Patent Document ID: 20040019436
Application ID: 10460579
Patent Flag: 0

Claim One:
1. A method of determining the nitrogen concentration in a natural gas whose carbon dioxide concentration is known, comprising the steps of: modeling the product of the natural gas density times its specific heat (at constant volume) divided by its molecular weight as a function of the standard speed of sound of the gas, the carbon dioxide concentration, and the nitrogen concentration, for a number of gas mixtures; determining constant values for an equation representing the function; heating a sample of the natural gas in a closed container having a known volume; measuring the heat energy to raise the temperature of the natural gas a known temperature increment; equating the product of the natural gas density times its specific heat (at constant volume) divided by its molecular weight to the heat energy divided by the product of the volume times the temperature increment, thereby obtaining a model equation; and substituting known values into the model equation to solve for the nitrogen concentration.