Separation of Particle from Solid-Gases Flashcards
What is a PRIMARY purpose of gas-solid separation?
To improve air quality
Dust particles are typically larger than what size?
10 micrometers
What property of a particle is MOST important for gas-solid separation using simple
methods?
Size
What is the main resistance to motion for particles smaller than 100 micrometers in a gas
stream?
Viscosity
What is the unit typically used for particle size in gas-solid separation?
Micrometers
In gas permeation membranes, what is the main driving force for separation?
Pressure difference
Flat membranes offer what advantage in gas permeation processes?
Ease of fabrication
Which type of membrane has the highest membrane area per unit volume in gas permeation
processes?
Hollow fiber membranes
In cross-flow models for gas separation by membranes, which stream is typically assumed
to be in plug flow?
Feed stream only
In the complete-mixing model for gas separation by membranes, what is a limitation?
It is not accurate for high recovery processes.
In gas-solid separation, what can be recovered as a valuable product in dry state?
Powdered catalyst
What is the relationship between aerodynamic diameter and the settling velocity of a
particle?
They are directly proportional.
In gas permeation, what is the effect of temperature on permeability generally?
Permeability decreases significantly.
What is the main advantage of using complete-mixing models for gas separation by
membranes?
They are simpler to calculate compared to other models
Gas permeation membranes rely on a _____ as the driving force for separation
pressure difference
In a cyclone separator, the _____ force acts on a particle in the outward radial direction.
centrifugal
Early gas permeation membranes were limited by their low _____ .
permeability
The ideal separation factor (α) in gas permeation represents the ratio of the _____ of two
components in the mixture.
permeabilities
The _____ of a gravity settling chamber is determined by the particle trajectory within
the unit.
efficiency
(A) Gas-solid separation processes are always used to improve air quality. (B)The size of
a particle is the only factor affecting its settling velocity in a gas stream
Both statement A and B are False
Explanation (A) -While improving air quality is a common application, gas-solid separation
can also be used to recover valuable products or remove harmful pollutants from process
streams in various industries.
Explanation (B) - Particle size is a crucial factor, but other factors like particle density, shape,
and the gas viscosity also influence settling velocity
The separation of solid particles from a suspension consists of fine particles of different
materials in water using a flotation technique depends upon the differences in the
surface properties of the solid particles being used
Theoretical cut particle size for a gas cyclone is
The theoretical size of the standard
Which of the three phases of matter (solid, liquid, or gas) has particles separated by the
least amount of distance?
solid
The accurate prediction of permeabilities of gases in membranes is generally not possible, and experimental values are needed.
Permeability of membranes
The grade efficiency of gravity settling chambers can be calculated based on particle trajectory within the unit. The best-established models of collector performance
are those for fibrous filters and fixed-bed granular filters, in which the structures and fluid-flow patterns are reasonably well defined.
Only the first statement is true
Inertial separators in which particles are separated from the gas by inertial impingement
collecting bodies arrayed across the path of the gas stream.
Impingement Separators
It is a performance of a gas-solids separation device is most commonly expressed as the ______ n, the weight ratio of the dust collected to the dust entering the
apparatus.
Collection efficiency
The feed enters the cyclone _____ near the top and is given a spinning motion as it enters the _____.
Tangentially, chamber proper
Which of the following applications of cyclones is not found in industries involved with fluid-particles processing?
Pharmaceutical
It is in the opposite direction to the particle’s centrifugal force because it is on a volume of fluid that is missing compared to the surrounding fluid.
buoyant force
In a conventional reverse-flow cyclone, the _________ usually enters a cylindrical or conical chamber tangentially at one or more entrances (usually
rectangular in cross section) and leaves through a central opening
dust-laden gas
In deriving theoretical models for gas separation by membranes, isothermal conditions and negligible pressure drop in the feed steam and permeate stream are
_______
generally assumed
At what percent efficiency is it possible for a coarse dust to be collected wherein a fine dust may be separated with lower efficiency in the _____ operating at exactly the same conditions?
100% efficiency , same unit
Gravity collectors are generally built in the form of long, empty, horizontal, rectangular chambers with an inlet at one end and an outlet at the side or top of the other end.
Inlet , Outlet
What are the two types of solid dispersed in gases?
Fume and Dust
For preliminary selection, the analytical cut diameter can be estimated from the particle-size distribution of the incoming dust
Particle-size distribution
Very fine particles tend to agglomerate into a loose,_______ whereas coarse particles may
be nonporous and dense
Porous structure
It plays an important role in its ability to be entrained and remained in suspension.
Particle Density
In a reverse flow cyclones, the gas moves in a double vortex with a gas initially spiraling downward at the outside after it enters the inlet,, the flowing upward in the center of cyclones before it exist
flow pattern
For any separators device, the relative contribution of various collection mechanism depends on what characteristics
Particle and gas characteristics
Devices that particles are separated from a dust-laden stream when the direction pf gas flow is line but continue to be concentrated in the dust stream
Louver and Baffle Collectors
In a type of permeates it says (A)In a membrane process high-pressure feed pas is supplied to one side of the membrane and permeates normal to the membrane.(B) The
permeate leaves in a direction normal to the membrane, accumulating on the low-pressure side
The both statement is true
The particle size on a cumulative weight percent oversize distribution curve that is numerica
the _______
desired overall collection efficiency of the gas-solid separation device.
The ________ measurement is one of the common methods for obtaining a relative long-period evaluation of particulate air pollution
dust-fall
Dusts usually result from mechanical disintegration of matter.
Fuse are submicrometer dispersed solids formed by processes such as combustion,
sublimation, and distillation.
Only the first statement is true
Due to______, the particles do not follow the gas streamlines but continue to be concentrated in the dust stream.
Inertia
The tangential entry of gas creates a swirling flow within the cyclone body that imparts a substantial centrifugal separating force on the particles
Imparts
When a separator element is operated at low recovery, there is a minimal change in
______
Composition
Which of the following example given for Chemical in fluid-particle processing is not
included?
Distillating
For the design of a system there are _____ variables in the complete-mixing model
seven
