Chemical Composition Of Gas Research Articles

Theoretical analysis of the thermal conversion of RDF fuel in the context of Waste Management

The European Union strives to introduce waste-free or low-waste closed-loop technologies using material and energy recovery to manage natural resources in a rational manner. Therefore, European regulations require member states to progressively restrict the amount of landfill waste. The article presents the current shape of waste management in Poland, and also introduces the dominant form of RDF management in the cement industry. Nevertheless, the capacity of cement plants is limited, and the energy use of fuels from waste encounters difficulties related to a significant reduction in pollutant emissions, which is why the use of modern installations for the thermal conversion of waste such as pyrolysis and gasification is increasingly considered. Taking into account the promising energy properties of secondary fuels obtained during the pyrolysis process, the chemical composition of gas from RDF pyrolysis was modeled for a pilot installation operating in Poland. Determination of the combustible components allowed the calorific value of pyrolysis gas to be estimated, ranging from 28.2 - 28.7 MJ/m3. The obtained calorific encourages wider use of the waste pyrolysis process in order to obtain secondary fuels with promising energy parameters. It will contribute to a further reduction in the amount of deposited waste, and thus to creating environmentally-friendly closed-loop waste management.

Gas Disease Special in Chinese Medical Journal and Lester Institute of Medical Research

In the September of 1937, there was a special issue named Military Gas Disease Prevention and Simple Therapy published in Chinese Medical Journal. The special issue included chemical composition of gas, gas classification, vesiculation gas, other poisons, treatment of victims, emergency services, etc. The special issue was published at the time when Japan began its full-scale invasion of China, and during that time, Japan sent some of its chemical forces to Shanghai to cooperate with the Japanese army in using chemical weapons during the Battle of Shanghai. The author of this special issue was the Department of Pathology of the Lester Institute of Medical Research. Under the auspices of the heritage of the British Christian and architectural engineer Lester-Lester Trust, the Lester Institute of Medical Research was established in 1932. The gas disease special and related rescue work done by Lester Institute of Medical Research made an important contribution to the medicine, military medicine and national defense medicine of China during the wartime and even when and after the People's Republic of China was found.

Occurrence Forms, Composition, Distribution, Origin and Potential Hazard of Natural Hydrogen–Hydrocarbon Gases in Ore Deposits of the Khibiny and Lovozero Massifs: A Review

The Khibiny and Lovozero massifs—the world’s largest alkaline massifs—contain deposits with unique reserves of phosphorus and rare metals, respectively. The reduced gas content in the rocks and, especially, the ore deposits of these massifs is unusually high for igneous complexes, thus representing both geochemical and practical interests. There are three morphological types (or occurrence forms) of the gas phase in these deposits: occluded (predominantly in vacuoles of micro-inclusions in minerals), diffusely dispersed, and free. All three morphological types have the same qualitative chemical gas composition. Methane is the main component, and molecular hydrogen (which sometimes dominates) and ethane are the subordinate constituents. Heavier methane homologs (up to and including pentanes), alkenes, helium, and rarely carbon oxide and dioxide are present in minor or trace amounts. All three morphological types of gases are irregularly distributed in space to various degrees. Free gases also show a release intensity that varies in time. The majority of researchers recognize that the origin of these gases is abiogenic and mostly related to the formation of the massifs and deposits. However, the relative time and mechanism of their generation are still debated. Emissions of combustible and explosive hydrogen–hydrocarbon gases pose hazards during the underground mining of ore deposits. Therefore, the distinctive features of gas-bearing capacity are an essential part of the mining and geological characterization of such deposits because they provide a basis for establishing and implementing special measures of the gas regime during mining operations.

Hydrogen molecular ions and the violent birth of the Solar System.

Many pieces of evidence indicate that the Solar System youth was marked by violent processes: among others, high fluxes of energetic particles (greater than or equal to 10 MeV) are unambiguously recorded in meteoritic material, where an overabundance of the short-lived 10Be products is measured. Several hypotheses have been proposed to explain from where these energetic particles originate, but there is no consensus yet, mostly because of the scarcity of complementary observational constraints. In general, the reconstruction of the past history of the Solar System is best obtained by simultaneously considering what we know of it and of similar systems nowadays in formation. However, when it comes to studying the presence of energetic particles in young forming stars, we encounter the classical problem of the impossibility of directly detecting them toward the emitting source (analogously to what happens to galactic cosmic rays). Yet, exploiting the fact that energetic particles, such as cosmic rays, create [Formula: see text] and that an enhanced abundance of [Formula: see text] causes dramatic changes on the overall gas chemical composition, we can indirectly estimate the flux of energetic particles. This contribution provides an overview of the search for solar-like protostars permeated by energetic particles and the discovery of a protocluster, OMC-2 FIR4, where the phenomenon is presently occurring. This article is part of a discussion meeting issue 'Advances in hydrogen molecular ions: H3+, H5+ and beyond'.

Assessing effects of sulfate minerals on petroleum generation in sedimentary basins using hydrous pyrolysis: I. Light alkanes

Abstract A series of hydrous pyrolysis experiments were conducted to assess the role of sulfate minerals on the chemical and isotopic compositions of light hydrocarbons generated during thermal degradation of kerogen. The shale source rock with low maturity (Tmax = 425 °C) from Eagle Ford formation in southeast Texas was used in the experiments at 330 °C for the duration of 72 h, while the abundance of gypsum in each experiment varies from 0, 0.5, to 1 wt%. Under experimental conditions, the positive effect of gypsum on the yields of gaseous alkanes (C1 - C4) and CO2 has been explicitly observed, with an exponential relationship between the yield of each gas and the amount of gypsum. While the relative abundance of C2 - C4 alkanes has shown an increasing trend with gypsum, the gas dryness (C1/∑C1-4), however, decreased from 73.1% with no gypsum to 49.6% with gypsum of 1 wt%. It was attributed to lower overall yields and corresponding higher increased generation rates of C2 - C4 alkanes than methane through thermal cracking of kerogen and other organic compounds. The carbon isotope value of each alkane reached the highest in the experiment with 1 wt% gypsum. Compared to the experiment without gypsum, there was an increase of 11.5‰ for the δ13C value of methane with 1 wt% gypsum. The extent of this 13C enrichment between experiments with different amount of gypsum became less for C2 to C4. The δ13C value of CO2 was the highest among generated gases, ranging from −4.7 to −2.1‰. Combined with chemical compositions of gases, it suggested that enhanced thermal cracking reactions were predominant in generation of light alkanes with the presence of gypsum, whereas dissolution of carbonates was the main source of CO2. The reactions involving thermochemical sulfate reduction (TSR) were minor (if present) under experimental conditions, most likely due to the small quantity of gypsum (up to 1 wt%) and neutralization of acidity by carbonates. Nonetheless, the changes in chemical and isotopic compositions of light alkanes, which were ultimately caused by the presence of gypsum, need to be incorporated into geochemical proxies for assessing source rocks (maturation in particular) and their generation potential.

Chemical significance of different temperature regimes for cosmic-ray-induced heating of whole interstellar grains

Cosmic-ray-induced whole-grain heating induces evaporation and other processes that affect the chemistry of interstellar clouds. With recent data on grain heating frequencies as an input for a modified rate-equation astrochemical model, this study examines, which whole-grain heating temperature regime is the most efficient at altering the chemical composition of gas and ices. Such a question arises because low-temperature heating, albeit less effective at inducing evaporation of adsorbed species, happens much more often than high-temperature grain heating. The model considers a delayed gravitational collapse of a Bonnor-Ebert sphere, followed by a quiescent cloud core stage. It was found that the whole-grain heating regimes can be divided in three classes, depending on their induced physico-chemical effects. Heating to low-temperature thresholds of 27 and 30 K induce desorption of the most volatile of species - N2 and O2 ices, and adsorbed atoms. The medium-temperature thresholds 40, 50, and 60 K allow effective evaporation of CO and CH4, delaying their accumulation in ices. We find that the 40 K threshold is the most effective cosmic-ray induced whole-grain heating regime because its induced evaporation of CO promotes major abundance changes also for other compounds. An important role in grain cooling may be played by molecular nitrogen as the most volatile of the abundant species in the icy mantles. Whole-grain heating determines the sequence of accretion for different molecules on to grain surface, which plays a key role in the synthesis of complex organic molecules.

Experimental investigations of the two-stage pyrolytic processing of pulp and paper industry wood waste

The article presents results of experimental investigations of the two-stage pyrolytic processing of pulp and paper industry wood waste into gas, which combines pyrolysis of raw material and subsequent high-temperature heterogeneous cracking of volatile pyrolysis products in a fixed bed of the coke residue of raw material. Dependence of specific gas yield, chemical composition, heating value and specific tar content on the cracking temperature are obtained. In different conversion modes the following gas characteristics were obtained: specific yield up to 1.5 m3/kg, volumetric fraction of combustible components more than 92%, lower heating value 10.8–12.5 MJ/m3, specific tar content 10–100 mg/m3. The data obtained form the basis for calculating the energy and mass balance of pilot unit of the two-stage pyrolytic conversion of pulp and paper industry wood waste into gas.

Influence of high ethane content on natural gas ignition

The effect of ethane on combustion and natural gas autoignition was studied in the present paper. Two fuel mixture of natural gas with high ethane content were considered, 75% CH4 – 25% C2H6 (mixture 1), and 50% CH4 – 50% C2H6 (mixture 2). Natural gas combustion incidence was analyzed through the calculation of energy properties and the ignition delay time numerical calculations along with an ignition mode analysis. Specifically, the strong ignition limit was calculated to determine the effect of ethane on natural gas autoignition. According to the results, ignition delay time decreases for both mixtures in comparison with pure methane. The strong ignition limit shifts to lower temperatures when ethane is present in natural gas chemical composition.

Gas generation potential and processes of Athabasca oil sand bitumen from gold tube pyrolysis experiments

Gold-tube pyrolysis experiments were conducted on two oil sand bitumens (OSBs) from the top and bottom of the McMurray Formation in the Athabasca oil sand region of Alberta, Canada. Temperatures ranging from 300 °C to 650 °C and a pressure of 50 MPa with heating rates of 2 °C/h were used to investigate the gas generation behavior of OSB. The extractable residual bitumen content decreased systematically with increasing heating temperatures resulting in a continuous increase in total hydrocarbon gas yields with the highest value of about 480 mg/g bitumen at 650 °C. Among hydrocarbon gases, the yields of methane (C1) increased consistently with experimental temperatures, while the yields of ethane (C2), propane (C3), butanes (i + n-C4) and pentanes (i + n-C5) increased initially to a critical pyrolysis temperature and then decreased at higher temperatures. Molecular indices (C1/C2, C2/C3, C2/i-C4, C3/C4, i-C4/n-C4, i-C5/n-C5 and C1/ΣC1-5) obtained in this work are different from typical primary thermogenic gases generated from kerogen or secondary thermogenic gases derived from thermal cracking of oil. Three stages of OSB thermal evolution were identified over a wide range of heating temperatures. The first stage (300–425 °C) reflects initial decomposition of thermally unstable moieties in resins and asphaltenes. Gas generated at this stage was dominated by carbon dioxide and hydrogen sulfide with minor amounts of hydrocarbon. Hydrocarbon gases were enriched in wet gas components with increasing heating temperatures. The second stage (425–525 °C) corresponds to liquid oil cracking and wet gas generation. While the yields of methane and ethane still increased with heating temperatures, yield of propane reached a maximum and yields of butane and pentane started to decline. The third stage (525–650 °C) reflects wet gas cracking and dry gas generation as indicated by the dramatic decrease of wet gas components and increase in gas dryness. Variations of gas yields and chemical compositions from two OSBs were partially caused by different levels of biodegradation. The top OSB has experienced less biodegradation influence than the bottom one as indicated by higher saturated and aromatic hydrocarbon contents and intact alkylphenanthrene distribution. Increased biodegradation of OSB yielded a higher concentration of polar compounds and an overall lower hydrogen content, which reduced the hydrocarbon gas generation potential. Slightly higher amounts of wet gas components were generated from the top OSB because of the relatively higher content of reactive moieties (mainly alkyl groups) at a lower biodegradation level, while a higher proportion of methane was observed from the bottom, severely biodegraded OSB that was enriched in cross linked ring structures.

Method and Device of Pyrolytic Processing of Pulp and Paper Industry’ Waste into High-Quality Synthesis Gas

Paper presents the results of the experimental investigations of the pulp and paper industry’ wood waste processing method into high-quality synthesis gas. The main characteristics of feedstock (moisture and ash content, elemental composition, higher and lower heating values, volatile matter and fixed carbon content) and synthesis gas (yield, chemical composition, heating value and tar content) in dependence of the processing parameters are described. Processing is carried out by the two-stage pyrolytic conversion method, combining pyrolysis and subsequent high-temperature cracking of volatiles in the charcoal fixed bed. The principal scheme and results of the thermotechnical characteristics calculation of the pilot plant capacity of 300 kg/h of raw material (mechanical mixture of wood chips and bark with a moisture content of 48 %) are presented. The obtained results confirm the high efficiency of the method as applied to the processing of this type of waste.

Equilibrium chemistry down to 100 K

We have introduced a fast and versatile computer code, GGCHEM, to determine the chemical composition of gases in thermo-chemical equilibrium down to 100 K, with or without equilibrium condensation. We have reviewed the data for molecular equilibrium constants, kp(T), from several sources and discussed which functional fits are most suitable for low temperatures. We benchmarked our results against another chemical equilibrium code. We collected Gibbs free energies, ΔGf⊖, for about 200 solid and liquid species from the NIST-JANAF database and the geophysical database SUPCRTBL. We discussed the condensation sequence of the elements with solar abundances in phase equilibrium down to 100 K. Once the major magnesium silicates Mg2SiO4[s] and MgSiO3[s] have formed, the dust to gas mass ratio jumps to a value of about 0.0045 which is significantly lower than the often assumed value of 0.01. Silicate condensation is found to increase the carbon to oxygen ratio (C/O) in the gas from its solar value of ~0.55 up to ~0.71, and, by the additional intake of water and hydroxyl into the solid matrix, the formation of phyllosilicates at temperatures below ~400 K increases the gaseous C/O further to about 0.83. Metallic tungsten (W) is the first condensate found to become thermodynamically stable around 1600–2200 K (depending on pressure), several hundreds of Kelvin before subsequent materials such as zirconium dioxide (ZrO2) or corundum (Al2O3) can condense. We briefly discuss whether tungsten, despite its low abundance of ~2 × 10−7 times the silicon abundance, could provide the first seed particles for astrophysical dust formation.

Analysis of Biomass Blend Co-Firing for Post Combustion CO2 Capture

The correct conduction of the CO2 capture process in coal-fired power plants with the use of monoethanolamine (MEA) requires constant process parameter monitoring and ensuring a specific flue gas chemical composition. One of the most common problems in these types of installations is the progressive corrosion and degradation of the valuable solvent. Despite the established reduction levels of oxygen and impurities entering into irreversible reactions with the absorber, the flue gas composition may change as a daily and annual function of time. The article presents a detailed analysis of the flue gas components that have the greatest influence on carbon dioxide capture installation technical safety, i.e., SOx, NOx, O2, and fly ash. The analysis was based on the results of experiments conducted at the Jaworzno III Tauron Wytwarzanie SA Polish coal power plant. The results show a significant influence of the flue gas desulfurization (FGD) process on MEA oxidative degradation. The amount of oxygen in flue gas during biomass and coal blend co-firing was nearly twice as low compared to pure coal combustion. Differences were also observed in the amounts of gas impurities with relation to the time of year and time of day of power plant operation.

Reduced gas seepages in ophiolitic complexes: Evidences for multiple origins of the H2-CH4-N2 gas mixtures

This paper proposes a comparative study of reduced gas seepages occurring in ultrabasic to basic rocks outcropping in ophiolitic complexes based on the study of seepages from Oman, the Philippines, Turkey and New Caledonia. This study is based on analyses of the gas chemical composition, noble gases contents, stable isotopes of carbon, hydrogen and nitrogen. These seepages are mostly made of mixtures of three main components which are H2, CH4 and N2 in various proportions. The relative contents of the three main gas components show 4 distinct types of gas mixtures (H2-rich, N2-rich, N2-H2-CH4 and H2-CH4). These types are interpreted as reflecting different zones of gas generation within or below the ophiolitic complexes. In the H2-rich type, associated noble gases display signatures close to the value of air. In addition to the atmospheric component, mantle and crustal contributions are present in the N2-rich, N2-H2-CH4 and H2-CH4 types. H2-bearing gases are either associated with ultra-basic (pH 10–12) spring waters or they seep directly in fracture systems from the ophiolitic rocks. In ophiolitic contexts, ultrabasic rocks provide an adequate environment with available Fe2+ and alkaline conditions that favor H2 production. CH4 is produced either directly by reaction of dissolved CO2 with basic-ultrabasic rocks during the serpentinization process or in a second step by H2-CO2 interaction. H2 is present in the gas when no more carbon is available in the system to generate CH4. The N2-rich type is notably associated with relatively high contents of crustal 4He and in this gas type N2 is interpreted as issued mainly from sediments located below the ophiolitic units.

Increases in CO2 from past low to future high levels result in “slower” strategies on the leaf economic spectrum

Depending on resource availability plants exhibit a specific suite of traits. At the interspecific level these traits follow the leaf economic spectrum (LES), traits related to slow turnover when resources are poor and fast turnover when resources are plentiful. Limited data shows that within species, CO2 availability, low in the recent geologic past, high in the near future, has led to plants shifting their trait levels on the LES towards faster traits. We asked whether adjustments of physiological traits could underpin faster growth from low to high CO2 and how these responses varied among plant functional types. We analysed the trait response of seedlings of up to 28 C3 plant species grown at low (160ppm), near-ambient (450ppm), and high (750ppm) CO2. We measured growth, specific leaf area (SLA), leaf gas exchange, chemical composition and stomatal traits. On average photosynthesis was reduced by 59% at low CO2 and increased by 14% at high CO2 compared to ambient CO2. Respiration decreased by 21% at low CO2 and increased by 39% at high CO2. Nitrogen content (N) per mass increased by 50% at low CO2 and decreased by 9% at high CO2. Plants drastically increased SLA at low CO2 so that despite lower carbon gain per area, carbon gain per unit mass was not reduced as much. Contrary to the responses to other resources, plant traits along the LES are adjusted towards the “fast” end of the spectrum (higher SLA, higher N) at low CO2 and towards the “slow” end (lower SLA, lower N) with increasing CO2. For a limited number of species photosynthesis per unit mass showed the same, increase at low CO2. From a resource economics perspective plants thus adjust the cost for growth towards the availability of carbon and the rate of assimilation: at lower CO2 the carbon costs decrease due to decreased respiration and lower leaf mass per area (higher SLA thinner leaves). At higher CO2 the carbon costs increase due to increased respiration and higher leaf mass per area (lower SLA thicker leaves). This suggests that CO2 increases from the past to the future are allowing plant species globally to combine faster growth with more robust, resource conservative leaves.

Curing and thermal degradation of diglycidyl ether of bisphenol A epoxy resin crosslinked with natural hydroxy acids as environmentally friendly hardeners

The paper presents the curing of diglycidyl ether of bisphenol A (DGEBA) with two natural hydroxy acids and the thermal behavior of the cured products. The kinetics of the curing reactions were evaluated from the differential scanning calorimetry (DSC) curves using Ozawa, Kissinger methods and “Thermokinetics-3” software (Netzsch). Thermal decomposition behavior of the cured products up to 600°C (in nitrogen) was made using simultaneous TG/FT-IR/MS technique. The kinetic parameters were obtained using the same software which shows that the thermal degradation takes place in three or four consecutive steps. The chemical composition of gases evolved at the thermal decomposition has been identified using FT-IR and MS techniques. The main products are: water, carbon dioxide, acids, anhydrides, aliphatic and aromatic hydrocarbons.

Innovative filters made of polyoxadiazole fibers for industrial gas and dust emissions treatment

Practicability of modern high thermal resistant polyoxadiazole fibers in the production of filtration textile materials for gas treatment stations is shown. Thermogravimetric researches proved high thermal resistance (up to 400℃) of filtration materials based on arselone fiber in thermal-oxidative atmosphere. Chemical composition of gas–dust, detained by textile bag filters on gas treatment stations of ferro-alloy plants, is examined. Efficiency of arselone textile material is analyzed in order to extract compounds of Cd, Pb, Mn, Zn, Cu, Cr, Al, Fe, Ca, and Mg from gas–dust.

A vacuum gauge based on an ultracold gas

We report the design and application of a primary vacuum gauge based on an ultracold gas of atoms in an optical dipole trap. The pressure is calculated from the confinement time for atoms in the trap. The relationship between pressure and confinement time is established from the first principles owing to elimination of all channels introducing losses, except for knocking out an atom from the trap due to collisions with a residual gas particle. The method requires the knowledge of the gas chemical composition in the vacuum chamber, and, in the absence of this information, the systematic error is less than that of the ionisation sensor.

Numerical prediction of the chemical composition of gas products at biomass combustion and co-combustion in a domestic boiler

In recent years the numerical modelling of biomass combustion has been successfully applied to determine the combustion mechanism and predict its products. In this study the influence of the addition of waste glycerin in biomass wood pellets on the chemical composition of exhaust gases has been investigated. The pellets have been prepared from spruceand pine wood sawdust without and with addition of waste glycerin. The waste glycerol is a undesirable by-product of biodiesel transesterification at oil manufacturing. The produced pellets were being burned in the 10 kW domestic boiler adapted to wood pellets combustion. The possibilities of pollutants generation (CO2 , CO, NOx SOx and compounds containing chlorine) in the exhaust gases coming from the boiler were numerically calculated using the latest version of CHEMKIN-PRO software, introduced by the American company Reaction Design. The results of the calculations correspond to the data obtained on a real object, in particular: combustion temperature, gas pressure, residence time of fuel in the burner, air flow, fuel consumption, as well as elementary composition of fuel supplied into the boiler. The proposed method of predicting the chemical composition of exhaust gases allows proper control of the combustion process and can be considered as an important step in reducing the pollutants (lower emission of NOx , SOx and CO2 neutral) and thus to contribute to the improvement of the environmental quality. In addition, knowledge of the amounts of Clbased compounds produced in combustion process (under given conditions), can serve as an important hint in terms of corrosion prevention of boiler- and chimney steels.

Curing kinetics, thermal and morphological characterization of the biobased thermosets from epoxy resin/epoxidized hemp oil

The paper presents the synthesis and thermal behavior of an epoxy matrix from diglycidyl ether of bisphenol A (DGEBA) and epoxidized hemp oil crosslinked with two hydroxy carboxylic acids (HAc). Epoxidized hemp oil (EHO) was obtained via epoxidation in situ with peroxyacetic acid. The chemical structures of hemp oil (HO), EHO and epoxy matrix were confirmed using FT-IR and 1H NMR spectroscopy. The kinetics of the curing reactions were studied by differential scanning calorimetry (DSC) using multivariate non-linear regression method from the “Thermokinetics-3” software (Netzsch). Also, the thermal decomposition behavior of network has been studied in nitrogen atmosphere up to 600°C using simultaneous TG/FT-IR/MS technique. Using the above software, the global kinetic parameters of thermal decomposition were determined and was found that the thermal decomposition process occurs in three steps. A good correlation was observed between experimental and simulated data. The chemical composition of gases that arise in the process of thermal decomposition was assessed using FT-IR and MS techniques.

Effect of inclusion of graded level of water hyacinth on in vitro gas production kinetics and chemical composition of alfalfa hay based beef cattle diets

The aim of this study was to evaluate the inclusion of water hyacinth (WH) as a possible substitution of alfalfa hay (AH) in diets of beef cattle on in vitro methane production, gas kinetics and chemical composition. AH in the diets was substituted by WH at 0% (T1, as a control), 25% (T2), 50% (T3), 75% (T4) and 100% (T5). Methane, CO2 and gas production parameters were recorded after 24 and 48h of incubation. NDF, condensed tannins and total phenolic compounds increased when AH was substituted. Likewise, the net gas production decreased linearly when AH was substituted. However, gas production rate among treatments were similar. Methane and CO2 production decreased linearly with inclusion of WH. These results indicate that WH arises as a promising alternative for mitigating methane production in ruminants.