Improved Sensitivity of Natural Gas Infrared Measurements Using a Filling Gas

Abstract

European trends to get greener cities and protect the environment imply substituting traditional diesel/gasoline engines for gas (gas-hybrid) powered engines. To accomplish this, straightforward quality control of liquefied and/or compressed natural gas is needed. This communication shows that the broadening effect of an auxiliary inert gas (Ar) enhances their infrared (IR) gaseous spectra and improves usual analytical performance parameters by 50%, which paves the way to use IR routinely to assess the composition of natural gas samples.

New Ways for the Advanced Quality Control of Liquefied Natural Gas

“…The operational procedure when dealing with a broadening gas is not difficult and we found nice results considering the next steps [38]: (i) purge the cell with the filling gas (0.5 bar, 1 min); (ii) record background; (iii) purge with a small flow of the sample gas; (iv) Finally, apodization is a mathematical operation applied after the Fourier transform that minimizes the appearance of secondary peaks at both sides of the actual peak [34]. For natural gas analysis, medium-strong functions, such as Happ-Genzel or Beer-Norton, are used commonly.…”

“…The operational procedure when dealing with a broadening gas is not difficult and we found nice results considering the next steps [38]: (i) purge the cell with the filling gas (0.5 bar, 1 min); (ii) record background; (iii) purge with a small flow of the sample gas; (iv) fill the cell with the sample (0.2 bar), and, then, add the broadening gas until a total pressure of 1.5 bar; and (v) record spectra.…”

“…In previous studies [38] a suite of inert gases (N 2 , He, and Ar) was evaluated to determine which improves most the sensitivity of selected weak bands when measuring commercial LNG samples. Out of them, Ar arose as the most adequate one to enhance the low intensity peaks (as shown in Figure 7), while N 2 and He just increased the signal of the overall spectra equally.…”