Modeling and Experimental Analysis of PSD Measurements through FBRM

Abstract

The Focused Beam Reflectance Measurement (FBRM) technique provides on‐line and in‐situ information about the chord length distribution of a population of particles in dispersion. This is rather promising for applications such as crystal size distribution control in crystallization processes. The objective of this study is to deepen the understanding of the characteristics of the FBRM measurement. On the one hand, a model is presented, which allows in principle to transform particle size distributions (PSD) into chord length distributions (CLD). On the other hand, measurements with particles in suspension show the critical dependence of the measurement on the optical properties of the system. A special technique has been developed to measure CLDs of single particles. These measurements clarify some of the above effects, detect possible over‐ and underestimations of particle size and give indications about how to interpret and exploit on‐line CLD spectra.

Optimal seed recipe design for crystal size distribution control for batch cooling crystallisation processes

“…Seeding seems to be treated as an art rather than science (Adi et al, 2007;Jagadesh et al, 1999;Kalbasenka et al, 2007;Kubota et al, 2001;Ludwick and Henderson, 1968;Lung-Somarriba et al, 2004) and generally there is a lack of systematic methodologies related to the amount and size of seeds that should be added into a crystallizer to obtain a product with a desired size distribution. Although it is recognized that the most important manipulated variables for the optimisation of crystallisation processes are supersaturation trajectories as well as the seed characteristics (Bohlin and Rasmuson, 1996;Heffels and Kind, 1999;Kalbasenka et al, 2007;Ruf et al, 2000, Yannick et al, 2009, the number of approaches focusing on temperature or anti-solvent addition trajectory optimisations is disproportionally higher than contributions considering seed recipe optimisations. The approaches proposed so far, mainly consider the optimisation of the width and amount of a particular monomodal seed distribution (Chung et al, 1999;Kalbasenka et al, 2007).…”

Sparsity-based image monitoring of crystal size distribution during crystallization

“…With the rapid development of process analytical technology (PAT) in the past decade [2], a few real-time measurement methods have been explored for measuring CSD based on using the laser diffraction (LD), ultrasound attenuation (UA), and focused beam reflectance measurement (FBRM) technologies [3,4]. In particular, FBRM has been increasingly applied for on-line monitoring of crystal size distribution termed as cord length distribution [5,6], which is mainly effective for spherical particles.…”

Transformation of CSD When Crystal Shape Changes with Crystal Size into CLD from FBRM by Using Monte Carlo Analysis

“…FBRM (focused beam reflectance measurement) can measure CLD (chord length distribution) in line, but it is well known that CLD is different from CSD because of principle of FBRM [2] [3]. In FBRM, focused beam from probe enters suspension in vessel, and chord length is measured based on detection time of backscattered light when beam runs cylindrically at high speed.…”

“…In some of previous studies [2] [3], discretizing was used to solve complex integral problems. In this paper, by using Monte Carlo analysis instead of discretization, the transforming matrix can be calculated quickly and accurately.…”

“…In this paper, by using Monte Carlo analysis instead of discretization, the transforming matrix can be calculated quickly and accurately. Translation, which is one of the variables defining chord length, was made to exist within variable range and weighting was performed for each range in many of previous studies [2] [3]. In this paper, translation is made to exist within fixed sufficient range in order to avoid weightings in CLD calculation process.…”