Optical Characterization of the Principal Hydrocarbon Components in Natural Gas Using Terahertz Spectroscopy

Abstract

A rapid technique is necessary to detect the natural gas which is a more and more significant fuel resource in modern industry. Terahertz (THz) technique was employed in this research to detect the principal hydrocarbon components of natural gas including methane, ethane, and propane. Two- and three-component mixtures were measured by THz setup, respectively. The amplitude ratio and time delay deviation of THz peaks between samples and reference were calculated. Phase projection pictures were obtained between the component concentrations and the amplitude ratio as well as time deviation. The phase figures evidently reflected the concentration dependent THz response, and a greatly different distribution was located in the whole phase projection area. In addition, back-propagation artificial neural networks method was utilized for the quantitative determination of components concentration and total pressure, and the correlation coefficient of the prediction set was proved to be 0.9859. Therefore, THz technique can satisfy the increasing need of rapid and efficient detection in the natural gas industry.

Industrial Applications of Terahertz Sensing: State of Play

“…TDS was used to demonstrate that THz measurements can establish the mixing ratios of natural gas [184,185]. As seen in Figure 25, the refractive index provides a good indicator of the mix, due to the differences in the indices of individual gases.…”

“…Refractive indices (mean over 0.3–1.3 THz) of natural gas constituents and their different mixes. Adapted from [184]. …”

Application of Terahertz Time-Domain Spectroscopy in Detecting Gaps with Different Widths

“…In addition, the terahertz technology has been applied to building materials, historical relics, reservoir rock, coal, oil and gas. [24][25][26][27][28][29][30][31][32] In the present work, the samples that were made by tableting were placed in parallel so as to imitate fractures with different scales. THz-TDS was used to detect gaps of samples, which will supplement existing methods.…”

Discriminating the Mineralogical Composition in Drill Cuttings Based on Absorption Spectra in the Terahertz Range

“…[19][20][21][22][23][24] Recently, the THz technique has also been applied in the petroleum and coal industries. [25][26][27][28][29] As a natural material, rocks with different compositions are expected to present different dielectric properties, which could be detected by THz waves. To date, THz spectroscopy has been applied for the investigation of the optical properties of marble, sandstone, and limestone.…”