Chp 8 (LNG)

The costs of building a liquefied natural gas plant are typically high relative to comparable energy projects. This is due to:

• large amounts of cryogenic material required

• strict design and safety standards

• historic tendency to over design

• all above

The Boil Off Gas (BOG) is the continuously evaporated causes the pressure inside the tank to reduce which changes the quality of LNG over

• True
• False

Which of the following statement is Not True regarding on the flat bottom tank?

• The difference between single, double and full containment flat bottom tank is in the method of secondary containment
• The full containment roof is made of materials that can handle cryogenic temperatures, and if the inner tank leaks, all liquids and vapors are still contained within the outer wall and roof
• For double containment, the inner and outer shell contain liquid and vapor
• For a single containment, inner shell contain liquid and vapor

Which of the following sketch and labels of flat bottom tank is Not True?

• 
• 
• 

The inner and outer shell contains liquid & vapour.

Which type of flat bottom LNG storage containment refers to?

The secondary container in double containment storage is intended to contain any vapour resulting from the leakage

• TRUE

• FALSE

Which of the following safety aspect is True in designing and operating LNG?

• Suitable material and insulation to withstand high temperature
• Maximum liquid level to accommodate Vapor due to boiling
• Design at maximum load and withstand inner pressure
• Design to withstand material contraction at high pre

Which of the following statement is not true regarding on the Rollover Phenomenon? (select more than one)

• rapid release of LNG vapour that resulted of the spontaneous mixing of layers of same densities of LNG in a storage or cargo tank.

• LNG of different densities can be formed during filling an LNG tank with LNG of different densities

• The spontaneous mixing of layers of different densities of LNG in a storage is referred to as stratification

• The lighter fractions will boil off first, resulting in the density of the remaining liquid gradually decreased

The following diagram shows the free convection circulation in LNG tank. Choose the correct statement that describe the process.

• 1. (3) evaporation at the surface that remove heat and lighter components

• (2) warm LNG become heavier and rises

• (4) cooler and heavier LNG falls

• 1. (1) heat passing into the tank from atmosphere

A key indicator that stratification has occurred is a noticeable depletion in the normal boil-off rate.

• TRUE

• FALSE