Methanation in a fluidized bed reactor with high initial CO partial pressure: Part I—Experimental investigation of hydrodynamics, mass transfer effects, and carbon deposition

An extensive experimental study on the methanation reaction was carried out in a gas–solid fluidized bed reactor at 320 °C with a stoichiometric ratio of H₂/CO=3. By means of spatially resolved measurements of the axial gas species concentration and temperatures along the fluid bed the effects of different catalyst loadings, gas velocities and dilution rates were observed and analyzed. By applying this technique, it was found that most of the reaction (CO and H₂ conversion) proceeds in the first 20 mm of the bed depending on the experimental conditions. For a few cases, the temperature increases by up to 80 °C from 320 to 400 °C within the first 3 mm of the bed. By increasing the inlet volume flow only by a factor of 1.4, the temperature hotspot diminishes and isothermal behavior develops. For all experiments, a CO conversion of practically 100% was achieved. The experimental data indicate that the dense phase of the fluidized bed is probed and that mass transfer between bubble and dense phase is dominating in the upper part of the bed. It could be shown that both hydrodynamic and chemical boundary conditions influence the methanation reaction inside the fluidized bed reactor.     

Fieldbus-internet connectivity: the SNMP approach

Important reasons for connecting fieldbus systems to IP-based networks are the provision of remote access for monitoring and maintenance purposes, but also the inclusion of automation systems into an enterprise-wide management scope. Existing solutions are chiefly based on Web technology or require specialized, fieldbus-dependent tools. In this paper, the authors propose a different strategy using the standardized and widely used Simple Network Management Protocol. This approach is largely fieldbus-independent and, at the same time, interoperable with existing LAN technology. They discuss the architecture of a protocol conversion gateway and present a modular approach to cope with the variety of available fieldbus protocols. They further propose a structure for a management information base suitable to represent the fieldbus data objects. By means of prototype implementations for different fieldbus systems (Profibus, P-NET, and EIB), they study the influence of the underlying fieldbus communication principles on the gateway implementation and operation     

The impact of sulfur on the performance of a solid oxide fuel cell (SOFC) system operated with hydrocarboneous fuel gas

The impact of thiophene in the fuel gas of a commercial solid oxide fuel cell (SOFC) system is investigated for concentrations up to 400 ppmV. Based on the measured voltage–current curves, an empiric correlation for the estimation of the expectable power output of the investigated SOFC system when operated with sulfur containing fuel gases is derived. An interrelation between the open circuit voltage (OCV) and the sulfur concentration of the investigated hydrocarboneous fuel gas is presented and discussed based on corresponding model simulations. The reduction of the steam reforming (STR) activity of the anode cermet material and of the catalytic partial oxidation catalyst used for the fuel gas processing in the investigated SOFC system are found important factors regarding the power output reduction induced by sulfur traces in the fuel gas of SOFCs.     

纽马格推动客户BCF生产

地毯和地毯纱市场总是充满着挑战,新的需求不断地出现。地毯业的时尚潮流在快速地变化着,同时全球性的压力也在稳步增长。地毯业在这样的竞争环境中必须找到能够保持成功的途径。在这种情况下．工艺链前期的BCF技术对地毯纱和地毯生产是否成功起着决定性的作用。     

High-Temperature Proton Conductors for the Injection of Hydrogen into a Vacuum

Tubes of ceramic high-temperature proton conductors (CaZr_0.9In_0.1O_{3− x} ,BaZr_0.9Y_0.1O_{3− x} , and Ba₃Ca_1.18Nb_1.82O_{9− x} )were used to introduce hydrogen into a vacuum system. A prerequisite was a leak rate below 10⁻⁸mbar/s for an assembly consisting of the active tube and a 8YSZ support tube. Mass spectrometry showed that the partial pressure of hydrogen in the vacuum system, p _H2, increased linearly with the electric current flowing through the proton conductor. All other important partial pressures remained unaffected by this operation. Calculation of throughput during operation of the hydrogen source essentially revealed that the total current, J , is used to transport protons from the anode to the cathode ( t _H∼ 1). The number of moles of H₂ transported per second is given by J /2 F . In essence, the present proton conductor tube constitutes a precise, current-controllable device, with a response time of a few seconds only, that delivers ultrahigh-purity hydrogen to a vacuum system.     

Scalable Functionalization of Optical Fibers Using Atomically Thin Semiconductors

Atomically thin transition metal dichalcogenides are highly promising for integrated optoelectronic and photonic systems due to their exciton-driven linear and nonlinear interactions with light. Integrating them into optical fibers yields novel opportunities in optical communication, remote sensing, and all-fiber optoelectronics. However, the scalable and reproducible deposition of high-quality monolayers on optical fibers is a challenge. Here, the chemical vapor deposition of monolayer MoS₂ and WS₂ crystals on the core of microstructured exposed-core optical fibers and their interaction with the fibers’ guided modes are reported. Two distinct application possibilities of 2D-functionalized waveguides to exemplify their potential are demonstrated. First, the excitonic 2D material photoluminescence is simultaneously excited and collected with the fiber modes, opening a novel route to remote sensing. Then it is shown that third-harmonic generation is modified by the highly localized nonlinear polarization of the monolayers, yielding a new avenue to tailor nonlinear optical processes in fibers. It is anticipated that the results may lead to significant advances in optical-fiber-based technologies.     

Short communication: Activity of nisin,lipid bilayer fragments and cationic nisin-lipid nanoparticles against multidrug-resistant Staphylococcus spp. isolated from bovine mastitis

Staphylococci are the main etiological agents of bovine mastitis. Bacteriocins and nanoparticles have emerged as promising alternatives for the future development of antimicrobial agents. This study evaluated the activity of the bacteriocin nisin and bicelles of the synthetic cationic lipid dioctadecyldimethylammonium bromide, alone and in combination, against multidrug-resistant Staphylococcus spp. strains isolated from bovine mastitis. In summary, cationic nisin/dioctadecyldimethylammonium bromide nanoparticles are shown to be a promising alternative for the control of mastitis caused by multidrug-resistant Staphylococcus spp.