What is a Marine Boiler?
A Marine boiler is a closed vessel in which fluid, typically water, is heated to create hot water or steam. This heated fluid is then used in various processes or heating applications.
How does a Marine Boiler Produce Steam?
Boilers burn fuel to heat water. As water absorbs heat, it boils and turns into steam at a specific pressure, which is then used for various applications.
Why do we use Marine boiler on ship?
Ships use steam for various purposes, including:
- Fuel Oil Heating: As you mentioned, heavy fuel oil needs to be heated to a specific viscosity for efficient burning in the ship’s engine. Steam coils or heat exchangers warm the fuel, making it flow more easily and ensuring proper atomization for combustion.
- Steam Turbines: Many ships, particularly older ones, use steam turbines for propulsion. The high-pressure steam spins turbine blades, which are connected to a shaft that rotates the propeller.
- Cargo Handling: Steam turbines can also power pumps used for loading and unloading cargo, especially on tankers where heavy oil needs efficient transfer.
- Deck Machinery: Steam can be used to operate winches, cranes, and other deck equipment involved in cargo handling and anchoring.
- Hot Water Heating: Steam is a great way to heat large quantities of water for showers, laundry, and galley operations.
- Air Conditioning: Though less common today, steam can be used to drive absorption chillers for air conditioning, particularly in older vessels.
- Firefighting: Some ships utilize high-pressure steam for firefighting. The steam can displace oxygen, smothering flames and helping to extinguish fires.
Types of Marine Boilers on Ships:
There are two main types of marine boilers:
- Fire Tube Boilers
- Water Tube Boilers
Fire Tube Boilers
In a fire tube boiler, hot combustion gases generated by burning fuel travel through tubes enclosed within a shell filled with water. The heat from the gases transfers through the tube walls, heating the surrounding water and eventually converting it into steam.
- Advantages:
- Lower initial cost compared to water tube boilers.
- Simpler design with fewer control systems, making them easier to operate.
- Disadvantages:
- The drums containing the water are exposed to high heat, potentially increasing the risk of explosions if not properly maintained.
- The large water volume can hinder circulation efficiency.
- Steam pressure and evaporation capacity are limited compared to water tube boilers.
Also Read :- What is Exhaust Gas Boiler or Economizer on Ship?
Water Tube Boilers
In contrast to fire tube boilers, water tube boilers circulate water through tubes within a furnace chamber. The hot combustion gases from burning fuel surround these tubes, transferring heat directly to the water inside.
- Advantages:
- Faster heat transfer and quicker response to steam demand fluctuations.
- Higher steam production efficiency.
- Generally considered safer due to the smaller volume of water under pressure.
- Disadvantages:
- Require more complex controls and operational procedures compared to fire tube boilers.
- Typically have a higher initial cost.
Fire Tube vs. Water Tube Boilers: Understanding the Differences
Boilers heat water to produce steam for various industrial and commercial applications. Two main boiler designs exist: fire tube and water tube. Each has distinct characteristics that make it suitable for specific needs.
boiler mountings or boiler fittings.
These are essential components that are directly attached to the boiler shell to ensure its safe and efficient operation.
Here’s a breakdown of the specific functions of some key boiler mountings you mentioned:
- Safety Valve: This valve is critical for safety. It releases excess pressure from the boiler if it builds up beyond a safe limit, preventing potential explosions.
- Main Steam Stop Valve: This valve controls the flow of steam out of the boiler entirely. It can be opened or closed to regulate steam supply to various applications.
- Air Vent Cock: This allows air trapped inside the boiler to be released during the filling process. Air can hinder boiler efficiency and needs to be vented before steam generation.
- Gauge Glass Level Indicators: These are transparent glass tubes that allow visual confirmation of the water level inside the boiler. Maintaining the proper water level is crucial for safe and efficient operation.
- Feed Check Valve: This one-way valve allows water to enter the boiler but prevents backflow of water out of the boiler.
- Blowdown Valves (Scum Blowdown and Bottom Blowdown): These valves are used for periodic cleaning of the boiler.
- Scum Blowdown: Located at the water surface, it allows removing accumulated impurities like scum or sludge that can float on the water’s surface.
- Bottom Blowdown: Situated at the lowest point of the boiler shell, it helps remove sediment that settles at the bottom and can reduce boiler efficiency.
- Salinity Cock or Test Cock: This valve allows for collecting a water sample to measure its salinity or dissolved salt content. Monitoring salinity helps prevent corrosion and other water quality issues within the boiler.
- Manhole Doors: These are large openings that provide access to the inside of the boiler for inspection, cleaning, and maintenance.
By having these boiler mountings properly installed and maintained, you can ensure the safe, efficient, and reliable operation of your boiler system.
