Gas Composition Measurements Research Articles

Development of the neutral gas diagnostic system for neutral pressure measurements and gas analysis on the SPARC tokamak.

A suite of plasma diagnostics will be installed on the SPARC tokamak to allow for real-time plasma control, an investigation of high-field tokamak physics, and to de-risk the design of ARC, a compact fusion power plant with the aim to supply electricity to the grid. Among these diagnostics is the neutral gas diagnostics system (NTGS), a set of pressure sensors and gas analyzers used to monitor neutral pressure and gas composition for plasma control, optimization of wall conditioning, and helium ash removal, among other measurement functions linked to operational and scientific research needs. While reliable measurements of neutral pressure and gas composition have been fielded on existing magnetic-confinement fusion devices, SPARC represents a step increase in challenge due to its larger power density, higher field, high vacuum vessel bake temperatures, and higher neutron flux environment, as well as a step decrease in the accessibility for maintenance of in-vessel sensors. Multiple sensor types will be employed to have defense-in-depth and mitigate common failure modes. The NTGS system is currently progressing through final design, working to close out decisions using prototyping and analysis, and then moving on to procuring sensors for assembly and installation on SPARC. This paper outlines the current status of the system design and the diagnostic requirements that motivate neutral gas measurements on SPARC, as well as highlights the planned prototyping activities.

The Influence of the Changes in Natural Gas Supplies to Poland on the Amount of Hydrogen Produced in the SMR Reactor

Thanks to investments in diversifying the supply of natural gas, Poland did not encounter any gas supply issues in 2022 when gas imports from Russia were ceased due to the Russian Federation’s armed intervention in Ukraine. Over the past few years, the supply of gas from routes other than the eastern route has substantially grown, particularly the supplies of liquefied natural gas (LNG) via the LNG terminal in Świnoujście. The growing proportion of LNG in Poland’s gas supply leads to a rise in ethane levels in natural gas, as verified by the review of data taken at a specific location within the gas system over the years 2015, 2020, and 2022. Using measurements of natural gas composition, the effectiveness of the steam hydrocarbon reforming process was simulated in the Gibbs reactor via Aspen HYSYS. The simulations confirmed that as the concentration of ethane in the natural gas increased, the amount of hydrogen produced, and the heat required for reactions in the reformer also increased. This article aims to analyze the influence of the changes in natural gas quality in the Polish transmission network caused by changes in supply structures on the mass and heat balance of the theoretical steam reforming reactor. Nowadays, the chemical composition of natural gas may be significantly different from that assumed years ago at the plant’s design stage. The consequence of such a situation may be difficulties in operating, especially when controlling the quantity of incoming natural gas to the reactor based on volumetric flow without considering changes in chemical composition.

High-Pressure Gravimetric Measurements for Binary Gas Adsorption Equilibria and Comparisons with Ideal Adsorbed Solution Theory (IAST).

Measurements of gas mixture adsorption equilibria at high pressures are important for assessing actual adsorbent selectivities but are often out of reach, given the challenging nature of the required experiments. Here, we report a high-pressure gravimetric binary gas adsorption equilibrium measurement system based on simultaneous gas density and mixture adsorption measurements in a single gas cell coupled to a magnetic-suspension balance. Compared to traditional techniques which rely on analytical measurements of gas composition, this approach does not require any sampling. Adsorption measurements of two gas mixtures (0.500 N2 + 0.500 CH4 and 0.400 N2 + 0.600 CO2, mole fraction) on a commercially available molecular sieve (NaY, sodium molecular sieve type Y) were carried out in the temperature range 282 to 325 K with a pressure up to 10 MPa. A prediction method for the gas mixture adsorption equilibria in a closed system using the ideal adsorbed solution theory (IAST) model was used to compare the experimental results. For binary mixtures of components with similar adsorption capacities (here N2 and CH4), the system can measure the adsorption equilibria at pressures higher than 1.0 MPa and the result agrees well with the IAST model prediction. For two gases with very different adsorption capacities, the uncertainty in the adsorption equilibrium measurement is much larger. The dominant uncertainty source is the gas density measurement, whose uncertainty could potentially be cut to half if the current titanium sinker is replaced with a sinker made of single-crystal silicon and with a larger volume.

Temporal Variability in Gas Emissions at Bagana Volcano Revealed by Aerial, Ground, and Satellite Observations

AbstractBagana is a remote, highly active volcano, located on Bougainville Island in southeastern Papua New Guinea. The volcano has exhibited sustained and prodigious sulfur dioxide gas emissions in recent decades, accompanied by frequent episodes of lava extrusion. The remote location of Bagana and its persistent activity have made it a valuable case study for satellite observations of active volcanism. This remoteness has also left many features of Bagana relatively unexplored. Here, we present the first measurements of volcanic gas composition, achieved by unoccupied aerial system (UAS) flights through the volcano's summit plume, and a payload comprising a miniaturized MultiGAS. We combine our measurements of the molar CO2/SO2 ratio in the plume with coincident remote sensing measurements (ground‐ and satellite‐based) of SO2 emission rate to compute the first estimate of CO2 flux at Bagana. We report low SO2 and CO2 fluxes at Bagana from our fieldwork in September 2019, ∼320 ± 76 td−1 and ∼320 ± 84 td−1, respectively, which we attribute to the volcano's low level of activity at the time of our visit. We use satellite observations to demonstrate that Bagana's activity and emissions behavior are highly variable and advance the argument that such variability is likely an inherent feature of many volcanoes worldwide and yet is inadequately captured by our extant volcanic gas inventories, which are often biased to sporadic measurements. We argue that there is great value in the use of UAS combined with MultiGAS‐type instruments for remote monitoring of gas emissions from other inaccessible volcanoes.

Investigation of hot spring gas components and soil gas fluxes in Arxan Holocene volcanic field, Inner Mongolia, NE China

The latest research results show that there is a unified magma system and heating channel beneath the Arxan volcanic field, indicating a potential risk of eruption. The Arxan volcanic field features multiple gas emission sites (e.g., Jinjianggou hot springs and Yinjianggou hot springs) and exhibits strong hydrothermal activity. In this study, measurements of the hot spring gas composition and soil CO2 flux in the Arxan Holocene volcanic field were conducted, and the results were combined with previous research results to analyze the degassing characteristics of this region. The results show that the volcanic gases in the Arxan volcanic field are composed of 0.07%–1.09% CO2, 0.33–12 ppm CH4, 1.57–53 ppm H2, 800–30,241 ppm He, and 1.14%–1.86% Ar. The He content in this area is notably higher than that in other dormant volcanoes in China. This difference is possibly caused by U–Th decay in the Mesozoic granodiorite and acidic volcanic rocks in the study area, which can produce substantial radiogenic He. The soil gas concentrations near the Jinjianggou and Yinjianggou hot springs are higher than those of two Holocene volcanoes. The peak CO2 concentration in the soil near the Jinjianggou hot spring can reach 35,161 ppm. The single-site soil microseepage CO2 flux in the Arxan volcanic field is 4.66–107.18 g m−2 d−1, and the estimated annual CO2 emission flux from the volcanic field to the atmosphere is 0.63 × 105 t, which also demonstrates that soil CO2 flux of Arxan volcano is comparable to the soil CO2 emission level of the Iwojima volcano.

Compositional Mixing Characteristics of Separate Gas and Oil Charges into Oil Field Reservoirs

Many reservoirs worldwide received separate charges of primary biogenic gas and oil. In high pressure provinces such as the Gulf of Mexico, the added gas should be in solution if thoroughly mixed. In addition, this biogenic gas is easily differentiated from thermogenic gas by measurement of methane carbon isotopes and gas composition. Consequently, the extent of mixing can be determined with accuracy, and the gas and oil mixing processes depend on specifics of reservoir charging and can lead to multiple outcomes. The conventional expectation is that the biogenic gas always precedes oil entry into the reservoir. Here, chemical evaluation of reservoir fluids coupled with reservoir understanding of several reservoirs establishes that the oil can arrive prior to biogenic gas. Seismic imaging of gas chimneys provides a plausible explanation for how this can occur. In addition, thermodynamic and geochemical evaluation of the reservoir fluids across the reservoir tightly constrains possible mixing processes. Simple reservoir simulation shows that excellent gas and oil mixing can occur over a wide range of conditions provided that the gas charges into the oil column at its bottom (at the oil–water contact). This modeling exhibits simple fluid mechanics expectations for this reservoir charging process. In addition, since the increase of solution gas destabilizes asphaltenes, fluid geodynamic processes are indicated that can lead to redistributions of asphaltenes. Evaluation of gas and oil mixing processes in reservoirs fits within the framework of the powerful new technical discipline, reservoir fluid geodynamics, for subsurface characterization.

Effect of Crosslink Density on Thermal Aging of Bio-Based Rigid Low-Density Closed-Cell Polyurethane Foams

Gradual replacement of the traditional raw materials in polyurethane (PU) synthesis by bio-based ones and introduction of environmentally friendly physical blowing agents (PBAs) motivate the analysis of thermal aging of bio-based foams in order to optimize the chemical structure of the PU matrix so that its permeability to PBA is minimized. With the aim of elucidating the effect of the PU chemical structure on thermal aging of foams, rigid low-density closed-cell PU foams were produced solely from bio-based polyols. The effective diffusivities of PBA and atmospheric gasses were evaluated based on the measured thermal conductivity aging of foams and validated by gas chromatography measurements of gas composition in foam cells. Gas permeability of the PU polymer was estimated based on effective diffusivity in foams and foam morphology and found to decrease with increasing crosslink density, apparently due to reduction in the fractional free volume in the polymers.

Gas composition measurements in randomly distributed and fast moving gas bubbles in two-phase fluids.

Gas composition in randomly distributed and fast-moving bubbles was optically measured aided by laser-induced breakdown spectroscopy (LIBS). Laser pulses were focused at a point in a stream of bubbles to induce plasmas for the LIBS measurements. The distance between the laser focal point and liquid-gas interface, or 'depth,' plays a major role in determining the plasma emission spectrum in two-phase fluids. However, the 'depth' effect has not been investigated in previous studies. Therefore, we evaluated the 'depth' effect in a calibration experiment near a still and flat liquid-gas interface using proper orthogonal decomposition, and a support vector regression model was trained to exclude the influence of the interfacing liquid and extract gas composition information from the spectra. The gaseous molecular oxygen mole fraction in the bubbles was accurately measured under realistic two-phase fluid conditions.

Catalytic reactor for operando spatially resolved structure-activity profiling using high-energy X-ray diffraction.

In heterogeneous catalysis, operando measurements probe catalysts in their active state and are essential for revealing complex catalyst structure-activity relationships. The development of appropriate operando sample environments for spatially resolved studies has come strongly into focus in recent years, particularly when coupled to the powerful and multimodal characterization tools available at synchrotron light sources. However, most catalysis studies at synchrotron facilities only measure structural information about the catalyst in a spatially resolved manner, whereas gas analysis is restricted to the reactor outlet. Here, a fully automated and integrated catalytic profile reactor setup is shown for the combined measurement of temperature, gas composition and high-energy X-ray diffraction (XRD) profiles, using the oxidative dehydrogenation ofC2H6 to C2H4 over MoO3/γ-Al2O3 as a test system. The profile reactor methodology was previously developed for X-ray absorption spectroscopy and is here extended for operando XRD. The profile reactor is a versatile and accessible research tool for combined spatially resolved structure-activity profiling, enabling the use of multiple synchrotron-based characterization methods to promote a knowledge-based optimization of a wide range of catalytic systems in a time- and resource-efficient way.

Influence of Yttria-Stabilized Zirconium Oxide Thermal Swing Coating on the Flame-Wall Interaction in Spark Ignition Engines

Future vehicle powertrain systems with internal combustion engines must achieve higher efficiencies and further reduced pollutant emissions. This will require the application of new advanced technologies. Against this background, this paper presents a holistic approach to reduce temporally the wall heat losses, and hydrocarbon and carbon monoxide emissions with thermal coatings on the combustion chamber walls. For this purpose, an yttria-stabilized zirconia (YSZ) coating is applied and evaluated by different methods. The thin layer in combination with the low thermal effusivity of the material allows the wall temperature to follow the gas temperature and perform a so-called thermal swing. The interaction between an uncoated and a YSZ-coated wall with the flame front as well as partially burned gas was investigated. First, in terms of the coating’s potential to reduce the flame quenching distance using an optical method in a constant volume combustion chamber. Second, regarding its influence on the near-wall gas composition, which was analyzed with in-situ diffuse reflectance infrared Fourier transform spectroscopy measurements and a fast gas sampling technique on a single-cylinder engine. From this, it could be derived that the quenching distance can be reduced by 10% at ambient conditions and by 5% at an elevated temperature of 200 °C by using the coating. These findings also support the results that have been obtained by the near-wall gas composition measurements, where a reduced total hydrocarbon emission was found with the applied coating.

Characterization and performance of an acoustic sensor for fission gas release characterization devoted to JHR environment measurements

For over a decade, the IES laboratory has been working in collaboration with the CEA on the development of acoustic instrumentation in the nuclear field. As part of this collaboration, the IES acoustics team is developing a miniaturized gas composition sensor for in situ measurements of gas composition in a fuel rod. The first experimental use of an acoustic sensor to measure gas composition dates back to 2010 with the REMORA 3 experiment, which estimated the release of fission gas in an experimental fuel rod. Unlike the sensor tested during REMORA 3, this new sensor should be able to operate at 300°C, a performance made possible by the use of a piezoelectric element based on bismuth titanate (NBT). The material is screen-printed onto an alumina substrate. The manufacturing process and initial characterization were presented in the previous version of ANIMMA 2021 [1]. In this article, we will focus on the performance of this type of sensor by characterizing different gas mixtures representative of the gases inside a fuel rod, in order to estimate relative deviations under laboratory conditions.

Experimental assessment of an indirect method to measure the post-combustion flue gas flow rate in waste-to-energy plant based on multi-point measurements

In waste-to-energy plants, the determination of the flue gas flow rate in the post-combustion section is of the utmost importance, e.g., for the verification of the compliance to the minimum residence time requirements (tres>2s) or for the control of flue gas treatment reactant injection, but the harsh conditions (high temperature and content of pollutants) do not allow for a direct measurement. The present work reports an experimental assessment of an indirect approach to estimate the flue gas flow rate in the post-combustion section of a rotary kiln plant with reduced uncertainty. This method consists on the direct measurement of the flow rate at a “colder” section of the plant (the boiler outlet) combined to the simultaneous measurements of flue gas composition measurements upstream and downstream of the boiler. From these measurements it is then possible to determine the mass of false air and to retrieve the actual flue gas flow-rate in the post-combustion chamber. A massive experimental campaign has been conducted at a full-scale medical waste incinerator, in which flue gas flow rate was estimated at different waste loads and ambient conditions. The results show that the percentage of false air can be significant and simply neglecting it can lead to substantial under-performance of the plant. Issues related to the practical implementation of the methods are illustrated in detail and the possibility to extend the methodology towards an online determination of post-combustion flue gas flow rate is discussed.

Modeling composition of properties of biogas produced from the Co-digestion of cow-dung and organic kitchen waste

Public concerns about climate change, air pollution, water quality and rising energy consumption have place pressure on producers and industry to reduce emissions and promote pollution-free sources of energy. One of the most generally available sources of renewable energy is biogas; hence, this study on kinetic modeling of the biogas composition was carried out at ambient condition for a period of 30 days to supplement energy requirements in farms and houses. The substrates, cow dung and organic kitchen waste were co-digested at different ratios for biogas production at laboratory scale. The digesters substrate had 3300g of feed each with varying ratios of 70:30 (Sample A), 50:50 (Sample B), 40:60 (Sample C), and 30:70 (Sample D) of cow dung to organic kitchen waste respectively. A biogas analyzer was used for the measurement of gas composition, biodigester operating parameter were measured using a multi-meter, while gas volume was obtained using calibrated floating drum. The model showed polynomial correlation as best fit using the R2 method.

Monitoring of produced biogas volume and composition from co-digestion of Cow-dung and organic-kitchen-waste

This is an experimental study on produced biogas volume and volume from co-digestion of cow dung and food waste. This study was carried out at ambient condition. A gas meter was used for the measurement of gas composition, biodigester operating parameter were measured using a multi meter while gas volume was obtained from the observation of the floating drum. Four floating drum digesters were used for the experiment. The digesters held 3300 g of feed each with varying ratios of 70:30 (Sample A), 50:50 (Sample B), 40:60 (Sample C), and 30:70 (Sample D) of cow dung to kitchen waste respectively. The dilution ratio was 1:3 of feed to water which had a retention time of 30 days. The gas composition (CH4, CO, CO2, H2S), substrate pH and temperature were monitored to observe the changes. The results gotten were graphed and tabulated. The gas gotten from the biogas burnt which shows that the biodigesters produced methane (CH4) of more than 40% of the gas composition at certain points during the retention time.

In situ Raman investigation on gas components and explosion risk of thermal runaway emission from lithium-ion battery

The gas emission of lithium-ion battery thermal runaway (LIB-TR) is of great significance for the early warning and safety assessment of TR. A Raman spectroscopy methodology for in-situ real-time measurement of LIB-TR gas composition and explosion risk was proposed in this paper. The TR gas released by commercial 18,650 LIBs during external heating abuse was used to study its compositions at different states of charge (SOC) and atmosphere. The lower explosive limit (LEL), upper explosive limit (UEL) and explosive limit range (ELR) were calculated based on the gas composition detection results of Raman spectrum. The results show that Raman spectroscopy can detect organic solvent vapor (OSV) immediately when the safety valve is opened. When the TR occurs, the proportion of CO, CO2, H2, CH4, C2H4, and C3H6 increases rapidly. SOC and atmosphere directly affect the explosion characteristics of TR gas. In air atmosphere, LEL, UEL and ELR increase with the increase of SOC, and the explosion risk of TR gas in nitrogen atmosphere is lower than that in air atmosphere. The results reveal that Raman spectroscopy presents a promising tool for the early detection of LIB-TR and the explosion risk assessment of TR gas.

Composition of Flue Gases during Oxy-Combustion of Energy Crops in a Circulating Fluidized Bed

In recent years, global warming and climate change associated with emissions of CO2 from fossil fuel-fired power systems are a big worry for authorities in many countries worldwide. The utilization of biomass as an alternative, carbon-neutral fuel can reduce emissions of CO2 and other greenhouse gases. Furthermore, the coupling of oxy-combustion of biomass with CO2 capture is an option for carbon-negative power generation technology. In this study, emissions of NOx, SO2, and CO from the air- and oxy-combustion of three energy crops (Miscanthus giganteus, Sida hermaphrodita, and Salix viminalis) are presented and compared with emissions from other biomass fuels and reference coal. Combustion tests in air and O2/CO2 mixtures were conducted in a 12-kW bench-scale CFB combustor at 850 °C. Measurements of flue gas compositions were taken using an FTIR spectrometer. In all tested atmospheres, emissions of SO2, N2O, and CO for biomass were lower than those for the reference coal. The oxidation of volatile nitrogen compounds was behind high emissions of NOx from biomass burned in air and O2/CO2 mixtures. The lowest concentrations of NO were found in the 21% O2/70% CO2 mixture. Combustion in mixtures containing more oxygen (30% and 40% O2) led to a decrease in emissions of N2O and CO and an increase in emissions of NO and SO2.

Solid oxide fuel cells (SOFCs) fed with biogas containing hydrogen chloride traces: Impact on direct internal reforming and electrochemical performance

This study is particularly aimed at investigating the influence of hydrogen chloride traces in biogas on direct internal reforming in solid oxide fuel cells (SOFCs). The experiments are performed with simulated biogas containing methane to carbon dioxide ratio of 3:2, the usual average proportion in biogas. To the best of our knowledge, there are no reported studies that investigated the effect of hydrogen chloride on direct internal reforming by clearly establishing the effect of reforming with outlet gas composition measurements. The experiments at SOFC operating temperature of 850 °C reveals no negative effect on reforming or cell performance, with 4, 8, and 12 ppm(v) of hydrogen chloride in biogas. At 800 °C, there is no visible performance degradation, but a negligible amount of methane (∼ 1%) is detected in the anode off gas. Both the reforming and electrochemical performance are marginally affected at 750 °C. Further, post-test analyses (FESEM-EDS, XRD) of the used SOFC reveals no damage to the cell at microstructure level or chlorine poisoning. All the experiments are performed in the context of utilizing the biogas generated from sewage treatment plants in an SOFC system. The reported level of chlorine traces in biogas generated from sewage sludge is < 10 ppm(v) and hence the limit set for experiments is at par with this value.

Using inverting CO critical value to predict coal spontaneous combustion severity in mine gobs with considering air leakages – A case study

The mined-out space in underground coal mines increases due to the mining face advances. The airflow continuously could enter the mine gob via the air leakage channels, which may cause the coal in gob spontaneously ignite and combust. The gob is not accessible for personal direct gas composition measurement due to rock collapses and blockages. Thus, it is difficult to monitor its spontaneous combustion condition timely, which leads to the blindness of developing spontaneous combustion prevention measures. Therefore, it is important to understand the status of spontaneous combustion of residual coal in the gob in time. To more accurately predict the coal spontaneous combustion in gobs, this paper proposes a new model to predict the burning state of coal in the gob by using the gas-CO generated by coal spontaneous combustion with considering the action of air leakages in the gob. Then the reflected CO critical value in the corner of the longwall face in return airflow side can be derived. An example application is also presented in this paper, which shows that the proposed method could better reflect the spontaneous combustion state of gob, and the derived critical value can be used as an early warning message to prevent the coal spontaneous ignition in the gob and reduce the probability of coal spontaneous combustion accidents.

Experimental Studies of the Effect of Air Filter Pressure Drop on the Composition and Emission Changes of a Compression Ignition Internal Combustion Engine

This paper presents an experimental evaluation of the effect of air filter pressure drop on the composition of exhaust gases and the operating parameters of a modern internal combustion Diesel engine. A literature analysis of the methods of reducing the emission of toxic components of exhaust gases from SI engines was conducted. It has been shown that the air filter pressure drop, increasing during the engine operation, causes a significant decrease in power output and an increase in fuel consumption, as well as smoke emission of Diesel engines with the classical injection system with a piston (sectional) in-line injection pump. It has also been shown, on the basis of a few literature studies, that the increase in the resistance of air filter flow causes a change in the composition of car combustion engines, with the effect of the air filter pressure drop on turbocharged engines being insignificant. A programme, and conditions of tests, on a dynamometer of a modern six-cylinder engine with displacement Vss = 15.8 dm3 and power rating 226 kW were prepared, regarding the influence of air filter pressure drop on the composition of exhaust gases and the parameters of its operation. For each technical state of the air filter, in the range of rotational speed n = 1000–2100 rpm, measurements of exhaust gas composition and emission were carried out, as well as measurements and calculations of engine-operating parameters, namely that of effective power. An increase in the pressure drop in the inlet system of a modern Diesel truck engine has no significant effect on the emissions of CO, CO2, HC and NOx to the atmosphere, nor does it cause significant changes in the degree of smoke opacity of exhaust gases in relation to its permissible value. An increase in air filter pressure drop from value Δpf = 0.580 kPa to Δpf = 2.024 kPa (by 1.66 kPa) causes a decrease in the maximum filling factor value from ηυ = 2.5 to ηυ = 2.39, that is by 4.5%, and a decrease in maximum power by 8.8%.

NO formation during co-combustion of coal with two thermally treated biomasses

The combustion behavior of biomass as a fuel varies dependent on source of the raw material, but also on the type of pre-treatment. In this work steam exploded and torrefied woody biomass were studied with respect to NOx formation in co-firing experiments. Most of the reported data is based on small scale experiments and simulations. In this work, however, have three different cases been investigated experimentally in a 1.5MWth combustor supported by reaction simulations. One case corresponds to firing 100% Utah bituminous coal and two cases where 15% of the coal (on a mass basis) has been replaced with either torrefied or steam exploded biomass. Two of the cases was also studied in a utility scale 1.3 GWth industrial boiler. In both units did the case with pure coal result in the highest amount of NO formed, which was expected due to the higher amount of fuel-bound nitrogen in the coal, as compared to the biomass fuels. The fuel analyses indicate that the nitrogen content is the same in the two investigated biofuels. However, the amount of NO formed differed. Gas composition measurements reveal that the partitioning of volatile nitrogen species (HCN and NH3) varies between the biomass co-firing cases. This was investigated further using detailed reaction simulations and is suggested as the main reason for the observed difference in NO formation.