LNG Ships: Technical Overview
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Questions and Answers

What is Boil Off Gas primarily used for in LNG carriers?

  • Cooling systems
  • Fuel for propulsion (correct)
  • Cargo storage
  • Maintenance

Low-pressure 2 stroke Dual Fuel engines are currently the least favored type for LNG propulsion.

False (B)

Name one of the two major manufacturers that dominate the LNG engine market.

MAN Energy Solutions or WinGD

Most LNG carriers use their cargo as fuel, which is called _____ Gas.

<p>Boil Off</p> Signup and view all the answers

Match the LNG propulsion engine manufacturers with their respective engine models:

<p>MAN Energy Solutions = ME-GI/ME-GA WinGD = X-DF</p> Signup and view all the answers

What is a key characteristic of Type C tanks?

<p>They meet pressure vessel standards and are self-supported. (C)</p> Signup and view all the answers

C-type tanks are commonly used across LNG and Pressurized LPG vessels.

<p>True (A)</p> Signup and view all the answers

What material is generally used for the construction of Type C tank bodies?

<p>Low-temperature resistant materials</p> Signup and view all the answers

The first domestic LNG carrier using C-type independent liquid cargo tank was delivered by __________ in 2015.

<p>Jiangnan Shipyard</p> Signup and view all the answers

Match the following characteristics with Type C tanks:

<p>Pressure-resistant = Meets pressure vessel standard Design = Cylindrical or spherical with no internal structure Common use = Small and medium-sized LNG carriers Insulation = Covered with insulating materials</p> Signup and view all the answers

Which type of containment is adapted from LPG containment for LNG?

<p>Type A (D)</p> Signup and view all the answers

What is a primary advantage of membrane tanks in LNG carriers?

<p>High capacity utilization (D)</p> Signup and view all the answers

Moss spherical tanks have better volume utilization than membrane tanks.

<p>False (B)</p> Signup and view all the answers

Membrane tanks provide efficient space usage compared to spherical tanks.

<p>True (A)</p> Signup and view all the answers

What material is predominantly used in the construction of Type A tanks?

<p>aluminum</p> Signup and view all the answers

What is the primary construction material of Type B LNG tanks?

<p>Aluminium alloy (D)</p> Signup and view all the answers

What unique design feature does the TGZ MARK III include to manage thermal contraction?

<p>waffle pattern</p> Signup and view all the answers

Type A tanks utilize ______ materials in the insulation.

<p>low-density foam</p> Signup and view all the answers

What is a benefit of Type A tanks in terms of liquid motion?

<p>They have no sloshing issues. (D)</p> Signup and view all the answers

The __________ feature of membrane tanks helps in continuous monitoring for leaks.

<p>double membrane</p> Signup and view all the answers

Type A tanks currently have no competitors in the LNG carrier market.

<p>False (B)</p> Signup and view all the answers

Match the advantages of membrane tanks with their descriptions:

<p>High Capacity Utilization = Maximizes cargo space Lightweight = Reduces vessel weight Leak Detection = Uses double membrane system Efficient Space Usage = Adapts to ship structure</p> Signup and view all the answers

Match the following types of LNG tank classifications with their descriptions:

<p>Type A = Independent self-supporting prismatic containment system Moss = Spherical design allowing for flexibility Membrane = Thin-walled containment system Type B = Pressure vessels designed for safety</p> Signup and view all the answers

What is the primary safety feature of spherical Type B LNG tanks?

<p>High degree of safety against fracture or failure</p> Signup and view all the answers

Type A tanks have similar flexibility to Moss spherical tanks.

<p>True (A)</p> Signup and view all the answers

Which of the following is noted as a consideration for operating an LNG carrier with a membrane tank?

<p>Thermal Contraction Management (A)</p> Signup and view all the answers

The main purpose of the void spaces between the inner hull and outer hull in LNG carriers is for ______.

<p>ballast</p> Signup and view all the answers

Regular maintenance and inspection are unnecessary for membrane tanks.

<p>False (B)</p> Signup and view all the answers

Which type of LNG tank is described as 'largely out of date and uncommon'?

<p>IHI Prismatic (B)</p> Signup and view all the answers

What is the primary factor affecting the insulation efficiency of Type A tanks?

<p>thermal conductivity</p> Signup and view all the answers

What type of monitoring system is included in designs like GT96 to detect hydrocarbon leaks?

<p>nitrogen flushing system</p> Signup and view all the answers

Insulation in Type B tanks is necessary to minimize boil-off.

<p>True (A)</p> Signup and view all the answers

Match the LNG tank types with their features:

<p>Type A = Only 1 carrier currently exists Type B = Spherical tanks made of aluminium alloy Membrane = Containment of choice for efficiency and capacity IHI Prismatic = Largely out of date</p> Signup and view all the answers

What structural feature supports the weight of Type B LNG tanks?

<p>Metal skirt</p> Signup and view all the answers

What is the DWT of the LNG Rosenrot?

<p>98,936 DWT (B)</p> Signup and view all the answers

The LNG Rosenrot was built in 2020.

<p>False (B)</p> Signup and view all the answers

The LNG Rosenrot has a beam of ______ meters.

<p>47.9</p> Signup and view all the answers

What does 'heel' refer to in LNG tanker operations?

<p>The small quantity of cargo remaining in the tanks (D)</p> Signup and view all the answers

LNG carriers primarily operate on laden or ballast voyages.

<p>True (A)</p> Signup and view all the answers

The LNG Rosenrot is classified as a ______ carrier.

<p>LNG</p> Signup and view all the answers

Match the following specifications with their correct descriptions:

<p>LOA = Length Overall of the ship Beam = Width of the ship DWT = Deadweight tonnage BHP = Brake Horse Power of the engines</p> Signup and view all the answers

Flashcards

Moss-Rosenberg Type B LNG Tank

A type of LNG carrier tank that features spherical tanks made of aluminum alloy and designed to carry LNG close to atmospheric pressure. The tanks are protected by void spaces and situated in a line from the bow to the stern.

Type B LNG Containment System

A type of LNG cargo containment system that utilizes independent spherical tanks made from aluminum alloy. The tanks are located within void spaces, providing protection in case of accidents.

Membrane (Integrated) LNG Tank

A type of LNG cargo containment system that employs tanks built with a membrane-like structure. These tanks offer high efficiency and are a popular choice for LNG carriers due to their capacity.

IHI Prismatic LNG Tank

A type of LNG carrier tank that utilizes a prismatic design for the tanks. This design is considered outdated and less common compared to other designs.

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High Capacity Utilization

Membrane tanks can be shaped to fit the ship's hull, maximizing cargo space.

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Efficient Space Usage

Membrane tanks conform to the ship's structure, making better use of available space compared to spherical tanks.

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Lightweight

Thin membrane and insulation layers reduce the overall weight of the structure, potentially improving fuel efficiency.

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Thermal Contraction Management

The membrane must withstand significant thermal contractions as the LNG is cooled to cryogenic temperatures.

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TGZ MARK III Design

Designs use a 'waffle pattern' to absorb thermal contractions.

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Leak Detection

Continuous monitoring for leaks is crucial.

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GT96 Design

Double membrane with a layer of nitrogen flushing between them to detect hydrocarbon leaks.

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Maintenance and Inspection

Regular inspection and maintenance are essential to ensure the integrity of the membrane and insulation layers.

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What is a Type C LNG tank?

A type of LNG tank that is independent, self-supported, and pressure-resistant. It's built to meet pressure vessel standards.

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Describe the physical features of a Type C tank.

Type C tanks are cylindrical or spherical, made of materials that resist low temperatures, and have minimal internal structure. They are often covered with insulation.

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What is a key advantage of Type C tanks?

Type C tanks are easier and less expensive to build compared to other LNG containment systems.

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On what type of LNG vessels are Type C tanks prevalent?

Type C tanks are commonly used on smaller and medium-sized LNG carriers.

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What is an example of a Type C tank system and where was it used?

The German TGE cargo containment system is an example of a Type C tank and was used in the world's largest C-type LNG carrier.

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LNG Carrier Classification

LNG carriers are classified based on their containment type, with each type offering distinct advantages and characteristics.

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Moss and Membrane Vessels

Moss and Membrane are prominent types of LNG tank classifications, each with its unique design and functionality.

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Type A LNG Tank

Type A tanks are a modified version of LPG containment systems, specifically designed for LNG. They are self-supporting, prismatic, and made of aluminum.

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Advantages of Type A Tanks

Type A tanks offer flexibility in filling levels, similar to Moss spherical tanks. They also provide better volume utilization compared to membrane tanks.

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Insulation in Type A Tanks

Type A tanks leverage low-density foam materials in insulation, resulting in better insulation thickness and density for reduced boil-off rates.

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Moss Spherical Tanks

Moss tanks are spherical, independent, and made of steel. They are known for their exceptional strength and high volume efficiency.

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Boil Off Gas (BOG)

The natural evaporation of LNG cargo due to temperature changes.

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Membrane Tanks

Membrane tanks are flexible, thin-walled, and typically made of stainless steel. They conform to the ship's hull and are known for their lightweight and efficient design.

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Advantages of Membrane Tanks

Membrane tanks are preferred for smaller ships and offer advantages in terms of adaptability and weight efficiency.

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Dual Fuel Engine

A type of propulsion system that uses both LNG and diesel fuel, allowing for flexibility and emissions reduction.

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Low-Pressure 2-Stroke Dual Fuel Engine

A two-stroke engine designed to operate on low-pressure LNG fuel, commonly used in LNG carriers and other LNG-fueled vessels.

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MAN Energy Solutions

A leading engine manufacturer specializing in low-pressure 2-stroke dual fuel engines for LNG propulsion.

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WinGD (owned by Wartsila)

A major engine manufacturer known for its X-DF engines, which are designed for low-pressure LNG propulsion.

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Cap 98%

The amount of cargo a vessel can carry at 98% capacity.

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Cap 100%

The amount of cargo a vessel can carry at 100% capacity.

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M/E Type

The type of engine used in a vessel.

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BWTS

A system that treats ballast water to prevent the spread of invasive species.

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X-DF

A type of LNG carrier with a specific design for fuel efficiency.

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Conditioning

Indicates the cargo tanks are in the process of being cooled down and prepared for loading, while the vessel may be in ballast.

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Heel

A small amount of cargo remaining in the tanks, serving as fuel and keeping the tanks cold for the next loading.

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Conditioning for Dry Dock

The process of preparing the cargo tanks for dry docking, usually after a cargo discharge and before any new loading.

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Study Notes

LNG Ships: Technical and Operational Intro

  • LNG ship operation involves laden or ballast voyages
  • Cargo tanks remain conditioned for cargo throughout this time
  • Heel (ballast): small quantity of cargo left in tanks for cooling and continued use as fuel
  • Some cargo tanks are also used as fuel tanks
  • LNG vessels need a dry dock process to transition between cargo cycles

LNG Vessel Classification

  • LNG vessels can be classified based on containment type
  • Vessels can have Independent tanks, or Integral tanks
    • Independent tanks (Type A or B): Classified based on pressure (p<700 mbar, p>2000 mbar) and secondary barrier type (Full or Partial).
      • Type A: Independent, self-supporting, prismatic, aluminum tanks
      • Type B: Independent, spherical, or cylindrical tanks
    • Integral tanks (Type C): Commonly used, cheaper option, cylindrical or spherical

LNG Containment Types: A, B, and C

  • Type A: Independent, self-supporting, prismatic containment with low-density foam for insulation.
  • Type B: Moss-Rosenberg type, independent, spherical, tanks.
  • Type C: Independent, cylindrical or spherical tanks using low-temp materials, insulated
  • LNG carriers use various containment systems for shipping and storing LNG
  • Membrane (integrated) tanks are also a popular choice

LNG Propulsion

  • LNG carriers often reuse their cargo as fuel in a process called BOIL OFF GAS (BOG)
  • Low-pressure, two-stroke dual-fuel engines are common in modern LNG carriers.
  • Makers in this space include MAN Energy Solutions and WinGD

Operation Considerations

  • Thermal contraction management is crucial during cryogenic temperatures
  • Leak detection systems are in use to monitor for leaks
  • Maintenance and inspection are essential, any damage could compromise the containment system

Additional Notes

  • The presentation highlights various types of LNG carriers and the associated technology.
  • Key factors such as tank containment systems, propulsion types, operation and maintenance are presented.

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LNG Shipping Introduction PDF

Description

Explore the technical and operational aspects of LNG ships, including their classification and containment types. Understand the significance of ballast voyages and the role of cargo tanks in LNG vessel operations. This quiz provides essential insights into the field of maritime engineering.

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