KR20190064658A - EGR systems and diesel engines - Google Patents

Abstract

In the EGR system and the diesel engine, damage to the blades of the compressor of the turbocharger is suppressed. A scrubber for cleaning the recycle gas which is a part of the exhaust gas discharged from the expander by the liquid, a demister for removing the droplets contained in the recycle gas washed by the scrubber, And an EGR blower disposed downstream of the recirculating gas flow, and a silencer having one end in the direction of the axis of rotation connected to the compressor and the other end in the direction of the axis of rotation connected to the EGR blower, As shown in Fig.

Description

EGR systems and diesel engines

The present invention relates to an EGR system and a diesel engine.

The exhaust gas discharged from the diesel engine contains harmful substances such as NOx, SOx, and sold out. Particularly, in a marine diesel engine in which a low quality fuel is used, the amount of harmful substances contained in the exhaust gas also increases. Therefore, a marine diesel engine needs a technique for treating the harmful substances and an exhaust gas treatment device in order to cope with various exhaust gas regulations.

As a method for reducing NOx in the exhaust gas, there is exhaust gas recirculation (EGR). In this EGR, a part of the exhaust gas (recirculating gas) exhausted from the combustion chamber of the diesel engine is mixed with the combustion air to be used as combustion gas and returned to the combustion chamber. Therefore, the combustion gas has a lowered oxygen concentration, and the burning temperature is lowered by slowing the rate of combustion, which is the reaction between the fuel and oxygen, and the amount of NOx generated can be reduced.

As described above, the exhaust gas discharged from the diesel engine contains harmful SOx and dust, which is harmful to the engine. Therefore, a part of the exhaust gas, which is the recirculating gas, passes through the EGR valve and is subjected to SOx, Is removed. Thereafter, the recirculating gas is mixed with the combustion air sucked from the atmosphere and returned to the diesel engine as the combustion gas. At this time, the scrubber removes harmful substances by injecting liquid to the recirculating gas which is a part of the exhaust gas. Here, when the recycle gas passes through the scrubber, droplets are contained in the recycle gas after passing through the scrubber. In order to remove droplets, a mist separator is mounted downstream of the scrubber in the flow direction of the recirculating gas (Patent Document 1).

Here, the EGR system including the scrubber and the mist separator is mounted on the diesel engine main body in order to secure the space of the engine room. In this case, the EGR system is mounted so as to increase the efficiency of the diesel engine. For example, in a diesel engine, a supercharger is mounted to improve performance. As described in Patent Document 2 and Patent Document 3, the engine performance deteriorates when the temperature of the combustion air sucked into the supercharger is high. The recirculation gas passage in the exhaust gas passage and the EGR system is arranged to be spaced apart from the intake port of the combustion air of the supercharger so as not to raise the atmosphere temperature of the intake port of the combustion air of the supercharger (refer to Non-Patent Document 1 ).

Japanese Laid-Open Patent Publication No. 2016-168574 Japanese Utility Model Publication No. 55-176437 Japanese Patent Publication No. 6008495 Japanese Laid-Open Patent Publication No. 2014-163345

 PROJECT MEET NEWS April 7, 2015

However, even when the mist separator is mounted as in Patent Document 1, there is a possibility that droplets are still contained in the recycle gas. In a diesel engine, a supercharger is mounted to improve the performance. When the recirculating gas containing the droplet passes through the compressor constituting the turbocharger, the droplet may mechanically deform or shave the surface of the vane of the compressor. . Further, in the case where the S (sulfur) component is contained in the droplet of the recirculating gas, scientific corrosion (corona) may occur on the wing surface of the compressor due to the droplet containing the S component (Patent Document 4). Further, even when coating is carried out on the wax surface of the compressor, in the case where the liquid droplet is large, there is a fear that the coating is peeled off, resulting in erosion and corona transition.

Also, it has been newly found that, as in the non-patent document 1, the possibility of condensation of the saturated water in the recirculating gas increases by increasing the distance from the mist separator (demister) and the EGR blower to the supercharger in preference to the engine performance. Even in this case, there is a fear that the wing car of the supercharger is subjected to erosion and corona transition, and the wing car may be damaged.

An object of the present invention is to provide an EGR system and a diesel engine that suppress damage to a bladed wheel of a compressor of a supercharger.

According to an aspect of the present invention, there is provided an EGR system including a supercharger having an expander and a compressor connected to each other by a rotary shaft, a scrubber for cleaning a recycle gas, which is a part of exhaust gas discharged from the expander, with a liquid, A demister for removing droplets contained in the recirculating gas; an EGR blower disposed downstream of the recycle gas flow of the demister; and one end of the EGR blower connected to the compressor in the direction of the axis of rotation, And the other end of the EGR blower is connected to the EGR blower, and the EGR blower is disposed on the other end side of the silencer in the direction of the rotation axis.

Therefore, the recycle gas from which the droplet has been removed by the demister is sucked into the EGR blower, and then sent to the compressor via the silencer. Here, when the EGR blower is disposed on the other end side of the silencer, the passage length can be shortened while reducing the curvature of the passage between the silencer and the EGR blower. Even after the droplet is removed by the demister, the moisture of the recirculating gas is in a saturated state, so droplets may occur if the passage of the recirculating gas is long. On the other hand, in the EGR system, since the EGR blower is disposed on the other end side of the silencer, the passage length can be shortened while reducing the bent portion of the passage (piping) between the silencer and the EGR blower, The condensation of water in the recirculating gas can be suppressed until this. As a result, the EGR system can suppress the occurrence of aging and corona discharge. The EGR system is capable of suppressing the occurrence of oil mist and corona discharge, thereby suppressing the damage to the wing car and making the life of the wing car lighter.

The EGR system of the present invention is characterized in that the demister is disposed on the other end side of the silencer.

Therefore, in the EGR system, since the demister is located at the other end of the silencer, the passage length can be shortened, as well as the passage between the EGR blower and the silencer as well as the bend of the passage between the demister and the silencer. Even after the droplet is removed by the demister, the moisture of the recirculating gas is saturated, so that a droplet may occur if the passage of the recirculating gas is long, but the EGR system reduces the bend of the passage between the silencer and the demister The length of the passage can be shortened, so that the condensation of water in the recirculating gas can be further suppressed until it reaches the compressor. As a result, the EGR system can suppress the occurrence of aging and corona discharge. As a result, the EGR system can suppress damage to the wing car and increase the life span of the wing car.

The EGR system of the present invention is characterized in that the scrubber is mounted on the demister and is disposed on the side of the EGR blower rather than the other end of the silencer.

Therefore, since the scrubber is mounted on the upper portion of the demister, the recycle gas containing the drainage and droplets generated from the scrubber is directly introduced into the demister from the scrubber. Here, since the waste liquid used in the scrubber contains a large amount of S component, it is necessary to manage the apparatus constituting the EGR system so that corrosion does not occur. The EGR system is managed by making the distance between the scrubber and the demister the shortest distance The score of the device can be minimized. Therefore, the burden of the maintenance can be greatly reduced in the EGR system.

The EGR system of the present invention is characterized in that the silencer has a combustion air intake port that opens in the radial direction with respect to the direction of the rotation axis and a recirculation gas intake port that opens in the rotation axis direction.

Therefore, the recirculated gas from which the droplet has been removed by the demister is sucked into the EGR blower, then flows into the silencer from the rotation axis direction, while the combustion air flows into the silencer from the radial direction. In addition, the combustion air (air sucked from the silencer) and the recirculating gas are merged on the upstream side of the compressor. Thereby, the EGR system can promote the mixing of the combustion air and the recycle gas before reaching the blades of the compressor. Here, since the air for combustion is air around the silencer, the moisture contained in the gas is less than the recycle gas, and mixing of both gases makes it difficult for moisture to condense in the mixture of the combustion air and the recycle gas. Further, since the recirculating gas flows in the axial direction, it can suppress the generation of droplets by colliding with the wall surface forming the recirculating gas passage in the silencer. Therefore, the EGR system can further suppress the occurrence of droplets when passing through the impeller of the compressor, so that the occurrence of the aging and corrugation can be further suppressed. Thus, the EGR system can reduce the damage of the bladed wheels and improve the life span of the blades even when EGR is performed.

The EGR system of the present invention is characterized in that the recirculation gas outlet of the EGR blower faces the recirculation gas inlet of the silencer.

Therefore, in the EGR system, the recirculating gas can minimize the passage length because the recirculating gas outlet of the EGR blower is opposed to the recirculating gas inlet of the silencer. In addition, the EGR system can minimize the bent portion of the pipe connecting the recirculating gas outlet port and the recirculating gas inlet port. Therefore, condensation of moisture in the recirculating gas can be further suppressed until reaching the compressor. Therefore, the EGR system can suppress the occurrence of droplets when passing through the impeller of the compressor, so that it is possible to further suppress the occurrence of this and collapse of the corona. Thus, the EGR system can reduce the damage of the bladed wheels and improve the life span of the blades even when EGR is performed.

The EGR system of the present invention is characterized in that the recirculation gas outlet of the EGR blower is arranged below the intake port of the recycle gas of the silencer in the height direction.

Therefore, the recirculation gas ejection port of the EGR blower is disposed below the recycling gas intake port of the silencer in the height direction. Therefore, even if the liquid contained in the recirculating gas is condensed to generate a droplet, the EGR system easily returns the droplet to the EGR blower. For this reason, the EGR system can suppress the flow of droplets to the vane of the compressor. As a result, the EGR system can suppress the occurrence of droplets when passing through the impeller of the compressor, so that it is possible to suppress the occurrence of this transition and corona transition. Thus, the EGR system can reduce the damage of the bladed wheels and improve the life span of the blades even when EGR is performed.

According to an aspect of the present invention, there is provided a diesel engine including a diesel engine main body, an inflator for introducing exhaust gas from the diesel engine main body, a supercharger for connecting a compressor coaxially rotating with the inflator via a rotation shaft, A demister for removing droplets contained in the recirculated gas washed with the scrubber; and an EGR valve disposed downstream of the recirculating gas flow of the demister The EGR blower includes a blower and a silencer in which one end of the EGR blower is connected to the compressor and the other end of the EGR blower is connected to the EGR blower. And is disposed on the end side.

Therefore, the recycle gas from which the droplet has been removed by the demister is sucked into the EGR blower, and then sent to the compressor via the silencer. Here, when the EGR blower is disposed on the other end side of the silencer, the passage length can be shortened while reducing the curvature of the passage between the silencer and the EGR blower. Even after the droplet is removed by the demister, the moisture of the recirculating gas is in a saturated state, so droplets may occur if the passage of the recirculating gas is long. On the other hand, in the diesel engine, by arranging the EGR blower on the other end side of the silencer, the passage length can be shortened while reducing the bent portion of the passage (piping) between the silencer and the EGR blower, The condensation of water in the recycle gas can be suppressed. As a result, the diesel engine can suppress the occurrence of the overrunning and the corrugation. The diesel engine is capable of suppressing the generation of the overrunning and the corona discharge, thereby suppressing the damage of the blades, thereby making it possible to increase the life span of the blades.

The diesel engine of the present invention further includes an auxiliary blower which is formed separately from the compressor and does not pass through the compressor but which feeds combustion air to the diesel engine main body, And is disposed on the inflator side.

Therefore, since the auxiliary blower is disposed on the side of the expander in the rotary shaft, it is unnecessary to provide a space for providing the auxiliary blower between the compressor and the EGR blower. Thus, the length of the passage between the compressor and the EGR blower can be shortened. Even when the droplet is removed by the demister, the moisture of the recirculating gas is saturated, so droplets may occur if the passage of the recirculating gas is long. However, while reducing the bend of the passage (piping) between the silencer and the EGR blower, It is possible to suppress the condensation of water in the recirculating gas until reaching the compressor. As a result, the diesel engine can suppress the occurrence of the overrunning and the corrugation. The diesel engine is capable of suppressing the generation of the overrunning and the corona discharge, thereby suppressing the damage of the blades, thereby making it possible to increase the life span of the blades.

According to the EGR system and the diesel engine of the present invention, damage to the blades of the compressor of the supercharger can be suppressed.

1 is a system diagram showing a diesel engine provided with an EGR system according to the first embodiment.
2 is a schematic view showing a diesel engine provided with the EGR system of the first embodiment.
3 is a front view showing the EGR system of the first embodiment.
4A is an enlarged front view of a part of the EGR system of the first embodiment.
4B is an enlarged top view of a part of the EGR system of the first embodiment.
5A is an enlarged front view of a part of the EGR system of the first modification of the first embodiment.
Fig. 5B is an enlarged view of a part of the EGR system of the first modification of the first embodiment.
6A is an enlarged front view of a part of the EGR system of the second modification of the first embodiment.
6B is an enlarged view of a part of the EGR system of the second modification of the first embodiment.
7 is a front view showing the EGR system of the second embodiment.

Hereinafter, preferred embodiments of the EGR system and the diesel engine according to the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the present invention is not limited to these embodiments, and when there are a plurality of embodiments, the embodiments may be combined.

[First Embodiment]

1 is a systematic diagram showing a diesel engine provided with an EGR system according to a first embodiment of the present invention. 2 is a schematic view showing a diesel engine provided with the EGR system of the first embodiment. 3 is a front view showing the EGR system of the first embodiment. 4A is an enlarged front view of a part of the EGR system of the first embodiment. 4B is an enlarged view of a part of the EGR system of the first embodiment.

1, the diesel engine 1 according to the first embodiment of the present invention includes a diesel engine main body 10 and an EGR system 100. [

2, the diesel engine main body 10 is a crosshead type diesel engine mainly used as a cycle for propelling a ship. The diesel engine main body 10 includes a base plate 11 located below, a base plate 11, And a cylinder jacket 13 formed on the furniture 12. As shown in Fig. The base plate 11, the furniture 12 and the cylinder jacket 13 are integrally fastened by a plurality of tie bolts and nuts extending in the axial direction of the piston. The diesel engine main body 10 is a diesel engine of a uniprochromatic type, and also a two-stroke diesel engine, in which the flow of small-sized exhaust gas in the cylinder is directed in one direction from below to the upper side,

A propeller shaft (not shown) is provided in the base plate 11 to drive and rotate a propeller (not shown) through a propeller shaft. At the upper end of the propeller shaft, a lower end of a connecting rod (not shown) is rotatably connected.

The furniture 12 is provided with a crosshead (not shown) for connecting the piston rod (not shown) and the connecting rod in a rotatable manner. That is, the lower end of the piston rod and the upper end of the connecting rod are connected to the crosshead. On both sides of the crosshead, a pair of sliding plates (not shown) extending in the axial direction of the piston are formed in a state of being fixed to the furniture 12.

A cylinder liner (not shown) is formed in the cylinder jacket 13, and a cylinder cover (not shown) is formed at an upper end of the cylinder liner. A piston (not shown) is formed in the space (cylinder) formed by the cylinder liner and the cylinder cover so as to be capable of reciprocating in the piston axial direction. The upper end of the piston rod is mounted on the lower end of the piston such that it can reciprocate in the piston axial direction. Here, the scavenging trunk 16 and the exhaust manifold 14 are communicated with the cylinder.

The scavenging trunk 16 communicates with the cylinder of the cylinder jacket 13 of the diesel engine body 10 as shown in Fig. The scavenging trunk 16 feeds combustion air or a combustion gas compressed by a mixture of combustion air and recirculating gas into the diesel engine main body 10. In the scavenging trunk 16, a combustion gas in which combustion air or a mixture of combustion air and recirculating gas is compressed is fed mainly from the supercharger 20. On the other hand, when the engine load of the diesel engine main body 10 is less than a predetermined value, combustion air is fed from the auxiliary blower 17 arranged close to the scavenging trunk 16. The combustion gas sent to the combustion chamber is burned together with the fuel, thereby reciprocating the piston in the cylinder.

The auxiliary blower 17 is an air compressor driven by an electric motor. The auxiliary blower 17 uses the air in the engine room in which the diesel engine 1 is disposed as combustion air to feed the combustion air to the scavenging trunk 16 without passing through the turbocharger 20. [ The auxiliary blower 17 of the first embodiment of the present invention is disposed on the inflator side (the side opposite to the silencer) of the supercharger 20 to be described later.

The exhaust manifold 14 is in communication with the cylinder of the cylinder jacket 13 of the diesel engine body 10 as shown in Fig. The exhaust manifold 14 is a tank for temporarily storing exhaust gas generated by combustion in the cylinder to make it a static pressure. The exhaust manifold 14 feeds exhaust gas having a constant pressure to the supercharger 20.

Next, an EGR system 100 according to the present embodiment will be described with reference to Fig. The EGR system 100 of the present embodiment includes a turbocharger 20, a scrubber 101, a demister 102, and an EGR blower 104. Here, the EGR system 100 is a system in which a part of the exhaust gas discharged from the diesel engine body 10 is recycled to the diesel engine body 10 as a recirculating gas and used as a combustion gas. The EGR system 100 in this embodiment is disposed on the diesel engine body 10 as shown in Fig. The diesel engine body 10 is woven on the outer circumferential surface of a chair that can be accessed by personnel of each device of the EGR system 100.

The supercharger 20 is provided with an expander (turbine) 21, a compressor (compressor) 22, and a silencer 23. The inflator 21 is provided with a turbine disk (not shown) including a turbine blade (not shown) therein. The compressor (22) is provided with a bladder (not shown) including a compressor blade (not shown) therein. The supercharger 20 is connected such that the blades of the compressor 22 and the turbine disk of the inflator 21 are freely rotatable about a rotor axis (rotation axis). The rotor of the supercharger 20 includes an expander (turbine) 21, a compressor (compressor) 22, and a rotor shaft (rotary shaft). The rotor shaft is axially supported by a bearing stand (not shown) disposed between the inflator 21 and the compressor 22. The supercharger 20 is rotated by the exhaust gas discharged from the diesel engine body 10 through the exhaust manifold 14. The turbocharger 20 is configured such that the rotation of the inflator 21 is transmitted by the rotor so that the compressor 22 rotates and the compressor 22 compresses the combustion air and / or the recirculating gas. The combustion gas obtained by compression by the compressor 22 is supplied to the diesel engine body 10 through the scavenging trunk 16. On the other hand, as shown in Fig. 1, the exhaust gas from which energy has been recovered by passing through the inflator 21 is discharged to the exhaust gas pipe 15. [

The silencer 23 is a hollow cylindrical device connected to the compressor 22 and has one end portion (one end surface) 23a in the axial direction of the compressor 22 so that the axial direction of the cylinder is coincident with the rotor axis (22). The silencer 23 is formed in a radial manner with a passage (combustion air passage) for feeding air in the engine room in which the diesel engine 1 is disposed as combustion air to the compressor 22 . In addition, the silencer 23 has a silencer element which is not shown. The silencer element suppresses the noise generated by the driving of the compressor 22 from being transmitted to the engine room through the combustion air passage. The silencer 23 in the present embodiment is provided with an opening (recirculating gas inlet) 23c at the other end (the other end face) 23b in the axial direction. 3, the direction of the axis of the rotary shaft of the rotor shaft is referred to as a rotational axis direction (also referred to as an axial direction), and the direction perpendicular to the plane on which the diesel engine body 10 is provided is referred to as a height direction And a direction perpendicular to both the rotational axis direction and the height direction is defined as the width direction.

The scrubber 101 is a venturi type scrubber, and has a hollow throat portion, a venturi portion into which exhaust gas is introduced, and an enlarged portion that is stepwise returned to the original flow rate. The scrubber 101 has a liquid injection portion for injecting a liquid with respect to the recycle gas in the case where a part of the exhaust gas discharged into the exhaust gas pipe 15 is recycled to the diesel engine body 10 as a recycle gas . The scrubber 101 removes (cleans) harmful substances such as fine particles PM, such as SOx and sold, by spraying a liquid against the recirculating gas.

Here, as shown in Fig. 3, the scrubber 101 is disposed on the other end 23b side of the silencer 23 in the axial direction. More specifically, the scrubber 101 is disposed apart from the other end 23b in the axial direction of the silencer 23 in the axial direction. Further, the scrubber 101 of the present embodiment is a Venturi type scrubber, but it is not limited to this configuration.

The demister 102 is a hollow rectangular casing and is connected to the outlet of the scrubber 101. In the demister 102, a liquid is sprayed from the scrubber 101, whereby a recirculating gas from which toxic substances are removed and a drainage stream are flowed. The demister 102 separates the recirculating gas and the draining, and removes the droplets contained in the recirculating gas. The separated recycle gas is discharged from the recycle gas discharge port of the demister 102 to the EGR blower 104. On the other hand, the separated drained liquid and the removed liquid droplets are discharged to the collecting tank 103 disposed under the demister 102. The drained liquid and the liquid droplets discharged into the collecting tank 103 are neutralized by a system of a cleaning liquid not shown and then returned to the liquid ejecting portion of the scrubber 101 and reused.

Here, as shown in Fig. 3, the demister 102 is disposed on the other end 23b side of the silencer 23 in the axial direction. More specifically, the demister 102 is disposed apart from the other end 23b in the axial direction of the silencer 23 in the axial direction. Desirably, the demister 102 is spaced apart from the silencer 23 in the axial direction as in the present embodiment, but it may be configured such that a part thereof overlaps the silencer 23 in the axial direction.

The EGR blower 104 is disposed above the demister 102. The EGR blower 104 sucks the recycle gas from which the droplet has been removed by the demister 102 from the recirculation gas ejection port of the demister 102 and recycles it from the recirculation gas ejection port 104a to the recirculation gas inlet 23c. The recirculating gas outlet 104a of the EGR blower 104 is connected to the recirculating gas inlet 23c of the silencer 23 via a pipe 105. [ Here, the pipe 105 functions as a passage of the recirculating gas.

Here, as shown in Fig. 3, the EGR blower 104 is disposed on the other end 23b side of the silencer 23 in the axial direction. More specifically, the recirculation gas discharge port 104a of the EGR blower 104 is arranged so as to face the recirculating gas inlet port 23c of the other end 23b in the axial direction of the silencer 23 Viewing position). In this case, as shown in Figs. 4A and 4B, it is preferable that the EGR blower 104 and the silencer 23 are arranged so that the pipe 105 becomes a straight pipe. In other words, the EGR blower 104 and the silencer 23 are arranged so that the recirculation gas inlet port 23c of the other end 23b in the axial direction of the silencer 23 and the recirculation gas outlet port 104a of the EGR blower 104 Width direction and the height direction. The recirculation gas discharge port 104a of the EGR blower 104 may be in contact with the recirculating gas inlet port 23c of the silencer 23 in the axial direction without being separated therefrom. In this case, the pipe 105 may not be formed, or the EGR blower 104 and the pipe 105 may be integrated.

As described above, the recirculating gas fed from the EGR system 100 to the recirculating gas inlet 23c of the silencer 23 is supplied from the combustion air passage radially formed around the axial direction of the silencer 23 to the combustion air And the inside of the silencer 23 to be a mixer. The mixer is compressed by the compressor (22) and supplied to the diesel engine body (10) via the small trunk (16) as a combustion gas.

The EGR system 100 according to the first embodiment of the present invention is configured such that the EGR blower 104 is disposed on the other end (other end face) 23b side of the silencer 23 in the direction of the rotation axis of the inflator 21 . As a result, the passage length can be shortened while reducing the curvature of the passage (the pipe 105) between the silencer 23 and the EGR blower 104. Even if the droplet is removed by the demister 102, since the moisture of the recirculating gas is saturated, a droplet may occur if the passage of the recirculating gas is long. However, the passage between the silencer 23 and the EGR blower 104 (105), the length of the passage can be shortened, and condensation of moisture in the recirculating gas can be suppressed until reaching the compressor. As a result, the amount of liquid droplets passing through the impeller of the compressor can be suppressed, so that the occurrence of deflection and corrugation can be suppressed. Thus, damage to the wing car can be suppressed, and the life span of the wing car can be improved.

In the EGR system 100 according to the first embodiment of the present invention, the demister 102 is disposed on the other end 23b side of the silencer 23. As a result, the demister 102 and the silencer 23 as well as the passage between the EGR blower 104 and the silencer 23 exist because of the presence of the demister 102 on the other end 23b side of the silencer 23, It is possible to shorten the length of the passage while suppressing the condensation of moisture in the recycle gas until reaching the compressor. This makes it possible to further suppress the amount of liquid droplets passing through the impeller of the compressor, so that the occurrence of the aging and corrugation can be further suppressed. As a result, damage to the blades can be further suppressed and the life span of the blades can be improved even when the EGR is performed.

The EGR system 100 according to the first embodiment of the present invention has the scrubber 101 mounted on the upper side of the demister 102 and disposed on the other end 23b side of the silencer 23. Thereby, the recycle gas containing the drainage and droplets generated from the scrubber 101 is directly introduced into the demister 102 from the scrubber 101. [ It is necessary to manage the apparatus constituting the EGR system 100 so that corrosion does not occur. Since the scrubber 101 and the demister 102 need to be controlled so that corrosion does not occur in the equipment constituting the EGR system 100, It is possible to minimize the score of a device to be managed. Therefore, the burden of the maintenance can be greatly reduced.

The EGR system 100 according to the first embodiment of the present invention is characterized in that the silencer 23 has a combustion air intake port opened in the radial direction with respect to the direction of the rotation axis and a recirculation gas intake port 23c opened in the rotation axis direction, Respectively. As a result, the recycle gas from which the droplet has been removed by the demister 102 is sucked into the EGR blower 104 and then flows into the silencer 23 from the direction of the rotation axis, while the combustion air flows from the radial direction into the silencer 23 . In addition, the combustion air (air sucked from the silencer 23) and the recirculating gas are merged on the upstream side of the compressor 22. Therefore, mixing of the combustion air and the recycle gas can be promoted before reaching the blades of the compressor 22. [ Since the combustion air is air around the silencer 23, there is a high possibility that the moisture contained in the gas is less than the recirculation gas. By mixing both gases, moisture is condensed from the mixture of the combustion air and the recycle gas . In addition, since the recirculating gas flows in the axial direction, it is possible to suppress generation of droplets by colliding with the wall surface of the silencer 23 forming the recirculating gas passage. This makes it possible to further suppress the amount of liquid droplets passing through the impeller of the compressor 22, so that the occurrence of this and corrugation can be further suppressed. As a result, damage to the blades can be further suppressed and the life span of the blades can be improved even when the EGR is performed.

The EGR system 100 according to the first embodiment of the present invention is configured such that the recirculation gas outlet 104a of the EGR blower 104 faces the recirculation gas inlet 23c of the silencer 23. Thus, the recirculating gas can minimize the passage length because the recirculating gas outlet 104a of the EGR blower 104 and the recirculating gas inlet 23c of the silencer 23 are opposed to each other. It is also possible to minimize the bent portion of the pipe connecting the recirculation gas outlet 104a and the recirculation gas inlet 23c. Therefore, condensation of moisture in the recirculating gas can be further suppressed until reaching the compressor. This makes it possible to further suppress the amount of liquid droplets passing through the impeller of the compressor, so that the occurrence of the aging and corrugation can be further suppressed. As a result, damage to the blades can be further suppressed and the life span of the blades can be improved even when the EGR is performed.

The diesel engine 1 according to the first embodiment of the present invention is configured such that the EGR blower 104 is disposed on the other end (other end face) 23b side of the silencer 23 in the direction of the rotation axis of the inflator 21 . Thereby, the diesel engine 1 can shorten the passage length while reducing the bent portion of the passage (the pipe 105) between the silencer 23 and the EGR blower 104. Therefore, the recycle gas from which the droplet has been removed by the demister 102 is sucked into the EGR blower 104, and then sent to the compressor 22 via the silencer 23. When the EGR blower 104 is disposed on the other end 23b side of the silencer 23, the length of the passage can be shortened while reducing the curvature of the passage between the silencer 23 and the EGR blower 104 have. The diesel engine 1 is operated by the silencer 23 and the EGR blower 23 so that the amount of the recirculated gas in the exhaust gas can be reduced even if the droplet is removed by the demister 102, The condensation of moisture in the recirculating gas can be suppressed until reaching the compressor 22 since the passage length can be shortened while reducing the bent portion of the passage (the pipe 105) Thereby, the diesel engine 1 can suppress the occurrence of the overrunning and the corrugation. The diesel engine 1 is capable of suppressing the generation of the overrunning and the corona discharge, thereby suppressing the damage of the blades, and the longevity of the blades can be increased.

The diesel engine 1 according to the first embodiment of the present invention is formed separately from the compressor 22 and does not pass through the compressor 22 and is supplied to the auxiliary blower 17, and the auxiliary blower 17 is disposed on the side of the inflator 21 on the rotating shaft. Thus, since the auxiliary blower 17 is disposed on the side of the expander 21 on the rotating shaft, it is necessary to form a space for installing the auxiliary blower 17 between the compressor 22 and the silencer 23 and the EGR blower 104 . As a result, the passage length between the compressor 22 and the EGR blower 104 can be shortened. The diesel engine 1 is operated by the silencer 23 and the EGR blower 23 so that the amount of the recirculated gas in the exhaust gas can be reduced even if the droplet is removed by the demister 102, The condensation of moisture in the recirculating gas can be suppressed until reaching the compressor 22 since the passage length can be shortened while reducing the bent portion of the passage (the pipe 105) Thereby, the diesel engine 1 can suppress the occurrence of the overrunning and the corrugation. The diesel engine 1 is capable of suppressing the generation of the overrunning and the corona discharge, thereby suppressing the damage of the blades, and the longevity of the blades can be increased.

[First Modification of First Embodiment]

5A is an enlarged front view of a part of the EGR system of the first modification of the first embodiment. Fig. 5B is an enlarged view of a part of the EGR system of the first modification of the first embodiment. Next, an EGR system 100a according to a first modification of the first embodiment of the present invention will be described with reference to Figs. 5A and 5B. Members having the same functions as those of the above-described first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

5A and 5B, the EGR system 100a according to the first modification of the first embodiment of the present invention differs from the EGR gas blower 104 according to the first embodiment in the recirculation gas discharge port 104a and the recirculation gas intake port 23c of the silencer 23 are arranged at different positions in the width direction. More specifically, the pipe 105 'is configured to have a bent portion in the width direction. 5A and 5B, the recirculating gas outlet 104a of the EGR blower 104 and the recirculating gas inlet 23c of the silencer 23 are arranged at the same position in the height direction , Or may be disposed at different positions.

As described above, the EGR system 100a according to the first modification of the first embodiment of the present invention has the recirculation gas outlet 104a of the EGR blower 104 and the recirculation gas inlet 23c of the silencer 23, Are arranged at different positions in the width direction, the silencer (23) can be disposed apart from the region where the temperature of the air in the engine room is high. Therefore, the EGR system 100a can reduce the temperature of the combustion air sucked into the silencer 23 while shortening the passage length of the recirculating gas. Therefore, the EGR system 100a can improve the engine performance while suppressing the inflow of the droplets to the vane wheels.

[Second Modification of First Embodiment]

6A is an enlarged front view of a part of the EGR system of the second modification of the first embodiment. 6B is an enlarged view of a part of the EGR system of the second modification of the first embodiment. Next, an EGR system 100b according to a second modification of the first embodiment of the present invention will be described with reference to Figs. 6A and 6B. Members having the same functions as those of the above-described first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

6A and 6B, the EGR system 100b according to the second modification of the first embodiment of the present invention differs from the EGR gas blower 104 according to the first embodiment in that the recirculation gas discharge port 104a and the recirculation gas intake port 23c of the silencer 23 are arranged at different positions in the height direction. More specifically, the pipe 105 '' is configured to have a bent portion in the height direction. 6A and 6B, the recirculating gas outlet 104a of the EGR blower 104 and the recirculating gas inlet 23c of the silencer 23 are arranged at the same position in the width direction, but even if they are disposed at different positions do.

As described above, in the EGR system 100b, since the recirculation gas outlet 104a of the EGR blower 104 and the recirculation gas inlet 23c of the silencer 23 are arranged at different positions in the height direction, the EGR Even when a droplet is generated between the recirculation gas outlet 104a of the blower 104 and the recirculation gas inlet 23c of the silencer 23, the droplet is easily returned to the direction of the EGR blower 104. For this reason, the EGR system 100b can suppress the inflow of droplets to the blades.

[Second Embodiment]

7 is a front view showing an EGR system according to a second embodiment of the present invention. Members having the same functions as those of the above-described first embodiment are denoted by the same reference numerals, and a detailed description thereof will be omitted.

The EGR system 110 according to the second embodiment of the present invention includes a scrubber 101, a demister 102, and an EGR blower 114 as shown in Fig. Further, the scrubber 101 and the demister 102 are the same as those in the first embodiment, and a description thereof will be omitted.

The EGR blower 114 is disposed above the demister 102. The EGR blower 114 sucks the recycle gas from which the droplet has been removed by the demister 102 from the recirculation gas discharge port of the demister 102 and discharges the recirculated gas from the recirculation gas discharge port 114a to the recirculation gas inlet 23c. The recirculation gas discharge port 114a of the EGR blower 114 is connected to the recirculation gas intake port 23c of the silencer 23 via a pipe 115. Here, the pipe 115 functions as a passage of the recirculating gas.

Here, the EGR blower 114 of the second embodiment of the present invention is formed so that the recirculation gas discharge port 114a opens in the height direction. The recirculating gas outlet 114a of the EGR blower 114 is connected to the recirculating gas inlet 115a of the pipe 115 opened in the height direction. The recirculating gas introduced into the pipe 115 is discharged from the recirculating gas inlet 23c of the silencer 23 connected to the recirculating gas outlet 115b of the pipe 115 opened in the direction of the rotational axis.

The EGR blower 114 is disposed on the side of the other end 23b in the axial direction of the silencer 23. More specifically, the EGR blower 114 is arranged such that the recirculation gas outlet 114a is spaced apart from the recirculation gas inlet 23c of the other end 23b in the axial direction of the silencer 23 in the axial direction do. In this case, as shown in Fig. 6, the piping 115 has the recirculation gas inlet 115a opened in the height direction and the recirculation gas outlet 115b opened in the rotation axis direction. Further, the EGR blower 114 and the pipe 115 may be integrated.

As described above, the recirculating gas fed from the EGR system 110 to the recirculating gas inlet 23c of the silencer 23 is supplied from the combustion air passage radially formed around the axial direction of the silencer 23 to the combustion air And the silencer (23). After being mixed in the inside of the silencer 23, the mixer is compressed by the compressor 22 and supplied to the diesel engine body 10 via the scavenging trunk 16 as a combustion gas.

The recirculation gas outlet 114a of the EGR blower 114 is disposed below the recirculation gas intake port 23c of the silencer 23 in the height direction in the EGR system 110 of the second embodiment. Therefore, even when a droplet occurs between the recirculation gas outlet 114a of the EGR blower 114 and the recirculation gas inlet 23c of the silencer 23, the droplet is easily returned to the EGR blower 114. Therefore, the EGR system 110 can suppress the inflow of droplets into the vane wheel.

In the above-described embodiment, the marine two-stroke engine is used as the diesel engine. However, the invention is also applicable to other diesel engines equipped with the EGR system.

1: Diesel engine
10: Diesel engine body
11: Plays
12: Furniture
13: Cylinder jacket
14: Exhaust manifold
15: Exhaust gas piping
16: Exhaust trunk
17: auxiliary blower
20: supercharger
21: Inflator (turbine)
22: Compressor (compressor)
23: Silencers
100, 110: EGR system
101: Scrubber
102: Demister
103: Collecting tank
104, 114: EGR blower
105, 105 ', 105'', 115: piping

Claims (8)

A supercharger in which an expander and a compressor are connected by a rotary shaft,
A scrubber for cleaning the recirculating gas, which is a part of the exhaust gas discharged from the inflator, with a liquid;
A demister for removing droplets contained in the recycle gas washed with the scrubber,
An EGR blower disposed downstream of the recycle gas flow of the demister,
And a silencer having one end in the direction of the rotational axis connected to the compressor and the other end in the direction of the rotational axis connected to the EGR blower,
Wherein the EGR blower is disposed on the other end side of the silencer in the direction of the rotation axis. The method according to claim 1,
And the demister is disposed on the other end side of the silencer. 3. The method of claim 2,
Wherein the scrubber is mounted on the top of the demister and is disposed on the other end side of the silencer. 4. The method according to any one of claims 1 to 3,
The silencer,
A combustion air inlet opening in the radial direction with respect to the direction of the rotation axis,
And a recirculating gas inlet opening in the direction of the axis of rotation. 5. The method of claim 4,
And the recirculation gas outlet of the EGR blower is opposed to the recirculation gas inlet of the silencer. 6. The method of claim 5,
Wherein the recirculation gas outlet of the EGR blower is disposed below the recirculation gas inlet of the silencer in the height direction. A diesel engine main body,
A supercharger in which an exhaust gas of the diesel engine main body is introduced, a supercharger in which a compressor coaxially rotating with the inflator is connected by a rotation shaft,
A scrubber for cleaning the recirculating gas, which is a part of the exhaust gas discharged from the inflator, with a liquid;
A demister for removing droplets contained in the recycle gas washed with the scrubber,
An EGR blower disposed downstream of the recycle gas flow of the demister,
And a silencer having one end in the direction of the rotational axis connected to the compressor and the other end in the direction of the rotational axis connected to the EGR blower,
Wherein the EGR blower is disposed on the other end side of the silencer in the direction of the rotation axis. 8. The method of claim 7,
And an auxiliary blower which is separately formed from the compressor and does not pass through the compressor, and which supplies combustion air to the diesel engine body,
Wherein the auxiliary blower is disposed on the inflator side in the direction of the rotation axis.

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