LNG Tank Density

Inputs

Input	Description
Name of Methane	Column from the Component Table (Xm)
Name of Nitrogen	Column from the Component Table (Xn)
Molecular Weight	Column from the Component Table (in any Molecular Weight UOM (MWi)
Temperature	Attribute (in any Temperature UOM) (T)
Component Mole Fraction	Attribute (DataTable) (Xi)
Molar Volume Table (MVi)	Molar volume table
Volume Reduction Table (k1)	Volume reduction table k1
Volume Reduction Table (k2)	Volume reduction table k2

Calculations

Example

1. Calculate ∑ (Xin*MWi).

2. Calculate Vi - Molar volume at specific temperatures as known for each component. For a given temperature, molar volume of the component is calculated by interpolation.

3. Calculate ∑ (Xi*MVi).

4. k1 and k2 are calculated by interpolation from Standard Tables based on the molecular weight of each component and Temperature.

5. Use the above Density formula to calculate Density.

   Comp/Temp	-170	-166	-162	-160	-158	-154	-150
   Methane (CH4 -	0.036890	0.037375	0.037884	0.038148	0.038419	0.038983	0.039579
   Ethane (C2H6) -	0.047116	0.047442	0.047774	0.047942	0.048111	0.048455	0.048805
   Propane (C3H8) -	0.061602	0.061957	0.062316	0.062497	0.062678	0.063045	0.063417
   Iso-Butane (iC4H10)	0.077356	0.077751	0.078151	0.078352	0.078554	0.078962	0.079374
   n-Butane (nC4H10)	0.075926	0.076303	0.076684	0.076875	0.077068	0.077456	0.077847
   Iso-Pentane (iC5H12)	0.090641	0.091071	0.091504	0.091721	0.091939	0.092377	0.092817
   n-Pentane (nC5H12)	0.090535	0.090953	0.091373	0.091583	0.091794	0.092217	0.092643
   n-Hexane (C6H14)	0.103800	0.104236	0.104677	0.104890	0.105122	0.105570	0.106020
   Nitrogen (N2)	0.041779	0.043543	0.045702	0.046995	0.048488	0.051192	0.055877
   Carbon Dioxide (CO2)	0.026400	0.023700	0.027000	0.027200	0.027300	0.027650	0.027950
   Oxygen (O2)	0.029800	0.030450	0.031150	0.031510	0.031910	0.032750	0.033670

   Linear interpolation is used to calculate the molar volume at any temperature in the range of -170°F to -150°F. For example, let use say we need to calculate Vi at -160.1°F:

   Similarly, volume correction factor k1 and k2 are also obtained by interpolation.