Showing papers on "Particle-size distribution published in 1982"

Aerosol Technology : Properties, Behavior, and Measurement of Airborne Particles

Abstract: Properties of Gases Uniform Particle Motion Particle Size Statistics Straight-Line Acceleration and Curvilinear Particle Motion Adhesion of Particles Brownian Motion and Diffusion Thermal and Radiometric Forces Filtration Sampling and Measurement of Concentration Respiratory Deposition Coagulation Condensation and Evaporation Atmospheric Aerosols Electrical Properties Optical Properties Bulk Motion of Aerosols Dust Explosions Bioaerosols Microscopic Measurement of Particle Size Production of Test Aerosols Appendices Index

Size Distribution of Fine Particles from Coal Combustion

Abstract: Measurements of the particle size distribution at the outlets of six coal-fired utility boilers showed a peak at a particle diameter near 0.1 micrometer. This submicrometer mode appears to be a general feature of coal combustion that results from a volatilization-condensation process in the boiler. At the boilers tested, the submicrometer mode contained 0.2 to 2.2 percent of the total fly ash mass. The importance of this mode is greater than its small quantity suggests because particles in the submicrometer size range are often much more difficult to collect with conventional particulate control devices than larger particles. Thus, the submicrometer mode may significantly influence the design and selection of future power plant emission controls. The particle mass in the submicrometer mode was correlated with the nitric oxide concentration in the flue gas. This correlation suggests that control of nitric oxide by modification of the combustion conditions may reduce the generation and emission of submicrometer particles.

Correlation of Maximum Dry Density and Grain Size

Abstract: A predictive relationship between the maximum dry density and the grain size distribution curve for noncohesive soils has been formulated. A parametric expression has been derived and the parameters have been evaluated by fitting experimental values for 43 soil samples. The results of this evaluation have indicated that the maximum dry density of a noncohesive soil can be estimated with a reasonable degree of accuracy if the grain size distribution of the soil is known.

Comparative size distribution measurements on chain aggregates

Abstract: Size distribution measurements of polydisperse iron oxide chain aggregates (600–1300 A thick with aspect ratios up to 700) were made and compared, using an aerosol centrifuge, a cascade impactor, and an electrical aerosol analyzer, with supporting data from electron microscopy. Number and volume frequency distributions are compared and analyzed on the basis of means and widths only. Appropriate conversions between aerodynamic and mobility equivalent diameters are made. Preferred particle orientation due to flow field and electrostatic field is taken into account. An estimate for the increase of average charge per fiber over that of spheres is given for the EAA's diffusion charger.

Measurement of size and size distribution of particles by fluidization.

Abstract: A method of particle size distribution measurement using a fluidization curve is developed. The size distributions observed in binary and the tertiary mixtures were in agreement with those by microscopic measurement. For those mixtures the apparent minimum fluidizing velocity, if the particles were completely segregated, us, determined by Us=(ΣWi/Woumfi)-1where Wi/Wo is the weight fraction corresponding to umfi. The values calculated from the above expression were in good agreement with the experimental data. The main disadvantage of this method is that, in the fluidization bed, the terminal velocity of the minimum-diameter particle must be less than the fluidizing velocity of the maximumdiameter particle, and the measurable size ratio (xmax/xmin) is 8-10.

Granules with a narrow particle size distribution comprising filler, crystalline polyolefin powder and binder

Abstract: Granules containing 60 wt. % or more filler, having such particle size distribution that 90 wt. % or more granular particles have a particle size of (1/3)d50 b to 3d50 b (d50 b : mean particle size of the granules), and being produced by blending (a) 60 to 90 parts by weight of a filler having a mean particle size of 0.05 to 100μ, (b) 5 to 35 parts by weight of crystalline polyolefin powder having a mean particle size (d50 a) of 150 to 1,000μ and having such particle size distribution that 90 wt. % or more particles thereof have a particle size of (1/2)d50 a to 2d50 a, (c) 5 to 35 parts by weight of a binder having a melting point lower than that of said crystalline polyolefin powder by a least 10°C., and optionally, (d) a compounding additive, at a temperature lower than the melting point of the crystalline polyolefin powder and higher than the melting point of the binder, is disclosed.

Photographic sensitive silver halide material

Abstract: PURPOSE:To obtain a sensitive material with high sensitivity and superior grainness while reducing the amount of used silver by forming a silver halide emulsion layer consisting of >=2 kinds of singly dispersed emulsions each having a specified particle size distribution on a support CONSTITUTION:A silver halide emulsion layer is formed on a support by applying 2-5 kinds of different singly dispersed emulsions each contg silver halide particles having 02-30mum average particle size so that the particle size distribution curve of the silver halide particles has 2-5 peaks when the emulsions are mixed, the difference is particle size between the mode of the maximum peak and the mode of the 2nd peak is regulated to >=3mum, and the number of silver halide particles each having a smaller particle size than the middle value of the average particle size of all the constituent particles is made larger than the number of silver halide particles each having a larger particle size than the middle value

The Motion of Particles Inside a Droplet

Abstract: Equations of motion for particles translating inside a droplet with internal circulation were developed. The forces experienced by these particles and their relative importance are also summarized. Sample calculations for coal particles in oil droplets show that for high-droplet Reynolds numbers, particles will accumulate near the droplet surface before substantial evaporation of the droplet, based on the results that the characteristic time of transport is two orders of magnitude smaller than the droplet lifetime. These accumulations of particles near the droplet surface will probably result in particle agglomeration. Fow low-droplet Reynolds numbers the particles are making slow looping motions and the characteristic time of transport is comparable to the droplet lifetime. This results in a more even distribution of particles in the droplet with slightly higher particle density near the surface. This indicates a higher particle burning rate and the possibility of internal boiling and microexplosion due to heterogenous nucleation initiated from those coal particles.

Process for making titanium, zirconium and hafnium-based metal particles for powder metallurgy

Abstract: A process to produce passified Group IVb transition metal based metal particles having a controlled particle size distribution is disclosed which produces particles suitable for metallurgy usage without additional particle size reduction. Such particles are also substantially free of halides and are produced at temperatures considerably below that of arc melting temperatures of Group IVb transition metals and alloys based thereon.

Refractory mould body and method of casting using the mould body

Abstract: A refractory mould core for producing metallic castings of complicated internal shape formed from a water-soluble salt having the following particle size distribution: 100% by weight of the particles have a size less than 750 μm; 90% by weight of the particles have a size of 8-600 μm; 80% by weight of the particles have a size of 5.5-500 μm; 70% by weight of the particles have a size of 4-400 μm; 60% by weight of the particles have a size of 2.8-350 μm; 50% by weight of the particles have a size of 2.0-280 μm; 40% by weight of the particles have a size of 1.6-220 μm; 30% by weight of the particles have a size of 1.0-180 μm; 20% by weight of the particles have a size of 0.3-160 μm; 10% by weight of the particles have a size of 0.1-125 μm.

Some Aspects of Seeding Flames with Refractory Oxide Particles

Abstract: An experiment has been conducted to determine the variation in light scattering characteristics of refractory oxide particles (TiO2 and AI2O3) as they pass through a laminar pre-mixed hydrogen-air flame. It was found that AI2O3 was not affected by the flame but Ti02 particles exhibited a substantial reduction in scattered light intensities. In addition the effect of agglomeration on particle light scattering measurements of the fluctuating concentration field in a turbulent flame was evaluated with the use of Mie scattering computations. The broadness of the initial particle size distribution was found 1o be a dominant parameter. Measurements using nearly monodisperse aerosols were most sensitive to agglomeration

Measurement of particle size and refractive index using crossed-beam laser anemometry

Abstract: The light scattered by spherical particles crossing the test space of a laser fringe anemometer is monitored simultaneously at two angles. From the visibilities of the signals the particle size distribution and one component of the refractive index may be determined. For non-absorbing particles this is the complete refractive index. Measurements were made on a water spray, glass ballotini and titanium and aluminium oxide particles in flames. Spherical metal oxide particles were produced by the combustion of metal powder in an oxygen-rich methane flame. Extension to the measurement of the full complex refractive index is discussed.

Production of macrospherical particles

Abstract: A process and improved apparatus are provided for producing macrospherical particles. The particles themselves have increased wall thicknesses and higher densities than particles produced by conventional means and are thus not subject to deep lung penetration. The produced particles are also of controlled (narrow) particle size distribution. Such particles are particularly well adapted for use as anti-perspirants. The process for producing the particles comprises providing a solution containing the materials from which the particles are made, dispersing the solution along a plurality of radially disposed bristles by centrifugal force into discrete liquid droplets and drying the solution droplets in a stream of heated air. The improved apparatus comprises mounting a rotatable atomizer having a plurality of bristles inside a spray drying chamber.

Particle generation, transport, and characterization at the First International Workshop on light absorption by aerosol particles

Abstract: Aerosol particles with a wide range of light absorption properties were generated, transported, and characterized to permit meaningful intercomparisons of all the major types of light absorption instruments. The particles were generated in concentrations of ~1 mg m−3 and 50 μg m−3 for periods up to 2 h. The particle characteristics ranged from highly absorbing carbonaceous to nearly transparent ammonium sulfate, from submicron ammonium sulfate to supermicron Arizona road dust, and from spherical ammonium sulfate to chain-aggregate carbonaceous and irregular ambient particles.

A study on the measurement of particle size distribution with laser diffraction systems

Abstract: The measurement of particle size distribution using a superimposed Fraunhofer diffraction pattern of moving particles on the focal plane was investigated. The following results were obtained. (1) Analysing the obscuration of diffracted light intensity of slits by obstacles behind the slits, the influence of particle numbers in a unit volume (cm3) on the diffracted light intensity was estimated. (2) At the mean particle size 60μm, it is found that this system can measure the correct particle size distribution for the particle numbers<6 × 104 in a unit volume (cm3).

An inventory of particles from stratospheric collectors - Extraterrestrial and otherwise

Abstract: Examination of 526 particles in the 2-50 micron size range obtained from stratospheric impaction collectors has shown that most of them fit into one of three groups on a simple plot of Mg/Si versus Al/Si energy dispersive X ray peak ratios. The particles within a given group exhibit strong correlations in composition and mineralogy to one another, and the groups appear to largely consist either of earth crustal, manmade, or extraterrestrial materials. The temporal variability and relatively flat size distribution of material in the earth crustal group, in particular, suggests an aircraft-related, as opposed to stratospheric, source for these particles.

Heat resistant porous film

Abstract: PURPOSE: To improve the corrosion resistance of a film by forming a sintered film of aluminum oxide having specific average pore sizes on the surface of a porous material produced from heat resistant oxide by an ordinary method. CONSTITUTION: Alumina powder having 0.3W10μm average particle size is formed to a required shape and is calcined whereby a heat resistant porous material having 1,500W5,000Å fine pore size is obtd. A slurry consisting essentially of α- alumina of the grain size distribution wherein the average diameter of crystal particles is in a 150W3,000Å range and the particles are packed densely is coated on the surface thereof and is dried by heating to 30W150°C, whereafter the porous material is calcined at 900W1,300°C to form a thin film of alumina having 1W20μm thickness. The film is joined securely with the substrate and has high permeability for gas. The film is used as a diaphragm for separation of gaseous hydrogen to be used in a corrosive atmosphere. COPYRIGHT: (C)1983,JPO&Japio

Coal slurry composition

Abstract: A coal-water slurry comprises: (a) a coal powder of which 71 to 85 percent by weight are coal particles of particle sizes of 74 mu or smaller, and which, moreover, has a particle size distribution such that, when said distribution is represented on a Rosin-Rammler chart, the gradient (in terms of the value of tan alpha ) of the straight line joining two points respectively corresponding to the quantity (percent by weight) of particles of particle sizes less than 44 mu and to the quantity (percent by weight) of particles of particle sizes less than 74 mu is 0.4 to 0.9; (b) at least one species of a specific surfactant; and (c) water.

Process for the desulfurisation of flue gases

Abstract: In this process for dry flue gas desulphurisation, reagents (calcium carbonate, magnesium carbonate, calcium oxide, magnesium oxide, etc.) of a grain size distribution are used, whose maximum is either at larger or at substantially smaller grain diameters than the maximum of the fly ash leaving the vessel (Figures 1 and 2). By selecting suitable separation equipment, this fly ash/reagents mixture is separated in such a way that a mass flow predominantly containing fly ash and a mass flow predominantly containing reagents are formed. The mass flow predominantly containing reagents can be taken to an industrial use or, in order to increase the utilisation of the reagents employed, be recycled to the furnace. If the maximum of the grain size distribution of the reagents employed is at a larger grain diameter than the maximum of the grain size distribution of the fly ash, it is advantageous to grind the mass flow which predominantly contains reagents, before it is re-used, and thus to obtain a substantially smaller grain size distribution. This process variant was illustrated in Figure 4. It is to be noted here that the unburned matter which is found in the fly ash in the case of the large grain diameters of the grain size distribution, is appropriately recycled to the combustion.

A new particle size distribution

Abstract: A new particle size distribution with inbuilt desirable properties has been defined Eleven sets of data chosen from the literature show that the new distribution can represent a mixture of sizes of particles excellently well Equations have been derived to estimate the specific surface area of a powder sample where the new distribution refers to number, length, area, and volume (or weight) distribution

Particle size effects on capture and matrix loading in HGMS

Abstract: The performance of a well characterized HGMS matrix on the collection of paramagnetic particles from a slurry of known particle density and particle size distribution was studied. Particular attention was paid to the capture as a function of time of different size particles and the resulting changes in the particle size distribution of the collected material. The recovery of material of different particle sizes and operating conditions was correlated in terms of a dimensionless ratio of magnetic and fluid drag forces acting on the particles.

Method and apparatus for measuring particle size

Abstract: The disclosure relates to an apparatus for measuring the size of gas entrained particles by detecting the rate of incandescent burning of the particles. Entrained particles are passed at a controlled velocity through a heated zone where they are gradually consumed. The radiant energy emitted by the burning particles is detected at varying locations along the path of flow through the heated zone. An indication of particle size distribution is obtained by deriving the third derivative of detected radiant energy intensity with respect to distance of flow through the heated zone.

Partikelgr6ssenverteilung und nattirliche Koagulation im Ziidchsee

Abstract: The size distribution of suspended particles in Lake Zttrich water shows always the same shape, irrespective of the total concentration of particles, depth or season. The particle size distribution can be described by a function of the form ,aN (d~) = n (dp) = A d~" m ddp where N (d~) = concentration of particles with diameters between dp and dp+ zld~ [cm-3], dp = particle diameter ~m], A = constant of the particle size distribution, n (~)= particle size distribution function, m was found to be about 3.5. Model calculations show that coagulation determines the particle size distribution. The lake model consists in three completely mixed parts: the epilimnion, the thcrmocline and the hypolimnion. The effect of outflow of particles by a river, sedimentation and coagulation on the particle size distribution were investigated.