SBIR-STTR Award

The feasibility of using a novel light scattering intensity ratiotechnique for the simultaneous measurements of the speed and sizeof non-spherical particles will be examined in Phase I. Thetechnique makes use of two concentric laser beams with differentdiameters and the amplitude of the signals from the lightscattered by the particles traveling through the probe volume toinfer their size and speed. The sizing of irregular particles isaccomplished by using near forward collection of the scatteredlight, in which depolarization of the scattered light byirregular particles is not significant, and the scattered lightintensity is only sensitive to the projected area of theparticles. The planned technique will have the ability to (1)size both spherical and non-spherical particles, (2) measure theparticle number density and volume flux, and (3) measure theparticle speed. The objectives of Phase I are to: (1) investigatethe feasibility of using this novel technique for nonsphericalparticle size measurements, (2) conduct calibration measurementsof spherical and nonspherical particles, and (3) study thefeasibility of using laser diode technologies for compact probedevelopment.Anticipated Results /Potential Commercial Applications as described by the awardee: The planned laser diagnostic techniquefor particle sizing has a wide range of applications in practicalenvironments. It can be used for the diagnostics of spherical andnon-spherical particles present in flue gas streams, coal-waterslurries, soot conglomerates, fly ash, and combustion generatedparticles. There is presently no single instrument which cansuccessfully be used for measuring particles in such a wide rangeof industrial applications.

As environmental awareness continues to grow, so does the need for more robust environmental monitoring instruments, including fine particle sizing instruments. Over the years, the study of fine particulate pollution has been relatively neglected compared with chemical pollutants such as ozone and sulfur dioxide. Particulates less than 10 microns are among the most dangerous atmospheric pollutants and are hazardous to human health. These fine particles include dust, soot, smoke, or tiny droplets of acid. The removal of contaminants, including particulates, from hot gas streams is also essential for the successful development of advanced coal utilization and conversion processes. Therefore, there is a need for the development of non-intrusive diagnostic instruments that can be used for on-line monitoring of particulate emission. In Phase I, the feasibility of using a coaxial laser beam arrangement for the accurate measurement of individual, non-spherical particles was demonstrated. A novel ratioing scheme was implemented to eliminate sizing errors that result from the Gaussian nature of the incident laser beams. The optical, electro-optical, and signal processing considerations for measuring particles in the size range 0.3 to 100 microns was addressed. This size range represents a signal dynamic range of almost 108 which is an engineering challenge. In Phase II, a prototype ratiometric particle sizer will be developed and tested.Anticipated Results/Potential Commercial Applications as described by the awardee:The planned laser diagnostic technique for particle sizing has a wide range of practical applications. It can be used for the diagnostics of spherical and non-spherical particles present in flue gas streams, coal-water slurries, soot conglomerates, fly ash, and combustion generated particles. The success of this instrument will be very beneficial to the Nation and will allow the commercial sector to adhere to the stringent regulations of the Clean Air Act.