Gas Generation Research Articles

MATHEMATICAL MODELS OF THE THERMAL PROTECTION COATING OF THE GAS GENERATOR OF THE HYDROGEN STORAGE AND SUPPLY SYSTEM

The article describes the properties of the thermal protection coating of the gas generator of the hydrogen storage and supply system by two transfer functions with Hurwitz polynomials of the third order. Obtaining such transfer functions is based on the solution of the non-stationary heat conduction equation, represented in operator form using the integral Laplace transform, and in which approximating spline functions in the form of second-order polynomials are used. The article gives the solution of the non-stationary thermal conductivity equation, which describes the thermal processes in the heat-protective coating of the gas generator of the hydrogen storage and supply system under the thermal effect of a fire. This solution comes in the operator form for the surface temperature of the heat-protective coating on the side of the gas generator wall. The peculiarity of this decision is the presence of hyperbolic functions of an irrational argument in its composition. The structural and dynamic scheme of the thermodynamic system ‘gas generator wall – heat-protective coating’ is presented, the feature of which is the presence of two entrances. The signal at the scheme’s first input reflects the thermal effect of the fire, and the signal at the second input reflects the thermal state of the gas generator cavity. An equivalent mathematical transition to the description of thermal processes in the heat-protective coating of the gas generator of the hydrogen storage and supply system was carried out. This transition happened due to the use of spline functions, which approximate the hyperbolic functions of the irrational argument and are polynomials of the second order. The article gives a verbal interpretation of the algorithm for determining the transfer functions of the heat-protective coating of the gas generator of the hydrogen storage and supply system and also an example of its implementation. Furthermore, it shows that for the given conditions of functioning of the gas generator heat-protective coating, the relative errors in approximation of hyperbolic functions by second-order polynomials do not exceed 1.7 %, and the average relative error when equivalent replacement of transfer functions does not exceed 3.8 %. Keywords: gas generator, hydrogen storage and supply system, thermal protection coating.

Toward Sustainable Production: Emerging Trends in Iron and Steel Making

AbstractThe iron and steel industry is a significant contributor to greenhouse gas emissions, responsible for about 7–9 % of the total emissions. This paper examines sustainable production methods in the iron and steel industry, focusing on decarbonization strategies and energy integration. It covers a wide range of alternative reductants to replace the conventional use of coal. Moreover, the paper highlights the challenges and opportunities associated with each approach. Additionally, it discusses the design modifications for coal‐based sponge iron plants, aiming to reduce coal consumption and waste gas generation while ensuring economic viability. This study provides a roadmap for transitioning to environmentally friendly, technically feasible, and economically viable iron and steel manufacturing processes.

Coal chemistry, utilization potential, and coalbed methane (CBM) assessment of some coal deposits in Central Benue Trough, north-central Nigeria

Coalbed methane (CBM), a current global legislative priority for climate change mitigation, is an unconventional and eco-friendly clean source of energy that is considered a veritable alternative to conventional fossil fuels. Despite its overwhelming advantages, CBM evaluation studies of Nigerian coals have received little or no attention. To bridge the gap in knowledge, we have for the first time in Jangwa-Shankodi and Lafia-Obi, described the potential of harnessing CBM for its gainful utilization in Nigeria using some coal deposits in its north-central region as a case study. The gas contents of the coals were determined empirically by taking account of their ultimate and proximate properties. Other coal parameters such as fuel ratio and vitrinite reflectance (Ro (%)) have also been computed and discussed. Proximate analyses of the studied coal samples show moisture contents that vary between 2.28 and 2.56%, whereas, volatile matter yield is placed in the range of 29.98–30.34%. Ash yield ranges from 7.83 to 8.64%. Fixed carbon content varies from 55.97 to 56.30%. Variation in fuel ratio shows a restricted range from 1.72 to 1.87. All the coal samples were found to be low in sulphur (< 1%) with H/C ratios that vary from 0.072 (LAF 2, 3 and 4) to 0.086 (JSK 3). Moreover, the coals were found to be of medium-volatile bituminous rank, with gas contents that range from 12.65 to 13.20 cc/g. In the current study, kerogen lies in the Type IV zone, which suggests the generation of methane gas by the studied coal samples. Also the estimated range of vitrinite reflectance (Ro) which varies between 1.073% and 1.086% indicates thermogenic gas expulsion in the coals. There is a noticeable increase in gas content with coal maturity and depth. These values are indicative of good quality coals that show antecedents for CBM production. However, considering that this work is a pilot study, we recommend that core drilling be employed in obtaining insitu measurements of the coal gas contents and thus, verify these empirical estimates. Also, detailed laboratory study on pore structure (and its distribution) and adsorption isotherm curve are recommended to better understand the coal reservoir properties and hence, consolidate the present study.

PERIODIC FOAMING DURING SELECTIVE ISOLATION OF HIGHLY PERMEABLE CHANNELS OF POROUS MEDIUM

Selective isolation of watered interlayers by forming barriers formed by highly viscous gels or insoluble precipitates does not always lead to the desired results. Field experience confirms that at some distance from the formed barrier, the filtration flow restores its configuration and the water injected into the formation again moves through highly permeable channels. An increase in the efficiency of flow deflection can be achieved by creating not a single barrier, but a whole sequence of alternating deep-penetrating insulating barriers, separated from each other by a certain distance in highly permeable pores. The paper presents the results of studies of quasi-periodic foaming in order to control mobility under conditions of selective isolation of water in pore channels of high permeability. Foaming occurs due to the in-bulk reaction between concentrated aqueous solutions of gas-generating and gas-generating solutions. Flow pattern of injected aqueous solutions of foaming reagents along current tubes is investigated. The task is to determine the space-time distribution of reagents in given zones of the porous medium. The problem of establishing the correlation between the spatial distribution of the gas formation zone and the dynamics of the gas formation process over time on the one hand, as well as the concentration of reactants, the diffusion rate (mutual diffusion), the gas generation rate and the probability of nucleation on the other hand was solved. The degree of flow blockage in highly permeable zones of the formation depends on the rate of in-situ foam generation and the simulation consists in the fact that it is similar to the law of filtration with a limiting gradient. The paper discusses the process of quasi-periodic gas formation during the movement of mixing solutions in porous media. In stationary filtration in a homogeneous porous medium, the process is described by the proposed system of equations. A system of equations is proposed that describes the movement of a liquid taking into account adsorption of reagents, diffusion and dynamics of the foaming reaction. The results obtained can serve as the basis for developing a method for controlling the water cut of porous media during waterflooding of oil formations. This, in turn, leads to the leveling of the displacement front and an increase in the completeness of coverage.

Experimental study on heat transfer efficiency of pyrotechnics enhanced by gas generator

Experimental study on heat transfer efficiency of pyrotechnics enhanced by gas generator

Recognition of Artificial Gases Formed during Drill-Bit Metamorphism Using Advanced Mud Gas

Drill-bit metamorphism (DBM) is the process of thermal degradation of drilling fluid at the interface of the bit and rock due to the overheating of the bit. The heat generated by the drill when drilling into a rock formation promotes the generation of artificial hydrocarbon and non-hydrocarbon gas, changing the composition of the gas. The objective of this work is to recognize and evaluate artificial gases originating from DBM in wells targeting oil accumulations in pre-salt carbonates in the Santos Basin, Brazil. For the evaluation, chromatographic data from advanced mud gas equipment, drilling parameters, drill type, and lithology were used. The molar concentrations of gases and gas ratios (especially ethene/ethene+ethane and dryness) were analyzed, which identified the occurrence of DBM. DBM is most severe when wells penetrate igneous and carbonate rocks with diamond-impregnated drill bits. The rate of penetration, weight on bit, and rotation per minute were evaluated together with gas data but did not present good correlations to assist in identifying DBM. The depth intervals over which artificial gases formed during DBM are recognized should not be used to infer pay zones or predict the composition and properties of reservoir fluids because the gas composition is completely changed.

ADVANTAGES AND FEATURES OF USING DIGITAL TWIN TECHNOLOGY FOR STATIONARY GAS ENGINES

At the moment, there is no mass alternative to power plants based on an internal combustion engine. Such power plants are fully mastered in production, they are mobile, not bulky, and do not depend on weather conditions (wind, current, etc.), as required by wind and hydroelectric power plants. The variety and availability of fuels is also a very big advantage in favour of internal combustion engines. On the other hand, engines are a source of heat, noise and chemical pollution, and by running on fossil fuels, they contribute to negative climate change on the planet, so the issue of improving the fuel, economic and environmental efficiency of vehicle engines is relevant. With the rapid development of information technology, it is now possible to create a perfect control system for stationary engines using digital twin technology, which in the future could take over the entire task of controlling the unit with minimal human intervention, eliminating the effect of the human factor and thereby increasing the life and efficiency of the unit. The goal is to use the forecasting system to assess the actual technical condition of the engine and, based on this data, set the optimal maintenance intervals, as well as prevent accidents that entail expensive repairs or even complete replacement of the unit. Such a system would be relevant for large, expensive stationary machines involved in any technological processes where the unit's downtime entails financial losses associated with the cessation of a particular production process. Representatives of this type of power plant are gas engines - drives for booster or downhole gas compressors, gas generators operating on landfill gas or biogas.

Research on the Characteristics of Partial Discharge Gas Generation in Typical Defects of Oil Immersed Current Transformers

During the operation of oil-immersed current transformers, they gradually deteriorate due to various factors. In order to study the relationship between partial discharge and gas generation characteristics under different typical defects, this paper measures the unit-time discharge energy, unit-time apparent discharge quantity, pulse repetition rate, and gas generation rate during the discharge development process of three typical defects: protrusion defect, surface defect, and gas gap defect. The study reveals that the generation of hydrocarbon gases and hydrogen in the oil mainly depends on discharges with an apparent discharge quantity above 300pC. Among the discharge characteristics, the unit-time discharge energy and unit-time average discharge quantity significantly impact the gas generation rate. It is found that the content of C2H2 and C2H4 in the oil for protrusion and surface defects increases significantly with discharge intensity, while CH4 and H2 show significant changes for gas gap defects. Additionally, an approximately linear relationship exists between discharge energy per unit time, pulse repetition rate, and the rate of characteristic gas generation for both protrusion and surface defects, as well as for gas gap defects. These findings provide a reference for diagnosing current transformers and highlight the critical role of discharge characteristics in gas generation dynamics.

Physicochemical processes during solidification and the peculiarities of structure formation in aerated concretes using metallic silicon as a gas generator

The results of research on the structure and phase composition of non-autoclaved aerated concrete with a density of 550–750 kg/m3 using metallic silicon as a gas generator are presented. The peculiarities of the structure formation of aerated concrete products and the mineralogical composition of their hydration products were investigated. It was established that increasing the content of metallic silicon in aerated concrete leads to an increase in the pore space of the compositions. The results of diffractometric and thermal analysis methods for establishing the phase composition of aerated concrete compositions with metallic silicon as a gas generator are also presented. Analysis of XRD patterns and derivatograms showed that the aerated concrete samples under investigation contain a binder component, obermorite (5CaO6SiO25.5H2O); xonotlite (6CaO6SiO2H2O); -dicalcium silicate hydrate (2CaOSiO2H2O); and hillebrandite (2CaOSiO21.17H2O). It was established that increasing the amount of metallic silicon as a gas generator stimulates an increase in the content of hydrated phases in aerated concrete compositions.

Physicochemical processes during solidification and the peculiarities of structure formation in aerated concretes using metallic silicon as a gas generator

The results of research on the structure and phase composition of non-autoclaved aerated concrete with a density of 550–750 kg/m3 using metallic silicon as a gas generator are presented. The peculiarities of the structure formation of aerated concrete products and the mineralogical composition of their hydration products were investigated. It was established that increasing the content of metallic silicon in aerated concrete leads to an increase in the pore space of the compositions. The results of diffractometric and thermal analysis methods for establishing the phase composition of aerated concrete compositions with metallic silicon as a gas generator are also presented. Analysis of XRD patterns and derivatograms showed that the aerated concrete samples under investigation contain a binder component, obermorite (5CaO6SiO25.5H2O); xonotlite (6CaO6SiO2H2O); -dicalcium silicate hydrate (2CaOSiO2H2O); and hillebrandite (2CaOSiO21.17H2O). It was established that increasing the amount of metallic silicon as a gas generator stimulates an increase in the content of hydrated phases in aerated concrete compositions.

Physicochemical processes during solidification and the peculiarities of structure formation in aerated concretes using metallic silicon as a gas generator

Physicochemical processes during solidification and the peculiarities of structure formation in aerated concretes using metallic silicon as a gas generator

Study on the cracking process of epoxy resin under oxygen and water atmosphere based on ReaxFF force field

Amino-cured epoxy resins are widely used in the electrical and electronic industry for their excellent properties. To investigate the mechanism of the effect of O2 and H2O on the pyrolysis behavior of epoxy resin, in this paper, the cross-linked structure of bisphenol A type epoxy resin cured by adducts of diethylenetriamine and butyl glycidyl ether is modeled based on the ReaxFF force field, and the thermal decomposition processes at different temperatures and gas atmospheres were simulated and the pathways of the small molecule products were clarified. The results show that epoxy resin will produce small molecule gas products, such as H2, CO, H2O, OH, CH2O, and free radicals, in the process of pyrolysis; the presence of amino groups also generates nitrogen-containing radicals, such as CN, CH2N, and C2H4N; as the reaction temperature increases, the rate of pyrolysis reaction will be accelerated. The same temperature in oxygen and water atmospheres can accelerate the breakage of epoxy resin main chain by promoting the breakage of carbon and oxygen bonds and, at the same time, promote the generation of small molecule gases, such as H2 and CO.

The sewer advances: How to select eco-friendly pipe materials for environmental protection

Sewer pipe materials exhibit diverse inner-surface features, which can affect the attachment of biofilm and influence microbial metabolic processes. To investigate the role of the type of pipe material on the composition and metabolic capabilities of the adhering microorganisms, three sets of urban sewers (High-Density Polyethylene Pipe (HDPE), Ductile Iron Pipe (DIP), and Concrete Pipe (CP)) were constructed. Measurements of biofilm thickness and environmental factors revealed that the thickest biofilm in CP pipes reached 2000 μm, with ORP values as low as −325 mV, indicating a more suitable anaerobic microbial habitat. High-throughput sequencing showed similar relative abundances of genera related to carbon and sulfur metabolism in the DIP and CP pipes, whereas HDPE exhibited only half the relative abundance compared to that found in the other pipes. To explore the impact of pipe materials on the mechanisms of microbial response, a metagenomic approach was used to investigate the biological transformation of carbon and sulfur in wastewater. The annotations of the crucial enzyme-encoding genes related to methyl coenzyme M and sulfite reductase in DIP and CP were 50 and 110, respectively, whereas HDPE exhibited lower counts (25 and 70, respectively). This resulted in significantly lower carbon and sulfur metabolism capabilities in the HDPE biofilm than in the other two pipes. The stability of wastewater quality during the transmission process in HDPE pipes reduces the metabolic generation of toxic and harmful gases within the pipes, favoring the preservation of carbon sources for sewer systems. This study reveals the variations in carbon and sulfur metabolism in wastewater pipe systems influenced by pipe materials and provides insights for designing future sewers.

Investigation of Gas-Turbine Afterburner with Aluminized Fuel-Rich Propellant

This paper describes the design and development of a compact afterburner system for a mini gas turbine engine using aluminized fuel-rich propellant. The working principle of the system is analogous to a dual combustor ramjet engine in which the propellant is burnt in the primary chamber. Hot gases from the primary chamber combust further in the secondary chamber with incoming air from the inlet. In this work, fuel-rich gases were injected into the afterburner through radially mounted gas generators. The hot gases mix with the oxygen-rich turbine exhaust and burn further, resulting in high-enthalpy gases. These high-enthalpy gases were expanded in the convergent nozzle to generate higher exit velocity. This study investigated the thrust enhancement capability of the gas turbine afterburner system with fuel-rich propellant grains at different operating conditions. Furthermore, the effect of increasing afterburner length and decreasing nozzle exit diameter on the performance of the system was also examined. An overall static thrust of about 320 and 360 N was obtained for three and four grains, respectively, with maximum unburnt fuel residues of 11% in both the cases, out of which four grain configurations achieved a maximum thrust enhancement of around 180%.

Estimation of Boil-Off Gas Generation by using Phase-Field Model for Liquid Hydrogen Vacuum-Jacketed Valve

Estimation of Boil-Off Gas Generation by using Phase-Field Model for Liquid Hydrogen Vacuum-Jacketed Valve

Corrosion shielding effect of polyaluminium sulphate on metallic aluminium during the solidification of radioactive incineration bottom ash by low alkalinity cement

Radioactive incineration bottom ash containing metallic Al is difficult to be directly solidified in the cement matrix due to the generation of hydrogen gas during the reaction of aluminium with alkali pore solution of cement paste. In this study, the simulated incineration bottom ash (SIBA) containing metallic Al was successfully and directly solidified by polyaluminium sulphate (PAS)-modified low alkalinity cement (LAC), and the mechanism of the corrosion shielding effect of PAS on metallic Al was characterized by a range of analytical techniques. The results indicate that the cement waste form containing 29.56 wt% SIBA achieved a compressive strength of 16.6 MPa at 28 days of hydration, which increased by 13.3 % and 36.1 % after freeze-thawing test and immersion test, respectively. The 42d cumulative fraction leached of Nd3+ and Ce3+ were 1.74×10−7 cm and 3.40×10−7 cm, respectively. The corrosion degree and corrosion rate of Al sheets in LAC with PAS addition was much lower than that without PAS at early and late age hydration, by transforming thick porous corrosion layer to thin dense one. The mineral phase of corrosion product remained as bayerite (Al(OH)3), regardless of whether PAS was added. The addition of PAS reduced the hydrogen gas generation and prevented the dissolution of Al(OH)4- from metallic Al sheet. The hydrolysis of PAS produced a large amount of Al(OH)4- in pore solution, which extended the pH range for Al(OH)3 passivation by preventing the transformation of Al(OH)3 protection layer on the Al sheet surface to Al(OH)4- in the pore solution, and accelerated the formation of ettringite to decrease the pH of pore solution. This study cast the light on the direct solidification of metallic-aluminium-containing incineration bottom ash or Al bulks by cement-based materials without the need for complex pretreatment processes.

Experimental study on the mechanism of associated gas generation by heavy oil aquathermolysis and thermal cracking during steam injection

Previously, we proposed an innovative method for heavy oil recovery known as the ISSG-SAGD (in-situ solvent generation enhanced steam assisted gravity drainage) technique. This technology can improve heavy oil recovery efficiency, reduce steam consumption, and mitigate acid gas emissions. However, the reaction kinetic model used in numerical simulation was derived from literature reports and reasonable assumptions, lacking experimental validation. This study addresses this gap by conducting a series of experiments to investigate the mechanism of associated gas generation under steam injection conditions. We differentiated the reaction temperature window of aquathermolysis and thermal cracking based on the quantity and composition of the associated gas generated. The study revealed that aquathermolysis, occurring at 240–280℃, produces a small amount of associated gas (gasification degree of 0.32 %), predominantly CO2 (about 68 %). In contrast, thermal cracking, occurring at temperatures up to 380℃, significantly increases gas generation (gasification degree of 14.33 %), with light hydrocarbons (C1–5) constituting about 80 % of the gas produced. The reaction rate was found to be proportional to the reaction temperature and time. The SARA analysis showed that saturates and aromatics content increased, while resins and asphaltenes decreased after both reactions. A kinetic model for associated gas generation was established, and kinetic parameters such as activation energies and frequency factors were derived using the Arrhenius method. For example, the activation energy for CO2 generation increased from 18.19 kJ/mol during aquathermolysis to 147.58 kJ/mol during thermal cracking. This study provides a comprehensive understanding of the associated gas generation mechanisms and characteristics under steam injection, supporting the feasibility and potential application of the ISSG-SAGD technique in heavy oil recovery.

The Implications of Seeping Hydrocarbon Gases in the Gunsan Basin, Central Yellow Sea, off the Southwest of Korea

A detailed analysis of high-resolution (3.5 kHz) chirp seismic profiles acquired in the Gunsan Basin of the central Yellow Sea revealed that hydrocarbon gases are actively seeping via the formation of many plumes. The uppermost sedimentary layer was acoustically confirmed to be fully or partially charged with gases. Somewhat favored by the low-tide period, episodic gas seepage is mainly associated with the underlying fault systems of Cretaceous-Cenozoic sedimentary strata in the southwestern part of the basin. Catastrophic gas expulsion seems to have formed a crater at the sidewall of a sedimentary ridge and two diapirs. Here, methane is poorly concentrated but rich in the heavy carbon isotope (δ13C, −52.6‰ to −44.7‰ The Vienna Peedee Belemnite [VPDB]), indicating that methane formed mainly through biodegradation of heavy oils at depth remains in the shallow sediments following its expulsion. Episodic rapid upward advection of porewater is also manifest by unmixed heavy methane trapped in the upper part of the primary biogenic methane (δ13C, about −90‰ VPDB)-filled sediment core. These findings imply that the Gunsan Basin fulfills the requirements for possible generation and preservation of oil and gas, like the petroliferous basins of eastern China and the Yellow Sea.

Investigations of thermochemical fluids as cleanup system for polymer-based fracturing fluids

The cleanup of fracturing fluids, involving polymer degradation and well flowback, is crucial for the success of the fracturing operations and revenue generation. Breakers, such as oxidizers and enzymes, are commonly employed to break down polymers, resulting in lower viscosity, improved flowback, and facilitated well cleanup. However, these conventional breakers, which contribute solely to the cleanup process through polymer degradation, have some drawbacks, such as premature breaking and insufficient release of breakers. In this study, thermochemical fluids (TCFs) are proposed as a cleanup system. This system can improve the cleanup process by lowering viscosity through temperature increase and thermal degradation of polymers, reducing hydrostatic pressure via gas generation, and eliminating phase trapping damage in tight reservoirs through the heat produced. The TCFs investigated in this study were NH4Cl and NaNO2 solutions, where a substantial amount of heat was determined from the thermal energy study using an autoclave reactor. In this study, the thermal degradation of guar gum (GG) polymer derivatives, hydroxypropyl guar gum (HPG), and carboxymethyl hydroxypropyl guar gum (CMHPG) were assessed using Fourier Transform Infrared Spectroscopy (FTIR), Thermal Gravimetric Analysis (TGA), viscosity measurements, and coreflood experiments. Both FTIR and TGA analyses of linear gels of GG and its derivatives confirmed alterations in the chemical and thermal properties of these polymers following thermal treatments. The coreflood results showed a regained permeability of 87% for thermally treated HPG borate-crosslinked, 96% for CMHPG dual crosslinked (borate and zirconate), and 90% for slickwater fracturing fluids, respectively. The regained permeability of thermally treated slickwater was even better than that for slickwater with ammonium persulfate breaker.

Numerical and experimental study of energy absorption in multilayer tubes manufactured through spinning forming process under quasi-static axial loading

Currently, dual-layer tubes play a pivotal role in sectors like nuclear, oil, gas, and steam generation. Recent research focuses on enhancing energy absorption in these tubes using the spinning forming process. This thin-walled nature benefits their application as efficient energy absorbers in transportation like trains and aircraft. A novel approach integrates coarse and fine-threaded ridges between steel and aluminum layers to create a mechanical interlock using the spinning forming technique. This interlock enhances the bond through flow forming, resulting in robust dual-layer tubes. Interlayer connection strength is rigorously tested through shear tests, pre and post flow forming, indicating a significant post-flow forming enhancement. This process substantially bolsters the overall structural integrity of dual-layer tubes. In crush tests, both single-layer and dual-layer steel and aluminum tubes undergo pressing through flow forming. Comparative analysis of energy absorption parameters—specific energy and crushing percentage—reveals notable performance differences. An annealed version of the tube with an aluminum layer is also included due to prior aluminum layer failures. Among dual-layer samples, the flow formed variant with fine-threaded ribs exhibits superior energy absorption and bonding. Finite element simulation of the pressed dual-layer sample demonstrates an 8.42 % deviation between simulated and experimental energy absorption outcomes. The study highlights that tightly bonded layers result in enhanced bonding characteristics.