Numerical Simulation of Fluidized Bed Gasifier Coupled with Solid Oxide Fuel Cell Fed with Solid Carbon

A model of a fluidized bed coupled with direct carbon solid oxide fuel cell (SOFC) is developed to explore the effect of coupling between fluidized bed and solid oxide fuel cell. Three gas–solid flow regimes are involved including fixed bed, delayed bubbling bed and bubbling bed. The anode reaction of SOFC is treated as the coupling processes of Boudouard gasification of carbon and electrochemical oxidation of CO. The effects of inlet velocity of the fluidizing agent CO2, carbon activity, channel width and coupling extent on the system performance are investigated. The results show that the inlet velocity of CO2 can promote the gasification rate in the anode, but too high velocities may lower CO molar fraction. The gasification rate generally increases with the increase of the channel width and carbon activity. The overlapping area between the anode surface and the initial carbon bed, gas–solid regime and carbon activity have a significant influence on the gasification rate and the maximum current density the system can support. Overall, the mass transport in the anode is dramatically enhanced by the expansion of the carbon bed, back-mixing, solid mixing and gas mixing, especially for the delayed bubbling bed and bubbling bed. This indicates that the adopted coupling method is feasible to improve the anode performance of direct carbon solid oxide fuel cell.

Two BSHS online alternatives to conventional conferences

In 2020, the BSHS hosted two major online events, the first of their kind in our collective experience. The first, a Twitter conference, was planned and accomplished before COVID-19 had quite been established as a serious global issue. The conference was planned, rather, as an innovation in travel-free conferencing, something that has been on the BSHS agenda since the IPCC report of 2018, calling for net-zero-carbon activity in all areas by 2050. As we discussed the Twitter conference, and watched the amazing energy, intellect and resourcefulness of its planners and hosts, we quickly saw that online delivery offered other advantages too – chiefly, wider participation. The pandemic offered the society a chance to take these lessons very boldly into the most important event of our scholarly calendar, which usually takes the form of an in-person annual conference, but this time was executed as an online festival.

Atypical Cases of Welded Structure Failures

First case describes hot temperature corrosion of 1.4841 heat resisting steel, which was caused by formation of the low melting nickel sulphide (LME effect).In the second case centrifugally cast tubes of Ø52.6 x 5.8 mm size made of 25/35 CrNi steel, which are exposed to high temperature and to severe reducing environment (carbon activity ac >> 1), are concerned. In such condition a graphitization may start, that results in the disintegration of its structure, which is called ,,metal dusting”.The third case is dealing with an attack of the 1.4301 steel pipe welds by microbiologically influenced corrosion. After short service time several leakages of water were revealed. It was proved, that failure was caused by microbiologically influenced corrosion of sulphate-reducing bacteria (SRB) and not by an improper welding technology.

Phase Equilibrium in Carbothermal Reduction Al2O3 → AlN Studied by Thermodynamic Calculations

As a ceramic with high economic value, aluminum nitride possesses high thermal conductivity, excellent electrical insulation, high mechanical strength and high melting temperature and these all are required in high technologies involving cooling, insulation, thermal expansion and corrosion. This paper deals with thermodynamic parameters which affect the Al2O3→AlN reduction efficiency during a carbothermal reduction. According to the carbothermal reduction reaction γ-Al2O3 + 3C + N2 → AlN + 3CO, if molar mixing ratio of γ-Al2O3:C = 1:3 at 1,601 °C or higher, the γ-Al2O3 can be reduced to AlN. This carbothermal reduction reaction is controlled by main parameters of carbon activity, and partial pressures of nitrogen, carbon monoxide and carbon dioxide. For example, if less carbon is added, a lower carbothermal reduction rate is resulted; however, if extra carbon is added, aluminum carbide (Al4C3) could be produced, or C could remain in AlN. Without N2(g) added in the carbothermal reduction, Al2O3(γ) may react with C to generate Al4C3 at a temperature higher than 2,250 °C. AlN prefers to form with an unity carbon activity, at a lower oxygen partial pressure, a higher carbon monoxide partial pressure, or at a higher temperature. In order to understand the relationship with N2, O2, CO, CO2, C, Al2O3, AlN and Al4C3, the Al-N-C-O system was investigated by thermodynamic calculations.