ISSN:
0934-0866
Keywords:
Chemistry
;
Industrial Chemistry and Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
A method has been developed to increase the sensitivity of phase Doppler interferometry-based particle sizing systems to small particles in the presence of a spray containing large and small droplets; an important consideration when using seed particles to track the gas-phase velocity in multi-phase flows. The method, applicable to PDPA systems configured to operate in first and higher order refraction mode, involves doping the sprayed liquid with a dye that is strongly absorbing at the incident laser wavelengths. This results in greatly diminished scattered intensity from larger droplets, thus allowing the photomultiplier gain to be set to a level sufficient to easily detect small particles without saturation. Tests conducted indicate that, at a collection angle of 30° and droplet absorptivity of γ = 0.014/μm, the PDPA can accurately size absorbing droplets up to approximately 200 μm. This upper limit can be extended by changing selection angle. Tests performed with an actual spray demonstrated that the method allowed detection of 1 μm to 235 μm droplets; more than four times the instrument's usual range of 50: 1. A data correction scheme to determine the effective probe volume radius for each particle size class has been developed for absorbing particles, as standard correction schemes derived for non-absorbing droplets excessively weigh distributions toward smaller particles.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ppsc.19950120504
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