Beam Reflectance Measurement (beam + reflectance_measurement)

Distribution by Scientific Domains

Kinds of Beam Reflectance Measurement

  • focused beam reflectance measurement


  • Selected Abstracts


    Restoration of PSD from Chord Length Distribution Data using the Method of Projections onto Convex Sets

    PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 2 2005
    Jörg Worlitschek
    Abstract The interpretation of chord length distributions (CLDs) is essential in many fields and has been discussed by various authors. Here, the technique of the Focused Beam Reflectance Measurement (FBRM) is considered as on-line and in-situ measurement device of the CLD of particle dispersions and emulsions. Though useful in general, this measurement cannot be converted directly into a particle size distribution (PSD), unless the physics of the measurement method is described and accounted for. In this work we present a new tool to carry out such a conversion once the particle shape is known a priori and can be fixed, which is based on a two step procedure: (1) the computation of a matrix that converts the PSD of a population of particles with given shape into the corresponding CLD using a 3-dimensional geometric model; (2) the calculation of the PSD from the resulting linear matrix equation for the measured CLD. Here, the method of Projections onto Convex Sets (POCS) is applied to solve the PSD restoration problem, which is a mathematically ill-posed inverse problem. We study the effect of particle shape and matrix dimension on the ill-posed character of the inverse problem. A detailed error analysis of the CLD allows for a predictive description of a posteriori constraints in the POCS framework. We discuss the application of this method to the characterization of simulated test cases and experimentally obtained data. [source]


    Flocculation Monitoring: Focused Beam Reflectance Measurement as a Measurement Tool

    THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2002
    A Blanco
    Abstract A methodology to study flocculation processes and floc properties using a non-imaging scanning laser microscope is presented in this paper. This methodology allows us to study floc stability and resistance to shear forces, re-flocculation tendency and reversibility of the flocs. Furthermore, optimal dosage of any polymer and the associated flocculation mechanism can be determined. In order to illustrate the technique, some examples applied to flocculation in papermaking are described. Although in this paper all the examples have been applied to papermaking, the developed methodology can be used in any process in which flocculation phenomena is involved. On présente dans cet article une méthode pour étudier les procédés de floculation à l'aide d'un microscope laser à balayage sans imagerie. Cette méthode permet d'étudier la stabilité des flocs et leur résistance aux contraintes de cisaillement, la tendance à la refloculation et la réversibilité des flocs. De plus, on peut déterminer le dosage optimal de tout polymère et le mécanisme de floculation associé. Pour illustrer cette technique, quelques exemples appliqués à la floculation dans la fabrication du papier sont décrits. Cependant, même si dans cet article tous les exemples s'appliquent à la fabrication du papier, la méthodologie peut s'appliquer à tout procédé comportant des phénomènes de floculation. [source]


    Online Measurement of Hydrocortisone Particles and Improvement of the Crystallization Process

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 7 2009
    J.-X. Chen
    Abstract Many methods have been developed to measure crystal particle size. The online Focused Beam Reflectance Measurement (FBRM) and a classical offline Laser Diffraction Method (LDM) were used to measure the size of the polyvinylchloride (PVC) particles and hydrocortisone (HC) crystals. For the standard spherical PVC particles, the particle sizes measured using both FBRM and LDM are similar. However, for the anomalistic HC particles, the difference between the particle sizes measured by the above two methods increased with the increase in the degree of scrambling. The online monitoring of the particle size by direct installation of a FBRM probe into the crystallization process helped indicate the crystal quality, and thus, improve the control of crystallization processes. [source]


    Utilization of Focused Beam Reflectance Measurement in the Control of Crystal Size Distribution in a Batch Cooled Crystallizer

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2006
    S. Barthe
    Abstract Controlling crystal size distribution (CSD) is important to downstream processing and to product quality. The distribution can be characterized by a mean or dominant size and the spread about the mean or dominant size. The development of tools leading to the control of the distribution in a batch crystallizer is the main topic of the present study. An experimentally based control scheme was implemented for batch cooling crystallization of paracetamol from ethanol solutions. Estimates of the CSD in the batch crystallizer were obtained by applying a model of the octahedral paracetamol crystals to a chord length distribution (CLD) obtained from focused beam reflectance measurement (FBRM) and Lasentec software. The model estimates showed reasonably good agreement with results obtained from sieve analyses performed at the end of the runs. [source]


    Principal component analysis for estimating population density from chord-length density

    AICHE JOURNAL, Issue 9 2009
    Martha A. Grover
    Abstract The relationship between crystal population density and chord-length density (CLD) is complicated and depends on the size and shape of the crystals. Although estimation of chord-length density from the population density is relatively straightforward, the inversion of this procedure is problematic because the problem may be ill-conditioned for nonspherical particles. The focus of this work is on this inversion process. Since the relationship is a function of the crystal geometry, this manuscript considers various nonspherical shapes, including highly challenging needles. We describe an efficient method to estimate the population density from a measured CLD, to analyze the inversion process, and to quantify its limits. Since noise is present in the actual Focused Beam Reflectance Measurements, the case of restoration of the population density from noisy CLDs also is demonstrated. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source]


    Influence of Cationic Starch Adsorption on Fiber Flocculation

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2009
    N. Zakraj
    Abstract The adsorption of cationic starch on hardwood fibers and its influence on flocculation were studied in relation to the dosage of cationic starch, the effect of shear forces and the presence of different concentrations of inorganic salts in the paper stock. Flocculation was monitored by means of a focused beam reflectance measurement (FBRM) probe. It was established that floc size at low shear rates depends on adsorption efficiency. At high shear forces, flocs were irreversibly decomposed despite the presence of a higher amount of adsorbed cationic starch on the fibers. Therefore, flocculation was produced by a bridging mechanism. The results show a significant effect of inorganic salts on the adsorption of cationic starch on fibers. Low concentrations of inorganic salts usually improved the adsorption process while higher concentrations (> 0.01 mol/L) reduced the adsorption and limited the flocculation process. [source]


    Utilization of Focused Beam Reflectance Measurement in the Control of Crystal Size Distribution in a Batch Cooled Crystallizer

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2006
    S. Barthe
    Abstract Controlling crystal size distribution (CSD) is important to downstream processing and to product quality. The distribution can be characterized by a mean or dominant size and the spread about the mean or dominant size. The development of tools leading to the control of the distribution in a batch crystallizer is the main topic of the present study. An experimentally based control scheme was implemented for batch cooling crystallization of paracetamol from ethanol solutions. Estimates of the CSD in the batch crystallizer were obtained by applying a model of the octahedral paracetamol crystals to a chord length distribution (CLD) obtained from focused beam reflectance measurement (FBRM) and Lasentec software. The model estimates showed reasonably good agreement with results obtained from sieve analyses performed at the end of the runs. [source]