Alfa Laval (Sweden)

The interconnects in a SOFC or SOEC stack are subject to a high temperature environment with air or O2 on one side and a H2/H2O mixture on the other. This so-called dual atmosphere is known to result in corrosion that differs from the results obtained in experiments where the steel is exposed to only one of these atmospheres. In SOFC context a dual atmosphere effect was first reported by Yang et al. in 2003 [1]. They reported that AISI 430 exposed to dual atmosphere conditions (air // H2-3%H2O) formed a more Fe rich oxide scale, including the presence of Fe2O3, on the air side while a reference experiment with air on both sides resulted in a protective oxide scale of Cr2O3 and spinel. This triggered a stream of investigations studying various FSS under dual atmosphere conditions. Most of these studies focused on temperatures of 800-900°C (relevant operating temperatures for SOFCs at that time) and gave contradictory results. Some authors confirmed Yangs findings [2] or found an even more severe effect [3]while others reported only a slight enrichment of Fe in the oxide scale or no observable effect at all [4–7]. Nevertheless, there is agreement that the dual atmosphere effect is only observed on the air side and the fuel side is unaffected of whether the other side of the sample is exposed to air or H2/H2O. Subsequent work by Alnegren et al. [8] and Gunduz et al [9] investigated AISI 441 under dual atmosphere conditions at temperatures between 500-800°C. These studies showed the most severe dual atmosphere effect was observed at 600°C and that higher temperatures, somewhat counterintuitive, resulted in more protective oxide scales. The apparent contradictions in the results have led some authors to attribute the dual atmosphere effect to leakages or sealant contamination and questioned its practical relevance [10]. This work revisits these earlier studies to discuss factors that might explain the discrepancies observed and allows for a reinterpretation of the previous findings.Figure 1 shows the piping made of 316L stainless steel leading towards the dual atmosphere sample holder after the first experiment at 600°C (temperature of the pictured section was <600°C). While the steel pipe with air on the inside shows a thin protective scale its counterpart that was filled with Ar-5%H2 is massively corroded on the air side. Similar results with tubular specimens of AISI 316L were published by Holcomb et al [11]. Hence, there is an abundance of studies confirming the existence of a dual atmosphere effect. It is also commonly agreed upon that hydrogen diffuses through the metal affecting air side oxidation. Nevertheless, the underlying mechanism of how hydrogen affects the air side oxidation is elusive. In this contribution the merits of different proposed mechanisms will be discussed. Finally, mitigation strategies to prevent dual atmosphere corrosion will be reviewed.

El 3-monocloropropano-1,2-diol (3-MCPD) es un contaminante en aceites vegetales que se forma a temperaturas elevadas durante el procesamiento y se considera nocivo para la salud. El cloro presente en el aceite de palma crudo (APC) actúa como precursor en la síntesis de 3-MCPD, lo que hace crucial su control para garantizar la seguridad alimentaria. Este articulo evalúa la eficiencia de una tecnología de lavado diseñada para reducir la concentración de cloro en el APC, con el propósito de alcanzar el límite comercial recomendado de 2,0 mg/kg. Se realizó un caso de estudio en una planta de beneficio que implementa esta tecnología, para lo cual se midieron los niveles de cloro en diversas etapas del proceso, desde la entrada hasta la salida, y en muestras específicas de los tanques de despacho. Los resultados obtenidos demuestran una reducción significativa del cloro en el aceite tratado, lo que confirma la eficacia del sistema de lavado. Específicamente, se observó que el cloro total en las muestras de salida del sistema de lavado se mantuvo consistentemente por debajo del límite establecido, con valores que oscilaron entre 0,6 y 0,7 mg/kg con una eficiencia del 75 % al 96 %. Este estudio destaca la importancia de contar con otra tecnología disponible para el sector palmero, como lo es el lavado de aceite, para garantizar la calidad del APC y mitigar la formación de compuestos indeseables como el 2- y 3-MCPD. De esta manera, se contribuye a la producción de un aceite con mejor calidad.

A systematic four-stage methodology was developed and applied to the Laser Metal Deposition with Wire (LMDw) of a duplex stainless steel (DSS) cylinder > 20 kg. In the four stages, single-bead passes, a single-bead wall, a block, and finally a cylinder were produced. This stepwise approach allowed the development of LMDw process parameters and control systems while the volume of deposited material and the geometrical complexity of components increased. The as-deposited microstructure was inhomogeneous and repetitive, consisting of highly ferritic regions with nitrides and regions with high fractions of austenite. However, there were no cracks or lack of fusion defects; there were only some small pores, and strength and toughness were comparable to those of the corresponding steel grade. A heat treatment for 1 h at 1100 °C was performed to homogenize the microstructure, remove nitrides, and balance the ferrite and austenite fractions compensating for nitrogen loss occurring during LMDw. The heat treatment increased toughness and ductility and decreased strength, but these still matched steel properties. It was concluded that implementing a systematic methodology with a stepwise increase in the deposited volume and geometrical complexity is a cost-effective way of developing additive manufacturing procedures for the production of significantly sized metallic components.

Removal of the native surface oxide from steel is an important initial step during vacuum brazing. Trace and alloying elements in steel, such as Mn, Si, and Ni, can diffuse to the surface and influence the deoxidation process. The detailed surface chemical composition and grain morphology of the common stainless‐steel grade 316L is imaged and spectroscopically analyzed at several stages of in‐vacuum annealing from room temperature up to 850°C. Measurements are performed using synchrotron‐based X‐ray photoemission and low‐energy electron microscopy (XPEEM/LEEM). The initial native Cr surface oxide is amorphous and unaffected by the underlying Fe grain morphology. After annealing to ~700°C, the grain morphology is seen at the surface, persisting also after the complete oxygen removal at 850°C. The surface concentration of first Mn and then Si increases significantly when annealing to 500°C and 700°C, respectively, while Ni and Cr concentrations do not change. Mn and Si are not located only in grain boundaries or clusters but are distributed across over the surface. Both Mn and Si appear as oxides, while Cr oxide becomes metallic Cr. Annealing from 500°C up to 850°C leads to the removal of first the Mn and then Si oxides from the surface, while Cr and Fe are completely reduced to metals. Deoxidation of Cr occurs faster at the grain boundaries, and the final Cr metal surface content varies between the grains. The findings are summarized in a general qualitative model, relevant for austenite steels.

Nanocellulose is known to act as a platform for the in-situ formation of metal oxide nanoparticles, where the multiple components of the resultant hybrids act synergistically toward specific applications. However, typical mineralization reactions require hydrothermal conditions or addition of further reducing agents. Herein, we demonstrate that carboxylated cellulose nanofibril-based films can spontaneously grow functional metal oxide nanoparticles during the adsorption of heavy metal ions from water, without the need of any further chemicals or temperature. Despite the apparent universality of this behavior with different metal ions, this work focuses on studying the in-situ formation of copper oxide nanoparticles on TOCNF films as well as the resultant hybrid films with improved functionality toward dye removal from water and antimicrobial activity. Using a combination of cutting-edge techniques (e.g., in-situ SAXS and QCMD) to systematically follow the nanoparticle formation on the nanocellulosic films in real time, we suggest a plausible mechanism of assembly. Our results confirm that carboxylated cellulose nanofibril films act as universal substrate for the formation of metal oxide nanoparticles, and thus hybrid nanomaterials, during metal ion adsorption processes. This phenomenon enables the upcycling of nanocellulosic materials through multistage applications, thus increasing its sustainability and efficiency in terms of an optimal use of resources.

A sharp reduction of the energy consumption of a high‐speed centrifuge was obtained following several design changes, while still maintaining separation capacity. This reduction is necessary for making some applications commercially interesting, e.g., large‐volume flow rates in the growing biopharma industry. The reduction was achieved by modifying flow paths of the rotor, i.e., reducing the outlet radius to minimize angular momentum losses and lowering the pressure drop of the internal flow. Further, removing air outside the rotor reduced aerodynamic losses, and using a direct drive motor, losses encountered with gear or belt drives were eliminated. This way, an average energy reduction of 50 % was obtained.

Rheological characterization of the solids phase in bio‐industry disc‐stack centrifuges is considered. Three discriminatory properties of the solids phase are investigated, namely, the particle settling velocity, the angle of repose, and the solids phase viscosity. The solids phase produced in disc‐stack centrifuges in the food or biopharmaceutical industry possesses both liquid‐like and solid‐like properties which can be quantified by means of these test methods. The resulting rheological characterization can be used for diagnostic purposes in the selection process of industrial centrifuges and for optimization of centrifuge solids handling in biomass processing of suspension systems.

This chapter presents a unique system approach applied in a joint academic–industrial research programme, E4 Mistra, to attain the goals of high energy efficiency and low emissions in an exhaust aftertreatment system for heavy-duty vehicles. The high energy efficiency is achieved by heat recuperation, onboard hydrogen production for NO x reduction, and by finding new solutions for making the aftertreatment system active at low exhaust temperatures. To reach low particulate emissions, a mechanical filter using a sintered metal powder is developed and coated with catalytic material to improve the soot oxidation efficiency. Low NO x emissions are achieved by an efficient NO x reduction catalyst.

Abstract The article contains sections titled:1.Introduction2.Fundamentals2.1.Centrifugal Sedimentation2.2.Centrifugal Sedimentation with Continuous Flow3.Centrifugal Separators with Continuous Feed3.1.General3.2.Disk‐Bowl Machines3.3.Chamber and Multichamber Bowls3.4.Tubular Bowl Centrifuges3.5.Decanter Centrifuges3.6.Other Bowl Geometries4.Batch Centrifuges4.1.General4.2.Bottle Centrifuges4.3.Batch Zonal Centrifuges5.Fluid Dynamics in Centrifuges5.1.Chamber and Tubular Bowl Centrifuges5.2.Disk‐Bowl Centrifuges5.3.Decanter Centrifuges6.Centrifuge Technology6.1.Rotor Dynamics6.2.Materials Selection7.Centrifuge Selection7.1.Introduction7.2.Main Process Parameters7.3.Test Tube Centrifugation (Spin Test)7.4.Important Properties of the Process Streams7.5.Improvement of Separability7.6.Pilot Machine Testing7.7.Scale‐Up8.Applications