Exhaust gas purification system and engine system

Abstract

This exhaust gas purification system comprises: a first exhaust gas purification device that removes nitrogen oxides from a first exhaust gas in a first casing to which the first exhaust gas discharged from a plurality of cylinders belonging to a first cylinder row is guided; and a second exhaust gas purification device that removes nitrogen oxides from a second exhaust gas in a second casing to which the second exhaust gas discharged from a plurality of cylinders belonging to a second cylinder row parallel to the first cylinder row is guided. Each of the first casing and the second casing is disposed such that the longitudinal direction thereof is along the cylinder row direction, and is disposed above an engine and at a position where at least a portion thereof overlaps the engine in plan view from the vertical direction.

Description

Exhaust gas purification system and engine system

[0001] This disclosure relates to an exhaust gas purification system for removing nitrogen oxides (NOx) from exhaust gas emitted from an engine, and an engine system equipped with the exhaust gas purification system. This application claims priority under Japanese Patent Application No. 2024-161295, filed with the Japan Patent Office on 18 September 2024, the contents of which are incorporated herein by reference.

[0002] A urea SCR system is known as an exhaust gas purification device for purifying nitrogen oxides (NOx) contained in exhaust gas emitted from an engine (diesel engine) (see Patent Document 1). In a urea SCR system, urea water injected into the exhaust gas is converted to isocyanuric acid by thermal decomposition due to the heat of the exhaust gas, and ammonia produced by the hydrolysis of this isocyanuric acid is used as a reducing agent. NOx is purified by chemically reacting NOx with ammonia in the presence of an SCR catalyst to reduce it to nitrogen and water.

[0003] Japanese Patent Publication No. 2017-217982

[0004] In the temperature range in which ammonia is produced from urea solution, biuret formation also progresses, and biuret may change to cyanuric acid, which can precipitate as a urea deposit mainly composed of cyanuric acid. If the weight of the precipitated urea deposit (precipitate) increases, there is a risk that it will collapse due to its own weight. In the case where the SCR device is mounted vertically, as in the invention described in Patent Document 1, the precipitated urea deposit may flow out from the SCR device to the upstream side of the exhaust flow path, collide with the turbine blades located upstream of the SCR device in the exhaust flow path, and damage the blades.

[0005] Furthermore, ships equipped with urea SCR systems require improved layout flexibility to effectively utilize the limited onboard space.

[0006] In view of the circumstances described above, at least one embodiment of the present disclosure aims to provide an exhaust gas purification system and an engine system that can suppress the outflow of precipitates generated inside the exhaust gas purification device into the exhaust flow path, and improve the layoutability of the exhaust gas purification system equipped with the exhaust gas purification device in a ship.

[0007] An exhaust gas purification system according to at least one embodiment of the present disclosure is an exhaust gas purification system provided in the exhaust passage of an engine located inside a ship's hull, for removing nitrogen oxides from exhaust gas discharged from the engine, wherein the engine comprises: a first cylinder row to which a plurality of cylinders arranged along a predetermined cylinder row direction belong; and a second cylinder row to which a plurality of cylinders arranged along the cylinder row direction belong, located at a position shifted in a direction intersecting the cylinder row direction from the first cylinder row in a plan view from the vertical direction, and the exhaust gas purification system comprises: a first casing configured to guide a first exhaust gas, which is the exhaust gas discharged from the plurality of cylinders belonging to the first cylinder row, and a first exhaust gas purification device configured to remove the nitrogen oxides from the first exhaust gas inside the first casing; and a second casing configured to guide a second exhaust gas, which is the exhaust gas discharged from the plurality of cylinders belonging to the second cylinder row, and a second exhaust gas purification device configured to remove the nitrogen oxides from the second exhaust gas inside the second casing. The first casing and the second casing are arranged such that their longitudinal direction aligns with the direction of the cylinder row, and are positioned above the engine, with at least a portion overlapping the engine in a plan view from above and in the vertical direction.

[0008] An engine system according to at least one embodiment of the present disclosure comprises: an exhaust gas purification system; an engine; a first turbine configured to be driven by the first exhaust gas flowing upstream of the first exhaust gas flow direction from the first exhaust gas purification device; a first compressor configured to compress the combustion gas led to the plurality of cylinders by power transmitted from the first turbine; a second turbine configured to be driven by the second exhaust gas flowing upstream of the second exhaust gas flow direction from the second exhaust gas purification device; and a second compressor configured to compress the combustion gas led to the plurality of cylinders by power transmitted from the second turbine, wherein the first turbine and the second turbine are arranged between the first compressor and the second compressor when viewed from one side in the cylinder row direction.

[0009] According to at least one embodiment of the present disclosure, an exhaust gas purification system and an engine system are provided that can suppress the outflow of precipitates generated inside the exhaust gas purification device into the exhaust flow path, and can improve the layoutability of the exhaust gas purification system equipped with the exhaust gas purification device in a ship.

[0010] This is a schematic diagram showing a ship equipped with an engine system according to one embodiment of this disclosure, viewed from the side. This is a schematic configuration diagram of the engine system according to one embodiment of this disclosure. This is a schematic diagram of the engine system according to one embodiment of this disclosure, viewed from the side. This is a schematic diagram of the engine system according to one embodiment of this disclosure, viewed from the side. This is a schematic diagram of the engine system according to one embodiment of this disclosure, viewed from one side in the cylinder row direction. This is a schematic diagram of the engine system according to one embodiment of this disclosure, viewed from above.

[0011] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples.

[0012] In the following explanation, when we simply refer to the upstream side, we mean the upstream side along the main direction of fluid flow in the part or region described in the directional explanation. Similarly, in the following explanation, when we simply refer to the downstream side, we mean the downstream side along the main direction of fluid flow in the part or region described in the directional explanation.

[0013] (Ship) Figure 1 is a schematic diagram showing a ship 1 equipped with an engine system 2 according to one embodiment of the present disclosure, viewed from the side. The engine system 2 is mounted on a ship 1 as shown in Figure 1. As shown in Figure 1, the ship 1 comprises a hull 11 having a shell including sides 12 and an upper deck 13, a superstructure 14 provided on the hull 11, and a chimney 15 provided on the hull 11. An engine room 16 is formed inside the hull 11. As shown in Figure 1, the longitudinal direction of the hull 11 is defined as the bow-stern direction, the front side of the hull 11 where the bow 17 is provided is the bow side, and the rear side of the hull 11 where the stern 18 is provided is the stern side.

[0014] (Engine System) As shown in Figure 1, the engine system 2 comprises an engine (for example, a diesel engine) 21 having multiple cylinders 22, a propeller 23, a propeller shaft 24, a marine gear 25, and an exhaust gas purification system 3. The engine 21 and the marine gear 25 are installed inside the engine room 16 described above. The engine 21 has a longitudinal direction along the bow-stern direction. The marine gear 25 is positioned near the engine 21, adjacent to the engine 21, and further aft than the engine 21.

[0015] The propeller shaft 24 and marine gear 25 are configured to transmit power from the engine 21 to the propeller 23. One end of the propeller shaft 24 is connected to the marine gear 25, and the other end extends toward the stern. The propeller 23 is mounted on the other end of the propeller shaft 24, which is located toward the stern. The propeller 23 is configured to provide thrust to the vessel 1 by being rotated by the power from the engine 21 transmitted via the propeller shaft 24 and marine gear 25. The marine gear 25 is configured to transmit the rotational speed of the engine 21's crankshaft to the propeller shaft 24 by changing the speed. The marine gear 25 has, for example, a gear and is configured to output torque according to the reduction ratio by reducing the rotational speed of the engine 21's power.

[0016] Figure 2 is a schematic diagram of an engine system 2 according to one embodiment of the present disclosure. The engine 21 in Figure 2 is schematically shown as viewed from above. As shown in Figure 2, the engine 21 comprises a first cylinder row 22A to which a plurality of cylinders 22 arranged along a predetermined cylinder row direction (vertical direction in Figure 2) belongs, and a second cylinder row 22B to which a plurality of cylinders 22 arranged along the cylinder row direction belongs, positioned at a location shifted from the first cylinder row 22A in a direction intersecting the cylinder row direction in a plan view from the vertical direction (in the illustrated example, the short-side direction of the engine 21 perpendicular to the cylinder row direction, the left-right direction in Figure 2). Each of the plurality of cylinders 22 has a combustion chamber (not shown) partitioned between the cylinder 22 and a piston (not shown) slidably housed inside the cylinder 22, and is configured to burn fuel in the combustion chamber. The engine 21 has general engine components such as fuel injectors for injecting unburned fuel into the combustion chamber.

[0017] In the embodiment shown in Figure 2, the engine system 2 includes an air intake section 26 for introducing combustion gas (e.g., air) to a plurality of cylinders 22 belonging to a first cylinder row 22A and a second cylinder row 22B, a first exhaust discharge section 27 for introducing first exhaust gas, which is exhaust gas discharged from a plurality of cylinders 22 belonging to a plurality of cylinders 22 belonging to a plurality of cylinders 22 belonging to a plurality of cylinder row 22A, and a second exhaust discharge section 28 for introducing second exhaust gas, which is exhaust gas discharged from a plurality of cylinders 22 belonging to a plurality of cylinder row 22B. The air intake section 26 includes an air intake main pipe 261 and a plurality of air intake branch pipes 262, one end of which is connected to a corresponding cylinder 22 among the plurality of cylinders 22 belonging to the first cylinder row 22A and the second cylinder row 22B, and the other end of which is connected to the air intake main pipe 261.

[0018] The first exhaust discharge section 27 includes a first main exhaust pipe 271 and a plurality of first exhaust branch pipes 272, one end of which is connected to a corresponding cylinder 22 among a plurality of cylinders 22 belonging to the first cylinder row 22A, and the other end of which is connected to the first main exhaust pipe 271. The second exhaust discharge section 28 includes a second main exhaust pipe 281 and a plurality of second exhaust branch pipes 282, one end of which is connected to a corresponding cylinder 22 among a plurality of cylinders 22 belonging to the second cylinder row 22B, and the other end of which is connected to the second main exhaust pipe 281.

[0019] (Exhaust Gas Purification System) As shown in Figure 2, the exhaust gas purification system 3 includes a first exhaust gas purification device 4, a second exhaust gas purification device 5, a first exhaust gas pipe 6, and a second exhaust gas pipe 7. The first exhaust gas purification device 4 includes a first casing 41 configured to guide first exhaust gas, which is exhaust gas discharged from a plurality of cylinders 22 belonging to the first cylinder row 22A, and is configured to remove nitrogen oxides from the first exhaust gas inside the first casing 41. The second exhaust gas purification device 5 includes a second casing 51 configured to guide second exhaust gas, which is exhaust gas discharged from a plurality of cylinders 22 belonging to the second cylinder row 22B, and is configured to remove nitrogen oxides from the second exhaust gas inside the second casing 51.

[0020] (First turbocharger, second turbocharger) In the embodiment shown in Figure 2, the engine system 2 includes a first turbocharger 8 and a second turbocharger 9. As shown in Figure 2, the first turbocharger 8 includes a first turbine 81, a first compressor 82, and a first rotating shaft 83. The first turbine 81 is located downstream of the first exhaust main pipe 271 in the flow direction of the first exhaust gas and upstream of the first exhaust gas purification device 4 in the flow direction of the first exhaust gas, and is configured to be driven (rotated) by the first exhaust gas flowing upstream of the first exhaust gas purification device 4 in the flow direction of the first exhaust gas.

[0021] The first rotating shaft 83 mechanically connects the first turbine 81 and the first compressor 82, and is configured to transmit power (rotational force) generated by the rotation of the first turbine 81 to the first compressor 82. The first compressor 82 is installed in the first air intake passage for guiding combustion gas to the air intake section 26, and is configured to compress the combustion gas flowing through the first air intake passage by power transmitted from the first turbine 81 via the first rotating shaft 83.

[0022] The engine system 2 includes a first air cleaner 84 located upstream of the first compressor 82 in the flow direction of the combustion gas in the first intake passage. The first air cleaner 84 removes impurities such as dust and dirt contained in the combustion gas introduced to the first compressor 82.

[0023] As shown in Figure 2, the second turbocharger 9 includes a second turbine 91, a second compressor 92, and a second rotating shaft 93. The second turbine 91 is located downstream of the second exhaust main pipe 281 in the flow direction of the second exhaust gas and upstream of the second exhaust gas purification device 5 in the flow direction of the second exhaust gas, and is configured to be driven (rotated) by the second exhaust gas flowing upstream of the second exhaust gas purification device 5 in the flow direction of the second exhaust gas.

[0024] The second rotating shaft 93 mechanically connects the second turbine 91 and the second compressor 92, and is configured to transmit power (rotational force) generated by the rotation of the second turbine 91 to the second compressor 92. The second compressor 92 is installed in the second air intake passage for guiding combustion gas to the air intake section 26, and is configured to compress the combustion gas flowing through the second air intake passage by power transmitted from the second turbine 91 via the second rotating shaft 93.

[0025] The engine system 2 includes a second air cleaner 94 located upstream of the second compressor 92 in the direction of combustion gas flow in the second intake air passage. The second air cleaner 94 removes impurities such as dust and dirt contained in the combustion gas introduced to the second compressor 92.

[0026] The first exhaust pipe 6 forms a passage for guiding the first exhaust gas from multiple cylinders 22 belonging to the first cylinder row 22A to the first casing 41. The first exhaust gas discharged from multiple cylinders 22 belonging to the first cylinder row 22A is guided into the first casing 41 via the first exhaust pipe 6. After nitrogen oxides are removed from the first exhaust gas by the first exhaust gas purification device 4, the first exhaust gas is discharged to the outside of the ship 1 from the chimney 15 described above. In the embodiment shown in Figure 2, the first exhaust pipe 6 includes a pipe 6A connecting the exhaust outlet of the first exhaust main pipe 271 to the exhaust inlet of the first turbine 81, and a pipe 6B connecting the exhaust outlet of the first turbine 81 to the exhaust inlet 45 of the first casing 41.

[0027] The second exhaust pipe 7 forms a passage for guiding the second exhaust gas from multiple cylinders 22 belonging to the second cylinder row 22B to the second casing 51. The second exhaust pipe 7 is designed not to merge with the first exhaust pipe 6. The second exhaust gas discharged from multiple cylinders 22 belonging to the second cylinder row 22B is guided into the second casing 51 via the second exhaust pipe 7. After nitrogen oxides are removed from the second exhaust gas by the second exhaust gas purification device 5, the second exhaust gas is discharged to the outside of the ship 1 from the chimney 15 described above. In the embodiment shown in Figure 2, the second exhaust pipe 7 includes a pipe 7A connecting the exhaust outlet of the second main exhaust pipe 281 to the exhaust inlet of the second turbine 91, and a pipe 7B connecting the exhaust outlet of the second turbine 91 to the exhaust inlet 55 of the second casing 51.

[0028] (First exhaust gas purification device, second exhaust gas purification device) Figure 3 is a schematic diagram of an engine system 2 according to one embodiment of the present disclosure, viewed from the side. Figure 3 shows a cross-section along the longitudinal direction of the first exhaust gas purification device 4. In the embodiment shown in Figure 3, the first exhaust gas purification device 4 comprises a first catalyst unit 42 and a first reducing agent addition device 43. The first catalyst unit 42 is housed in a first casing 41 and includes a selective reduction catalyst 421 for selectively reducing nitrogen oxides. The first reducing agent addition device 43 is configured to add a reducing agent within the first casing 41 to the first exhaust gas flowing upstream of the first catalyst unit 42 in the flow direction of the first exhaust gas.

[0029] Figure 4 is a schematic diagram of an engine system 2 according to one embodiment of the present disclosure, viewed from the side (opposite side from Figure 3). Figure 4 shows a cross-section along the longitudinal direction of the second exhaust gas purification device 5. In the embodiment shown in Figure 4, the second exhaust gas purification device 5 comprises a second catalyst unit 52 and a second reducing agent addition device 53. The second catalyst unit 52 is housed in a second casing 51 and includes a selective reduction catalyst 521 for selectively reducing nitrogen oxides. The second reducing agent addition device 53 is configured to add a reducing agent within the second casing 51 to the second exhaust gas flowing upstream of the second catalyst unit 52 in the flow direction of the second exhaust gas.

[0030] In the embodiments shown in FIGS. 3 and 4, the first exhaust gas purifying device 4 and the second exhaust gas purifying device 5 are SCR devices (selective catalytic reduction denitration devices) that use aqueous urea as a reducing agent. The above-described selective reduction catalysts 421 and 521 are urea water adsorption type SCR catalysts that convert aqueous urea to ammonia on the catalyst and reduce nitrogen oxides.

[0031] The first exhaust gas purifying device 4 and the second exhaust gas purifying device 5 use ammonia (ammonia gas) generated by hydrolysis of the aqueous urea injected into the exhaust gas by the heat of the exhaust gas as a reducing agent, and in the presence of an SCR catalyst, chemically react NOx with ammonia to reduce it to nitrogen and water, thereby purifying NOx. Here, the ammonia generated from the aqueous urea adsorbs to the SCR catalyst and reacts with NOx by the action of the SCR catalyst to purify NOx.

[0032] The chemical reaction in which aqueous urea purifies NOx is typically represented by the following chemical reaction formulas (1) to (3). 4NO + 4NH ３ + O ２ → 4N ２ + 6H ２ O... Formula (1) 2NO ２ + 4NH ３ → 3N ２ + 6H ２ O... Formula (2) NO + NO ２ + 2NH ３ → 2N ２ + 3H ２ O... Formula (3)

[0033] In the embodiments shown in FIGS. 3 and 4, the first reducing agent adding device 43 includes a first injection nozzle 44 configured to spray (add) a reducing agent into the first exhaust gas flowing upstream of the first catalyst part 42 in the flow direction of the first exhaust gas within the first casing 41, a reducing agent tank (not shown) for storing the reducing agent, and a reducing agent supply path (not shown) for sending the reducing agent from the reducing agent tank to the first injection nozzle 44. The reducing agent stored in the reducing agent tank can be sprayed into the first exhaust gas upstream of the first catalyst part 42 in the flow direction of the first exhaust gas within the first casing 41 via the reducing agent supply path and the first injection nozzle 44.

[0034] The first casing 41 is formed in a cylindrical shape with a longitudinal direction, and the first exhaust gas flows from one side to the other in the longitudinal direction through an internal space partitioned by its inner surface. The first casing 41 has an exhaust inlet 45 at one end in the longitudinal direction for introducing the first exhaust gas into the interior, and an exhaust outlet 46 at the other end in the longitudinal direction for discharging the first exhaust gas to the outside. In the embodiment shown in Figure 3, the exhaust inlet 45 and the exhaust outlet 46 are each formed above the center of the height of the first casing 41, making it difficult for precipitates deposited inside the first casing 41 to flow out of the first casing 41 through the exhaust inlet 45 and the exhaust outlet 46.

[0035] The second reducing agent addition device 53 includes a second injection nozzle 54 configured to spray (add) a reducing agent within the second casing 51 to the second exhaust gas flowing upstream of the second catalyst unit 52 in the flow direction of the second exhaust gas, a reducing agent tank (not shown) for storing the reducing agent, and a reducing agent supply passage (not shown) for sending the reducing agent from the reducing agent tank to the second injection nozzle 54. The reducing agent stored in the reducing agent tank can be sprayed into the second exhaust gas flowing upstream of the second catalyst unit 52 in the flow direction of the second exhaust gas within the second casing 51 via the reducing agent supply passage and the second injection nozzle 54. The first reducing agent addition device 43 and the second reducing agent addition device 53 may share a reducing agent tank.

[0036] The second casing 51 is formed in a cylindrical shape with a longitudinal direction, and the second exhaust gas flows from one side to the other in the longitudinal direction through an internal space partitioned by its inner surface. The second casing 51 has an exhaust inlet 55 at one end in the longitudinal direction for introducing the second exhaust gas into the interior, and an exhaust outlet 56 at the other end in the longitudinal direction for discharging the second exhaust gas to the outside. In the embodiment shown in Figure 4, the exhaust inlet 55 and the exhaust outlet 56 are each formed above the center of the height of the second casing 51, making it difficult for precipitates deposited inside the second casing 51 to flow out of the second casing 51 through the exhaust inlet 55 and the exhaust outlet 56.

[0037] FIG. 5 is a schematic view of the engine system 2 according to an embodiment of the present disclosure, viewed from one side in the cylinder bank direction (in the illustrated example, the side where the marine gear 25 is located with respect to the engine 21). FIG. 6 is a schematic view of the engine system 2 according to an embodiment of the present disclosure, viewed from above. As shown in FIGS. 2 to 6, the exhaust gas purification system 3 according to some embodiments includes a first casing 41 into which first exhaust gas discharged from a plurality of cylinders 22 belonging to the first cylinder bank 22A is introduced, and the above-described first exhaust gas purification device 4 configured to remove nitrogen oxides from the first exhaust gas inside the first casing 41, and a second casing 51 into which second exhaust gas discharged from a plurality of cylinders 22 belonging to the second cylinder bank 22B is introduced, and a second exhaust gas purification device 5 configured to remove nitrogen oxides from the second exhaust gas inside the second casing 51. Each of the above-described first casing 41 and second casing 51 is arranged such that its longitudinal direction is along the cylinder bank direction, and is arranged at a position above the engine 21 and at least partially overlapping the engine 21 in a plan view from the vertical direction.

[0038] In the illustrated embodiment, the engine 21 is placed on the floor surface 161 of the engine room 16. The first casing 41 and the second casing 51 are supported by a gantry 164 placed on the floor surface 163 of a partition wall 162 that vertically partitions the engine room 16 above the engine 21 in a state where the longitudinal direction is along the horizontal direction.

[0039] By limiting the purification target of the first exhaust gas purification device 4 to the first exhaust gas, and the purification target of the second exhaust gas purification device 5 to the second exhaust gas, the first exhaust gas purification device 4 and the second exhaust gas purification device 5 can be made smaller and distributed compared to an exhaust gas purification device that purifies both the first and second exhaust gases. This improves the layoutability of the first exhaust gas purification device 4 and the second exhaust gas purification device 5 on the ship 1. By arranging the first exhaust gas purification device 4 and the second exhaust gas purification device 5 directly above the engine 21, where dead space tends to occur, and with their respective longitudinal directions aligned with the cylinder row direction, the engine system 2, which includes the engine 21 and the exhaust gas purification system 3, can be made more compact, and the onboard space can be used more effectively.

[0040] By arranging the first exhaust gas purification device 4 and the second exhaust gas purification device 5 so that their respective longitudinal directions align with the cylinder row direction, any precipitates formed inside the first exhaust gas purification device 4 and the second exhaust gas purification device 5 will remain inside the devices even if they fall. This prevents precipitates formed inside the first exhaust gas purification device 4 and the second exhaust gas purification device 5 from flowing out into the exhaust passage (for example, piping 6B and 7B). Furthermore, by limiting the purification target of the first exhaust gas purification device 4 to the first exhaust gas and the purification target of the second exhaust gas purification device 5 to the second exhaust gas, the amount of precipitates formed inside the first exhaust gas purification device 4 and the second exhaust gas purification device 5 can be reduced compared to an exhaust gas purification device that purifies both the first and second exhaust gases. In this case, even if precipitates do flow out into the exhaust passage, the risk of damage to equipment such as turbines 81 and 91 installed in the exhaust passage can be reduced.

[0041] The first injection nozzle 44 is configured to spray (add) the reducing agent along a direction intersecting (orthogonal) to the longitudinal direction of the first casing 41. As shown in FIG. 3, the first injection nozzle 44 is preferably attached to the upper part of the first casing 41 and configured to spray (add) the reducing agent downward along the vertical direction. At this time, deposits accumulate below the first injection nozzle 44. By forming a viewing window that allows visual inspection of the inside of the first casing 41 at a position below the first injection nozzle 44 of the first casing 41 and shifted in the circumferential direction of the first casing 41 with respect to the first injection nozzle 44, the deposition state of the deposits in the first casing 41 can be visually recognized.

[0042] The second injection nozzle 54 is configured to spray (add) the reducing agent along a direction intersecting (orthogonal) to the longitudinal direction of the second casing 51. As shown in FIG. 4, the second injection nozzle 54 is preferably attached to the upper part of the second casing 51 and configured to spray (add) the reducing agent downward along the vertical direction. At this time, deposits accumulate below the second injection nozzle 54. By forming a viewing window that allows visual inspection of the inside of the second casing 51 at a position below the second injection nozzle 54 of the second casing 51 and shifted in the circumferential direction of the second casing 51 with respect to the second injection nozzle 54, the deposition state of the deposits in the second casing 51 can be visually recognized.

[0043] In the exhaust gas purification system 3 according to some embodiments, as shown in FIG. 6, the above-described second cylinder bank 22B is provided on one side (the first side, the right side in FIG. 6) in the intersecting direction (the lateral direction of the engine 21, the left-right direction in FIG. 6) intersecting the cylinder bank direction with respect to the first cylinder bank 22A in a plan view from the vertical direction. The above-described first casing 41 is arranged on the above-described one side (the first side, the right side in FIG. 6) in the above-described intersecting direction with respect to the second casing 51 in a plan view from the vertical direction.

[0044] In the embodiment shown in Figure 6, the first casing 41 is positioned such that at least a portion of it overlaps the second cylinder row 22B in a plan view from the top and bottom. The second casing 51 is positioned such that at least a portion of it overlaps the first cylinder row 22A in a plan view from the top and bottom.

[0045] By reversing the positional relationship between the first casing 41 and the second casing 51 in the intersecting direction compared to the positional relationship between the first cylinder row 22A, which the first casing 41 corresponds to, and the second cylinder row 22B, which the second casing 51 corresponds to, it is possible to suppress the occurrence of sharp bends in the first exhaust gas pipe 6 connecting the first casing 41 and the first cylinder row 22A, and the second exhaust gas pipe 7 connecting the second casing 51 and the second cylinder row 22B. This suppresses pressure loss in the first exhaust gas pipe 6 and the second exhaust gas pipe 7, and suppresses the decrease in exhaust gas flow velocity associated with this pressure loss, thereby allowing relatively high-temperature exhaust gas to be introduced into the first casing 41 and the second casing 51. Introducing relatively high-temperature exhaust gas into the first casing 41 and the second casing 51 suppresses the generation of precipitates, and allows the precipitates to be converted into reducing agents by heat. Here, cyanuric acid, the main component of urea deposits (precipitates), changes into ammonia, a reducing agent, due to the heat of the exhaust gas when exposed to relatively high-temperature exhaust gas.

[0046] In some other embodiments, the positional relationship between the first casing 41 and the second casing 51 in the aforementioned intersection direction may be the same as the positional relationship between the first cylinder row 22A and the second cylinder row 22B. In this case, the first casing 41 is positioned on the other side (second side, left side in Figure 6) of the second casing 51 in the aforementioned intersection direction when viewed from above or below.

[0047] In some embodiments of the exhaust gas purification system 3, as shown in Figure 5, the second exhaust gas pipe 7 (piping 7B) described above is configured to intersect the first exhaust gas pipe 6 (piping 6B) when viewed from one side in the direction of the cylinder row.

[0048] In the illustrated embodiment, the piping 6B described above is composed of a first upper piping section 6C, a first central piping section 6D, and a first lower piping section 6E. The first central piping section 6D is a straight pipe extending in a straight line along the vertical direction. One end of the first upper piping section 6C is connected to the upper end of the first central piping section 6D, and the other end is connected to the exhaust inlet 45 of the first casing 41. One end of the first lower piping section 6E is connected to the lower end of the first central piping section 6D, and the other end is connected to the exhaust outlet of the first turbine 81. The first upper piping section 6C and the first lower piping section 6E are curved in at least a portion. In the embodiment shown in Figure 5, the exhaust outlet of the first turbine 81 opens outward in the short-side direction of the engine 21 (first side, right side in Figure 5). The first upper piping section 6C and the first lower piping section 6E, when viewed from one side in the cylinder row direction, are inclined in the direction of the short side of the engine 21 (first side, right side in Figure 5) as they move upwards, at least in part.

[0049] In the illustrated embodiment, the piping 7B described above is composed of a second upper piping section 7C, a second central piping section 7D, and a second lower piping section 7E. The second central piping section 7D is a straight pipe extending in a straight line along the vertical direction. One end of the second upper piping section 7C is connected to the upper end of the second central piping section 7D, and the other end is connected to the exhaust inlet 55 of the second casing 51. One end of the second lower piping section 7E is connected to the lower end of the second central piping section 7D, and the other end is connected to the exhaust outlet of the second turbine 91. The second upper piping section 7C and the second lower piping section 7E are curved in at least a portion. In the embodiment shown in Figure 5, the exhaust outlet of the second turbine 91 opens outward in the short-side direction of the engine 21 (second side, left side in Figure 5). The second upper piping section 7C and the second lower piping section 7E, when viewed from one side in the cylinder row direction, are inclined in the direction of the short side of the engine 21 (second side, left side in Figure 5) as they move upwards, at least in part.

[0050] In the illustrated embodiment, the second lower piping section 7E is configured to intersect the first lower piping section 6E when viewed from one side in the direction of the cylinder row.

[0051] According to the above configuration, by having the second exhaust pipe 7 intersect with the first exhaust pipe 6, it is possible to suppress the occurrence of sharp bends in the first exhaust pipe 6 and the second exhaust pipe 7, and consequently, to suppress pressure loss in the first exhaust pipe 6 and the second exhaust pipe 7.

[0052] In some embodiments of the exhaust gas purification system 3, as shown in Figure 6, the first exhaust gas pipe 6 (pipe 6B) described above includes the first upper piping section 6C described above, which extends from one end connected to the first casing 41, and the second exhaust gas pipe 7 (pipe 7B) includes the second upper piping section 7C described above, which extends from one end connected to the second casing 51. The first upper piping section 6C and the second upper piping section 7C are configured such that, in a plan view from the top and bottom, the distance between them (the distance in the short-side direction of the engine 21) increases as they move toward the end connected to the casings 41 and 51 (the other side in the cylinder row direction, the upper side in Figure 6).

[0053] In this case, the first casing 41 and the second casing 51 can be separated in the short direction of the engine 21. Separating the first casing 41 and the second casing 51 makes it easier for workers to access the first exhaust gas purification device 4 and the second exhaust gas purification device 5, enabling efficient and rapid maintenance work on the first exhaust gas purification device 4 and the second exhaust gas purification device 5.

[0054] In some embodiments of the engine system 2, as shown in Figure 5, the first turbine 81 and the second turbine 91 described above are arranged between the first compressor 82 and the second compressor 92 when viewed from one side in the cylinder row direction. In the illustrated embodiment, as shown in Figure 6, the first compressor 82, the first turbine 81, the second turbine 91, and the second compressor 92 are arranged in a line along the short side of the engine 21.

[0055] In this case, the necessary length can be secured in the intersecting direction (the short side of the engine 21) that crosses the cylinder row direction for the exhaust gas pipe (piping 6B) connecting the first turbine 81 and the first casing 41, and the exhaust gas pipe (piping 7B) connecting the second turbine 91 and the second casing 51, thereby suppressing the occurrence of sharp bends in these exhaust gas pipes.

[0056] In some embodiments of the engine system 2, as shown in Figure 6, the first turbocharger 8 and the second turbocharger 9 described above are positioned above the marine gear 25, and at least a portion of them overlap the marine gear 25 in a plan view from the vertical direction.

[0057] In this case, by positioning the first turbocharger 8 and the second turbocharger 9 directly above the marine gear 25, where dead space is likely to occur, the engine system 2 can be made more compact, and the space inside the ship can be used effectively.

[0058] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.

[0059] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0060] The contents described in some of the embodiments above can be understood, for example, as follows:

[0061] 1) An exhaust gas purification system (3) according to at least one embodiment of the present disclosure is an exhaust gas purification system (3) provided in the exhaust passage of an engine (21) provided inside the hull for removing nitrogen oxides from exhaust gas discharged from the engine (21), wherein the engine (21) comprises a first cylinder row (22A) to which a plurality of cylinders (22) arranged along a predetermined cylinder row direction belong, and a second cylinder row (22B) to which a plurality of cylinders arranged along the cylinder row direction belong, located at a position shifted in a direction intersecting the cylinder row direction from the first cylinder row in a plan view from the vertical direction, and the exhaust gas purification system (3) includes a first casing (41) configured to guide a first exhaust gas, which is the exhaust gas discharged from the plurality of cylinders (22) belonging to the first cylinder row (22A), and a first exhaust gas purification device (4) configured to remove the nitrogen oxides from the first exhaust gas inside the first casing (41), The engine comprises a second casing (51) configured to guide a second exhaust gas, which is the exhaust gas discharged from the plurality of cylinders (22) belonging to the second cylinder row (22B), and a second exhaust gas purification device (5) configured to remove nitrogen oxides from the second exhaust gas inside the second casing (51), wherein the first casing (41) and the second casing (51) are arranged such that their longitudinal direction is aligned with the direction of the cylinder row, and are positioned above the engine (21) and at least a portion of them overlap the engine (21) in a plan view from the top and bottom.

[0062] According to the configuration described in 1) above, by limiting the purification target of the first exhaust gas purification device (4) to the first exhaust gas and the purification target of the second exhaust gas purification device (5) to the second exhaust gas, the first exhaust gas purification device (4) and the second exhaust gas purification device (5) can be made smaller and distributed compared to an exhaust gas purification device that purifies both the first and second exhaust gases. This improves the layoutability of the first exhaust gas purification device (4) and the second exhaust gas purification device (5) on the ship (1). By arranging the first exhaust gas purification device (4) and the second exhaust gas purification device (5) directly above the engine (21), where dead space tends to occur, and with their respective longitudinal directions aligned with the cylinder row direction, the engine system (2) equipped with the engine (21) and exhaust gas purification system (3) can be made more compact, and the onboard space can be used effectively.

[0063] According to the configuration described in 1) above, by arranging the first exhaust gas purification device (4) and the second exhaust gas purification device (5) so that their respective longitudinal directions are aligned with the cylinder row direction, any precipitates generated inside the first exhaust gas purification device (4) and the second exhaust gas purification device (5) will remain inside the devices even if they fall. Therefore, it is possible to suppress the outflow of precipitates generated inside the first exhaust gas purification device (4) and the second exhaust gas purification device (5) into the exhaust flow path. Furthermore, by limiting the purification target of the first exhaust gas purification device (4) to the first exhaust gas and the purification target of the second exhaust gas purification device (5) to the second exhaust gas, the amount of precipitates generated inside the first exhaust gas purification device (4) and the second exhaust gas purification device (5) can be reduced compared to an exhaust gas purification device that purifies both the first and second exhaust gases. In this case, even if precipitates do flow into the exhaust flow path, the risk of damage to equipment such as turbines installed in the exhaust flow path can be reduced.

[0064] 2) In some embodiments, the exhaust gas purification system (3) described in 1) above, wherein the second cylinder row (22B) is provided on one side in the intersecting direction that intersects the cylinder row direction with respect to the first cylinder row (22A) in a plan view from the vertical direction, and the first casing (41) is positioned on the one side in the intersecting direction with respect to the second casing (51) in a plan view from the vertical direction.

[0065] According to the configuration described in 2) above, by reversing the positional relationship between the first casing (41) and the second casing (51) in the intersecting direction compared to the positional relationship between the first cylinder row (22A) corresponding to the first casing (41) and the second cylinder row (22B) corresponding to the second casing (51), it is possible to suppress the occurrence of sharp bends in the first exhaust gas pipe (6) connecting the first casing (41) and the first cylinder row (22A), and the second exhaust gas pipe (7) connecting the second casing (51) and the second cylinder row (22B). As a result, pressure loss in the first exhaust gas pipe (6) and the second exhaust gas pipe (7) can be suppressed, and the decrease in exhaust gas flow velocity associated with this pressure loss can be suppressed, thereby allowing relatively high-temperature exhaust gas to be guided to the first casing (41) and the second casing (51). By introducing relatively high-temperature exhaust gas into the first casing (41) and the second casing (51), the formation of precipitates can be suppressed, and the precipitates can be converted into reducing agents by heat.

[0066] 3) In some embodiments, the exhaust gas purification system (3) described in 2) above further comprises: a first exhaust gas pipe (6) for guiding the first exhaust gas from the plurality of cylinders (22) belonging to the first cylinder row (22A) to the first casing (41); and a second exhaust gas pipe (7) for guiding the second exhaust gas from the plurality of cylinders (22) belonging to the second cylinder row (22B) to the second casing (51), the second exhaust gas pipe (7) being configured to intersect the first exhaust gas pipe (6) when viewed from one side in the direction of the cylinder row.

[0067] According to the configuration described in 3) above, by crossing the second exhaust pipe (7) with respect to the first exhaust pipe (6), it is possible to suppress the occurrence of sharp bends in the first exhaust pipe (6) and the second exhaust pipe (7), and consequently, to suppress pressure loss in the first exhaust pipe (6) and the second exhaust pipe (7).

[0068] 4) In some embodiments, the exhaust gas purification system (3) described in 3) above, wherein the first exhaust gas pipe (6) includes a first upper piping section (6C) extending from one end connected to the first casing (41), and the second exhaust gas pipe (7) includes a second upper piping section (7C) extending from one end connected to the second casing (51), and the first upper piping section (6C) and the second upper piping section (7C) are configured such that, in a plan view from the vertical direction, the distance between them increases as they move toward the one end.

[0069] According to the configuration described in 4) above, the first casing (41) and the second casing (51) can be separated. Separating the first casing (41) and the second casing (51) makes it easier for workers to access the first exhaust gas purification device (4) and the second exhaust gas purification device (5), enabling efficient and rapid maintenance work on the first exhaust gas purification device (4) and the second exhaust gas purification device (5).

[0070] 5) An engine system (2) according to at least one embodiment of the present disclosure comprises: an exhaust gas purification system (3) according to any one of 2) to 4) above; an engine (21); a first turbine (81) configured to be driven by the first exhaust gas flowing upstream of the first exhaust gas flow direction of the first exhaust gas purification device (4); a first compressor (82) configured to compress the combustion gas led to the plurality of cylinders (22) by power transmitted from the first turbine (81); a second turbine (91) configured to be driven by the second exhaust gas flowing upstream of the second exhaust gas flow direction of the second exhaust gas purification device (5); and a second compressor (92) configured to compress the combustion gas led to the plurality of cylinders (22) by power transmitted from the second turbine (91), The first turbine (81) and the second turbine (91) are positioned between the first compressor (82) and the second compressor (92) when viewed from one side in the direction of the cylinder row.

[0071] According to the configuration in 5) above, the necessary length in the intersecting direction that crosses the cylinder row direction can be secured for the exhaust gas pipe connecting the first turbine (81) and the first casing (41), and the exhaust gas pipe connecting the second turbine (91) and the second casing (51), and the occurrence of sharp bends in these exhaust gas pipes can be suppressed.

[0072] 1. Ship 2. Engine system 3. Exhaust gas purification system 4. First exhaust gas purification device 5. Second exhaust gas purification device 6. First exhaust pipe 7. Second exhaust pipe 8. First turbocharger 9. Second turbocharger 21. Engine 25. Marine gear 41. First casing 51. Second casing 81. First turbine 82. First compressor 91. Second turbine 92. Second compressor

Claims

1. An exhaust gas purification system provided in the exhaust passage of an engine located inside the hull of a ship, for removing nitrogen oxides from exhaust gas discharged from the engine, wherein the engine comprises: a first cylinder row to which a plurality of cylinders arranged along a predetermined cylinder row direction belong; and a second cylinder row to which a plurality of cylinders arranged along the cylinder row direction belong, located at a position shifted in a direction intersecting the cylinder row direction from the first cylinder row in a plan view from the vertical direction, and the exhaust gas purification system comprises: a first casing configured to guide a first exhaust gas, which is the exhaust gas discharged from the plurality of cylinders belonging to the first cylinder row, and a first exhaust gas purification device configured to remove the nitrogen oxides from the first exhaust gas inside the first casing; and a second casing configured to guide a second exhaust gas, which is the exhaust gas discharged from the plurality of cylinders belonging to the second cylinder row, and a second exhaust gas purification device configured to remove the nitrogen oxides from the second exhaust gas inside the second casing. An exhaust gas purification system wherein the first casing and the second casing are arranged such that their longitudinal directions are aligned with the direction of the cylinder row, and are positioned above the engine and overlapping the engine in a plan view from the vertical direction, at least a portion of them.

2. The exhaust gas purification system according to claim 1, wherein the second cylinder row is provided on one side in the intersecting direction that intersects the cylinder row direction with respect to the first cylinder row in a plan view from the vertical direction, and the first casing is positioned on the one side in the intersecting direction with respect to the second casing in a plan view from the vertical direction.

3. The exhaust gas purification system according to claim 2, further comprising: a first exhaust gas pipe for guiding the first exhaust gas from the plurality of cylinders belonging to the first cylinder row to the first casing; and a second exhaust gas pipe for guiding the second exhaust gas from the plurality of cylinders belonging to the second cylinder row to the second casing, the second exhaust gas pipe configured to intersect the first exhaust gas pipe when viewed from one side in the direction of the cylinder row.

4. The exhaust gas purification system according to claim 3, wherein the first exhaust gas pipe includes a first upper piping section extending from one end connected to the first casing, and the second exhaust gas pipe includes a second upper piping section extending from one end connected to the second casing, and the first upper piping section and the second upper piping section are configured such that, in a plan view from the vertical direction, the distance between them increases as they approach the one end.

5. An engine system comprising: an exhaust gas purification system according to any one of claims 2 to 4; the engine; a first turbine configured to be driven by the first exhaust gas flowing upstream of the first exhaust gas flow direction from the first exhaust gas purification device; a first compressor configured to compress the combustion gas led to the plurality of cylinders by power transmitted from the first turbine; a second turbine configured to be driven by the second exhaust gas flowing upstream of the second exhaust gas flow direction from the second exhaust gas purification device; and a second compressor configured to compress the combustion gas led to the plurality of cylinders by power transmitted from the second turbine, wherein the first turbine and the second turbine are arranged between the first compressor and the second compressor when viewed from one side in the cylinder row direction.

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