Marine turbocharger

Abstract

To provide a detergent improved in washing effect on removal of dirt adhering to a turbine impeller, and also to provide a marine supercharger.SOLUTION: A detergent CL used for washing a turbine impeller 4 of a marine supercharger 1 contains hydroxyethyl iminodiacetic acid or 2-hydroxy-1,3-diaminopropane tetraacetic acid. The marine supercharger 1 includes: the turbine impeller 4 which rotates by receiving exhaust gas discharged from a combustor of a marine internal combustion engine; a turbine housing 2; an exhaust pipe 3 which leads the exhaust gas discharged from the combustor to the inside of the turbine housing 2; a detergent tank 5 which accommodates the detergent CL; and a detergent pipe 6 which passes the detergent CL from the detergent tank 5 to the exhaust pipe 3. A wall part 3a of the exhaust pipe 3 has an injection port 7 which is in communication with an open end 6a of the discharge side of the detergent pipe 6 for injecting the detergent CL into the exhaust pipe 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a marine turbocharger. [Background technology]

[0002] In gas turbines, which are internal combustion engines that include blades, dirt can accumulate on the surfaces of turbine blades during operation. The accumulation of such dirt is undesirable, as it can cause the turbine to rotate unstably. In response to this issue, Patent Document 1 discloses a technology related to a cleaning fluid that is injected into the inlet side of the turbine compressor section, located upstream of the combustor, primarily to clean the turbine compressor section.

[0003] On the other hand, in marine turbochargers that are installed on marine internal combustion engines that use heavy oil as fuel and that include blades similar to gas turbines, solidified fouling, mainly consisting of combustion residues, can adhere to the surface of the turbine impeller during operation.In order to remove such fouling from the turbine impeller, conventionally, cleaning has been performed by directly pouring water onto the turbine impeller during operation of the marine turbocharger, and immersion cleaning has been performed during maintenance of the marine turbocharger. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2003-515666 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when removing dirt adhering to the turbine impeller of a marine turbocharger, a cleaning effect that is greater than that achieved by conventional water injection cleaning or immersion cleaning is desired.

[0006] On the other hand, when cleaning the turbine impeller of a marine turbocharger, it is also conceivable to use a cleaning agent such as that disclosed in Patent Document 1. However, when the fuel for a marine internal combustion engine is, for example, heavy oil, the components of the dirt adhering to the turbine impeller depend on the heavy oil, and therefore, using a conventional cleaning agent does not necessarily lead to an improvement in the cleaning effect.

[0007] Therefore, an object of the present disclosure is to provide a marine turbocharger that uses a detergent that improves the cleaning effect when removing dirt adhering to a turbine impeller. [Means for solving the problem]

[0008] A marine turbocharger according to one aspect of the present disclosure includes: a turbine impeller that rotates upon receiving exhaust gas discharged from a combustor of a marine internal combustion engine that uses C heavy oil as fuel; a turbine housing that has the turbine impeller disposed therein; an exhaust pipe that is connected to an exhaust gas inlet provided in the turbine housing and that introduces the exhaust gas discharged from the combustor into the inside of the turbine housing; a cleaning agent tank that stores a cleaning agent used to clean the turbine impeller; and a cleaning agent piping that distributes the cleaning agent from the cleaning agent tank to the exhaust pipe, wherein a wall of the exhaust pipe has an inlet that communicates with an open end on the discharge side of the cleaning agent piping and that injects the cleaning agent into the exhaust pipe, and the cleaning agent contains 2-hydroxy-1,3-diaminopropanetetraacetic acid.

[0009] In the above marine turbocharger, in a range downstream of the inlet in the exhaust pipe, the angle formed by the axial direction of the exhaust pipe at the position where the inlet is provided and the axial direction of the open end on the discharge side of the cleaning agent piping may be an acute angle.

[0010] The cleaning agent may also contain glycerin. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a marine turbocharger that uses a detergent that improves the cleaning effect when removing dirt adhering to a turbine impeller. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a configuration of a marine turbocharger according to one embodiment. FIG. [Figure 2] 1 is a graph showing the evaluation results of the temperature dependency of the cleaning effect in the first test. [Figure 3] 1 is a graph showing the evaluation results of the time dependency of the cleaning effect in the first test. [Figure 4] 10 is a graph showing the evaluation results regarding cleaning performance in the second test. [Figure 5] 10 is a graph showing the evaluation results of spreadability in the third test. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a marine turbocharger according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, several exemplary embodiments will be described with reference to the drawings, etc. Hereinafter, the dimensions, materials, and other specific numerical values ​​shown in each embodiment are merely examples and do not limit the present disclosure unless otherwise specified. Furthermore, elements having substantially the same functions and configurations are assigned the same reference numerals to avoid redundant explanation, and elements not directly related to the present disclosure are not shown in the drawings.

[0014] Fig. 1 is a schematic diagram showing the configuration of a marine turbocharger 1 according to one embodiment. For example, a marine internal combustion engine such as a marine diesel engine is used as a drive source for sailing a ship. The marine turbocharger 1 is a device that is installed in such a marine internal combustion engine and resupplies compressed air generated using exhaust gas emitted from the marine internal combustion engine in order to improve engine performance and fuel efficiency.

[0015] The marine turbocharger 1 first includes a turbine housing 2, an exhaust pipe 3, a turbine impeller 4, a compressor (not shown), a cleaning agent tank 5, and a cleaning agent piping 6.

[0016] The turbine housing 2 accommodates a turbine impeller 4. The turbine housing 2 has an inlet 2a for introducing exhaust gas discharged from a combustor of a marine internal combustion engine (not shown), and an outlet 2b for discharging the exhaust gas from the inside to the outside.

[0017] The exhaust pipe 3 is connected to the inlet 2a and introduces the exhaust gas discharged from the combustor into the turbine housing 2. In FIG. 1, the direction in which the exhaust gas is introduced is indicated by a white arrow. In this embodiment, there is only one exhaust pipe 3, which is depicted as a straight pipe in FIG. 1. However, the exhaust pipe 3 may also be a curved pipe.

[0018] The turbine impeller 4 rotates upon receiving exhaust gas introduced into the turbine housing 2 via the exhaust pipe 3. Specifically, the turbine impeller 4 is a disk-shaped rotating body on which a plurality of blades are formed. A rotating shaft (not shown) is coaxially connected to the turbine impeller 4.

[0019] The compressor generates compressed air by utilizing the rotational force transmitted from the turbine impeller 4. The compressor includes a compressor housing and a compressor impeller. The compressor housing has the compressor impeller disposed therein. The compressor housing has an air inlet for introducing air from the outside and a compressed air outlet for discharging the compressed air generated inside toward the combustor of the marine internal combustion engine. A silencer may be installed at the air inlet. The compressor impeller is specifically a disk-shaped rotating body having multiple blades. The above-mentioned rotating shaft is coaxially connected to the compressor impeller from the opposite side to the turbine impeller 4. The compressor impeller rotates when the turbine impeller 4 rotates after receiving exhaust gas, thereby compressing the air introduced into the compressor housing.

[0020] The cleaning agent tank 5 stores the cleaning agent CL used to clean the turbine impeller 4. The cleaning agent CL employed in this embodiment will be described in detail below.

[0021] The cleaning agent pipe 6 distributes the cleaning agent CL from the cleaning agent tank 5 to the exhaust pipe 3. An open end on the inlet side of the cleaning agent pipe 6 is connected to a supply port (not shown) of the cleaning agent tank 5. Meanwhile, a wall portion 3a of the exhaust pipe 3 has an injection port 7 through which the cleaning agent CL is injected into the exhaust pipe 3. An open end 6a on the discharge side of the cleaning agent pipe 6 communicates with the injection port 7. In this embodiment, as an example, two injection ports 7 are formed in the wall portion 3a of the exhaust pipe 3. The two injection ports 7 are located on the same cross section of the exhaust pipe 3 and face each other. In this case, the cleaning agent pipe 6 is one pipe on the upstream side connected to the cleaning agent tank 5, and branches midway so as to have two pipes on the downstream side connected to the two injection ports 7.

[0022] The cleaning agent pipe 6 may be provided with, for example, a first valve 10, a second valve 12, a pressure gauge 14, and a pressure adjustment valve 16. The first valve 10 is provided in each of the two branched cleaning agent pipes 6, and can, for example, individually adjust whether or not to inject the cleaning agent CL from each injection port 7, or the injection amount of the cleaning agent CL to be injected into the exhaust pipe 3. The second valve 12 is provided in the cleaning agent pipe 6 before branching, near the cleaning agent tank 5, and, for example, switches between whether or not to inject the cleaning agent CL. The second valve 12 is opened when cleaning is performed by injecting the cleaning agent CL, and is closed when cleaning using the cleaning agent CL is not performed. The operator can adjust the injection amount of the cleaning agent CL by adjusting the pressure with the pressure adjustment valve 16 while checking the value indicated by the pressure gauge 14.

[0023] Furthermore, downstream of the inlet 7 in the exhaust pipe 3, the angle θ formed between the axial direction of the exhaust pipe 3 at the position where the inlet 7 is provided and the axial direction of the cleaning agent pipe 6 at the discharge-side open end 6a may be an acute angle. Here, the axial direction of the exhaust pipe 3 refers to the direction extending parallel to the central axis AX1 of the exhaust pipe 3. On the other hand, the axial direction of the cleaning agent pipe 6 refers to the direction extending parallel to the central axis AX2 of the cleaning agent pipe 6. Note that although the inlet 7 in this embodiment has a cut-off shape, the inlet 7 may also be provided with an orifice, a sprayer, or the like.

[0024] Next, a description will be given of the cleaning agent CL that can be employed in the marine turbocharger 1 and is used to clean the turbine impeller 4. Here, in order to identify the cleaning agent CL that is suitable for cleaning the turbine impeller 4, the following test was carried out.

[0025] First, a first test was conducted to identify the components of the chelating agent to be contained in cleaning agent CL. In the first test, artificial foulants that are assumed to adhere to the surface of the turbine impeller 4 due to continuous operation of the marine turbocharger 1 were selected in advance, and the cleaning performance against the selected artificial foulants was evaluated. In particular, the evaluation of cleaning performance here was an evaluation of the temperature dependency of the cleaning effect and an evaluation of the time dependency of the cleaning effect.

[0026] In the first test, four chelating agents A to D were selected as samples. The components of each of the chelating agents A to D, as well as the concentration and pH of the sample solutions, are shown in Table 1. Purified water was used for dilution. The concentration of the sample solution for chelating agent B was the only value obtained by adjusting it to a 10-fold diluted solution.

[0027] [Table 1]

[0028] For the first test method, first, various sample solutions (chelating agent aqueous solutions) are prepared by diluting chelating agents A to D as shown in Table 1. Next, weighed simulated soil (approximately 0.5 g) is placed in a 30 ml screw-top test tube. Next, 10 ml of the sample solution is added to the test tube and shaken. Next, the test tube is left to stand at a specified temperature or for a specified period of time. However, during the period of standing, shaking is performed every 24 hours. After the specified period has elapsed, the contents of the test tube are filtered using a weighed 1 μm membrane filter, and the filtrate is dried and weighed. The remaining proportion (%) of simulated soil is then calculated from the weight of the filtrate.

[0029] In the first test, two types of reagents were selected as simulated soiling materials, and each was evaluated. The first reagent was calcium sulfate dihydrate (CaSO4 2H2O) (98%, particle size: ~100 μm). The second reagent was vanadium pentoxide reagent (VO5) (99%, particle size: ~100 μm). In this case, if the marine internal combustion engine is a marine diesel engine fueled by heavy oil C (Japanese Industrial Standards: JIS K 2205; heavy oil type 3), the soiling adhering to the surface of the turbine impeller 4 will primarily consist of inorganic fuel residues such as calcium sulfate and vanadium pentoxide. In other words, the reagents used in the first test were selected to resemble the components of actual soiling materials.

[0030] Figure 2 is a graph showing the evaluation results of the temperature dependence of cleaning effectiveness in the first test. Figure 2(a) shows the results when the artificial soil is calcium sulfate. Figure 2(b) shows the results when the artificial soil is vanadium pentoxide. Note that both evaluations also include the results when purified water (pH 5.7) was used instead of the chelating agent for comparison. Here, the test temperatures [°C] on the horizontal axis are 25 (room temperature), 50, and 100°C, and the immersion time (test time) is 72 hours. Because the chelating agent solubilizes the artificial soil in the aqueous solution, the smaller the soil remaining rate [wt%] after the test on the vertical axis, the better the cleaning performance.

[0031] 2(a), when the artificial soil is calcium sulfate, all of the various sample solutions have better cleaning properties than purified water. Furthermore, these results show that among these chelating agents A to C, chelating agent C has better cleaning properties.

[0032] Referring to FIG. 2(b), when the pseudo-foulant is vanadium pentoxide, chelating agent B has the best cleaning performance at a temperature of 25°C. However, with chelating agent B, the dirt remaining rate increases sharply as the temperature increases. This is presumably because, when chelating agent B is used, weight increase and solidification of the pseudo-foulant (change from powder to solid) were confirmed at a temperature of 100°C, and vanadium salts were formed. In particular, considering that cleaning using cleaning agent CL may be performed during operation of the marine turbocharger 1, a decrease in cleaning performance at high temperatures is undesirable. Therefore, it is difficult to adopt chelating agent B as the chelating agent to be contained in cleaning agent CL. On the other hand, it can be seen that the cleaning performance of chelating agent C is good among chelating agents A to D, as in the case when the pseudo-foulant is calcium sulfate.

[0033] Figure 3 is a graph showing the results of the evaluation of the time dependence of the cleaning effect in the first test. Figure 3(a) shows the results when the artificial soil was calcium sulfate. Figure 3(b) shows the results when the artificial soil was vanadium pentoxide. Again, both evaluations include the results when purified water was used instead of the chelating agent for comparison. Here, the immersion time (test time) [hours] on the horizontal axis is 1, 3, 6, 24, 48, and 72 hours, and the test temperature is 25°C (room temperature).

[0034] 3(a) and 3(b), it can be seen that the cleaning properties of chelating agents B and C are better than those of chelating agent A or purified water. Regarding chelating agent C, regardless of whether the artificial soil is calcium sulfate or vanadium pentoxide, the amount of dissolved artificial soil reaches saturation after an immersion time of 1 hour. In other words, it is believed that chelating agent C is more effective at removing soil than chelating agent B, regardless of whether the artificial soil is calcium sulfate or vanadium pentoxide, as long as the immersion time is within the range of 1 to 3 hours.

[0035] Thus, the evaluation of the first test, obtained by comparing preselected chelating agents A to D, shows that the chelating agent that is desirable to include in cleaning agent CL is chelating agent C, which contains hydroxyethyliminodiacetic acid.

[0036] Next, a second test was conducted to identify the ingredients of the chelating agent to be contained in the detergent CL. In the second test, calcium sulfate and vanadium pentoxide were selected as simulated soils in advance, as in the first test, and the cleaning performance against the selected simulated soils was evaluated. The method of the second test was also based on the first test.

[0037] In the second test, four chelating agents E to H, different from the chelating agents used in the first test, were selected as samples. The components of each of the chelating agents E to H, as well as the concentration and pH of the sample solutions, are shown in Table 2. Purified water was used for dilution. If the pH of the sample solution is in the neutral range, partial corrosion of the turbine impeller 4 may occur depending on the components of the chelating agent. Therefore, the sample solution used in the second test was adjusted to have an alkaline pH of around pH 11.

[0038] [Table 2]

[0039] Figure 4 is a graph showing the evaluation results of the cleaning performance in the second test. In the second test, the test temperature and immersion time (test time) were constant. Specifically, the test temperature was 100°C, and the immersion time was 3 hours, at which point the amount of dissolved artificial soil reached saturation. For comparison, the results are also shown for the case where purified water was used instead of the chelating agent.

[0040] Referring to Figure 4, chelating agents E, G, and H have better cleaning properties than purified water. However, while chelating agent E showed good results in terms of soil retention, solidification of the filtrate was observed. Therefore, it is difficult to use chelating agent E as the chelating agent to be included in Cleaning Agent CL. Furthermore, when the artificial soil was calcium sulfate, chelating agent F showed a higher retention rate than purified water, and solidification of the filtrate was also observed in this case, suggesting the formation of calcium salts. Therefore, it is difficult to use chelating agent F as the chelating agent to be included in Cleaning Agent CL. Furthermore, when comparing chelating agents G and H, as is clear from Figure 4, the cleaning properties of chelating agent H are better than those of chelating agent G, regardless of whether the artificial soil is calcium sulfate or vanadium pentoxide.

[0041] Thus, the evaluation of the second test, which was obtained by comparing the preselected chelating agents E to H, showed that the chelating agent that is desirable to include in the cleaning agent CL is chelating agent H, which contains 2-hydroxy-1,3-diaminopropanetetraacetic acid.

[0042] The first and second tests described above were immersion tests using simulated fouling. In addition, the inventors prepared a fouled turbine impeller 4 from an actual machine and performed immersion cleaning (at room temperature) during maintenance and direct injection cleaning (at high temperature) during operation of the marine turbocharger 1. In these additional immersion cleaning and direct injection cleaning tests, the cleaning performance was evaluated using chelating agent A and purified water in addition to the above-mentioned chelating agent C and chelating agent H. In both immersion cleaning and direct injection cleaning, it was visually confirmed that the cleaning performance was better when using a cleaning agent containing chelating agent C or chelating agent H than when attempting to remove fouling using a cleaning agent containing chelating agent A or purified water.

[0043] Next, a third test was conducted to identify the components of the additives to be contained in the cleaning agent CL. Here, direct injection cleaning of the marine turbocharger 1 in operation is carried out in an environment of 150 to 250°C. Therefore, in the third test, additives that are effective in suppressing the inhibition of adhesion to the turbine impeller 4 (adhesion retention) and the reduction in spreading on the surface (spreadability) were studied even when the cleaning agent containing the identified chelating agent is used in such a high-temperature environment.

[0044] Table 3 shows the components of five additives A to E selected for the third test and the evaluation results of adhesion retention. The various additives A to E used as samples were prepared so that they were blended at 25 wt% or 50 wt% in aqueous solutions diluted with purified water. These aqueous additive solutions were then further blended into the above-mentioned chelating agent aqueous solution containing chelating agent C to a concentration of 0.1 mol / L.

[0045] [Table 3]

[0046] The adhesion retention was judged as being better (◯) or not (×) than cleaning with purified water alone. As shown in the results in Table 3, the chelating agent aqueous solution containing 50 wt% additive aqueous solution can retain on a stainless steel plate (SUS304) at 250°C, regardless of whether any of additives A to E was used.

[0047] Figure 5 is a graph showing the evaluation results of spreadability in the third test. Regarding spreadability, the greater the spread of the droplets of the chelating agent aqueous solution, the better the spreadability is evaluated. In particular, in a high-temperature environment of 200°C or higher, only Additive E obtained good results. This is presumably because the other Additives A to D have lower boiling points than Additive E and volatilize more quickly.

[0048] Thus, the evaluation in the third test, which was obtained by comparing the pre-selected additives A to E, showed that it was desirable to add additive E, which contains glycerin, to cleaner CL in order to maintain or improve adhesion retention and spreadability.

[0049] Next, the effects of the cleaning agent CL according to the present embodiment, the marine turbocharger 1 using the cleaning agent, and the method for cleaning the turbine impeller 4 of the marine turbocharger 1 will be described.

[0050] The cleaning agent CL according to the present embodiment is a cleaning agent used for cleaning the turbine impeller 4 of the marine turbocharger 1, and contains hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid.

[0051] Such cleaning agent CL contains any of the above substances as a chelating agent, and therefore can improve cleaning performance compared to conventional cleaning agents, even if the dirt adhering to the turbine impeller 4 is mainly fuel residue discharged from a marine internal combustion engine that uses heavy oil or the like as fuel. Here, cleaning agent CL can be used for both direct injection cleaning, which is performed mainly in a high-temperature environment during operation of the marine turbocharger 1, and immersion cleaning, which is performed mainly in a room-temperature environment during maintenance of the marine turbocharger 1. Furthermore, when cleaning agent CL contains the above chelating agent, the chelating agent aqueous solution constituting cleaning agent CL may be adjusted to have a pH in the alkaline range. In this regard, as shown in the above evaluation results, when cleaning dirt adhering to the turbine impeller 4, not all cleaning agents will contribute to improving cleaning performance as long as they contain a chelating agent aqueous solution adjusted to a pH in the alkaline range. The cleaning agent CL according to this embodiment may be particularly effective when it contains either hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid, even among aqueous chelating agent solutions whose pH is adjusted to the alkaline range.

[0052] As described above, according to the present embodiment, it is possible to provide the cleaning agent CL that improves the cleaning effect when removing dirt adhering to the turbine impeller 4. Furthermore, by cleaning the turbine impeller 4 with such a cleaning agent CL, it is possible to improve the turbocharger efficiency of the marine turbocharger 1 that includes the turbine impeller 4.

[0053] The cleansing agent CL according to this embodiment may also contain glycerin.

[0054] Such a detergent CL contains glycerin as an additive, so that it can maintain or improve adhesion retention and spreadability.

[0055] On the other hand, the marine turbocharger 1 according to this embodiment includes a turbine impeller 4 that rotates upon receiving exhaust gas discharged from a combustor of a marine internal combustion engine, and a turbine housing 2 in which the turbine impeller 4 is disposed. The marine turbocharger 1 includes an exhaust pipe 3 that is connected to an exhaust gas inlet 2a provided in the turbine housing 2 and that introduces the exhaust gas discharged from the combustor into the turbine housing 2. The marine turbocharger 1 also includes a cleaning agent tank 5 that stores a cleaning agent used to clean the turbine impeller 4, and a cleaning agent piping 6 that distributes the cleaning agent from the cleaning agent tank 5 to the exhaust pipe 3. A wall portion 3a of the exhaust pipe 3 has an inlet 7 that communicates with an open end 6a on the discharge side of the cleaning agent piping 6 and that injects the cleaning agent into the exhaust pipe 3. The cleaning agent is the cleaning agent CL described above.

[0056] According to such a marine turbocharger 1, the cleaning agent CL stored in the cleaning agent tank 5 can be supplied to the inside of the exhaust pipe 3 via the cleaning agent piping 6 and sprayed onto the turbine impeller 4 from the inlet 2a of the turbine housing 2. Therefore, direct injection cleaning, in which the cleaning agent CL is sprayed onto the turbine impeller 4 to clean it, particularly while the marine turbocharger 1 is in operation, can be performed with a simpler configuration. Furthermore, the cleaning agent CL used in direct injection cleaning contains hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid, and therefore, as described above, the cleaning effect when removing dirt adhering to the turbine impeller 4 can be improved.

[0057] As described above, according to this embodiment, it is possible to provide a marine turbocharger 1 that improves the cleaning effect when removing dirt adhering to the turbine impeller 4.

[0058] Furthermore, in the marine turbocharger 1 according to the present embodiment, in a range downstream of the inlet 7 in the exhaust pipe 3, the angle θ formed by the axial direction of the exhaust pipe 3 at the position where the inlet 7 is provided and the axial direction of the opening end 6 a on the discharge side of the cleaning agent piping 6 may be an acute angle.

[0059] According to such a marine turbocharger 1, regardless of the pipe shapes of the exhaust pipe 3 or the cleaning agent piping 6, the cleaning agent piping 6 assumes a posture in which it is tilted toward the downstream side of the exhaust pipe 3 near the injection port 7. Therefore, the cleaning agent CL that flows along the extension direction of the cleaning agent piping 6 and is finally injected from the injection port 7 tends to head toward the inlet 2a side of the turbine housing 2, that is, toward the turbine impeller 4, as shown in FIG. 1. This can be advantageous for the spraying of the cleaning agent CL onto the surface of the turbine impeller 4.

[0060] Moreover, the method for cleaning the turbine impeller 4 of the marine turbocharger 1 according to the present embodiment includes the steps of generating combustion gas in a combustor, introducing a cleaning agent into the combustion gas, and supplying the combustion gas containing the cleaning agent to the turbine impeller 4. The cleaning agent is the above-described cleaning agent CL.

[0061] According to such a cleaning method, the cleaning agent CL used in the direct injection cleaning including the above steps contains hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid. Therefore, as described above, the cleaning effect in removing dirt attached to the turbine impeller 4 can be improved.

[0062] In the embodiment described above, there is one exhaust pipe 3 that introduces exhaust gas discharged from the combustor of the marine internal combustion engine into the marine turbocharger 1. However, the number of exhaust pipes 3 connected to the inlet 2a of the turbine housing 2 is not necessarily limited to one, and may be two or more. For example, as shown in Fig. 6, in the case where two exhaust pipes, a first exhaust pipe 20 and a second exhaust pipe 21, are connected to the inlet 2a of the turbine housing 2, the inlet 7 may be provided in both the wall portion 20a of the first exhaust pipe 20 and the wall portion 21a of the second exhaust pipe 21.

[0063] Although several embodiments have been described, the embodiments can be modified or varied based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined, unless they contradict each other. [Explanation of symbols]

[0064] 1 Marine turbocharger 2 Turbine housing 2a entrance 3 exhaust pipe 3a wall 4 Turbine impeller 5 Detergent Tank 6 Cleaning agent piping 6a Open end 7 Inlet CL Cleaning Agent

Claims

1. a turbine impeller that rotates upon receiving exhaust gas discharged from a combustor of a marine internal combustion engine that uses heavy oil as fuel; a turbine housing in which the turbine impeller is disposed; an exhaust pipe connected to the exhaust gas inlet provided in the turbine housing and introducing the exhaust gas discharged from the combustor into the turbine housing; a cleaning agent tank containing a cleaning agent used to clean the turbine impeller; a cleaning agent pipe that distributes the cleaning agent from the cleaning agent tank to the exhaust pipe, a wall portion of the exhaust pipe has an injection port that communicates with an open end on a discharge side of the cleaning agent pipe and that injects the cleaning agent into the inside of the exhaust pipe, The cleaning agent contains 2-hydroxy-1,3-diaminopropanetetraacetic acid.

2. 2. The marine turbocharger according to claim 1, wherein, in a range downstream of the inlet in the exhaust pipe, an angle formed between an axial direction of the exhaust pipe at a position where the inlet is provided and an axial direction of the opening end on a discharge side of the cleaning agent pipe is an acute angle.

3. The marine turbocharger according to claim 1 or 2, wherein the cleaning agent contains glycerin.

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