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At least 1,441 records · Page 80

Steam gasification of waste tyre: Influence of process temperature on yield and product composition

Highlights: ► Steam gasification of waste tyre as matter and energy recovery treatment. ► Process temperature affects products yield and gas composition. ► High temperature promotes hydrogen production. ► Char exploitation as activated carbon or carbon source. - Abstract: An experimental survey of waste tyre gasification with steam as oxidizing agent has been conducted in a continuous bench scale reactor, with the aim of studying the influence of the process temperature on the yield and the composition of the products; the tests have been performed at three different temperatures, in the range of 850–1000 °C, holding all the other operational parameters (pressure, carrier gas flow, solid residence time). The experimental results show that the process seems promising in view of obtaining a good quality syngas, indicating that a higher temperature results in a higher syngas production (86 wt%) and a lower char yield, due to an enhancement of the solid–gas phase reactions with the temperature. Higher temperatures clearly result in higher hydrogen concentrations: the hydrogen content rapidly increases, attaining values higher than 65% v/v, while methane and ethylene gradually decrease over the range of the temperatures; carbon monoxide and dioxide instead, after an initial increase, show a nearly constant concentration at 1000 °C. Furthermore, in regards to the elemental composition of the synthesis gas, as the temperature increases, the carbon content continuously decreases, while the oxygen content increases; the hydrogen, being the main component of the gas fraction and having a small atomic weight, is responsible for the progressive reduction of the gas density at higher temperature.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Density Functional Theory Calculations of Mass Transport in UO2

In this talk we present results of density functional theory (DFT) calculations of U, O and fission gas diffusion in UO{sub 2}. These processes all impact nuclear fuel performance. For example, the formation and retention of fission gas bubbles induce fuel swelling, which leads to mechanical interaction with the clad thereby increasing the probability for clad breach. Alternatively, fission gas can be released from the fuel to the plenum, which increases the pressure on the clad walls and decreases the gap thermal conductivity. The evolution of fuel microstructure features is strongly coupled to diffusion of U vacancies. Since both U and fission gas transport rates vary strongly with the O stoichiometry, it is also important to understand O diffusion. In order to better understand bulk Xe behavior in UO{sub 2{+-}x} we first calculate the relevant activation energies using DFT techniques. By analyzing a combination of Xe solution thermodynamics, migration barriers and the interaction of dissolved Xe atoms with U, we demonstrate that Xe diffusion predominantly occurs via a vacancy-mediated mechanism. Since Xe transport is closely related to diffusion of U vacancies, we have also studied the activation energy for this process. In order to explain the low value of 2.4 eV found for U migration from independent damage experiments (not thermal equilibrium) the presence of vacancy clusters must be included in the analysis. Next we investigate species transport on the (111) UO{sub 2} surface, which is motivated by the formation of small voids partially filled with fission gas atoms (bubbles) in UO{sub 2} under irradiation. Surface diffusion could be the rate-limiting step for diffusion of such bubbles, which is an alternative mechanism for mass transport in these materials. As expected, the activation energy for surface diffusion is significantly lower than for bulk transport. These results are further discussed in terms of engineering-scale fission gas release models. Finally, oxidation of UO{sub 2} and the importance of cluster formation for understanding thermodynamic and kinetic properties of UO{sub 2+x} are investigated.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

Molecular dynamics study of silicon atomic layer etching by chlorine gas and argon ions

Classical molecular dynamics (MD) is used to simulate atomic layer etching processes of silicon by alternating exposure to chlorine gas and argon ions. In order to validate our model, a rigorous comparison is done with ion beam experiments found in the literature [Park et al., Jpn. J. Appl. Phys. 44, 389 (2005)]. Here it is shown that the etch per cycle (EPC) as a function of argon ion energy from simulations is in quantitative agreement with experimental results if the correct argon ion fluence is used in the simulations. The EPC as a function of ion irradiation time and amount of chlorine exposure also show good agreement with the experiment. The MD simulations also show the formation of an amorphous silicon region with chlorine atoms mixed uniformly throughout following ion bombardment. Finally, the etch products during the ion irradiation step are analyzed and discussed.

74 ATOMIC AND MOLECULAR PHYSICS↗

Characterization of Complex Interactions at the Gas–Solid Interface with in Situ Spectroscopy: The Case of Nitrogen-Functionalized Carbon

Interactions at the gas-solid interface drive physicochemical processes in many energy and environmental applications; yet, the challenges associated with characterization and development of these dynamic interactions in complex systems limit progress in developing effective materials. Thus, structure-property-performance correlations greatly depend on the development of advanced techniques and analysis methods for the investigation of gas-solid interactions. In this work, adsorption behavior of O 2 and humidified O 2 on nitrogen-functionalized carbon (N-C) materials was investigated to provide a better understanding of the role of nitrogen species in the oxygen reduction reaction (ORR). N-C materials were produced by solvothermal synthesis and N-ion implantation, resulting in a set of materials with varied nitrogen amount and speciation in carbon matrices with different morphologies. Adsorption behavior of the N-C samples was characterized by in situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and ambient pressure X-ray photoelectron spectroscopy (AP-XPS) experiments. A novel analysis approach for the interpretation of AP-XPS data was developed, allowing both the determination of overall adsorption behavior of each N-C material and identification of which nitrogen species were responsible for adsorption. The complementary information provided by in situ DRIFTS and AP-XPS suggests that O 2 adsorption primarily takes place on either electron-rich nitrogen species like pyridine, hydrogenated nitrogen species, or graphitic nitrogen. Adsorption of O 2 and H 2 O occurs competitively on solvothermally prepared N-Cs, whereas adsorption of H 2 O and O 2 occurs at different sites on N-ion implanted N-Cs, highlighting the importance of tuning the composition of N-C materials to promote the most efficient ORR pathway.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Portable chemical detection platform for on-site monitoring of odorant levels in natural gas

The adequate odorization of natural gas is critical to identify gas leaks and to reduce accidents. To ensure odorization, natural gas utility companies collect samples to be processed at core facilities or a trained human technician smells a diluted natural gas sample. In this work, we report a detection platform that addresses the lack of mobile solutions capable of providing quantitative analysis of mercaptans, a class of compounds used to odorize natural gas. Detailed description of the platform hardware and software components is provided. Designed to be portable, the platform hardware facilitates extraction of mercaptans from natural gas, separation of individual mercaptan species, and quantification of odorant concentration, with results reported at point-of-sampling. The software was developed to accommodate skilled users as well as minimally trained operators. Detection and quantification of six commonly used mercaptan compounds (ethyl mercaptan, dimethyl sulfide, n-propylmercaptan, isopropyl mercaptan, tert–butyl mercaptan, and tetrahydrothiophene) at typical odorizing concentrations of 0.1–5 ppm was performed using the device. We demonstrate the potential of this technology to ensure natural gas odorizing concentrations throughout distribution systems.

03 NATURAL GAS↗

Design and Modeling of Vacuum Pumping for Steady-State Pellet Fueling Systems

We report that future long-pulse magnetic confinement fusion reactors will require density and isotopic mixture control using steady-state repeating pellet injectors. For high-energy density burning plasmas, pellet velocities of 1 km/s and above will be required for sufficient plasma penetration to achieve high fueling efficiency. Currently, steady-state repeating injection systems utilize cryogenic extruder systems to produce an extrusion of solid deuterium or deuterium-tritium. In repeating light gas gun injectors, the solid extrusion is cut and simultaneously loaded into a barrel. Once loaded, a fast operating gas valve delivers a high pressure burst of gas to accelerate the pellet down the barrel and into the machine. This process takes ~10 ms to achieve. Adequate gas pumping of the extruder exhaust and injection line propellant gas collection chambers is necessary for optimal operation of the pellet fueling system. Excess solid from the extruder sublimates in an exhaust chamber. The gas pressure in the extruder exhaust chamber must remain low to maintain low heating loads on the cooling mechanism (cryorefrigerators or liquid helium flow) and to reduce thermal conduction to the extrusion. Pumping the injection line chambers is necessary to limit propellant gas flow into the machine. A numerical simulation code was created to predict temporal pumping performance for these repeating pellet injection systems. Lastly, this paper outlines the methods and assumptions used to create this model and compares results to the pellet injection system currently employed on DIII-D, the steady-state pellet injection system planned for the Wendelstein 7-X, and a brief analysis of the ITER conceptual pellet fueling system.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

The MASSIVE Survey. VI. The Spatial Distribution and Kinematics of Warm Ionized Gas in the Most Massive Local Early-type Galaxies

We present the first systematic investigation of the existence, spatial distribution, and kinematics of warm ionized gas as traced by the [O ii] 3727 Å emission line in 74 of the most massive galaxies in the local universe. All of our galaxies have deep integral-field spectroscopy from the volume- and magnitude-limited MASSIVE survey of early-type galaxies with stellar mass log(M{sub ∗}/M{sub ⊙})>11.5 (M {sub K} < −25.3 mag) and distance D < 108 Mpc. Of the 74 galaxies in our sample, we detect warm ionized gas in 28, which yields a global detection fraction of 38 ± 6% down to a typical [O ii] equivalent width limit of 2 Å. MASSIVE fast rotators are more likely to have gas than MASSIVE slow rotators with detection fractions of 80 ± 10% and 28 ± 6%, respectively. The spatial extents span a wide range of radii (0.6–18.2 kpc; 0.1–4R {sub e}), and the gas morphologies are diverse, with 17/28 ≈ 61 ± 9% being centrally concentrated, 8/28 ≈ 29 ± 9% exhibiting clear rotation out to several kiloparsecs, and 3/28 ≈ 11 ± 6% being extended but patchy. Three out of four fast rotators show kinematic alignment between the stars and gas, whereas the two slow rotators with robust kinematic measurements available exhibit kinematic misalignment. Our inferred warm ionized gas masses are roughly ∼10{sup 5} M {sub ⊙}. The emission line ratios and radial equivalent width profiles are generally consistent with excitation of the gas by the old underlying stellar population. We explore different gas origin scenarios for MASSIVE galaxies and find that a variety of physical processes are likely at play, including internal gas recycling, cooling out of the hot gaseous halo, and gas acquired via mergers.

79 ASTRONOMY AND ASTROPHYSICS↗

Handling and Properties of Methanol as a Marine Fuel

Given the increasing concern around greenhouse gas emissions and the decline in the availability of fossil fuels, there is increasing global demand to develop alternate fuels for maritime transportation that are sustainable and which have lower greenhouse gas emissions. Methanol is one such alternative fuel that has garnered considerable attention given its potential to be produced by more sustainable processes and its more favorable greenhouse gas emission profile in comparison with current fossil fuels. Understanding the physical and chemical properties of methanol under a range of conditions is essential for its development as a marine fuel. In this study, we seek to define physical and chemical properties of different methanol samples to simulate real-world storage conditions as these data are lacking in the literature. Several methanol samples were evaluated: nearly pure methanol; International Organization for Standardization (ISO) marine methanol (MM) grades A, B, and C; and methanol plus higher alcohols. We first evaluated all methanol samples for impurities, acetic acid content, density, and distillation range. We then characterized the effects of water absorption and found that methanol can easily absorb unacceptable water content from humid air within hours, necessitating storage conditions that prevent this process. In eight-week aging experiments at 20 °C and 40 °C in ambient air, we did not observe significant oxidation for any of the methanol samples; however, we did observe increases in acid number. We assessed the impact of contamination of methanol with water, marine gas oil (MGO), and an MGO–biodiesel mixture on density, viscosity, distillation range, and lubricity. Finally, we show that MGO contamination of methanol results in a slight increase in sooting tendency. In aggregate, our results provide an in-depth analysis of physical and chemical properties of methanol as well as the impacts of storage conditions and impurities on the properties of fuel methanol.

09 BIOMASS FUELS↗

3-Methyl-1,2-BN-Cyclopentane: A Promising H2 Storage Material?

We provide detailed characterization of properties for 3-methyl-1,2-BN-cyclopentane 1 that are relevant to H2 storage applications such as viscosity, thermal stability, H2 gas stream purity, and polarity. The viscosity of 1 at room temperature is 25±5 cP, about one fourth the viscosity of olive oil. TGA/MS analysis indicates that liquid carrier 1 is thermally stable at 30 °C but decomposes slowly at 50 °C. RGA data suggest that the H2 desorption from 1 is a clean process, producing relatively pure H2 gas. Compound 1 is a polar zwitterionic type liquid consistent with theoretical predictions and solvatochromic studies. "T.A. acknowledges support from the Fuel Cell Technology Program at U.S. DOE, Office of Energy Efficiency 65 and Renewable Energy. Pacific Northwest National Laboratory is operated by Battelle."

Luo, Wei↗

The formation of correlated states and optimization of the tunnel effect for low-energy particles under nonmonochromatic and pulsed action on a potential barrier

We consider peculiarities of the formation of a coherent correlated state (CCS) of a low-energy particle under frequency modulation of parameters of a harmonic oscillator that contains this particle by a broadband nonmonochromatic or asymmetric pulsed action. It is shown that in the case of modulation with frequency-normalized intensity, the maximum efficiency of CCS formation corresponds to a narrow-band action, while broadband modulation is optimal for the action with a constant spectral density. As in the case of monochromatic modulation, the maximum correlation coefficient, |r|{sub max}, under the nonmonochromatic action corresponds to parametric resonance at frequency Ω ≈ 2ω{sub 0}. Under a pulsed action, the maximum efficiency of CCS formation and, hence, the maximum probability of the tunnel effect, correspond to pulsed modulation with a short leading edge and a long trailing edge. In particular, under the action of a pulsed magnetic field with an amplitude of 10 kOe and the leading edge duration of 2 × 10{sup –7} s on a gas with deuterium ions, a CCS can be formed with the correlation coefficient |r|{sub max} ≈ 0.9998, for which the tunneling effect probability under the dd interaction at temperature T ≈ 300–500 K increases from D{sub r=0} ≈ 10{sup −80} to D{sub |r|{sub m{sub a{sub x=0.9998}}}}≈0.1. This process can occur in a gas with particle number density n < n{sub cr} ≈ 10{sup 17} cm{sup −3}. The method of CCS formation makes it possible to explain the results of an experiment in which substantial isotope changes were detected when a pulsed electric current and magnetic-field generation occurred.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Separated waste stream immobilization of iodine and off-gas caustic scrubber solution (Final Report)

In this work, the approach was to immobilize the CS solution in a glass-bonded composite of cancrinite/sodalite. The synthesis of ceramic waste forms was accomplished by low-temperature (~90°C) processes developed by the team in the framework of a previous NEUP project. By building on our earlier efforts for iodine waste forms, we minimized the schedule and technical risk while still providing novel process demonstrations for the off-gas waste forms. In the case of AgI-based sorbents, a proof-of-concept stripping process was shown to remove iodine from AgI by converting it to NaI(aq) followed by immobilization of these ions in iodosodalite (ISOD), which could be glass-bonded in the same way as for the CS solution cancrinite/sodalite powders.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

An alternative method of gas boriding applied to the formation of borocarburized layer

The borocarburized layers were produced by tandem diffusion processes: carburizing followed by boriding. An alternative method of gas boriding was proposed. Two-stage gas boronizing in N{sub 2}-H{sub 2}-BCl{sub 3} atmosphere was applied to the formation of iron borides on a carburized substrate. This process consisted in two stages, which were alternately repeated: saturation by boron and diffusion annealing. The microstructure and microhardness of produced layer were compared to those-obtained in case of continuous gas boriding in H{sub 2}-BCl{sub 3} atmosphere, earlier used. The first objective of two-stage boronizing, consisting in acceleration of boron diffusion, has been efficiently implemented. Despite the lower temperature and shorter duration of boronizing, about 1.5 times larger iron borides' zone has been formed on carburized steel. Second objective, the absolute elimination of brittle FeB phase, has failed. However, the amount of FeB phase has been considerably limited. Longer diffusion annealing should provide the boride layer with single-phase microstructure, without FeB phase. - Highlights: Black-Right-Pointing-Pointer Alternative method of gas boriding in H{sub 2}-N{sub 2}-BCl{sub 3} atmosphere was proposed. Black-Right-Pointing-Pointer The process consisted in two stages: saturation by boron and diffusion annealing. Black-Right-Pointing-Pointer These stages of short duration were alternately repeated. Black-Right-Pointing-Pointer The acceleration of boron diffusion was efficiently implemented. Black-Right-Pointing-Pointer The amount of FeB phase in the boride zone was limited.

36 MATERIALS SCIENCE↗

Open aperture flow cells for on-line optical analysis of process fluids

A flow cell system includes a vessel and a fluid located in the vessel. A fluid surface of the fluid can be vented to a first gas pressure. The fluid surface can have a first cross-sectional area. The flow cell system includes a conduit in fluid communication with the vessel and positioned downstream of the vessel. The conduit can have a region that includes one or more orifices and has a second cross-sectional area. The second cross-sectional area can be less than the first cross-sectional area. The one or more orifices can be vented to a second gas pressure. The second gas pressure can be equal to or greater than the first gas pressure. Methods for analyzing a process fluid can include characterizing the fluid in the conduit.

Launiere, Cari A.↗

Volatile organic compound sensing based on coral rock-like ZnO

Highlights: • A coral rock-like ZnO with porous structure was successfully synthesized. • Coral rock-like ZnO realized the large gas response towards VOCs. • The porous structure may play an essential role in the surface sensing reaction. - Abstract: This work presented highly sensitive coral rock-like ZnO to investigate the sensing performances for volatile organic compounds (VOCs), including formaldehyde, methylbenzene, methanol and acetone. The coral rock-like ZnO with porous structure was synthesized using a solvothermal process and subsequent calcination. The gas response of the sensor based on the coral rock-like ZnO was reported for the four types of VOC vapors at different operating temperatures and gas concentrations. It was found that the fabricated sensor was sensitive to the four gases, revealing large gas response as well as fast response and recovery speed, which was ascribed to its distinctive porous nanostructure, resulting in adequate surface sensing reaction and effective gas diffusion.

36 MATERIALS SCIENCE↗

Raman spectroscopy of oxygen carrier particles in harsh environments

Fossil fuel combustion processes generate CO2, a greenhouse gas of considerable concern. To reduce this emission, the National Energy Technology Laboratory (NETL) is evaluating alternative combustion approaches, including chemical looping combustion (CLC). This technique generates relatively pure CO2, suitable for subsequent capture and storage. CLC uses oxygen-carrier particles (OCPs) such as iron oxides, copper oxides, calcium sulfates, etc. to provide oxygen for the combustion process. Optimization of the overall combustion process requires knowledge of the oxidation state (e.g., content of Fe2O3 vs. Fe3O4) of the OCPs during the different stages of the CLC process. Unfortunately, the ability to make on-line measurements of the oxidation state of OCPs in harsh environments is lacking and new sensors need to be developed. We are evaluating non-contact, stand-off Raman spectroscopy to determine the relative concentrations of the oxidized and reduced forms of OCPs at temperatures between 800 °C and 1000 °C, and pressures of about 10 atm. Using cw and pulsed Raman spectroscopy, in combination with a pressurized high-temperature sample chamber, we have optimized the operating parameters such as laser wavelength, laser intensity, collection optic design, focal spot size, etc. and measured Raman spectra of various OCP materials at high temperatures. To extract from the Raman spectra relevant information such as the concentration ratio of a material in different oxidation states, the measured data needs to be processed, and statistical modeling and multivariate calibration need to be performed.

20 FOSSIL-FUELED POWER PLANTS↗

Small-scale pilot plant for gasification of coal and coal/biomass blends and conversion of derived syngas to liquid fuels via Fischer-Tropsch synthesis

This report describes the second phase of a project to design, construct and commission an integrated coal/biomass-to-liquids facility at a capacity of 1 bbl. /day at the University of Kentucky Center for Applied Energy Research (UK-CAER) – specifically for construction, commissioning and operating of the downstream process units for water-gas-shift, Fischer-Tropsch synthesis and balance of plant [BOP]. The deliverables from the operation of this pilot plant is firstly the liquid F-T products and finished fuels which are of interest to UK-CAER’s academic, government and industrial research partners. Going forward the facility will produce research quantities of F-T liquids and finished fuels for subsequent Fuel Quality Testing, Performance and Acceptability. Moreover, the facility is expected to be employed for a range of research and investigations related to: Feed Preparation, Characteristics and Quality; Coal and Biomass Gasification; Gas Clean-up/ Conditioning; Gas Conversion by -F-T Synthesis; Product Work-up and Refining; Systems Analysis and Integration; and Scale-up and Demonstration. Environmental Considerations - particularly how to manage and reduce carbon dioxide emissions from CBTL facilities and from use of the fuels will be a primary research objective. The results of this second phase study include the FEED study and detailed engineering design of the downstream processing units and BOP, the selection of a range of technologies and technology vendors, the as-built plant - its equipment and capabilities, and the results of two trial production runs, one with coal only and one with a coal/biomass blend. These are described in detail in this report.

01 COAL, LIGNITE, AND PEAT↗

BETO 2021 Peer Review - Biomethanation to Upgrade Biogas to Pipeline Grade Methane WBS 5.1.3.102

We are developing, innovating and de-risking a biomethanation process capable of megawatt-scale deployment that upgrades biogas waste streams to produce pipeline quality renewable natural gas (RNG). Biomethanation is a two-step process using a methanogenic microorganism to convert renewable hydrogen (H2) and waste carbon dioxide (CO2) to renewable methane (CH4) - the primary component in natural gas. Using biogenic CO2 from biogas sources like dairies, wastewater treatment plants, and landfills allows production of this drop-in direct replacement fuel to participate in the growing number of carbon markets; like California's Low Carbon Fuel Standard and the Federal Renewable Fuel Standard. The end-of-project goal is to demonstrate pipeline quality RNG production (> 95% CH4, < 4% H2, <1% CO2, < 0.2% O2 and < 4 parts per million hydrogen sulfide) using real biogas feedstocks. We will accomplish this goal by designing and building a pressurized (18 bar) mobile lab-scale (20L) bioreactor research platform, including integrated electrolyzer system, based on lessons learned from operating the 700L pilot system from Southern California Gas Company. In collaboration with Electrochaea, natural gas utilities and Argonne National lab, will provide the data to establish a preliminary range of carbon intensity to help accelerate the deployment of utility-scale H2 production and qualify the biomethanation pathway process for RNG production.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

Co-Processing Catalytic Fast Pyrolysis Oil in an FCC Reactor

Studies of co-processing catalytic fast pyrolysis (CFP) oil with vacuum gas oil (VGO) are conducted in a Davison Circulating Riser (DCR). The CFP oil (CFPO) for this study was produced by upgrading fast-pyrolysis vapors from pine in an ex-situ fixed-bed reactor. CFPOs were co-processed at up to 5 vol% with VGO at 521°C and 2.57 bar. The yields of oil, aqueous phase, tail gas, and coke were measured. The amount of coke was determined from the carbon containing components in the regenerator flue gas. A compositional analysis was conducted with gas chromatography and elemental analyzers. The organic liquids were distilled into gasoline, jet-fuel, diesel, and resid fractions. A biocarbon analysis was conducted on the organic phase and its individual boiling-point fractions. The results show a small decrease in liquid yield and a generally increased gas yield when co-processing CFPO with VGO. For experiments with E-Cat as catalyst, approximately 70% of biocarbon is incorporated into liquid fuels relative to fossil carbon, while more of the biocarbon is contained in tail gas (as carbon dioxide or olefins) and/or coke. The measurements indicate that cracked CFPO components are predominantly included in the jet-fuel and diesel fractions. A techno-economic analysis (TEA) estimated the minimum fuel selling price (MSFP) for fuel-range products derived from FCC co-processing of CFPO at $3 to $4 per gasoline-gallon equivalent (GGE) at a yield of 51 GGE per ton of biomass.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗