PELAYO, JONH VINCENT D.
SA4
CHE 3121 | 8:30-11:30; 1:30-6:00 WTH | 3496
Activity 1: Motion of Particles through a fluid in the Industry
Enumerate and describe the 5 situations in the industry where the concepts of motion
of particles through a fluid are used.
1. Solid-Liquid Separation
Liquid-solid separation involves the separation of two phases, solid and liquid, from
a suspension. It is used in many processes for the: 1. recovery of valuable solid component
(the liquid being discarded); 2. liquid recovery (the solids being discarded); 3. recovery
of both solid and liquid; or 4. recovery of neither phase (e.g., when a liquid is being
cleaned prior to discharge, as in the prevention of water pollution). In solids
concentration, part of the liquid may be removed by (gravity or centrifugal) thickening
or hydrocycloning to reduce liquid volume throughput load on the filter.
2. Particle transport and deposition
Aerosol particle transport and deposition in vertical and horizontal turbulent duct
flows in the presence of different gravity directions are studied in industry. Two-phase
flows involving dispersed particle and droplet phases are common in a variety of natural
and industrial processes, such as aerosols, blood flow, emulsions, and gas-catalyst
systems. Accurate prediction methods for the transport, impaction, and deposition, and
fate of micro- and nanoparticles are needed, especially methods that can be applied
across wide ranges of fluid-flow conditions and particle sizes.
3. Fluidization
Fluidization is a process in which solids are caused to behave like a fluid by blowing
gas or liquid upwards through the solid-filled reactor. Fluidization is widely used in
commercial operations; the applications can be roughly divided into two categories, i.e.,
physical operations, such as transportation, heating, absorption, mixing of fine powder,
etc. and chemical operations, such as reactions of gases on solid catalysts and reactions
of solids with gases etc. The fluidized bed is one of the best-known contacting methods
used in the processing industry, for instance in oil refinery plants.
4. Flotation
Flotation is the process of separating small particles of various materials by treatment with
chemicals in water in order to make some particles adhere to air bubbles and rise to the
surface for removal while others remain in the water. The greatest application of froth
flotation is in the concentration of minerals, but one use in the food industry is in the
separation of small particles of fat from water. Dissolving the air in water under pressure
provides the froth. On the pressure being suddenly released, the air comes out of solution
in the form of fine bubbles which rise and carry the fat with them to surface scrapers.
5. Classification
Classification implies the sorting of particulate material into size ranges. Use can
be made of the different rates of movement of particles of different sizes and densities
suspended in a fluid and differentially affected by imposed forces such as gravity and
centrifugal fields, by making suitable arrangements to collect the different fractions as
they move to different regions.
Classification is also employed in direct air dryers, in which use is made of the
density decrease of material on drying. Dry material can be sorted out as a product and
wet material returned for further drying. One such dryer uses a scroll casing through which
the mixed material is passed, the wet particles pass to the outside of the casing and are
recycled while the material in the centre is removed as dry product.
References:
Dechsiri, C. (2004). Particle Transport in Fluidized Beds: Experiments and Stochastic Models
. Groningen: s.n.
Erick S. Vasquez, Keisha B. Walters & D. Keith Walters (2015) Analysis of Particle Transport
and Deposition of Micron-Sized Particles in a 90° Bend Using a Two-Fluid Eulerian–
Eulerian Approach, Aerosol Science and Technology, 49:9, 692-704, DOI:
10.1080/02786826.2015.1062466
MECHANICAL SEPARATIONS. (n.d.) Retrieved from https://nzifst.org.nz/resources/
unitoperations/documents/UnitopsCh10.pdf
Wakeman, R.J. (n.d.). LIQUID-SOLID SEPARATION. DOI: 10.1615/AtoZ.l.liquid-
solid_separation. Retrieved from http://www.thermopedia.com/content/928
/#:~:text=Liquid%2Dsolid%20separation%20involves%20the,many%20processes%2
0for%20the%3A%201.&text=In%20solids%20concentration%2C%20part%20of,throu
ghput%20load%20on%20the%20filter.
