Lecture 01 : Solid particle characterization

Summary

This online certification course introduces the fundamentals of particle, fluid, and solid processing, focusing on unit operations common across industries. It emphasizes the importance of understanding particulate solids, their unique properties, and the challenges they present compared to fluids. The course will cover fluid flow, mechanical processes, and various methods for characterizing particle size, highlighting the significance of these operations in industrial applications.

Takeaways

• 📘 The course focuses on the fundamentals of particle and fluid solid processing, emphasizing the importance of understanding common industrial processes known as unit operations.
• 🔍 Unit operations often involve particulate solids and include processes like filtration, distillation, and evaporation, which are crucial for separating components in various industries.
• 🏭 The construction details of unit operations can vary significantly between industries, even when the underlying principles remain the same, such as in distillation processes.
• 🔑 The course aims to explore the fluid flow and mechanical processes, which are key to understanding how to process and separate solid-fluid mixtures.
• 🧪 The physical state of particulate solids is complex and often more difficult to define than that of fluids due to their convoluted geometrical orientation.
• 🔄 The behavior of solids can be counterintuitive compared to fluids, as demonstrated by the tendency for solid particles to segregate rather than mix when agitated.
• 📏 Defining particle size and shape is essential for understanding the characteristics of particulate solids, with size and shape influencing properties such as settling rate and surface area.
• 🌐 For irregularly shaped particles, size can be characterized by equivalent spherical diameters based on properties like volume, surface area, or settling velocity.
• 📊 Particle size distribution is critical for understanding bulk solids in industrial applications, as it provides a statistical representation of the sample's size characteristics.
• 🔬 Various methods are used to measure particle size, including sieving, microscopy, sedimentation, elutriation, permeametry, electrozone sensing, and laser diffraction, each suitable for different size ranges.
• 📈 The script provides an overview of the particle size measurement techniques that will be discussed in detail in the next lecture, highlighting their relevance and limitations.

Q & A

What is the main focus of the online certification course on Fundamentals of Particle, and Fluid Solid Processing?

The main focus of the course is on understanding the fundamentals of particles and the processes involved in solid, fluid, and solid processing, particularly the fluid flow and mechanical processes where particulate solids are involved.

Why is it important to understand unit operations in various industries?

Understanding unit operations is important because they are common processes in various industries, and they often involve particulate solids. Mastery of these operations can lead to more efficient and effective industrial processes.

What are some examples of unit operations that involve particulate solids?

Examples of unit operations involving particulate solids include filtration, distillation, evaporation, and drying, where solids are separated from a suspension or moisture is removed from a solid surface.

How do the principles of fluid flow and heat transfer relate to the processing of particulate solids?

Fluid flow and heat transfer are fundamental to processes like filtration, where fluid transport or suspension transport is involved, and evaporation or drying, where heat exchange is crucial for removing moisture from solids.

What are some challenges in characterizing particulate solids compared to fluids?

Characterizing particulate solids is more challenging due to their convoluted geometrical orientation and the difficulty in defining their physical state, which can be counterintuitive compared to the behavior of fluids.

Why is it difficult to apply knowledge of fluid mixing to the mixing of solid particles?

Applying fluid mixing knowledge to solids can be ineffective because solid particles, when mixed, can lead to agglomeration or size separation rather than a uniform mix, due to their physical properties and interactions.

How does the size and shape of a particle influence its characteristics and behavior?

The size and shape of a particle significantly influence its characteristics, such as surface area, settling rate in a fluid, and even color in the case of nanoparticles. Irregularly shaped particles can be particularly challenging to characterize.

What is the concept of an 'equivalent sphere' when characterizing irregularly shaped particles?

An 'equivalent sphere' is a theoretical sphere that has a property, such as volume, surface area, or settling velocity, identical to that of an irregularly shaped particle. This concept simplifies the characterization of irregular particles by allowing them to be described using a single dimension.

What are some methods used to determine the size of irregularly shaped particles?

Methods to determine the size of irregularly shaped particles include equating the volume, surface area, or projected area of the particle with that of a sphere, and using properties like settling velocity or aperture size in screening to find an equivalent spherical diameter.

What is the significance of particle size measurement techniques in industrial applications?

Particle size measurement techniques are crucial for quality control, process optimization, and ensuring the desired properties of products in various industries, as they help in characterizing and controlling particle size distribution.

What are the limitations of different particle size measurement techniques, and how do they relate to the size range of particles?

Different measurement techniques are limited to specific size ranges. For example, sieving is effective for sizes larger than 50 microns, while microscopy, sedimentation, and permeametry are used for smaller particles. The choice of technique depends on the size range of the particles being measured.

Outlines

00:00

📚 Introduction to Particle and Fluid Solid Processing

The first paragraph introduces the online certification course on the Fundamentals of Particle, and Fluid Solid Processing. It emphasizes the importance of understanding unit operations common across various industries, which often involve particulate solids. The lecture aims to explore the characterization of solid particles and their role in processes like filtration, distillation, and evaporation. The course will cover fluid flow, heat transfer, mass transfer, mechanical processes, and thermodynamics, all of which are integral to the processing of particulate solids.

05:03

🔬 The Challenge of Characterizing Particulate Solids

This paragraph delves into the complexities of characterizing particulate solids compared to fluids, due to their convoluted geometrical orientations and varying physical states. It highlights the counterintuitive behavior of solids, such as the tendency for particle agglomeration when mixed, and the separation of particle sizes during vigorous shaking. The paragraph also underscores the importance of understanding individual particle attributes like composition, size, and shape, which are crucial for defining the characteristics of particulate solids.

10:04

📏 Defining Particle Size and Shape

The third paragraph focuses on the methods of defining the size and shape of particles, especially irregularly shaped ones. It explains how regular particles can be defined by their dimensions, while irregular particles are often equated to an equivalent sphere based on properties like volume, surface area, or surface area per unit volume. The paragraph also introduces the concept of particle size distribution for bulk samples and the significance of statistical average sizes in industrial applications.

15:09

🔍 Characterizing Irregularly Shaped Particles

This paragraph discusses the various methods used to characterize the size of irregularly shaped particles, such as equating their projected area on a plane to that of a sphere, or using the settling velocity as a basis for comparison. It mentions different types of diameters that can be used to represent particle size, including the equivalent volume diameter, Martin's diameter, and Feret's diameter, and emphasizes the need to choose the appropriate measurement method based on the specific application or requirement.

20:13

🛍️ Analogy of Particle Size Measurement in Everyday Life

The fifth paragraph uses an analogy to everyday shopping to explain the concept of defining particle size based on specific properties. It compares measuring the size of a pair of jeans to measuring the size of a bed, illustrating that different measurements are necessary depending on the context. The paragraph also outlines various methods for determining the size of irregularly shaped particles, such as using an equal area circle, Martin's diameter, and Feret's diameter, and explains the relevance of each method in different scenarios.

25:18

📈 Overview of Particle Size Measurement Techniques

The final paragraph provides an overview of the various techniques used to measure particle size, which will be covered in more detail in the next lecture. It lists methods such as sieving, microscopy, sedimentation, elutriation, permeametry, electrozone sensing, and laser diffraction, and notes that these methods are not universally applicable but are limited to specific size ranges of particles. The paragraph concludes by thanking the audience for their attention and looking forward to the next lecture.

Keywords

💡Particle Characterization

Particle characterization is the process of defining and measuring the properties of particles, such as size, shape, and composition. In the context of the video, this concept is crucial as it underpins the understanding of various unit operations in industries like fermentation and petroleum refining, where the behavior of particulate solids is critical for process efficiency.

💡Unit Operations

Unit operations refer to the basic physical operations used in industrial processes. The script mentions that these operations often involve particulate solids and are common across different industries. For example, distillation is a unit operation that occurs in both the fermentation and petroleum industries, highlighting the importance of understanding these fundamental processes.

💡Particulate Solids

Particulate solids are materials in the form of small solid particles. The script emphasizes that the study of particulate solids is the focus of the course, as they are involved in various unit operations such as filtration and distillation. The unique behavior of these solids, compared to fluids, is a key theme in the video.

💡Fluid Flow

Fluid flow is a subcategory of the study of how fluids, including liquids and gases, move. The script discusses fluid flow in the context of chemical engineering and its relevance to the transport of particles and suspensions, which is essential for understanding processes like filtration and solid fluidization.

💡Heat Transfer

Heat transfer is a process where thermal energy is exchanged between different systems or within a system. In the script, heat transfer is mentioned in relation to processes such as evaporation and condensation, which are unit operations that are part of the broader study of particle and fluid solid processing.

💡Mass Transfer

Mass transfer involves the movement of mass from one point to another, often driven by concentration differences. The script refers to mass transfer in the context of operations like gas absorption, distillation, and extraction, which are integral to the processing of particulate solids.

💡Mechanical Processes

Mechanical processes involve physical manipulations of materials to achieve a desired outcome. The video script discusses mechanical processes such as particle size reduction and enlargement, as well as solid screenings, which are important for altering the properties of particulate solids for various applications.

💡Thermodynamic Processes

Thermodynamic processes are those that involve changes in the energy states of a system. The script briefly touches on thermodynamic processes like gas liquefaction and refrigeration, which are relevant to the study of particle and fluid solid processing due to their impact on the behavior of materials.

💡Particle Size Distribution

Particle size distribution is a statistical representation of the range of sizes of particles in a sample. The script explains that defining the size of a single particle is not always helpful, and instead, understanding the distribution can provide a representative idea of the sizes present in an industrial scale sample of particulate solids.

💡Equivalent Sphere

An equivalent sphere is a theoretical sphere that has a property identical to that of an irregularly shaped particle. The script discusses using the concept of an equivalent sphere to simplify the characterization of irregularly shaped particles by equating properties such as volume, surface area, or settling velocity with those of a sphere, which is easier to define and measure.

💡Martin’s Diameter

Martin’s diameter is a measure of the size of an irregularly shaped particle, defined as the diameter of a circle with an area equal to the projected area of the particle. The script mentions Martin’s diameter as one of the methods to characterize the size of irregular particles, illustrating the various ways in which particle size can be determined.

Highlights

Introduction to the importance of understanding unit operations in various industries.

Unit operations involving particulate solids are crucial in processes like filtration and distillation.

Different unit operations are categorized based on processes such as fluid flow, heat transfer, and mechanical processes.

The course focuses on fluid flow and mechanical processes for processing solid-fluid mixtures.

The complexity of solid particles compared to fluids due to their geometrical orientation and physical state.

Counterintuitive behaviors of solid particles in mixing and settling compared to liquids.

Importance of understanding the attributes of individual particles such as composition, size, and shape.

Challenges in defining particle size and shape due to irregularity and lack of homogeneity.

Use of equivalent sphere concept to define size for irregularly shaped particles.

Different methods to determine the size of irregular particles based on volume, surface area, and other properties.

Significance of particle size distribution in industrial scale handling of bulk particles.

Influence of particle size, shape, and composition on the characteristics of solids.

Examples of different particle sizes in various commercial products and their measurement challenges.

Overview of particle size measurement techniques including sieving, microscopy, and sedimentation.

Limitations of different measurement techniques based on the size range of particles.

Importance of choosing the right measurement method based on the specific application or study focus.

Different types of diameters used to define the size of irregular particles, such as Martin’s and Feret’s diameters.

Practical examples of particle sizes in common products and the relevance of accurate measurement techniques.

Transcripts

Hello everyone.

Welcome to the very first class of this online certification course on Fundamentals of Particle

and Fluid Solid Processing.

Today we will be seeing that the first class on Solid particle characterization.

So, before I begin let me give you a introduction that why this course is important in case

you have missed or you have not seen the introductory lecture of this course.

So, the relevance of this course lies in understanding various processes that are common in various

industries.

We typically call them unit operations.

Now, several search operations include particulate solids and among them, several operations

also include separation of components of a mixture that is highly desirable in several

scenario.

So, basically unit operations that we typically club various common physical operations together

can also be broadly categorized in several processes.

We will see that in the next slide, but let me give you an example that what are the unit

operation processes.

For example, let us say in fermentation industry distillation happens similarly in petroleum

refinery distillation happens.

Now, both the processes are identical; the underlying principles are identical, but what

matters is the detail in construction of those units in different sectors or different industries.

Now as I said in numerous cases, this unit operation involves particulate solids which

are actually is the focus of this course.

So, here we will see that several to give an example that what are those operations,

where the particulate solids are involved.

Those are like filtration, sometimes distillation evaporations or drawing that involves this

particulate solids.

Now, infiltration what happens?

We separate solids from a suspension.

In distillation typically two different liquids are separated; in evaporation or drying, we

remove water or moisture from a solid surface.

Now, as I said that based on this underline processes, this unit operations are broadly

categorized in various several other processes that are the key features like fluid flow

phenomena, heat transfer processes, mass transfer processes, mechanical processes and some thermodynamic

processes.

So, any a typical industry with involve one or more of these processes.

Now in fluid flow now this basically these sub categories eventually are taught as a

separate subjects; core subjects in chemical engineering curriculum.

For example, in fluid flow that is the preliminary basic course that is desired to know the subject

in details where we study fluid transport or the suspension transport relevant to the

particle solids, filtration, solid fluidizations that helps us to get the solids from a mixture.

Similarly there is heat transfer where we study evaporation, condensation, heat exchange.

In mass transfer, we study gas absorption, distillation, extraction, adsorption, drying.

In mechanical processes, we study separate solids transport separately.

We also study particle size reduction as well as enlargement; we also study solid screenings.

In thermodynamic processes, we study gas liquefaction, refrigeration its and such phenomena.

So, the point is that in any industry or industrial operations will involve or can involve more

than one of these processes ok.

But the focus of this course lies on this two aspects that is the fluid flow and the

mechanical processes where we will see that the fundamentals of particles and how to separate

or how to process a solid fluid mixture.

So, with this preamble, I guess it is now clear that what we are going to cover.

Now when it comes to the particulate solids or let’s say the bulk solids or sometimes,

it is called the granular solids.

Why this is important?

The reason is that the solids; the concept of solids is difficult than the fluids because

it has convoluted geometrical orientation and defining its physical state is sometimes

difficult or most mostly it is difficult.

So, for example, general knowledge on fluid let us say liquid or gases, the concept if

you know that and if you try to implement that in the case of solids, it will not help.

And in fact, that perceptions are sometimes counterintuitive.

For example, to mix two liquids, what you do?

You mix, you take those two liquids put in some buckets or some places and then you vigorously

mix them.

If you do that for the solids; if you take different types of solid particles, you mix

them in a container and you shake it vigorously stir it, vibrate it.

It can happen; eventually what will happen that there will be a particle agglomerations

or particle size separation, instead of mixing that happened in liquid or the gas case.

Another example is that you take a steel ball or iron ball a heavy ball, you put that in

a container, then you pour sands inside the container.

So, basically the iron or the steel ball stays at the bottom of the container and it is filled

with the sand particles.

And then you shake it on a vertical plane.

What will happen?

The iron or the steel ball will come to the surface; open surface.

So, it will rise through the small particles which is completely different from the liquid

or the gas phases.

And again somehow, if you can introduce some gaseous phase of the liquid phase though the

bottom of that container immediately that steel ball will sink due to fluidization.

So, the point is that we need to study the solid classifications separately; its attributes

are different than the fluid phases.

So, what are the important attributes of an individual particle?

So, individual particle if you state it composition, size and shape; then possibly you can define

or understand its characteristic.

Like composition it helps the properties like to understand the different properties; like

density conductivity and all this things that can be determined if you know the compositions.

But again that is helpful; this knowledge is helpful if the composition is homogeneous,

but in most cases solid particles in solid particles that is not the case.

So, that is why this solids are complicated than the fluid.

Similarly size and shapes, these are also important features.

If it is a regular shape of the regular sized particle, then it is easy to define, but in

most cases it does not have a particular size or shape.

So, what happens; that if you define a particle size then several properties such as surface

area, surface per unit volume; it settling rate in a fluid can possibly be determined.

If you can define a particle shape, then it would be easier to understand what is the

characteristic of a particulate solid.

So, it can be of regular shaped particle or irregular shape particle.

Regular means like a spherical particle, cubic particle, cylindrical particle etcetera that

you can define by several different types of dimensions.

For example, a spherical particle if you define its diameter, then you can define that particle

shape as well as a size.

For the cubic or the cuboid particles, you have to define the three dimensions; for the

cylindrical also, you have to define its radius and the height.

But in case of irregular particle; for example, of broken glass; broken wheels windshield

of a car, if you see those shapes those are irregular shapes.

So, how do you define the size of such particles.

In industrial scale bulk amount of particles are handled at a time.

So, how do you define particle size of that complete system?

So, in that case determination of size of a single particle does not help you, what

helps is the particle size distribution.

And then if you get the particle size distribution, statistical average mean sizes can be obtained

which can give you one representative idea that what are the size is available that you

have in the case of industrial scale sample.

So, like particle size shape and the composition has significant influence on the solids characteristics

as well.

Like in case of nanoparticles when the size goes around 10 to the power minus 9 meter

that is the nanoscale.

Particle size actually changes the colour of that substance.

Now, the point is that how do we define a single particle size.

We will come to the sample of different particles when we will discuss the industrial scale

samples.

But let us at first focus that how do we single out a particle and how do we characterize

a single particle size.

In case of regular case, we have understood that it can be defined very easily by any

of these dimension that is in case of cuboid-three dimensions, in case of spherical the diameter,

in case of cylindrical; the radius and the height.

But in case of irregular shaped particles, what has been conventionally done is that

the size of irregular shaped particles has been equated with the size of an equivalent

sphere.

Now this, what is the equivalent sphere.

Now this equivalent definition depends on the chosen property that with which property

you want an equivalent sphere.

For example, that identical property can be of equivalent volume that you calculate the

volume of the irregular shaped particle and then the same volume of a sphere what would

be its diameter of the sphere that you can easily calculate, and that gives size of a

particle; irregular shaped particle.

Similarly, you can equate the surface area of irregular shaped particle with the equivalent

sphere having same or identical surface area.

There can be possibility that the surface area per unit volume may be same in both the

cases and then you determine the sphere.

Now, the point is that why we are sticking to that size of a equivalent sphere.

The point is that the spherical particle definition is very easy.

Sphere is symmetry in nature, it requires only one dimension to tell its size because

shape is already spherical.

So, size can be easily determined by only a single dimension because of its symmetry

in nature.

So, it brings a great deal of simplicity.

If we can find some kind of equivalence, the property equivalence with the sphere that

we are looking for when we are looking into a particular solid particle.

Similarly, the projected area on a plane normal to the direction of motion because of irregular

shape, it will have a different projection area.

But if you can get the projected area on a plane normal to the direction of its motion

and you equate that area with the area of a sphere and then calculate the spherical

a diameter.

Thus the diameter of the sphere, you can get another a particles in the size; I mean another

size of the same particle.

So, basically all these criteria again; if you equate that with the projected area of

a stable orientation; stable orientation means that irregular shaped particle.

So, when you try to measure its dimension through a microscopy, it would not sit on

the slide or on the plane on any direction or the orientation.

It will sit on its stable orientation.

So, on that stable orientation, what is the projection for the projected area that you

are looking or that you get from a microscopic image?

You equate that area with the equivalent surface area of a sphere and if the and find out the

dimension of the sphere or the radius or the diameter of the sphere, you get a characteristic

dimension of the irregular shaped particle of the size of the particle.

Similarly settling velocity as I said in my introductory lecture of this class that a

basic fluid mechanics knowledge is essential to understand this course.

So, the settling velocity you may have heard about Stokes’ law.

We will again cover or refresh your memory in the later of this course; later stage of

this course.

So, the point is that the settling velocity; that means, when particle is trying to settle

through a pool of liquid, it attains a velocity; that velocity if you equate that with the

equivalent sphere and then determine the diameter of that sphere.

You can get dimension or a size of a irregular shape particle having identical settling velocity.

And finally, or the other possibility can be that size of a square aperture through

which it passes through during the screening or the sieving operation, that how do we separate

different size particles.

We separate with take that on a screen, we shake it or vibrate it and then we separate

different size of particle through the overflow and the underflow.

Now, the particles that go through that square aperture, it can be equated with the similar

size sphere and then we find out its diameter.

So, the point is all this now this is not that all the exhaustive list.

There can be several other possibility of finding a dimension; a size dimension of a

irregular shaped particles.

These are the few representative and sometimes it is the mostly used ones.

Out of this very commonly used is the volume equivalent or equivalent volume spherical

diameter for the irregular shaped particle.

The point is that what I was trying to mention that even for single this irregular shaped

particle by doing all these analysis, we can find different dimensions of size or different

measurement of mean size.

For example if you take a irregular shaped particle and equate with all these varieties

of different property, you get different numbers in dimension.

So, which means a simple irregular shaped particle can be represented by various numbers

depending on the property that you choose to make it equivalent with the sphere.

So, how do we define?

That is why whenever we define a size of a irregular a shape particle; we have to tell

what is it is either it is a mean volume equivalent volume diameter of a sphere or its a, identical

surface area of a equivalent sphere.

The analogy you can draw that when you go for shopping that is say you have to buy a

pair of jeans, what you tell to the shopkeeper?

You tell your waist size or the circumference of your waist ok.

But if you try to buy or if you are going to buy let us say a bed ok, then you have

to tell your height.

So; that means, that based on your requirement you have to define your measurement property

ok.

So, let us take this irregular shaped particles.

Now what are the types or what are the common variety that we can have to define its size.

So, for this irregular shaped particle, what can happen?

One of the possibilities that we can draw a equal area circle that is exactly equal

to the projected area of this particle and then we find out the circle diameter.

So, this will be its equivalent size.

The other possibility can be that we draw a line bisecting that projected area and that

line or that dimension would be our diameter which typically calls the Martin’s diameter.

The third possibility can be that we draw two parallel planes or the parallel tangents

and find out what is the distance between the two parallel planes which is again a representative

diameter call the Feret’s diameter.

Now this is quite common because sometimes we measure a substance or a particulates size

or a single particle size by caliper.

So, caliper measurement typically gives this Feret’s diameter for the irregular shaped

particles.

So, the point is that as again this slide shows that for any irregular shaped particle,

you can have different diameters.

So, which one you need that is based on your requirement or the focus of your study that.

For example, if you are looking through the microscopy, you can get this equivalent circle

diameter or Martin’s diameter.

Again let me go back to the previous slide and if we see that when it is important to

understand the settling or the sedimentation part, we will be possibly looking at the identical

property equated with the settling velocity because it is more relevant to that applications.

So, based on the application or based on your application in hand, you choose your measurement

method to find out what is the equivalent irregular shaped particle size.

So, this is a slide that shows the typical sizes of various common products that are

typically available commercially.

This is the size range that is given in micron.

For example, the topmost is the bigger particle which is in the order of 10 to the power 5

micron which means in the order of meter scale that is a pelleted product.

For example, you can have let us say the coal from its mining stage some chunk of big chunks

of coals or maybe pelleted products, some catalyst; pelleted catalyst in this range;

in the meter submeter range.

The granular fertilizers, it comes in the range of 10 to the power 4 micron.

Again to refresh your memory, 1 micron is 10 to the power minus 6 meter.

Detergent, granulated sugars comes in the range of 10 to the power 3 micron; that means,

a 1000 micron level, then we have powdered sugar or the flour that we use regularly that

is in the order of 100 micron; one particle size in the order of 100 micron The toner

cartridges, a ceramics that we use in the order of 10 micron.

The photographic emulsions is now in the order of micron.

Then there are submicron particles like organic pigments and carbon blacks.

So, the point is that how do we measure a particle size.

So, this particle size measurement techniques, we will be discussing in detail in the next

lecture.

But let me give you an overview that what will be covering in the next lecture is that

different methods by which we typically characterize a single particle which are the sieving; which

are the sieving microscopy, sedimentation and elutriation, permeametry, electrozone

sensing, laser diffraction method.

So, most popular method is a sieving or the screenings, then it comes by looking through

microscopy.

There are other methods as I have mentioned here are the sedimentation elutriation.

So, these classifications or these measurement techniques are not arbitrary.

These measurement techniques cannot be applied for all the range of particle or the size

range of particles; these are limited to a particular size range.

For example, sieving or screening can be done for the size range more than 50 micron also,

beyond that you cannot sieve that there is no standard sieve that can help you to identify

a particle size below 50 micron.

In that case, we have to go to either microscopy or sedimentation or permeametry methods or

the other methods.

So, similarly based on the particle range we have to use our size measurement techniques

that we will be cover in the next lecture.

So, with this, I thank you for your kind attention and will interact with you in the next lecture.

Thank you.