LNG TankerA scale profile of a Norwegian tanker is shown. Its capacity (with all five of its spherical tanks completely full) is 128,000 cubic meters of liquid natural gas (LNG).
Some densities of LNG are:
[ρLNG(1 atm, -162°C) = 422 kg/m3; ρmethane(1 atm, 25°C) = 0.66 kg/m3].
Use the information given to calculate the fully-loaded mass of LNG.
♦ Mass, density and volume are related as: m = ρ V. The hold volume and density of the liquid, LNG, are provided, hence:
This fuel is not sold by kilogram of liquid. It is sold by the number of its "standard cubic foot." The pressure of a SCF is one atmosphere and its temperature is 25°C. Some call this condition the standard state.
Calculate the number of SCF of natural gas the tanker delivers.
♦ The mass, density volume relation applies: m = ρ V
Estimate the length of the tanker.
♦ A first step is to calculate the diameter of the identical spherical tanks using the volumetric capacity and the formula for the volume of a sphere.
A ruler might used to measure the length. We used a graphics software to scan the tanker profile. The scan was then adjusted by moving the spheres to eliminate the space between them. Finally the software was set to display a grid over the image.
A count of grid units of the width of the 5 spheres yielded 204 units, meaning the diameter of each sphere is 40.8 units. But we have already determined that the spheres are 36.6 meters in diameter. Hence the scale is that each grid unit represents 0.9 meters. The count of the grid units in the full length of the tanker image is 316 units. Thus 313 units x ( 0.9m / unit) = 283 meters.
Estimate the beam of the ship.
♦ The beam of the ship is its widest width. The tanker must be at least as wide as the diameter of one sphere. That would be 36.6 meters. But the beam measurement would also include two "thicknesses" of the hull. Estimate the hull thickness to be 2 meters then the beam of the tanker would be approximately 40.6 meters.