blower

Abstract

In order to effectively suppress the adhesion and deposition of combustion residues, and corrosion caused by condensed water, an EGR blower (35) provided in a diesel engine includes a motor (80) for rotating a rotary shaft (61) inserted into a shaft hole (52a) of a casing (50), an impeller (62), and a sealing device (70) for the shaft hole (52a). The casing (50) has: a lower wall part (51) in which a suction port (51a) opens; an upper wall part (52) in which the shaft hole (52a) is formed; a suction cylinder part (53) protruding from the lower wall part (51) toward the upper wall part (52) side; a scroll-shaped peripheral wall part (55) surrounding the suction cylinder part (53); and a drain port part (56) opening to the lower wall part (51). Furthermore, a washing device (100) for washing the impeller (62) is provided, the washing device (100) having a first washing nozzle (101) for injecting washing liquid toward a back surface (62e) of the impeller (62), and a second washing nozzle (102) for injecting washing liquid to the blade surface part (62c) of the impeller (62).

Description

blower

[0001] The present invention relates to a blower, and more particularly to a blower suitable for an EGR (exhaust gas recirculation) blower that constitutes a part of an EGR system in a large or medium-sized diesel engine.

[0002] Known blowers that suck in and pressurize the gas to be blown include recirculation blowers that pressurize exhaust gas from a system that outputs power or electricity and recirculate it back into the same system, and auxiliary blowers that pressurize the gas (including low-pressure recirculated gas) supplied to the same system.

[0003] For example, one known technology for reducing exhaust emissions from marine diesel engines is an EGR system, which recirculates a portion of the engine's exhaust gas back to the scavenging side (intake side) of the engine to reduce NOx (nitrogen oxides) in the exhaust.This EGR system is equipped with an EGR blower that pressurizes a portion of the exhaust gas to a pressure that allows it to be recirculated (see, for example, Patent Document 1).

[0004] Furthermore, Patent Documents 2 and 3 describe low-pressure EGR systems for two-stroke diesel engines, which are used as the main engines of large ships, in which a portion of the low-pressure exhaust gas discharged from the engine and passing through the turbine of an exhaust turbocharger is returned as EGR gas to the air intake inlet side of the compressor of the turbocharger by an EGR blower.

[0005] In this type of low-pressure EGR system, a portion of the exhaust gas is branched off as EGR gas downstream of the turbocharger or exhaust gas economizer, and a scrubber, which is an exhaust gas cleaning device, removes PM (particulate matter) such as soot from the exhaust gas and SOx (sulfur oxides) formed in the combustion process.The cleaned EGR gas is then blown by an EGR blower at a relatively low pressure and temperature to the intake side of the turbocharger, typically to the intake port of the compressor of an exhaust turbocharger, where it is mixed with fresh air and recirculated to the engine (see Non-Patent Document 1).

[0006] Furthermore, in the case of an exhaust turbocharger, when the fuel used becomes of low quality, combustion residues in the exhaust gas adhere to the turbine of the turbocharger as dirt, and this dirt is difficult to remove. This has been noted, and Patent Document 4 describes a system in which a blind plate is placed on the outside of the exhaust inlet and a water injection cock is placed above the exhaust inlet, forming a cleaning liquid reservoir within the turbine casing in which the blade portions of the impeller in a specific rotation range can be immersed, and general use air from the ship is supplied to the air motor used to drive the impeller to rotate the impeller at a low speed, thereby removing dirt from the turbine blades.

[0007] JP 2011-157959 A JP 2018-127706 A JP 2013-170520 A JP 61-123720 A

[0008] Journal of the Japan Society of Marine Engineering, Vol. 52, No. 6 (2017)

[0009] However, conventional blowers and EGR systems equipped with the blowers as described in Patent Documents 1 to 3 cited above have had problems in that combustion residues in the exhaust gas that are not completely cleaned by the scrubber tend to adhere to and accumulate on the impeller of the EGR blower and its vicinity, and that acidic condensed water tends to adhere to the EGR path near the EGR blower, causing corrosion.

[0010] Furthermore, simply forming the EGR blower entirely from a material with excellent corrosion resistance would result in increased costs, and there is also the problem that the corrosion resistance to acidic condensed water and the like is insufficient.

[0011] In response to this, it is conceivable to remove deposits and deposits on the impeller by forming a cleaning liquid reservoir in which the impeller can be immersed and rotating the impeller at a low speed, as in the exhaust turbocharger described in Patent Document 4. However, because the cleaning agent needs to be stored to a predetermined depth, not only can the cleaning work be performed only when the engine is stopped, but problems remain in that the back surface of the impeller and the surrounding inner wall of the casing (above the cleaning liquid reservoir) cannot be properly cleaned or protected from corrosion.

[0012] The present invention has been made to solve the above-mentioned problems of the conventional art, and aims to provide an EGR blower that can effectively suppress adhesion and accumulation of combustion residues and corrosion due to condensed water inside the blower even while the engine is running.

[0013] (1) To achieve the above object, the blower of the present invention is an EGR blower that is installed as part of the EGR device in a diesel engine having an EGR device that recirculates a portion of exhaust gas discharged from an engine body as part of combustion gas, and a turbocharger driven by the exhaust gas, and that pressurizes the portion of the exhaust gas to be recirculated, and includes: a casing having a shaft hole and a gas passage having an intake port and a discharge port; a motor that rotates a drive shaft inserted into the shaft hole of the casing; an impeller supported by the drive shaft and housed within the casing; and a seal device that seals the shaft hole while slidably contacting the drive shaft. the casing has a lower wall portion where the suction port opens, an upper wall portion where the axial hole is formed, a suction tube portion that protrudes from the lower wall portion toward the upper wall portion in a truncated cone shape and whose upper end is close to the inlet portion of the impeller, a scroll-shaped peripheral wall portion that surrounds the suction tube portion and forms the gas passage, and a drain port portion that opens to the lower wall portion, and is characterized in that a cleaning device for cleaning the impeller is provided, the cleaning device having a first cleaning nozzle that sprays cleaning liquid from the upper wall portion side toward the back surface of the impeller facing the upper wall portion, and a second cleaning nozzle that sprays cleaning liquid from the peripheral wall portion side toward the blade surface portion of the impeller.

[0014] With this configuration, when the cleaning fluid is sprayed from the first and second cleaning nozzles toward the upper back surface, blade surface, and underside of the impeller, the impeller is cleaned and the cleaning fluid is drained from the drain port. Therefore, cleaning work can be performed even when the engine is running, for example, just before it is stopped, and the impeller and the surrounding inner wall of the casing can be properly cleaned. As a result, an EGR blower can be provided that can effectively suppress adhesion and accumulation of combustion residues and corrosion due to condensed water inside the EGR blower even while the engine is running.

[0015] In addition, if the impeller is integrated with the shroud, a third washing nozzle may be further provided to spray cleaning liquid from the peripheral wall or the lower wall toward the underside of the shroud of the impeller. Furthermore, by rotating the impeller during cleaning, the cleaning liquid sprayed from each washing nozzle changes speed and direction relative to the impeller, thereby enhancing the cleaning action of the impeller. Furthermore, the cleaning liquid sprayed from the second washing nozzle collides with and splashes against the impeller blade surface, thereby enhancing the cleaning effect of the impeller blade surface. Even if the cleaning liquid sprayed from the second washing nozzle reaches the inner peripheral wall surface of the suction tube from inside the impeller, the cleaning liquid can be returned to a cleaning water reservoir or water treatment device below the scrubber. Similarly, the cleaning liquid drained from the drain outlet can be returned to a cleaning water reservoir or water treatment device. Furthermore, if the motor can operate at any rotation speed and drive torque within a predetermined range, the impeller can be controlled to rotation conditions suitable for cleaning.

[0016] (2) In a preferred embodiment of the present invention, the diesel engine may be configured as a main engine of a large ship, and may also be configured as a low-pressure EGR blower that pressurizes recirculated gas in a low-pressure EGR line that recirculates a portion of exhaust gas that has passed through the turbine of the turbocharger to the compressor of the turbocharger. In this case, the EGR gas cleaned by the scrubber has a relatively low pressure and temperature, and even if acidic condensed water adheres to the EGR path near the EGR blower or combustion residue in the exhaust gas that was not completely cleaned adheres to the impeller of the EGR blower or its vicinity, the condensed water can be easily cleaned and removed together with wastewater.

[0017] (3) A preferred embodiment of the present invention may further include a mist collection unit disposed between the upper wall portion and the motor, surrounding the shaft hole and the drive shaft, and collecting mist-like leakage from the shaft hole to the atmosphere. In this case, even if cleaning fluid enters the seal of the shaft hole during cleaning inside the casing of the EGR blower, which is not normally under high pressure, and mist-like leakage from the shaft hole to the atmosphere occurs, the leakage is collected by the mist collection unit.

[0018] (4) A preferred embodiment of the present invention may be configured such that the entire inner wall surface of the casing is coated with a heat-resistant anticorrosion coating film having a glass flake layer. In this way, the glass flake layer, formed by laminating alkaline glass flakes within a heat-resistant resin coating, can have sufficient acid resistance and corrosion resistance. Furthermore, by forming the base material of the inner wall portion of the casing, which is a large component, or even the base material of the suction tube portion, from an iron-based material, costs can be reduced.

[0019] (5) In a preferred embodiment of the present invention, the seal device can include a shaft seal box that is provided in the casing to define the shaft hole and that defines an annular groove that opens onto the inner surface of the shaft hole; first seal rings and second seal rings that are each composed of a plurality of divided seal members that are biased against the drive shaft by garter springs with a predetermined contact pressure so as to surround the drive shaft within the annular groove, and at least the sliding surfaces with the drive shaft are formed of a carbon material; a ring-shaped spring support plate that is provided between the first seal ring and the second seal ring in the annular groove so as to surround the drive shaft; and a pair of toothed disc spring-shaped wire springs that are compressed between both surfaces of the spring support plate and the first seal ring and the second seal ring and bias the first seal ring and the second seal ring against both inner wall surfaces of the annular groove of the shaft seal box with a predetermined spring pressure.

[0020] In this configuration, the sliding surfaces of the first and second seal rings with garter springs are made of carbon material, providing the required corrosion resistance and self-lubricating properties. The first and second seal rings are urged against both inner wall surfaces of the annular groove in the seal box by a pair of toothed disc spring-shaped wire springs with a circular plate-shaped spring backing plate sandwiched between them. The disc springs, which have a lower spring constant than conventional disc springs, generate a stable urging force and frictional holding force against both inner wall surfaces of the annular groove. Furthermore, the pair of toothed disc spring-shaped wire springs can be shaped to be flexible not only in the axial direction of the drive shaft but also in the radial direction. This allows the pair of toothed disc spring-shaped wire springs and the circular plate-shaped spring backing plate between them to be compactly housed within the narrow seal box, while still reliably positioning them in the axial and rotational directions. This, combined with the frictional holding force on both inner wall surfaces of the annular groove, generates a positioning holding force that effectively prevents the first and second seal rings from rotating.

[0021] (6) The low-pressure EGR device for a diesel engine according to the present invention is characterized by comprising an EGR blower having the configuration described in (2) above, a wet scrubber that purifies the recirculated gas by injecting water into the low-pressure EGR line before the gas is pressurized by the low-pressure EGR blower, a demister that passes the purified recirculated gas to the low-pressure EGR blower side and separates purified wastewater from the recirculated gas, and a water treatment device with a pump that removes particulate components from the wastewater, adjusts the pH, and resupplies the wastewater to the scrubber.

[0022] With this configuration, both the cleaning liquid drained from the low-pressure EGR blower and the cleaning water drained from the wet scrubber can be introduced into the water treatment device, and by circulating them appropriately, the amount of water used can be effectively reduced.

[0023] According to the present invention, it is possible to provide an EGR blower that can effectively suppress adhesion and accumulation of combustion residues and corrosion due to condensed water inside the EGR blower even while the engine is running.

[0024] 1 is a schematic diagram showing an EGR system configuration of a low-speed diesel engine for a marine vessel including an EGR blower according to one embodiment of the present invention; 2 is a view taken in the direction of arrow II in FIG. 1, and is a front view of the EGR blower according to one embodiment of the present invention, showing a state in which a cleaning device is attached to the casing of the blower; 3 is a view taken in the direction of arrow IIIa in FIG. 2; 4 is a view taken in the direction of arrow IIIb in FIG. 3A; 5 is a view taken in the direction of arrow IV in FIG. 2; 6 is a vertical cross-sectional view of one radial side of a main part of a sealing device in an EGR blower according to one embodiment of the present invention; 7 is a plan view of a disc-shaped wire spring of a sealing device in an EGR blower according to one embodiment of the present invention, as seen in the drive shaft direction; 8 is a front view of the disc-shaped wire spring, as seen in the radial direction of the drive shaft; 9 is a plan view of an annular disk-shaped spring receiving plate of a sealing device in an EGR blower according to one embodiment of the present invention, as seen in the drive shaft direction; 10 is a plan view of a seal ring of a sealing device in an EGR blower according to one embodiment of the present invention, as seen in the drive shaft direction. FIG. 1 is a front view of the seal ring as viewed in the radial direction of the drive shaft. FIG. 2 is a plan view of a main portion of a shaft sealing box of a sealing device in an EGR blower according to one embodiment of the present invention as viewed in the drive shaft direction. FIG. 3 is a front cross-sectional view of a main portion of the shaft sealing box as viewed in the radial direction of the drive shaft. FIG. 4 is a plan view of a lid-shaped remaining portion of a shaft sealing box of a sealing device in an EGR blower according to one embodiment of the present invention as viewed in the drive shaft direction. FIG. 5 is a front cross-sectional view of a main portion of the lid-shaped remaining portion of the shaft sealing box as viewed in the radial direction of the drive shaft. FIG. 6 is a cross-sectional view of a main portion showing a division structure of an upper wall portion of a casing and an arrangement of a mist collecting unit in an EGR blower according to one embodiment of the present invention.

[0025] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0026] 1 to 11 show a blower according to an embodiment of the present invention provided as an EGR blower in a power system equipped with an EGR device.

[0027] First, the configuration will be described.

[0028] As shown in FIG. 1, the power system 1 of this embodiment includes an engine 10, which is a large two-stroke diesel engine, a turbocharger 20 (exhaust turbocharger), and a low-pressure EGR device 30, all of which are mounted in the engine room of a ship (not shown).

[0029] The engine 10 is an electronically controlled engine that can be used, for example, as the main engine of a large ship, and is a statically supercharged, low-speed diesel engine that is equipped with a multi-cylinder engine body 11 having pistons 12 and a crosshead 16, a scavenging trunk 13, an exhaust receiver 14, a fuel supply unit 15, etc. In this embodiment, the power system 1 is for use in a ship, but it can also be used for purposes other than ships, for example, as an engine for operating a large generator such as a generator at a power plant.

[0030] A multi-cylinder engine body 11 has multiple cylinders 11a (only one cylinder is shown in FIG. 1 ). Each of these multiple cylinders 11a is connected to a scavenging trunk 13 via a scavenging port 11b, and can exhaust air into an exhaust receiver 14 when the corresponding exhaust valve 14a is open. In each cylinder 11a, air taken into the cylinder 11a by scavenging is compressed by the piston 12 to above its ignition point, and fuel is injected into the air and combusted. At this time, the combustion gas expands, driving the piston 12 and generating exhaust gas. The exhaust gas from each cylinder 11a is then intermittently sent into the exhaust receiver 14.

[0031] Here, the scavenging trunk 13 serves as a compressed air reservoir (scavenging receiver) at a predetermined scavenging pressure for performing a scavenging action of discharging the combustion gas in each cylinder 11 a of the engine body 11 and filling it with new air, and the exhaust receiver 14 serves as an exhaust reservoir that accumulates and stores the exhaust gas from each cylinder 11 a of the engine body 11 while mitigating fluctuations in the exhaust pressure, and can supply the exhaust gas to the turbocharger 20 side at a stable exhaust pressure.

[0032] The fuel supply unit 15 pumps and pressurizes marine diesel fuel that has been purified by a fuel purifier, and when the fuel valve for each cylinder opens at a predetermined timing, the fuel can be injected and supplied into each cylinder 11a of the engine body 11.

[0033] The turbocharger 20 has a turbine 21 that is rotationally driven by exhaust gas supplied to the exhaust gas inlet from the exhaust receiver 14 side, and a compressor 22 that is integrally connected to the turbine 21 and rotationally driven by the turbine 21, and that introduces air from an air intake port, compresses it, and supplies it to the scavenging trunk 13 side.

[0034] Between the compressor 22 of the turbocharger 20 and the scavenging trunk 13, there is provided a heat exchange type air cooler 23 (shown as "A / C" in FIG. 1) that cools the EGR gas recirculated by the low-pressure EGR device 30 after it has been pressurized by the compressor 22. In addition, downstream of the exhaust outlet of the turbine 21 of the turbocharger 20, there is provided an economizer 25, which is a heat exchanger that recovers exhaust heat, and this economizer 25 can use the steam generated by the heat recovery for general steam for the ship, turbo power generation, etc.

[0035] The low-pressure EGR device 30 includes low-pressure EGR lines Le1 to Le3 (hereinafter simply referred to as EGR lines Le) that recirculate a portion of the relatively low-pressure, low-temperature exhaust gas that has passed through the economizer 25 as EGR gas (recirculated gas) to the air intake side of the compressor 22 of the turbocharger 20, an EGR valve 27 that is arranged near the inlet of the low-pressure EGR line Le, a wet-type scrubber 31 that purifies the EGR gas that has passed through the EGR valve 27 with cleaning droplets (for example, alkaline cleaning water), a demister 32 that separates purified wastewater from the EGR gas that has passed through the scrubber 31, and a centrifugal EGR blower 35 (low-pressure EGR blower) that takes in the low-pressure EGR gas that has passed through the demister 32 and blows it to the air intake side of the compressor 22 of the turbocharger 20.

[0036] The scrubber 31 can perform cleaning to remove PM from the EGR gas, SOx formed in the combustion process, and the like, by spraying cleaning droplets onto the EGR gas that has been taken into the low-pressure EGR line Le1, which is the recirculation path, from the smoke duct 26 side after passing through the economizer 25, and a demister 32 is provided at the bottom of the scrubber to separate and collect the droplets after the EGR gas has been purified as wastewater.

[0037] The EGR blower 35 includes a scroll-type casing 50 into which EGR gas is introduced after passing through the demister 32, a hub-shaped rotating shaft 61 (drive shaft) that is rotatably inserted through the casing 50, an impeller 62 that is supported by the rotating shaft 61 and housed within the casing 50, and a sealing device 70 that seals a shaft hole 52a (described later) while slidably contacting the outer peripheral surface of the rotating shaft 61.

[0038] As shown in Figures 1 to 4 and 11, the casing 50 has a lower wall portion 51 in which the suction port 51a opens, an upper wall portion 52 in which an axial hole 52a is formed, a suction tube portion 53 that protrudes in a truncated cone shape from the lower wall portion 51 toward the upper wall portion 52 and whose upper end 53a is close to the inlet side of the impeller 62, a scroll-shaped peripheral wall portion 55 that surrounds the suction tube portion 53 and forms the gas passage 54 as part of the EGR line Le, and a drain port portion 56 that opens into the lower wall portion 51.

[0039] The impeller 62, which is housed within the casing 50 and supported on a hub-shaped rotating shaft 61, is an integral shroud type and has a downward-facing inlet portion 62a that rotatably surrounds the protruding upper end 53a of the suction tube portion 53 at the inner end side of the gas passage 54, an outlet portion 62b that opens radially outward toward the scroll-shaped peripheral wall portion 55, a plurality of blade surface portions 62c that extend from the inlet portion 62a to the outlet portion 62b and are spaced apart at equal angular intervals from each other, a shroud 62d that covers the lower surface sides of the plurality of blade surface portions 62c, and a back surface 62e that faces the upper wall portion 52 of the casing 50.

[0040] As shown in Figures 3A and 3B, the casing 50 has a discharge port 57a (blowout port) that opens to the outer end 55a of the scroll-shaped peripheral wall portion 55, and the gas passage 54 is a scroll passage that surrounds the suction tube portion 53.

[0041] 1, a motor 80 that rotates the hub-shaped rotary shaft 61 is disposed above the casing 50. As shown in FIG. 5, the motor 80 is fastened to an annular motor mounting portion 52p that protrudes from the removable central thick plate portion 52c of the upper wall portion 52. The motor 80 has an output shaft 81 and a motor body 82 that drives the output shaft 81. The output shaft 81 is fitted inside the hub-shaped rotary shaft 61 and abuts against the rotary shaft 61 via a flinger 63, and is bolted integrally to the rotary shaft 61 with a fastening bolt and a plug-shaped washer.

[0042] Although the motor main body 82 is not shown in detail, it is an inverter-integrated electric motor controlled by, for example, a variable voltage variable frequency system (hereinafter referred to as VVVF system), and can be operated at any drive speed and drive torque within a predetermined range, so that it can be controlled to a drive state suitable for the operating conditions of the engine 10 and cleaning conditions described below. However, the motor main body 82 does not have to be an electric motor, and may be an air motor or the like.

[0043] When the impeller 62 is driven to rotate by the output shaft 81 of the motor 80 via the hub-shaped rotating shaft 61 within the casing 50, the EGR gas introduced into the gas passage 54 after being cleaned on the scrubber 31 side is blown into the air intake of the compressor 22 of the turbocharger 20, pressurized by the compressor 22 so as to be able to be scavenged, and recirculated to the engine 10 via the air cooler 23.

[0044] 2, a cleaning device 100 for cleaning the impeller 62 and the inner wall 58 of the casing 50 in the vicinity thereof is attached to the casing 50. The cleaning device 100 has a first cleaning nozzle 101 that sprays cleaning liquid from the upper wall 52 side toward the back surface 62e of the impeller 62 facing the upper wall 52, a second cleaning nozzle 102 that sprays cleaning liquid from the peripheral wall 55 side toward the blade surface 62c of the impeller 62, and a third cleaning nozzle 103 that sprays cleaning liquid from the peripheral wall 55 or the lower wall 51 side toward the underside of the shroud 62d of the impeller 62. The cleaning device 100 further has a cleaning liquid distribution pipe 104 that has one end as a collecting pipe connected to a cleaning liquid supply source (e.g., a pump 36 and a water treatment device 37 described below) and the other end as a three-branch pipe, and a valve 105 provided at one end of the cleaning liquid distribution pipe 104.

[0045] The first cleaning nozzle 101 can spray cleaning liquid from above near the radial position of the outer periphery of the impeller 62 at an inclination angle θ1 toward the vertically upward direction with respect to the back surface 62e of the impeller 62 and in a spray direction D1 toward the center of the impeller 62. The spray flow rate can be adjusted by a valve 105 incorporating a spherical valve body or the like. The spray direction D1 of the cleaning liquid from the first cleaning nozzle 101 may be set to be inclined toward the circumferential direction of the impeller 62 at a predetermined intersecting angle with the radial direction of the back surface 62e. In this case, the cleaning liquid can be sprayed in a direction deviating from the hub-shaped rotating shaft 61, and the relative speed of the cleaning liquid at the collision point with the rotation of the impeller 62 can also be adjusted. The spray strength of the cleaning liquid can be changed, for example, by the valve 105 or the pump 36, or by an additional spray control valve or booster pump. The temperature of the sprayed cleaning liquid can be changed by switching the cleaning liquid supply means or by utilizing steam heat. Furthermore, the spraying of the cleaning liquid is not limited to the spraying of only liquid, but can also be the spraying of a mixed fluid of liquid and gas, pressurized superheated steam, etc., and the spray form can be one or more fan-shaped, conical, or other jet forms.

[0046] The second cleaning nozzle 102 is disposed so as to be located outside the outer periphery of the impeller 62 near the installation height of the blade surface portion 62c in the direction of the rotation axis of the impeller 62, and is inclined at a predetermined angle at least in the circumferential direction with respect to the blade surface portion 62c of the impeller 62, and is configured to spray the cleaning liquid in a spray direction D2 toward the center of the impeller 62. The spray flow rate of the second cleaning nozzle 102 can be adjusted by a valve 105 and is changed at a constant rate relative to the spray flow rate of the first cleaning nozzle 101. Note that although the spray direction D2 of the cleaning liquid from the second cleaning nozzle 102 is illustrated as a spray direction close to the horizontal direction, it may be set to be inclined at an angle in the vertical direction toward the rotation axis of the impeller 62 to enhance the cleaning effect depending on the shape of the blade surface portion 62c.

[0047] The third cleaning nozzle 103 can spray cleaning liquid from outside the outer circumferential radius of the impeller 62 at a predetermined inclination angle at least in the vertical direction with respect to the underside of the shroud 62d of the impeller 62, in a spray direction D3 toward the center of the impeller 62. The spray flow rate of the third cleaning nozzle 103 can be adjusted by a valve 105, and is changed at a substantially constant rate with respect to the spray flow rates of the first cleaning nozzle 101 and the second cleaning nozzle 102. Note that although the spray direction D3 of the cleaning liquid from the third cleaning nozzle 103 is illustrated as a spray direction inclined at least vertically upward (to one side in the rotational axis direction of the impeller 62), it goes without saying that the spray direction D3 can also be set to be inclined in the circumferential direction of the impeller 62 to enhance the cleaning effect, depending on the shape of the shroud 62d.

[0048] The cleaning device 100 is disposed on the small-radius region side of the scroll-shaped peripheral wall portion 55 of the casing 50, and the drain outlet portion 56 is disposed close to the large-radius region side of the scroll-shaped peripheral wall portion 55. That is, the cleaning liquid sprayed from each of the first cleaning nozzle 101, the second cleaning nozzle 102, and the third cleaning nozzle 103 flows downward while being scattered or forced in the centrifugal direction by the rotation of the impeller 62 in the air blowing direction, and is then drained to the drain outlet portion 56. A drain pipe (not shown) is connected to the drain outlet portion 56, and the cleaning liquid can be returned through the drain pipe to a cleaning water reservoir below the scrubber 31 or the demister 32, the water treatment device 37, or the like. Note that, to facilitate drainage from the drain outlet portion 56, the lower wall portion 51 may be slightly inclined from the horizontal plane so that the drain outlet portion 56 side is lower.

[0049] As shown in Figure 5, the hub-shaped rotating shaft 61 is a cylindrical body with a lid that can be connected to the output shaft 81 of the motor 80 so as to rotate integrally with it, and has a stepped approximately cylindrical body 61a that fits onto the output shaft 81 of the motor 80 with a predetermined fitting pressure, a plug-shaped washer 61b that fits concentrically onto one end of the approximately cylindrical body 61a inside the impeller 62 and closes that one end, an annular spacer 61c that can position the approximately cylindrical body 61a and the plug-shaped washer 61b relative to the output shaft 81 of the motor 80, a bolt 61d that fastens and fixes the approximately cylindrical body 61a, the plug-shaped washer 61b, and the spacer 61c integrally to the output shaft 81 of the motor 80, and a rotation-preventing pin 61e.

[0050] As shown in Figures 5 to 9A and 9B, the sealing device 70 includes a shaft seal box 71 that forms an annular groove 71h that opens onto the inner surface of the shaft hole 52a, a first seal ring 73A and a second seal ring 73B that are housed in the annular groove 71h, a ring-shaped spring support plate 74 that is provided between the first and second seal rings 73A and 73B in the annular groove 71h so as to surround the hub-shaped rotating shaft 61, and a pair of toothed disc spring-shaped wire springs 75A and 75B that are compressed between both surfaces of the spring support plate 74 and the first and second seal rings 73A and 73B and urge the first and second seal rings 73A and 73B against both inner wall surfaces of the annular groove 71h of the shaft seal box 71 with a predetermined spring pressure.

[0051] As shown in Figures 5, 9A, 9B, 10A, and 10B, the shaft seal box 71 is composed of a box main body 71A and a circular plate-shaped side plate 71B that is integrally fastened to the box main body 71A by a plurality of side plate mounting screws 76, and the box main body 71A and the side plate 71B form the shaft hole 52a and the annular groove 71h.

[0052] As shown in Figures 9A and 9B, the box body 71A has a circular recess 71v that opens on one side that will face the impeller 62 after installation, a circular center hole 71a that penetrates the inner portion of the circular recess 71v, a flange 71f located on the opening end side of the circular recess 71v, multiple side plate mounting holes 71g, multiple fixing bolt holes 71hb, and an anti-rotation pin mounting hole 71ia.

[0053] As shown in Figures 10A and 10B, the annular side plate 71B has a circular center hole 71b with the same inner diameter as the circular center hole 71a of the box main body 71A, and a plurality of mounting screw holes 71ha formed at the same radial positions and at the same angular intervals as the plurality of side plate mounting holes 71g so that a plurality of side plate mounting screws 76 can be inserted and screwed into the plurality of side plate mounting holes 71g of the box main body 71A, and an anti-rotation pin mounting hole 71ib.

[0054] The shaft seal box 71, which is composed of a box main body 71A and a circular plate-shaped side plate 71B, is fastened together with a plurality of side plate mounting screws 76, with each circular center hole 71a, 71b positioned so that they are located on the same central axis.

[0055] The shaft seal box 71 is fastened integrally to the central thick plate portion 52c of the upper wall portion 52 with a gasket 78 sandwiched therebetween by inserting a plurality of fixing bolts 77 into a plurality of fixing bolt holes 71hb formed in the flange 71f of the box body 71A and screwing them into the central thick plate portion 52c of the upper wall portion 52. When fastened, the box body 71A and the annular side plate 71B are arranged and positioned so that the circular center holes 71a, 71b are positioned on the central rotation axis C1 of the hub-shaped rotating shaft 61 and the output shaft 81 of the motor 80.

[0056] In addition, the circular central thick plate portion 52c of the upper wall portion 52 is formed with a larger diameter than the impeller 62, and by removing the central thick plate portion 52c by removing the multiple mounting bolts 52b from the outer peripheral portion of the upper wall portion 52 of the casing 50, it is possible to separate the rotating portion from the motor 80 to the impeller 62 from the fixed portion including the remainder of the casing 50.

[0057] As shown in Figures 5 and 8A and 8B, the first and second seal rings 73A and 73B are each composed of a plurality of two-piece divided seal members 73sa and 73sb that are biased against the hub-shaped rotating shaft 61 with a predetermined contact pressure by a garter spring 72 so as to surround the hub-shaped rotating shaft 61 within the annular groove 71h, and at least the sliding surfaces of both divided seal members 73sa and 73sb that come into contact with the hub-shaped rotating shaft 61 are formed of a carbon material.

[0058] As shown in Figures 5, 9A, 9B, 10A, and 10B, the first and second seal rings 73A and 73B are provided with a plurality of anti-rotation pins 71pa and 71pb that protrude parallel to the central axis of rotation C1 from both inner wall surfaces Fs1 and Fs2 (see Figures 9A, 9B, 10A, and 10B) of the annular groove 71h of the shaft seal box 71.

[0059] These multiple anti-rotation pins 71pa, 71pb are engaged with the first and second seal rings 73A, 73B in the axial direction of the hub-shaped rotary shaft 61 in a concave-convex manner.

[0060] As shown in Figures 5 and 6A and 6B, each of the pair of toothed disc spring-shaped wire springs 75A, 75B has a plurality of arc portions 75r extending in the circumferential direction, a plurality of inner convex claw portions 75c, and both end portions 75e1, 75e2 bent into a cantilever hook shape, and has a free shape in which both end portions 75e1, 75e2 are spaced apart in the circumferential direction by a predetermined gap d.

[0061] In addition, a pair of toothed disc spring-shaped wire springs 75A, 75B are bent to a radially reduced state so as to be pressed against the innermost surface 71c of the annular groove 71h (see Figures 5, 9A, and 9B), and are fitted into the shaft seal box 71.In this fitted state, the multiple inner convex claw portions 75c are spaced apart from each other at approximately equal angular intervals, so that the entire circumferential area of ​​the first and second seal rings 73A, 73B is biased with uniform lateral pressure.

[0062] 5 and 7, the annular spring receiving plate 74 has a plurality of through holes 74h and arc-shaped notches 74n formed at equal intervals, and the notches 74n allow adjustment of the angular position in the circumferential direction of the annular spring receiving plate 74. For example, the notches 74n are positioned so that they can be seen from an inspection hole 110 with an open / close lid located on the front side of the casing 50 when the blower is installed.

[0063] In addition, the radial gap on the inner diameter side of the annular plate-shaped spring support plate 74 relative to the hub-shaped rotating shaft 61 is larger than the radial gap on the outer diameter side of the annular plate-shaped spring support plate 74 relative to the innermost surface 71c of the annular groove 71h, and the dimensions are set so that the annular plate-shaped spring support plate 74 does not come into contact with the hub-shaped rotating shaft 61.

[0064] Furthermore, a mist collection unit 90 is provided between the upper wall portion 52 and the motor 80, which surrounds the shaft hole 52a and the hub-shaped rotating shaft 61 from the radially outward side and collects mist-like leakage that leaks from the shaft hole 52a into the atmosphere.

[0065] This mist collection unit 90 has an annular protrusion 91 that protrudes from the upper wall portion 52 to the height of the motor mounting reference plane Mt so as to surround the shaft hole 52a and the hub-shaped rotating shaft 61 and is close to the mounting plate 83 of the motor 80, and a plurality of filter-like mist catchers 92 that are arranged at equal angular intervals on the annular protrusion 91, so that it can collect mist-like leakage that leaks from the shaft hole 52a to the atmosphere through the sliding gap between the sealing device 70 and the hub-shaped rotating shaft 61.

[0066] 2, a heat-resistant anticorrosion coating 58i is applied to the entire inner wall 58 of the casing 50. The anticorrosion coating 58i has glass flake layers 58f arranged in multiple layers within a heat-resistant or thermosetting paint resin coating 58r. The glass flake layers 58f are formed by spraying alkaline glass flakes, for example, so that they are uniformly dispersed throughout the paint resin coating and laminated in multiple layers. This allows the anticorrosion coating 58i to function as an acid-resistant, heat-resistant lining.

[0067] A heat-resistant anticorrosion coating 58i is also applied to an inner peripheral wall surface 53b and an outer peripheral wall surface 53c of the suction tube portion 53 of the casing 50. In other words, the entire inner wall 58 of the casing 50 referred to here means the entire gas passage 54 formed as part of the EGR line Le within the casing 50, and may include the inner peripheral wall surface 53b of the suction tube portion 53 and the anticorrosion coating 57i on the inner wall of the outlet tube portion 57 that forms the discharge port 57a.

[0068] The entire inner wall 58 of the casing 50 coated with the anticorrosive coating 58i, including the lower wall 51, upper wall 52, suction tube 53, and peripheral wall 55, is made of an iron-based material, such as a general structural rolled steel. On the other hand, the hub-shaped rotating shaft 61 (including the bolt 61d and plug-shaped washer 61b) and the impeller 62 are each made of, for example, stainless steel, which has excellent strength and corrosion resistance.

[0069] In this way, in this embodiment, the diesel engine 10 is configured as the main engine of a large ship, and an EGR blower is provided in the low-pressure EGR line Le, which recirculates a portion of the exhaust gas that has passed through the turbine 21 of the turbocharger 20 to the compressor 22 of the turbocharger 20, and blows the recirculated gas in the low-pressure EGR line Le while increasing the pressure of the recirculated gas to the supply pressure to the compressor 22.

[0070] Next, the operation will be described.

[0071] In the EGR blower 35 of this embodiment and the low-pressure EGR device 30 including the same, which are configured as described above, the casing 50 has a suction tube 53 that protrudes from the lower wall 51 in a truncated cone shape and has an upper end 53a that is inserted into and close to the inlet 62a of the impeller 62, a scroll-shaped peripheral wall 55 that surrounds the suction tube 53 and forms a gas passage 54, and a drain port 56 that opens into the lower wall 51. Therefore, when cleaning liquid is sprayed from the first to third cleaning nozzles 101 to 103 toward the back surface 62e, blade surface 62c, and underside of the shroud 62s of the impeller 62, the impeller 62 is cleaned and the cleaning liquid is drained from the drain port 56. Therefore, cleaning work can be performed even when the engine 10 is operating, for example, immediately before it is stopped, and the impeller 62 and the inner wall 58 of the casing 50 around it can be accurately cleaned. As a result, adhesion and accumulation of combustion residues and corrosion due to condensed water inside the EGR blower 35 can be effectively suppressed even while the engine 10 is running.

[0072] In addition, when the impeller 62 is rotated in the air blowing direction during cleaning, the cleaning liquid sprayed from the first and third cleaning nozzles 101, 103 undergoes a change in speed relative to the impeller 62 and a change in direction in the centrifugal direction, thereby enhancing the cleaning action of the impeller 62, and the cleaning liquid sprayed from the second cleaning nozzle 102 collides with the blade surface portion 62c of the impeller 62 and scatters, thereby enhancing the cleaning effect of the blade surface portion 62c of the impeller 62.

[0073] Furthermore, even if the cleaning liquid sprayed from the second cleaning nozzle 102 reaches the inner peripheral wall surface 53b of the suction tube 53 from inside the impeller 62, the cleaning liquid can be returned to the cleaning water reservoir below the scrubber 31 or demister 32, or to the water treatment device 37, etc., and the cleaning liquid drained from the drain outlet 56 can also be returned to the cleaning water reservoir or to the water treatment device 37, etc. Furthermore, since the VVVF type motor 80 can operate at any rotation speed and drive torque within a predetermined range, the impeller 62 can be controlled to rotation conditions suitable for cleaning.

[0074] The blower of this embodiment functions as an EGR blower 35 and pressurizes the recirculated gas in the low-pressure EGR line Le. Therefore, even if the EGR gas cleaned by the scrubber 31 is at a relatively low pressure and temperature, and acidic condensed water adheres to the EGR path Le near the EGR blower 35, or combustion residues in the exhaust gas that were not completely cleaned adhere to the impeller 62 of the EGR blower 35 or its vicinity, they can be easily cleaned and removed together with the wastewater.

[0075] Furthermore, in this embodiment, a mist collection unit 90 that collects mist-like leakage that leaks from the shaft hole 52a into the atmosphere is provided between the upper wall portion 52 and the motor 80.Therefore, even if the cleaning liquid enters the seal portion of the shaft hole 52a during cleaning inside the casing 50 of the EGR blower 35, which is not normally under very high pressure, and mist-like leakage occurs that leaks from the shaft hole 52a into the atmosphere, the leakage is reliably collected by the mist collection unit 90.

[0076] In this embodiment, the entire inner wall 58 of the casing 50 is coated with a heat-resistant anticorrosive coating 58i having a glass flake layer 58f, thereby providing sufficient acid resistance and corrosion resistance. Furthermore, by forming the base material 58s of the inner wall portion that forms the inner wall 58 of the casing 50, which is a large component (the base material 51s of the lower wall portion 51 in the enlarged partial view of FIG. 2), or further the base material of the suction tube portion 53, from an iron-based material, it is possible to reduce costs.

[0077] Furthermore, in this embodiment, at least the inner sliding surfaces of the first and second seal rings 73A, 73B with garter springs in the seal device 70 are made of a carbon material, thereby achieving the required corrosion resistance and self-lubricating properties. Furthermore, the first and second seal rings 73A, 73B are biased against both inner wall surfaces (Fs1 and Fs2 in FIGS. 9A and 9B and 10A and 10B ) of the annular groove 71 h of the shaft seal box 71 by a pair of toothed disc spring-shaped wire springs 75A, 75B sandwiching the annular plate-shaped spring backing plate 74 therebetween. Therefore, the toothed disc spring-shaped wire springs 75A, 75B, which have a lower spring constant than ordinary disc springs, can generate a stable biasing force and frictional holding force on the first and second seal rings 73A, 73B against both inner wall surfaces of the annular groove 71 h.

[0078] Furthermore, the pair of toothed disc spring-shaped wire springs 75A, 75B are shaped so that they can flex not only in the axial direction of the hub-shaped rotating shaft 61 but also in the radial direction. Therefore, the pair of toothed disc spring-shaped wire springs 75A, 75B and the annular plate-shaped spring support plate 74 between the two springs can be compactly stored within the narrow shaft seal box 71, while being reliably positioned in the axial and rotational directions. This, combined with the frictional holding force on both inner wall sides of the annular groove 71h and the anti-rotation force of the anti-rotation pins 71pa, 71pb, generates a positioning holding force that effectively prevents the first and second seal rings 73A, 73B from rotating.

[0079] In addition, the low-pressure EGR device 30 of the marine diesel engine 10 of this embodiment is equipped with a wet scrubber 31 that purifies EGR gas by injecting water in the low-pressure EGR line Le before the EGR gas is boosted by the EGR blower 35, a demister 32 that passes the purified EGR gas toward the EGR blower 35 and separates purified wastewater from the gas, and a water treatment device 37 with a pump that removes particulate components from the wastewater, adjusts the pH, and resupplies it to the scrubber.Therefore, both the cleaning solution discharged from the EGR blower 35 and the cleaning water discharged from the wet scrubber 31 can be introduced into the water treatment device 37, and by circulating them appropriately, the amount of water used can be effectively reduced.

[0080] In this manner, in this embodiment, adhesion and accumulation of combustion residues and corrosion due to condensed water inside the EGR blower 35 can be effectively suppressed even while the engine 10 is running.

[0081] In the EGR blower 35 according to the embodiment described above, the output shaft 81 of the motor 80 is inserted into the hub-shaped rotating shaft 61 and the two are integrated by bolting, but the connection form between the impeller 62 and the motor 80 is not particularly limited as long as it can be driven to rotate.

[0082] In the above-described embodiment, the cleaning agent sprayed from the first to third cleaning nozzles 101 to 103 mainly cleans the impeller 62, which is made of a specific stainless steel material with particularly excellent corrosion resistance, and only the vicinity of the impeller 62 is cleaned by the cleaning liquid spray on the inner wall 58 of the casing 50. However, the cleaning range can be appropriately set depending on the tendency of dirt adhesion and accumulation. Also, the spray direction of the cleaning liquid is inclined mainly toward the rotational center axis C1 of the impeller 62. However, for example, the first to third cleaning nozzles 101 to 103 may have spray ports facing different directions, so that a wider range of the inner wall 58 can be cleaned. Furthermore, it is also possible to offset the effect on the rotation of the impeller 62, or to spray the cleaning agent to add force or resistance to the rotational direction.

[0083] Furthermore, in one embodiment, the engine 10 is for use in a ship, but the present invention can also be applied to large engines other than those for ships, such as stationary engines for operating generators.

[0084] As described above, the present invention provides an EGR blower that can effectively suppress adhesion and accumulation of combustion residues and corrosion due to condensed water inside the blower even while the engine is running, and is useful for all EGR blowers that form part of the EGR device in large or medium-sized diesel engines.

[0085] DESCRIPTION OF SYMBOLS 1 Power system 10 Engine (diesel engine, marine diesel engine, main engine) 11 Engine body (internal combustion engine body) 11a Cylinder 11b Scavenging port 12 Piston 13 Scavenging trunk (scavenging air receiver) 14 Exhaust receiver (exhaust gas reservoir) 14a Exhaust valve 15 Fuel supply unit 16 Crosshead 20 Turbocharger (exhaust gas turbocharger) 21 Turbine 22 Compressor 23 Air cooler 25 Economizer 26 Flue duct 27 EGR valve 30 Low-pressure EGR device 31 Scrubber (wet scrubber) 32 Demister 35 EGR blower (low-pressure EGR blower) 37 Water treatment device 50 Casing 51 Lower wall portion 51a Intake port 52 Upper wall portion 52a Shaft hole 52b a plurality of mounting bolts 52c central thick plate portion 53 suction tube portion 53a upper end 53b inner peripheral wall surface 53c outer peripheral wall surface 54 gas passage 55 peripheral wall portion (peripheral wall portion on scroll) 55a outer end portion 56 drain port portion 57 blowout tube portion 57a ​​discharge port (blowout port) 57i, 58i corrosion-resistant coating film 58 inner wall (inner wall surface portion) 58f glass flake layer 58r coating film 61 rotating shaft (drive shaft) 61a approximately cylindrical body 61b washer 61c spacer 61d bolt 62 impeller 62a inlet portion 62b outlet portion 62c blade surface portion 62d shroud 62e back surface (upper back surface) 62s shroud (covering the lower side of the blade surface portion) 63 Flinger 70 Sealing device 71 Shaft seal box 71A Box body 71B Side plate 71a, 71b Center hole 71c Inner inner surface 71f Flange 71g Side plate mounting hole 71h Annular groove 71ha Mounting screw hole 71hb Fixing bolt hole 71ia, 71ib Anti-rotation pin mounting hole 71pa, 71pb Anti-rotation pin 71v Circular recess 72 Garter spring 73A First seal ring 73B Second seal ring 73sa, 73sb Divided seal member 74 Spring receiving plate 74h Through hole 74n Notch 75A, 75B Wire spring (toothed disc spring-shaped wire spring) 75c Inner convex claw portion 75e1,75e2 Both ends 75r Arc portion 76 Side plate mounting screw 77 Fixing bolt 80 Motor 81 Output shaft (drive shaft) 82 Motor body 83 Mounting plate 90 Mist collection unit 91 Annular convex portion 92 Mist catcher 100 Cleaning device 101 First cleaning nozzle (rear surface cleaning nozzle) 102 Second cleaning nozzle (wing cleaning nozzle) 103 Third cleaning nozzle (underside cleaning nozzle) 104 Cleaning liquid distribution pipe 105 Valve 110 Inspection hole C1 Rotation center axis D1, D2, D3 Spray direction (spray direction of cleaning liquid) Fs1, Fs2 Inner wall surface Le, Le1, Le2, Le3 Low-pressure EGR line (exhaust gas recirculation path) Mt Motor mounting reference plane θ1 Inclination angle

Claims

1. An EGR blower is provided as part of an EGR device for a diesel engine having an EGR device for recirculating a portion of exhaust gas discharged from an engine body as a portion of a combustion gas, and a turbocharger driven by the exhaust gas, and pressurizes a portion of the exhaust gas to be recirculated, the EGR blower comprising: a casing having a shaft hole and a gas passage having an intake port and a discharge port; a motor for rotating a drive shaft inserted into the shaft hole of the casing; an impeller supported by the drive shaft and housed within the casing; and a sealing device for sealing the shaft hole while in slidable contact with the drive shaft, the casing having a lower wall portion where the intake port opens, an upper wall portion where the shaft hole is formed, a suction tube portion protruding from the lower wall portion toward the upper wall portion in a truncated cone shape and having an upper end adjacent to the inlet portion of the impeller, a scroll-shaped peripheral wall portion surrounding the suction tube portion and forming the gas passage, and a drain port portion opening into the lower wall portion, an EGR blower characterized in that a cleaning device for cleaning the impeller is provided, the cleaning device having a first cleaning nozzle that sprays cleaning liquid from the upper wall portion side toward a back surface of the impeller facing the upper wall portion, and a second cleaning nozzle that sprays cleaning liquid from the peripheral wall portion side toward a blade surface portion of the impeller.

2. The EGR blower according to claim 1, characterized in that the diesel engine is configured as the main engine of a large ship and is also configured as a low-pressure EGR blower that pressurizes the recirculated gas in a low-pressure EGR line that recirculates a portion of the exhaust gas that has passed through the turbine of the turbocharger to the compressor of the turbocharger.

3. An EGR blower as described in claim 1 or 2, further comprising a mist collection unit disposed between the upper wall portion and the motor, surrounding the shaft hole and the drive shaft, and collecting mist-like leakage that leaks from the shaft hole into the atmosphere.

4. The EGR blower according to claim 1 or 2, characterized in that the entire inner wall surface of the casing is coated with a heat-resistant anticorrosive coating having a glass flake layer.

5. The EGR blower as claimed in claim 1 or 2, characterized in that the sealing device comprises: a shaft seal box provided to define the shaft hole in the casing and forming an annular groove opening onto the inner peripheral surface of the shaft hole; a first seal ring and a second seal ring each composed of a plurality of divided seal members urged against the drive shaft by garter springs with a predetermined contact pressure so as to surround the drive shaft within the annular groove, the first seal ring and the second seal ring having at least a sliding surface formed of a carbon material; a ring-shaped spring support plate provided between the first seal ring and the second seal ring in the annular groove so as to surround the drive shaft; and a pair of toothed disc spring-shaped wire springs compressed between both sides of the spring support plate and the first seal ring and the second seal ring for urging the first seal ring and the second seal ring against both inner wall surfaces of the annular groove of the shaft seal box with a predetermined spring pressure.

6. A low pressure EGR system for a diesel engine comprising the EGR blower as defined in claim 2, a wet type scrubber which purifies the recirculated gas by injecting water into the low pressure EGR line before the gas is pressurized by the low pressure EGR blower, a demister which passes the purified recirculated gas to the low pressure EGR blower side and separates purified wastewater from the recirculated gas, and a water treatment device with a pump which removes particulate components from the wastewater, adjusts the pH and resupplies the wastewater to the scrubber.

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