Underwater smoke exhaust safety chimney

Abstract

The underwater smoke exhaust safety chimney comprises a chimney pipeline, a breather valve, a Venturi pipeline and a water pump, the breather valve comprises a smoke connector, an air connector and a mixed outlet, the smoke connector is connected with the chimney pipeline, and the air connector is used for being connected with the atmosphere; the Venturi pipeline comprises a contraction section, a throat part and an expansion section, the contraction section is connected with the mixing outlet, and the water pump is connected with the throat part; when negative pressure exists in the breather valve, the air connector is communicated with the mixed outlet, and when positive pressure exists in the breather valve, the smoke connector is communicated with the mixed outlet. Through cooperation of the breather valve, the Venturi tube and the water pump, the risk of seawater backflow of the chimney is effectively avoided under the condition that no supercharger works, and the smoke exhaust safety and stability are improved; after the ship supercharger works normally, the Venturi pipeline can assist in sucking smoke in the chimney, and the exhaust efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ship equipment, and in particular to an underwater smoke exhaust safety chimney. Background Art

[0002] At present, high-speed boats generally adopt an engine layout with multiple turbochargers working alternately. The exhaust system is equipped with double chimneys and adopts side exhaust technology. The smoke passes through transverse pipes and is discharged to the sides of the ship. The high-temperature smoke discharged directly enters the air, which not only affects the crew, but also causes high-temperature deformation of the hull outer plate, reduces strength and other adverse effects.

[0003] In order to reduce the heat radiation of exhaust smoke and enhance stealth, some high-speed boats use underwater smoke exhaust technology. The outlet of the chimney is located at a certain height below the waterline. When the smoke is discharged, it needs to overcome the pressure difference of the water level above the exhaust port, the resistance required for the smoke to squeeze the water laterally to form a sufficient exhaust channel, and the smoke flow resistance. When the high-speed boat is cruising, the chimney with a supercharger will not take in water because of the engine exhaust pressure. For the chimney without a supercharger, when the water inlet pressure head is high, seawater will flow back into the chimney under the action of water pressure.

[0004] To prevent seawater backflow, a butterfly valve is typically installed at the top of the chimney. However, when the engine is started, the butterfly valve is always open to maintain optimal exhaust back pressure. If the crew improperly operates the valve, wave action can cause waves to flow back into the chimney and even into the cylinders, causing serious damage to the engine. Therefore, it is necessary to design a safe chimney structure for underwater smoke exhaust on high-speed boats to solve this problem. Summary of the Invention

[0005] Purpose of the invention: In view of the disadvantage that seawater backflow is prone to occur when the existing underwater smoke exhaust chimney works without a supercharger, the present invention provides an underwater smoke exhaust safety chimney, which can effectively prevent seawater backflow from occurring in the chimney and improve the safety of smoke exhaust.

[0006] Technical solution: In order to solve the above problems, the present invention adopts an underwater smoke exhaust safety chimney, including a chimney pipe, a breathing valve, a Venturi pipe and a water pump. The breathing valve includes a smoke interface, an air interface and a mixing outlet. The smoke interface is connected to the chimney pipe, and the air interface is used to connect to the atmosphere; the Venturi pipe includes a contraction section, a throat and an expansion section, the contraction section is connected to the mixing outlet, and the water pump is connected to the throat; when the breathing valve is under negative pressure, the air interface is connected to the mixing outlet, and when the breathing valve is under positive pressure, the smoke interface is connected to the mixing outlet.

[0007] Furthermore, it also includes a butterfly valve, which is installed on the chimney pipe.

[0008] Furthermore, the butterfly valve is made of a special alloy material that is resistant to high temperatures and corrosion, and the surface of the valve plate is coated with an anti-oxidation coating.

[0009] Furthermore, the valve body of the breathing valve is made of nickel-based alloy material, and the thermal expansion coefficient matches the chimney pipe within an error of ±5%.

[0010] Furthermore, a filter is provided in the air interface.

[0011] Furthermore, the contraction angle of the contraction section is 20°, and the expansion angle of the expansion section is 10°.

[0012] Furthermore, the water pump is a corrosion-resistant centrifugal pump.

[0013] Furthermore, the water pump is provided with a water inlet pipe and a water outlet pipe, the water outlet pipe is connected to the throat, and a filter is provided in the water inlet pipe.

[0014] Furthermore, the flue gas interface is connected to the chimney pipe through a neck butt welding flange.

[0015] Furthermore, the mixing outlet and the contraction section are connected by welding using an argon arc welding process.

[0016] Beneficial effects: Compared with the existing technology, the significant advantage of the present invention is that, through the cooperation of the breathing valve, the Venturi tube and the water pump, the risk of seawater backflow into the chimney can be effectively avoided when the supercharger is not working, thereby improving the safety and stability of smoke exhaust; when the boat supercharger is working normally, the Venturi pipe can assist in extracting the smoke in the chimney, thereby improving the exhaust efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the overall structure of the underwater smoke exhaust safety chimney of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the breathing valve of the present invention;

[0019] Figure 3 It is a schematic diagram of the Venturi pipeline structure of the present invention. DETAILED DESCRIPTION

[0020] like Figures 1 to 3 As shown in the figure, an underwater smoke exhaust safety chimney in this embodiment includes a chimney pipe 1, a butterfly valve 2, a breathing valve 3, a Venturi pipe 4, and a water pump 5. The butterfly valve 2 is installed on the chimney pipe 1. The butterfly valve 2 is made of a special alloy material that is resistant to high temperatures and corrosion. The valve plate is coated with an anti-oxidation coating to ensure long-term stable operation in high-temperature flue gas environments. The butterfly valve 2 is equipped with a limit switch to provide real-time feedback on the open and closed position of the butterfly valve.

[0021] The breathing valve 3 is connected to the exhaust end of the chimney pipe 1. The valve body of the breathing valve 3 is made of nickel-based alloy material, and the thermal expansion coefficient matches the chimney pipe 1 within an error of ±5%, to avoid deformation caused by temperature difference and resulting in sealing failure. The breathing valve 3 includes a flue gas interface 31, an air interface 32 and a mixing outlet 33, and a high-temperature graphite sealing ring is configured at each interface. The flue gas interface 31 is connected to the chimney pipe 1 through a neck butt-welded flange. The flange bolts are made of high-temperature alloy and are uniformly pre-tightened. The air interface 32 is used to connect to the atmosphere, and a filter is provided inside to prevent external impurities from entering the system. The mixing outlet 33 is connected to the Venturi pipe 4.

[0022] The Venturi conduit 4 consists of a contracting section 41, a throat 42, and a diverging section 43. The contracting angle of the contracting section 41 is 20°, while the diverging angle of the diverging section 43 is 10°. The top of the contracting section 41 is welded to the mixing outlet 33 using argon arc welding. The water pump 5 is a corrosion-resistant centrifugal pump equipped with an inlet pipe 51 and an outlet pipe 52. The inlet pipe 51 is equipped with a filter for extracting seawater, and the outlet pipe 52 is connected to the throat 42.

[0023] The present invention operates as follows: The upper smoke inlet of the chimney pipe 1 is connected to the ship's hull smoke channel. The outlet of the expansion section 43 of the venturi pipe 4 is positioned a certain distance below the waterline, determined by the hull profile, to ensure a uniform flow field at the smoke outlet. A water pump 5 is installed in the cabin and connected to the seawater via a water inlet pipe 51.

[0024] When the high-speed boat engine is initially started, the turbocharger has not yet reached the operating speed. At this time, the exhaust pressure in the chimney is insufficient to overcome the back pressure of the external seawater. Under this working condition, the water pump 5 runs at the rated speed, sucking in and pressurizing the external seawater through the water inlet pipe 51, forming a high-pressure water flow with a pressure of 0.25-0.3MPa. The high-pressure water flow is transported to the throat 42 of the Venturi pipe 4 through the outlet pipe 52. Since the cross-sectional area of the throat 42 suddenly decreases, according to the Bernoulli principle, the water flow velocity increases sharply here. When the high-speed water flow is discharged from the end of the expansion section 43, a high-speed jet is formed at the smoke outlet. The dynamic pressure generated by the jet is sufficient to offset the static pressure of the external seawater, forming a "water seal" on the outside of the smoke outlet to ensure that seawater cannot flow back into the chimney through the smoke outlet.

[0025] As water continues to flow out of the end of expansion section 43, a localized negative pressure zone forms in the upper region of the Venturi duct 4, between the mixing outlet 33 and the throat 42, due to the entrainment of the fluid. When the pressure in this region drops below atmospheric pressure, the negative pressure valve of the breathing valve 3 automatically opens in response to the pressure differential. At this point, the air port 32 connects to the mixing outlet 33, allowing outside air to enter the top region of the Venturi duct 4, maintaining pressure balance within the chimney and preventing deformation of the duct due to excessive negative pressure.

[0026] When the high-speed boat's engine speed rises above 75% of its rated operating speed, the turbocharger fully engages, the flue gas exhaust pressure gradually increases, and the positive pressure valve of breather valve 3 opens, connecting the flue gas interface 31 to the mixing outlet 33. The system enters normal exhaust mode. At this point, the high-temperature flue gas in the chimney, at a temperature of approximately 400-600°C, enters the breather valve through the flue gas interface 31, and then flows into the Venturi duct 4 through the mixing outlet 33. After entering the contraction section 41, the flue gas accelerates, reaching its maximum velocity in the throat 42 area, before decelerating and increasing in pressure in the expansion section 43. At this point, the flue gas exhaust pressure is significantly higher than the external seawater back pressure, allowing the flue gas to be stably discharged from the exhaust port at the end of the expansion section 43. The Venturi effect generates a certain negative pressure in the throat 42 during the flue gas exhaust process. This negative pressure assists in drawing the flue gas out of the chimney, improving exhaust efficiency. The speed of the water pump 5 is adjusted or stopped in real time based on the exhaust pressure to avoid energy interference between the water pump and the flue gas exhaust process.

Claims

1. An underwater smoke exhaust safety chimney, characterized in that: The invention comprises a chimney pipe (1), a breathing valve (3), a venturi pipe (4) and a water pump (5); the breathing valve (3) comprises a smoke interface (31), an air interface (32) and a mixing outlet (33); the smoke interface (31) is connected to the chimney pipe (1), and the air interface (32) is used to connect to the atmosphere; the venturi pipe (4) comprises a contraction section (41), a throat (42) and an expansion section (43); the contraction section (41) is connected to the mixing outlet (33), and the water pump (5) is connected to the throat (42); when the pressure inside the breathing valve (3) is negative, the air interface (32) is connected to the mixing outlet (33); when the pressure inside the breathing valve (3) is positive, the smoke interface (31) is connected to the mixing outlet (33).

2. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: It also includes a butterfly valve (2), which is installed on the chimney pipe (1).

3. The underwater smoke exhaust safety chimney according to claim 2, characterized in that: The butterfly valve (2) is made of a special alloy material that is resistant to high temperatures and corrosion, and the surface of the valve plate is plated with an anti-oxidation coating.

4. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The valve body of the breathing valve (3) is made of nickel-based alloy material, and the thermal expansion coefficient matches the chimney pipe (1) within an error of ±5%.

5. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: A filter is provided in the air interface (32).

6. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The contraction angle of the contraction section (41) is 20°, and the expansion angle of the expansion section (43) is 10°.

7. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The water pump (5) is a corrosion-resistant centrifugal pump.

8. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The water pump (5) is provided with a water inlet pipe (51) and a water outlet pipe (52), the water outlet pipe (52) is connected to the throat (42), and a filter is provided in the water inlet pipe (51).

9. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The flue gas interface (31) is connected to the chimney pipe (1) via a neck-welded flange.

10. The underwater smoke exhaust safety chimney according to claim 1, characterized in that: The mixing outlet (33) and the contraction section (41) are connected by welding using an argon arc welding process.

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