Instrumental particle sizer

An optical microscope, a standard set of sieves, an Andreasen Pipette, and any versatile instrumental particle sizer, such as a laser diffraction equipment or an electrical sensing zone particle counter. 

Determine the particle size distribuhon of feed using an instrumental particle sizer. 

A related technique that is suitable for measurement of aerosols at lower mass loadings is the aerodynamic particle sizer (3, 10). In this instrument the aerosol is rapidly accelerated through a small nozzle. Because of their inertia, particles of different aerodynamic sizes are accelerated to different velocities, and the smallest particles reach the highest speeds. The particle velocity is measured at the outlet of the nozzle. From the measurements of velocities of individual particles, particle size distributions can be determined. The instrument provides excellent size resolution for particles larger than about 0.8 xm in diameter, although sampling difficulties limit its usefulness above 10 xm. 

The most often measured property of the LRT wildfire smokes is the mass concentration of aerosol particles in fine (PM2.5) or submicron (PMi) or in fine and coarse size fraction together (PM10). The mass concentration is usually determined either with a tapered element oscillating microbalance (e.g., [19]), or with the instruments based on p-attenuation (e.g., [13]). In addition to mass concentration, real-time instruments can measure other physical properties of particles, e.g., number concentration of particles in different size fractions using a differential mobility particle sizer [13] or the optical characteristics of smoke by a nephelometer [32]. Ground-based instruments also include remote sensing instruments such as sun photometers [32],... 

For the micron size range an optical on-line particle sizer was used, working on the principle of white light scattering on single particles. This instrument provided number concentration and size distribution measurements in the range 0.3-30 pm, with a maximum of allowed particle number concentration of 10 particles/cm. ... 

Next, the sampling flow was guided to different measurement instruments. The concentration number and the size distribution of submicron particles (0.01-0.5 pm) was obtained with a TSI Scanning Mobility Particle Sizer (SMPS) consisting of a differential electrical mobility analyzer coupled with a condensation nuclei counter. Previously a preconditioning gas system was used. This basically consists of a cyclon,... 

Instruments using the residence time, such as the aerodynamic particle sizers, or the particle velocity, as used by the phase Doppler particle analyzers, measure the particle size primarily based on the aerodynamic diameter. 

Figure 18 Principle of operation of a Fraunhofer diffraction laser particle sizer. (With permission of Malvern Instruments, Inc.)...

Another time-of-flight instrument, the Aerodynamic particle sizer (APS), is manufactured by TSI Incorporated (St. Paul, Minnesota). This system operates at subsonic flow conditions and cannot tolerate as high a flux of particles as the AeroSizer. As of 1996, the development of time-of-flight instruments is ongoing. 

For a spherical particle of nonunit density the classical aerodynamic diameter is different from its physical diameter and it depends on its density. Aerosol instruments like the cascade impactor and aerodynamic particle sizer measure the classical aerodynamic diameter of atmospheric particles, which is in general different from the physical diameter of the particles even if they are spherical. 

Quasi-elastic light scattering (QELS) experiments were conducted on both neutralized and unneutralized sols, in a Brookhaven model BI-90 particle sizer. This instrument measured the autocorrelation function, C(t), and fit this function to... 

Colloid growth under different conditions was monitored using photon correlation spectroscopy, which measures the size of submicron particles. The size of colloid particles during the growdi process was measured with 90 Plus Particle Sizer (Brookhaven Instrument Co., Holtsville, NY). The reactions were conducted inside the cuvettes supplied with the instrument The experiments were run imder conditions listed in Table n. Measurements were made automatically by the instruments at pre-set times. KCl was added to the reaction solution to provide the same ionic strength for all runs. 

Here, C is a constant and dy the volume equivalent diameter. Since 4n can be measured with instruments such as a differential mobility analyser (DMA) or scanning mobility particle sizer (SMPS) and dy can be estimated as a function of N (for a given d ) as described above, then Equation (9.3) can be used to estimate a fractal dimension based on the mass-mobility relationship with known values of Jp and N. The fractal dimension may be obtained from Equation (9.2) as the slope of log(Mp) versus log(fi ni)-An alternative method for estimating Df (for values of 2 or larger) can be derived using the results of Rogak et al. [57] and Schmidt-Ott [50]. For Df > 2.0 ... 

Liposome Size Measurements. Sizes were determined at 25°C by quasielastic light scattering (QELS) with a fixed 90 scattering angle using a Brookhaven Instrument Corporation Particle Sizer Model BI-90 equipped with a He/Ne laser. In a typical measurement values were determined over 2000 cycles with a count rate of 50 kpcs. The software provided by... 

Christianson Scientific Equipment supply the Fritsch Analysette 22 laser particle sizer which operates over the particle size range 0.16-1250 pm. This is a universally applicable instrument for determining particle size distributions of all kinds of solids which can be analysed either in suspension in a measuring cell or dry by feeding through a solid particle feeder. In the Fritsch Analysette 22, laser diffraction apparatus the measured particle size distribution is displayed on the monitor in various forms, either as a frequency distribution or as a summary curve in tabular form, and can be subsequently recorded on a plotter, stored on hard disk, or transferred to a central computer via an interface. The time required for one measurement is approximately two minutes. 

Heidenreich and co-workers, have investigated the calibration of an optical stream particle counter using the Aerodynamic Particle Sizer manufactured by TSI Instruments Inc which will be described in the next section [46]. 

Fig ure 6.16. Schematic diagram of the inspection zone of the Amherst Process Instruments Inc. Aerosizer dme-of-flight particle sizer. 

Another aerosol spectrometer is manufactured by TSI Incorporated. Their instrument is known as the Aerodynamic Particle Sizer (APS). This system operates at subsonic flow conditions, and has a lower rate of count than the Aerosizer . The performance of the instrument has been documented in various publications [59, 60, 61]. In... 

Setekleiv and Svendsen [180] used the same laser difliraction particle sizer to characterize the ability of mesh pads to separate droplets from the gas stream in a scrubber. Droplets in the size range 30-1000 p,m with a bi-modal distribution was obtained at low pressure. A rough sketch of the mounting of the laser diffraction instrument used in this work is shown in Fig. 13.17. Numerous applications of the LD particle sizer for solid particle size distribution measurements characterizing aerosols and suspensions can be found in the literature. Only a few examples of laser diffraction solid particle size distribution measurements relevant for fluidized bed system characterization are mentioned in this report. Garea et al. [71] measured the solid sorbent particle size distribution in a fluidized bed in-duct desulfurization reactor under in-duct conditions by laser diffraction. Ferrer et al. [66] studied fluidized bed combustion of refuse-derived fuel in presence of protective coal ash and measured the fly ash particle size distribution with a laser diffraction method. Tanneur et al. [192] measured the solid particle size distribution in a fluidized bed by use of a diffraction particle size analyzer. 

In a couple of particular papers, the application of LD particle sizer to measure the size distribution of micro-bubbles are mentioned. Couto et al. [44] performed micro-bubble size distribution measurements by the laser diffraction technique. It was concluded that the size distribution of micro-bubbles generated for the dissolved air flotation process could be assessed on a fast and reliable way by the application of the laser diffraction technique. The micro-bubble size distribution was measured by the Mastersizer 2000 SM equipment from Malvern Instruments, UK. The instrument specifications state that analysis in the particle range from 0.1 to 2000 ttm is possible, and the data interpretation computations could either be performed by use of the... 

The particle diameters were determined by dynamic light scattering (Brookhaven Instruments, Model BI-90 particle sizer) and molecular weights, by GPC (Waters Styragel columns, THF as eluent, PMMA samples as standards). 

---