Podcast
Questions and Answers
What role does the non-return valve in the supply line serve?
What role does the non-return valve in the supply line serve?
What is the purpose of the oil mist in the sealing air?
What is the purpose of the oil mist in the sealing air?
Which feature allows an engineer to verify the closing and rotation of the valve?
Which feature allows an engineer to verify the closing and rotation of the valve?
Which device serves as a visual indication of air pressure within the cylinder?
Which device serves as a visual indication of air pressure within the cylinder?
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What type of fuel is primarily used in low-speed diesel engines mentioned?
What type of fuel is primarily used in low-speed diesel engines mentioned?
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What material is primarily used to construct valve cages in low-speed diesel engines?
What material is primarily used to construct valve cages in low-speed diesel engines?
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Why is a detachable seat utilized in the valve cage design?
Why is a detachable seat utilized in the valve cage design?
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What is the primary function of the valve cage in a low-speed diesel engine?
What is the primary function of the valve cage in a low-speed diesel engine?
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How is the valve connected to the cylinder cover?
How is the valve connected to the cylinder cover?
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What power range do low-speed diesel engines typically operate within?
What power range do low-speed diesel engines typically operate within?
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What type of fuel is typically used in low-speed diesel engines?
What type of fuel is typically used in low-speed diesel engines?
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What characteristic allows the detachable seat to withstand thermal loading?
What characteristic allows the detachable seat to withstand thermal loading?
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How are studs attached to the valve cage?
How are studs attached to the valve cage?
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What year marked the cooperation between Rudolf Diesel and Sulzer for the construction of the first Sulzer diesel engine?
What year marked the cooperation between Rudolf Diesel and Sulzer for the construction of the first Sulzer diesel engine?
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Which characteristic helps distinguish low-speed diesel engines mentioned?
Which characteristic helps distinguish low-speed diesel engines mentioned?
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What is the primary purpose of the sheathed lubricating oil pipe in low-speed diesel engines?
What is the primary purpose of the sheathed lubricating oil pipe in low-speed diesel engines?
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How can defective operation of the exhaust valve be detected?
How can defective operation of the exhaust valve be detected?
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What feature of low-speed diesel engines contributes to their significant size and weight?
What feature of low-speed diesel engines contributes to their significant size and weight?
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What is a potential consequence of a high-pressure (HP) pipe connection leaking?
What is a potential consequence of a high-pressure (HP) pipe connection leaking?
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What is the primary purpose of using Stellite in valve seat applications?
What is the primary purpose of using Stellite in valve seat applications?
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Which components are incorporated in the valve seat assembly for low-speed diesel engines?
Which components are incorporated in the valve seat assembly for low-speed diesel engines?
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What material primarily composes the Nimonic family of alloys?
What material primarily composes the Nimonic family of alloys?
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What is the function of the bronze bush in the valve body?
What is the function of the bronze bush in the valve body?
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In low-speed diesel engines, how is the exhaust valve cooled?
In low-speed diesel engines, how is the exhaust valve cooled?
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What is the role of the O-ring in the valve assembly?
What is the role of the O-ring in the valve assembly?
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Which of the following statements about low-speed diesel engines is incorrect?
Which of the following statements about low-speed diesel engines is incorrect?
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What material is primarily used for valve spindles due to its wear and corrosion resistance at elevated temperatures?
What material is primarily used for valve spindles due to its wear and corrosion resistance at elevated temperatures?
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Which characteristic is NOT associated with Inconel 625?
Which characteristic is NOT associated with Inconel 625?
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When burning low quality residual fuels, why is material selection crucial for valve components?
When burning low quality residual fuels, why is material selection crucial for valve components?
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What is the primary purpose of coating the underside of the valve disc with materials like Inconel 625?
What is the primary purpose of coating the underside of the valve disc with materials like Inconel 625?
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What is a common feature of valves used in low-speed diesel engines?
What is a common feature of valves used in low-speed diesel engines?
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What is the role of spinners or valve rotators in low-speed diesel engines?
What is the role of spinners or valve rotators in low-speed diesel engines?
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Which composite material offers greater wear resistance and fewer environmental issues compared to chrome for valve stems?
Which composite material offers greater wear resistance and fewer environmental issues compared to chrome for valve stems?
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Which of the following is NOT a benefit of using Nimonic for valve applications?
Which of the following is NOT a benefit of using Nimonic for valve applications?
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What is the primary fuel type used in low-speed diesel engines described?
What is the primary fuel type used in low-speed diesel engines described?
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Which component is responsible for the delivery of oil to the exhaust valve cylinder during engine operation?
Which component is responsible for the delivery of oil to the exhaust valve cylinder during engine operation?
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What function does the air spring cylinder serve in the exhaust valve system?
What function does the air spring cylinder serve in the exhaust valve system?
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Where is the make-up oil connection located in the actuator pump system?
Where is the make-up oil connection located in the actuator pump system?
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What action occurs during the downward stroke of the actuator pump piston?
What action occurs during the downward stroke of the actuator pump piston?
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What is the purpose of the relief valve in the actuator pump system?
What is the purpose of the relief valve in the actuator pump system?
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What happens to the piston fitted to the valve stem when the valve opens?
What happens to the piston fitted to the valve stem when the valve opens?
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Which of the following statements accurately describes the operation of the actuator pump?
Which of the following statements accurately describes the operation of the actuator pump?
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Study Notes
Marine Internal Combustion Engines
- Rudolf Diesel collaborated with Sulzer to create the first Sulzer diesel engine in 1898.
- Low-speed diesel engines range from 1500 to 100,000 kW of shaft power.
- These engines use heavy fuel oil (H.F.O.) and are two-stroke with a crosshead mechanism.
- Tankers, bulk carriers, and large container ships predominantly use these types of engines for propulsion.
- Engines are enormously large and remarkably high due to their crosshead construction.
- Engines can reach heights of 14 meters, lengths of 30 meters, and weigh 2300 tons.
Lubricating Oil Pipe (Sheathed Pipe)
- The lubricating oil pipe is a two-layered pipe.
- Curved lines represent the lubricating oil supply lines for the exhaust valves.
- Exhaust valves and valve casings exceed two meters in dimensions.
- Braided sheathing surrounds the pipes (similar to some home gas heaters).
- Sheathed pipe is a pipe covered by another layer of metal.
Sheathing (Safety Measure)
- Sheathing is implemented to safeguard the high-pressure pipe from leakage.
- Leakage from the high-pressure pipe connecting the valve lube oil pump and cylinder could lead to a fire hazard from hydraulic oil spraying onto the hot exhaust manifold.
- The high-pressure pipe is surrounded by a braided steel pipe, separating the two by a narrow gap.
- Sheathing acts as a crucial safety measure.
Failure Detection in High-Pressure (Sheathed) Pipe
- Defective Exhaust Valve Operation: Poor cylinder performance—measured by exhaust temperatures—can indicate an issue with the exhaust valve.
- Leaking Oil: Oil leaking between the high-pressure and braided pipes, often through small holes in the actuator pump body, can enter the cam box.
Exhaust Valve
- Exhaust valves have a cage structure resembling a birdcage.
- They have four studs that are hydraulically tightened using nuts.
- The cage is made of cast iron to withstand mechanical and thermal loads, although a detachable seat is sometimes employed.
Valve Cage
- Valve cages are uniquely designed for single exhaust valves located centrally within the cylinder cover.
Detachable Seat
- Detachable seats are typically made from molybdenum steel to resist thermal and corrosive environments.
- Detachable seats are easily machined once removed from the cage.
Exhaust Valve Cooling
- Valve cages are water-cooled as part of the engine's cooling system.
- Valve cooling water generally flows from the cylinder cover to the exhaust valve body via cooling bends.
- In certain instances, there's a direct connection between the cylinder cover's water space and the valve cage's seat region.
Exhaust Valve Seal/Bush
- A bronze bush (shown hatched) guides the valve spindle within the valve body.
- The seal prevents spindle wear and air leakage from the cylinder.
Exhaust Valve Spindle
- Nimonic is a high-strength, corrosion-resistant nickel-based alloy primarily used for valve spindles due to its resistance at elevated temperatures.
- Engine designs often utilize Nimonic for the entire valve, given the high loading.
- Material selection, such as choosing between Nimonic alloys, is important to maximize engine life when burning fuel with high levels of Sulphur, vanadium, or other damaging chemicals.
Exhaust Valve Rotator/Spinner/Rotating Mechanism
- Spinners prevent valve tilting, uneven forces, overheating, and accumulation of solidified exhaust slags on the valve's sealing surfaces.
- Spinners induce gentle grinding on sealing surfaces to effectively remove corrosive vanadium pentoxide slag.
- The even sealing action minimizes tilting and prevents uneven thermal stress.
- Valve rotation distributes uneven combustion forces more uniformly on the valve seat, preventing localized wear/tear.
- Spinning the valve also reduces the wear and tear on valve guides.
Exhaust Valve Hydraulic Cylinder
- A piston located atop the valve stem and spindle operates within a hydraulic cylinder connected to an oil pump via a sheathed high-pressure pipe.
Exhaust Valve Actuator/Oil Pump
- The camshaft-driven actuator pump delivers hydraulic oil to the valve cylinder during the piston's upward stroke.
- Oil returns to the pump cylinder during the piston's downward movement.
- A relief valve in the actuator pump body manages pressure to prevent over-pressurization of the system.
- Separate fuel and hydraulic-oil pumps are involved.
Exhaust Valve Air Spring Cylinder
- An air spring cylinder introduces positive force to ensure valve closure after the hydraulic opening force is removed; it is a supplementary valve closing mechanism.
- A piston fitted to the valve stem reciprocates within the cylinder, compressing air within during valve opening.
- Compressing air provides force to close the valve once the hydraulic force on the valve is deactivated.
- The air leakage and system pressure (5 bar) are regulated via a non-return valve to prevent backward air flow.
- The cylinder wall is lubricated by a controlled oil bleed from the hydraulic cylinder to limit wear on the seals.
- Oil mist, containing compressed air and small oil particles (less than 10 µm), is used to aid this process.
Exhaust Valve Air Spring Cylinder, Tell-tale
- A device called a Tell-tale provides a visual display of the air pressure within the exhaust valve cylinder to manage cylinder pressure; it is a visual indicator for cylinder pressure.
- Glass tubes filled with liquid visually indicate air pressure.
- Electronic indicators/digital readout can also track the air pressure, offering more precise measurements than liquid-based Tell-tales.
Exhaust Valve Air Spring Cylinder, Check Rod
- The check rod assists in confirming proper valve lifting and cyclical rotation.
- Located at the top of the casing, the spring-loaded check rod passes through a bush and contacts a groove in the main air piston.
- As the piston rises, it causes the check rod to lift, and this motion indicates that the valve is closing.
- Movement of the check rod also indicates the rotating motion of the valve. This motion further suggests the valve is correctly positioned for smooth operation closure.
Exhaust Valve Detailed Components
- A diagram displays various components, including hydraulic oil, actuator piston, air supply, and valve parts, depicting an exhaust valve's intricate layout.
Low Speed, 2-Stroke, Crosshead Turbocharged Engine
- This section outlines the components (crankcase bedplate, crankcase, A-frame, fuel/oil pumps, cylinder block, cylinder liners, cylinder covers, exhaust-gas manifold, scavenging-air manifold) of a low-speed, two-stroke, turbocharged marine engine.
- The presentation discusses the relative positioning of exhaust and scavenging manifolds.
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Description
This quiz explores the fundamentals of marine internal combustion engines, including the historical development of Sulzer diesel engines and their applications in maritime vessels. Additionally, it covers the technical specifications of lubricating oil pipes and safety measures related to sheathing. Test your knowledge on these critical components of marine engineering.
