Feasibility Study of an Iron-Based Composite Added with Al2O3/ZrO2 as an Oxygen Carrier in the Chemical Looping Applications

The chemical looping process is a promising approach for carbon capture. Oxygen carriers play the crucial role of carrying oxygen between oxidation and reduction reactors. In this study, iron-based composites, added with alumina and zirconia, were used as the oxygen carriers. The feasibility study of these composites for chemical looping applications was then evaluated by measuring their properties, including mechanical properties, relative density, microstructures, crystal structure, and their capacity of oxygen. The results suggest that the addition of zirconia led the decrease of the bulk relative density and thus had a negative effect to both crush strength and attrition. Crush strength declined from 57 kgf to 26 kgf when using zirconia, replacing alumina, in an iron-based composite as the inner material. In addition, the phases in oxidizing and reducing reaction were also revealed. The formation of the spinel phase (FeAl2O4) was the major factor that altered the capacity of oxygen. It inhibited Fe2O3’s ability to be completely reduced to Fe and thus decrease the capacity of oxygen. The value was therefore decreased from 9.7% to 6.2% after 50 redox cycles in alumina addition composite. On the other hand, for the zirconia addition, all of the Fe2O3 could transform to Fe, which provided 8.5% of oxygen capacity after 50 redox cycles. A dense layer which was identified as the Fe2O3 in the bulk surface was observed in the samples reacted with 50 redox cycles. The proposed mechanism of the formation of Fe2O3 layer and its corresponding kinetic analysis was also revealed in this study.

Study on the Spacer Grid Dynamic Crush Strength According to Cell Sizes

A spacer grid is one of the primary components of the PWR nuclear fuel. Spacer grid maintains proper pitches between the fuel rods and enables the fuel rod to cool down by providing coolant flow path. However, when the nuclear fuel is subjected to an unexpected excessive load during shipping, handling, manufacturing and operating, it could lead to fuel failure such as spacer grid buckling and cladding tube deformation. The most limiting load acting on the spacer grid is the lateral impact load during seismic/loss-of-coolant accidents. Dynamic crush strength of the spacer grid greatly contributes to the nuclear fuel integrity throughout the fuel lifetime [1]. This buckling strength tends to become weak in end of life (EOL) condition. KEPCO NF (KNF) carried out dynamic crush tests of the spacer grid and analyzed its characteristics. Spacer grids were prepared with three groups that have different cell sizes according to beginning of life (BOL), EOL and enlarged EOL simulated conditions. In addition, two kinds of dynamic crush tests were performed. One is pendulum impact test that drops a hammer to the grid in a short time. And the other is hydraulic long-pulse test that pushes impact plate to the grid in longer time. These tests and analysis results were compared in each group and discussed to explore key factors for improving crush strength of the spacer grid. In this paper, the spacer grid manufactured by additive manufacturing (AM) technology [2] is also introduced to verify the buckling performance. AM is a method to make designed shape with metal powder and built-up technology that is different from conventional manufacturing. Through the study, it could be a good alterative solution that the new manufacturing method might be helpful to improve dynamic impact characteristics.

Study of the fractional composition of granulate influence on the performance indicators of tablets based on salmonellosis bacteriophag

The author presented experimental data on the influence of technological factors on the quality indexes of tablets based on a cryoliofilized salmonella bacteriophage. The analysis of the technological properties of model granules with such parameters as bulk density, flow ability, vibration compacting index, Hausner index, Сarr's index showed that the fractional composition of the granules should contain no more than 33 % of the pulverized fraction (0,25 mm or less). The granulate, regardless of its fractional composition, has elastic-plastic properties characterizing the strength of the tablets. The influence of the pressing pressure of the cryoliofilized composition tablets with salmonella bacteriophage on the crush strength and disintegration of enteric-soluble tablets was studied. The optimum compression pressure of tablets within 60 mPa of granules with a content of pulp fraction (0.25 mm or less) is not to be higher than 33 %.

Enhancement of processability, surface, and mechanical properties of paper based on rice straw pulp using biopolymers for packaging applications

Two biopolymers, chitosan and oxidized starch, were used as wet-end additives to improve the strength properties of the paper because of their biodegradable and non-hazardous qualities. The present study reports the improvement in surface and strength properties of packaging-grade paper made with rice straw pulp using biopolymers, chitosan, oxidized starch, and surface sizing added at the wet end of the paper machine. Use of chitosan at all doses from 0.5 to 10 kg/ton enhanced important surface and strength properties of paper. The breaking length, tear index, burst index, ring crush strength, stretch, tensile energy absorption index, and Taber stiffness of the paper with 10 kg/ton of chitosan as a wet-end additive showed 22%, 14%, 20%, 59%, 16%, 44%, and 48% improvement, respectively, in comparison to control, (i.e, without its addition). The Cobb60 was also reduced by 45%, showing better resistance to water in comparison to rice straw paper alone. The effects of chitosan added at the wet end on the paper surface were investigated using Fourier transform infrared spectroscopy (FTIR). The use of 10 kg/ton of chitosan at the wet end reduced the color and total suspended solids in the back water of the papermaking system by 55% and 51%, respectively. Further enhancement in the surface and strength properties of paper was observed following surface sizing with oxidized starch.

The Effects of Carbon Content on ZrCO Microspheres Prepared by Internal Gelation Process with Carbon Black

ZrCO ceramic microspheres were fabricated by sol-gel combined with carbothermic reduction. The effect of carbon on the physicochemical characteristics of the microspheres was investigated. The results indicated that with the increase of carbon content in the broth, the interior structure of the sintered microspheres would become loose, which led to the lowering of the density and the decreasing of crush strength of the ZrCO microspheres. Crack-free ZrCO ceramic microspheres with the high mass fraction of ZrC could be successfully obtained with C/Zr = 3 in the broth sintered at 1550°C for 4h in argon containing 5%CO.

Preparation of Porous Cylindrical Tubes Substrates from Zeolite and Clay for TiO2 Photocatalyst Coating

Titanium dioxide (TiO2) is the one of photocatalyst materials that widely used for decolorization of organic compounds in wastewater by photocatalytic mechanism which can be activated by UV light. Unfortunately, in the case of fine TiO2 power, filtration of the powder after water treatment process is difficult. In this research, coating or immobilizing the TiO2 powder on substrates using for removing the color of lignin concentration is interesting. The objectives of this research are to prepare the floating porous cylindrical tube substrates composed of zeolite NaA and ball clay, and then to determine the efficiency of lignin degradation. Zeolite NaA powder, Suratthani ball clay and organic binder solution were mixed before extruding and cutting to be 1.5 cm diameter cylindrical tube with 2.5 cm in length and 0.3 cm in thickness. After that, the dried tubes were fired at 650 - 800 °C for 2 hours and were then coated with TiO2-P25 suspension before re-firing at 600 °C for 1 hour in an electrical furnace. The fired uncoated tubes were characterized in terms of phase composition, porosity and radial crush strength. From the XRD pattern of the tubes fired at 800 °C showed that the zeolite NaA phase was disappeared. On the other hand, the zeolite NaA phase was found in the samples fired at another lower temperature. For the coated tubes, polyurethane foam was filled into the hole to make the tubes can be floated on the water surface. After that, the photocatalyst degradation property by determining the decreasing of concentration of lignin solution under tungsten lamp irradiation of the floated tubes were tested.