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Plasma was generated in the focal region of a multikilowatt, 4.7-GHz continuous-wave (CW) microwave beam far removed from the walls of the vacuum chamber, minimizing the nonideal effects associated with plasma–wall and beam–wall interactions. Experiments were conducted with gas mixtures of argon, nitrogen, and oxygen at gas pressures ranging from 100 to 200 mtorr. Three types of discharges were observed during these experiments: unstable, quasi-stable, and stable discharges. It was determined that the stability of the discharges could be controlled through adjustments of the gas composition, gas pressure, and power of the microwave beam. This article reports on the operational conditions in which stable discharges were achieved and the general behavior of these discharges as the control parameters were varied.

—To study the kinetics of the processes occurring in the region where a plasma torch interacts with high-chromium Kh18N10-steel-type iron melts, we investigate the influence of the partial nitrogen pressure in a plasma-forming gas on the decarburization when the melts are processed by an oxidizing plasma in a laboratory setup at a variable oxidation potential. A computer program for processing experimental data is developed. It takes into account the process of inert gas dilution of evolved carbon monoxide and dioxide with allowance for the true character of gas evolution. The kinetic parameters of the plasma decarburization of the high-chromium melts are determined, and the influence of the partial pressures of oxygen and nitrogen in the plasma-forming gas on the process kinetics is detected. The mechanisms of limiting the interaction at various stages of the process are proposed. The influence of nitrogen on the oxidative decarburization in a plasma furnace is studied. The presence of nitrogen in the plasma-forming gas composition is shown to decrease the rate and degree of carbon removal from the melts.

In this paper, we studied the interrelation between the variations in CH4, CO, CO2, NO, NO2, O3, and SO2 concentrations, and the number concentration of aerosol with particle diameters larger than 0.4 μm, and the following meteorological parameters: air temperature, atmospheric pressure, wind direction and speed, total solar radiation and ultraviolet radiation in the wavelength range 295–320 nm, relative humidity, and partial water vapor pressure. For this, we used the air composition monitoring data (for the period 1993–2018) from the Tropospheric Ozone Research (TOR) station in the region of Tomsk Akademgorodok.

The results of integrated studies in the southwestern part of the Sea of Okhotsk obtained during cruise 74 of the R/V Akademik M.A. Lavrentiev in 2016 are presented. Gas hydrates, carbonate crusts and nodules in bottom sediments and more than 100 gas flares in the water column were recognized. Great attention has been paid to the gas composition of the water column and bottom sediments. Anomalous concentrations of hydrocarbon gases, helium, and hydrogen were revealed in the Kuril Basin–Terpeniya Bay transition zone.

This work presents a numerical and experimental investigation of sawdust gasification in a fluidized bed using air. The fluidized bed reactor was tested in the Faculty of Engineering, Mansoura University, Egypt. In the experimental part, the experiments were made in a fluidized bed gasifier to optimize the gasifying of sawdust pellets using air. The syngas composed mainly of CO, H2, CH4, and CO2 as in the typical gasification process. The obtained experimental results showed that the syngas contents are strongly affected by the equivalence ratio and temperature. Increasing of ER improves char burning to produce more CO2, but H2 gradually increased till ER = 0.35 instead of CH4, CO and H2 increased as temperature increased. The temperature of 900 °C and an equivalence ratio of 0.35 is the right combination of sawdust gasification as operating conditions. A kinetic-hydrodynamic one-dimensional model was developed and validated with experimental results. This model is used to expect the effect of various operating parameters on a biomass gasification performance, such as temperature, equivalence ratio, and different hydrodynamic parameters. This model capable of expects the axial gas composition along the gasifier, as well as the syngas composition and heating value of produced gas and the gasification efficiency at the reactor outlet. The model results were in reasonable agreement with experimental results and published results.

Although thermal conductivity gas analyzers are ubiquitous in industry, shrinking the sensing unit to a microscopic scale is rarely achieved. Since heat transfer between a metal nanoparticle and its ambient gas changes the temperature, refractive index, and density of the gaseous surrounding, one may tackle the problem using a single nanoparticle's photothermal effect. Upon heating by a 532 nm laser, a single gold nanoparticle transfers heat to the surrounding gas environment, which results in a change in the photothermal polarization of a 633 nm probe laser. The amplitude of the photothermal signal correlates directly with the concentration of binary gas mixture. In He/Ar, He/N2, He/air, and H2/Ar binary gas mixtures, the signal is linearly proportional to the He and H2 molar concentrations up to about 10%. The photothermal response comes from the microscopic gaseous environment of a single gold nanoparticle, extending from the nanoparticle roughly to the length of the gas molecule's mean free path. This study points to a way of sensing binary gas composition in a microscopic volume using a single metal nanoparticle.

The study applies a new technique for evaluating the NOx concentration when burning syngas in the gas turbine combustion chamber. The technique allows correlating the complete detailed mechanism of the Grimech 3.0 array of parallel reactions with the computer hydrodynamics equations (motion, heat and mass transfer, turbulence, and molecular diffusion equations for an ideal gas flow). Selectivity diagrams of the NOx formation process including eleven key reactions are built based on the specific reaction rates for lean and rich fuel mixtures. Verification calculations have been performed based on a model gas turbine combustion chamber within a fuel-air equivalence ratio of 0.5–2. The new technique has been applied for determining the NOx emissions and the maximum temperature of the industrial combustion chamber fire tube wall. The GE gas composition showed the best NOx emission result. The most problematic is Polk Power and Texaco syngas (oxygen process). When burning LCV gases in the primary air suction area, a recirculation zone is observed; due to the high heat release in this area, the maximum wall temperature is about 500 °С.

The effects of gas composition and the extent of reduction on the compressive strength of direct reduced iron (DRI) were investigated. Gas mixtures containing different proportions of hydrogen, carbon monoxide, water vapor, carbon dioxide and methane were tested. The structure of laboratory and industrial DRI was examined and correlated with gas composition and mechanical properties. After reduction, structural changes accompanying reduction and carburization were investigated with scanning electron microscopy, swelling was measured, and phases were quantified by X-ray diffraction. The major strength loss occurred in the first reduction step, when hematite grains transformed to porous magnetite. Carburization after reduction had a minor effect on strength, except when extensive precipitation of elemental carbon caused lower strength, similar to the metal dusting corrosion mechanism. Higher strengths were obtained when water vapor was added to the reducing gas.

Supercritical water gasification (SCWG) of mixtures of guaiacol and acetic acid was carried out in a continuous reactor at 600 °C and 25 MPa with a residence time of 94 s. Different concentrations of acetic acid were employed to investigate the effect of acetic acid on product yield and gas composition. The interaction between guaiacol and acetic acid during SCWG was discussed. Acetic acid, as a radical scavenger, was found to inhibit radical polymerization, resulting in the suppression of char formation.

The considerable decline of conventional oil and gas reserves and respectively their production introduces new challenges to the energy industry. It resulted in the involvement of hard-to-recover reserves using advanced enhanced oil recovery (EOR) techniques. Thermal methods of EOR are recognized as most technically and commercially developed methods for the highly viscous crude oil. High-Pressure Air Injection (HPAI) is one of the thermal production methods that reduce oil viscosity and increases recovery. HPAI has already been effectively applied for different types of reservoirs development and proven to be economically feasible. The application performance of the HPAI technology strongly depends on the quality of experimental and numerical modeling conducted on the target object basis. Before the field tests, physicochemical and thermodynamic characteristics of the process were studied. Further consequent numerical modeling of laboratory-scale oxidation experiments and field-scale simulation was conducted to estimate HPAI method feasibility based on the results of oxidation studies. A medium pressure combustion tube (MPCT) oxidation experiment was carried out to provide stoichiometry of the reactions and field design parameters. A 3D numerical model of the MPCT experiment was constructed taking into account the multilayer design, thermal properties, heating regimes, and reaction model. The “history” matched parameters such as fluid production masses and volumes, temperature profiles along the tubes at different times and produced gas composition demonstrated good correspondence with experimental results. The results obtained during the experiment and modeling of MPCT (fluid properties, relative phase permeability, kinetic model, technological parameters) were used in field-scale modeling using various thermal EOR scenarios. Air breakthrough into production wells was observed, thus a 2 % oxygen concentration limit where implied. The overall performance of four different scenarios was compared within 30 years timeframe. The development system was also examined to achieve the maximum economic indicators with the identifications of risks and main uncertainties.

The paper describes a block for calculating the Earth’s natural atmospheric radiation in the IR range developed for the general circulation model simulating the lower and middle atmosphere. This block uses the new parametrization of molecular absorption in the frequency range from 10 to 2000 cm−1 at the altitude ranging from the Earth’s surface to 76 km. The algorithm for constructing this parametrization takes into account the change in the gas composition of the atmosphere with altitude and has some other significant advantages. In addition, for the numerical solution of the radiation transfer equation, the discrete ordinate method and the computational zenith angle grid with the step of about nine degrees are used. The results of the line-by-line calculations of the Earth’s internal atmospheric radiation field are compared with the results of the calculations performed using parametrization, and it is shown that the presented parametrization is accurate in the lower and middle atmosphere both in the absence of clouds and in the presence of cloud layers with a significant optical thickness.

In May 2017, The University of Texas Hydrate Pressure Coring Expedition Gulf of Mexico 2-1 (UT-GOM2-1) drilled two adjacent holes in Green Canyon Block 955 in the deep-water Gulf of Mexico as part of The University of Texas at Austin and US Department of Energy Deepwater Methane Hydrate Characterization and Scientific Assessment. Expedition operations included testing two configurations of a rotary pressure-coring tool in a gas hydrate–bearing formation. In the first hole, an extended core barrel (cutting shoe) configuration of the Pressure Coring Tool with Ball Valve (PCTB-CS) was deployed, and in the second hole, the PCTB face bit configuration (PCTB-FB) was deployed. The PCTB-CS successfully recovered and maintained pressure for only one core out of eight deployments. A series of incremental modifications were made during and after the PCTB-CS deployment period that impacted the operations of the subsequent PCTB-FB deployments. Thus, in the second hole, the PCTB-FB successfully recovered and maintained pressure within the hydrate stability zone for 11 cores out of 13 deployments. The PCTB cored gas hydrate–bearing sandy silt interbedded with non–hydrate-bearing clayey silt within the main reservoir. The PCTB also recovered long intervals of unbroken, high-quality core with preserved sedimentary structures. We recovered one pressure core 130 m (437 ft) above the main hydrate reservoir in the silty clay. Pressure coring is the only available technology for recovering intact cores from sediment that is normally disturbed by gas expansion, dissolution, or dissociation; this allows a wide range of scientific measurements to be obtained with minimal disturbance to the core sediment fabric. Analysis of pressure cores has the potential to illuminate the in situ properties, gas saturation, and gas composition of a wide range of reservoirs including unconventional shale systems.

Arc discharge synthesis has industrial relevance due to its low cost and scale-up potential. The production of titanium nitride nanoparticles was achieved by direct current arc discharge in an atmospheric-pressured ambient composed of N2 and Ar. We systematically investigated the effect of the synthesis parameters, including quench gas velocity, quench gas composition, and applied arc current, on the particle quality, yield, and size. It is found that increasing quench gas velocity enables to produce particles with a primary size of 10–15 nm, while titanium nitride particles of 20–50 nm are produced at low quench gas velocity based on scanning electron microscope (SEM) analysis. X-ray diffraction (XRD) results indicated that titanium nitride particles produced at various nitrogen compositions are almost stoichiometric, while the crystallite size increases almost 20 nm when increasing nitrogen contents in the quench gas. Quench gas composition also has a significant impact on the arc voltage as well as particle production rate. When increasing the nitrogen concentration from 20% to 100%, the production rate can be enhanced by a factor of three. Besides, raising the applied arc current from 12 A to 50 A leads to a yield enhancement of factor 10. According to the Brunauer-Emmett-Teller (BET) measurement, the increase of applied arc current has a limited impact on primary particle size. The enhancement in particle production rate is mainly reflected by the larger agglomerate sizes and agglomerate number concentration. Additionally, based on experimental observations and previous studies, a mechanism is presented to explain the growth of deposits on the cathode tip.

The results of a numerical experiment to determine the thermal impact of a gas well cluster on permafrost rocks are given for the conditions of four deposits of Central Yakutiya, Middle-Vilyuy (Srednevilyuiskoe), Middle-Tyung (Srednetyungskoe), Sobolokh–Nidzhili (Sobolokh-Nidzhilinskoe), and Tolon–Mastakh (Tolon-Mastakhskoe). An approximate mathematical problem is solved in a conjugate formulation. In this case, the process of melting of permafrost rocks is described within the framework of a three-dimensional Stefan problem, and the motion of real gas in wells is described within the framework of tubular hydraulics. Use has been made of real data for temperature well logging, formation pressure and temperature, well flow rate, gas composition, and thermophysical properties of rocks. The melting of frozen rock depending on the depth and time has been calculated, and instants of time for linkage of thaw zones of neighboring wells have also been computed.

In the case of a severe accident in a Light Water Reactor, the issue of late release of fission products, from the primary circuit surfaces is of particular concern due to the direct impact on the source term. CsI is the main iodine compound present in the primary circuit and can be deposited as particles or condensed species. Its chemistry can be affected by the presence of molybdenum, and can lead to the formation of gaseous iodine. The present work studied chemical reactions on the surfaces involving gaseous iodine release. CsI and MoO3 were used to highlight the effects of carrier gas composition and oxygen partial pressure on the reactions. The results revealed a noticeable effect of the presence of molybdenum on the formation of gaseous iodine, mainly identified as molecular iodine. In addition, the oxygen partial pressure prevailing in the studied conditions was an influential parameter in the reaction.

The extraction of olive oil generates great amounts of solid waste and wastewater. The objective of this work is to evaluate the potentiality of slow pyrolysis of the solid oil waste, known as “orujillo”, to produce hydrogen rich gases. The effect of temperature and of different treatments of pyrolysis vapors on the yield and composition of the gases has been experimentally studied. “Orujillo” was pyrolyzed at 500 °C and 700 °C, and the pyrolysis vapors produced were directly fed to a second reactor where they were treated at 800 °C in different ways: just thermally, thermally treated through a refractory alumina bed and thermo-catalytically treated through a three layer bed (alumina + SiC mixed with Ni catalyst + alumina). The catalyst used was a commercial prereduced nickel-catalyst which contains 44 wt% Ni over calcium aluminate support (CaO/Al2O3). Concerning the effect of temperature, it has been proved that the raise in temperature leads to a decrease in the liquid yields and an increase in the gas yields, as well as to an increase in H2 and a decrease in CO2 content of the gases. With respect to the vapors treatments it has been observed that as a general rule any of the treatments reduces liquid and increases gas yields, and concerning gas composition, H2 content increases, CO slightly increases and CO2 decreases. These effects are more pronounced when the Ni-catalyst is used. With the Ni-catalyst about 50 wt% gas yield is obtained, with ≈ 50 vol% H2 both at 500 and at 700 °C.

Iron ore reduction is a primary unit operation in current metallurgy processes and dominates the energy consumption and greenhouse gas (GHG) emissions of the iron-making process. Therefore, even a slight improvement of the energy efficiency or GHG emissions of iron ore reduction would yield considerable benefits to the cost of pig iron and, more importantly, to mitigation of the associated carbon footprint. The current study presents a discrete model that describes the iron ore reduction process for a single pellet. The transient reaction progress can be predicted and is validated against experimental measurements under various operating conditions, including different reducing gases and temperatures. The effects of pressure, isothermality, gas composition, and flow rate on reduction are investigated. The reduction rate increases significantly with increasing pressure until 5 atm, and the entire reduction process occurs more slowly under non-isothermal conditions than under isothermal conditions. This work provides a solid foundation for the development of a comprehensive particulate system model that considers both heat and mass transfer.

A 25 kWth, fixed, perforated bed, downdraft gasifier was used to investigate and compare its performance for using corn cob (CC) and coconut shell (CS) — a proven fuel for gasification as feedstocks. Air was used as a gasifying medium and had been administered inside the gasifier reaction zone (just above the throat) through four equally spaced conduits in forced circulation mode. Gas composition, higher heating value (HHV) of gas, specific gas generation (SGG), and gasification efficiencies had been compared for CC and CS by varying the equivalence ratios (ERs) from 0.1–0.45. HHV of gas generated upon the gasification was inferred to be maximum at an ER of 0.3 while using CC (4.578 MJ/m3) and that of 0.35 for using CS (4.229 MJ/m3) as feedstocks. SGG — associated with maximum HHV of gas — was observed to be 2.12 m3/kg and 3.05 m3/kg for CC and CS, respectively. Optimal cold gas efficiency was obtained at the best operating point, i.e., at ERs of 0.3 and 0.35 for CC (62.83%) and CS (72.74%) gasification, respectively. Tar contents of 1.3 g/m3 and 0.62 g/m3 and particulate matter contents of 0.355 g/m3 and 0.215 g/m3 were quantified for the producer gas generated from CC and CS gasification, respectively.

Plasma technology finds applications in many industrial areas. To improve the process efficiency, different plasma forming gases and their mixtures are used. Since CO2 is economical and has high thermal conductivity, it is identified as a potential candidate in plasma material processing. However, the characteristics and merits of CO2 plasma arc in material processing are scanty. In this work, a 2D model is built to simulate plasma arc with CO2 and its mixtures with Ar. Effects of arc current, gas composition and arc length on the arc heating efficiency and arc characteristics are discussed. The arc size is strongly influenced by the gas composition at 200 A than at 100 A. Temperature distribution in the arcs is wider when CO2 content is decreased. The effect of arc current on the arc heating efficiency is stronger at lower current. Results predicted by the present model are compared with measured data for model validation.

A study of the composition of fluid inclusions in ore minerals of the Davenda Mo–porphyry deposit and the Aleksandrovskoe sulfide–quartz–gold ore deposit, as well as of fluid inclusions in minerals of igneous rocks, showed that ore-forming fluids inherit the salt and gas composition of magmatic fluids generated during crystallization of ore-bearing rocks of the Amudzhikan–Sretensky Igneous Complex, which formed simultaneously with the Au and Mo mineralization. The gold-bearing sulfide–quartz veins of the Aleksandrovskoe deposit formed with the participation of two types of hydrothermal fluids, differing in the composition of salts and the gas phase: homogeneous Ca–Na chloride fluids with CO2 and heterophasic Na–K–Fe-chloride fluids, which indicates two sources of ore-forming fluids during the formation of Au-mineralization. Na–K–Fe-chloride fluids in terms of salt and gas composition were similar to the ore-forming fluids of the Mo-mineralization of the Davenda deposit. Ore-forming Ca–Na-chloride with CO2 The fluids of the Aleksandrovskoe field are comparable in salt and gas composition with the magmatogenic fluids of quartz diorite porphyries and diorite porphyrites. Ore forming Na–K–Fe carbonate-chloride fluids of the Davenda and Aleksandrovskoe deposits show great similarity in composition to magmatic fluids of granite porphyry and emphasize the genetic identity of Mo mineralization in both deposits. The data obtained confirm the widespread opinion that a genetic relationship exists between gold mineralization and dikes of intermediate and mafic composition, and molybdenum–porphyry mineralization with granite–porphyry of the Amudzhikan–Sretensky Igneous Complex. The real agents of this genetic link are metalliferous magmatogenic fluids, the salt and gas composition of which inherit ore-forming fluids. The formation depth of productive ore mineral assemblages in veins of the Aleksandrovskoe and Davenda deposits is estimated at 7.9–7 and 8–6.3 km, respectively, which is not typical of porphyry deposits, the formation of which is characterized by shallower depths.

Research subject. We studied PT conditions, composition and sources of ore-forming fluids of the Bolshoy Karan goldporphyry deposit (South Urals) confined to the Main Urals Fault zone at Southern Urals. Methods. Temperatures of ore mineral formation, salt composition and fluid salinity were estimated using a Linkam TMS-600 cryostage equipped with an Olympus BX 51 optical microscope. The gas composition of fluid inclusions was determined using a Horiba LabRam HR800 Evolution Raman spectrometer and an Olympus BX-FM optical microscope. Trace elements were detected by means of LA-ICP-MS analysis. С and О isotopic composition was identified using a MAT 253 (Thermo Fisher Scientific) mass-spectrometer. S in the minerals of sulphide-carbonate-quartz ores was identified using a Delta PLUS Advantage mass-spectrometer. Results. It is shown that the fluid inclusions in quartz are homogenized at 370–310oC, while those of the latest calcite – at 234–200oС. The fluids contain Mg-Na chloride solutions with a salinity of 3.0–11.9 wt % NaClэкв. According to LA-ICP-MS data, quartz contains high Al contents (916–1556 ppm) confirming its formation from a high aluminous acid fluid. The REE distribution spectra in calcite are characterized by the accumulation of light lanthanides (La N /Yb N = 3.4–9.11) pointing to the acid fluid composition, as well as by negative Ce (0.58–0.88) and positive Eu (1.51–3.61) anomalies. The negative Ce anomaly may have been caused by interactions between the fluid and host limestones. The positive Eu anomaly reflects the existence of a middle-temperature environment (>250oC) prior to calcite crystallization. Y/Ho values in calcite (29.3–35.6) suggest the presence of magmatic components and those extracted from limestones. The values of δ 18 О in calcite vary from 14.7 to 19.8‰, while those of δ 13 С – from –4.1 to 0.7‰. The values of δ 18 О H 2 O for the ore-forming fluid, which were calculated based on average homogenization temperatures of fluid inclusions in calcite (230oС), vary from 6.5 to 11.5‰, while δ 13 С СO 2 – from –3.21 to 1.6‰. δ 34 S values in pyrite ranged from –0.60 to – 1.50‰. Conclusions. Our data confirm the formation of the gold-porphyry mineralization of the Bolshoy Karan deposit under mesothermal conditions. Magmatic fluids played the key ore-formation role. The geochemical peculiarities of interactions between the fluid and host rocks were revealed.

Scheelite coating was deposited on SiC fiber tows from various liquid-phase precursors at 1100℃. Strength degradation of SiC fiber was found after fiber coating which was found to be caused by the stress corrosion as a result of gases generated from the decomposition of by-products remaining in the coating. A new and simple method of low temperature pre-heat treatment was adopted to eliminate the stress corrosion in the fiber coating process and to isolate the effect of different types of gases on the stress corrosion cracking of fibers. The tensile strength and fractography of samples with and without pre-heat treatment were compared. Furthermore, the effect of gas composition on the strength degradation of SiC fiber was also investigated through the control experiments.

Here, the stability of stainless steel 316 (SS-316) was investigated to identify its applicability in the oxide reduction process, as a component in related equipment, to produce a complicated gas mixture composed of O2 and Cl2 under an argon (Ar) atmosphere. The effects of the mixed gas composition were investigated at flow rates of 30 mL/min O2, 20 mL/min O2 + 10 mL/min Cl2, 10 mL/min O2 + 20 mL/ min Cl2, and 30 mL/min Cl2, each at 600℃, during a constant argon flow rate of 170 mL/min. It was found that the corrosion of SS-316 by the chlorine gas was suppressed by the presence of oxygen, while the reaction proceeded linearly with the reaction time regardless of gas composition. Surface observation results revealed an uneven surface with circular pits in the samples that were fed mixed gases. Thermodynamic calculations proposed the combination of Fe and Ni chlorination reactions as an explanation for this pit formation phenomenon. An exponential increase in the corrosion rate was observed with an increase in the reaction temperature in a range of 300 ~ 600℃ under a flow of 30 mL/min Cl2 + 170 mL/min Ar.

The main advantage of standard gas sampling methods is their capability to keep a consistent gas composition from sampling till analysis. On the other hand, the disadvantages include the price and possible fragility of the sampling equipment, and the speed of sampling. Thus, a new tool was required that should have low cost, could be used for fast sampling and during fieldwork. Disposable plastic syringes fulfil all these requirements with the additional advantage that they can be used multiple times to take gas samples. With the utilisation of 3-way stopcocks, a filter media and a butterfly needle, a simple but efficient sampling system was prepared. Even though the holding time of certain components is not as high as it is for a standard sample holder, the precise analysis of the gas samples is possible. Syringes have been successfully utilised in the field of applied pyrolysis, for small and pilot scale experiments, and can even be used in industrial environment.

The subtidal kelp Nereocystis luetkeana (hereafter Nereocystis) maintains an upright stature by producing a single gas-filled float (pneumatocyst) that provides buoyancy. The ability of Nereocystis pneumatocysts to inflate with gas underwater is peculiar, and the gas composition of pneumatocysts has been the topic of several studies over the last 100 years. Past studies of pneumatocyst gases only examined large sporophytes, leaving open questions about the origins of these gases and how gas composition may change during development. In this study, we use developmental time as a means to understand the origin and physiological mechanisms that give rise to different gases within Nereocystis pneumatocysts. Total gas composition was measured across a range of pneumatocyst sizes (5-725 mL). Contrary to previous studies that documented pneumatocyst gas concentrations to be similar to air, this study found internal gas levels of CO, CO2 , and O2 to be 1.2 ± 0.8%, 0.6 ± 0.2%, and 59.9 ± 13.6%, respectively. Our data suggest that the composition of gases does not change as pneumatocysts grow and that the rate of each gas added is approximately proportional to changes in pneumatocyst volume. Therefore, cells constituting the pneumatocyst wall are likely producing more gas (per surface area) to fill pneumatocysts as they expand, maintaining proportional gas composition and corresponding internal pressure.

Актуальность исследования следует из необходимости оценки динамического уровня жидкости в нефтедобывающих и водозаборных скважинах с необходимой частотой. Измерения уровня жидкости в скважинах различного назначения необходимы для контроля разработки нефтяной залежи, оценки эффективности воздействия на продуктивный пласт и обеспечения безаварийной эксплуатации глубинного скважинного насоса. Информация об уровне жидкости востребована несколькими службами нефтегазодобывающего предприятия, а выполнение таких измерений может рассматриваться как одна из функций интеллектуальной скважины. Цель: поиск и обоснование альтернативных методов определения уровня жидкости в межтрубном пространстве нефтедобывающих и водозаборных скважин. Измерения должны проводиться с необходимой периодичностью без привлечения персонала предприятия в скважинную зону. Объектом исследования являются нефтедобывающие и водозаборные скважины, снабженные датчиками давления, генераторами и приемниками акустических волн, и вторичными приборами по передаче скважиной информации на рабочие места персонала предприятия. Методы исследования основаны на общеизвестных законах физической гидродинамики и методах математической статистики. В результате исследования установлено, что звукометрический метод определения динамического уровня жидкости в межтрубном пространстве скважины имеет погрешность измерений в действующих нефтедобывающих скважинах из-за непостоянства состава попутного нефтяного газа по времени эксплуатации скважины и по глубине насосно-компрессорных труб на фиксированный момент времени. Предложены альтернативные методы измерений, основанные на генерации акустических волн в различных средах и измерении давления в межтрубном пространстве по датчикам на стационарной основе. The relevance of the research follows from the need to assess the dynamic level of liquid in oil producing and water wells with the necessary frequency, which can be provided as one of the functions of an intelligent well. The aim of the research is to search for alternative methods for determining the liquid level in the annulus of wells without involving personnel in the well zone. Objects: oil producing wells equipped with pressure sensors, generators and receivers of acoustic waves and secondary instruments for transmitting information to the workplaces of the personnel of the enterprise. Methods: based on the well-known laws of physical hydrodynamics and methods of mathematical statistics. Results. The soundometric method for determining the dynamic liquid level in the annulus of a well has an error in measurements in existing oil wells due to the inconstancy of the composition of associated petroleum gas in time and in the depth of the tubing at a fixed point in time.

The ironmaking blast furnace (BF) is an energy-intensive process, requires a considerable amount of carbon-related materials such as coke, coal, or natural gas, and releases enormous amounts of greenhouse gas (GHG). The oxygen enrichment operation is one promising technology to reduce the carbon footprint in the ironmaking process. However, the oxygen enrichment ratio (OER) varies significantly in practices, and the proper one is still unclear, especially in terms of fuel rate saving and in-furnace phenomena. In this study, a multi-fluid BF model is used to quantitatively study the influence of oxygen enrichment on the BF process in terms of bosh gas volume, top gas composition, and inner thermochemical behaviors of solid–gas–liquid phases. Under the simulation conditions, the results show that for every increase of OER, the blast rate is decreased by ~ 85 m3/min and nitrogen content in reducing gas is decreased by ~ 1.13 pct; also, the top gas temperature is lowered by ~ 17 K, and the flame temperature is increased by 58.4 K. Descending of cohesive zone (CZ) inside the BF is observed with the region volume ratio decreased by ~ 0.102; the chemical reserve zone of wustite becomes much narrower and lower inside the BF, but does not disappear. The potential of carbon footprint mitigation in the BF process is discussed with the optimal OER recommended, 7.5 pct under the present simulation conditions. This model can help to build a comprehensive understanding of the fuel rate saving and CO2 emission reduction of a BF adopting an oxygen enrichment operation.

The effect of nitrogen addition and heat input on weld metal microstructure and mechanical properties of alloy 316 is studied. Autogenous gas tungsten arc welding (GTAW) is employed by adding up to 2 vol‌.% N2 in Ar. Welding speed and heat input rate are measured as functions of gas composition. Weld defects are examined by radiographic testing, and weld metal microstructure is studied by optical microscopy. Mechanical properties of welds are determined by uniaxial testing, hardness measurements, and bending test. Weld dendritic structure is refined by increasing N2 content in Ar. The mechanical properties and cooling rate are lower with increasing heat input. Besides, adding nitrogen to argon shielding gas leads to higher values of the ultimate tensile strength and hardness. The tensile strength, yield stress and elongation percent of welds depends strongly on the heat input and nitrogen content of shielding gas. This is discussed on the basis of microstructural characterization. Moreover, the weld nugget area, cooling time and solidification time increase with increasing heat input and nitrogen content. Finally, after applying the bending test up to 180o no cracks, tearing or surface defects could be observed on welded samples.

Plasma discharges are sustained in the focus of a continuous, high-power microwave beam. The experimental design minimizes interactions between the chamber walls and both the microwave beam and the resulting discharges so as to approximate free-space conditions. Discharges were generated by a multikilowatt, 4.7-GHz CW microwave beam at pressures ranging from 100 to 200 mtorr. The CW source enabled the evolution of the plasma-beam system to be observed over time scales ranging from seconds to hours. A variety of discharge behaviors are observed depending on the conditions (power, pressure, and gas composition) within the chamber. The observed discharges can be classified into three discharge modes: unstable, stable, and quasi-stable. Here, we present observations and a preliminary analysis of the various discharge modes observed in the experiment.

This paper presents the influence of welding current, electrode-workpiece distance, electrode composition, electrode diameter, electrode tip angle, shielding gas composition, and pulsed current frequency over the arc stagnation pressure of gas tungsten arc welding (GTAW). In this study, arc application tests were carried out over a 1-mm diameter hole on a non-melting water-cooled copper plate. The hole was connected to a differential pressure sensor through an extension tube. As a result, the welding arc pressure was observed to be directly proportional to the square of the welding current and to the tungsten electrode diameter. Moreover, the pressure increases as the electrode-workpiece distance is reduced, and it is inversely proportional to the electrode tip angle, for angles greater than 45°. Also, the electrode composition, the pulsed current frequency, and the gas composition influence the welding arc stagnation pressure.

Catalyzed gasoline particulate filters (cGPFs) are one of the most promising technologies to meet future stringent gaseous and particulate emission limits for gasoline-powered vehicles. The successful adoption of this technology relies on several important properties including high filtration efficiency, low back-pressure, high conversion efficiency, and great durability compliance. Particularly in this work, the conversion efficiency and durability of model cGPF catalysts were studied under different feed temperatures and multicomponent feed gas mixtures. The samples consisted of soot-free and real soot-loaded GPFs coated with noble metals supported on alumina and Ce-Zr mixed oxides. Prior to testing, the samples were subjected to diverse hydrothermal aging conditions. Some physicochemical characterization techniques, including scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), transmission electron microscopy (TEM), and nitrogen physisorption, were employed to study the fundamental relations between the state of the samples and their catalytic properties. The results showed that the introduction of soot appeared to have both a positive and negative effect on the catalyst activity. The catalyst surface is masked by the introduction of soot, blocking active sites and inhibiting species conversion. At the same time, the exothermicity of the soot oxidation reaction increases the catalyst temperature, reducing the light-off temperature, for the severely aged samples. Besides the presence of soot, the catalyst aging considerably influences the reactions over cGPFs. In particular, the conversions of ethylene and toluene were more affected by the catalyst aging than CO, which became even worse in the presence of NO in the feed gas. The formation of side products (NH3 and N2O) over the cGPFs was also examined under diverse practical conditions.

A novel multilayer perceptron artificial neural network (MLP-ANN) model is proposed to estimate the dew-point pressure (DPP) of gas condensate reservoirs as a function of gas composition, reservoir...

A CDF model for simulating gas dynamics, heat and mass transfer in the freeboard of a pilot-scale Rotary Hearth Furnace (RHF) is developed in conjunction with an independent solid reduction model a...

In this publication, the performance of a slurry bubble column reactor (SBCR) and a tube bundle reactor (TBR) are compared for steady-state and transient Power-to-Gas (PtG) operation. Transient PtG conditions are modeled using gas load step changes between 25 and 100% of the reactor maximum capacities in 1 s. For steady-state operation the TBR facilitates much higher gas hourly space velocities ( G H S V ) as compared to the SBCR. A sensitivity analysis shows that the TBR is limited by heat transfer, while the SBCR is limited by gas/liquid mass transfer. For transient PtG operation the TBR undergoes significant temperature changes within a short time resulting in out of specification product gas qualities and unacceptable temperature hot spots; the SBCR temperature shows marginal changes upon transient operating conditions, and the outlet gas composition sticks to the gas quality requirements. Finally, measures to improve the efficiency of both reactors are proposed considering dimensionless numbers. The G H S V of the SBCR can be enhanced by increasing the specific interfacial area controlling gas/liquid mass transfer, while the transient behavior of the TBR can be improved by reducing the catalyst concentration/activity or by mixing the catalyst with high heat capacity inert material in detriment of the G H S V .

Biomass combustion performance is greatly affected by the particle size distribution, which influences heat and mass transport phenomena. The present work investigates the effect of woodchip size distribution on combustion in a 140 kW underfeed stoker boiler. Three different fuel sizes were prepared, and their combustion performance was measured by monitoring temperatures inside and above the fire pit and the gas composition above the fuel bed. The gas composition was then correlated to the particle mean diameter. Although minor effects could be detected in the temperature and composition of the flue gases, a more uniform spatial distribution of volatiles was observed when employing bigger woodchips. The present results can improve the understanding of the impact of fuel size on the performance of woodchip-fired boilers and can be valuably used for numerical model validation.

Residues from agriculture and forest maintenance (lignocellulosic waste biomass) create a huge source of renewable energy and valuable materials. Gasification of this waste provides combustible gases consisting mainly of H2, CO and CO2, which can be used as syngas feed for methanol synthesis after treatment. Oxygen, steam or their mixtures can be used as gasifying agents in the biomass to methanol process. One of the most important parameters with crucial effect on gas composition and reactor temperature is the gasifying agent to feed mass flow ratio. In this work, gasification process of two samples of mixed agricultural waste, gas treatment and synthesis of methanol from the syngas produced was designed and simulated in the Aspen Plus environment. Three different cases were investigated: (1) only oxygen as gasifying agent, (2) oxygen and steam as gasifying agents without steam recycling and (3) oxygen and steam as gasifying agents with steam recycling. Samples of mixed agricultural waste consisted of corn leaves and stalks, wheat straw, barley straw, sunflowers and wood chips were characterised by proximate, ultimate and calorimetric analysis. Oxygen and steam flows were optimised to achieve maximum theoretical yield of methanol while maintaining the gasifier temperature, equal to, at least 900 °C. The best methanol to biomass ratio (MBR) of 0.43 was reached for a sample with lower moisture and ash content when both oxygen and steam were used as gasifying agents. The optimal oxygen to biomass ratio (OBR) was 0.57, and the steam to biomass ratio (SBR) was 0.89.

The highly selective conversion of H2S–CO2 to syngas (a mixture of H2 and CO), which assisted by non-thermal plasma and MoS2/Al2O3 hybrid system, was obtained at low temperature and atmospheric pressure. The effects of reaction conditions, including the specific energy input (SEI), feed flow rate, feed gas composition (H2S/CO2 molar ratio), and MoS2 loading were carefully investigated. The 50-h-long runs indicate that MoS2/Al2O3 was stable in the course of simultaneous H2S–CO2 conversion into syngas with excellent reaction properties. High CO2 conversion (>60 %) and almost full H2S conversion (98–100 %) can be achieved. The non-thermal plasma combined with MoS2/Al2O3 offers a novel and energy-efficient strategy to produce syngas from concomitant H2S–CO2 acid gases with great value for detoxifying H2S and reducing CO2 emissions.

Membranes are a critical technology for energy-efficient separation processes. The routine method of evaluating membrane performance is a permeation measurement. However, such measurements can be limited in terms of their utility: membrane microstructure is often poorly characterized; membranes or sealants leak; and conditions in the gas phase are poorly controlled and frequently far-removed from the conditions employed in the majority of real processes. Here, we demonstrate a new integrated approach to determine permeation rates, using two novel supported molten-salt membrane geometries. In both cases, the membranes comprise a solid support with laser-drilled pores, which are infiltrated with a highly CO2-selective molten carbonate salt. First, we fabricate an optically transparent single-crystal, single-pore model membrane by local laser drilling. By infiltrating the single pore with molten carbonate, monitoring the gas–liquid interface optically, and using image analysis on gas bubbles within the molten carbonate (because they change volume upon controlled changes in gas composition), we extract CO2 permeation rates with exceptional speed and precision. Additionally, in this arrangement, microstructural characterization is more straightforward and a sealant is not required, eliminating a major source of leakage. Furthermore, we demonstrate that the technique can be used to probe a previously unexplored driving force region, too low to access with conventional methods. Subsequently, we fabricate a leak-free tubular-supported molten-salt membrane with 1000 laser-drilled pores (infiltrated with molten carbonate) and employ a CO2-containing sweep gas to obtain permeation rates in a system that can be described with unprecedented precision. Together, the two approaches provide new ways to measure permeation rates with increased speed and at previously inaccesible conditions., The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement 320725 and the Engineering and Physical Sciences Research Council (EPSRC) via Grants EP/M01486X/1, EP/P007767/1, and EP/P009050/1. Greg A. Mutch thanks the EPSRC for his Doctoral Prize Fellowship (EP/M50791X/1) and Newcastle University for a Newcastle University Academic Track (NUAcT) Fellowship. Financial support from the Spanish Ministerio de Economía y Competitividad and FEDER Funds under Project MAT2016-77769-R is acknowledged.

This paper presents an enhanced gas chromatography–mass spectrometry method for the separation of cell gases in polyurethane foam. The novel method was then tested on several polyurethane foams produced at different mixing times, showing successful results. The measurement of gas content in polyurethane foams has been rarely considered in published literature. This parameter, indeed, plays a critical role in the deterioration of polyurethane foam thermal conductivity. This is because of the diffusion of gases which is the main mechanism of foam aging. Hence, an improved gas chromatography–mass spectrometry method was developed to offer simultaneous separation of several types of gas in only one column, using gas chromatography as its main concept. The composition of a sample gas consisting of N2, O2, CO2, and C5H10 was accurately calculated by measuring the ratio of each peak area on the chromatograms, with argon being used for sampling. This fast and simple method was found to be useful, on one hand for the accurate determination of C5H10 and CO2 cell gases used as blowing agents, and on the other hand for N2 and O2 air gases that diffuse rapidly from the surrounding environment into foam cells. The effect of mixing time on foam kinetics, cellular structure, foam thermal conductivity, and the overall thermal conductivity of cell gas mixture was also investigated. By complex analysis of foam density, the presence of open cells, cell size, and thermal conductivity of cell gas mixture, the lowest measured value of foam thermal conductivity was explained. The major goal of these experiments was to show the importance of foam cell gas analysis, together with foam structure, which is uniquely done to contribute to the understanding of polyurethane foam thermal conductivity. The thermal conductivity of cell gas mixture is considered as an example of the potential applications of this novel gas chromatography–mass spectrometry method.

Pyrolysis is an effective coal-upgrading method by converting low rank coals (LRCs) to thermal-efficient and environmentally friendly fuels together with many other valuable products. Compared to wall heat pyrolyzer, gas heat carrier pyrolyzer is expected to be more stable in performance. In this paper, a mathematical model is used to describe the multiphase flow related to the pyrolysis of LRC ellipsoidal briquettes in a gas heat carrier pyrolyzer at industrial-scale. The model is validated against the practical measurements in terms of components distribution of gas products. The comprehensive in-furnace phenomena during the pyrolysis are illustrated, in terms of flow, temperature, gas composition, and pyrolysis characteristics. The simulation results indicate that the opposite-positioned gas inlets lead to weak gas flow along chamber centreline, and results in the non-uniform temperature distribution in the bed. The ellipsoidal briquettes in the lower part of bed show a better pyrolysis performance compared to the upper part because of the stronger interphase heat transfer. Then the effects of particle shape on pyrolysis efficiency are examined by comparing ellipsoidal and spherical particles. It is indicated that in the upper bed where the gas velocity is relatively low, the spherical raw coal particles show better pyrolysis efficiency compared to ellipsoidal briquettes. This model provides a cost-effective way to understand and optimise the pyrolysis practice of gas heat carrier pyrolyzers.

A comprehensive 3D CFD model has been developed for analyzing thermal conversion of woody biomass fuel in a large reciprocating grate boiler under air/oxy-fuel condition. A number of sub-models representing solid conversion processes such as drying, devolatilisation and char combustion, gas phase flow and chemical reactions, solid and gas phase interaction through heat and mass transfer and bed movement is included in the model by user defined subroutines. The model has been validated by simulating a moving grate furnace from literature and comparing results with this reference experimental study. In this work, wet woody biomass fuel combustion is investigated under different oxy-fuel condition. Three different oxy-fuel cases have been investigated with 25% O2 (OF 25), 27% O2 (OF 27) and 30% O2 (OF 30) concentration by volume in the feed oxidizer gas with CO2 as recycled flue gas. Furnace operating condition is varied by changing air mass flow and inlet oxidizer gas composition, but all other operating conditions and furnace thermal load were kept constant. The effect of O2/recycled flue gas (CO2) ratios on flame temperature distribution, species concentration, char burnout and fuel consumption have been studied in detail and substantial differences were noticed comparing with the air-fired case. The numerical prediction showed that, gas temperature profile OF 25 case is closer to the referenced air fired combustion. The gas flame temperature has increased with O2 concentration rise, reaching maximum temperature at OF 30 case. CO2 concentration was increased to almost three times than air fired case due to use of CO2 in the feed gas. Increased CO2 concentration in the furnace has augmented char combustion rate and fuel consumption. Maximum fuel consumption was observed for OF 30 case where the fuel bed distribution over the grate was found minimum. Therefore, biomass bed combustion under oxy-fuel condition can provide better flame temperature and char burning to improve combustion condition.

The presence of H2S and CO2 is unfavorable in many processes and flows, particularly in natural gas flows. Therefore, removing this gas is one of the important issues in many systems. One of the most widely used techniques is the use of membrane. Therefore, the gas that passes through the membrane has low pressure. Membrane system is used to absorb a high volume of CO2. The factors needed for this kind of separation include gas composition, pressure, and temperature difference. An enhanced electrochemical membrane can also be used with coal gas to separate acid gases. Hydrogen is so rich in this process in which cathode and sulphur steam are produced and then exited. Granular activated carbon (GAC) can be used as supporting material to absorb H2S. The advantages of this method are including high capacity for H2S absorption and gas emission. Removing the H2S from waste gases or natural gas with high densities is done via bio-filter in this system. Granular activated carbon can be used as a supporting material to stabilize the microorganisms. Principal properties of the supporting material are including the mass density, the area of special surface, and the amount of its pH. This research discusses the membrane technology in removing the acid gases in the oil technology. © 2020 by SPC (Sami Publishing Company), Reproduction is permitted for noncommercial purposes.

Blast furnace (BF) dust is a typical solid waste produced in manufacturing iron, which can be recycled effectively through in-flight reduction technology. In this work, the gas-molten reduction behavior of BF dust particles during in-flight process was analyzed experimentally and mathematically. The experimental results shown that the effects of temperature and gas composition on the reduction degree were significant. The morphological observation found that the dust particle was completely melted down at 1723 K and the generated metallic iron was entrapped and aggregated into a perfect sphere in the molten particle. The kinetic analysis revealed that the reduction process is controlled by the chemical reaction at the gas-molten interface and the activation energy was determined to be 246 kJ/mol. A computational fluid dynamics (CFD) model was also developed to study the fluid flow, heat transfer and chemical reactions involved in the reduction process, where the reduction gas was treated as a continuum and the dust particles were tracked by Lagrangian approach. A recirculation zone and a low gas temperature region were predicted near the top part region of the reactor. The accurate particle residence time was calculated by solving particle motion equations with the introduction of particle relaxation time. Non-isothermal particle temperature profiles inside the reactor were obtained, and were taken into consideration for the chemical reactions. The simulated terminal reduction degrees agree well with the experimental results.

High efficiency purification of dust particles contained in industrial flue gas is urgently needed to mitigate environmental pollution and improve waste heat recovery efficiency. The agglomeration and growth behavior of dust particles has significant effects on filtration efficiency of industrial flue gas. In this paper, in order to reveal the microscopic mechanism of dust particles agglomeration and growth, three kinds of typical components in industrial flue gas, such as steam (H2O), PAHs (naphthalene) and dust particles (SiO2) were selected to establish a molecular dynamics (MD) simulation system. The agglomeration behavior of dust particles and the formation and growth process of dust clusters were characterized by MD simulation. The effects of temperature, channel width, cooling rate and gas composition on the agglomeration behavior of dust particles and the growth of dust clusters were investigated. It is found that the formation and growth of dust clusters are driven by agglomeration of dust particles. The decrease of gas temperature, cooling rate and channel width can accelerate the agglomeration of dust particles and the growth of dust clusters, which is beneficial to dust particles filtration. In addition, the hydrogen bonds formed between the H2O molecules and SiO2 particles can promote the adsorption of SiO2 particles to the H2O molecules, which is also beneficial to the formation and growth of dust clusters. So increasing the content of steam in industrial flue gas is helpful to the growth of dust clusters and the filtration of dust particles.

Introducción: En procesos de gasificación en lecho fluidizado, es importante evaluar el comportamiento de parámetros de presión, temperatura, composición de gas, características del material a gasificar, flujo de oxidante, entre otros, para llevar a cabo esta evaluación rápidamente, el uso del modelado mediante dinámica de fluidos computacional es una de las herramientas más poderosas. Las fases sólida y gaseosa de la gasificación pueden estimarse mediante el uso un modelo Lagrangiano y Euleriano respectivamente. Objetivo: Desarrollar un modelo mediante el uso de la dinámica de fluidos computacional para la evaluar el comportamiento del proceso de gasificación en lecho fluidizado. Metodología: A partir de la revisión de la literatura, se seleccionó la geometría del reactor a modelar, las condiciones de operación y el material a gasificar. Se describe detalladamente el modelo desarrollado con el software STAR CCM+, las ecuaciones que rigen el comportamiento del proceso, los estudios de independencia de malla y tiempo entre otros parámetros de interés. Resultados: Se validó el modelo desarrollado con datos reportados en la literatura mediante comparación directa de las concentraciones del gas obtenido cuando se utilizó aire como agente oxidante, así mismo, se muestra la concentración del gas obtenido a lo largo del reactor para tiempos de interés. Conclusiones: A partir de los resultados obtenidos, se logró una buena aproximación con lo reportado en la literatura, lo que permite evidenciar la validez del modelo desarrollado. Los submodelos utilizados en este trabajo difieren de los reportados por [1], por lo que se obtiene algunas diferencias en las fracciones molares de las especies obtenidas, no obstante el modelo predice adecuadamente el comportamiento del proceso.

The growing demand for energy raw materials and the ongoing implementation of restrictions on emissions of pollutants have caused considerable intensification of research on alternative fuels. Among them, syngas seems to be an especially promising option to use for electricity generation. Due to the fact that syngas is mainly composed of hydrogen and carbon monoxide, which are both flammable gases and the latter of which is also toxic, its uncontrolled release can pose a serious hazard. The paper presents the processes involved in syngas production from coal and biomass with respect to the produced gas composition. An analysis is carried out of potential effects of a syngas release from the pipeline to the environment, such as a jet fire, an explosion and formation of a toxic gas cloud. Hazard zones arising around a damaged synthesis gas pipeline are determined. The size of the zones depends on the gas composition and is generally much smaller in the case of a release of syngas obtained from biomass gasification. It also depends on the degree of damage to the pipeline. The created hazard zone is the biggest if the pipeline is ruptured completely.

Introduction. When using personal protective equipment for respiratory organs of an insulating type in case of depletion of a regenerative cartridge, hypoxic-hypercapnic changes in the gas composition of the body occur, which have a negative effect on the tolerance of personal protective equipment for respiratory organs. The combination of additional respiratory resistance with hypoxia and hypercapnia further worsens the tolerance of respiratory protective equipment. The purpose of this study was to study the tolerance of personal respiratory protection when changing the gas composition of the alveolar air. Material and methods. The study was conducted on healthy subjects of both sexes (78 people), aged 20 to 36 years. To simulate the conditions for the use of personal respiratory protective equipment, inspiratory resistive respiratory loads of 20% of the maximum intraoral pressure were used during the Mueller test. The tolerance of respiratory protective equipment was evaluated using the Borg visual analog scale of dyspnea, which reflected the level of subjective discomfort occurring due to additional respiratory resistance is turned on. The methodology for changing the gas composition of the alveolar air in the subjects consisted of using a system that allowed adding oxygen from the line to the closed spirograph circuit and turning the carbon dioxide adsorber on and off. Results. The tolerance of personal respiratory protection is associated with the nature of the gas composition of the alveolar air. A minimum of subjective discomfort was observed in the presence of hyperoxic-hypocapnic composition of the pulmonary air; on the contrary, an increase in subjective discomfort on the Borg scale was observed with a reduced oxygen content and an increased concentration of carbon dioxide. The use of personal respiratory protective equipment against the background of hypoxia-hypercapnia negatively changes the functional state of the body: there was observed an increase in physiological expenditures by leading effectors. Normalization of the gas composition of the body under the use of personal respiratory protection did not lead to complete optimization of the functional state of the subjects. Conclusion. Hypoxia and hypercapnia arising from the depletion of regenerative cartridges of the respiratory protective equipment of an insulating type leads to a significant deterioration in the tolerance to additional respiratory resistance. The alleged mechanism of this phenomenon should be considered as an increase in fatigue of the respiratory muscles.