, in a cruise ship, the housing wall is typically adjacent to the living area inside the ship.

Usually, the above-mentioned vertical chambers are also used for the passage of other ducts, such as ventilation ducts V (in particular for ventilating the engine room), steam lines, exhaust ducts (vent ducts), compressed air ducts, etc.

All the components installed in the vertical chamber (from the flue E to the ventilation ducts) are supported within said chamber by means of horizontal support beams T fixed to the walls of the housing at each ship deck, forming a series of grid-like platforms.

In recent years, due to the need to comply with increasingly stringent environmental standards, chimneys have been equipped with flue gas treatment equipment comprising very heavy and bulky components.

As shown in particular in fig. 2 and 3, in addition to the flue gas channel line TE, the flue currently comprises the following components (listed in sequence starting from the engine room S): a system for controlling NOx emissions (SCR, selective catalytic reduction), an exhaust gas boiler EGB for generating steam, a system SCB (or "scrubber") for controlling SOx emissions, and one or more silencers.

System for controlling NOx emissions

The new IMO Tier III regulations further limit the Emission limits of ECAs (Emission Control Areas). In this case, their goal is to reduce the amount of NOx emissions by 80%. The most common NOx reduction device in the ship industry is the two-stage SCR (selective catalytic reduction) system, which is positioned upstream of the exhaust gas boiler as the first element in the flue. In addition to being based on chemical processes, SCR also uses a gas-passing extruded honeycomb catalyst (extruded honeycomb catalyst). The catalyst constitutes a barrier through which the fumes pass freely, thus being a zone where energy is transferred from the fumes to the surrounding structures in the form of vibrations and sound.

Exhaust gas boiler

Some of the heat from the combustion gases is recovered in a tube bundle within the flue gas boiler to produce steam. The tube bundle constitutes a real barrier to the gas flow, which is necessary for the heat exchange, but generates vibrations and noise. Thus, energy is transferred to the support structure by means of the base of the exhaust gas boiler in the form of significant structural noise. Therefore, it is necessary to use a suitable elastic support to limit the transmission.

SCR and exhaust gas boilers are the heaviest elements within the housing. As an approximation, the weight range of a single SCR/flue gas boiler may be as follows, taking into account the size used: from 3.2t for a vessel with a GRT of 10,900 to 24t for a vessel with a GRT of 134,000.

Silencer with improved structure

To be able to perform their function, the silencers must also work according to the principle of pressure drop by exchange with surfaces made of absorbent material (resistive silencers) or according to the principle of reflection of sound waves trapped in specially designed chambers (reactive silencers). These pressure drops are similar in magnitude to the pressure drops in the exhaust gas boiler, and therefore these can also constitute preferred transmission points for structural noise. The weight of each silencer is between 1t and 10t, depending on its size.

System for controlling SOx emissions

In addition to the need to reduce NOx emissions to the air, new limits on SOx flue gas desulfurization are constantly being updated. In order to comply with new regulations, ship owners increasingly rely on treatment systems consisting of washing towers (called scrubers). These scrubbers are also areas that transmit vibrations to the housing, although to a much lesser extent than the exhaust gas boiler and the SCR, because the scrubbers cause a smaller pressure drop in the flue gases and are therefore in fact similar to the pipe sections of the pipeline. However, the scrub towers have a significant impact on the stability of the vessel, as they are positioned in the highest part of the hull and are much heavier than simple pipes. The average weight of the scrubber was about 20 t.

As previously mentioned, several components disposed within the housing transmit noise and vibration to the housing and, thus, to the surrounding structure. Thus, each structure within the housing that is connected to the deck is a potential carrier for transmitting noise radiated in the area surrounding the housing.

In particular, the flue components transmit low frequency vibrations generated by the internal combustion engine of the ship to the housing. These vibrations are basically constituted by vibrations at the basic rotational frequency of the engine and vibrations at the ignition frequency of the engine.

In order to limit the transmission of noise and vibrations from the components inside the casing to the casing, elastic suspensions (consisting of rubber bodies or rubberized brackets, etc.) are currently provided at the points where these components (washing towers, exhaust gas boilers, SCRs, pipelines, etc.) are attached to the supporting platforms inside the casing. These solutions are used in flue gas treatment plants and through pipelines.

However, in some cases, the use of elastic suspensions does not satisfactorily reduce vibrations, at least in the vicinity of the housing. In particular, these elastic suspensions cannot reduce low-frequency vibrations. Thus, at least in the cruise ship, the space adjoining the housing (which is often a valuable area because it is arranged in the centre of the ship) is separated from the housing by the intervention of a buffer space used, for example, as a storage room and/or a cabinet.

However, the arrangement of said damping space is not a completely satisfactory solution, since it not only does not always ensure an effective reduction of vibrations, but also takes up valuable space on the ship in valuable areas. This problem is especially true in average/small tonnage ships.

Therefore, there is a need in the ship industry, particularly in the cruise ship field, to further reduce the transmission of noise and vibration to the ship structure adjacent the hull without the intervention of a buffer space.

Disclosure of Invention

It is therefore an object of the present invention to eliminate or at least reduce the drawbacks of the prior art by providing a vessel with a system for reducing vibrations originating from the hull, so that the transmission of noise and vibrations to the structure adjoining the hull can be further reduced without the intervention of damping spaces.

Another object of the present invention is to provide a ship with a system for reducing vibrations originating from the hull that can be produced with substantially the same production costs as the traditional solutions and that is structurally easy to produce.

Brief description of the drawings

The technical characteristics of the invention according to the above mentioned object are clearly found in the content of the claims and the advantages of the invention will become more apparent from the following detailed description, given by way of non-limiting example only, with reference to the accompanying drawings, in which one or more embodiments of the invention are illustrated:

FIG. 1 is a cross-sectional view of a loose pulley corresponding to a housing to highlight a flue mounted therein;

FIG. 2 is a detail view of FIG. 1, with reference only to the housing and the flue;

FIG. 3 shows FIG. 2, in which only the equipment of the flue is depicted, the opposite lines not being depicted;

FIG. 4 is a cross-sectional view of a vessel having a system for reducing vibrations originating from the hull, the cross-section corresponding to the hull, according to an example of the invention;

FIG. 5 is a detail view of FIG. 4, only with reference to the housing and the chimney mounted therein;

FIG. 6 shows FIG. 5, in which only the lumped mass components of the stack are shown, and the distributed mass components are not shown;

FIG. 7 is a plan view of the housing shown in FIG. 5 according to section VII-VII shown therein;

FIGS. 8, 9, 10 and 11 are perspective views of a first module, a second module, a third module, and fourth and fifth modules, respectively, wherein the flue within the housing shown in FIGS. 4, 5 and 6 has been divided;

FIG. 12 shows FIG. 5, in which only the structure for supporting the lumped mass components is shown;

figure 13 shows a diagram of a vibration isolator with one degree of freedom;

fig. 14 shows the trend of the frequency ratio f/f0 with respect to the transmission rate T as the value of the damping ratio ζ changes;

figure 15 shows a diagram of a two-stage vibration isolator; and

fig. 16 is a schematic illustration of the operating range of certain types of passive suspensions based on the type of decoupling device used.

Like elements or parts of elements in the embodiments described below will be denoted by like reference numerals.

Detailed Description

The subject of the invention is a vessel and a method of building the vessel, wherein the vessel has a system for reducing vibrations originating from the hull.

In particular, the boat that is the subject of the invention may be a cruise ship.

With reference to the figures, the numeral 1 generally designates a boat according to the invention.

According to a general embodiment of the invention, as shown in fig. 4, the vessel 1 comprises:

-a hull 2;

a plurality of decks 10 provided within the hull 2;

at least one engine house 20 defining a chamber 21 extending from an engine room 22 upwards in a vertical direction across the plurality of decks 10 to a chimney 23; and

at least one flue 30 for the fumes generated by one or more internal combustion engines 24 arranged in the engine room 22.

In particular, the internal combustion engine 24 may be a diesel engine or a diesel/gas engine.

The chimney 30 is mounted within the housing 20 and includes a plurality of lumped mass components 31, 32, 33, 34 and a plurality of mass distributed along the length of the components 35, 36.

By "concentrated mass component" is meant a component of the flue 30 having a substantial mass (also relevant to the system in question) that is supported by one or more contact points on which the relative weight rests, but which are within a limited area.

In particular, the mass/volume ratio is equal to or greater than 100kg/m³May be classified as a lumped mass component.

In particular, the plurality of lumped mass components of the flue 30 comprise:

at least one SCR (Selective Catalytic Reduction) system 31, which is a Catalytic system for controlling NOx emissions; and/or

At least one exhaust gas boiler 32 for generating steam; and/or

At least one flue gas scrubber 33, which is a system for controlling SOx emissions; and/or

At least one silencer 34.

As shown in fig. 5, the flue 30 preferably includes: one or more SCR systems 31; one or more exhaust gas boilers 32 for generating steam; one or more flue gas scrubbing towers 33; and one or more silencers 34.

As an approximation, the average mass/volume ratio of the SCR may be about 220kg/m³(ii) a The average mass/volume ratio of the exhaust gas boiler may be about 650kg/m³(ii) a The average mass/volume ratio of the flue gas scrubber may be about 130kg/m³(ii) a The average mass/volume ratio of the silencer can be 100-220kg/m³In the meantime.

By "parts of mass distributed along the length" is meant parts of flue 30 of moderate mass (also relevant to the system in question) with extended longitudinal extension.

In particular, a pipe section of a pipe may be classified as a component having a mass distributed along its length. More particularly, the mass/volume ratio is less than 50kg/m³May be classified as a component having a mass distributed along its length.

In particular, the components along the length of the mass distribution are duct segments of duct 35 of stack 30 that fluidly connect the individual lumped mass components of the stack to each other, thereby forming the necessary fluid continuity from the engine exhaust to the stack.

In particular, the chamber 21 delimited by the housing 20 may be a single chamber from the engine room 22 to the chimney 23. More complex embodiments may be provided. For example, as shown in fig. 4, 5 and 6, the chamber 21 may be bifurcated at the bottom into two initial sections 21a and 21b (e.g. so as to be used for two separate engine rooms) connected upstream to a single upper section 21c extending up to the chimney 23.

The housing 20 may contain two or more different chimneys that may remain separate until the chimney or may be reconnected at a common end section.

For ease of description, reference will be made to a single flue, but no limitation to the case of a single flue is thereby intended.

The vessel 1 may advantageously comprise one or more lines for the passage of a working fluid, such as ventilation lines, exhaust lines, steam lines, and hydraulic lines.

Certain pipe sections of the pipe 36 of the one or more lines through which the working fluid passes may advantageously be mounted within the housing 20. These duct sections of duct 36 may be considered additional components distributed along the length relative to the mass of distributed mass component 35 of stack 20.

As shown in particular in fig. 5, 6 and 12, the vessel 1 also comprises a plurality of structures 51, 52 and 53 suitable for supporting a plurality of said lumped mass elements 31, 32, 33, 34 and a plurality of said elements 35, 36 of mass distributed along the length inside said hull 20.

According to the invention, the above-mentioned support structure comprises a plurality of main platforms 51, each defining a main support base located inside the chamber 21 and connected to the walls of the hull 20 at the ship's deck 10 by the interposition of a main elastic suspension 61.

Each main platform 51 is preferably constituted by a framework of beams which are structurally interconnected to each other to form a grid-like structure, as shown in particular in fig. 8, 9, 10 and 11.

According to the invention, the above-mentioned support structure also comprises a plurality of auxiliary platforms 52, each auxiliary platform 52 being directly or indirectly supported by one of said main platforms 51 and defining auxiliary support bases at different heights with respect to the main support base defined by the respective main platform 51.

As shown particularly in fig. 7, 8, 9, 10 and 11, each auxiliary platform 52 is preferably constituted by a framework of beams structurally interconnected to each other to form a grid-like structure.

The main platform 51 and the auxiliary platform 52 may have the same peripheral shape as the cross section of the housing, for example, a rectangular shape. Other embodiments may also be provided in which the platforms 51 and 52 have a different shape than the cross-section of the housing. The peripheral shape of the platforms is selected based on the need for the location of the components of the flue and such that the geometry of the platforms does not interfere with the walls of the housing.

According to the invention, at least one of said lumped mass elements 31, 32, 33, 34 of the chimney 30 is positioned on each main platform 51.

Two or more of the lumped mass components may be positioned on the main platform 51.

The structural independent modules 50a, 50b, 50c, 50d, 50e are constituted by an assembly of:

-a main platform 51;

-a respective at least one lumped mass element 31, 32, 33, 34;

one or more possible auxiliary platforms 52 supported by the main platform; and

one or more parts 35, 36 with distributed mass along the length, connected to said main platform 51 and/or to said one or more possible auxiliary platforms 52.

Advantageously, the flue 30 is thus divided into two or more structurally independent modules 50, which are arranged one after the other along the vertical extension of the casing 20.

According to the embodiment shown in the drawings, three separate chimneys 30 are mounted within the housing 20. Starting from the engine room, each flue 30 comprises, in succession, an SCR system 31, an exhaust gas boiler 32, a flue gas scrubber 33 and a silencer 34, which are joined together by a pipe section of a pipe 35. In the example shown in the drawings, three chimneys 30 share the same flue gas scrubber tower 33. The above-mentioned components of the three flues 30 are divided into five modules 50a, 50b, 50c, 50d, 50e, which are structurally independent of each other. The first module 50a comprises a scrub column 33 and three silencers 34; the second module 50b contains the exhaust gas boiler 32; the third module 50c comprises an SCR system 31 and two exhaust gas boilers 32; the fourth module 50d and the fifth module 50e (arranged on two separate parts of the housing) each contain an SCR system 31.

Preferably, each chimney 30 comprises at least one fan (not shown in the figures) at the top of the casing 20, close to the chimney 23.

More specifically, the fans may be contained within the first module 50a, supported by one or more secondary top platforms that support their weight on the primary platform of the first module 50a via an interconnecting structure. Alternatively, as shown in the figures, the fans may be arranged in another structurally independent module 50f (end or top module) intended to close the casing at the top and provided with its own main platform 51 (which is connected to the casing 20 by means of its own main elastic suspension 61) and one or more auxiliary platforms 52. In this case, the fan is considered as an auxiliary or secondary lumped mass component.

In particular, the modules 50a, 50b, 50c, 50d, 50e may extend in the vertical direction to an extent equal to the spacing between two or more ship decks. The modules 50a, 50b, 50c, 50d, 50e may have different vertical extensions. The vertical extension of a module is essentially determined by the dimensions of one or more lumped mass elements arranged within said module and the longitudinal extension of the individual tube sections of the tube arranged therein.

A module may comprise parts of a single chimney (as in the case of module 50e in the drawings) or may comprise parts of two or more different chimneys through the same casing section 20 (as in the case of modules 50a or 50d in the drawings).

According to the invention, the above-mentioned primary elastic suspension 61 of each primary platform 51 is dimensioned so as to attenuate the transmission of low-frequency vibrations, generated by the engine and transmitted by the chimney 30 inside the casing 20, from the respective module 50a, 50b, 50c, 50d, 50e to the casing 20. The primary elastic suspension 61 dampens the low frequency vibrations by taking advantage of the higher total mass of the respective modules 50a, 50b, 50c, 50d, 50 e.

Advantageously, damping vibrations reduces the annoying structural noise generated by them. "structural noise" refers to noise transmitted through the structure of a vessel generated by a source of vibration to the structure.

In particular, as shown in particular in fig. 6, each module 50a, 50b, 50c, 50d, 50e is supported in correspondence of a respective main platform 51 on a plurality of projections 25, which projections 25 project into the casing and are structurally integrated with the ship deck and/or within the casing 20. All these projections 25 are dimensioned to unload the entire weight of the entire module 50a, 50b, 50c, 50d, 50e onto the hull from which they extend and/or the deck of the vessel. On each projection 25, one of said primary elastic suspensions 61 is provided, said primary elastic suspension 61 being thus positioned between the module 50a, 50b, 50c, 50d, 50e and the respective projection 25.

Compared to the solutions of the prior art, thanks to the invention, the following two results are obtained, which cooperate to reduce/cut down the transmission of low and ultra-low frequency vibrations from the flue to the casing:

the connection points of the support structure to the housing are reduced: the flues are no longer connected to each deck of the ship, but only to the deck of the ship, which is arranged at the level of the main platform; and

the higher mass of the flue, and the masses of the support structures 51, 52, 53 distributed over several modules 50a, 50b, 50c, 50d, 50e, are grouped together to define a higher mass (with greater inertia) to be exploited to increase the attenuation of low and ultra-low frequency vibrations; this also makes it possible, inter alia, to use an elastic suspension with a high efficiency and a low frequency as the main elastic suspension.

In other words, the design of the flue and the opposing support structure as several structurally independent modules 50a-e makes it possible to utilize as a single structurally independent module 50a, 50b, 50 for purposes of reductionc. Natural frequency f of 50d, 50e system₀The higher mass involved in order to ensure that the characteristic frequency, fundamental frequency and firing frequency resulting from the engine operation fall within the maximum possible damping zone, thereby minimizing the vibrations transmitted to the ship structure.

Preferably, in order to be able to suspend a plurality of such mass-significant systems (i.e. structurally independent modules 50a, 50b, 50c, 50d, 50e each comprising equipment, pipelines, primary and secondary platforms) in view of the masses involved, the high-efficiency, low-frequency primary sprung suspensions used are those developed for large equipment as primary engines. These suspensions in fact have the required characteristics and, unlike those used in the prior art for suspending concentrated mass components, they are optimized to ensure a very low stiffness k, which results in a very low natural frequency of the elastic component (up to 4/5Hz), which, in combination with the mass m of the module, makes it possible to make the natural frequency f of the system₀Very low and decoupled from the excitation frequency (main frequency and ignition frequency), whereby the excitation frequency will be effectively reduced.

Specifically, the low frequency vibrations generated by the engine and transmitted within the housing 20 through the smoke stack 30 include:

-vibrations at a fundamental rotational frequency of the engine, the fundamental rotational frequency being a frequency related to the rotation of the drive shaft; and

-vibration at the engine firing frequency, the firing frequency being the frequency at which the engine cylinders fire.

Preferably, the basic rotational frequency of the engine is between 7-30Hz, and the ignition frequency of the engine is preferably between 40-150 Hz.

Preferably, the main elastic suspension 61 of each module 50a, 50b, 50c, 50d, 50e has a natural frequency lower than 7 Hz.

More specifically, each module 50a-e can be considered as a system with one degree of freedom that will have a natural resonant frequency that depends on the stiffness k of the primary elastic suspension 61 and the mass m of the oscillator (suspended module), as follows:

where m is the suspended mass and k is the stiffness of the resilient suspension.

To clarify this concept, it is useful to consider the transfer rate T, which represents the ratio between the force F transferred to the foundation (the structure/hull 20 of the vessel) and the force F0 (i.e. the excitation force).

The specific case considered by the present invention mainly relates to the transfer from the engine, through the suspension point, to the structure of the ship by means of SCR, exhaust gas boiler, silencer and scrubber, which obtain energy from it by interacting with the exhaust gas flow and discharge it.

According to the invention, the mass m is constituted by the whole module (concentrated mass part and distributed mass part, main platform and auxiliary platform).

It is also known that the transmissibility can be expressed according to the following equation:

wherein X is f/f₀F is the excitation frequency and C is the damping factor.

The amplitude of the system with one degree of freedom thus depends on the mass m, the stiffness k and the damping factor.

From the T equation given above, it can be seen that:

-the transmission rate T approaches 1 when X approaches 0; thus, the ratio is controlled by the stiffness k;

-the transfer rate T approaches zero when X approaches a value greater than 1; the ratio is controlled by the mass m.

FIG. 14 shows the frequency ratio f/f as a function of the value of the damping ratio ζ₀With respect to the trend of the transmittance T, where the damping ratio ζ corresponds to the C/Cc ratio, Cc is a critical damping coefficient. When ζ is<At 0, the transient response of the system is cyclic; when ζ is>At 1, the response of the system is no longer cyclic. When ζ is 0, the system is not damped. The case where ζ ═ 0 results from the equation my "+ Cy' + ky ═ y of the motion of the oscillator with one degree of freedomF (t), from which the natural undamped frequency f0 of the system with one degree of freedom is obtained, f (t) ═ C ═ 0. Typical zeta values for rubber are 0.05-0.1, while those for steel are 0.005-0.01.

Referring now to fig. 14, it can be seen that for values below resonance (f/f0 ═ 1), there is neither isolation nor amplification; near resonance (f/f0 ═ 1), there is amplification, while above 1.4X, the presence of the separation element significantly increases isolation. Thus, the presence of elasticity is effective when the frequency f0 of the system is at least 1.4 times lower than the excitation frequency.

For this reason, it is preferable to have a primary elastic suspension with a very low natural frequency (about 5Hz, k low) in order to maximize the isolation effect, taking into account the frequencies referred to above (which have a minimum value of around 7 Hz). Furthermore, as represented by the transmissibility equation T, in addition to resonance, the response is also quality controlled; thus, increasing the mass makes it possible to reduce f0 and thereby increase the f/f0 ratio, which is advantageous for isolating the system and thus reducing the transmission of vibrations to the structure of the ship.

Thanks to the invention, the transmission of low and ultra low frequency vibrations from the flue to the hull and structures of the ship adjacent to said hull can be significantly reduced without disturbing the hull and these structures adjacent to the hull.

In particular, it is no longer necessary to arrange a buffer space around the housing. In this way, the volume around the housing is freed (in the solutions of the prior art, the volume around the housing cannot be used as a valuable place due to the intensity of the vibrations originating from the housing).

Furthermore, the solution of the invention can be produced at a cost substantially similar to that of the conventional solutions. In particular, no intervention on the structure of the ship is required, only a reconfiguration of the structure inside the hull. As will be emphasized hereinafter, the separation of these structures into structurally independent modules 50a-e allows for the application of pre-fabrication methods that reduce assembly and installation costs.

As previously mentioned, the vessel 1 may comprise one or more pipelines through which the working fluid passes. Certain pipe sections of the pipe 36 for the one or more lines through which the working fluid passes may be mounted within the housing 20. These duct sections of duct 36 are considered to be additional mass-distributed length-wise components relative to the distributed mass components of stack 20. Certain pipe segments of the pipe 36 of the one or more lines through which the working fluid passes may be mounted within the housing 20.

Advantageously, certain pipe sections of the pipe 36 of said one or more lines installed inside the casing 20 for the passage of the working fluid can be connected to the above-mentioned support structures 51, 52, 53 as additional mass-distributed elements along the length. In this case, each structurally independent module 50a, 50b, 50c, 50d, 50e may comprise one or more duct sections of said duct 36.

Preferably, the line sections of the conduit 36 belonging to the ventilation line, the exhaust line, the steam channel line and the hydraulic line are connected to the support structure 51, 52, 53, whereas for safety reasons the conduit of the fire protection line is directly attached to the wall of the housing 20.

Preferably, the duct section of the duct 35 for the passage of the exhaust gases and the duct section of the duct 36 for the passage of the line or lines for the passage of the working fluid, arranged in a first module, are fluidly connected, if provided, by means of flexible connections 37, to the duct sections of the ducts of the respective lines provided in a second module adjacent to the first module. In this way, fluid continuity of the various lines may be ensured without structurally securing the different modules 50a-e to one another.

Preferably, as shown in the figures, and in particular in fig. 12, the above-mentioned support structure comprises a plurality of structural interconnections 53 between the main platform 51 of the module and each auxiliary platform 52 of the same module 50a, 50b, 50c, 50d, 50 e.

In particular, these structural interconnects 53 (which are preferably vertical) may directly connect the auxiliary platform 52 to the main platform 51 (as shown by module 50 b) or may indirectly connect the auxiliary platform 52 to the main platform 51 through at least one intermediate auxiliary platform (e.g., as shown by modules 50a and 50 c).

Advantageously, as shown in fig. 8-11, the support structures 51, 52, 53 in each module 50a, 50b, 50c, 50d, 50e form a structurally integrated support frame, in particular a cage-like support frame, within which the lumped mass components and the components of which the mass is distributed along the length are arranged.

The auxiliary platform 52 of one module may be arranged above and/or below the corresponding main platform 51.

Preferably, said auxiliary platform 52 of a module may be arranged above the main platform 51, as provided in modules 50a, 50b and 50 c. In this case, the structural interconnect 53 operates primarily under compression. However, embodiments may be provided in which one or more auxiliary platforms 52 may be disposed below the main platform 51, as provided in modules 50d and 50 e. In this case, some structural interconnects 53 may also operate under traction.

Preferably, each auxiliary platform 52 of a module consists of a structure that is thinner and lighter than the structure constituting the corresponding main platform 51.

More specifically, the main platform 51 of a module is structurally sized to support the entire weight of the respective entire module 50a, 50b, 50c, 50d, 50 e. Whereas the auxiliary platform 52 performs auxiliary structural functions and is therefore basically adapted to:

ensuring support of the pipeline (lighter; components with mass distributed along the length); and

ensuring that the equipment is accessible for maintenance purposes, travelling along the entire vertical extension of the housing.

For these reasons, the structure forming the auxiliary platform 52 can be reduced to a thinner and lighter structure compared to the solutions of the prior art, which on the contrary provides a structurally similar platform at each ship deck inside the hull.

This preferred arrangement provides a great deal of weight savings with respect to the support structure within the housing. For example, in a ship with 20 decks, assuming that the flue is divided into 4 modules, this means that the weight of about 16 decks can be reduced. Generally, the effect of the reduction on the total weight of the structure within the housing is estimated to be of the order of at least 40%.

Preferably, the sum of the masses of the respective main platform 51 and the at least one lumped mass element 31, 32, 33, 34 (or two or more lumped mass elements if present) in a module 50a, 50b, 50c, 50d, 50e constitutes more than 50% of the mass of the whole module, even more preferably 75-90% of the mass of the whole module.

Preferably, each module 50a, 50b, 50c, 50d, 50e is configured such that its center of gravity is located in the vicinity of the respective main platform 51. In other words, each module is configured such that the center of gravity is disposed as close as possible to a plane passing through the primary elastic suspension 61. This further promotes stability of the modules 50a, 50b, 50c, 50d, 50e within the housing. In this way, the vertical extension of a module can thus be increased without having to use stabilizing elements connecting the module to the housing at different heights relative to the main platform in order to dampen any vibrations on the module caused by the movements of the vessel.

Advantageously, as shown in the figures, in the case of a module 50c, the main platform 51 may extend over several planes, so as to position several lumped mass components at different heights within said module. In other words, the main platform 51 may include portions that are not coplanar with one another.

Preferably, each module 50a, 50b, 50c, 50d and 50e is structurally independent from the other modules and is mechanically connected to the casing 20 only by the above-mentioned primary elastic suspension 61.

Preferably, the primary elastic suspensions 61 of each primary platform 51 are distributed symmetrically with respect to the centre of gravity of the respective module.

According to a preferred embodiment, one or more of the above concentrated mass parts 31, 32, 33, 34 and/or one or more of the above mass distributed along the length of the parts 35, 36 may be connected to the support structure 51, 52, 53 by means of one or more auxiliary elastic suspensions 62. Preferably, as shown in particular in fig. 5 and 6, the lumped mass components 31, 32, 33, 34 are connected to the support structures 51, 52, 53 by means of one or more of said auxiliary elastic suspensions 62, while the components 35, 36 of mass distributed along the length are directly connected to the support structures 51, 52 and 53.

In operation, the action of the auxiliary elastic suspension 62 is added to the action of the main elastic suspension to further reduce the transmission of vibrations and noise from the flue 30 to the hull and the structure of the ship adjacent to the hull. A double suspension system is thus formed which can be considered similar to a two-stage isolator (two-stage isolator), as shown schematically in figure 15.

Preferably, dual suspensions are used when the efficiency of a single suspension is not adequate or when it is desired to attenuate not only a very low frequency but also another frequency. This is the case for diesel engines, for which both the main frequency and the ignition frequency are taken into account.

More specifically, as schematically shown in fig. 15, a double suspension with two degrees of freedom has in fact two natural frequencies, involving two masses m1 and m2, where m1 is an intermediate mass consisting in the present invention of the mass of the main platform plus the sum of the masses of the auxiliary platform and all the pipes rigidly connected to it (distributed mass). The mass m1 must be as large as possible in comparison to the mass m2 of the respective suspended lumped mass part; if necessary, up to 70% thereof.

In this particular case, there will therefore be two system dependent frequencies, lower f1 and higher fb, which is a combination of resonant frequencies f1 and f0, where:

f1 — the resonant frequency of mass m1, where mass m2 is considered fixed;

f 0-the resonant frequency of the system with one degree of freedom of mass m2, does not take into account mass m 1.

Describing the system with these two frequencies in combination makes it possible to calculate:

f1, which will always be < f1 or f 0;

fb, which will always be > f1 or f0,

at double frequency with respect to the higher frequency fb.

Preferably, the primary elastic suspension 61 and, if present, the secondary elastic suspension 62 are constituted by passive elastic suspensions. In particular, these passive elastic suspensions comprise decoupling components (decoupling components), preferably made of a body made of an elastic material, in particular rubber or silicone, a metal spring, an elastic component comprising a metal matrix, and/or an air spring. Fig. 16 schematically illustrates the working range of certain types of passive suspensions based on the type of decoupling device used.

According to a particular embodiment, the primary elastic suspension 61 and the secondary elastic suspension 62 (if present) can be constituted by:

-a semi-active elastic suspension constituted by a mass damper (mass damper); or

-an active elastic suspension.

In particular, an "active elastic suspension" refers to an active system (AVC) for isolating vibrations, which together with the suspension contains a feedback loop consisting of a sensor (e.g. a piezoelectric accelerometer or geophone), a controller and an actuator. The signals obtained by the extremely sensitive vibration sensor are analyzed by an electronic circuit which drives an electric actuator which immediately generates a reaction force compensating the vibrations. The active anti-vibration system is free of resonance and amplification of vibration at any frequency.

Advantageously, embodiments may be provided in which a combination of passive, semi-active and active resilient suspensions may be used in the same module.

According to a quite preferred embodiment of the invention each module 50a, 50b, 50c, 50d, 50e is a self-supporting structure, preferably prefabricated off-board. In operation, each module 50a, 50b, 50c, 50d, 50e is formed completely under the boat to then be installed within the housing from above.

The method of constructing the vessel 1 according to the invention will now be described.

For simplicity of description, the entire description of the vessel 1 will not be repeated, but reference will be made to the preceding description.

The method of the invention for building said vessel 1 comprises at least the following operative steps:

-a) building a hull 2 having a plurality of decks 10 and at least one hull 20, wherein the plurality of decks 10 are arranged inside the hull, the at least one hull 20 defining a chamber 21 extending in a vertical direction from at least one engine room 22 upwards across the plurality of decks 10 to a chimney 23;

b) installing at least one flue 30 in the housing 20 for flue gases generated by one or more internal combustion engines 24 arranged in the at least one engine room 22, wherein the flue 30 comprises a plurality of lumped mass parts 31, 32, 33, 34 and a plurality of parts 35, 36 of distributed mass along the length, which are supported in the housing by means of a plurality of structures 51, 52, 53.

According to the invention, the above-mentioned support structure 51, 52, 53 comprises:

a plurality of main platforms 51, each defining a main supporting base located inside said chamber 21 and connected to the walls of the hull 20 at the ship deck 10 by the interposition of main elastic suspensions 61; and

a plurality of auxiliary platforms 52, each supported directly or indirectly by only one of said main platforms 51 and defining an auxiliary support base, arranged at a different height with respect to the main support base defined by the respective main platform 51.

In the above-described mounting step, step b), the support structures 51, 52, 53 and the various components of the chimneys 31, 32, 33, 34 and 35 and 36 are brought together to form structurally independent modules 50a, 50b, 50c, 50d, 50 e.

Each structurally independent module comprises a main platform 51, at least one concentrated mass element 31, 32, 33, 34 positioned on said main platform, one or more possible auxiliary platforms 52 supported by said main platform, and one or more elements 35, 36 of distributed mass along the length connected to said main platform 51 and/or to said one or more possible auxiliary platforms 52.

The primary elastic suspension 61 of each primary platform 51 is dimensioned so as to reduce, with the total mass of the respective module 50a, 50b, 50c, 50d, 50e, the transmission from the respective module 50a, 50b, 50c, 50d, 50e to the casing 20 of the low-frequency vibrations generated by the engine and transmitted inside the casing 20 through the chimney 30.

According to a quite preferred embodiment of the invention each module 50a, 50b, 50c, 50d, 50e is a self-supporting structure, preferably prefabricated off-board. In operation, each module 50a, 50b, 50c, 50d, 50e is formed completely overboard to then be installed in the housing from above.

The present invention achieves many of the advantages that are presented throughout this specification.

Thanks to the invention, it is also possible to significantly reduce the transmission of low and ultra-low frequency vibrations from the flue to the hull and the structure of the ship adjacent to said hull, without disturbing the hull and the structure adjacent to the hull.

In particular, it is no longer necessary to arrange a buffer space around the housing. In this way, the volumes surrounding the housing are freed up, which, in the prior art solutions, cannot be used as valuable places (e.g. public areas, restaurants, etc.) due to the intensity of the vibrations originating from the housing and the structural noise generated thereby.

Furthermore, the solution of the invention can be implemented at a cost substantially similar to that of the conventional solutions. In particular, no intervention on the structure of the ship is required, only a reconfiguration of the structure inside the housing.

Advantageously, thanks to the invention, and in particular to the division of the support structure and the flue inside the housing into several modules, the design of the flue can thus have a greater degree of freedom, since it is less constrained by the deck of the ship.

According to a preferred embodiment, the configuration of the structures inside the hull as structurally independent modules makes it possible to reduce the weight on board the vessel and to lower the height of the centre of gravity, which is advantageous for the stability of the vessel.

Dividing the structure within the housing into structurally independent modules allows for the application of pre-fabrication methods that reduce assembly and installation costs.

The invention conceived in this way therefore achieves the set aims.

Of course, the invention, when implemented in practice, may also assume embodiments and configurations different from those described above, without thereby departing from the scope of the present invention.

Moreover, all the details may be replaced by technically equivalent elements, and any size, shape and material may be used, according to requirements.