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Simulation-supported measurements in large circulating fluidized bed combustors

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Particuology 2009年第4期7卷 324-331页

作者： joachim Werther Ernst-Ulrich Hartge Lars Ratschow Reiner Wischnewski Institute of Solids Process Engineering and Particle Technology Hamburg University of TechnologyD 21071 HamburgGermany Now with Pyry Energy GmbH HamburgGermany Now with Hydro Aluminium AS OsloNorway

The concept of simulation-supported measurement is suggested for the elucidation of processes occurring in the combustion chambers of large-scale circulating fluidized bed combustors where the desired information cannot be obtained by direct measurements. The concept is illustrated with the example of secondary air injection where the way the air is released, the penetration depth and the evenness of air distribution over the cross-sectional area of the combustion chamber are of interest. The measured information consists of lateral profiles of oxygen concentrations measured with gas sampling probes at two ports which were located 5 and 9 m, respectively, above the level of secondary air injection. The simulation is carried out on the basis of a 3D semi-empirical fluid-mechanical model of the circulating fluidized bed which is combined with models of gas and solids mixing, fuel distribution, devolatilization and combustion of char and volatiles. The combination of the simulation with the measurements yields a clear picture of the mechanism of secondary air injection, its penetration into the combustion chamber and its effect on the local combustion processes. The results confirm the usefulness of the concept of simulation-supported measurement for this application.

关键词： Fluidized bed Combustion Local measurements 3D modeling

The ultimate goal of modeling—Simulation of system and plant performance

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Particuology 2011年第4期9卷 320-329页

作者： joachim Werther Stefan Heinrich Maksym Dosta Ernst-Ulrich Hartge Institute of Solids Process Engineering and Particle Technology Hamburg University of Technology

Modern production processes in chemical, pharmaceutical and biological industries are characterized by complex process structures, which consist of different apparatuses and process steps. Modeling the entire process requires simulating all units altogether, while taking into account interconnections between them, Nevertheless, in the area of solids processing, there is nowadays an unfilled gap from the side of computer support of process modeling in allowing effective optimization and prediction of the behavior of the whole plant, This paper presents a tool for flowsheet simulation which allows the simulation of the stationary behavior of complex processes dealing with solids and its extension towards dynamic modeling, Also, a new simulation concept is proposed on the basis of the multiscale approach. On the macroscale, fiowsheet simulation is performed with the help of the SolidSim system. Parameters for the macromodels in Solid-Sim are predicted by microscale simulation. The models for the two scales are then coupled by inter-scale communication laws. Application of the proposed modeling concept is shown by an example of fluidized bed granulation.

关键词： Flowsheet simulation Multiscale modeling Plant performance Solids processes Granulation

CFD-simulation of a circulating fluidized bed riser

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Particuology 2009年第4期7卷 283-296页

作者： Ernst-Ulrich Hartge Lars Ratschow Reiner Wischnewski joachim Werther Hamburg-University of Technology Institute of Solids Process Engineering and Particle TechnologyD-21071 HamburgGermany

In the current work, a model of the fluid mechanics in the riser of a circulating fluidized bed （CFB） has been implemented using computational fluid dynamics （CFD）. The model developed shall be used in future as the basis of 3D-reactor model for the simulation of large scale CFB combustors. The two-fluid model （TFM） approach is used to represent the fluid mechanics involved in the flow. The computational implementation is accomplished by the commercial software FLUENT. Different closure formulations are tested on a simplified geometry. Two different turbulence formulations, namely the swirl modified RNG k-e model and the Realizable k-e model, are tested in combination with two different approaches to solid phase turbulence, namely the dispersion and per phase approach. One focus of the current work is put on the study of different drag correlations. Besides the drag correlations by Syamlal et al. [Syamlal, M., Rogers, W., ＆ O＇Brien, T. J. （1993）. MFIX documentation theory guide. Technical Report DOE/METC-9411004, U.S. Department of Energy （DOE）. Morgantown Energy Technology Center： Morgantown, WV] and Gidaspow [Gidaspow, D. （1994）. Multiphaseflow andfluidization. New York： Academic Press] the EMMS model has been used to determine the momentum exchange between the two phases. The resulting formulation is then used to simulate a 1-m × 0.3-m cold CFB setup and is validated by experimental results [Schlichtharle, P. （2000）. Fluid dynamics and mixing of solids and gas in the bottom zone of circulating fluidized beds. Unoublished doctoral dissertation, Technische Universitaet Hamburg-Harburg, Shaker Verlag： Aachen].

关键词： Circulating fluidized bed Two-fuid model EMMS model Drag correlations

Biology and control of the fruit borer, Conopomorpha sinensis Bradley on litchi （Litchi chinensis Sonn.） in northern Thailand

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Insect Science 2007年第6期14卷 525-529页

作者： MARIE JOY SCHULTE KONRAD MARTIN joachim SAUERBORN Institute of Plant Production and Agroecology in the Tropics and Subtropics University of Hohenheim Stuttgart Germany

Fruit and leaf shoot of litchi （Litchi chinensis） infestation by naturally occurring populations of the fruit bprer, Conopomorpha sinensis larvae and C. sinensis parasitization rates were determined in litchi orchards in northern Thailand at high （ca. 1 400 m ASL） and low （ca. 800 m ASL） elevations with different, non-overlapping fruiting seasons. In addition, spray applications of Bacillus thuringiensis var. aizawai, the natural compound spinosad and the chemical pesticide imidacloprid were conducted in the field to test the effects of these agents on C. sinensis fruit infestation rate. Fruit infestation rate and fruit growth, studied in a low elevation orchard, were sigmoidal and showed a highly significant positive correlation （P ≤ 0.01）. Leaf shoot infestation rate in the low elevation orchard decreased in the course of the fruiting season （March until May）, but increased in the high elevation orchard, where no fruits were present within the same period of time. Together, these results indicate that females of C. sinensis clearly prefer fruits over shoots for oviposition. If no fruits are available, which was the case in the high elevation orchard during that time, they are constrained to lay their eggs on shoots. The parasitization rate of C. sinensis larvae in untreated fruits was 54.3%. The parasitoid species were Chelonus chailini （90.8%） and Phanerotoma sp. （9.2%）. In the leaf shoots, C. sinensis was found to be parasitized by Phanerotoma sp. and Apanteles briareus. The applications of the different active agents had no significant effect on C. sinensis fruit infestation compared to the untreated control. Besides the cryptic life of the larvae, this is most probably explained by the fact that C. sinensis has several generations during the fruiting season. Because of the high parasitization rates recorded, an alternative and more effective control measure than the application of pesticides might be the augmentative release of parasitoids.

关键词： Conopomorpha sinensis fruit infestation Litchi chinensis northern Thailand,parasitoids pest control

Deuterium retention in chemically vapor deposited tungsten carbide coatings and hot-rolled tungsten exposed to low-energy deuterium plasma

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Tungsten 2022年第1期4卷 10-19页

作者： Vladimir Kh.Alimov joachim Roth Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of SciencesMoscow 119071Russia Max-Planck-Institut fur Plasmaphysik 85748 GarchingGermany

Samples of chemically vapor deposited(CVD)coatings of tungsten carbides W_(45)C_(55)and W_(60)C_(40)and samples of hot-rolled tungsten were exposed to deuterium(D)plasma at sample temperatures ranging from 323 to 813 K,as a result of which the samples were irradiated with D ions with an energy of about 200 eV per D particle at a flux of D particles of about1.1×10^(21)D·m^(-2)·s^(-1)to a fluence of about 2×10^(24)D·m^(-2).The concentration of deuterium in these samples was examined by the D(3 He,p)4 He nuclear *** on the measured deuterium depth profiles and assuming that these profiles are determined by diffusing D atoms,the diffusion coefficients of deuterium in the CVD tungsten carbide coatings were *** these diffusion coefficients,an estimate of the Arrhenius relation for the diffusion coefficients of deuterium in CVD tungsten carbide coatings was obtained:D=2.5×10^(-3)exp(-1.12 eV/kT)m~2·s^(-1),where T is temperature expressed in Kelvin,and k is the Boltzmann *** concentration of trapped deuterium in the bulk of CVD tungsten carbide coatings is practically independent of the stoichiometry of the *** decreases from about 5×10^(-2)to about 7×10^(-4)D/(W+C)with an increase in the deuterium plasma exposure temperature from 373 to 813 *** concentration of trapped deuterium in hot-rolled tungsten,expressed in units of the D/W atomic ratio,is more than an order of magnitude lower than the concentration of deuterium in tungsten carbides,and also decreases with increasing plasma exposure temperature.

关键词： Chemically vapor deposited tungsten carbides Tungsten Deuterium plasma Deuterium depth profiles Deuterium diffusion coefficients

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

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Frontiers of Environmental Science & Engineering 2009年第2期3卷 226-235页

作者： Fangyue LI joachim BEHRENDT Knut WICHMANN Ralf OTTERPOHL Institute of Water Resources and Water Supply Hamburg University of TechnologySchwarzenbergstr.95 ED-21073 HamburgGermany Department of Wastewater Management Hamburg University of TechnologyEissendorfer Strasse 42D-21073 HamburgGermany

In this study,a mathematical model was established to predict the formation of the soluble microbial product(SMP)in a submerged membrane *** developed model was calibrated under the reference *** results were in good agreement with the measured results under the reference *** calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters:hydraulic retention time(HRT),dissolved oxygen concentration,and sludge retention time(SRT).Simulation results revealed that the SMP dominated the soluble organic substances in the *** scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality;dissolved oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality,reduce the content of SMP,and minimize operating costs;the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process,less membrane fouling potential,and acceptable organic removal efficiency.

关键词： hybrid activated sludge model(ASM) membrane bioreactor(MBR) soluble microbial product(SMP)

Electrochemically driven conversion reaction in fluoride electrodes for energy storage devices

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npj Computational Materials 2018年第1期4卷 462-476页

作者： Chilin Li Keyi Chen Xuejun Zhou joachim Maier State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai 200050China University of Chinese Academy of Sciences Beijing 100039China Max Planck Institute for Solid State Research Heisenbergstraße 1D-70569 StuttgartGermany

Exploring electrochemically driven conversion reactions for the development of novel energy storage materials is an important topic as they can deliver higher energy densities than current Li-ion battery ***-type fluorides promise particularly high energy densities by involving the light and small fluoride anion,and bond breaking can occur at relatively low Li activity(i.e.,high cell voltage).Cells based on such electrodes may become competitors to other envisaged alternatives such as Lisulfur or Li-air systems with their many unsolved thermodynamic and kinetic *** conversion reactions are typically multiphase redox reactions characterized by nucleation and growth processes along with pronounced interfacial and mass transport *** significant overpotentials and nonequilibrium reaction pathways are *** this review,we summarize recent findings in terms of phase evolution phenomena and mechanistic features of(oxy)fluorides at different redox stages during the conversion process,enabled by advanced characterization technologies and simulation *** can be concluded that well-designed nanostructured architectures are helpful in mitigating kinetic problems such as the usually pronounced voltage *** this context,doping and open-framework strategies are *** these tools,simple materials that are unable to allow for substantial Li nonstoichiometry(e.g.,by Li-insertable channels)may be turned into electroactive materials.

关键词： fluoride energy breaking

Direct Measurement of CO_2 Retention in Arable Soils with pH Above 6.5 During Barometric Process Separation Incubation

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Pedosphere 2018年第5期28卷 726-738页

作者： Hannah CONRADS joachim INGWERSEN JU Xiaotang Thilo STRECK Institute of Soil Science and Land Evaluation Biogeophysics SectionUniversity of Hohenheim College of Agricultural Resources and Environmental Sciences China Agricultural University

The barometric process separation(BaPS)technique is a well-established incubation method to simultaneously measure gross nitrification and respiration rates in *** application,however,is still critical in soils with pH above ***,a substantial part of microbial CO_2 production is retained in soil solution(CO_2,aq)due to shifts in the carbonate *** may lead to substantial errors in gas balance ***,utilization of the BaPS technique is only reliable if the critical term is adequately *** present an easy,inexpensive,and direct method,the sterilization-CO_2-injection(SCI)method,to measure CO_2 retention during soil *** soil was incubated in the BaPS system,and defined volumes of CO_2 were injected to stepwise increase CO_2partial pressure(p CO_2)inside the chamber and to analyse the physicochemical equilibration *** exemplary agricultural soils from Northeast China and Southwest Germany were used for method establishment,presenting pH values between 4.4 and 7.6 and carbonate contents between 0% and 3.9%.We observed that in soils with pH>6.5,70%–90% of the injected CO_2 was taken up by the soil until the equilibrium inside the chamber was *** expected,in soils with low pH(<6.5),measured CO_2 retention was ***_2 retention patterns were sensitive to incubation temperature with tri-fold dissolution capacity at 5~?C compared to 25?C,but insensitive to variations in soil water *** resulting soil-specific relationship between p CO_2 and CO_2,aq concentration allowed the quantification of CO_2,aq concentration as a function of headspace p CO_2.

关键词： carbonate equilibrium CO2 dissolution capacity CO_2 partial pressure microbial CO2 production soil pH sterilization-CO2-injection method volume of headspace air volume of soil solution

Verapamil and vasospastic angina： underuse in the elderly population

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Journal of Geriatric Cardiology 2017年第7期14卷 430-435页

作者： Xavier Humbert Vincent Roule Paul Milliez joachim Alexandre Department of General Medicine Medical School Caen France Department of Pharmacology CHU de Caen Caen France Normandie University UNICAEN CHU Caen Signalisation eleetrophysiologie et imagerie des lesions d'ischOmie-reperfusion myocardique Caen France Department of Cardiology CHU de Caen Caen France

The first case of Prinzmetal angina was described in 1959 by Prinzmetal, et al. Since this description, several triggering factors have been associated with vasospastic angina （VA） and included： illicit drugs such as cocaine, amphetamine or marijuana, but also bitter-orange, alcohol, butane, chemotherapy drugs, over-the-counter medication and different antibiotics. Smoking is also a major risk factor for developing VA.t21 Thus, except for smoking, many of conventional atherosclerosis risk factors do not appear to be applicable to VA.t21 However, vasospastic angina can also occur without any triggering factor.

关键词： Calcium antagonists Elderly population Prinzmetal angina Variant angina Verapamil