Air supply system for a hull of a ship and ship comprising the air supply system

Abstract

An air supply system (100) for supplying air to the exterior of a hull (201) of a marine vessel (200) is disclosed. The marine vessel comprises an engine. The air supply system comprises one or more turbochargers (10) for supplying a compressed main air flow to the engine of the marine vessel via a respective first flow path (11A). The air supply system comprises an exhaust gas recirculation (EGR) system for recirculating exhaust gas into the compressed main air flow supplied to the engine via a second flow path (11B). The air supply system comprises a third flow path (11C) for supplying a compressed air sub-flow to one or more air discharge units (ADU). The EGR system comprises a blower (31) arranged in the second flow path (11B) for supplying exhaust gas to the engine. The first and second flow paths have a first connection path (11AB) upstream of the blower (31) and a second connection path (11BA) downstream of the blower. The third flow path is fluidly connected with the first and second flow paths downstream of the blower such that the compressed air sub-flow can be extracted from the first and / or second flow paths.

Description

[0001] This disclosure relates to the field of marine propulsion. Specifically, it relates to an air supply system for supplying air to the outside of a ship's hull, and a ship including such an air supply system. More particularly, it relates to an air supply system comprising an exhaust gas recirculation system for supplying air to the outside of the hull. Technical Background

[0002] The resistance a ship experiences while navigating water consists of multiple components, with frictional resistance being the most significant. Injecting airflow into the turbulent boundary layer surrounding the ship's hull can reduce this frictional resistance. The turbulent boundary layer lies between still water and moving water close to the ship's hull.

[0003] Air lubrication of the hull can significantly reduce friction losses. Depending on the type of propulsion used, it can substantially improve the ship's efficiency. The efficiency gain depends on speed, hull shape, the ship's draft, and / or the distribution and amount of air to the ship's wetted surfaces. The ship's draft is the vertical distance from the bottom of the keel to the waterline, and the wetted surface is the total area of ​​the ship's outer surface in contact with the surrounding water.

[0004] The improvement in overall net efficiency depends on the power required to pressurize the airflow needed to reduce friction. Therefore, net propulsion efficiency depends on the power required to facilitate airflow and the given discharge pressure at the air outlet in the hull. The discharge pressure can be correlated with the water pressure exerted on the air outlet from the water surrounding the ship. Summary of the Invention

[0005] Traditional air lubrication systems typically use electric compressors to generate airflow to the outside of the vessel. However, these known electric compressors are expensive, require maintenance, and can be inefficient.

[0006] Therefore, there is a need for an air supply system for supplying air to the outside of a ship's hull that mitigates, alleviates, or resolves existing deficiencies and provides a simpler and more efficient air supply system.

[0007] An air supply system for supplying air to the exterior of a ship's hull is disclosed. The ship includes an engine, such as an internal combustion engine, such as a diesel engine, such as a two-stroke diesel engine. The engine may be the ship's main engine. The air supply system includes one or more turbochargers for supplying a compressed main air stream to the ship's engine via a respective first flow path. The air supply system includes an exhaust gas recirculation (EGR) system for recirculating exhaust gas into the compressed main air stream supplied to the engine via a second flow path. The air supply system includes a third flow path for supplying a sub-stream of compressed air to one or more air exhaust units (ADUs). The EGR system includes a blower arranged in the second flow path for supplying exhaust gas to the engine. The first and second flow paths have a first connection path upstream of the blower and a second connection path downstream of the blower for providing fluid connection between the first and second flow paths. The third flow path is fluidly connected downstream of the blower to the first and second flow paths, enabling the extraction of a sub-stream of compressed air from the first and / or second flow paths.

[0008] The advantage of the air supply system disclosed herein is that the blower of the EGR system can be used to increase the pressure of the compressed air sub-stream supplied to the ADU, thereby reducing the ship's drag in the water. By using the blower of the EGR system to increase the pressure of the compressed air stream, air can be released through the ADU even if the pressure of the compressed air from the turbocharger does not exceed the discharge pressure at the ADU. Therefore, the efficiency of the air supply system can be improved.

[0009] A vessel is disclosed, which includes an engine and an air supply system disclosed herein.

[0010] The advantage of the vessel according to this disclosure is that the blower of the EGR system can be used to increase the pressure of the compressed air sub-stream supplied to the ADU, thereby reducing the vessel's drag in the water. By using the blower of the EGR system to increase the pressure of the compressed air stream, air can be released through the ADU even if the pressure of the compressed air from the turbocharger does not exceed the discharge pressure at the ADU, such as when the vessel's engine is operating under loads below a load threshold. Therefore, the vessel's efficiency can be improved because the reduction in the vessel's drag in the water can be initiated at lower vessel speeds. Attached Figure Description

[0011] The above and other features and advantages of this disclosure will be readily apparent to those skilled in the art from the following detailed description of exemplary embodiments with reference to the accompanying drawings, in which:

[0012] Figure 1It is a graph showing scavenging pressure and draft pressure relative to the engine load of an exemplary vessel.

[0013] Figure 2 An exemplary air supply system including a single turbocharger according to this disclosure is shown.

[0014] Figure 3 An exemplary air supply system including multiple turbochargers according to this disclosure is shown, and

[0015] Figures 4 to 12 Different exemplary operating modes of the air supply system according to this disclosure are shown. Detailed Implementation

[0016] Various exemplary embodiments and details are described below with reference to the accompanying drawings (where applicable). It should be noted that the drawings may be drawn to scale or not, and that elements having similar structures or functions are indicated by the same reference numerals in all drawings. It should also be noted that the drawings are intended only to facilitate the description of embodiments. They are not intended as an exhaustive description of this disclosure or a limitation on the scope of this disclosure. Furthermore, the illustrated embodiments need not possess all the aspects or advantages shown. Aspects or advantages described in connection with a particular embodiment are not necessarily limited to that embodiment and may be practiced in any other embodiment, even if not so shown or so explicitly described.

[0017] For clarity, the accompanying drawings are schematic and simplified, and they show only details that aid in understanding this disclosure, while other details are omitted. Throughout this document, the same reference numerals are used for the same or corresponding parts.

[0018] An air supply system for supplying air to the exterior of a ship's hull is disclosed. The ship includes an engine. The air supply system uses an EGR system to recirculate exhaust gas into the combustion process in the engine to generate a compressed air flow supplied to a set of auxiliary exhaust gas detonators (ADUs). The ADUs may be configured to be disposed on the ship's hull below the waterline, such as on the wetted surface of the hull. The compressed air supplied to the ADUs may be released into the turbulent boundary layer of the water surrounding the ship to reduce drag in the water. The air supply system includes one or more turbochargers for supplying a main compressed air flow to the ship's engine via a corresponding first flow path. This main compressed air flow, also referred to as a scavenging air flow, is configured for use in the engine's combustion process. The air supply system includes an EGR system for recirculating exhaust gas, such as exhaust gas from the engine, into the main compressed air flow supplied to the engine via a second flow path. The air supply system includes a third flow path for supplying a sub-flow of compressed air to one or more ADUs. The EGR system includes a blower disposed in the second flow path for supplying exhaust gas to the engine. The blower increases the flow rate and pressure of fluid, such as exhaust gas, flowing through the second flow path. The first and second flow paths have a first connecting path upstream of the blower and a second connecting path downstream of the blower. The first and second connecting paths provide a fluid connection between the first and second flow paths. The third flow path is fluidly connected to the first and second flow paths downstream of the blower, allowing compressed air sub-streams to be drawn from the first and / or second flow paths. The fluid connection of the flow paths, such as the first, second, and third flow paths, means that the flow paths are connected, such as via the first and / or second connecting paths, allowing fluid to flow between the flow paths. The flow paths mentioned herein, such as the first, second, and third flow paths, can be multiple pipes configured to allow fluid to flow from one location to another. Connecting paths can be provided, for example, by intersecting connecting pipes or pipes containing the first and second flow paths. By connecting the first and second flow paths via a first and / or a second connection path, compressed air flow from one or more turbochargers can be diverted from the first flow path via a blower in the EGR system, where the pressure of the compressed air is increased before being supplied to the ADU via a third flow path. Therefore, the pressure of the compressed air flow can be increased to above the discharge pressure at the ADU without the need for a dedicated blower. This reduces the cost and complexity of the air supply system, thereby increasing the ship's overall net efficiency. The blower in the EGR system can be either a blower or a compressor, depending on the compression ratio required to increase the pressure of the compressed air to above the discharge pressure at the ADU.Blowers can operate at lower compression ratios than compressors, such as, for example, a compression ratio of 1.1 to 1.2 for blowers, while a compression ratio greater than 1.2 is required for compressors.

[0019] A sub-stream of compressed air can be drawn from the first flow path via the blower of the EGR system in both the first connecting path and the second flow path. This can be done, for example, when the compressed air flow in the first flow path is lower than the discharge pressure at the ADU, to increase the pressure of the compressed air using the blower of the EGR system. A sub-stream of compressed air can also be drawn from the first flow path via the second connecting path, such as without passing through the blower of the EGR system. This can be done, for example, when the compressed air flow in the first flow path is higher than the discharge pressure at the ADU, to increase the pressure of the compressed air using the blower of the EGR system. A sub-stream of compressed air can also be drawn from the second flow path via the blower of the EGR system, such as from the exhaust receiver. This can be used when further emission reduction is required, and the exhaust gas is supplied to the combustion process via the second flow path and the second connecting path 11BA.

[0020] EGR systems significantly reduce the formation of nitrogen oxides (NOx) in diesel engines. EGR systems help ships meet the International Maritime Organization (IMO) NOx Tier 3 emission limits applied in North America and the US Caribbean, as well as any new NOx Emission Control Areas (NECA). In an EGR system, after exhaust cooling and cleaning processes (such as using a scrubber), a portion of the exhaust is recirculated back to the engine, such as to the engine's scavenging air receiver. In this way, some of the oxygen in the scavenging air is replaced by carbon dioxide (CO2) from the combustion process. By replacing some of the oxygen with CO2, the O2 content is reduced, and the heat capacity of the scavenging air is increased, thereby reducing the combustion temperature peak and reducing NOx formation. The reduction in NOx is almost linear with the rate of exhaust recirculation. The IMO also has Tier 2 emission standards, which have less stringent emission limits than Tier 3 standards. The NOx emission limits for Tier 2 and Tier 3 are defined in the following: Annex VI, Article 13 of the International Convention for the Prevention of Pollution from Ships, also known as MARPOL 73 / 78. The emission limits for Tier 2 and Tier 3 apply to marine diesel engines with a power output exceeding 130 kW installed on ships.

[0021] An EGR system may include a scrubber for cleaning exhaust gas and a blower for increasing exhaust gas pressure and / or flow rate. In one or more exemplary air supply systems, the scrubber may be arranged in a second flow path. The scrubber may be arranged upstream of the blower and a first connecting path between the first and second flow paths. The scrubber may be configured to cool the exhaust gas and remove contaminants such as sulfur dioxide and particulate soot. In one or more exemplary air supply systems, the EGR system may include a cooler for cooling the exhaust gas, such as a separate cooler, and a water mist trap for removing moisture from the exhaust gas. Cooling the exhaust gas can reduce the temperature of the combustion process and increase the density of the exhaust gas, thereby improving volumetric efficiency. The water mist trap can remove moisture generated by condensation of the exhaust gas due to cooling. Removing moisture can reduce the risk of corrosion in components of the air supply system, such as flow paths or blowers.

[0022] In one or more exemplary air supply systems, the air supply system may include a first flow control device for controlling flow through a first connecting path between a first flow path and a second flow path. In one or more exemplary air supply systems, the air supply system may include a second flow control device for controlling flow through a second connecting path between the first and second flow paths. In one or more exemplary air supply systems, the air supply system may include a third flow control device for controlling flow through a third flow path. In one or more exemplary air supply systems, the air supply system may include a fourth flow control device for controlling the flow of exhaust gas entering a second flow path. Flow control devices such as the first, second, third, and / or fourth flow control devices may be orifices or control valves. Flow control devices such as the first, second, third, and / or fourth flow control devices allow compressed air flow to be directed through different flow paths depending on the operating conditions of the air supply system. By opening and closing different flow control devices, the flow paths available to the compressed flow can be adapted. The flow control devices may be controlled based on engine load, the pressure of the compressed air flow supplied by the turbocharger, the discharge pressure at the ADU, and / or the flow rate of the compressed air flow. In some exemplary air supply systems, the air supply system may include one or more sensors for monitoring engine load, pressure of the compressed air flow provided by the turbocharger, discharge pressure at the ADU, and / or flow rate of the compressed air flow.

[0023] In one or more exemplary air supply systems, the flow control device may be a fixed orifice, such as a fixed-ratio orifice, configured to passively control the flow rate through the flow path. In one or more exemplary air supply systems, a third flow control device may be an orifice, such as a fixed-ratio orifice, configured to draw a small fraction of the fluid, such as compressed air, flowing through a first flow path and / or a second flow path. The orifice may, for example, be configured to draw 0% to 20% (e.g., 6% to 10%) of the fluid flowing through the first and / or second flow paths and supply it to a third flow path to supply a sub-stream of compressed air to one or more ADUs. A fixed-ratio orifice ensures that only a predetermined amount of compressed air is drawn from the first flow path, such that sufficient compressed air is supplied to the ship's engine for engine cooling and combustion of fuel injected into the engine's combustion chamber.

[0024] In one or more exemplary air supply systems, the flow control device may be variable, such as a control valve, such as a diaphragm control valve, which can actively control the amount of gas allowed to be drawn into the air supply system.

[0025] In one or more exemplary air supply systems, the first flow control device, the second flow control device, and the fourth flow control device can be control valves. Therefore, the flow through the valves can be controlled to alter the flow path and connection route of the airflow through the air supply system.

[0026] One or more turbochargers may include: a turbine driven by an exhaust flow from an internal combustion engine, such as an exhaust flow from an engine's exhaust receiver; and a compressor for generating a compressed air flow, such as a scavenging air flow. Energy from the exhaust can therefore be used to compress the air flow.

[0027] In one or more exemplary air supply systems, the air supply system may include two or more turbochargers. The air supply system may also include one or more shut-off valves for controlling exhaust flow to at least a first turbocharger among the two or more turbochargers. One or more shut-off valves can be used to turn on or off airflow to the turbine side and / or from the compressor side of at least one of the two or more turbochargers. By closing the shut-off valve to cut off the exhaust flow to the turbine side of at least one of the turbochargers, a larger exhaust flow can be provided to the remaining turbochargers, thereby increasing the compression capacity of these turbochargers, which will increase the pressure generated by the active turbochargers. By cutting off the first turbocharger among the two or more turbochargers, all exhaust will flow through one or more second turbochargers among the multiple turbochargers, which may also be referred to as one or more active turbochargers. Since the available exhaust flow must drive a smaller number of turbochargers, the exhaust flow to each of the active turbochargers (such as an uncut turbocharger) will increase. The increased exhaust to one or more active turbochargers causes these active turbochargers to rotate faster, which increases the pressure of the compressed air from the compressor side of these turbochargers through the first flow path. Compared to the case where all turbochargers are active, the higher exhaust pressure to one or more active turbochargers increases turbocharger efficiency and thus allows higher air pressure to flow through the first flow path to the engine.

[0028] In a first exemplary operating mode of the air supply system, a first flow control device, such as a control valve, and a third flow control device, such as a control valve, can be configured to open. A second and fourth flow control devices are configured to close. Therefore, exhaust flow is prevented from passing through the second flow path, and a sub-flow of air is drawn from the first flow path and guided to the ADU via the blower of the EGR system through the first connecting path. By guiding the sub-flow of air through the first connecting path, the sub-flow of air is guided through the blower of the EGR system, where the sub-flow of air is compressed. The pressure of the sub-flow of air can thus be increased by the blower of the EGR system to a pressure higher than the discharge pressure at the ADU. Therefore, compressed air can be discharged through the ADU at lower engine loads. The increase in compressed air pressure can also be achieved without using a dedicated blower for supplying air to the ADU. Existing blowers can be used.

[0029] In a second exemplary operating mode of the air supply system, such as when the engine load is low, such as below a load threshold, one or more shut-off valves can be closed to prevent exhaust flow to at least the first turbocharger among two or more turbochargers. Consequently, the pressure of the compressed air generated by the one or more second active turbochargers in the first flow path increases. Therefore, the air supplied to the blower will also be higher, which reduces the work required for the booster to increase the pressure to above the exhaust pressure at the ADU.

[0030] In a third exemplary operating mode of the air supply system, such as when the engine load is high, such as above a load threshold, one or more shut-off valves can be opened to allow exhaust flow to at least the first turbocharger among two or more turbochargers. Therefore, when the engine is operating under higher load, a higher flow rate of compressed air can be supplied to the first flow path to supply the main compressed air flow to the engine.

[0031] In a fourth exemplary operating mode of the air supply system, such as when the ship is operating in a Level 3 NOx emission mode, the first and third flow control devices can be configured (e.g., controlled) to be off, and the second and fourth flow control devices can be configured (e.g., controlled) to be on. This allows exhaust flow to pass through the second flow path, and exhaust is supplied to the first flow path via the blower and second connection of the EGR system.

[0032] In the fifth operating mode, such as when the vessel is operating in Stage 3 NOx emission mode, the second, third, and fourth flow control devices are configured to be open, and the first flow control device is configured to be closed, so as to allow exhaust flow to pass through the second flow path and be supplied to the first and third flow paths via the blower and second connection path of the EGR system. Therefore, emissions from the combustion process can be reduced, while friction of the vessel in the water is reduced by venting air via the ADU.

[0033] A ship including an air supply system according to this disclosure is also disclosed.

[0034] Figure 1 This illustrates an example of the pressure of compressed air, such as scavenging air (Pscav), supplied to the engine by one or more turbochargers relative to engine load. The exhaust pressure at the ADU is... Figure 1 The draft pressure line is indicated in the diagram. The discharge pressure at the ADU (Automatic Duct Unit) depends on its location on the hull. When the ADU is located at the bottom of the hull, the discharge pressure corresponds to the ship's draft pressure. For air to be released to the outside of the ship's hull via the ADU, the pressure of the compressed air must overcome the discharge pressure at the ADU. Figure 1As shown, for engine loads below approximately 55%, the compressed air pressure is lower than the discharge pressure at the ADU. For applications using only those specified... Figure 1 The air supply system for the turbocharger shown in the example only releases air when the engine load is above 55%. Below, an air supply system will be disclosed that also allows air to be discharged to the outside of the vessel's hull at lower engine loads.

[0035] In the diagram below, the dashed line represents compressed air flowing through the air supply system, the black valve represents a closed valve that prevents airflow through it, and the white valve represents an open valve that allows airflow through it.

[0036] Figure 2 An exemplary air supply system 100 for supplying air to the outside of the hull 201 of a vessel 200, according to this disclosure, is shown. The vessel 200 includes an engine, such as an internal combustion engine, such as a diesel engine, such as a two-stroke diesel engine. The engine is not in... Figure 2The system is disclosed, but is indicated by an exhaust receiver for receiving exhaust gas from the engine and a scavenging air receiver for supplying scavenging air to the engine, both receivers being located on the periphery of the engine. The air supply system 100 includes a turbocharger 10 for supplying compressed main airflow, such as scavenging airflow, to the engine of the vessel 200 via a first flow path 11A. The turbocharger 10 may be driven by exhaust gas from the exhaust receiver. To prevent turbocharger overspeed, the air supply system 100 may include an exhaust bypass valve 34 for releasing exhaust gas to reduce the exhaust gas flow to the turbocharger 10. The first flow path 11A may also be referred to as the scavenging flow path. The first flow path may include: an air cooler 13 for cooling the compressed air from the turbocharger 10; a water mist trap 14 for removing moisture from the compressed air flow; and / or a check valve 15 for preventing contaminated air from the combustion process from flowing backward from the scavenging air receiver to the turbocharger 10. A water mist trap 14 may be arranged downstream of the air cooler 13 in the first flow path 11A. A check valve 15 may be arranged downstream of the water mist trap 14 in the first flow path 11A. The air supply system 100 includes an EGR system 30 for recirculating exhaust gas into the compressed main air flow of the first flow path via a second flow path 11B. The EGR system may include: a scrubber 32 for cleaning the exhaust gas; an EGR cooler 33 for cooling the exhaust gas; and a blower 31 arranged in the second flow path 11B for supplying exhaust gas to the engine, such as to a scavenging air receiver. The scrubber 32 may be arranged in the second flow path 11B upstream of the blower 31 and the first connecting path 11AB. The EGR system 30 may use the water mist trap 14 in the first flow path 11A to remove moisture from the exhaust gas. Therefore, the exhaust gas from the EGR system 30 may be guided via the water mist trap 14 in the first flow path 11A. Air supply system 100 includes a third flow path 11C for supplying a sub-stream of compressed air to one or more ADUs 20. The one or more ADUs 20 are configured to be disposed below the waterline in the hull 201 of vessel 200. First flow paths 11A and second flow paths 11B have a first connecting path 11AB upstream of blower 31 and a second connecting path 11BA downstream of blower 31. Third flow path 11C is fluidly connected to first flow paths 11A and second flow paths 11B downstream of blower 31, allowing compressed air sub-streams to be drawn from first flow paths 11A and / or second flow paths 11B. A sub-stream of compressed air can be drawn from first flow path 11A via first connecting path 11AB, second flow path 11B, and blower 31 of EGR system 30. Alternatively, a sub-stream of compressed air can be drawn from first flow path 11A via second connecting path 11AB without passing through blower 31 of EGR system 30.Compressed air sub-streams can also be drawn from the second flow path 11B via the blower 31 of the EGR system 30, such as from the exhaust receiver. In some exemplary air supply systems 100, the air supply system may include a cylinder bypass path 11D connecting the scavenging air receiver and the exhaust receiver. The air supply system may include a cylinder bypass valve 9 for controlling the airflow through the cylinder bypass path.

[0037] Cylinder bypass 11D allows excess air to bypass the combustion process. When the air supply system includes only a single turbocharger, cylinder bypass valve 9 can open under high engine loads to compensate for the reduced flow from the single turbocharger.

[0038] The air supply system 100 may include: a first flow control device 12A for controlling flow, such as opening and / or closing, through a first connecting path 11AB between a first flow path 11A and a second flow path 11B; a second flow control device 12B for controlling flow through a second connecting path 11BA between the first flow path 11A and the second flow path 11B; a third flow control device 12C for controlling flow through the third flow path 11C; and / or a fourth flow control device 12D for controlling exhaust flow into the second flow path 11B. The first, second, third, and fourth flow control devices 11A to 11D are control valves in the example shown here. However, flow control devices such as the third flow control device 12C may also be orifices with a fixed flow rate. The first flow control device 12A is arranged in the first connecting path 11AB between the first flow path 11A and the second flow path 11B. The second flow control device 12B is arranged in the second connecting path 11BA between the second flow path 11B and the first flow path 11A.

[0039] Figure 3 An exemplary air supply system 100 for supplying air to the outside of the hull 201 of a vessel 200, according to the present disclosure, is shown. Figure 3 Exemplary air supply system 100 and Figure 2The exemplary air supply system differs in that the air supply system 100 includes two or more turbochargers 10, such as a first turbocharger 10 and a second turbocharger 10A. The air supply system 100 also includes one or more shut-off valves 17 for controlling exhaust flow to at least the first turbocharger 10A among the two or more turbochargers 10, 10A. By closing the shut-off valve 17, exhaust flow to the first turbocharger 10A can be shut off. This allows a larger flow rate of exhaust to be supplied to the remaining turbochargers, such as the first turbocharger 10. By shutting off the first turbocharger among the two or more turbochargers, all exhaust will flow through the first turbocharger 10, which may also be referred to as the active turbocharger. Since the available exhaust flow must drive a smaller number of turbochargers, the exhaust flow to the first turbocharger 10 increases. Compared to a configuration where all turbochargers 10, 10A are active, the increased exhaust to the active turbocharger causes it to rotate faster, increasing the pressure of the compressed air from this turbocharger through flow path 11A. The second turbocharger 10A may have a different size than the first turbocharger 10. The second turbocharger 10A can supply compressed air to the scavenging air receiver via a dedicated flow path. Figure 3 In the exemplary air supply system 100 shown, the second turbocharger may share a flow path with the EGR system 30, such that compressed air from the second turbocharger 10A is supplied to the scavenging air receiver via the second flow path 11B. The EGR system 30 and the second turbocharger 10A can therefore share a cooler and a water mist trap 14. The air cooler 13 for the second turbocharger 10A and the EGR cooler 33 can therefore be the same cooler. The second turbocharger 10A and the EGR system 30 may not use the second flow path simultaneously. The second flow path can therefore be used by the second turbocharger 10A or by the EGR system 30. The first turbocharger 10 can therefore be used with the EGR without the second turbocharger 10A, or with the second turbocharger 10A without the EGR. The dimensions of the second turbocharger can be designed (this may also be referred to as being matched) to allow the maximum possible EGR flow through the second flow path. The engine can therefore receive an airflow including normal air from the second flow path 11B during stage 2 operation, or during stage 3 operation, it can receive clean exhaust gas with reduced O2 content from the EGR system, such as from the scrubber 32. The flow rates of the two different flows can be substantially the same, but the O2 content can be different.

[0040] Figure 4An exemplary operating mode of the air supply system disclosed herein is disclosed. In this exemplary operating mode, the air supply system operates in IMO Level 2 mode without supplying air to ADU 20. Under this operating condition, both flow control devices 12A and 12B are shut down, which... Figure 3 The valve is indicated by a black line. The compressed air flow, indicated by the dashed arrow, therefore follows the first flow path 11A, such as the scavenging flow path, from the turbocharger to the scavenging air receiver. No compressed air flow will pass through the connecting path 11AB, the connecting path 11BA, the second flow path 11B, or the third flow path 11C.

[0041] Figure 5 An exemplary operating mode of the exemplary air supply system disclosed herein is disclosed. In this exemplary operating mode, the air supply system 10 operates in IMO Level 2 mode, supplying air to ADU 20. The ship's engine can operate at a load below a load threshold, such that the pressure of the compressed air from the turbocharger 10 is insufficient to overcome the discharge pressure at ADU 20. In this operating mode, the first flow control device 12A and the third flow control device 12C are configured to be open, as indicated by the white valve in the figure. The second flow control device 12B and the fourth flow control device 12D are configured to be closed to prevent flow through the second connection path 11BA and to prevent exhaust flow through the second flow path. An air sub-stream is drawn from the first flow path 11A via the first connection path 11AB and directed via the first connection path 11AB to the blower 31 of the EGR system 30, wherein the pressure of the air sub-stream is increased by the blower to a pressure higher than the discharge pressure at ADU 20. When the pressure of the air stream has been increased by the blower to a pressure level higher than the discharge pressure at the ADU, the air stream can overcome the discharge pressure at the ADU and flow through the third flow path 11C to one or more ADUs 20 via the third flow control device 12C. The third flow control device 12C can be throttled to provide a target flow rate to the ADU 20.

[0042] Figure 6 It shows the relationship with Figure 5 The same operating mode is shown, but it is used for air supply systems 100 that include more than one turbocharger, such as Figure 3 The air supply system 100 shown. For an exemplary air supply system including more than one turbocharger, such as including a first turbocharger 10 and a second turbocharger 10A, one or more shut-off valves 17 can close when the pressure of the compressed air is lower than the discharge pressure at the ADU, as indicated by... Figure 6The black valve indicates that exhaust flow is prevented from reaching at least one of the two or more turbochargers 10, 10A. This increases exhaust flow to the remaining active turbochargers, such as those to the turbocharger 10 in the two or more turbochargers 10, 10A. The first flow control device 12A and the third flow control device 12C are configured to open, as indicated by the white valve in the figure. The second flow control device 12B and the fourth flow control device 12D are configured to close to prevent flow through the second connecting path 11BA and to prevent exhaust flow through the second flow path. An air sub-stream is drawn from the first flow path 11A via the first connecting path 11AB and directed to the blower 31 of the EGR system 30 via the second flow path 11B, wherein the pressure of the air sub-stream is increased by the blower to a pressure higher than the exhaust pressure at ADU 20. When the pressure of the air stream has been increased by the blower to a pressure level higher than the discharge pressure at the ADU, the air stream can overcome the discharge pressure at the ADU and flow through the third flow path 11C to one or more ADUs 20 via the third flow control device 12C. The third flow control device 12C can be throttled to provide a target flow rate to the ADU 20.

[0043] Figure 7 An exemplary operating mode of the exemplary air supply system disclosed herein is disclosed. In this exemplary operating mode, the air supply system 10 operates in IMO Level 2 mode, supplying air to ADU 20. The ship's engine operates at a load above a load threshold, such that the pressure of the compressed air from the turbocharger 10 is sufficient to overcome the exhaust pressure at ADU 20. The second flow control device 12B and the third flow control device 12C are configured to be open, as indicated by the white valves in the figure. The first flow control device 12A and the fourth flow control device 12D are configured to be closed to prevent flow through the first connection path 11AB and to prevent exhaust flow through the second flow path 11B. An air sub-stream is drawn from the first flow path 11A via the second connection path 11BA and directed via the second connection path 11BA to the third flow path 11C to bypass the blower 31 of the EGR system 30. Because the pressure of the compressed air sub-stream is higher than the discharge pressure at the ADU, the compressed air sub-stream flows through the third flow path 11C via the open third flow control device 12C to one or more ADUs 20 in the hull 201 of the vessel 200. By bypassing the blower, the pressure loss of the compressed air sub-stream can be reduced because the route via the second connection path 11BA has fewer restrictions than the route via the first connection path 11AB and the blower 31. The third flow control device 12C and / or the second flow control device 12B can be throttled to provide a target flow rate to the ADU 20. The same operating mode can be applied to... Figure 3An exemplary air supply system 100 includes more than one turbocharger, such as a first turbocharger 10 and a second turbocharger 10A. Therefore, a sub-stream of air is drawn from the first flow path 11A to the ADU 20 via a second connection path 11BA and supplied to the ADU 20 via a third flow path 11C.

[0044] Figure 8a It shows the relationship with Figure 7 The same operating mode is shown, but it is used for air supply systems 100 that include more than one turbocharger, such as Figure 3 The air supply system 100 shown. For an exemplary air supply system including more than one turbocharger, such as including a first turbocharger 10 and a second turbocharger 10A, one or more shut-off valves 17 can be opened, as by Figure 8a The white valve indicates that exhaust flow is allowed to reach turbocharger 10A. Shut-off valve 17 can be opened, for example, when the pressure of compressed air from the first turbocharger 10 is higher than the discharge pressure at ADU 20, or when the first turbocharger 10 has reached its maximum load limit. First flow control device 12A and third flow control device 12C are configured to open, as indicated by the white valve in the figure. Second flow control device 12B and fourth flow control device 12D are configured to close to prevent flow through the second connection path 11BA and to prevent exhaust flow through the second flow path 11B. A sub-stream of compressed air (as indicated by the white valve in the figure) is drawn from the first flow path 11A via the first connection path 11AB. Figure 8a (Indicated by the dashed line in the diagram), and guided via a second flow path 11B, in which a sub-stream of compressed air from the first turbocharger is mixed with a sub-stream of compressed air from the second turbocharger 10A. The mixed sub-stream of compressed air is drawn from the second flow path via a blower 31 of the EGR system 30, wherein the pressure of the air sub-stream can be further increased by the blower 31. If the pressure of the air sub-stream exceeds the capacity of the blower 31, the blower can rotate within the compressed air sub-stream. The mixed sub-stream of compressed air then flows through the third flow path 11C to one or more ADUs 20 via an open third flow control device 12C.

[0045] Figure 8b An additional operating mode of an exemplary air supply system 100 including more than one turbocharger is shown. When the pressure of the air sub-stream supplied by multiple turbochargers, such as the first turbocharger 10 and the second turbocharger 10A, is higher than the capacity of the blower 31, the blower can be bypassed, instead of the blower 31 rotating in the compressed air sub-stream. The first flow control device 12A and the second flow control device 12B can be activated. The compressed air sub-stream (as described by the first connection path 11AB) is drawn from the second flow path 11B via the second flow path 11B. Figure 8b (Indicated by the dashed line in the diagram), and guided via a first flow path 11A, wherein a sub-stream of compressed air from the first turbocharger 10 mixes with a sub-stream of compressed air from the second turbocharger 10A. The mixed sub-stream of compressed air is drawn from the first flow path via a second connection path 11BA, and subsequently flows through the third flow path 11C to one or more ADUs 20 via an open third flow control device 12C. This can be the case when the air supply system 100 is operating in Level 2 mode and the engine is under high load, such as at a load level above the load threshold.

[0046] Figure 9 Exemplary operating modes of the exemplary air supply system disclosed herein are presented. Figure 10 In the operating mode shown, the air supply system 10 operates in IMO Level 2 mode. The third flow control device 12C and the fourth flow control device 12D are open, while the first flow control device 12A and the second flow control device are closed. Therefore, exhaust gas can flow through the scrubber 32 and blower 31 of the EGR system 30 through the second flow path 11B to the third flow path 11C. Clean, cooled, and / or compressed exhaust gas can then be supplied to the ADU 20. Thus, when the air supply system operates in IMO Level 2 mode, the EGR system 30 can be used as an air source to supply compressed air, such as clean exhaust gas, to the ADU 20. Therefore, it is not necessary to draw air from the scavenging air flow supplied to the engine to supply air to the ADU 20, thereby increasing the amount of air available for the engine's combustion process and cooling.

[0047] Figure 10 Exemplary operating modes of the exemplary air supply system disclosed herein are presented. Figure 10In the operating mode shown, the air supply system 10 operates in IMO Level 3 mode with reduced NOx emission limits. To meet Level 3 NOx emission limits, the EGR system is activated. The fourth flow control device 12D opens, as indicated by the white valve 12D, allowing exhaust gas to flow through the scrubber 32 into the second flow path 11B. The second flow control device 12B also opens. The first flow control device 12A and the third flow control device 12C are configured to close, as indicated by the black valve in the figure. Therefore, no air is supplied to the ADU 20. Clean exhaust gas is guided to the first flow path 11A via the blower 31 of the EGR system 30 and the second connecting path 11BA, where the exhaust gas mixes with the compressed air flow from the turbocharger 10. The exhaust gas flow is thus supplied to the first flow path 11A via the blower 31 of the EGR system 30 and the second connecting path 11BA. The exhaust can be mixed with the compressed air flow upstream of the water mist trap 14, so that moisture is removed as the mixed flow passes through the water mist trap 14 before it enters the scavenging air receiver and is supplied to the engine.

[0048] Although an exemplary air supply system 100 including only one turbocharger 10 has been disclosed Figure 10 The operating mode is the same, but the same operating mode can also be used with systems containing two or more turbochargers. Figure 3 This can be used in conjunction with an exemplary air supply system. The operating mode can also be combined with turbocharger shut-off by closing the shut-off valve 17 of the second turbocharger 10A, wherein the operation of the air supply system corresponds to, for example, in... Figure 10 The disclosed air supply system 100 includes only one turbocharger 10.

[0049] Figure 11 Exemplary operating modes of the exemplary air supply system disclosed herein are presented. Figure 11In the operating mode shown, the air supply system 10 operates under NOx emission restrictions such as the more stringent IMO Level 3 mode. To meet Level 3 NOx emission restrictions, the EGR system is activated. The fourth flow control device 12D opens, as indicated by the white valve 12D, allowing exhaust gas to flow via the scrubber 32 through the second flow path 11B. The first flow control device 12A and the third flow control device 12C open, as indicated by the white valves shown. The second flow control device 12B closes. The air supply to the ADU 20 is thus active, and clean exhaust gas is directed via the blower 31 of the EGR system 30 and the second connecting path 11BA to the third flow path 11C. The first connecting path 11AB also opens, allowing clean exhaust gas to be directed via the first connecting path 11AB to the first flow path 11A, where the exhaust gas mixes with the compressed air flow from the turbocharger 10. The exhaust gas can be mixed with the compressed air flow upstream of the water mist trap 14, such that moisture is removed as the mixed flow passes through the water mist trap 14 before entering the scavenging air receiver and being supplied to the engine. To increase the airflow through the first connecting path 11AB, an additional blower 31A can be provided in the first connecting path 11AB. In some exemplary air supply systems, the blower 31 can be connected to both the first connecting path 11AB and the second connecting path 11BA. In some exemplary air supply systems 100, a dedicated blower can be provided in the first connecting path 11AB. Figure 11 In the operating mode shown, the EGR system 30 and the compressed air supply to the ADU can be active simultaneously. Therefore, NOx emissions can be reduced to meet IMO Level 3 emission limits, while further improving ship efficiency by reducing drag in the water. Figure 11 The publicly available operating model can also be applied accordingly. Figure 3 An exemplary air supply system 100 disclosed herein.

[0050] Figure 12 Exemplary operating modes of the exemplary air supply system disclosed herein are presented. Figure 12In the operating mode shown, the air supply system 10 also operates under NOx emission reduction restrictions, such as the more stringent IMO Level 3 mode. To meet Level 3 NOx emission restrictions, the EGR system is activated. The fourth flow control device 12D opens, as indicated by the white valve 12D, allowing exhaust gas to flow through the second flow path 11B via the scrubber 32. The second flow control device 12B and the third flow control device 12C open, as indicated by the white valves shown. The first flow control device 12A closes. The air supply to the ADU 20 is thus active, and clean exhaust gas is guided via the blower 31 of the EGR system 30 through the second connection path 11BA to the first flow path 11A and the third flow path 11C. A first sub-stream of clean exhaust gas is provided to the first flow path 11A, where the exhaust gas mixes with the compressed air stream from the turbocharger 10. The exhaust gas may mix with the compressed air stream upstream of the water mist trap 14, removing moisture as the mixed stream passes through the water mist trap 14 before entering the scavenging air receiver and being supplied to the engine. A second sub-stream of clean exhaust gas is provided to a third flow path 11C and further to ADU 20. The ratio of the first sub-stream to the second sub-stream is controlled using a second flow control device 12B and a third flow control device 12C. The second flow control device 12B and the third flow control device 12C can be control valves. The second flow control device 12B and the third flow control device 12C can be throttled, for example, controlled, to provide a desired flow ratio. This ratio may depend on the exhaust volume required by the combustion process in the engine to meet IMO Level 3 or Level 2 emission limits. Figure 12 In the operating mode shown, the EGR system 30 and the compressed air supply to the ADU 20 can be active simultaneously. Therefore, NOx emissions can be reduced to meet IMO Level 3 emission limits, while further improving ship efficiency by reducing drag in the water. Figure 12 The publicly available operating model can also be applied accordingly. Figure 3 An exemplary air supply system 100 disclosed herein.

[0051] It should be noted that Figures 2 to 12 The features mentioned in the embodiments described herein are not limited to these specific embodiments. Therefore, any features related to the following also apply to, as per the description of, the embodiments described herein. Figure 3 The description includes an air supply system comprising more than one turbocharger: an air supply system comprising a single turbocharger and an air supply system comprising therein and relating to Figure 2 The operating modes of components mentioned in the air supply system (such as the operation of flow control devices).

[0052] The implementation schemes of the products (air supply systems and marine vessels) disclosed herein are set forth in the following terms:

[0053] Clause 1. An air supply system (100) for supplying air to the outside of the hull (201) of a vessel (200), the vessel (200) including an engine, the air supply system (100) comprising:

[0054] - One or more turbochargers (10) for supplying compressed main airflow to the ship's engine via a corresponding first flow path (11A),

[0055] - An exhaust gas recirculation (EGR) system (30) for recirculating exhaust gas into the compressed main airflow supplied to the engine via a second flow path (11B); and

[0056] - A third flow path (11C) for supplying compressed air sub-streams to one or more air emission units (ADUs) (20), wherein one or more ADUs (20) are configured to be arranged below the waterline in the hull (201) of the vessel (200).

[0057] -The EGR system (30) includes a blower (31) arranged in the second flow path (11B) for supplying exhaust gas to the engine.

[0058] -The first flow path (11A) and the second flow path (11B) have a first connecting path (11AB) upstream of the blower (31) and a second connecting path (11BA) downstream of the blower (31) to provide fluid connection between the first flow path and the second flow path, and

[0059] -The third flow path (11C) is fluidly connected to the first flow path (11A) and the second flow path (11B) downstream of the blower (31), so that compressed air sub-streams can be drawn from the first flow path (11A) and / or the second flow path (11B).

[0060] Clause 2. The air supply system (100) according to Clause 1, the air supply system (100) includes: a first flow control device (12A) for controlling the flow through a first connecting path (11AB) between a first flow path (11A) and a second flow path (11B); a second flow control device (12B) for controlling the flow through a second connecting path (11BA) between the first flow path (11A) and the second flow path (11B); a third flow control device (12C) for controlling the flow through a third flow path (11C); and / or a fourth flow control device (12D) for controlling the exhaust flow entering the second flow path (11B).

[0061] Clause 3. An air supply system (100) according to any one of the preceding clauses, wherein the air supply system (100) comprises two or more turbochargers (10, 10A), wherein the air supply system (100) further comprises one or more shut-off valves (17) for controlling exhaust flow to at least the first turbocharger (10A) of the two or more turbochargers (10, 10A).

[0062] Clause 4. The air supply system (100) according to Clause 2, wherein in a first operating mode, the first flow control device (12A) and the third flow control device (12C) are configured to be open and the second flow control device (12B) and the fourth flow control device (12D) are configured to be closed in order to prevent exhaust flow from passing through the second flow path (11B) and to draw air sub-flow from the first flow path (11A) and guide it to the ADU (20) via the blower (31) of the EGR system (31) via the first connection path (11AB).

[0063] Clause 5. The air supply system (100) according to Clause 4, wherein in the second operating mode, one or more shut-off valves (17) are closed to prevent exhaust flow to at least the first turbocharger (10A) of the two or more turbochargers (10).

[0064] Clause 6. An air supply system (100) as described in Clause 4 or 5, wherein in a third operating mode, one or more shut-off valves (17) are opened to allow exhaust flow to at least the first turbocharger (10A) of two or more turbochargers (10).

[0065] Clause 7. An air supply system (100) according to any one of Clauses 1 to 6, wherein in a fourth operating mode, the first flow control device (12A) and the third flow control device (12C) are configured to be closed and the second flow control device (12B) and the fourth flow control device (12D) are configured to be open so as to allow exhaust flow to pass through the second flow path (11B) and be supplied to the first flow path (11A) via the blower (31) of the EGR system (30) and the second connection path (11BA).

[0066] Clause 8. An air supply system (100) according to any one of Clauses 1 to 7, wherein in a fifth operating mode, the second flow control device (12B), the third flow control device (12C), and the fourth flow control device (12D) are configured to be open, and the first flow control device (12A) is configured to be closed, so as to allow exhaust flow to pass through the second flow path (11B) and be supplied to the first flow path (11A) and the third flow path (11C) via the blower (31) of the EGR system (31) and the second connection path (11BA).

[0067] Clause 9. An air supply system (100) according to any one of the preceding clauses, wherein the EGR system (30) includes a scrubber (32) arranged in a second flow path (11B) for cleaning exhaust gas, wherein the scrubber is arranged upstream of the blower (31) and the first connection path (11AB).

[0068] Clause 10. A vessel (200) comprising an engine and an air supply system (100) according to any one of Clauses 1 to 9.

[0069] The use of terms such as "first," "second," "third," and "fourth," "primary," "secondary," and "tertiary," etc., does not imply any specific order, but is included to identify individual elements. Furthermore, the use of terms such as "first," "second," "third," and "fourth," "primary," "secondary," and "tertiary," etc., does not indicate any order or importance, but is used to distinguish one element from another. It should be noted that the terms "first," "second," "third," and "fourth," "primary," "secondary," and "tertiary," etc., used here and elsewhere, are for labelling purposes only and are not intended to indicate any specific spatial or temporal order. Moreover, the labeling of a first element does not imply the existence of a second element, and vice versa.

[0070] It should be noted that the word "including" does not necessarily exclude the presence of other elements or steps not listed.

[0071] It should be noted that the words "one" or "a kind" preceding an element do not preclude the existence of multiple such elements.

[0072] Although features have been shown and described, it should be understood that they are not intended to limit the claimed disclosure, and it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the scope of the claimed disclosure. Accordingly, the specification and drawings are to be considered illustrative rather than restrictive. The claimed disclosure is intended to cover all alternatives, modifications, and equivalents.

Claims

1. An air supply system (100) for supplying air to the outside of the hull (201) of a vessel (200), the vessel (200) including an engine, the air supply system (100) comprising: - One or more turbochargers (10) for supplying compressed main airflow to the engine of the vessel via a corresponding first flow path (11A). - Exhaust gas recirculation system (30) for recirculating exhaust gas into the compressed main air flow supplied to the engine via a second flow path (11B); as well as - A third flow path (11C) for supplying compressed air sub-streams to one or more air discharge units (20), wherein the one or more air discharge units (20) are configured to be arranged below the waterline in the hull (201) of the vessel (200). - The exhaust gas recirculation system (30) includes a blower (31) arranged in the second flow path (11B) for supplying exhaust gas to the engine. - Wherein the first flow path (11A) and the second flow path (11B) have a first connecting path (11AB) upstream of the blower (31) and a second connecting path (11BA) downstream of the blower (31), for providing fluid connection between the first flow path and the second flow path, and - wherein the third flow path (11C) is fluidly connected to the first flow path (11A) and the second flow path (11B) downstream of the blower (31), such that the compressed air sub-stream can be drawn from the first flow path (11A) and / or the second flow path (11B).

2. The air supply system (100) according to claim 1, wherein the air supply system (100) comprises: A first flow control device (12A) is used to control the flow through the first connecting path (11AB) between the first flow path (11A) and the second flow path (11B); a second flow control device (12B) is used to control the flow through the second connecting path (11BA) between the first flow path (11A) and the second flow path (11B); a third flow control device (12C) is used to control the flow through the third flow path (11C); and / or a fourth flow control device (12D) is used to control the exhaust flow entering the second flow path (11B).

3. The air supply system (100) according to claim 2, wherein in a first operating mode, the first flow control device (12A) and the third flow control device (12C) are configured to be open and the second flow control device (12B) and the fourth flow control device (12D) are configured to be closed to prevent exhaust flow from passing through the second flow path (11B) and to draw air sub-flow from the first flow path (11A) and guide it to the air emission unit (20) via the blower (31) of the exhaust recirculation system (30) via the first connecting path (11AB).

4. The air supply system (100) of claim 1, wherein the air supply system (100) comprises two or more turbochargers, and wherein the air supply system (100) further comprises one or more shut-off valves (17) for controlling the exhaust flow to at least the first turbocharger (10A) of the two or more turbochargers.

5. The air supply system (100) according to claim 4, wherein in a second operating mode, the one or more shut-off valves (17) are closed to prevent the exhaust flow from flowing to at least the first turbocharger (10A) of the two or more turbochargers.

6. The air supply system (100) according to claim 4, wherein in a third operating mode, the one or more shut-off valves (17) open to allow the exhaust flow to at least the first turbocharger (10A) of the two or more turbochargers.

7. The air supply system (100) according to claim 2, wherein in a fourth operating mode, the first flow control device (12A) and the third flow control device (12C) are configured to be closed and the second flow control device (12B) and the fourth flow control device (12D) are configured to be open to allow exhaust flow to pass through the second flow path (11B) and be supplied to the first flow path (11A) via the blower (31) of the exhaust recirculation system (30) and the second connection path (11BA).

8. The air supply system (100) according to claim 2, wherein in a fifth operating mode, the second flow control device (12B), the third flow control device (12C), and the fourth flow control device (12D) are configured to be open, and the first flow control device (12A) is configured to be closed, so as to allow exhaust flow to pass through the second flow path (11B) and be supplied to the first flow path (11A) and the third flow path (11C) via the blower (31) and the second connection path (11BA) of the exhaust recirculation system (30).

9. The air supply system (100) according to any one of claims 1-8, wherein the exhaust gas recirculation system (30) includes a scrubber (32) arranged in the second flow path (11B) for cleaning the exhaust gas, wherein the scrubber is arranged upstream of the blower (31) and the first connection path (11AB).

10. A vessel (200) comprising an engine and an air supply system (100) according to any one of claims 1 to 9.

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