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Bahr MS, Wolff M. PAS-based analysis of natural gas samples. Front Chem 2023; 11:1328882. [PMID: 38179240 PMCID: PMC10764539 DOI: 10.3389/fchem.2023.1328882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 12/07/2023] [Indexed: 01/06/2024] Open
Abstract
Photoacoustic spectroscopy (PAS) is well known for the detection of short-chain hydrocarbons, such as methane, ethane and propane, in the ppm (parts per million) or ppb (parts per billion) range. However, in the production process of natural gas and its combustion in gas-fired devices the composition, especially the concentrations of the main alkanes, plays a decisive role. Gas chromatography (GC) is considered the gold standard for natural gas analysis. We present a method to analyze natural gas samples by PAS. Furthermore, we describe a method to prepare storage gas samples, which are usually under atmospheric pressure, for PAS analysis. All measurements are validated by means of GC. The investigation allows conclusions to be drawn to what extent PAS is suitable for the investigation of natural gas samples.
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Affiliation(s)
- Marc-Simon Bahr
- Heinrich Blasius Institute of Physical Technologies, Hamburg University of Applied Sciences, Hamburg, Germany
- School of Computing, Engineering and Physical Sciences, University of the West of Scotland, Paisley, United Kingdom
| | - Marcus Wolff
- Heinrich Blasius Institute of Physical Technologies, Hamburg University of Applied Sciences, Hamburg, Germany
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2
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Lai HWH, Benedetti FM, Ahn JM, Robinson AM, Wang Y, Pinnau I, Smith ZP, Xia Y. Hydrocarbon ladder polymers with ultrahigh permselectivity for membrane gas separations. Science 2022; 375:1390-1392. [PMID: 35324307 DOI: 10.1126/science.abl7163] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Membranes have the potential to substantially reduce energy consumption of industrial chemical separations, but their implementation has been limited owing to a performance upper bound-the trade-off between permeability and selectivity. Although recent developments of highly permeable polymer membranes have advanced the upper bounds for various gas pairs, these polymers typically exhibit limited selectivity. We report a class of hydrocarbon ladder polymers that can achieve both high selectivity and high permeability in membrane separations for many industrially relevant gas mixtures. Additionally, their corresponding films exhibit desirable mechanical and thermal properties. Tuning of the ladder polymer backbone configuration was found to have a profound effect on separation performance and aging behavior.
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Affiliation(s)
- Holden W H Lai
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Francesco M Benedetti
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jun Myun Ahn
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Ashley M Robinson
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Yingge Wang
- Advanced Membranes and Porous Materials Center, Chemical Engineering Program, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Ingo Pinnau
- Advanced Membranes and Porous Materials Center, Chemical Engineering Program, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Zachary P Smith
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yan Xia
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
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Mikaliunaite L, Sudol PE, Cain CN, Synovec RE. Baseline correction method for dynamic pressure gradient modulated comprehensive two-dimensional gas chromatography with flame ionization detection. J Chromatogr A 2021; 1652:462358. [PMID: 34237483 DOI: 10.1016/j.chroma.2021.462358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 11/18/2022]
Abstract
A baseline correction method is developed for comprehensive two-dimensional (2D) chromatography (GC × GC) with flame-ionization detection (FID) using dynamic pressure gradient modulation (DPGM). The DPGM-GC × GC-FID utilized porous layer open tubular (PLOT) columns in both dimensions to focus on light hydrocarbon separations. Since DPGM is nominally a stop-flow modulation technique, a rhythmic baseline disturbance is observed in the FID signal that cycles with the modulation period (PM). This baseline disturbance needs to be corrected to optimize trace analysis. The baseline correction method has three steps: collection of a background "blank" chromatogram and multiplying it by an optimized normalization factor, subtraction of the normalization-optimized background chromatogram from a sample chromatogram, and application of Savitzky-Golay smoothing. An alkane standard solution, containing pentane, hexane and heptane was used for method development, producing linear calibration curves (r2 > 0.991) over a broad concentration range (7.8 ppm - 4000 ppm). Further, the limit-of-detection (LOD) and limit-of-quantification (LOQ) were determined for pentane (LOD = 2.5 ppm, LOQ = 8.2 ppm), hexane (LOD = 0.9 ppm, LOQ = 3.0 ppm), and heptane (LOD = 1.9 ppm, LOQ = 6.4 ppm). A natural gas sample separation illustrated method applicability, whereby the DPGM produced a signal enhancement (SE) of 30 for isopentane, where SE is defined as the height of the tallest 2D peak in the modulated chromatogram for the analyte divided by the height of the unmodulated 1D peak. The 30-fold SE resulted in about a 10-fold improvement in the signal-to-noise ratio (S/N) for isopentane. Additional versatility of the baseline correction method for more complicated samples was demonstrated for an unleaded gasoline sample, which enabled the detection (and visual appearance) of trace components.
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Affiliation(s)
- Lina Mikaliunaite
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195, USA
| | - Paige E Sudol
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195, USA
| | - Caitlin N Cain
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195, USA
| | - Robert E Synovec
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195, USA.
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Design and Application of Mixed Natural Gas Monitoring System Using Artificial Neural Networks. SENSORS 2021; 21:s21020351. [PMID: 33430179 PMCID: PMC7825614 DOI: 10.3390/s21020351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/03/2021] [Accepted: 01/04/2021] [Indexed: 11/17/2022]
Abstract
Natural gas component analysis is one of the significant technologies in the exploitation and utilization of natural gas. A stable and accurate online natural gas monitoring system is necessary for the gas extracting industry. We have developed an online monitoring system of natural gas with a novel hardware architecture. It improves the dependability and maintainability of the system. A specific instruction set is designed to facilitate the coordination of software and hardware. To reduce the sample noise, the exponentially weighted moving average (EWMA) method is used to preprocess the real-time raw data of the sensor array. A tailored neural network is designed for calibration. And the relationship between the performance and the structure of the gas neural network is demonstrated to find the optimal solution for accuracy and hardware scale. The design not only focuses on the optimization of individual components but also focuses on system-level improvement. The system has been running stably for several months in the gas fields. It meets the requirements of stability, ease of use, maintainability, and online monitoring in industrial applications.
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Tschedanoff V, Schildhauer TJ, Biollaz SMA, Wokaun A. Portable gas chromatograph calibration with gases of varying viscosities. Talanta 2020; 225:121077. [PMID: 33592688 DOI: 10.1016/j.talanta.2020.121077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 10/24/2022]
Abstract
The quantitative analysis of gas mixtures with gas chromatography is based on the calibration with certified standards and the determination of a response relationship for each species by regression analysis. The conventional assumption of a constant amount-of-substance injected onto the column, the sample size, for all standards analyzed represents one of the largest sources of uncertainies in this analysis technique. For systems using time-based microinjectors, the sample size injected onto the column is determined by the opening time of a pneumatically actuated microvalve and therefore depends upon the gas velocity developed in the injector's microchannel. For this reason the sample size is not necessarily constant for a given opening time, but strongly correlates - according to fluid mechanic theory - with the gas mixture's dynamic viscosity. Neglecting these sample size variations leads to errors in the analysis up to 30%, depending on the diversity of the standards' viscosities, especially in processes with strongly changing hydrogen contents. A mathematical correction exploiting the inverse proportionality of the sample size and the sample's dynamic viscosity normalizes the injection amounts and minimizes the influence of the sample variations on the calibration regression. The data analysis based on the corrected normalized calibration is no longer viscosity dependent and can be applied to gas mixtures of any composition.
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Affiliation(s)
- Vera Tschedanoff
- General Energy Research Department, Paul Scherrer Institut, Villigen PSI, CH-5232, Switzerland
| | - Tilman J Schildhauer
- General Energy Research Department, Paul Scherrer Institut, Villigen PSI, CH-5232, Switzerland.
| | - Serge M A Biollaz
- General Energy Research Department, Paul Scherrer Institut, Villigen PSI, CH-5232, Switzerland
| | - Alexander Wokaun
- General Energy Research Department, Paul Scherrer Institut, Villigen PSI, CH-5232, Switzerland
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Jia T, Guo T, Wang X, Zhao D, Wang C, Zhang Z, Lei S, Liu W, Liu H, Li X. Mixed Natural Gas Online Recognition Device Based on a Neural Network Algorithm Implemented by a FPGA. SENSORS 2019; 19:s19092090. [PMID: 31060347 PMCID: PMC6540013 DOI: 10.3390/s19092090] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 04/27/2019] [Accepted: 05/02/2019] [Indexed: 11/26/2022]
Abstract
It is a daunting challenge to measure the concentration of each component in natural gas, because different components in mixed gas have cross-sensitivity for a single sensor. We have developed a mixed gas identification device based on a neural network algorithm, which can be used for the online detection of natural gas. The neural network technology is used to eliminate the cross-sensitivity of mixed gases to each sensor, in order to accurately recognize the concentrations of methane, ethane and propane, respectively. The neural network algorithm is implemented by a Field-Programmable Gate Array (FPGA) in the device, which has the advantages of small size and fast response. FPGAs take advantage of parallel computing and greatly speed up the computational process of neural networks. Within the range of 0–100% of methane, the test error for methane and heavy alkanes such as ethane and propane is less than 0.5%, and the response speed is several seconds.
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Affiliation(s)
- Tanghao Jia
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Tianle Guo
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xuming Wang
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Dan Zhao
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Chang Wang
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Zhicheng Zhang
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Shaochong Lei
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Weihua Liu
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Hongzhong Liu
- State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
| | - Xin Li
- Department of Microelectronics, School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China.
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Abstract
A novel approach to analysis of complex gaseous mixtures is presented. The approach is based on the utilization of a compact gas chromatograph in combination with an array of highly integrated and selective metal oxide (MOX) sensors. Thanks to the implementation of a multisensory detector, the device collects multiple chromatograms in a single run. The sensors in the integrated MEMS platform are very distinct in their catalytic properties. Hence, the time separation by chromatographic column is complemented by catalytic separation by a multisensory detector. Furthermore, the device can perform the analysis in a broad range of concentrations, from ppb to hundreds of ppm. Low ppb and even sub-ppb levels of detection for some analytes were achieved. As a part of this effort, nanocomposite gas sensors were synthesized for selective detection of hydrogen sulfide, mercaptans, alcohols, ketones, and heavy hydrocarbons.
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Permanent gas analysis using gas chromatography with vacuum ultraviolet detection. J Chromatogr A 2015; 1388:244-50. [DOI: 10.1016/j.chroma.2015.02.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/02/2015] [Accepted: 02/03/2015] [Indexed: 11/18/2022]
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Vopička O, De Angelis MG, Sarti GC. Mixed gas sorption in glassy polymeric membranes: I. CO2/CH4 and n-C4/CH4 mixtures sorption in poly(1-trimethylsilyl-1-propyne) (PTMSP). J Memb Sci 2014. [DOI: 10.1016/j.memsci.2013.06.065] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Yang FK, Zhang ZT, Chen F. The Method for Analysis of Hydrocarbon Mixtures C 1-C 5by Capillary Column Gas Chromatography. J CHIN CHEM SOC-TAIP 2008. [DOI: 10.1002/jccs.200800101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Vargha G, Milton M, Cox M, Kamvissis S. Harmonisation of coupled calibration curves to reduce correlated effects in the analysis of natural gas by gas chromatography. J Chromatogr A 2005; 1062:239-45. [PMID: 15679161 DOI: 10.1016/j.chroma.2004.11.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Quantitative analysis of natural gas depends on the calibration of a gas chromatograph with certified gas mixtures and the determination of a response relationship for each species by regression analysis. The uncertainty in this calibration is dominated by variations in the amount of the sample used for each analysis that are strongly correlated for all species measured in the same run. The "harmonisation" method described here minimises the influence of these correlations on the calculated calibration curves and leads to a reduction in the root-mean-square residual deviations from the fitted curve of a factor between 2 and 5. Consequently, it removes the requirement for each run in the calibration procedure to be carried out under the same external conditions, and opens the possibility that new data, measured under different environmental or instrumental conditions, can be appended to an existing calibration database.
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Affiliation(s)
- Gergely Vargha
- National Physical Laboratory, Queens Road, Teddington, Middlesex, UK
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