Detergent, marine turbocharger, and method for cleaning turbine impeller of marine turbocharger

Abstract

To provide a cleaning agent and a marine supercharger each of which improves cleaning effect upon removal of dirt attached to a turbine impeller.SOLUTION: A cleaning agent CL used to clean 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 comprises: a 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 for introducing exhaust gas discharged from the combustor into the interior of the turbine housing 2; a cleaning agent tank 5 housing the cleaning agent CL; and cleaning agent piping 6 for flowing the cleaning agent Cl from the cleaning tank 5 to the exhaust pipe 3. A wall portion 3a of the exhaust pipe 3 has an injection port 7 communicating with an opening 6a of the discharge side of the cleaning agent pipe 6 and injecting the cleaning agent CL into the exhaust pipe 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a cleaning agent used for cleaning a turbine impeller, a marine turbocharger using the cleaning agent, and a method for cleaning a turbine impeller of a marine turbocharger. [Background technology]

[0002] Conventionally, in gas turbines as internal combustion engines including blades, dirt may adhere to the surface of turbine blades during operation. The accumulation of such dirt is undesirable as it can cause the rotation of the turbine to become unstable. In response to this, Patent Document 1 discloses a technology related to a cleaning liquid injected from the inlet side of the turbine compressor section located upstream of the combustor, mainly for cleaning the turbine compressor section.

[0003] On the other hand, in marine turbochargers that are installed in marine internal combustion engines that use heavy oil as fuel and that include blades similar to gas turbines, solidified dirt, mainly combustion residues, may adhere to the surface of the turbine impeller during operation. In order to remove such dirt 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 possible to use a cleaning agent as 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 are based on the heavy oil, so that the use of a conventional cleaning agent does not necessarily lead to an improvement in the cleaning effect.

[0007] In view of this, an object of the present disclosure is to provide a cleaning agent that improves the cleaning effect when removing dirt adhered to a turbine impeller, a marine turbocharger, and a cleaning method for a turbine impeller of a marine turbocharger. [Means for solving the problem]

[0008] One aspect of the present disclosure is Installed on a marine internal combustion engine fueled by heavy oil A cleaning agent used to clean a turbine impeller of a marine turbocharger, comprising: 2 -Hydroxy-1,3-diaminopropanetetraacetic acid.

[0009] The cleaning agent may contain glycerin.

[0012] In addition, according to another aspect of the present disclosure , installed on a marine internal combustion engine fueled by heavy oil C The method for cleaning a turbine impeller of a marine turbocharger includes the steps of generating a 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, wherein the cleaning agent 2 -Hydroxy-1,3-diaminopropanetetraacetic acid. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a cleaning agent that improves the cleaning effect when removing dirt adhering to a turbine impeller, a marine turbocharger, and a cleaning method for a turbine impeller of a marine turbocharger. [Brief description of the drawings]

[0014] [Figure 1]FIG. 1 is a schematic diagram showing a configuration of a marine turbocharger according to one embodiment. [Diagram 2] 1 is a graph showing the evaluation results of temperature dependency of cleaning effect in a first test. [Diagram 3] 1 is a graph showing the evaluation results of the time dependency of cleaning effect in a first test. [Figure 4] 13 is a graph showing the evaluation results regarding cleaning performance in the second test. [Diagram 5] 1 is a graph showing the evaluation results of spreadability in the third test. [Figure 6] FIG. 11 is a schematic diagram showing a configuration of a marine turbocharger according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, some exemplary embodiments will be described with reference to the drawings. 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 given the same reference numerals to avoid repeated explanations, and elements not directly related to the present disclosure are not illustrated.

[0016] 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 re-supplies compressed air generated by utilizing exhaust gas discharged from the marine internal combustion engine in order to improve engine performance and fuel efficiency.

[0017] 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.

[0018] The turbine housing 2 accommodates a turbine impeller 4 therein. 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 therein to the outside.

[0019] 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 hollow arrow. In this embodiment, there is only one exhaust pipe 3, and it is depicted as a straight pipe in FIG. 1. However, the exhaust pipe 3 may be a curved pipe.

[0020] 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 rotor on which a plurality of blades are formed. A rotating shaft (not shown) is coaxially connected to the turbine impeller 4.

[0021] 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 in the air inlet. The compressor impeller is specifically a disk-shaped rotating body having a plurality of blades formed thereon. The above-mentioned rotating shaft is coaxially connected to the compressor impeller from the opposite side to the turbine impeller 4. The compressor impeller can compress the air introduced into the compressor housing by rotating itself as the turbine impeller 4 rotates after receiving the exhaust gas.

[0022] The cleaning agent tank 5 contains 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.

[0023] The cleaning agent pipe 6 distributes the cleaning agent CL from the cleaning agent tank 5 to the exhaust pipe 3. An opening 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 for injecting the cleaning agent CL into the inside of the exhaust pipe 3. An opening end 6a on the discharge side of the cleaning agent pipe 6 is connected to 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 branched from a midway position so that there is one pipe on the upstream side connected to the cleaning agent tank 5 and two pipes on the downstream side connected to the two injection ports 7.

[0024] 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 regulating valve 16. The first valve 10 is provided in each of the two cleaning agent pipes 6 after branching, and can individually adjust, for example, whether or not to inject the cleaning agent CL from each inlet 7, or the amount of the cleaning agent CL injected into the exhaust pipe 3. The second valve 12 is provided in the cleaning agent pipe 6 before branching and in the vicinity of the cleaning agent tank 5, and switches, for example, whether or not to inject the cleaning agent CL. The second valve 12 is opened during cleaning in which the cleaning agent CL is injected, and closed when cleaning using the cleaning agent CL is not performed. The operator can adjust the amount of the cleaning agent CL injected by adjusting the pressure with the pressure regulating valve 16 while checking the value indicated by the pressure gauge 14.

[0025] Further, downstream of the injection port 7 in the exhaust pipe 3, the angle θ between the axial direction of the exhaust pipe 3 at the position where the injection port 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 injection port 7 in this embodiment has a cut-out shape, the injection port 7 may further be provided with an orifice, a sprayer, or the like.

[0026] Next, a description will be given of the cleaning agent CL used for cleaning the turbine impeller 4, which can be adopted in the marine turbocharger 1. Here, in order to identify the cleaning agent CL suitable for cleaning the turbine impeller 4, the following test was carried out.

[0027] First, a first test was conducted to identify the components of the chelating agent to be contained in the cleaning agent CL. In the first test, artificial foulants that are assumed to adhere to the surface of the turbine impeller 4 due to the 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 the 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.

[0028] 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 value obtained by adjusting it to a 10-fold diluted solution.

[0029] [Table 1]

[0030] As the first test method, first, various sample solutions (aqueous solutions of chelating agents) are prepared by diluting chelating agents A to D as shown in Table 1. Next, weighed artificial soil (approximately 0.5 g) is placed in a 30 ml screwed 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 time. However, during the time of standing, a shaking operation is performed every 24 hours. After the specified time has passed, the contents of the test tube are filtered using a weighed 1 μ membrane filter, and the filtrate is dried and then weighed. Then, the remaining ratio (%) of the artificial soil is calculated from the weight of the filtrate.

[0031] In the first test, two types of reagents were selected as simulated soils and evaluated for each reagent. The first reagent was calcium sulfate dihydrate (CaSO 4 2H 2The second reagent is vanadium pentoxide (V 2 O 5 ) (99%, particle size: up to 100 μm). Here, if the marine internal combustion engine is a marine diesel engine fueled by heavy oil C (Japanese Industrial Standard: JIS K 2205; heavy oil type 3), the dirt adhering to the surface of the turbine impeller 4 will be mainly fuel residues, which are inorganic residues such as calcium sulfate and vanadium pentoxide. In other words, the reagents used in the evaluation of the first test are selected to be substances similar to the components of actual dirt.

[0032] FIG. 2 is a graph showing the evaluation results of the temperature dependency of the cleaning effect in the first test. FIG. 2(a) shows the results when the artificial soil is calcium sulfate. FIG. 2(b) shows the results when the artificial soil is vanadium pentoxide. In both evaluations, the results when purified water (pH 5.7) was used instead of the chelating agent are also included for comparison. Here, the test temperatures [°C] on the horizontal axis are 25 (room temperature), 50, and 100, and the immersion time (test time) is 72 hours. Since 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.

[0033] 2(a), when the artificial dirt is calcium sulfate, each of the various sample solutions has better cleaning properties than purified water. Also, according to the results, it is found that among the chelating agents A to C, the cleaning properties of the chelating agent C are better.

[0034] Referring to FIG. 2(b), in the case where the pseudo-foulant is vanadium pentoxide, chelating agent B has the best cleaning performance at a temperature of 25°C. However, in the case of chelating agent B, the dirt remaining rate increases rapidly as the temperature increases. This is presumably because vanadium salts were formed when chelating agent B was used, since weight increase and solidification of the pseudo-foulant (change from powder to solid) were confirmed at a temperature of 100°C. In particular, considering that cleaning using cleaning agent CL may be performed during operation of the marine turbocharger 1, it is not desirable for cleaning performance to decrease at high temperatures. For this reason, 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 these chelating agents A to D, as in the case where the pseudo-foulant is calcium sulfate.

[0035] FIG. 3 is a graph showing the evaluation results of the time dependency of the cleaning effect in the first test. FIG. 3(a) shows the results when the artificial soil is calcium sulfate. FIG. 3(b) shows the results when the artificial soil is vanadium pentoxide. Again, in both evaluations, the results when purified water was used instead of the chelating agent are included for comparison. Here, the immersion time (test time) [hours] on the horizontal axis is 1, 3, 6, 24, 48 and 72, and the test temperature is 25°C (room temperature).

[0036] 3(a) and 3(b), it can be seen that the cleaning properties of chelating agent B and chelating agent C are better than those of chelating agent A or purified water. Here, with respect to chelating agent C, regardless of whether the artificial dirt is calcium sulfate or vanadium pentoxide, the amount of dissolved artificial dirt reaches saturation after an immersion time of 1 hour. In other words, it is considered that, as long as the immersion time is within the range of 1 to 3 hours, chelating agent C is easier to remove dirt than chelating agent B, regardless of whether the artificial dirt is calcium sulfate or vanadium pentoxide.

[0037] Thus, the evaluation of the first test obtained by comparing the preselected chelating agents A to D reveals that the chelating agent that is desirable to be contained in the cleaning agent CL is chelating agent C, which contains hydroxyethyliminodiacetic acid.

[0038] Next, the 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 dirt in advance, as in the first test, and the cleaning performance against the selected simulated dirt was evaluated. The method of the second test was also based on that of the first test.

[0039] 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 the chelating agents E to H, as well as the concentrations 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 may occur in the turbine impeller 4 depending on the components of the chelating agent. Therefore, the sample solution used in the second test is adjusted to be in the alkaline range of about pH 11.

[0040] [Table 2]

[0041] FIG. 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 the amount of dissolved artificial soil reached saturation. For comparison, the results are also included for the case where purified water was used instead of the chelating agent.

[0042] Referring to FIG. 4, chelating agents E, G, and H have better cleaning properties than purified water. However, although chelating agent E showed good results in terms of dirt remaining rate, solidification of the filtrate was confirmed. Therefore, it is difficult to use chelating agent E as a chelating agent to be included in cleaning agent CL. Furthermore, when the artificial dirt is calcium sulfate, chelating agent F showed a higher remaining rate than purified water, and solidification of the filtrate was also confirmed in this case, so it is presumed that calcium salts were formed. Therefore, it is difficult to use chelating agent F as a chelating agent to be included in cleaning agent CL. Furthermore, when comparing chelating agents G and H, as is clear from FIG. 4, the cleaning properties of chelating agent H are better than those of chelating agent G, regardless of whether the artificial dirt is calcium sulfate or vanadium pentoxide.

[0043] Thus, the evaluation of the second test obtained by comparing the preselected chelating agents E to H shows that the chelating agent that is desirable to be contained in the cleaning agent CL is chelating agent H, which contains 2-hydroxy-1,3-diaminopropanetetraacetic acid.

[0044] The first and second tests so far are immersion tests using artificial fouling. In response to this, the inventor further prepared an actual turbine impeller 4 with fouling attached thereto, 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 tests of immersion cleaning and direct injection cleaning, in addition to the above-mentioned chelating agent C and chelating agent H, chelating agent A and purified water were used to evaluate the cleanability. In both immersion cleaning and direct injection cleaning, it was visually confirmed that the cleanability was better when a cleaning agent containing chelating agent C or chelating agent H was used than when an attempt was made to remove fouling using a cleaning agent containing chelating agent A or purified water.

[0045] 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 performed in an environment of 150 to 250°C. In the third test, therefore, additives that are effective in suppressing the inhibition of adhesion to the turbine impeller 4 (adhesion retention) and the decrease in spread on the surface (spreadability) were studied even when the cleaning agent containing the above-specified chelating agent is used in such a high-temperature environment.

[0046] Table 3 shows the components of the five additives A to E selected for the third test and the evaluation results of adhesion retention. The various additives A to E as samples were adjusted to be mixed at 25 wt% or 50 wt% in an aqueous solution diluted with purified water. These aqueous additive solutions were further mixed into the aqueous chelating agent solution containing the above-mentioned chelating agent C so that the concentration was 0.1 mol / L.

[0047] [Table 3]

[0048] The adhesion retention was judged based on whether it was 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 be retained on a stainless steel plate (SUS304) at 250°C, regardless of whether any of additives A to E was used.

[0049] 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. Particularly 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 evaporate faster.

[0050] Thus, the evaluation in the third test obtained by comparing the pre-selected additives A to E shows that it is desirable to add additive E, which contains glycerin, to cleaner CL in order to maintain or improve adhesion retention and spreadability.

[0051] Next, the effects of the cleaning agent CL according to the present embodiment, the marine turbocharger 1 using the same, and the cleaning method for the turbine impeller 4 of the marine turbocharger 1 will be described.

[0052] 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.

[0053] Such cleaning agent CL contains any one of the above substances as a chelating agent, and therefore can improve cleaning performance compared to the conventional method, 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, the cleaning agent CL can be used for either direct injection cleaning performed mainly in a high-temperature environment during operation of the marine turbocharger 1, or immersion cleaning performed mainly in a room-temperature environment during maintenance of the marine turbocharger 1. In addition, when the cleaning agent CL contains the above chelating agent, the chelating agent aqueous solution constituting the cleaning agent CL may be adjusted to 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 inclusion of either hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid in the cleaning agent CL according to this embodiment can be particularly effective among those in which the pH of the aqueous chelating agent solution is adjusted to be in the alkaline range.

[0054] As described above, according to the present embodiment, it is possible to provide a cleaning agent CL that improves the cleaning effect when removing dirt attached 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 including the turbine impeller 4.

[0055] The cleaning agent CL according to this embodiment may contain glycerin.

[0056] Such a detergent CL contains glycerin as an additive, so that adhesion retention and spreadability can be maintained or improved.

[0057] 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 inside of 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 injection port 7 that communicates with an open end 6a on the discharge side of the cleaning agent piping 6 and injects the cleaning agent into the inside of the exhaust pipe 3. The cleaning agent is the above-mentioned cleaning agent CL.

[0058] 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 during operation of the marine turbocharger 1, can be performed with a simpler configuration. In addition, the cleaning agent CL used in the direct injection cleaning contains hydroxyethyliminodiacetic acid or 2-hydroxy-1,3-diaminopropanetetraacetic acid, and therefore, as described above, the cleaning effect when removing dirt attached to the turbine impeller 4 can be improved.

[0059] In this way, 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.

[0060] Furthermore, in the marine turbocharger 1 according to the present embodiment, in a range downstream of the exhaust pipe 3 from the injection port 7, the angle θ between the axial direction of the exhaust pipe 3 at the position where the injection port 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.

[0061] 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 falls toward the downstream side of the exhaust pipe 3 in the vicinity of 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 flow toward the introduction port 2a side of the turbine housing 2, that is, toward the turbine impeller 4 side, as shown in Fig. 1. This can be advantageous for the spread of the cleaning agent CL onto the surface of the turbine impeller 4.

[0062] 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-mentioned cleaning agent CL.

[0063] 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.

[0064] In the embodiment described above, there is one exhaust pipe 3 that introduces the 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.

[0065] Although several embodiments have been described, the embodiments can be modified or modified based on the above disclosure. All components of the above embodiments and all features described in the claims may be individually extracted and combined as long as they are not mutually inconsistent. [Explanation of symbols]

[0066] 1. Marine turbocharger 2 Turbine housing 2a Introduction 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 cleaning agent used to clean turbine impellers of marine turbochargers installed in marine internal combustion engines fueled by heavy fuel oil, comprising: A cleaning agent containing 2-hydroxy-1,3-diaminopropanetetraacetic acid.

2. 2. The cleaning agent of claim 1, which contains glycerin.

3. A method for cleaning a turbine impeller of a marine turbocharger installed in a marine internal combustion engine fueled by heavy oil, comprising: generating combustion gas in a combustor; introducing a cleaning agent into the combustion gas; supplying the combustion gas containing the cleaning agent to the turbine impeller; The cleaning method for a turbine impeller of a marine turbocharger, wherein the cleaning agent contains 2-hydroxy-1,3-diaminopropanetetraacetic acid.

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