Augmented Raman analysis of a gas mixture
The present disclosure includes discloses a method for analyzing a multi-component gas sample using spectroscopy in combination with the measurement of extrinsic or intrinsic properties of the gas sample. The results of the spectroscopic analysis and the measurement are combined to quantify a gas component unseen by the spectroscopic analysis.
1. A method for analyzing the composition of a multi-component gas sample, comprising:
determining a first composition of a multi-component gas sample using a spectroscopic device;
calculating a relative composition matrix containing a normalized molar amount of each component of the multi-component gas sample, based on the first composition;
calculating an average molar mass of the relative composition matrix using a molar mass and the normalized molar amount of each component of the relative composition matrix;
measuring a temperature, a pressure, and a density of the gas sample and calculating an inverse compressibility factor of the gas sample therefrom;
calculating a molar amount of a spectroscopic-invisible gas using the average molar mass, the inverse compressibility factor, and a molar mass of the spectroscopic-invisible gas;
adding the molar amount of the spectroscopic-invisible gas to the relative composition matrix; and
adjusting the normalized molar amount of each component in the relative composition matrix to account for the molar amount of the spectroscopic-invisible gas.
2. The method of claim 1 , wherein the spectroscopic device is a Raman spectroscopic device and spectroscopic-invisible is defined as invisible to Raman spectroscopy.
3. The method of claim 1 , wherein the spectroscopic device is a near infrared/infrared absorption spectroscopic device and spectroscopic-invisible is defined as invisible to near infrared/infrared absorption spectroscopy.
4. A method for analyzing the composition of a multi-component gas sample, comprising:
determining a first composition of a multi-component gas sample using a spectroscopic device;
calculating a relative composition matrix containing a normalized molar amount of each component of the multi-component gas sample, based on the first composition;
measuring a temperature, a pressure, and a density of the gas sample and calculating a first compressibility factor of the gas sample therefrom;
estimating a molar amount of a spectroscopic-invisible gas;
adding the estimated molar amount of the spectroscopic-invisible gas to the relative composition matrix;
adjusting the normalized molar amount of the other components in the relative composition matrix to account for the estimated molar amount of the spectroscopic-invisible gas;
calculating a second compressibility factor of the gas sample using the relative composition matrix;
determining whether a difference between the first compressibility factor and the second compressibility factor exceeds a threshold, wherein upon determining that the difference exceeds the threshold:
adjusting the estimated molar amount of the spectroscopic-invisible gas in the relative composition matrix such that the difference between the first compressibility factor and the second compressibility factor is reduced;
repeating the adjusting of the normalized molar amount of each component in the relative composition matrix, the calculating a second compressibility factor, and the determining whether a difference between the first compressibility factor and the second compressibility factor exceeds the threshold until the difference does not exceed the threshold.
5. The method of claim 4 , wherein the spectroscopic device is a Raman spectroscopic device and spectroscopic-invisible is defined as invisible to Raman spectroscopy.
6. The method of claim 4 , wherein the spectroscopic device is a near infrared/infrared absorption spectroscopic device and spectroscopic-invisible is defined as invisible to near infrared/infrared absorption spectroscopy.