Introduction to Chemical Engineering

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Introduction to Chemical
Engineering

August 2, 2010

Vince Siu

vince_siu@brown.edu


Overview


What is Chemical Engineering?


Fundamental Principles


Case Study: High Fructose Corn Syrup



Guest Speaker: Prof. Hurt


Chemical Engineering Lab Tours


August 28, 1859
-

Titusville, Pennsylvania

Lubbock, Texas

Haifa, Israel

9 million tons (66 million barrels) of crude oil/ year

What is Chemical Engineering?

The integration of knowledge from the basic

sciences with engineering fundamentals to:


Convert raw materials into valuable products


To design and manufacture devices


Sustainability of the environment



This is accomplished by:


Chemical reactions (making and breaking of bonds)


Catalysis (accelerating chemical reactions)


Separation, purification of complex chemical mixtures






Convert Raw Materials into Valuable
Products


Crude Oil


Gasoline, Jet Fuel, Monomers


Monomers


Polymers (
ethylene


polyethylene)


Silicon crystals


Semiconductors, integrated
circuits


Inorganic Precursors


Ceramics


Corn Starch


High Fructose Corn Syrup

Design and Manufacture Devices


Biomedical devices (artificial kidney, hearts)


Chemical plants (paper, plastics, fertilizers)


Electronics


Diagnostic devices


Drug delivery devices


Novel materials (polymers, fibers, ceramic)


Energy devices (batteries, fuel cells)


Specialty chemicals (foods, flavors, fragrances)

Sustainability of the Environment


Degradation of toxic wastes in groundwater


Waste Treatment


Zero emission design

Chemistry vs. Chemical Engineering


Chemists:

Design new molecules and
synthesizes new formulas


Work in
grams
of materials



Chemical Engineers:
Design equipment and
processes for large
-
scale chemical
manufacturing


Work in
tonnes

of materials

Ammonium Nitrate


Texas

City Disaster


April 16, 1947


Mid
-
morning fire on SS
Grandcamp

that
detonated 23,000
tonnes

of NH
4
NO
3


Killed 581 people


Triggered first class action lawsuit against US
Government

Bhopal Gas Tragedy


Union Carbide India Limited pesticide plant,
Bhopal, India
-

December 2
-
3, 1984


3787
-

15,000 deaths


1
-
naphthol

chloroformate

carbaryl

Factors leading to the Bhopal disaster



The use of hazardous chemicals (MIC) instead of less
dangerous ones


Storing these chemicals in large tanks instead of over 200
steel drums.


Possible corroding material in pipelines


Poor maintenance after the plant ceased production in the
early 1980s


Failure of several safety systems (due to poor maintenance
and regulations).


Safety systems being switched off to save money

including the MIC tank refrigeration system

A Chemical Engineer’s Curriculum


Lots of Math, Chemistry and Physics


Fundamental Classes


Heat and Mass Transfer


Chemical Thermodynamics


Chemical Kinetics


Fluid Mechanics


Units of Chemical Processes: chemical reactors,
bioreactors, distillation columns, heat exchangers


Design Chemical Process


integrate process units
with regard to economics, safety and environmental
impact

The Fundamentals

The volumetric flow rate of CCl
4

(


= 1.595 g/cm
3
) in a
pipe is 100.0 cm
3
/min. What is the mass flow rate of
the CCl
4
?

Each year 50,000 people move into a city, 75,000
people move out, 22,000 are born and 19,000 die.
Write a balance on the population of the city.

A

feed

stream

of

pure

liquid

water

enters

an

evaporator

at

a

rate

of

0
.
5

kg/
s
.

Three

streams

come

from

the

evaporator
:

a

vapor

stream

and

two

liquid

streams
.

The

flow
-
rate

of

the

vapor

stream

was

measured

to

be

4

X

10
6

L/min

and

its

density

was

0
.
004

kg/m
3
.

The

vapor

stream

enters

a

turbine,

where

it

loses

enough

energy

to

condense

fully

and

leave

as

a

single

stream
.

One

of

the

liquid

streams

is

discharged

as

waste,

the

other

is

fed

into

a

heat

exchanger,

where

it

is

cooled
.

This

stream

leaves

the

heat

exchanger

at

a

rate

of

0
.
1893

kg/
s
.

Calculate

the

flow

rate

of

the

discharge

and

the

efficiency

of

the

evaporator
.

Mass Balance

Heat Transfer

A

square

silicon

chip

(
k

=

150

W/
m

K
)

is

of

width

w

=

5

mm

on

a

side

and

of

thickness

t

=

1

mm
.

The

chip

is

mounted

in

a

substrate

such

that

its

side

and

back

surfaces

are

insulated,

while

the

front

surface

is

exposed

to

a

coolant
.


If

4
W

are

being

dissipated

in

circuits

mounted

to

the

back

surface

of

the

chip,

what

is

the

steady
-
state

temperature

difference

between

back

and

front

surfaces?

Heat Transfer Cont’d

If the front surface is exposed to the flow of a coolant at
T= 15

C. For reliability, the chip temperature must not
exceed T = 85

C. If the coolant is air and the
corresponding convection coefficient is
h

= 200 W/m
2

K,
what is the maximum allowable chip power? If the coolant
is a dielectric liquid for which
h

= 3000 W/m
2

K, what is
the maximum allowable power?

Case Study:

High Fructose Corn Syrup

High Fructose Corn Syrup


Milestones


1957


Process developed by Richard O. Marshall
and Earl R.
Kooi


Up until 1970: sucrose used as a main sweetener


1975


1985


HFCS introduced to processed
foods and soft drinks


Common forms: HFCS 42 and HFCS 55

Soft Drinks

95%

Baked

Goods

25%

Diary

30%

Processed

Foods

45%

Sold in a bushel:
56 pounds of wet corn

(48.1 lb of dry corn + 7.9 lb of water)

Milling Process

Corn

Oil

1.6
lb

Cornmeal

2.5
lb

Animal Feed

12.5

lb

Starch

31.5
lb

Water

7.9

lb

Extract

Weight/Bushel

Cost/Pound

Cost/Bushel

Corn

Oil

1.6 lb

$0.27/lb

$0.43/bushel

Cornmeal

2.5

lb

$0.132/lb

$0.33/bushel

Animal Feed

12.5 lb

$0.044/lb

$0.55/bushel

Starch

31.5

lb

?

?

Water

7.9 lb

---

----

$1.31/bushel

Raw

Material

Weight/Bushel

Cost/Pound

Cost/Bushel

Wet Corn

56 lb

$0.047/lb

$2.63/bushel

Cost Analysis of Harvesting Corn

Corn Starch

High Fructose
Corn Syrup


Liquefication


G
-
G
-
G
-
G
-
G
-
G





G, G
-
G, G
-
G
-
G


Saccharification


G
-
G, G
-
G
-
G






G, G, G, G, G


Isomerization


Glucose








Fructose

α
-
amylase

Glucoamylase

Glucose
isomerase

Corn Starch

Other Extracts

Starch Purification

Liquefaction

Saccharification

Isomerization

Separator

55% HFCS

42% HFCS

α
-
amylase

plant

glucoamylase

plant

glucoisomerase

plant

3 hrs, pH 6
-
7, Initial: 300F, 30
min, Heat: 185F, 30 min, Cool:
140F, 30 min

40
-
90 hours, pH 4, 140F

30 min process, pH
7, 140
-
150F

Composition

%

Fructose

% Glucose

% Solid

HFCS 42

42

58

70

HFCS 55

55

45

70

Raw

Material

Weight/Bushel

Cost/lb

Cost/Bushel

HFCS 42

31.5

lb

$0.18/lb

$5.67

HFCS 55

31.5 lb

$0.20
/ lb

$6.30

Extract

Weight/Bushel

Cost/Pound

Cost/Bushel

Corn

Oil

1.6 lb

$0.27/lb

$0.43/bushel

Cornmeal

2.5

lb

$0.132/lb

$0.33/bushel

Animal Feed

12.5 lb

$0.044/lb

$0.55/bushel

Starch

31.5

lb

$0.18/
lb

$5.67/bushel

Water

7.9 lb

---

----

$7.42/bushel

Raw

Material

Weight/Bushel

Cost/Pound

Cost/Bushel

Wet Corn

56 lb

$0.047/lb

$2.63/bushel

Cost Analysis of Harvesting Corn