Bed Reactor (be + reactor)

Distribution by Scientific Domains

Kinds of Bed Reactor

  • Fluidize be reactor


  • Selected Abstracts


    Integrated Enzymatic Synthesis and Adsorption of Isomaltose in a Multiphase Fluidized Bed Reactor

    ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 5 2006
    M. Ergezinger
    Abstract Dextransucrase catalyzes the formation of dextran, but also of numerous oligosaccharides from sucrose and different acceptors, if appropriate conditions are chosen. A process on a technical scale with immobilized enzyme was established to produce isomaltose, a disaccharide of industrial interest. Isomaltose is also a reactant for dextransucrase and has to be quickly taken out of the reaction solution. This was realized by integrated adsorption of isomaltose on zeolites. In the case of biotransformation the reactor works with a fluidized bed of immobilized enzyme and the in situ separation is realized with a suspension flow of adsorbent. This process was investigated experimentally and theoretically. With a design model consisting of hydrodynamics, kinetics of enzymatic synthesis, and thermodynamics of adsorption, a comparison was made between experimental and calculated data. [source]


    Biofilm Growth and Bed Fluidization in a Fluidized Bed Reactor Packed with Support Materials of Low Density,

    ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2004
    R.A. Saucedo-Terán
    Abstract Support materials of low-density for fluidized bed reactors provide several operational advantages, including lower energy requirements and proper biofilm growth balance. The aim of this investigation was to study the extent of biofilm growth and bed fluidization in an experimental reactor, using polyester resin (,pr,=,1220,kg/m3) and vitrified expanded perlite (,vep,=,1710,kg/m3) as alternative support materials to conventional silica sand. A noteworthy amount of biofilm was observed to be attached to both support materials from the very beginning of the bioreactor operation. Nevertheless, there were significant variations in biofilm growth and activity over the course of the experimental trials. For both perlite and polyester beds, the highest biofilm mass and the highest total number of mesophilic bacteria were observed between the 7th and the 10th day, showing a steady state trend at the end of the experimental runs. The chemical oxygen demand (COD) removal levels were concomitant with biofilm mass and total mesophilic bacteria changes, although the polyester bed efficiency was slightly higher than that for the perlite bed. As expected, the polyester bed was fluidized at a lower re-circulation flow compared to the perlite bed. Reactor back-washing was not required for these support materials since biomass excess was adequately separated by means of a special internal device. The efficiencies of removal of organic matter achieved were acceptable (up to 78,%) despite the low volume of the support material (25,%) and the low hydraulic retention time (30,min). [source]


    Combined Treatment of Perchlorate and RDX in Ground Water Using a Fluidized Bed Reactor

    GROUND WATER MONITORING & REMEDIATION, Issue 3 2007
    Mark E. Fuller
    A bench-scale study was conducted to assess the effectiveness of biological treatment of comingled perchlorate and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in ground water using fluidized bed reactors (FBRs). In addition, the ability of FBRs to treat low concentrations of perchlorate was examined. Pilot-scale FBRs were fed either acetic acid or molasses as an electron donor to facilitate simultaneous perchlorate and RDX reduction. The acetic acid-fed FBR consistently removed perchlorate from an influent level of 100 ,g/L to below 6 ,g/L, and values below the method detection limit of 1 ,g/L occurred approximately 70% of the time. RDX breakthrough from all FBRs was minimal due to sorption of the explosive on the granulated activated carbon media, but mass balance calculations indicated that more than 99.5% of the total RDX entering the acetic acid-fed FBR was biologically degraded. Approximately 80% of the RDX fed to the control FBR (i.e., no substrate addition) was accounted for at the end of the study; the remainder was assumed to have been degraded. Molasses was much less effective than acetic acid as an electron donor for treatment of perchlorate and RDX. This work demonstrates that combined treatment of perchlorate and RDX is feasible using FBR technology, and that very low levels of perchlorate (less than 100 ,g/L) can be effectively treated in an FBR. [source]


    Atomic Layer Deposition of UV-Absorbing ZnO Films on SiO2 and TiO2 Nanoparticles Using a Fluidized Bed Reactor,

    ADVANCED FUNCTIONAL MATERIALS, Issue 4 2008
    David M. King
    Atomic layer deposition (ALD) was used to apply conformal, nanothick ZnO coatings on particle substrates using a fluidized bed reactor. Diethylzinc (DEZ) and water were used as precursors at 177,°C. Observed growth rates were ca. 2.0 Å/cycle on primary particles as verified by HRTEM. ICP-AES and XPS were used to quantify Zn:substrate ratios. Layers of 6, 18, and 30 nm were deposited on 550 nm SiO2 spheres for UV blocking cosmetics particles. TiO2 nanoparticles were coated in the second part of this work by ZnO shells of 2, 5, and 10 nm thickness as novel inorganic sunscreen particles. The specific surface area of powders changed appropriately after nanothick film deposition using optimized conditions, signifying that high SA particles can be functionalized without agglomeration. The ZnO layers were polycrystalline as deposited and narrowing of the FWHM occurred upon annealing. Annealing the ZnO-TiO2 nanocomposite powder to 600,°C caused the formation of zinc titanate (Zn2TiO4) in both oxygen-rich and oxygen-deficient environments. The non-ideal surface behavior of the DEZ precursor became problematic for the much longer times required for high surface area nanoparticle processing and results in Zn-rich films at this growth temperature. In situ mass spectrometry provides process control capability to functionalize bulk quantities of nano- and ultrafine particles without significant precursor waste or process overruns. ZnO overlayers can be efficiently deposited on the surfaces of primary particles using ALD processing in a scalable fluidized bed reactor. [source]


    Xylitol Production from Sugarcane Bagasse Hydrolyzate in Fluidized Bed Reactor.

    BIOTECHNOLOGY PROGRESS, Issue 4 2003
    Effect of Air Flowrate
    Cells of Candida guilliermondiiimmobilized onto porous glass spheres were cultured batchwise in a fluidized bed bioreactor for xylitol production from sugarcane bagasse hemicellulose hydrolyzate. An aeration rate of only 25 mL/min ensured minimum yields of xylose consumption (0.60) and biomass production (0.14 gDM/gXyl), as well as maximum xylitol yield (0.54 gXyt/gXyl) and ratio of immobilized to total cells (0.83). These results suggest that cell metabolism, although slow because of oxygen limitation, was mainly addressed to xylitol production. A progressive increase in the aeration rate up to 140 mL/min accelerated both xylose consumption (from 0.36 to 0.78 gXyl/L·h) and xylitol formation (from 0.19 to 0.28 gXyt/L·h) but caused the fraction of immobilized to total cells and the xylitol yield to decrease up to 0.22 and 0.36 gXyt/gXyl, respectively. The highest xylitol concentration (17.0 gXyt/L) was obtained at 70 mL/min, but the specific xylitol productivity and the xylitol yield were 43% and 22% lower than the corresponding values obtained at the lowest air flowrate, respectively. The concentrations of consumed substrates and formed products were used in material balances to evaluate the xylose fractions consumed by C. guilliermondii for xylitol production, complete oxidation through the hexose monophosphate shunt, and cell growth. The experimental data collected at variable oxygen level allowed estimating a P/O ratio of 1.35 molATP/molO and overall ATP requirements for biomass growth and maintenance of 3.4 molATP/C-molDM. [source]


    Oxidation of Benzene to Maleic Anhydride in a Fluidized Bed Reactor

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 12 2007
    C. Uraz
    Abstract In this project, the selective oxidation of benzene to maleic anhydride (MAN) was studied. Gas phase catalytic oxidation of benzene was carried out in a laboratory scale fluidized bed reactor on six different types of catalysts, which have different compositions. Effects of temperature, flow rates of benzene and air and catalyst type on the reaction selectivity were investigated at atmospheric pressure. The experiments were performed over a temperature range of 325 to 400,°C, a space-time (W/FA0) range from 11.28,×,105 to 31.9,×,105 g,s,mol,1, and benzene/air mole ratio changes between 0.0109 and 0.0477. It was seen that conversion of benzene to MAN increased with increasing temperature for the catalysts supported by silica gel, aluminum oxide and titanium oxide. From the results it was found that conversion increased with increasing flow rate of air. When the comparison of the catalysts were made, it could be said that catalysts supported by silica gel showed higher MAN conversions. So it can be concluded that catalysts supported by silica gel were more suitable catalysts for benzene oxidation to MAN in a fluidized bed reactor. [source]


    Some Issues on Core-Annulus and Cluster Models of Circulating Fluidized Bed Reactors

    THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2002
    Hsiaotao T. BiArticle first published online: 19 MAY 200
    Abstract The one-dimensional cluster model and the core-annulus model are examined based on existing correlations. The core-annulus model is found to give reasonable agreement with ozone decomposition data when the effective interphase mass transfer rate constant is equal to about 0.1 1/s, which is one order smaller than the reported values based on gas tracer tests. The prediction from the core-annulus model that the reactor performance decreases with increasing the riser diameter is found to be inconsistent with limited experimental data The one-dimensional cluster model predicts that a riser reactor performs very close to the pseudo-homogeneous plug flow reactor because of the high mass transfer rate between the cluster and the dilute phase. The improvement of model predictions lies in the better characterization of the cluster shape, size and the mass transfer rate between the cluster and the dilute phases. Le modèle de grappes unidimensionnel et le modèle c,ur-espace annulaire sont examinés d'après des corrélations existantes. On a trouvé que le modèle c,ur-espace annulaire décrivait raisonnablement bien les données de décomposition de l'ozone lorsque la constante de taux de transfert de matière entre phases réelle est égale à environ 0,1 s-1, ce qui est d'un ordre de grandeur plus petit que les valeurs obtenues d'après des tests par gaz traceurs. La prédiction du modèle c,ur-espace annulaire selon laquelle la performance du réacteur diminue avec l'augmentation du diamètre de la colonne montante s'avère non cohérente avec les quelques données expérimentales. Le modèle de grappes unidimensionnel prédit que la performance d'un réacteur à colonne montante est très proche de celle d'un réacteur à écoulement piston pseudo-homogène du fait du taux de transfert de matière élevé entre la grappe et la phase diluée. L'amélioration des prédictions du modèle repose sur une meilleure caractérisation de la forme des grappes, de leur taille et du taux de transfert de matière entre les grappes et les phases diluées. [source]