McGill University – Department of Mining and Materials ...storage.googleapis.com/wzukusers/user-24977994/documents... · Robert P. Harrison, Ph.D. Department of Materials Engineering

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Robert P. Harrison, Ph.D. Department of Materials Engineering March 10, 2016

McGill University – Department of Mining and Materials Engineering Undergraduate Design Course MIME 452

Scale-Up of Industrial Processes

Robert P. Harrison, Ph.D.

Revision 1 / March 10, 2016

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Congratulations!

•  You just received a patent for your novel production method

•  On paper, the cost-per-tonne is lower than for the conventional process

•  Demonstrated at lab scale only…

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“Scale-Up”

1.  Introduction (10 min.)

2.  Theory and its Limitations (15 min.)

3.  The Empirical Approach (15 min.)

4.  Industrial Case Studies (15 min.)

5.  Critical Role of Engineers (5 min.)

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“Scale-Up”

1.  Introduction

2.  Theory and its Limitations

3.  The Empirical Approach

4.  Industrial Case Studies

5.  Critical Role of Engineers

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Example of Scale-Up: NASA Wind Tunnel Tests

•  Let’s start with something a bit more familiar…

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Scale-Up: Big Picture

Everyday Experience

Theory (Physics & Math)

50+ Years of Real

Projects

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HEAT TRANSFER: Baking a Cake

•  If you double a cake recipe, it no longer works –  Middle underbaked

•  Increase temperature or baking time? –  Edges overbaked

•  This is a heat-transfer problem: –  Radiation –  Convection –  Conduction

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Original recipe

Doubling all the amounts

Conduction

Radiation

Convection

Baking a Cake

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MASS TRANSFER: Upper Size Limit for Insects

•  Insects cannot grow above a certain size, because their cells get oxygen directly from the air, which must diffuse through pores located on the outside of their bodies

Image by Piotr Jaworski

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Water Droplets

•  You can suspend 1 mL of water from your fingertip, but not 100 mL from your elbow

•  The drop of water on your fingertip might eventually detach and fall to the ground, but the water droplets in fog never fall down

•  Fog is visible, but water vapour is invisible

Why is that?

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Water at Different Scales

Diameter: 10-1 m 1 Litre

The surface tension of water is ~70 mJ/m2, insufficient to maintain such a large droplet (Area ∝ R2, Volume ∝ R3)

Diameter: 10-2 m Raindrop Small enough to hold together…falls to the ground

. Diameter: 10-4 m Fog droplet

Small enough to be buoyed by air movement…water has refractive index of 1.33 so fog is visible (interface)

Diameter: 10-10 m Water vapour Invisible…no interface, just another molecule in the air

.

Single molecule

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“Scale-Up”

1.  Introduction





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Emergent Properties

•  The atomic scale never changes •  Properties like viscosity and surface tension are

“emergent properties” –  Like traffic patterns emerging from the capabilities of a single

vehicle

•  Clusters of clusters of clusters of clusters of molecules –  Different for each macroscopic scale

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The Age of Nanotechnology

August 2010: German team captured images of an individual electron

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We Know the Forces

•  According to physicists there are only four forces:

– Gravity – Electrical – Strong Nuclear – Weak Nuclear

Only occur inside an atom’s nucleus… for process engineers, exponential radioactive decay is good enough

Charles-Augustin de Coulomb (1736-1806)

Sir Isaac Newton (1642-1727)

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Forces

•  According to physicists there are only four forces:

– Gravity – Electrical – Strong Nuclear – Weak Nuclear

Things falling.

Everything else: •  Combustion •  Chemical reactions •  Viscosity •  Surface tension •  Phase changes •  Colour •  Biochemistry •  Solidness of objects •  You-name-it…

Note that this includes

magnetism (a result of Relativity)

Albert Einstein (1879-1955)

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Starlings on Ot Moor, England

Play VIDEO http://www.youtube.com/watch?v=XH-groCeKbE

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Metaphor for Molecules: A Flock of Starlings •  There is no leader…each bird is reacting to the 6-7 birds that

surround it •  Too fast to be “thinking”…this must be pure instinct based on

simple rules •  The flock has a constant density (centre vs. edge)…there

seems to be an ideal distance between the birds, much like the average distance between molecules in a liquid

•  There is a clear demarcation between flock and empty air…similar to surface tension…maybe each bird is avoiding exposure to predators?

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Differential Equations

Newton’s Laws of Motion

Maxwell’s Equations

Ohm’s Law

Fourier’s Law Fick’s Law

Coulomb’s Law

Laws of Thermodynamics

Newton’s Law of Gravity

Wave Equations

Faraday’s Law

Conservation Laws

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Deceptively modern-looking diagrams from Newton’s Philosophiae Naturalis Principia Mathematica (1687)

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Great News!

1.  We know all about the particles. 2.  We understand the forces involved. 3.  We know how groups of particles behave. 4.  We have Differential Equations for all the most important

physical phenomena.

First problem: Most Differential Equations are intractable

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Why Not Use a Computer?

•  Numerical Methods…computing power limitations –  Cake: 1025 molecules –  Chemical reactions: femtoseconds

•  Quantum Physics

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O. Smirnova, “Spectroscopy: Attosecond Prints of Electrons”, Nature, Vol. 466, 2010, 700‑702 (image credit: Christian Hackenberger, Ludwig Maximilians University of Munich)

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Why Not Use a Computer?

•  Numerical Methods…computing power limitations –  Cake: 1025 molecules –  Chemical reactions: femtoseconds

•  Quantum Physics –  Probabilistic

•  Chaos Theory –  Physical systems are extremely sensitive to initial conditions

We are already in deep waters…

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Example of a “Chaotic” System: Drinking Bird Toy

https://www.youtube.com/watch?v=Yk71GY02diY

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Simple Example of Chaos Theory

•  Absurdly simple example of Chaos Theory:

XN+1 = 4*XN*(1-XN)

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Simple Example of Chaos Theory

•  Absurdly simple example of Chaos Theory:

XN+1 = 4*XN*(1-XN)

•  The so-called “Butterfly Effect”

– Disturbance of 10-16 introduced at iteration #25…totally different behaviour by iteration #85

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Chaos Theory Example

Disturbance of 10-16

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“Scale-Up”

1.  Introduction





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Symmetry in Physics

Mirror image Different location

Different time

Monday Tuesday

Get the same result

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Symmetry does NOT apply to scale

A larger clock would run too slowly (pendulum)

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The trouble with engineers is they believe anything that’s

written in a book.

- British physicist Derek L. Livesey (1923-1992)

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Extrapolating from Laboratory Data

Central Question: Can the correlations found in the laboratory be extrapolated

to the industrial scale? Recovery (%)

Throughput (kg/h)

Lab Scale Commercial

Scale

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Extrapolating from Laboratory Data

Recovery (%)

Throughput (kg/h)

Lab Scale

Pilot Scale

Commercial Scale

We need to test.

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From Perry’s Handbook, 6th Ed.

“It is generally accepted that the design of a commercial-scale chemical reactor, which is at the heart of a chemical plant, cannot be accomplished by a purely theoretical approach alone.

”A satisfactory scale-up procedure may require a

stepwise empirical approach in which the size of the reactor is increased successively, with a desired commercial size as the goal.

“A purely empirical method would be time-consuming and

expensive…a number of alternative semi-empirical methods have been proposed.”

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Demo Plant

Commercial

At each scale get different behaviour: heat and mass transfer, conduction vs. convection, laminar flow vs. turbulent, etc.

Study different problems at different scales

600 kg/h 6 t/h 60 t/h

x 10 x 10 Lab

1 kg

x 10

Pilot Plant

Idea Inspired thinking

Test-tube / batchwise

Large enough to provide adequate

platform for scale-up

Fully integrated; essentially a miniature

commercial plant

Full-size plant

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The “Scale-Up Factor”

•  To process engineers this means the ratio of the throughputs = larger ÷ smaller –  Note that to mechanical engineers this can refer to length (cube root of

volume)

•  Typically 5 to 15, but highly variable

•  Some examples in the assigned reading…

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Scale-Up Techniques

•  Geometric similarity vs. non-geometric

– Area ∝ L2 – Volume ∝ L3

•  Chemical similitude…fooling the atoms! – The similar variable – Dimensionless groups

•  Fluid dynamics at different scales

– Computer modelling

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The “Similar” Variable

•  Simple example: Mixer

•  Possible choices of similar variable –  Impeller tip speed –  Power per unit volume –  Torque per volume –  Equal solids suspension –  Blend time –  …

•  Comes down to judgement

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Equipment Challenges

•  Easy in lab…hard at full scale –  Thickness of walls won’t support weight

•  Health & Safety –  Small leaks or power surges in the lab → human hazard at

full scale

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Lab vs. Commercial

•  Homogenous •  Steady state •  Equilibrium •  Pure •  Laminar •  Measurable •  Visible

•  Heterogeneous •  Non steady state •  Convection •  Turbulent flows •  Dead zones •  Accumulation •  Heat loss •  Difficult to see/measure

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Example of Pilot Plant

USDA Pilot plant for Biofuel Research (http://www.arserrc.gov/ccse/EngineeringSupportGroup.htm)

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“Scale-Up”

1.  Introduction





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Industrial Case Studies for Students

•  Seven examples of scale-up failures and successes –  Drawn from over 50 years of full-scale industrial projects

•  Fictionalized as Projects A through G

•  When classifying the projects, failure was defined as: –  10% over budget –  Start-up three months late, or –  Longer than one year to reach design capacity.

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Summary of 7 Case Studies

Project Categ. Outcome Key steps

skipped Length of

development steps (years)

A NP Success None 12 B NP Success None 11 C NP Success None 17 D NC Success None 2 E NP Failure Demo 2 F NP Failure Demo 2 G NP Failure None 9.5 NP = new process, NC = novel combination of established unit operations The length of time spent on the development steps was time spent directly on each phase, excluding engineering work carried out between stages

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Homework Questions

1.  Name two common characteristics of the successful case studies.

2.  Identify two common characteristics of the failures.

3.  What differences did you notice between a new process and a novel combination of established unit operations?

4.  Why do you think that Projects E and F obtained financing but were poorly planned, whereas Project G was well planned but did not obtain financing?

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In General: Common Characteristics of the Successful Case Studies

•  All key development steps were addressed •  The length of time spent directly on the development steps for a

new process was over ten years (Shorter development times are sufficient for novel combinations of established unit operations)

•  The scale-up factors for a new process from the demonstration to commercial plant were in the order of ten (Larger scale-up factors are allowable for novel combinations of established unit operations)

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In General: Common Characteristics of the Failures

•  Skipping the demonstration phase •  Spending only two years on the key development

steps •  Financing problems

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Project A (Successful)

Project E (Failure)

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“Scale-Up”

1.  Introduction





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The Human World

•  $$$ •  Deadlines •  Hierarchies •  Personalities •  Market Trends •  Politics

Human beings have the last word

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The Physical World

Mother Nature has the last word

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Human Nature

It’s a fact of human nature that the easiest person to fool is yourself

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Science is a Disbelief System

royalsociety.org

•  The Royal Society – Published Newton’s Principia – Motto is Nullius in Verba

– “Take nobody’s word for it”

•  A truly scientific approach assumes:

– All books are wrong! – Everyone you ever met was lying!

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Why are scientists and engineers so critical to decision-making?

RMS Titanic

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Why are scientists and engineers so critical to decision-making?

RMS Titanic

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McGill University – Department of Mining and Materials ...storage.googleapis.com/wzukusers/user-24977994/documents... · Robert P. Harrison, Ph.D. Department of Materials Engineering