Ever pondered the complexity behind starting the massive engines that propel ships across the seas? With diesel engines becoming the go-to for new ships since the latter half of the 20th century, grasping the intricacies of their startup is vital for seamless operation. Understanding the key mechanisms involved is essential for efficient and smooth sailing.
Starting a ship's main engine is a complex task that requires careful checks and safety measures. It involves air start systems, hydraulic start systems, and electric start systems. These systems work together to get the engines running smoothly.
Compressed air systems play a key role in engine cranking. The engine turning gear makes sure the engine is in the right position for starting.
Before starting the engine, it's crucial to check and prepare important systems. This includes air, lubricating oil, cooling water, and fuel oil systems.
Now, let's dive into the fascinating world of ship main engine starting mechanisms. We'll look at the intricacies of marine diesel engines and the steps needed to start them.
Key Takeaways
Diesel engines have become the predominant choice for new ships since the second half of the 20th century.
Various starting mechanisms, including air start systems, hydraulic start systems and electric start systems, are used to start ship main engines.
Compressed air systems play a crucial role in engine cranking, while the engine turning gear ensures proper positioning before start-up.
Thorough checks and precautions must be taken for air systems, lubricating oil systems, cooling water systems, and fuel oil systems before starting the main engine.
Proper engine room watchkeeping and maintenance practices are essential for trouble-free operation, leading to higher efficiency and fewer breakdowns.
Overview of Ship's Main Engine Starting Systems
Main engine starting systems are vital for the reliable operation of ships. They initiate combustion in the engine and speed it up to the desired rpm. The choice of system varies based on engine type, space, and regulatory needs.
The primary main engine starting systems for marine diesel engines are air, electric, and hydraulic. Each system has distinct benefits.
Air start systems use compressed air to turn the engine crankshaft and start combustion. They're favored in large engines for their dependability and ease. Air is stored in receivers (large air reservoirs) and released into cylinders at high pressure to overcome resistance and start the engine.
Electric start systems employ electric motors for cranking. They're ideal for smaller engines (such as the Diesel Generators or the emergency engines), offering a compact and efficient solution. The electric motor connects to the engine flywheel, providing the torque needed to start the engine.
Hydraulic start systems rotate the engine with high-pressure hydraulic fluid. Although not frequently chosen, they have strong starting torque. They are employed in medium to large engines. Hydraulic fluid from a pump drives a hydraulic motor connected to the flywheel. This motor converts fluid pressure into mechanical rotation, which -in turn- cranks the engine.
The choice of starting system also hinges on the vessel's needs and environmental rules. Some vessels might need redundant systems for reliability, while others might prefer electric starts to cut emissions.
Here's a comparison of the main engine starting systems:
Starting System | Advantages | Disadvantages |
Air Start |
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Electric Start |
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Hydraulic Start |
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The choice depends on engine size, operational needs, and environmental laws. Air, electric, and hydraulic systems are common, each with pros and cons.
Preparing to Start Ship's Main Engine
Before starting a ship's main engine, it's vital to prepare thoroughly. This ensures the engine operates smoothly and safely. It involves checking and testing overhauled components and removing tools or equipment that might be lingering from previous overhaul & maintenance procedures. Main engine preparation is key to a successful start.
Checking and Testing Overhauled Components
During an engine overhaul, various components are inspected, repaired, or replaced. It's crucial to check that all overhauled components work correctly before starting the engine. This includes:
Cylinder liners, made of pearlite grey cast iron with vanadium and titanium, enhance strength, wear, and corrosion resistance. Chrome-plated liners offer longer life but are more expensive initially.
Piston crowns, crafted from chromium-molybdenum alloy steel, are strong, heat-resistant, and conduct heat well. Some MAN B&W engines have a hard nickel-chrome alloy layer on the piston crown.
Connecting rods, forged from steel, transmit the firing force and convert reciprocating motion to rotary motion in modern engines.
Engine Component | Material | Purpose |
Cylinder Liners | Pearlite grey cast iron with vanadium and titanium | Enhance strength, wear, and corrosion resistance |
Piston Crowns | Chromium-molybdenum alloy steel with chromium, molybdenum, and nickel | Provide strength, heat resistance, and thermal conductivity |
Connecting Rods | Forged steel | Transmit firing force and convert reciprocating motion to rotary motion |
Each component must be tested to ensure it works reliably during engine operation.
Removing Tools and Equipment Used During Overhaul
After the engine overhaul and component testing, remove all tools, equipment, or rags that might have been used during previous overhauls. Not doing so can cause severe damage or malfunctions when the engine starts. A detailed checklist should be followed to ensure all items are removed from the engine room.
Air Start Systems for Marine Diesel Engines
Air start systems are vital for starting marine diesel engines, especially in larger vessels. They offer advantages over electric starters, such as higher torque at startup and enhanced safety by eliminating ignition sources in flammable atmospheres. Starting air systems have two or more air reservoirs, providing redundancy for multiple engine starts.
Draining Water from Starting Air System
Before starting the main engine, draining water from the starting air system is crucial. Water can cause corrosion and reduce the efficiency of the compressed air system. Regular maintenance, including draining and cleaning, ensures optimal performance and longevity.
Pressurizing Air Systems and Ensuring Correct Pressures
After draining water, the air systems must be pressurized correctly. The required pressure depends on the engine type and size. For instance, slow-speed two-stroke marine engines need compressed air at about 30 bar (435 psi) pressure, directly into the cylinders. The Chief Engineer provides instructions on maintaining proper pressures online during maneuvering.
The air receiver on ships is sized to allow for several engine starts, requiring a large quantity of compressed air. If the system is maintained properly, up to 10-12 starts are possible with the stored air in the starting air system for marine diesel engines.
Compressed Air Availability at Exhaust Valve Closing Cylinders
Compressed air must be available at the exhaust valve closing cylinders for proper operation. The air distributor controls the compressed air flow to each air start valve, following the engine's firing order. Cylinder air start valves are closed by springs and opened by pilot air, allowing compressed air into the cylinder.
Routine checks include inspecting the main air starting valve pipes for temperature increases to detect leaks.
Starting Air System Component | Function |
Air Compressor | Compresses air to the required pressure for starting the engine |
Air Receiver | Stores compressed air for multiple engine starts |
Air Start Valve | Controls the flow of compressed air into the engine cylinder |
Air Distributor | Regulates the flow of compressed air to each air start valve based on the firing order |
Ensuring the air start systems function properly allows marine engineers to start the main engine reliably. Regular maintenance, including draining water, pressurizing, and checking for leaks, is key for the longevity and performance of marine diesel engines.
Lubricating Oil Systems for Main Engine Start-up
Before starting the ship's main engine, it is crucial to ensure that the lubricating oil systems are functioning properly. The main engine lubrication system is essential for preventing wear and tear, reducing friction, and dissipating heat. Proper checks and maintenance are vital for the smooth start-up and operation of the main engine.
Checking Oil Levels and Replenishing if Necessary
Before starting the main engine, the lubricating oil level in the engine sump should be checked. Lubricating oil is stored in the crankcase or a drain tank below the engine. The sump quantity should be calculated with the engine stopped but the lubricating oil pump running to ensure proper oil circulation. If the oil level is low, it must be replenished to maintain sufficient reserves, covering the main sump and an additional 20% for the intended voyage.
Starting Main Engine and Turbocharger Lubricating Oil Pumps
Once the oil levels have been checked and topped up if necessary, start the main engine lubricating oil pump and turbocharger lubrication pump. The lubrication system includes pumps and fine filters in duplicate, with one as a standby, to ensure continuous operation. Pre-lubrication pumps supply oil to bearings before engine start-up, reducing boundary lubrication time and minimizing wear on engine components.
Verifying Oil Pressures and Flow for Piston Cooling and Turbochargers
After starting the lubricating oil pumps, verify that the oil pressures and flow rates are within the specified range for piston cooling and turbochargers. Piston cooling is critical for preventing overheating and seizure of the pistons. Proper turbocharger lubrication ensures efficient operation and longevity. The following table outlines typical oil pressures and flow rates for various engine components (for a medium-sized 2-stroke diesel engine):
Engine Component | Oil Pressure (bar) | Oil Flow Rate (L/min) |
Main Bearings | 4-6 | 120-180 |
Piston Cooling | 2-4 | 60-90 |
Turbochargers | 2-3 | 30-50 |
Cooling Water Systems Checks Before Engine Start
Before starting the ship's main engine, it is crucial to perform thorough checks on the cooling water systems. This ensures optimal performance and prevents potential issues. The main engine cooling system is vital for maintaining the engine's operating temperature. It prevents overheating and damage to engine components.
During pre-start checks, consider the continuous circulation of the main engine jackets through a preheater during port stays. This practice prevents the engine from cooling down excessively. Excessive cooling can lead to thermal stress and potential damage when starting the engine. The preheater maintains a consistent temperature, reducing the risk of cold spots and uneven expansion.
Verifying cooling water system pressures is another essential step in pre-start checks. These pressures should be within the specified range, indicating correct system function and no leaks. Any deviations require immediate investigation and resolution to prevent further issues.
The expansion tank, crucial to the cooling water system, must be inspected during pre-start checks. Monitor the water level closely, as a significant decrease may indicate a leakage. Identifying and rectifying leaks before engine start-up is crucial.
Regular monitoring and maintenance of cooling water systems are vital for the ship's main engine longevity and reliability. Comprehensive pre-start checks help identify and address potential problems early. This minimizes the risk of engine failure and ensures smooth operation at sea.
After the engine reaches its correct operating temperature, repeat cooling water system checks. This verifies the system's continued function under normal conditions. Any discrepancies or abnormalities should be addressed promptly to maintain optimal engine performance.
Cooling Water System Component | Pre-Start Check |
Main Engine Jackets | Ensure continuous circulation through preheater during port stay |
System Pressures | Verify pressures are within specified range and no leaks are present |
Expansion Tank | Check water level and monitor for any evident decrease indicating leakage |
Operating Temperature Checks | Repeat cooling water system checks once engine reaches correct operating temperature |
Slow Turning the Engine with Turning Gear
Before starting the main engine, it is crucial to perform a slow turning procedure using the turning gear. The turning gear, operating at a speed of 1 revolution per minute (RPM), moves the crankshaft in small increments. This allows lubricating oil to reach all engine components, including piston rings, cylinder walls, and bearings.
Ensuring Regulating Handles are in Finished with Engines Position
Prior to engaging the turning gear, it is crucial to ensure that the regulating handles display the "Working on Engine" signage. This step is essential to prevent any unintended engine start-up during the slow turning procedure. Properly setting the regulating handles isolates the engine from the propulsion system, facilitating safe maintenance and inspection.
Opening Cylinder Indicator Cocks
Before commencing the slow turning process, all cylinder indicator cocks must be opened. This action allows any residual exhaust gas or other products of combustion (trapped inside the cylinder after shutting the engine) to escape during the turning process. Opening the indicator cocks helps prevent hydraulic lock, which can cause severe damage to the engine components. The slow turning mechanism supplies just enough air for the engine to turn over very slowly. This serves as a precautionary measure against potential damage caused by oil or water leaks into a cylinder.
Turning Engine One Revolution and Checking for Fluid Leaks
With the turning gear engaged, the engine should be turned one complete revolution. During this process, any fluid flowing out of the indicator valves should be carefully monitored and checked. The presence of fluid leaks may indicate issues such as worn piston rings, damaged cylinder liners, or improper sealing of the valves. Identifying and addressing these leaks promptly is essential to maintain the engine's integrity and prevent further damage. Regular use of the turning gear reduces the need for frequent maintenance and repairs that may arise from extended periods of inactivity. This ultimately reduces maintenance costs.
Disengaging and Locking Turning Gear
After the engine has completed a full revolution and any fluid leaks have been resolved, the turning gear must be disengaged and secured in the "OUT" position. This action prevents accidental engagement of the turning gear during engine start-up, which could cause significant damage. Once the turning gear is disengaged, the "Turning Gear Engaged" indicator lamp should turn off, indicating that the turning gear is inactive. Interlocks are installed to prevent engine start if the turning gear remains engaged, ensuring safe operation.
Slow Turning the Engine on Starting Air (Blow Through)
30 minutes prior starting the main engine, a vital procedure called slow turning on starting air, or blow through, is crucial. This step is essential to prepare the engine for a seamless start-up. It also helps identify any potential problems before the engine is fully operational.
Before starting the engine, it is essential to blow it through with air. This process serves two main purposes: first, to expel any residual exhaust gas or other combustion products trapped inside the cylinder after shutting down the engine; and second, to check for any jacket cooling water from the cylinder head, turbocharger, or other sources that may have leaked and collected on top of the piston while the engine was shut down.
If water is expelled from the indicator cock or relief valve during this process, it indicates a leak that must be investigated and rectified before starting the engine. Blowing through the engine is crucial because there have been instances where starting the generator engine from the control room without this step has led to water accumulation on top of the piston, resulting in a bent connecting rod and broken piston. This occurs because water cannot be compressed.
Industry figures show that about 35% of marine engine failures could have been prevented, if the blow through process had been followed. This underlines the critical role of this procedure in averting costly downtime and repairs.
Engine Speed | Blow Through Duration |
Low speed engines (less than 400 rpm) | 30-45 seconds |
Medium speed engines (400-1000 rpm) | 20-30 seconds |
High speed engines (over 1000 rpm) | 10-20 seconds |
Fuel Oil System Checks Before Main Engine Start
Before starting the ship's main engine, it's crucial to perform detailed checks on the fuel oil system. This ensures optimal performance and prevents potential issues. The fuel oil system is vital for delivering fuel to the engine for combustion. Ensuring its components work properly is essential for smooth engine operation.
Checking Fuel Oil Supply and Circulating Pumps
The fuel oil supply pump and circulating pump are key to the system. Before starting the main engine, verify they're working correctly. If the engine had previously stopped on heavy fuel oil, keep the circulating pump and fuel heaters running. This maintains the fuel at the right temperature and viscosity. Ensure the pumps operate at the correct pressures and flow rates as per the manufacturer's guidelines.
Verifying Fuel Oil Pressures, Temperatures, and Flowmeters
Correct fuel oil pressures and temperatures are crucial for efficient combustion and engine performance. Before starting the engine, check the fuel oil pressure gauges to ensure they're within the recommended range. Verify the fuel oil temperature, as it impacts fuel viscosity and atomization.
Also, check fuel oil flowmeters for proper functioning and note their counters to monitor fuel consumption.
With respect to diesel fuel, the ease of cold engine starting depends on the ignition quality of the fuel. Centistokes (cSt) is a unit for measuring viscosity, a fuel property.
Additional fuel oil system checks include:
Inspecting fuel oil filters for cleanliness and replacing if necessary
Checking fuel oil tank levels and replenishing if required
Ensuring proper operation of fuel oil valves and quick-closing valves
Verifying the functionality of fuel oil system alarms and safety devices
By conducting these checks before starting the main engine, potential issues can be identified and addressed early. This minimizes the risk of engine failure or damage. Regular maintenance and monitoring of the fuel oil system components ensure reliable and efficient operation of the ship's main engine.
Miscellaneous Checks Before Main Engine Start-up
Before starting the ship's main engine, it is crucial to conduct a series of miscellaneous checks. These checks ensure the smooth and safe operation of the vessel. They involve verifying engine instrumentation readings, inspecting the scavenge air receiver, checking box drains and test cocks, examining the engine top bracing system, and monitoring thrust bearing temperature, lube oil pressure, and vibration dampers.
Verifying Engine Instrumentation Readings
All engine instrumentation readings need to be checked, prior starting the engine. This includes checking gauges, meters, and sensors that monitor various parameters such as temperatures, pressures, and speeds. Any malfunctioning instruments should be promptly identified and replaced to ensure accurate monitoring of the engine's performance.
Checking Scavenge Air Receiver, Box Drains, and Test Cocks
The scavenge air receiver plays a vital role in the engine's operation by supplying clean air to the cylinders. Before starting the engine, the scavenge air receiver and box drains should be open to allow any accumulated moisture or debris to be expelled. Additionally, the test cocks should be closed to prevent any unintended air leakage.
Inspecting Engine Top Bracing System
The engine top bracing system provides structural support to the engine and helps maintain its alignment. A thorough inspection of the bracing system should be conducted to ensure that it is properly secured and in good condition. Any loose or damaged components should be promptly addressed to prevent potential engine damage or misalignment.
Checking Thrust Bearing Temperature, Lube Oil Pressure, and Vibration Dampers
The thrust bearing is a critical component that absorbs the axial forces generated by the propeller. Before starting the engine, the thrust bearing temperature should be within the specified range, and the lube oil pressure should be at the correct level. Additionally, the axial and torsional vibration dampers should be checked to ensure they have adequate lube oil pressure to function effectively in reducing engine vibrations.
Component | Check | Importance |
Engine Instrumentation | Verify readings and replace malfunctioning instruments | Ensures accurate monitoring of engine performance |
Scavenge Air Receiver | Open box drains and close test cocks | Allows moisture and debris expulsion, prevents air leakage |
Engine Top Bracing | Inspect for proper securement and condition | Maintains engine alignment and prevents damage |
Thrust Bearing | Check temperature and lube oil pressure | Ensures proper absorption of axial forces |
Vibration Dampers | Verify adequate lube oil pressure | Reduces engine vibrations for smooth operation |
Normal Operation Checks for Running Main Engines
Regular checks are vital for the optimal performance of a ship's main engine. These normal operation checks focus on monitoring key parameters, comparing cylinder readings, and ensuring safety devices work correctly.
Regularly Checking System Pressures and Temperatures
Checking system pressures and temperatures is a crucial task. Engineers must compare these readings with commissioning records, considering engine speed and power. Key parameters to monitor include:
Lubricating oil pressure and temperature
Cooling water pressure and temperature
Fuel oil pressure and temperature
Charge air pressure and temperature
Exhaust gas temperature
Monitoring these parameters helps engineers spot deviations early, preventing engine damage.
Comparing Cylinder Mean Indicated Pressure, Compression Pressure, and Maximum Combustion Pressures
Comparing cylinders is another key aspect of normal operation checks. Engineers should analyze mean indicated pressure, compression pressure, and maximum combustion pressures for each cylinder. This helps identify issues like worn piston rings or leaking valves. The below table summarizes average values for a typical & medium-sized 2-stroke main engine:
Cylinder | Mean Indicated Pressure (bar) | Compression Pressure (bar) | Maximum Combustion Pressure (bar) |
1 | 18.5 | 110 | 150 |
2 | 18.2 | 108 | 148 |
3 | 18.7 | 112 | 152 |
4 | 18.4 | 109 | 149 |
Monitoring Oil Mist Detector Operation
The oil mist detector is crucial for monitoring the crankcase atmosphere for oil mist, indicating potential bearing failure. Engineers must ensure it's working correctly and respond to alarms. Regular testing and calibration are also necessary.
Checking Shut-off Valves in Cooling and Lubricating Systems
Engineers should verify shut-off valves in cooling and lubricating systems are in the correct position. These valves control coolant and lubricating oil flow to engine components. Correct positioning is vital for maintaining proper temperatures and preventing damage. Any incorrect positions should be fixed immediately.
Regular checks of the system and engine pressures and temperatures are essential during normal running, providing valuable data for estimating engine performance.
Ship Main Engine Starting Mechanisms: Electrical Controls and Automation
Modern ships now feature advanced electrical controls and automation for starting and managing the main engine. This allows Bridge Officers to control the propeller's direction and speed from the bridge. The main engine control system includes equipment on the bridge, engine control room (ECR), and near the engine. Together, they ensure safe and efficient operation.
The engine control room is where remote control equipment resides. It includes signaling, alarm, and control facilities, along with electronic modules. Key modules like the engine starting and reversal logic module and the digital/analog engine RPM converter are essential. They process signals and execute commands to control the main engine precisely.
On the bridge, an engine telegraph and an automatic control panel facilitate smooth engine operations. The bridge crew can start the main engine automatically, following a specific sequence. This includes positioning the cam shaft, admitting starting air and fuel, adjusting speed, and monitoring safety. This level of remote control boosts navigation efficiency and allows for quick adaptation to changing conditions.
Parameter | Monitoring Purpose |
Lube Oil Temperature | Ensuring proper lubrication and preventing overheating |
Jacket Cooling Water Temperature | Maintaining optimal engine temperature |
Exhaust Gas Temperature | Detecting abnormalities and monitoring engine performance |
Lube Oil Pressure | Confirming adequate lubrication and detecting leaks |
Jacket Cooling Water Pressure | Ensuring proper cooling system functioning |
Fuel Oil Pressure | Maintaining consistent fuel delivery to the engine |
Fuel Oil Flow | Monitoring fuel consumption and detecting irregularities |
During operation, various parameters are continuously monitored to ensure optimal performance and detect anomalies. These include lube oil, jacket cooling water, and exhaust gas temperatures, as well as pressures of lube oil, JCW, and fuel oil. Fuel oil flow is also monitored to track consumption and identify irregularities. This allows the engine protection system to promptly address potential issues, preventing damage and ensuring reliable operation.
The advent of advanced electrical controls and automation systems has revolutionized ship main engine starting mechanisms, enhancing safety, efficiency, and reliability in marine propulsion.
The increasing adoption of automatic control systems in ships is driven by the need to reduce manning levels. An increase in UMS (Unattended Machinery Space) ships, qualified for safe operation without constant human monitoring is on the rise the past couple of decades.
Conclusion
Starting a ship's main engine is a complex task that demands careful attention to various systems and components. Ensuring safe and efficient operation is paramount. Regular maintenance checks and inspections are vital to prevent breakdowns and maintain peak performance. By thoroughly preparing the engine, including the air, lubricating oil, cooling water, and fuel oil systems, the risk of issues is significantly reduced, enhancing safety.
Keeping an eye on the engine during regular operation is vital for maintaining peak performance and identifying potential issues early. Consistent evaluations of system pressures, temperatures, and other key parameters ensure the main engine stays within its intended limits. It's important to observe cylinder mean indicated pressure, compression pressure, and peak combustion pressures. Moreover, inspecting the oil mist detector and shut-off valves in cooling and lubricating systems is crucial.
The evolution of electrical controls and automation has transformed the main engine starting process. It has made the process more streamlined, reliable, and efficient. These technological advancements have simplified the starting procedure and boosted the safety and efficiency of ship operations.
FAQ
What are the most common starting systems for marine diesel engines?
Marine diesel engines often use air, electric, or hydraulic start systems. Air start systems rely on compressed air to spin the engine's crankshaft. Electric start systems use strong electric motors for the same purpose. Hydraulic start systems employ high-pressure fluid to turn the engine.
What checks should be performed on the lubricating oil system before starting the main engine?
Before the main engine starts, check and top off the oil in the main engine sump if needed. Start the lubricating oil pump and the turbocharger lubricating oil pump. Verify all oil pressures are within the acceptable range. It's crucial to ensure the oil flows well for piston cooling and turbochargers.
Why is slow turning the main engine with the turning gear important?
Slow turning prevents damage from fluid leaking into cylinders. Begin by setting the regulating handles to "Finished with Engines" and opening all cylinder indicator cocks. Then, turn the engine once with the gear, checking for any fluid at the indicator valves.
What is the purpose of slow turning the main engine on starting air (blow through)?
The "blow through" involves slow turning the engine with starting air in the last 30 minutes before starting. As it turns, check for fluid at the indicator cocks. This ensures cylinders are free of fluids before engine start.
What are the key components of a ship's main engine control system?
The control system includes bridge, engine control room (ECR), and locally mounted equipment. Electronic modules, local equipment, and bridge tools work together. They ensure the main engine operates safely and efficiently, supporting automatic remote control and protecting the diesel engines.
What regular checks should be performed during normal operation of the main engine?
Regularly monitor system pressures and temperatures, comparing them to commissioning records. Consider engine speed and power. Check cylinder mean indicated pressure, compression pressure, and maximum combustion pressures across cylinders. Ensure the oil mist detector operates correctly and verify shut-off valves in cooling and lubricating systems are in the right position.
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