Alexander Ilyushechkin - Academia.edu (original) (raw)

Papers by Alexander Ilyushechkin

Hydrogen

Hydrogen has been studied extensively as a potential enabler of the energy transition from fossil... more Hydrogen has been studied extensively as a potential enabler of the energy transition from fossil fuels to renewable sources. It promises a feasible decarbonisation route because it can act as an energy carrier, a heat source, or a chemical reactant in industrial processes. Hydrogen can be produced via renewable energy sources, such as solar, hydro, or geothermic routes, and is a more stable energy carrier than intermittent renewable sources. If hydrogen can be stored efficiently, it could play a crucial role in decarbonising industries. For hydrogen to be successfully implemented in industrial systems, its impact on infrastructure needs to be understood, quantified, and controlled. If hydrogen technology is to be economically feasible, we need to investigate and understand the retrofitting of current industrial infrastructure. Currently, there is a lack of comprehensive knowledge regarding alloys and components performance in long-term hydrogen-containing environments at industrial...

Inorganics

Metal alloys and intermetallic compounds offer an attractive method for safely storing hydrogen (... more Metal alloys and intermetallic compounds offer an attractive method for safely storing hydrogen (H2). The metal alloys absorb H2 into their structure, often swelling and fracturing as a result of phase transformation during hydride formation/decomposition cycles. The absorption of H2 is an exothermic process, requiring the effective and efficient removal of heat. This can be challenging as heat transfer to/from powdered beds is notoriously difficult, and often limited by poor thermal conductivity. Hence, the observed reaction kinetics for absorption and desorption of H2 is dominated by heat flow. The most common method for improving the thermal conductivity of the alloy powders is to prepare them into composite structures with other high thermal conductivity materials, such as carbons and expanded natural graphite. Such composite structures, some also combined with polymers/resins, can also mitigate safety issues related to swelling and improve cyclic durability. This paper reviews ...

$Research paper thumbnail of In Situ Synchrotron Powder Diffraction Studies of Reduction–Oxidation (Redox) Behavior of Iron Ores and Ilmenite$

Metallurgical and Materials Transactions B, 2017

Phase transformations of two types of iron-based oxides (iron ore and industrial-grade ilmenite) ... more Phase transformations of two types of iron-based oxides (iron ore and industrial-grade ilmenite) were studied using synchrotron powder diffraction of the samples processed in reducing and oxidizing atmospheres at 1173 K (900°C) and 1223 K (950°C), respectively. In iron ore oxidation, the disappearance of the wustite and fayalite phases was followed by hematite growth and a decrease of the magnetite phase. The magnetite phase was partially recovered by treatment in a reducing atmosphere. Ilmenite oxidation initiated decomposition of the ilmenite phase with rapid growth of hematite and gradual growth of the pseudobrookite phase. In a reducing atmosphere, ilmenite was gradually recovered from pseudobrookite with a relatively fast initial decrease in rutile and hematite content. Under reducing conditions, there was interaction of iron ore with magnesio-ferrites in iron ore-ash mixture and interaction of ilmenite with silica by the formation of fayalite.

Canadian Metallurgical Quarterly, 2014

Experimental studies have been carried out to determine phase equilibria in the Fe-Mg-Si-Al-Ca-Cr... more Experimental studies have been carried out to determine phase equilibria in the Fe-Mg-Si-Al-Ca-Cr-O system in air and in reducing atmospheres. The univariant lines between spinel and tridymite primary phase fields, and between the pyroxene and tridymite primary phase fields in the Fe-Mg-Si-O system with and without CaO, Al 2 O 3 and Cr 2 O 3 addition have been determined. The measurements demonstrate clearly that the presence of Al 2 O 3 and CaO in the system lowers the liquidus in the silica primary phase field. The study also confirms that lowering the oxygen potential in the system lowers the liquidus temperatures for Fe-Mg-Si-Al-Cr-Ca-O slags. On a effectué des é tudes expé rimentales afin de dé terminer les é quilibres de phases du systè me Fe-Mg-Si-Al-Ca-Cr-O à l'air et en atmosphè res ré ductrices. On a dé terminé les lignes univariantes entre le spinelle et les champs de phases primaires de la tridymite, et entre le pyroxè ne et les champs de phases primaires de la tridymite dans le systè me Fe-Mg-Si-O, avec et sans addition de CaO, d'Al 2 O 3 et de Cr 2 O 3. Les mesures dé montrent clairement que la pré sence d'Al 2 O 3 et de CaO dans le systè me abaisse le liquidus dans le champ de phase primaire de la silice. L'é tude confirme é galement que l'abaissement du potentiel d'oxygè ne dans le systè me abaisse les tempé ratures de liquidus des scories de Fe-Mg-Si-Al-Ca-O.

32nd European Microwave Conference, 2002, 2002

This paper presents results of development of high temperature superconducting (HTS) thick films ... more This paper presents results of development of high temperature superconducting (HTS) thick films for microwave components. Low cost thick film HTS technology was developed opening the possibility to implement 3-D superconducting structures of complex geometries covering variety of configurations typically used for waveguide microwave filters, diplexers, transitions and other components. Theoretical and practical aspects of this technique discussed including application

Chemical Engineering Journal, 2015

ABSTRACT Gasification of blends of biomass and coal can offer renewable fuels the scale and exten... more ABSTRACT Gasification of blends of biomass and coal can offer renewable fuels the scale and extent of deployment usually associated with fossil fuels. For significant penetration of renewables, however, co-utilization of significant quantities of biomass is required, which significantly impacts process performance. At a fundamental level, char reactivity affects many practical aspects of gasifier operation, and is complicated by the influence of blends of coal and biomass and their different behaviour during devolatilization. In this work, intrinsic gasification reaction kinetics of chars from biomass and coal mixtures with different proportions were studied: one set of chars produced separately and mixed prior to gasification; and another with chars produced from co-pyrolysis of biomass-coal blends. Lower specific and intrinsic rates were observed for the samples where the biomass and coal were pyrolyzed together than when they were pyrolyzed separately, suggesting some interaction during devolatilization that affects reactivity behaviour. XRD results showed that the catalytically-active calcium species in the biomass interacted with the aluminosilicate species in the coal mineral matter to form Ca2Al2SiO7 (gehlenite) crystals, which are catalytically inert. The conversion of catalytically-active Ca to catalytically-inactive Ca may have led to lower reactivity of co-pyrolyzed mixtures, highlighting the importance of understanding the type and nature of often catalytically-active species when investigating the gasification behaviour of blends of coal and biomass materials.

The behaviour of mineral matter is important for the characterisation of coal for use in entraine... more The behaviour of mineral matter is important for the characterisation of coal for use in entrained-flow gasification technologies. We investigated four behavioural characteristics—ash fusion temperatures (AFT), slag viscosity versus temperature profiles, temperatures of critical viscosity (TCV), and slag phase compositions—of Rhenish lignite coal ash using laboratory and modelling tools. Our modelling of AFT using coal ash composition provided a wide range of data, with only one (modified) model demonstrating agreement with experimental data. Experimental slag viscosity data were obtained over a temperature range from 1200uC to 1500uC. Where relevant, TCV was also measured. Comparison of these data to the calculated viscosities using several models from the literature revealed variation in the accuracy of the models due to the different databases used. Models that calculate TCV on the basis of ash composition fail to predict the data due to very high silica:alumina ratio. However, models based on AFT data match well with the experimental TCV values. The formation of solids in the slags in the temperature range below liquidus was calculated using thermodynamic modelling tools and compared with the microstructure of laboratory quenched samples. This revealed a strong relationship between solids formation and increasing viscosity. We also examined a modification of slagging behaviour by blending the Rhenish ash with ash of an Australian coal in different ratios. We show that greater viscosity and a wider operational temperature can be achieved by using an appropriate

Powder Technology, 2008

The importance of syngas cleaning has driven research in this area for over two decades but so fa... more The importance of syngas cleaning has driven research in this area for over two decades but so far a robust and completely reliable technology has not been developed especially for gas cleaning over 600°C to achieve higher efficiencies. The greatest evidence of this is continuation of research and development to improve particulate filtration, various sorbents and associated equipment. Although significant improvement has been made in these gas cleaning technologies in the past few years there still seems to be a long way to go to achieve complete reliability of these systems which have never been tested successfully in a real integrated gasification (IG) based system environment. The question then arises as to whether these conventional gas cleaning technologies will ever be perfected. This raises a few secondary questions such as what are the hurdles in the development of these technologies. Is there any fundamental limitation with the concept behind conventional gas cleaning technology? What are the practical problems these conventional technologies face and are unable to cope with? This paper summarizes the research conducted at the Centre for Low Emission Technology and CSIRO Energy Technology over the past year and presents a brief summary of current status of syngas cleaning technologies particularly of particulate removal systems and a review of practical problems and limitations faced by these gas cleaning systems. These problems have been qualitatively analyzed to evaluate if there is any link between these practical problems and fundamental limitations with the basic concept behind these gas cleaning technologies. Recommendations are also made to overcome these fundamental limitations.

Separation and Purification Technology, 2009

Nickel-zirconium-based amorphous alloys are promising hydrogen-selective membrane materials. Thes... more Nickel-zirconium-based amorphous alloys are promising hydrogen-selective membrane materials. These membranes can potentially be combined with a suitable water-gas-shift catalyst to form a catalytic membrane reactor, which can produce high-purity H 2 and CO 2 streams from coal-derived syngas at elevated temperatures. One shortcoming of amorphous alloys is that their temperature of operation is limited by the onset of crystallization, which in many cases occurs at a temperature below that demanded by typical WGS catalysts. It is hypothesized that the substitution of zirconium with other elements of higher bond valance will increase the crystallization temperature of these amorphous alloys. Systematic substitutions (M = Ti, Nb, Mo, Hf, Ta and W) have been made to the eutectic alloy Ni 64 Zr 36−X M X. Results have shown that niobium, hafnium and tantalum increase the crystallization temperature of these alloys, while Ti decreases the crystallization temperature. Mo and W are problematic in that they have limited solubility, and lead to brittle alloys that are unsuitable for the gas separation application. Of the alloys studied, those from the Ni-Nb-Zr system are most prospective for use in a hydrogen-selective catalytic membrane reactor. Hydrogen permeability studies of three alloys showed that partial substitution of Zr with Nb reduced permeability but improved the thermal stability. An increase in thermal stability not only increases the resistance to crystallization, but also reduces interdiffusion between the membrane and Pd catalyst. Thus, the operating temperature of Ni 64 Zr 36 membranes can be increased through partial substitution of zirconium with niobium.

Superconductor Science and Technology, 2000

Bi-2212 tapes were fabricated using a powder-in-tube method and their superconducting properties ... more Bi-2212 tapes were fabricated using a powder-in-tube method and their superconducting properties were measured as a function of heat treatment. The tapes were heated to temperature, T 1 (884-915 • C), and kept at that temperature for 20 min to induce partial (incongruent) melting. The samples were cooled to T 2 with a ramp rate of 120 • C h −1 and then slowly cooled to T 3 with a cooling rate, R 2 , and from T 3 to T 4 with a cooling rate, R 3. The tapes were kept at the temperature T 4 for P 1 hours and then cooled to room temperature. Both R 1 and R 2 were chosen between 2 and 8 • C h −1. It was found that the structure and J c of the tapes depend on the sintering conditions, i.

Materials Science and Engineering: B, 2010

Magnesium oxide nanoparticles embedded into Bi-2212/Ag tapes may significantly improve transport ... more Magnesium oxide nanoparticles embedded into Bi-2212/Ag tapes may significantly improve transport properties of the tapes in magnetic fields as flux pinning centres. The effect of the addition of ultra-fine MgO particles, obtained by Mg combustion, in Bi-2212/Ag tapes was investigated in order to improve critical current densities of the tapes in magnetic fields. Optimization of the MgO concentration and uniformity of the MgO particles distribution across the tapes were also investigated. Microstructure of Bi-2212 ceramic layer and J c of the tapes were enhanced with addition of MgO nanoparticles with concentrations of up to 4 wt.%. Higher MgO concentrations lead to degradation of the samples' microstructure and a corresponding decrease of absolute J c values in self-field.

Journal of Membrane Science, 2006

Catalytic membrane reactors, composed of a suitable hydrogen-selective membrane and water-gas-shi... more Catalytic membrane reactors, composed of a suitable hydrogen-selective membrane and water-gas-shift catalyst, can be used to produce a pure hydrogen stream from coal-derived syngas with high yield. The membrane must combine chemical and physical stability in the syngas environment at elevated temperatures, with rapid hydrogen permeation and low cost. Amorphous alloy membranes based on a combination of early transition metals