blower

Abstract

To provide an EGR blower capable of effectively suppressing adhesion and accumulation of combustion residues and corrosion caused by condensation water, etc. within the blower even during an operation of an engine.SOLUTION: An EGR blower mounted to a diesel engine having an EGR device includes: a motor 80 for rotating a rotating shaft 61 inserted into a shaft hole of a casing 50; an impeller 62; and a sealing device 70 for the shaft hole. The casing 50 includes: a lower wall part 51 on which a suction port is opened; an upper wall part 52 on which the shaft hole is formed; a suction cylinder part 53 projecting 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; and a water discharge port part 56 opened on the lower wall part 51. The blower further includes a cleaning device 100 that has a first cleaning nozzle 101 for injecting cleaning fluid toward a back surface 62e of the impeller 62 and a second cleaning nozzle 102 for injecting the cleaning fluid from the peripheral wall part 55 side to a blade surface part 62c of the impeller 62, and cleans the impeller 62.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Known types of 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 to the same system, and auxiliary blowers that pressurize the gas (including low-pressure recirculated gas) supplied to the same system.

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

[0004] Furthermore, in a two-stroke diesel engine that is used as the main engine of a large ship, Patent Documents 2 and 3 describe a low-pressure EGR system 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 PM (particulate matter) such as soot in the exhaust gas and SOx (sulfur oxides) formed in the combustion process are removed by a scrubber, which is an exhaust gas cleaning device.The cleaned EGR gas is then blown by an EGR blower to the intake side of the turbocharger, typically the intake port of the compressor of an exhaust turbocharger, at a relatively low pressure and temperature, 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 to form a cleaning liquid reservoir inside the turbine casing in which the blade portions of the impeller in a specific rotational section 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. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2011-157959 A [Patent Document 2] JP 2018-127706 A [Patent Document 3] JP 2013-170520 A [Patent Document 4] Japanese Patent Publication No. 123720 / 1983 [Non-patent literature]

[0008] [Non-Patent Document 1] Journal of the Japan Society of Marine Engineering, Vol. 52, No. 6 (2017) Summary of the Invention [Problem to be solved by the invention]

[0009] However, conventional blowers and EGR systems equipped with the blowers as described in the above-mentioned Patent Documents 1 to 3 have problems in that combustion residues in the exhaust gas that cannot be completely washed away 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 high costs, and there is still the problem that the corrosion resistance to acidic condensed water and the like is insufficient.

[0011] In response to this, it is conceivable to form a cleaning liquid reservoir in which the impeller can be immersed and remove adhesions and deposits on the impeller by rotating the impeller at a low speed, as in the exhaust turbocharger described in Patent Document 4. However, since it is necessary to accumulate the cleaning agent to a certain 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 adequately cleaned or protected from corrosion.

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

[0013] (1) In order to achieve the above object, a blower according to the present invention is an EGR blower that is installed as a part of the EGR device in a diesel engine having an EGR device that recirculates a part of exhaust gas discharged from an engine body as a part of combustion gas, and a turbocharger driven by the exhaust gas, and that pressurizes a part of the exhaust gas to be recirculated, the blower comprising: 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 shaft hole is formed, a suction tube portion protruding from the lower wall portion toward the upper wall portion in a truncated cone shape with an upper end close 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, and the casing 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, in the present invention, when the cleaning liquid is sprayed from the first and second cleaning nozzles toward the upper back surface, the blade surface, and the lower surface of the impeller, the impeller is cleaned and the cleaning liquid is drained from the drain port. Therefore, even when the engine is in operation, for example, just before it is stopped, the cleaning operation can be performed and the impeller and the inner wall of the casing around it can be cleaned properly. As a result, an EGR blower is provided that can effectively suppress adhesion and accumulation of combustion residues and corrosion due to condensed water in the EGR blower even while the engine is in operation.

[0015] In addition, when the impeller is integrated with the shroud, a third washing nozzle may be further provided to inject a washing liquid from the peripheral wall or the lower wall toward the underside of the shroud of the impeller. In addition, when the impeller is rotated during washing, the washing liquid injected from each washing nozzle changes its speed relative to the impeller and its direction in the centrifugal direction, thereby enhancing the washing action of the impeller, and the washing liquid injected from the second washing nozzle collides with the blade surface of the impeller and scatters, thereby enhancing the washing effect of the blade surface of the impeller. In addition, even if the washing liquid injected from the second washing nozzle reaches the inner peripheral wall surface of the suction tube from inside the impeller, the washing liquid can be returned to a washing water reservoir or water treatment device below the scrubber, and the washing liquid drained from the drain can be returned to a washing water reservoir or water treatment device. In addition, if the motor can operate at any rotation speed and drive torque within a predetermined range, the impeller can be controlled to a rotation condition suitable for washing.

[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 for increasing the pressure of 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. In this case, even if the EGR gas cleaned by the scrubber has a relatively low pressure and temperature and acidic condensed water adheres to the EGR path near the EGR blower, or combustion residues in the exhaust gas that have not been completely cleaned adhere to the impeller of the EGR blower or its vicinity, they can be easily cleaned and removed together with wastewater.

[0017] (3) A preferred embodiment of the present invention may further include a mist collecting unit that is provided between the upper wall portion and the motor to surround the shaft hole and the drive shaft and collect mist-like leakage from the shaft hole to the atmosphere. In this case, even if the cleaning liquid enters the seal of the shaft hole during cleaning inside the casing of the EGR blower, which is usually not under high pressure, and mist-like leakage occurs from the shaft hole to the atmosphere, the leakage is collected by the mist collecting 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 anticorrosive coating having a glass flake layer. In this way, the glass flake layer formed by laminating glass flakes of an alkaline component in a coating of a heat-resistant paint resin can have sufficient acid resistance and corrosion resistance. In addition, the base material of the inner wall portion of the casing, which is a large part, or even the base material of the suction tube portion, can be made of an iron-based material, thereby reducing costs.

[0019] (5) In a preferred embodiment of the present invention, the seal device can be configured to include: a shaft seal box provided to define the shaft hole in the casing and forming an annular groove opening onto an 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 biased against the drive shaft by a garter spring 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 faces of the spring support plate and the first seal ring and the second seal ring for biasing 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 way, the sliding surfaces of the first and second seal rings with garter springs are made of carbon material, so that the required corrosion resistance and self-lubrication can be obtained, and the first and second seal rings are biased against both inner wall surfaces of the annular groove of the shaft seal box by a pair of toothed disc spring-shaped wire springs with a ring-shaped spring support plate sandwiched between them, so that the disc spring-shaped wire springs, which have a lower spring constant than a normal disc spring, can generate a stable biasing force and frictional holding force against both inner wall surfaces of the annular groove in the first and second seal rings. In addition, the pair of toothed disc spring-shaped wire springs can be shaped so that they can be deflected not only in the axial direction of the drive shaft but also in the radial direction, so that the pair of toothed disc spring-shaped wire springs and the ring-shaped spring support plate between the two springs can be compactly stored in the narrow shaft seal box, and they can be reliably positioned in the axial and rotational directions, and a positioning holding force that effectively prevents the first and second seal rings from rotating can be generated in combination with the frictional holding force on both inner wall sides of the annular groove.

[0021] (6) The low-pressure EGR device of the diesel engine according to the present invention is characterized in that it comprises an EGR blower having the configuration described in (2) above, a wet-type scrubber that purifies the recirculated gas by injecting water in 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 re-supplies 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. Effect of the Invention

[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. [Brief description of the drawings]

[0024] [Figure 1] 1 is a schematic diagram showing an EGR system configuration of a low-speed marine diesel engine including an EGR blower according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 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 a casing of the blower. [Diagram 3] 3A is a view seen in the direction of arrow IIIa in FIG. 2, and FIG. 3B is a view seen in the direction of arrow IIIb in FIG. [Figure 4] 4 is a view taken in the direction of arrow IV in FIG. 2. [Diagram 5] 2 is a vertical cross-sectional view of a main part of the sealing device in the EGR blower according to the embodiment of the present invention, taken on one radial side. FIG. [Figure 6] FIG. 2A is a plan view of a disc spring-shaped wire spring of a sealing device in an EGR blower according to one embodiment of the present invention, as viewed in the drive shaft direction, and FIG. 2B is a front view of the disc spring-shaped wire spring as viewed in the radial direction of the drive shaft. [Figure 7] FIG. 2 is a plan view of a ring-shaped spring support plate of a sealing device in an EGR blower according to one embodiment of the present invention, as viewed in the drive shaft direction. [Figure 8] FIG. 2A 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 viewed in the drive shaft direction, and FIG. 2B is a front view of the seal ring as viewed in the radial direction of the drive shaft. [Figure 9] FIG. 1A is a plan view of a main part of a shaft seal box of a sealing device in an EGR blower according to one embodiment of the present invention, as viewed in the drive shaft direction, and FIG. 1B is a front cross-sectional view of the main part of the shaft seal box, as viewed in the radial direction of the drive shaft. [Figure 10] FIG. 1A is a plan view of the lid-shaped remaining part of a shaft seal box of a sealing device in an EGR blower according to one embodiment of the present invention, as viewed in the drive shaft direction, and FIG. 1B is a front cross-sectional view of the lid-shaped remaining part of the shaft seal box, as viewed in the drive shaft radial direction. [Figure 11] 3 is a cross-sectional view of a main part 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. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 static pressure supercharged low-speed diesel engine in which a scavenging trunk 13, an exhaust receiver 14, a fuel supply unit 15, etc. are attached to a multi-cylinder engine body 11 having pistons 12 and a crosshead 16. Note that, although the power system 1 is for use on ships in this embodiment, 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 is provided with a plurality of cylinders 11a (only one cylinder is shown in FIG. 1). Each of the cylinders 11a is connected to a scavenging trunk 13 via a scavenging port 11b, and can exhaust 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 the ignition point, and fuel is injected into the air and combusted. At this time, the combustion gas expands to drive the piston 12 and generate exhaust gas. Then, the exhaust gas from each cylinder 11a is 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 11a of the engine body 11 while filling it with new air, and the exhaust receiver 14 serves as an exhaust reservoir that can accumulate and store the exhaust gas from each cylinder 11a of the engine body 11 while mitigating the exhaust pressure fluctuations and 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 is capable of injecting and supplying the fuel into each cylinder 11a of the engine body 11 when the fuel valve for each cylinder opens at a predetermined timing.

[0033] The turbocharger 20 has a turbine 21 that is rotationally driven by exhaust gas supplied to an exhaust 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 an air cooler 23 (shown as "A / C" in FIG. 1) of a heat exchange type that cools the EGR gas recirculated by the low-pressure EGR device 30 after it is 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 is capable of using steam generated by 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 and 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 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 (e.g., 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 of the compressor 22 of the turbocharger 20.

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

[0037] The EGR blower 35 includes a scroll-type casing 50 into which the EGR gas after passing through the demister 32 is introduced, 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 being in slidable contact with the outer circumferential 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 into which an intake port 51a opens, an upper wall portion 52 in which a shaft hole 52a is formed, an intake tube portion 53 which protrudes from the lower wall portion 51 toward the upper wall portion 52 in a truncated cone shape with an upper end 53a close to the inlet side of the impeller 62, a scroll-shaped peripheral wall portion 55 which surrounds the intake tube portion 53 and forms the gas passage 54 as part of the EGR line Le, and a drain port portion 56 which 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 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 side 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 3(a) and 3(b), the casing 50 has a discharge port 57a (blow-out port) that opens to the outer end portion 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 rotating shaft 61 is disposed above the casing 50. As shown in FIG. 5, the motor 80 is fastened to an annular motor attachment 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 into the hub-shaped rotating shaft 61 and abuts against the rotating shaft 61 via a flinger 63, and is bolted integrally to the rotating shaft 61 by a fastening bolt and a plug-shaped washer.

[0042] Although the motor body 82 is not shown in detail, it is, for example, an inverter-integrated electric motor controlled by a variable voltage variable frequency method (hereinafter referred to as the VVVF method), 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 later. However, the motor body 82 need not be an electric motor, and may be an air motor or the like.

[0043] When the impeller 62 is rotated by the output shaft 81 of the motor 80 via the hub-shaped rotating shaft 61 inside the casing 50, the EGR gas introduced into the gas passage 54 after cleaning 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 scavenged, and recirculated to the engine 10 via the air cooler 23.

[0044] 2, the casing 50 is fitted with a cleaning device 100 for cleaning the impeller 62 and the inner wall 58 of the casing 50 in the vicinity thereof, and the cleaning device 100 has a first cleaning nozzle 101 for spraying a 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 for spraying a cleaning liquid from the peripheral wall 55 side toward the blade surface 62c of the impeller 62, and a third cleaning nozzle 103 for spraying a 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 having one end connected to a cleaning liquid supply source (for example, a pump 36 and a water treatment device 37 described later) as a collecting pipe and the other end as three branch pipes, and a valve 105 provided at one end of the cleaning liquid distribution pipe 104.

[0045] The first cleaning nozzle 101 can spray the cleaning liquid from above near the radial position of the outer periphery of the impeller 62 at an inclination angle θ1 vertically upward with respect to the back surface 62e of the impeller 62 and in a spray direction D1 toward the center of the impeller 62, and 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 crossing angle with respect to the radial direction of the back surface 62e. In that case, the cleaning liquid can be sprayed in a direction deviating from the hub-shaped rotating shaft 61, and the relative speed at the collision site of the cleaning liquid with respect to 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 a booster pump, and the temperature of the spray of the cleaning liquid can be changed by switching the supply means of the cleaning liquid or by using steam heat, etc. Furthermore, the spraying of the cleaning liquid is not limited to the spraying of only liquid, but may be a mixed fluid of liquid and gas, pressurized superheated steam, etc., and the spray form may 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 rotation axis direction of the impeller 62, and is configured to form a predetermined inclination angle at least in the circumferential direction with respect to the blade surface portion 62c of the impeller 62, and to spray the cleaning liquid in a spray direction D2 toward the center side of the impeller 62. The spray flow rate of the second cleaning nozzle 102 can be adjusted by a valve 105, and is configured to change at a constant ratio 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 in the vertical direction toward the rotation axis direction of the impeller 62 so as to enhance the cleaning effect according to the shape of the blade surface portion 62c.

[0047] The third cleaning nozzle 103 can spray cleaning liquid from the outer side of the outer circumferential radius of the impeller 62 at a predetermined inclination angle at least in the vertical direction with respect to the lower surface of the shroud 62d of the impeller 62, and 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 ratio to the spray flow rates of the first cleaning nozzle 101 and the second cleaning nozzle 102. In addition, 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), but it can of course be set to also be inclined in the circumferential direction of the impeller 62 so as 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 port portion 56 is disposed close to the major radius region side of the scroll-shaped peripheral wall portion 55. That is, the cleaning liquid sprayed from the first cleaning nozzle 101, the second cleaning nozzle 102, and the third cleaning nozzle 103 respectively flows down while being scattered or forced in the centrifugal direction by the rotation of the impeller 62 in the blowing direction, and is drained to the drain port portion 56. A drain pipe (not shown) is connected to the drain port 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, or to the water treatment device 37, etc. Note that, in order to facilitate drainage from the drain port portion 56, the lower wall portion 51 may be slightly inclined from the horizontal plane so that the drain port portion 56 side is lower.

[0049] As shown in FIG. 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 therewith, 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 into 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-prevention pin 61e.

[0050] As shown in Figures 5 to 9, the sealing device 70 includes a shaft seal box 71 forming an annular groove 71h that opens onto the inner circumferential surface of the shaft hole 52a, a first seal ring 73A and a second seal ring 73B housed in the annular groove 71h, a ring-shaped spring support plate 74 provided between the first and second seal rings 73A, 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, 75B that are compressed between both sides of the spring support plate 74 and the first and second seal rings 73A, 73B and urge the first and second seal rings 73A, 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, 9 and 10, the shaft seal box 71 is composed of a box main body 71A and a circular ring-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 Figure 9, the box body 71A has a circular recess 71v that opens onto one side that will face the impeller 62 after installation, a circular central 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, a plurality of side plate mounting holes 71g, a plurality of fixing bolt holes 71hb, and an anti-rotation pin mounting hole 71ia.

[0053] As shown in FIG. 10, the annular side plate 71B has a circular center hole 71b having the same inner diameter as the circular center hole 71a of the box body 71A, and a plurality of mounting screw holes 71ha and anti-rotation pin mounting hole 71ib formed at the same radial position 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 therethrough to screw the side plate 71B into the plurality of side plate mounting holes 71g of the box body 71A.

[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 by a plurality of side plate mounting screws 76 with their respective circular central holes 71a, 71b positioned 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 a 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 rotation center 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 multiple mounting bolts 52b from the outer circumferential portion of the upper wall portion 52 of the casing 50 and detaching the central thick plate portion 52c, 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 8, the first and second seal rings 73A, 73B are each composed of a plurality of two-piece split seal members 73sa, 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 split seal members 73sa, 73sb that contact the hub-shaped rotating shaft 61 are formed from a carbon material.

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

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

[0060] As shown in Figures 5 and 6, a pair of toothed disc spring-like wire springs 75A, 75B each have 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 have 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-like wire springs 75A, 75B are bent into a radially reduced state so as to be pressed against the innermost surface 71c of the annular groove 71h (see Figures 5 and 9), 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 side pressure.

[0062] 5 and 7, the annular spring support 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 circumferential angular position of the annular spring support plate 74. For example, the notches 74n are positioned so that they can be seen from an inspection hole 110 with an openable lid that is 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 material leaking out 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 number of filter-like mist catchers 92 arranged at equal angular intervals on the annular protrusion 91, and is capable of collecting mist-like leakage material 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 anticorrosive coating 58i is applied over the entire inner wall 58 of the casing 50, and the anticorrosive coating 58i has glass flake layers 58f arranged in multiple layers in 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 the glass flakes are evenly dispersed in the paint resin coating and layered in multiple layers, and the anticorrosive coating 58i functions as a heat-resistant lining having acid resistance.

[0067] Further, a heat-resistant anticorrosive 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. That is, the entire inner wall 58 of the casing 50 referred to here means the entire gas passage 54 formed as a part of the EGR line Le inside the casing 50, and may include the inner peripheral wall surface 53b of the suction tube portion 53 and the anticorrosive coating 57i on the inner wall of the outlet tube portion 57 forming the discharge port 57a.

[0068] In the entire inner wall 58 of the casing 50 on which the anticorrosive coating film 58i is applied, the base materials of the lower wall portion 51, the upper wall portion 52, the suction cylinder portion 53, the peripheral wall portion 55, etc. of the casing 50 are made of an iron-based material, for example, a rolled steel material for general construction. On the other hand, the hub-shaped rotating shaft 61 (including the bolt 61d and the plug-shaped washer 61b) and the impeller 62 are each made of, for example, stainless steel having excellent strength and corrosion resistance.

[0069] As described above, in this embodiment, the diesel engine 10 is configured as the main engine of a large ship, and an EGR blower is provided in a 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, to blow air while boosting the recirculated gas in the low-pressure EGR line Le to the supply pressure to the compressor 22.

[0070] Next, the operation will be described.

[0071] In the EGR blower 35 of the present embodiment and the low-pressure EGR device 30 including the EGR blower 35 configured as described above, the casing 50 has a suction tube 53 protruding from the lower wall 51 in a truncated cone shape with an upper end 53a inserted into and adjacent to the inlet 62a of the impeller 62, a scroll-shaped peripheral wall 55 surrounding the suction tube 53 to form a gas passage 54, and a drain port 56 opening into the lower wall 51. When the cleaning liquid is sprayed from the first to third cleaning nozzles 101 to 103 toward the back surface 62e, the blade surface 62c, and the lower surface of the shroud 62s of the impeller 62, the impeller 62 is cleaned and the cleaning liquid after cleaning is drained from the drain port 56. Therefore, even when the engine 10 is in an operating state, for example, immediately before it is stopped, the cleaning operation can be performed, and the impeller 62 and the inner wall 58 of the casing 50 around it can be cleaned appropriately. 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 in operation.

[0072] In addition, by rotating the impeller 62 in the air blowing direction during cleaning, the cleaning liquid sprayed from the first and third cleaning nozzles 101, 103 changes in speed relative to the impeller 62 and changes 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 splashes, 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 portion 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 portion 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 the EGR blower 35 and boosts 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, these 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 material leaking from the shaft hole 52a to 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 normally not under much pressure, and mist-like leakage material leaks from the shaft hole 52a to the atmosphere, the leakage material is reliably collected by the mist collection unit 90.

[0076] In this embodiment, the heat-resistant anticorrosive coating 58i having the glass flake layer 58f is applied to the entire area of ​​the inner wall 58 of the casing 50, so that sufficient acid resistance and corrosion resistance can be provided. Also, the base material 58s of the inner wall portion forming the inner wall 58 of the casing 50, which is a large part (base material 51s of the lower wall portion 51 in the partially enlarged view in FIG. 2), or further the base material of the suction tube portion 53, can be made of an iron-based material, thereby reducing costs.

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

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

[0079] In addition, the low-pressure EGR device 30 of the marine diesel engine 10 of this embodiment is equipped with a wet-type scrubber 31 that purifies the EGR gas before it is boosted by the EGR blower 35 in the low-pressure EGR line Le by injecting water, a demister 32 that passes the purified EGR gas to the EGR blower 35 side 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 re-supplies it to the scrubber. Therefore, both the cleaning solution discharged from the EGR blower 35 and the cleaning water discharged from the wet-type scrubber 31 can be introduced into the water treatment device 37, and by appropriately circulating them, 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 in operation.

[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 rotated.

[0082] In the above embodiment, the impeller 62 made of a specific stainless steel material having particularly excellent corrosion resistance is mainly cleaned by the cleaning agent jet from the first to third cleaning nozzles 101 to 103, and only the vicinity of the impeller 62 is cleaned by the cleaning liquid jet of the inner wall 58 of the casing 50. However, the cleaning range can be appropriately set according to the tendency of adhesion and accumulation of dirt. In addition, the jet direction of the cleaning liquid is inclined mainly toward the rotation center axis C1 of the impeller 62, but for example, the first to third cleaning nozzles 101 to 103 may have jet ports facing different directions, so that a wide range of the inner wall 58 can be cleaned. Furthermore, it is also possible to cancel the influence on the rotation of the impeller 62, or to jet the cleaning agent to add or resist the rotation direction.

[0083] Furthermore, in the embodiment, the engine 10 is for 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 can provide an EGR blower that can effectively suppress the adhesion and accumulation of combustion residues inside the blower and corrosion due to condensed water 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. [Explanation of symbols]

[0085] 1. Power System 10 Engines (diesel engines, marine diesel engines, main engines) 11 Engine body (internal combustion engine body) 11a Cylinder 11b Scavenging port 12 Piston 13 Scavenging trunk (scavenging air receiver) 14 Exhaust receiver 14a Exhaust valve 15 Fuel supply unit 16 Crosshead 20 Turbocharger (exhaust turbocharger) 21 Turbine 22 Compressor 23 Air Cooler 25 Economizer 26 Smoke path 27 EGR valve 30 Low pressure EGR device 31 Scrubber (wet scrubber) 32 Demistar 35 EGR blower (low pressure EGR blower) 37 Water Treatment Equipment 50 Casing 51 Lower wall part 51a Intake port 52 Upper wall 52a Shaft hole 52b Multiple mounting bolts 52c Center plank section 53 Suction tube 53a top end 53b Inner wall surface 53c Outer wall 54 Gas passage 55 Peripheral wall portion (peripheral wall portion on scroll) 55a Outer end 56 Drain port 57 Blowout cylinder part 57a Discharge port (air outlet) 57i, 58i Anticorrosive coating 58 Inner wall (inner wall surface part) 58f Glass flake layer 58r paint film 61 Rotating shaft (drive shaft) 61a Approximately cylindrical body 61b Washer 61c Spacer 61d Bolt 62 Impeller 62a Entrance 62b Exit section 62c Wing surface section 62d Shroud 62e Rear (upper rear) 62s Shroud (underside cover of wing surface) 63 Flinga 70 Sealing device 71 Shaft seal box 71A Box body 71B Side plate 71a, 71b center hole 71c Inner surface 71f flange 71g Side plate mounting hole 71h Circular groove 71ha Mounting screw hole 71hb Fixing bolt hole 71ia, 71ib Lock pin mounting hole 71pa, 71pb rotation stop pin 71v Circular recess 72 Garter Springs 73A First Seal Ring 73B Second seal ring 73sa, 73sb split seal member 74 Spring support plate 74h through hole 74n Notch 75A, 75B Wire springs (toothed disc spring-shaped wire springs) 75c Inner convex claw part 75e1, 75e2 both ends 75r arc section 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 Circular protrusion 92 Mist Catcher 100 Cleaning equipment 101 First cleaning nozzle (rear cleaning nozzle) 102 Second cleaning nozzle (wing cleaning nozzle) 103 3rd cleaning nozzle (lower surface cleaning nozzle) 104 Cleaning solution distribution pipe 105 Valve 110 Inspection hole C1 Rotational axis D1, D2, D3 Spray direction (cleaning solution spray direction) Fs1, Fs2 inner wall Le, Le1, Le2, Le3 Low pressure EGR line (exhaust gas recirculation path) Mt Motor mounting reference surface θ1 Tilt angle

Claims

1. An EGR blower is provided in a diesel engine including an EGR device that recirculates 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, the EGR blower being provided as a part of the EGR device and pressurizing a portion of the exhaust gas to be recirculated, a casing having an axial hole and a gas passage having a suction port and a discharge port; a motor that rotates a drive shaft that is inserted through the shaft hole of the casing; The impeller is supported by the drive shaft and accommodated in the casing, and a seal device is configured to seal 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 shaft 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 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 diesel engine is configured as a main engine of a large ship, 2. The EGR blower according to claim 1, which is 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 a turbine of the turbocharger to a compressor of the turbocharger.

3. 3. The EGR blower according to claim 1, further comprising a mist collecting unit provided 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. 3. The EGR blower according to claim 1, wherein an entire inner wall surface of the casing is coated with a heat-resistant anticorrosive coating having a glass flake layer.

5. The sealing device comprises: a shaft seal box provided in the casing to define the shaft hole and having an annular groove that opens onto an inner peripheral surface of the shaft hole; a first seal ring and a second seal ring each of which is composed of a plurality of divided seal members biased against the drive shaft by a garter spring at a predetermined contact pressure so as to surround the drive shaft in the annular groove, and at least a sliding surface thereof that comes into contact with the drive shaft is made of a carbon material; a spring support plate having an annular plate shape provided between the first seal ring and the second seal ring in the annular groove so as to surround the drive shaft; 3. The EGR blower according to claim 1, further comprising a pair of toothed disc spring-shaped wire springs that are compressed between both sides of the spring support plate and the first and second seal rings, and that urge the first and second seal rings against both inner wall surfaces of the annular groove of the shaft seal box with a predetermined spring pressure.

6. The EGR blower according to claim 2, 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 the purified wastewater from the recirculated gas; a water treatment device equipped with a pump that removes particulate components from the wastewater, adjusts the pH of the wastewater, and resupplies the water to the scrubber.

Images