WO2017138340A1

WO2017138340A1 - Demister unit and egr system

Info

Publication number: WO2017138340A1
Application number: PCT/JP2017/002160
Authority: WO
Inventors: 和久伊藤; 平岡　直大; 中川　貴裕; 哲司上田
Original assignee: 三菱重工業株式会社; 株式会社ジャパンエンジンコーポレーション
Priority date: 2016-02-10
Filing date: 2017-01-23
Publication date: 2017-08-17
Also published as: CN108697957A; KR20180063308A; CN108697957B; JP6171194B1; JP2017140582A; KR102133162B1

Abstract

A demister unit and an EGR system that have provided therein: a hollow casing (51) having an exhaust gas inlet (61) and outlet (62); a baffle plate (52) forming a curved upstream-side flowpath (64) as a result of being arranged facing the inlet (61) inside the casing (51); and a demister main body (55) arranged further on the downstream side in the exhaust gas flow direction than the upstream-side flowpath (64), inside the casing (51), and removing mist from the exhaust gas. The inlet (61) is arranged displaced toward one side in the horizontal direction, from the intermediate position in the horizontal direction in the casing (51).

Description

Demister unit and EGR system

The present invention relates to a demister unit that removes mist from exhaust gas, and an EGR system to which this demister unit is applied.

Since the exhaust gas discharged from the boiler via the wet exhaust gas treatment apparatus contains mist, it is necessary to remove the mist contained in the exhaust gas. There exists a demister unit as what removes the mist contained in waste gas, for example, there exist some which were described in following patent document 1. FIG. In the demister unit described in Patent Document 1, a baffle plate is disposed to face the inlet in the casing, thereby forming a bent upstream flow path and providing a demister main body on the downstream side thereof. It is a thing.

JP, 2015-165103, A

The demister unit removes the mist contained in the exhaust gas by passing the exhaust gas therethrough. If the flow velocity of the exhaust gas passing through the demister main body is too fast, the mist removal performance is degraded. Therefore, in order to improve the mist removal performance, it is effective to reduce the flow velocity of the exhaust gas passing through the demister main body by lengthening the flow path length of the demister main body. However, when the flow path length of the demister main body is increased, the demister main body becomes large, and the demister unit itself is increased in size. When the demister unit is increased in size, there is a problem that the demister unit can not be installed at a desired position due to restrictions imposed by the installation position of the demister unit.

The present invention solves the above-mentioned problems, and an object of the present invention is to provide a demister unit and an EGR system which aim to improve the mist removal performance and to suppress the enlargement of the apparatus.

A demister unit according to the present invention for achieving the above object comprises a casing having a hollow shape and having a fluid inlet and outlet, and a bending flow by being disposed in the casing opposite to the inlet. A baffle plate forming a passage, and a demister main body disposed in the casing downstream of the bending flow passage in the fluid flow direction to remove mist from the fluid, the inlet portion being horizontal in the casing It is characterized in that it is disposed to be shifted to one side in the horizontal direction from the middle position in the direction.

Therefore, the fluid introduced into the casing from the inlet collides with the baffle plate, and the contained mist forms droplets and adheres to the baffle plate and flows down. Then, the fluid from which a part of the mist has been removed flows through the bending flow path, whereby the mist is further removed by centrifugal force, and finally the remaining mist is removed by the demister main body. Here, since the inlet portion of the fluid is disposed on one side in the horizontal direction in the casing, the fluid introduced into the casing from the inlet portion collides with the baffle plate and flows to the other side in the horizontal direction, After flowing through the flexing channel, it turns horizontally before reaching the demister main body. As a result, the flow path of the fluid becomes long and the flow velocity decreases, so that the mist removal performance can be improved, and the enlargement of the apparatus can be suppressed.

In the demister unit of the present invention, the inlet portion is disposed on one side in the horizontal direction from the horizontal intermediate position in the casing at a half or more of the horizontal opening length in the inlet portion. It is characterized.

Therefore, by displacing the inlet portion of the fluid to one side in the horizontal direction by an appropriate amount or more, the fluid after colliding with the baffle plate can be properly turned horizontally, and the fluid flow path is lengthened to The flow rate can be reduced.

In the demister unit of the present invention, the baffle plate is provided so as to be suspended from the ceiling portion of the casing so that a passage opening is provided downward, and the demister main body is the ceiling from the passage opening in the casing. A detour flow path is provided between the bottom of the casing and the demister supporting plate so as to be in fluid communication with the passage opening to horizontally turn fluid by being fixed on the demister supporting plate fixed on the part side. It is characterized by

Therefore, by providing a bypass flow passage communicating with the passage opening between the bottom of the casing and the demister support plate to horizontally swirl the fluid, the fluid can be properly horizontally swirled in the bypass flow passage. The flow path can be lengthened to reduce the flow rate of the fluid.

The demister unit according to the present invention is characterized in that a perforated plate is disposed at the passage opening at a predetermined distance from the bottom of the casing, and the perforated plate is provided up to the middle of the fluid flow direction.

Therefore, by providing the porous plate up to the middle part in the fluid flow direction, the space part on the downstream side of the fluid can be expanded, and the flow path of the fluid can be lengthened to reduce the flow velocity.

The demister unit according to the present invention is characterized in that a receiving member is provided for receiving droplets generated by the collision of the fluid with the baffle plate.

Therefore, the fluid introduced into the casing from the inlet collides with the baffle plate so that the contained mist drops as droplets and adheres to the baffle plate, and flows down the flat portion of the baffle plate by its own weight, and the receiving member It is received by Therefore, the fluid flowing through the curved flow channel does not again take in droplets as mist, and it is possible to improve the mist removal efficiency by suppressing the reintroduction of the mist removed from the fluid into the fluid.

In the EGR system according to the present invention, the exhaust gas recirculation line recirculates a part of the exhaust gas discharged from the engine to the engine as a combustion gas, and the liquid for the combustion gas flowing in the exhaust gas recirculation line It is characterized by comprising a scrubber to be injected, and the demister unit to which the combustion gas discharged from the scrubber is introduced.

Therefore, when a part of the exhaust gas discharged from the engine passes through the exhaust gas recirculation line, the scrubber removes the harmful substances by injecting a liquid to the combustion gas flowing through the exhaust gas recirculation line, After the mist contained by the demister unit is removed, it is supplied to the engine. And, in the demister unit, since the inlet portion of the fluid is arranged to be shifted to one side in the horizontal direction in the casing, the fluid introduced into the casing from the inlet portion collides with the baffle plate and the other side in the horizontal direction And, after flowing through the bending channel, turn horizontally before reaching the demister main body. As a result, the flow path of the fluid becomes long and the flow velocity decreases, so that the mist removal performance can be improved, and the enlargement of the apparatus can be suppressed.

According to the demister unit and the EGR system of the present invention, the mist removal performance can be improved, and the enlargement of the device can be suppressed.

FIG. 1 is a schematic view showing a diesel engine equipped with an EGR system to which the demister unit of the present embodiment is applied. FIG. 2 is a schematic block diagram showing the EGR system of the present embodiment. FIG. 3 is a longitudinal sectional view showing the demister unit of the present embodiment. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG. 3 showing a horizontal cross section of the demister unit. FIG. 5 is a cross-sectional view taken along the line VV of FIG. 3 showing the inlet of the demister unit. FIG. 6 is a perspective view with a part of the demister unit cut away.

Hereinafter, preferred embodiments of a demister unit and an EGR system according to the present invention will be described in detail with reference to the attached drawings. Note that the present invention is not limited by the embodiments, and in the case where there are a plurality of embodiments, the present invention also includes those configured by combining the respective embodiments.

First Embodiment
FIG. 1 is a schematic view showing a diesel engine provided with an EGR system to which the demister unit of the first embodiment is applied, and FIG. 2 is a schematic configuration view showing an EGR system according to the first embodiment.

In the first embodiment, as shown in FIG. 1, the marine diesel engine 10 includes an engine body 11, a supercharger 12, and an EGR system 13.

As shown in FIG. 2, although not shown, the engine body 11 is a propulsion engine (main engine) that drives and rotates a propulsion propeller via a propeller shaft. The engine body 11 is a uniflow scavenging diesel engine, which is a two-stroke diesel engine, in which the flow of intake and exhaust in the cylinder is one direction from the lower side to the upper side, and the residual of the exhaust is eliminated. It is. The engine body 11 includes a plurality of cylinders (combustion chambers) 21 in which pistons move up and down, a scavenging air trunk 22 in communication with the cylinders 21, and an exhaust manifold 23 in communication with the cylinders 21. The scavenging ports 24 are provided between the cylinders 21 and the scavenging trunk 22, and the exhaust flow path 25 is provided between the cylinders 21 and the exhaust manifold 23. The engine body 11 has the scavenging air trunk 22 connected to the air supply line G1 and the exhaust manifold 23 connected to the exhaust line G2.

The turbocharger 12 is configured by connecting a compressor 31 and a turbine 32 so as to rotate integrally with a rotating shaft 33. In the turbocharger 12, the turbine 32 is rotated by the exhaust gas discharged from the exhaust line G2 of the engine body 11, the rotation of the turbine 32 is transmitted by the rotation shaft 33, and the compressor 31 is rotated. And / or compresses the recirculated gas and supplies it to the engine body 11 from the air supply line G1. The compressor 31 is connected to a suction line G6 for drawing air from the outside (atmosphere).

The turbocharger 12 is connected to an exhaust line G3 for discharging the exhaust gas that has rotated the turbine 32, and the exhaust line G3 is connected to a chimney (funnel) not shown. Further, an EGR system 13 is provided between the exhaust line G3 and the air supply line G1.

The EGR system 13 includes exhaust gas recirculation lines G4, G5, G7, a scrubber 42, a demister unit 14, and an EGR blower (blower) 47. The EGR system 13 mixes a part of the exhaust gas discharged from the marine diesel engine 10 with air, and then compresses the mixture by the turbocharger 12 and recycles it to the marine diesel engine 10 as a combustion gas, thereby causing combustion. It suppresses the formation of NOx. Although the EGR system is installed to extract a part of the exhaust gas from the downstream side of the turbine 32 here, the EGR system may be installed to extract a part of the exhaust gas from the upstream side of the turbine 32 .

One end of the exhaust gas recirculation line G4 is connected to the middle of the exhaust line G3. The exhaust gas recirculation line G4 is provided with an EGR inlet valve (opening / closing valve) 41A, and the other end is connected to the scrubber 42. The EGR inlet valve 41A opens / closes the exhaust gas branched from the exhaust line G3 to the exhaust gas recirculation line G4 by opening / closing the exhaust gas recirculation line G4. The EGR inlet valve may be a flow rate adjusting valve, and the flow rate of the exhaust gas passing through the exhaust gas recirculation line G4 may be adjusted.

The scrubber 42 is a Venturi-type scrubber, and includes a hollow throat 43, a venturi 44 into which exhaust gas is introduced, and an enlarged portion 45 that gradually returns to the original flow velocity. The scrubber 42 includes a water injection unit 46 that injects water (liquid) to the exhaust gas introduced into the venturi unit 44. The scrubber 42 is connected to an exhaust gas recirculation line G5 for discharging waste water containing harmful substances and exhaust gases from which harmful substances such as SOx and particulates (PM) such as dust are removed. In addition, in this embodiment, although a Venturi type is employ | adopted as a scrubber, it is not limited to this structure.

The exhaust gas recirculation line G5 is provided with a demister unit 14 and an EGR blower 47.

The demister unit 14 separates the waste gas and the waste gas from which harmful substances have been removed by water injection. The demister unit 14 is provided with a drainage circulation line W1 that circulates the drainage to the water injection unit 46 of the scrubber 42. The drainage circulation line W1 is provided with a hold tank 49 and a pump 50 for temporarily storing drainage.

The EGR blower 47 guides the exhaust gas in the scrubber 42 to the demister unit 14 from the exhaust gas recirculation line G5.

The exhaust gas recirculation line G7 has one end connected to the EGR blower 47 and the other end connected to the compressor 31 via a mixer (not shown), and the exhaust gas is sent to the compressor 31 by the EGR blower 47. The exhaust gas recirculation line G7 is provided with an EGR outlet valve (on-off valve or flow control valve) 41B. The air from the suction line G6 and the exhaust gas (recirculation gas) from the exhaust gas recirculation line G7 are mixed in a mixer to generate a combustion gas. Note that this mixer may be provided separately from the silencer, or the silencer may be configured to have a function of mixing exhaust gas and air without separately providing a mixer. The supercharger 12 can supply the combustion gas compressed by the compressor 31 from the air supply line G1 to the engine body 11, and an air cooler (cooler) 48 is provided on the air supply line G1. The air cooler 48 cools the combustion gas by exchanging heat between the combustion gas compressed by the compressor 31 and having a high temperature and the cooling water.

Hereinafter, the demister unit 14 described above will be described in detail. 3 is a longitudinal sectional view showing the demister unit of this embodiment, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3 showing the horizontal section of the demister unit, and FIG. 5 is a diagram showing the inlet of the demister unit in FIG. FIG. 6 is a perspective view in which a part of the demister unit is cut away.

The demister unit 14 includes a casing 51, a baffle plate 52, a demister support plate 54, and a demister main body 55, as shown in FIGS.

The casing 51 has a hollow rectangular box shape, and is configured as a container that forms an internal space. That is, the casing 51 has a ceiling 51a located on the upper side in the vertical direction, a left wall 51b and a right wall 51c located on the left and right sides in the horizontal direction, and a bottom 51d located on the lower side in the vertical direction. It is formed of an upstream wall 51e located on the near side in the horizontal direction and a downstream wall 51f located on the far side in the horizontal direction. In the casing 51, an inlet portion 61 into which exhaust gas and drainage are introduced is formed on the upper side of the upstream wall 51e located at one end (right end in FIG. 3) on the front side. Further, the casing 51 is provided with an outlet 62 through which exhaust gas (fluid) is discharged to the ceiling 51 a at the other end (left end in FIG. 3) on the back side.

Here, the inlet portion 61 is disposed at a predetermined distance L on one side in the horizontal direction (right side in FIG. 5) from an intermediate position in the width direction (horizontal direction) of the casing 51. In this case, it is desirable that the inlet portion 61 be disposed on one side in the width direction from the middle position of the casing 51 at a half or more of the horizontal opening length D in the inlet portion 61. Here, since the inlet portion 61 has a cylindrical shape, the inlet portion 61 is disposed on one side in the width direction from the middle position of the casing 51 so as to be displaced by a radius (1/2 of D) or more of the inlet portion 61. It will be. On the other hand, the outlet portion 62 is provided at an intermediate position in the width direction (horizontal direction, left and right direction in FIG. 5) of the casing 51. The inlet 61 and the outlet 62 have a cylindrical shape, and are cylindrical or rectangular.

The baffle plate 52 is disposed in the casing 51 along the vertical direction so as to face the inlet 61 and be parallel to the upstream wall 51e. The baffle plate 52 is formed of a flat plate through which exhaust gas and droplets can not pass, and the upper end portion thereof is closely fixed to the ceiling portion 51a and the left and right side portions are the left wall portion 51b and the right The passage opening 63 is formed by positioning the lower end portion at a predetermined interval with respect to the bottom portion 51d while being fixed in close contact with the wall 51c. Therefore, the exhaust gas introduced from the inlet portion 61 flows downward between the upstream wall portion 51 e and the baffle plate 52 in the vertical direction, is bent through the passage opening portion 63, and then flows horizontally as a bent flow passage flowing in the horizontal direction. A flow path 64 is formed.

In the present embodiment, the distance from the inlet 61 opened to the upstream wall 51 e of the casing 51 to the flat surface 52 a of the baffle plate 52 is set to be equal to or less than the inner diameter of the inlet 61. Therefore, the exhaust gas introduced into the casing 51 from the inlet portion 61 collides with the baffle plate 52 and then flows along the upstream side flow path 64. That is, the exhaust gas introduced into the casing 51 from the inlet portion 61 flows downward in the vertical direction by the baffle plate 52, and then flows horizontally bent through the passage opening 63. The flow passage area of the passage opening 63 in the baffle plate 52 is the flow passage area when introduced into the casing 51 from the inlet 61, that is, the upstream wall 51e, the left wall 51b, and the right wall 51c. It is set larger than the flow passage area divided by the baffle plate 52. Therefore, the exhaust gas introduced into the casing 51 from the inlet 61 is not reaccelerated after passing through the passage opening 63.

In the lower part of the casing 51, the porous plate 53 is horizontally fixed so as to be parallel to the bottom 51d at a predetermined distance from the bottom 51d. The porous plate 53 is formed of a flat plate in which a large number of through holes (not shown) are formed so that exhaust gas and droplets can pass therethrough, and the middle portion in the fluid flow direction in the casing 51 Are provided up to. That is, the porous plate 53 is disposed horizontally at a predetermined height above the bottom 51 d of the casing 51 at a predetermined height in the vertical direction, and one end thereof is closely fixed to the upstream wall 51 e and Are fixed in close contact with the left wall 51b and the right wall 51c, respectively, while the other end is located at a predetermined distance from the downstream wall 51f. A reservoir 65 is formed between the porous plate 53 and the bottom 51 d of the casing 51. The storage portion 65 temporarily stores the water removed from the exhaust gas, and a drainage flow path 66 is provided in the lower portion of the casing 51.

The demister support plate 54 is located on the downstream wall 51 f side of the baffle plate 52 and the porous plate 53, and is disposed horizontally above the porous plate 53 by a predetermined height. The demister supporting plate 54 is formed of a flat plate through which exhaust gas and droplets can not pass, and one end thereof is fixed in close contact with the downstream wall 51f of the casing 51, and the left and right sides are left wall 51b. The other end portion is positioned at a predetermined distance from the baffle plate 52 while being fixed in close contact with the right wall portion 51c. Therefore, in the casing 51, a space communicating with the passage opening 63 is provided between the bottom 51d and the demister support plate 54, and this space horizontally discharges the exhaust gas flowing from the upstream channel 64. It becomes a detour flow path 67 detoured along 180 degrees. In the present embodiment, the lower end of the baffle plate 52 is located below the lower surface of the demister support plate 54 in the vertical direction.

The demister main body 55 removes mist from the exhaust gas by being disposed on the downstream side of the flow direction of the exhaust gas from the upstream side flow passage 64 and the detour flow passage 67 in the casing 51. The demister main body 55 is disposed along the vertical direction such that the inlet side faces the baffle plate 52 side. That is, in the upright state of the demister main body 55, the upper end portion is closely supported on the lower surface of the ceiling portion 51a, and the lower end portion is closely supported on the demister supporting plate 54. Although not shown, the demister main body 55 is provided with a plurality of channels which are bent a plurality of times so that the exhaust gas can pass therethrough, and is configured as a linear plate as a whole. Although one demister main body 55 is provided, a plurality of demister main bodies may be disposed.

The demister main body 55 is disposed to face the baffle plate 52, and the upstream side of the demister main body 55 is the upstream side flow path 64 and the bypass flow path 67, and the downstream side of the demister main body 55 is the downstream side flow path 68. There is. That is, the upstream side flow path 64 is configured to be separated by the upstream wall portion 51 e, the left wall portion 51 b, the right wall portion 51 c, the baffle plate 52, and the porous plate 53 of the casing 51. The bypass flow passage 67 is configured to be separated by the bottom 51 d of the casing 51, the left wall 51 b, the right wall 51 c, the downstream wall 51 f, and the demister support plate 54. The downstream flow passage 68 is configured to be separated by the ceiling 51a, the left wall 51b, the right wall 51c, the downstream wall 51f, and the demister support plate 54 of the casing 51. Therefore, the exhaust gas introduced into the casing 51 from the inlet portion 61 is bent through the upstream side flow path 64, and then horizontally turned by the detouring path 67 and detoured before reaching the demister main body 55, and the demister main body After passing through 55, the fluid is discharged from the outlet 62 through the downstream channel 68.

In the baffle plate 52, a receiving member 57 is provided on the flat portion 52a. The receiving member 57 receives droplets generated when the exhaust gas introduced into the casing 51 from the inlet portion 61 collides with the baffle plate 52. The receiving member 57 is a flat portion 52 a facing the inlet portion 61 of the baffle plate 52 and is fixed to the flat portion 52 a so as to be positioned below the inlet portion 61 in the vertical direction.

The receiving member 57 is provided along the width direction (left and right direction) on the flat portion 52a of the baffle plate 52, and extends from an intermediate position in the width direction of the baffle plate 52 toward the

wall portions

51b and 51c. And slope downward. Further, the receiving member 57 has an L-shaped cross section, so that the exhaust gas introduced into the casing 51 from the inlet portion 61 collides with the baffle plate 52 to generate droplets, and the droplets are Since it flows down along the flat portion 52a of the baffle plate 52, the receiving member 57 can receive the droplets in the groove. Then, since each end of the receiving member 57 is positioned at a predetermined distance from each of the

wall portions

51 b and 51 c, the droplet received by the groove flows downward at each end, and the storage portion 65 is dropped. Can be

In addition, although the receiving member 57 shall make L-shaped cross-sectional shape in the above-mentioned description, it is not limited to this structure. For example, the receiving member may be configured of a horizontal plate, an inclined plate, or a bent or curved plate. The receiving members 57 have left and right ends inclined downward toward the wall surfaces 51b and 51c, but only one end may incline downward to the wall surfaces 51b and 51c. Further, the receiving member 57 may be divided into a plurality of pieces, or may be arranged in a plurality of upper and lower stages. Furthermore, the receiving member 57 may be provided below the baffle plate 52 instead of the flat portion 52 a of the baffle plate 52.

Further, the demister main body 55 is provided with a projecting piece 58 which protrudes toward the bypass flow path 67 side. The projecting piece 58 is formed of a flat plate through which exhaust gas and droplets can not pass, is disposed so as to hang from the lower portion of the demister main body 55, and is fixed so as to closely contact the end of the demister supporting plate 54. ing. In the present embodiment, the demister main body 55 is constructed by assembling a plurality of flat plate members into a frame shape, and a large number of bellows plates are assembled therein, and the projecting piece 58 is a component forming the demister main body 55. For example, the end of the flat plate on the inlet side is formed to project toward the bypass flow passage 67 side. Therefore, the projecting piece 58 is disposed along the vertical direction in the same manner as the demister main body 55, so that the flat portion is disposed flush with the flat portion on the inlet side of the demister supporting plate 54 without any step. In this case, the lower end of the projecting piece 58 is positioned at the same position in the vertical direction with respect to the lower end of the baffle plate 52, or in the upper direction in the vertical direction. Therefore, the exhaust gas flowing through the upstream side flow passage 64 is guided by the projecting piece 58 so as to flow upward from the area under the demister support plate 54, that is, from the bypass flow passage 67 upward to the flat portion on the inlet side of the demister main body 55. Be done.

Hereinafter, the operation of the EGR system of the present embodiment will be described. As shown in FIG. 2, in the engine body 11, when combustion air is supplied from the scavenging air trunk 22 into the cylinder 21, the combustion air is compressed by the piston and fuel is injected to the high temperature air. It spontaneously ignites and burns. Then, the generated combustion gas is discharged from the exhaust manifold 23 to the exhaust line G2 as an exhaust gas. The exhaust gas discharged from the engine body 11 is discharged to the exhaust line G3 after rotating the turbine 32 in the turbocharger 12, and when the EGR inlet valve 41A is closed, the entire amount is discharged to the outside from the exhaust line G3. Be done.

On the other hand, when the EGR inlet valve 41A is open, a part of the exhaust gas flows from the exhaust line G3 to the exhaust gas recirculation line G4. The exhaust gas flowing into the exhaust gas recirculation line G4 is removed by the scrubber 42 from harmful substances such as contained SOx and dust. That is, when the exhaust gas passes through the venturi portion 44 at a high speed, the scrubber 42 injects water from the water injection portion 46 to cool the exhaust gas with this water, and also waters fine particles (PM) such as SOx and dust. Drop along with and remove. Then, water containing SOx, dust and the like flows into the demister unit 14 together with the EGR gas.

The exhaust gas from which harmful substances have been removed by the scrubber 42 is discharged to the exhaust gas recirculation line G5, and after the scrubber wash water is separated by the demister unit 14, the exhaust gas is sent to the turbocharger 12 by the exhaust gas recirculation line G7. Then, this exhaust gas is mixed with the air taken in from the suction line G6 to become a combustion gas, and after being compressed by the compressor 31 of the supercharger 12, it is cooled by the air cooler 48 and the engine main body 11 from the air supply line G1. Supplied to

Here, processing by the demister unit 14 will be described. As shown in FIG. 3 to FIG. 6, the exhaust gas introduced into the casing 51 from the inlet 61 collides with the flat portion 52 a of the baffle plate 52 in the front, and along the flat portion 52 a of the baffle plate 52. The spread, the contained mist becomes droplets and adheres to the flat portion 52 a of the baffle plate 52. Then, the droplets attached to the flat portion 52 a of the baffle plate 52 flow downward along the flat portion 52 a by their own weight, and are received by the receiving member 57. The droplets received by the receiving member 57 flow along the width direction of the baffle plate 52, are drained from the end to the storage portion 65, and are discharged to the outside by the drainage flow path 66.

On the other hand, the exhaust gas from which a part of the mist has been removed becomes a downward flow by the flat portion 52a of the baffle plate 52, the ceiling 51a of the casing 51, the

walls

51b and 51c, and the upstream wall 51e. Flow into The exhaust gas flowing into the upstream side channel 64 is bent by the porous plate 53 to be a horizontal flow, and is detoured while horizontally circling the bypass channel 67 by 180 degrees, and is an upward flow by the projecting piece 58 as a demister The main body 55 is reached. At this time, the exhaust gas flowing in the upstream side channel 64 passes below the baffle plate 52, but the droplets adhering to the baffle plate 52 are received by the receiving member 57 and drained to the storage portion 65. Therefore, it does not fall into the upstream channel 64. Therefore, the exhaust gas flowing through the upstream side flow path 64 is prevented from being in contact with water, and the recapture of the mist removed from the exhaust gas into the exhaust gas is suppressed.

Further, the exhaust gas flows from the bent upstream side flow passage 64 into the bypass flow passage 67 and then horizontally swirls, whereby the mist is removed by the centrifugal force. That is, since the inlet portion 61 is shifted to one side of the casing 51 (upper side in FIG. 4), the exhaust gas introduced from the shifted inlet portion 61 is guided by the baffle plate 52 and the other side of the casing 51 It becomes a horizontal flow by the upstream channel 64 while flowing to the lower side of FIG. Then, the exhaust gas flows while being guided by the left wall 51b, the downstream wall 51f, and the right wall 51c of the casing 51 so that a spiral is drawn from the other side of the casing 51 to the one side in the bypass flow path 67. Swirling flow. Since the swirling flow of the exhaust gas detours the detour flow path 67 180 degrees in the horizontal direction, the flow path of the exhaust gas in the casing 51 is extended, and the flow velocity is reduced, and the mist is easily removed by the centrifugal force. Become.

Thereafter, when the exhaust gas passes through the demister main body 55, the remaining mist condenses to form droplets, and falls into the storage portion 65. Thereafter, the exhaust gas from which the mist has been removed is discharged from the outlet 62 through the downstream flow passage 68 to the outside.

As described above, in the demister unit of the present embodiment, the casing 51 having the hollow portion to be provided with the inlet portion 61 and the outlet portion 62 of the exhaust gas, and the inlet portion 61 disposed in the casing 51 A baffle plate 52 that forms the upstream side flow passage 64 bent at a side, and a demister main body 55 disposed on the downstream side of the flow direction of the exhaust gas with respect to the upstream side flow passage 64 in the casing 51 to remove mist from the exhaust gas; The inlet portion 61 is disposed on one side in the horizontal direction from an intermediate position in the horizontal direction in the casing 51.

Therefore, the fluid introduced into the casing 51 from the inlet portion 61 is disposed so that the inlet portion 61 is shifted to one side in the horizontal direction of the casing 51. And, after flowing through the upstream side flow path 64, turn horizontally in the bypass flow path 67 and then reach the demister main body 55. As a result, the flow path of the exhaust gas becomes long and the flow velocity decreases, and while the mist removal performance can be improved, the enlargement of the casing 51 can be suppressed.

In the demister unit of this embodiment, the inlet portion 61 is disposed on one side in the horizontal direction from the middle position in the horizontal direction of the casing 51 with a half or more of the horizontal opening length of the inlet portion 61 shifted. Therefore, the exhaust gas after having collided with the baffle plate 52 can be properly turned horizontally, and the flow path of the exhaust gas can be lengthened to reduce the flow velocity of the exhaust gas.

In the demister unit of the present embodiment, the baffle plate 52 is provided so as to depend from the ceiling portion 51 a of the casing 51 to provide the passage opening 63 below, and the demister main body 55 is made from the passage opening 63 in the casing 51. By fixing on the demister supporting plate 54 fixed on the side, a detouring channel 67 is provided between the bottom 51 d of the casing 51 and the demister supporting plate 54 to communicate with the passage opening 63 to horizontally swirl the exhaust gas. There is. Therefore, the exhaust gas can be properly turned horizontally in the bypass channel 67, and the flow channel of the exhaust gas can be lengthened to reduce the flow velocity of the exhaust gas.

In the demister unit of this embodiment, the porous plate 53 is disposed at the passage opening 63 at a predetermined distance from the bottom 51d of the casing 51, and the porous plate 53 is provided up to the middle of the exhaust gas flow direction. Therefore, the bypass flow path 67 as the lower space portion of the demister support plate 54 can be expanded, and the flow path of the exhaust gas can be lengthened to reduce the flow velocity.

In the demister unit of the present embodiment, the baffle plate 52 is provided with a receiving member 57 for receiving droplets generated by collision of the exhaust gas. Therefore, the exhaust gas introduced into the casing 51 from the inlet portion 61 collides with the baffle plate 52, so that the contained mist becomes droplets and adheres to the baffle plate 52, and the flat portion 52a of the baffle plate 52 by its own weight. And is received by the receiving member 57. Therefore, the exhaust gas flowing through the upstream flow path 64 does not again take in droplets as mist, and it is possible to improve the mist removal efficiency by suppressing the reintroduction of the mist removed from the exhaust gas into the exhaust gas.

Further, in the EGR system of the present embodiment, an exhaust gas recirculation line G4 that recirculates a part of the exhaust gas discharged from the engine body 11 to the engine body as a part of the combustion gas, and an exhaust gas recirculation line G4 The scrubber 42 for removing harmful substances by injecting water to the exhaust gas flowing through and the demister unit 14 into which the exhaust gas discharged from the scrubber 42 is introduced are provided.

Therefore, in the demister unit 14, the inlet 61 is disposed on one side in the horizontal direction from the horizontal intermediate position in the casing 51, whereby the fluid introduced into the casing 51 from the inlet 61 is By colliding with the baffle plate 52, it flows to the other side in the horizontal direction, and after flowing through the upstream side channel 64, it turns horizontally in the bypass channel 67 and then reaches the demister main body 55. As a result, the flow path of the exhaust gas becomes long and the flow velocity decreases, and while the mist removal performance can be improved, the enlargement of the casing 51 can be suppressed.

In the embodiment described above, the baffle plate 52 is disposed along the vertical direction, but may be inclined.

Moreover, in embodiment mentioned above, although demonstrated using the main engine as a marine diesel engine, it is applicable also to the diesel engine used as a generator.

DESCRIPTION OF SYMBOLS 10 Marine diesel engine 11 Engine main body 12 Turbocharger 13 EGR system 14 Demister unit 41A EGR inlet valve 41B EGR outlet valve 42 Scrubber 47 EGR blower 48 Air cooler (cooler)
Reference Signs List 51 casing 52 baffle plate 53 porous plate 54 demister support plate 55 demister main body 57 receiving member 58 projecting piece 61 inlet portion 62 outlet portion 63 passage opening portion 64 upstream side flow passage (bending flow passage)
65 Reservoir 67 Detour Channel 68 Downstream Channel G4, G5, G7 Exhaust gas recirculation line G6 Intake line W1 Waste water circulation line

Claims

A casing having a hollow shape and having an inlet and an outlet for the fluid;
A baffle plate which forms a curved flow path by being disposed opposite to the inlet in the casing;
A demister main body disposed in the casing on the downstream side of the flow direction of the fluid from the bent flow passage to remove mist from the fluid;
Equipped with
The inlet portion is disposed on one side in the horizontal direction from a horizontal intermediate position in the casing.
A demister unit characterized by
The inlet portion is disposed on one side in the horizontal direction from an intermediate position in the horizontal direction in the casing at a half or more of the horizontal opening length in the inlet portion. Demista unit described.
The baffle plate is provided so as to be suspended from the ceiling of the casing so that a passage opening is provided at the lower side, and the demister main body is a demister fixed to the ceiling from the passage opening in the casing. By being fixed on the support plate, a bypass flow passage is provided between the bottom of the casing and the demister support plate so as to be in fluid communication with the passage opening to horizontally turn the fluid. The demister unit according to claim 2 or 3.
The demister unit according to claim 3, wherein a perforated plate is disposed at the passage opening at a predetermined distance from the bottom of the casing, and the perforated plate is provided up to a middle portion in the fluid flow direction.
The demister unit according to any one of claims 1 to 4, further comprising a receiving member for receiving droplets generated by the collision of the fluid with the baffle plate.
An exhaust gas recirculation line for recirculating a part of exhaust gas discharged from the engine to the engine as a combustion gas;
A scrubber for injecting a liquid to the combustion gas flowing in the exhaust gas recirculation line;
The demister unit according to any one of claims 1 to 5, wherein the combustion gas discharged from the scrubber is introduced.
An EGR system comprising: