Long-term CO2 capture tests of Pd-based composite membranes with module configuration

In this study, we investigate the configuration of a Pd–Au composite membrane on a porous nickel support and membrane modules for withstanding the capture of CO₂ from a coal gasifier for a long time. The hydrogen permeation flux, recovery and CO₂ capture were experimentally evaluated using two different modules and two conditions. As in our study, the CO₂ capturing and durability tests were performed with a 40% CO₂/60% H₂ feed gas mixture in stainless steel (SS) 316L and 310S membrane modules. As a result, it is achieved the durability tests for more than 1150, 1100 (SS 316L module) and 3150 h (SS 310S module) with pressure cycles from 100 to 2000 kPa at 673 K. The durability of the membranes and membrane modules was demonstrated under pressure cycles from 100 to 2000 kPa at 673 K and the SS 310S module was very stable after 3150 h. The durability test for more than 3000 h demonstrated that there was no significant intermetallic diffusion between the PNS and Pd–Au layer. The CO₂ capturing test performed using a 40% CO₂/60% H₂ mixture confirmed that the CO₂ capturing capacity of the membrane and membrane module was 2.0 L/min for a CO₂ concentration in the retentate stream of 92.3% and that the hydrogen recovery ratio increased with increasing pressure and reached 93.4%. Furthermore, we suggest that the SS 310S module configuration, CO₂ capturing test using Pd–Au/ZrO₂/PNS membrane and membrane module is very suitable for application as an Integrated Gasification Combined Cycle (IGCC) system due to very simple numbering-up stackable module design was successful.     

Improvement of hydrogen-sorption characteristics of Mg by reactive mechanical grinding with prepared by spray conversion

Nano-structured Cr₂O₃ powder could be produced by spray conversion (spray drying of an aqueous of Cr nitrate, oxidation and milling).The samples Mg—10 wt% Cr₂O₃ using nano-structured Cr₂O₃ synthesized by spray conversion were prepared by mechanical grinding under H₂ (reactive mechanical grinding) under the optimum conditions, previously studied, for the preparation of the sample Mg—10 wt% Fe₂O₃ using purchased Fe₂O₃. The sample Mg—10 wt% Cr₂O₃ as milled absorbed 4.48 wt% H₂ at 593 K under 12 bar H₂ for 60 min. Its activation was accomplished after two hydriding–dehydriding cycles. The activated sample absorbed 5.48 wt% H₂ for 10 min and 5.93 wt% H₂ for 60 min at 593 K, 12 bar H₂, and desorbed 3.65 wt% H₂ at 603 K, 1.0 bar H₂ for 60 min. H₂-storage capacity was 6.38 wt% under 12 bar H₂ at 593 K (from P–C-T curve). Reactive mechanical grinding of Mg with Cr₂O₃ by spray conversion increased the hydriding rate effectively but increased a little the dehydriding rate, compared with reactive mechanical grinding of Mg with Fe₂O₃ purchased, Fe₂O₃ by spray conversion, MnO and SiO₂ by spray conversion.     

Laminar fluid flow in a twisted elliptic tube

Twisted tubes are important in generating secondary flow and fluid mixing in a cross-stream direction. In the present paper, the fully developed laminar fluid flow through twisted elliptic tubes is numerically analyzed up to a large twist ratio by using the finite difference method. The elliptic solution domain is transformed to a rectangular computational domain by using a new, simple, and analytic transformation containing a removable singularity. The effect of the two parameters, the tube twist ratio and the aspect ratio of the ellipse, is investigated with respect to their role in determining the axial and circumferential velocities, the streamline patterns, and the resistance coefficients.     

Economic evaluations of direct, indirect and hybrid coal liquefaction

The various geopolitical problems associated with oil have rekindled interest in coal, with many countries working on projects for its liquefaction. This study established the feasibility of coal liquefaction through a technical and economic examination of direct coal liquefaction (DCL), indirect coal liquefaction (ICL) and hybrid coal liquefaction (HCL) processes. An economic efficiency analysis was prepared involving costs of initial investment, annual operating and raw coal purchase and revenues from the sale of major products as key variables. For the raw materials, products and investments, analyses of net present value (NPV), internal rate of return (IRR) and sensitivity were carried out. The processes?? IRRs were found to be 22.26% (DCL), 18.43% (ICL) and 20.90% (HCL). NPVs were $4.720m (DCL), $3.811 m (ICL) and $4.254 m (HCL), and payback periods were DCL 3.3 years, ICL 4.2 years, and HCL 3.6 years. As a result of the sensitivity analysis, factors greatly affecting the earning potential of coal liquefaction included product prices, raw coal prices, and construction costs, which showed similar effects in each process.     

Synthesis gas and char production from Mongolian coals in the continuous devolatilization process

Devolatilization of Mongolian coal (Baganuur coal (BC), Shievee Ovoo coal (SOC), and Shievee Ovoo dried coal (SOC-D)) was investigated by using bench-sized fixed-bed and rotary kiln-type reactors. Devolatilization was assessed by comparing the coal’s type and dry basis, temperature, gaseous flux, tar formation/generation, devolatilization rate, char yield, heating value, and the components of the raw coal and char. In the fixed bed reactor, higher temperatures increased the rate of devolatilization but decreased char production. BC showed higher rates of devolatilization and char yields than SOC or SOC-D. Each coal showed inversely proportional devolatilization and char yields, though the relation was not maintained between the different coal samples because of their different contents of inherent moisture, ash, fixed carbon, and volatile matter. Higher temperatures led to the formation of less tar, though with more diverse components that had higher boiling points. The coal gas produced from all three samples contained more hydrogen and less carbon dioxide at higher temperatures. Cracking by multiple functional groups, steam gasification of char or volatiles, and reforming of light hydrocarbon gas increased with increasing temperature, resulting in more hydrogen. The water gas shift (WGS) reaction decreased with increasing temperature, reducing the concentration of carbon dioxide. BC and SOC, with retained inherent moisture, produced substantially higher amounts of hydrogen at high temperature, indicating that hydrogen production occurred under high-temperature steam. The continuous supply of steam from coal in the rotary kiln reactor allowed further exploration of coal gas production. Coal gas mainly comprising syngas was generated at 700–800 °C under a steam atmosphere, with production greatest at 800 °C. These results suggest that clean char and high value-added syngas can be produced simultaneously through the devolatilization of coal at lower temperature at atmospheric pressure than the entrained-bed type gasification temperature of 1,300–1,600 °C.     

Effects of fruiting body extracts of Lentinus edodes cultivated using corn cob on biological activities

We investigated the antioxidant, nitrite scavenging, immune-enhancing and antimicrobial effects of the Lentinus edodes fruiting body extracts (LEFB extract) cultivated in the solid state using corn cob. The CAT, SOD and GSH-Px activities in the LEFB extract (400mg)-fed group were approximately 1.70, 1.64, and 2.2 times higher than those of the control group. The nitrite scavenging activity was highest (86.4%) when the LEFB extract concentration was 600 μg/mL. The immune-enhancing and antimicrobial effects of LEFB extract after an experimental Bordetella bronchiseptica infection were examined. White blood and neutrophil in the LEFB extract (400 mg)-fed group were approximately 2.1 and 2.2 times higher, respectively, than those of the control group. The total leukocyte was 30% higher than that of the control group. The CD4: CD8 ratio in the LEFB extract (200 mg)-fed group was increased approximately 54.3% compared to that of the control group. The levels of TNF-α and IFN-γ mRNA expression in the LEFB extract (400 mg)-fed group were approximately 49 and 50% lower than those of the control group. The bacteria and inflammatory cell in the LEFB extract (400 mg)-fed group were approximately 48.7 and 29% lower, respectively, than that of the control group. These results suggest that the LEFB extract may be useful in immune function improvement.