Silencer

Abstract

Effectively suppresses water hammer. [Solution] The silencer 20 comprises a main body 21 having a steam passage 31 formed therein and a shaft portion 26 that is submerged in drain. The passage 31 has a throttling section 33, a drain suction port 35 formed in the shaft portion 26, a mixing section 34 that communicates with the throttling section 33 and the suction port 35 and, as steam flows in from the throttling section 33, sucks the drain from the suction port 35 and mixes it with the steam, and an outlet 36 formed in the shaft portion 26 that discharges the steam mixed with the drain in the mixing section 34. The throttling section 33 has a passage cross-sectional area that decreases in multiple stages from the upstream side.

Description

Technical Field

[0001] The technology of the present disclosure relates to a silencer that mixes steam with drain water.

Background Art

[0002] For example, as disclosed in Patent Document 1, a silencer for suppressing the occurrence of water hammer is known. The silencer described in Patent Document 1 has a suction member through which steam flows. In the suction member, a suction port is provided in the side wall, and a discharge port is provided in the bottom wall. The steam in the suction member mixes with the drain water flowing in from the suction port and condenses to some extent, and then is discharged from the discharge port. Therefore, it becomes difficult for lumps of steam to form in the drain water, and the occurrence of water hammer is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the silencer as described above, there is room for improvement in the water hammer suppression effect.

[0005] The technology of the present disclosure has been made in view of such circumstances, and its object is to effectively suppress water hammer.

Means for Solving the Problems

[0006] The silencer of this disclosure comprises a body having a steam flow path and a submerged section that is submerged in drain. The flow path has a throttling section, a drain suction port formed in the submerged section, a mixing section communicating with the throttling section and the suction port, which draws in drain from the suction port and mixes it with steam as steam flows in from the throttling section, and an outlet formed in the submerged section for discharging the steam mixed with drain in the mixing section. The throttling section has a flow path cross-sectional area that decreases in multiple stages from the upstream side. [Effects of the Invention]

[0007] According to the silencer, water hammer can be effectively suppressed. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a piping diagram showing the drain recovery system. [Figure 2] Figure 2 is a cross-sectional view showing the silencer. [Figure 3] Figure 3 is an enlarged cross-sectional view of the main part of the silencer. [Figure 4] Figure 4 is an enlarged cross-sectional view of the main part of the modified silencer. [Modes for carrying out the invention]

[0009] The following describes exemplary embodiments in detail with reference to the drawings. Figure 1 is a piping diagram showing the drain recovery system 1.

[0010] The drain recovery system 1 heats an object with steam and recovers the resulting drain. The drain recovery system 1 comprises a steam supply pipe 11, a steam usage section 13, a drain recovery pipe 14, a plurality of drain discharge pipes 16, and a plurality of silencers 20.

[0011] The steam supply pipe 11 is connected to the steam usage section 13. The steam supply pipe 11 is connected to, for example, a boiler system (not shown), and steam generated in the boiler system is supplied to the steam usage section 13. The steam supply pipe 11 is equipped with a pressure reducing valve 12 to adjust the steam pressure.

[0012] The steam utilization section 13 is, for example, a heat exchanger. In the steam utilization section 13, steam supplied from the steam supply pipe 11 condenses upon the object, heating it. The steam becomes condensate (condensed water) through condensation. In other words, in the steam utilization section 13, the object is latently heated by the latent heat of condensation of the steam.

[0013] The drain recovery pipe 14 is connected to the steam usage section 13. In the drain recovery pipe 14, condensate generated by steam condensation in the steam usage section 13 is recovered. The drain recovery pipe 14 is, for example, located below the steam usage section 13, and is configured to allow condensate to flow from the steam usage section 13 to the drain recovery pipe 14. The drain recovery pipe 14 is an example of drain piping through which condensate flows.

[0014] A liquid pumping device 15 is provided in the drain recovery pipe 14. The liquid pumping device 15 is a pump that pumps the drain generated in the steam usage section 13 downstream through the drain recovery pipe 14. For example, in the liquid pumping device 15, the drain from the steam usage section 13 flows in through the drain recovery pipe 14 and is temporarily stored. When the amount of stored drain reaches a predetermined amount, high-pressure working gas is introduced into the liquid pumping device 15, and the drain stored in the liquid pumping device 15 is pumped (discharged) downstream by the pressure of the working gas. Once the drain is pumped, drain again flows in from the steam usage section 13 into the liquid pumping device 15 and is stored. In this way, the inflow of drain and the pumping (discharge) of drain alternate in the liquid pumping device 15.

[0015] The plurality of drain discharge pipes 16 are connected between the steam supply pipe 11 and the drain recovery pipe 14. Specifically, the plurality of drain discharge pipes 16 are provided in sequence in the axial direction of the steam supply pipe 11, and are provided at intervals (for example, 20 to 30 m) from each other. Each drain discharge pipe 16 has its upstream end connected to the steam supply pipe 11 and its downstream end connected to the drain recovery pipe 14 via a silencer 20.

[0016] The drain discharge pipe 16 collects the drain generated in the steam supply pipe 11 into the drain recovery pipe 14. That is, in the steam supply pipe 11, a part of the steam may condense and become drain, and that drain, specifically, the high-temperature drain is collected into the drain recovery pipe 14 via the drain discharge pipe 16 and the silencer 20.

[0017] A steam trap 17 is provided in the middle of the drain discharge pipe 16. The steam trap 17 allows the drain generated in the steam supply pipe 11 to flow in through the drain discharge pipe 16. The steam trap 17 is an automatic valve that automatically discharges only the inflowing drain to the downstream side by the pressure difference between its upstream and downstream (that is, the difference between the upstream pressure and the downstream pressure). In actuality, drain mixed with steam flows into the steam trap 17.

[0018] In this way, the drain generated in the steam supply pipe 11 merges with the drain generated in the steam usage section 13 in the drain recovery pipe 14 and is pressure-fed to the downstream side. The drain recovery pipe 14 is arranged below the steam supply pipe 11, and the drain discharge pipe 16 extends in the vertical direction and is connected to the upper part of the drain recovery pipe 14 via a silencer 20.

[0019] 〈Configuration of the silencer〉 FIG. 2 is a cross-sectional view showing the silencer 20. FIG. 3 is an enlarged cross-sectional view of the main part of the silencer 20. The silencer 20 is provided straddling the drain recovery pipe 14 and the drain discharge pipe 16. The silencer 20 suppresses water hammer by mixing steam with drain inside it.

[0020] The silencer 20 includes a main body 21. A steam flow path 31 is formed in the main body 21. The main body 21 has a shaft portion 26 that is submerged in the drain. The shaft portion 26 is an example of a submerged portion.

[0021] Specifically, the main body 21 is formed in a substantially rod shape extending in the upstream and downstream directions. In the main body 21 shown in FIG. 2, the upper side is the upstream side and the lower side is the downstream side. In this example, the main body 21 is connected to the drain discharge pipe 16 and the drain recovery pipe 14 while extending in the vertical direction. More specifically, the main body 21 extends in the same direction as the axis of the drain discharge pipe 16 and also extends in a direction orthogonal to the axis of the drain recovery pipe 14.

[0022] The main body 21 further has a head portion 22. In the main body 21, the shaft portion 26 is continuously formed on the downstream side of the head portion 22, that is, below the head portion 22.

[0023] The head portion 22 is connected to the drain discharge pipe 16 and the drain recovery pipe 14. The head portion 22 has a prism portion 23, a first connection portion 24, and a second connection portion 25.

[0024] The prism portion 23 is formed in a flat substantially hexagonal prism shape, and the axial direction thereof coincides with the vertical direction. The first connection portion 24 is formed in a cylindrical shape coaxial with the prism portion 23 and is continuously formed on the upstream side of the prism portion 23, that is, above the prism portion 23. For example, a tapered female thread is formed in the first connection portion 24, and the downstream end of the drain discharge pipe 16 is connected thereto. The second connection portion 25 is formed in a substantially cylindrical shape coaxial with the prism portion 23 and is continuously formed on the downstream side of the prism portion 23, that is, below the prism portion 23. For example, a tapered male thread is formed in the second connection portion 25. The second connection portion 25 is connected to the drain recovery pipe 14. More specifically, the second connection portion 25 is screwed into a connection hole 14a provided in the upper portion of the drain recovery pipe 14. That is, the main body 21 is connected to the drain recovery pipe 14 by screwing the second connection portion 25 into the connection hole 14a. The outer diameters of the first connection portion 24 and the second connection portion 25 are smaller than the outer shape of the prism portion 23.

[0025] The shaft portion 26 is formed in a cylindrical shape coaxial with the head portion 22 and extends in the up-down direction, i.e., vertical direction. The shaft portion 26 is formed continuously downstream of the second connection portion 25, i.e., below the second connection portion 25. The shaft portion 26 is the part that is submerged in the drain of the drain recovery pipe 14 when the main body 21 is connected to the drain recovery pipe 14.

[0026] As described above, a steam passage 31 is formed inside the main body 21, and more specifically, a steam and drain passage 31 is formed. The passage 31 has an inlet 32, a throttling section 33, a mixing section 34, a suction port 35, and an outlet 36.

[0027] The inlet 32 ​​is formed in the head portion 22 of the head portion 22 and the shaft portion 26. More specifically, the inlet 32 ​​opens on the upstream end face of the head portion 22 and extends in the upstream and downstream directions. The female thread described above is formed on the inner circumferential surface of the inlet 32, and the drain discharge pipe 16 is connected to the inlet 32. In other words, steam and drain flow into the inlet 32 ​​from the drain discharge pipe 16.

[0028] The throttling section 33 is formed spanning the head section 22 and the shaft section 26. The throttling section 33 communicates with the inlet 32 ​​and accelerates the depressurization of the steam flowing in from the inlet 32. In other words, the throttling section 33 increases the steam flow velocity and decreases the steam pressure. Specifically, the flow path cross-sectional area of ​​the throttling section 33 is smaller than the flow path cross-sectional area of ​​the inlet 32. In this example, the flow path cross-sectional area of ​​the throttling section 33 is smaller than the flow path cross-sectional areas of the mixing section 34, the suction port 35, and the outlet 36. The throttling section 33 extends in a straight line. Note that the throttling section 33 may be formed only on the shaft section 26.

[0029] Furthermore, the flow path cross-sectional area, i.e., the inner diameter, of the throttling section 33 decreases in multiple stages from the upstream side. In this example, the flow path cross-sectional area of ​​the throttling section 33 decreases in two stages. Specifically, the throttling section 33 has a first throttling section 33a and a second throttling section 33b, which has a smaller flow path cross-sectional area than the first throttling section 33a. The second throttling section 33b is connected to the downstream end of the first throttling section 33a and is also in communication with the mixing section 34. More specifically, the second throttling section 33b is directly connected to the mixing section 34. The length of the second throttling section 33b in the flow direction, i.e., the length in the direction of the axis A1, is shorter than that of the first throttling section 33a.

[0030] The mixing section 34 communicates with the throttling section 33 and the suction port 35. Steam flows in from the throttling section 33, drawing in drain from the suction port 35 and mixing it with the steam. The mixing section 34 is located on the shaft section 26. The mixing section 34 is connected to the downstream end of the throttling section 33 and is formed in a cylindrical shape coaxial with the throttling section 33. The throttling section 33 and the mixing section 34 extend in the direction of the axis A1 of the shaft section 26, and more specifically, are formed coaxially with the shaft section 26. In the mixing section 34, the pressure decreases as steam flows at high speed from the throttling section 33, and the drain from the drain recovery pipe 14 is drawn in through the suction port 35.

[0031] The suction port 35 is formed in the shaft portion 26 and sucks the drain from the drain recovery pipe 14. The suction port 35 is located to the side of the mixing portion 34 and opens onto the outer circumferential surface of the shaft portion 26. More specifically, multiple suction ports 35 are formed in the circumferential direction of the shaft portion 26. In this example, four suction ports 35 are formed. The multiple suction ports 35 are arranged at equal intervals from one another.

[0032] As shown in Figure 3, the opening axis A2 of each of the multiple suction ports 35 extends in a direction perpendicular to the axis A1, i.e., horizontally. In other words, the suction ports 35 open horizontally. The silencer 20 is connected to the drain recovery pipe 14 such that at least one of the multiple suction ports 35 opens toward the upstream side US of the drain recovery pipe 14. Alternatively, all of the multiple suction ports 35 may open toward the downstream side DS of the drain recovery pipe 14.

[0033] The outlet 36 is formed in the shaft section 26 and discharges the steam mixed with drain in the mixing section 34 into the drain recovery pipe 14. Specifically, the outlet 36 is connected to the downstream end of the mixing section 34 and is formed in a cylindrical shape coaxial with the mixing section 34. In other words, the outlet 36 extends in the direction of the axis A1 of the shaft section 26, and more specifically, is formed coaxially with the shaft section 26. The outlet 36 opens to the downstream end face of the shaft section 26, i.e., the lower end face of the shaft section 26. In this example, the flow path cross-sectional area of ​​the outlet 36 is larger than the flow path cross-sectional area of ​​the mixing section 34.

[0034] The silencer 20 further includes a porous member 41. The porous member 41 is a filter that allows drain to flow into the suction port 35 while preventing foreign matter from flowing into the suction port 35. Specifically, the porous member 41 is formed in a cylindrical shape and is provided on the outer circumference of the shaft portion 26. The porous member 41 covers the suction port 35. The porous member 41 has many small holes that can prevent foreign matter from passing through. Examples of materials that can be used as the porous member 41 include metal mesh, perforated metal, expanded metal, and fine wire sintered bodies.

[0035] <Silencer operation> The operation of the silencer 20 configured in this way will now be explained. High-temperature condensate discharged from the steam trap 17 flows into the silencer 20 and out into the condensate recovery pipe 14. In other words, the high-temperature condensate passes through the inlet 32 ​​and the throttling section 33 and flows into the mixing section 34, where it mixes with the low-temperature condensate in the condensate recovery pipe 14 that is sucked in from the suction port 35. The mixed condensate flows out into the condensate recovery pipe 14 from the outlet 36. In this way, the condensate generated in the steam supply pipe 11 is recovered in the condensate recovery pipe 14 via the silencer 20.

[0036] Some of the condensate discharged from the steam trap 17 may re-evaporate and become steam, i.e., flash steam. This is because the condensate flowing from the steam supply pipe 11 into the steam trap 17 is at a high temperature, and when this high-temperature condensate is discharged from the steam trap 17, the pressure drops. The re-evaporated steam flows into the silencer 20.

[0037] In the silencer 20, the steam flowing into the inlet 32 ​​flows into the throttling section 33. The steam is accelerated and depressurized as it flows through the throttling section 33. The accelerated and depressurized steam then flows through the mixing section 34 and out to the outlet 36. As the steam flows through the mixing section 34 at high speed in this manner, the pressure in the mixing section 34 decreases. Therefore, the low-temperature drain from the drain recovery pipe 14 is drawn into the mixing section 34 through the four suction ports 35 and mixes with the steam.

[0038] Here, the throttling section 33 is formed by a first throttling section 33a and a second throttling section 33b, and the flow path cross-sectional area is reduced in two stages. Therefore, compared to the case where the flow path cross-sectional area of ​​the throttling section is constant over its entire length, that is, where the second throttling section 33b, which has a smaller flow path cross-sectional area, is formed over its entire length, the flow resistance, i.e., pressure loss, over the entire length of the throttling section 33 is reduced. Furthermore, the length of the second throttling section 33b in the flow direction is shorter than that of the first throttling section 33a. Therefore, the proportion occupied by the second throttling section 33b, which has a smaller flow path cross-sectional area, in the throttling section 33 is reduced as much as possible. As a result, the flow resistance in the throttling section 33 is further reduced. In this way, the flow rate of high-temperature drain flowing into the silencer 20 is increased by reducing the flow resistance in the throttling section 33.

[0039] The steam mixed with the low-temperature drain in the mixing section 34 flows out from the outlet 33. The steam is finely dispersed by mixing with the low-temperature drain in the mixing section 34. In this way, the steam is finely dispersed by the silencer 20 and flows out into the drain recovery pipe 14, suppressing water hammer that occurs in the drain recovery pipe 14. Furthermore, since some of the steam condenses when it mixes with the low-temperature drain in the mixing section 34, water hammer is also suppressed in the drain recovery pipe 14 as a result.

[0040] If the steam flows into the drain recovery pipe 14 without being dispersed, a relatively large mass of steam (space) will form in the drain recovery pipe 14 as the steam flows in. This mass of steam will be cooled by the surrounding low-temperature drain and rapidly condense, causing the space where the steam was to exist to instantly become a vacuum. The surrounding drain will then flow into this vacuum space all at once, and water hammer will occur as the drains collide with each other or with the pipe wall of the drain recovery pipe 14.

[0041] In this embodiment, the steam is finely dispersed by the silencer 20 and flows into the drain recovery pipe 14, making it difficult for large steam clumps (spaces) to form in the drain recovery pipe 14. Therefore, the vacuum space generated by the rapid condensation of steam is small. Consequently, the generation of large water hammers that cause noise and pipe damage is suppressed. In other words, the size of the water hammer is reduced.

[0042] As described above, the silencer 20 comprises a main body 21 having a steam passage 31 formed therein and a shaft portion 26 that is submerged in the drain. The passage 31 has a throttling section 33, a drain suction port 35 formed in the shaft portion 26, a mixing section 34 that communicates with the throttling section 33 and the suction port 35 and, as steam flows in from the throttling section 33, sucks the drain from the suction port 35 and mixes it with the steam, and an outlet 36 formed in the shaft portion 26 that discharges the steam mixed with the drain in the mixing section 34. The cross-sectional area of ​​the passage in the throttling section 33 decreases in multiple stages from the upstream side.

[0043] In this configuration, the steam is accelerated and depressurized as it flows through the throttling section 33. As the accelerated steam flows through the mixing section 34, the pressure in the mixing section 34 decreases. Therefore, the low-temperature drain from the drain recovery pipe 14 is drawn into the mixing section 34 through the suction port 35 and mixes with the steam.

[0044] Here, since the flow path cross-sectional area of ​​the throttling section 33 is reduced in two stages, the flow resistance in the throttling section 33 can be reduced compared to the case where the flow path cross-sectional area is constant along the entire length of the throttling section. Therefore, a decrease in the flow rate of drain flowing into the silencer 20 can be suppressed. As a result, the degree of throttling can be increased without significantly reducing the amount of drain flowing in. As the degree of throttling increases, the amount of drain suction at the suction port 35 increases, which can promote the mixing action of steam and drain in the mixing section 34. In this way, the mixing action is promoted, and the steam is more dispersed and flows out into the drain recovery pipe 14, so water hammer can be sufficiently suppressed. In this way, water hammer can be suppressed without significantly reducing the amount of drain flowing into the silencer 20, i.e., the amount of drain recovered, so water hammer can be effectively suppressed.

[0045] Furthermore, the throttling section 33 has a first throttling section 33a and a second throttling section 33b which is connected to the downstream end of the first throttling section 33a and communicates with the mixing section 34, and has a smaller flow path cross-sectional area than the first throttling section 33a. The length of the second throttling section 33b in the flow direction is shorter than that of the first throttling section 33a.

[0046] With this configuration, since the length of the second throttling section 33b in the flow direction is shorter than that of the first throttling section 33a, the proportion occupied by the second throttling section 33b, which has a smaller flow path cross-sectional area, can be kept as low as possible in the throttling section 33. This further reduces the flow resistance in the throttling section 33. Therefore, the decrease in the amount of drain flowing into the silencer 20 is more suppressed, and water hammer can be suppressed more effectively.

[0047] Variant form This modified version is a modified version of the silencer 20 in the above embodiment, with a change in the configuration of the suction port 35. The differences from the above embodiment will be explained here. Figure 4 is an enlarged cross-sectional view of the main part of the modified silencer 20.

[0048] As shown in Figure 4, the suction ports 38 in this modified example are formed on the shaft portion 26, similar to the embodiment described above, and more specifically, they open onto the outer circumferential surface of the shaft portion 26. In this example as well, four suction ports 38 are formed in the circumferential direction of the shaft portion 26.

[0049] Unlike the embodiment described above, the suction port 38 opens upward. More specifically, the suction port 38 opens diagonally upward on the outer circumferential surface of the shaft portion 26. In other words, the opening axis A4 of each of the multiple suction ports 38 intersects the axis A1 diagonally such that the angle it makes with the horizontal axis A3 is a predetermined angle θ. The angle θ is acute. With this configuration, the suction ports 38 open in a direction substantially opposite to the direction in which gravity acts.

[0050] In this modified silencer 20, the steam flows through the mixing section 34 at high speed, causing the low-temperature drain from the drain recovery pipe 14 to be drawn into the mixing section 34 from the suction port 38. Here, as mentioned above, the suction port 38 opens in a direction approximately opposite to the direction in which gravity acts, so the drain flows into the suction port 38 more easily than, for example, if the suction port opens horizontally. Furthermore, the direction in which the drain flows into the suction port 38 (i.e., diagonally downward) is approximately the same as the direction in which the steam flows through the throttling section 33 and the mixing section 34 (i.e., downward). Therefore, the drain flows into the suction port 38 even more easily.

[0051] As the drain is more easily drawn into the suction port 38, the amount of drain suction at the suction port 38 increases, thus promoting the mixing of steam and drain in the mixing section 34. As a result, the steam is more dispersed and flows out into the drain recovery pipe 14, which effectively suppresses water hammer. The other configurations, operations, and effects are the same as in the above embodiment.

[0052] Other embodiments As described above, the embodiments described herein have been presented as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited thereto and can be applied to embodiments that have been modified, replaced, added, or omitted as appropriate. Furthermore, it is possible to combine the components described in the embodiments above to create new embodiments. In addition, the components described in the attached drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem, in order to illustrate the technology. Therefore, the mere presence of such non-essential components in the attached drawings and detailed description should not be immediately assumed to mean that those non-essential components are essential.

[0053] For example, the throttling section 33 may have a flow path cross-sectional area that decreases in three or more stages.

[0054] Furthermore, as long as the overall flow resistance of the aperture portion 33 does not have an effect, the length of the second aperture portion 33b in the flow direction may be equal to or greater than the length of the first aperture portion 33a in the flow direction.

[0055] Furthermore, the shaft portion 26 is not limited to being a cylindrical shape extending in the vertical direction, but may also be formed in a cylindrical shape extending horizontally, for example.

[0056] Furthermore, the number of suction ports 35 and 38 may be one or more than four.

[0057] Furthermore, although the outlet 36 opens to the lower end surface of the shaft portion 26, it may instead open to the outer circumferential surface of the shaft portion 26. In other words, instead of the outlet 36 causing the steam mixed with drain in the mixing portion 34 to flow downward, it may be configured to flow sideways from the shaft portion 26. Specifically, the outlet 36 opens toward the upstream side US or the downstream side DS of the drain recovery pipe 14. By causing the steam to flow sideways from the shaft portion 26, particularly toward the upstream side US or the downstream side DS of the drain recovery pipe 14, erosion of the drain recovery pipe 14 caused by the outflow of fluid from the silencer 20 can be suppressed. [Industrial applicability]

[0058] As described above, the technology of this disclosure is useful for silencers that mix steam with condensate. [Explanation of Symbols]

[0059] 20 Silencers 21 Main unit 26. Shaft section (submerged part) 31 Flow channels 33 Aperture section 33a First aperture section 33b Second aperture section 34 Mixing section 35 Suction port 36 Outlet 38 Suction port A1 axis center

Claims

1. A silencer comprising a body having a steam passage and a submerged portion that is submerged in drain, The flow path comprises a constricted section, a drain suction port formed in the submerged section, a mixing section communicating with the constricted section and the suction port, which draws in the drain from the suction port and mixes it with the steam as steam flows in from the constricted section, and an outlet formed in the submerged section for discharging the steam mixed with the drain in the mixing section. The aforementioned constricted section has a flow path cross-sectional area that decreases in multiple stages from the upstream side. A silencer characterized by the following features.

2. In the silencer according to claim 1, The throttling section comprises a first throttling section and a second throttling section connected to the downstream end of the first throttling section and communicating with the mixing section, and having a smaller flow path cross-sectional area than the first throttling section. The second diaphragm has a shorter length in the flow direction than the first diaphragm. A silencer characterized by the following features.

3. In the silencer according to claim 1 or 2, The aforementioned suction port opens upward. A silencer characterized by the following features.

4. In the silencer according to claim 3, The submerged portion is formed in a cylindrical shape extending in the vertical direction. The aforementioned throttling section and the aforementioned mixing section extend in the direction of the axis of the submerged section, The suction port opens diagonally upward on the outer surface of the submerged portion. A silencer characterized by the following features.

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