Introduction to Chemical Engineering

July 27, 2010Vince Siu

vince_siu@brown.edu

Overview

• What is Chemical Engineering?• Fundamental Principles• Case Study: High Fructose Corn Syrup

• Chemical Engineering Lab Tours

August 28, 1859 - Titusville, Pennsylvania

Lubbock, Texas

Haifa, Israel9 million tons (66 million barrels) of crude oil/ year

What is Chemical Engineering?

The integration of knowledge from the basicsciences 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

€

HNO3 + NH3 ⏐ → ⏐ NH4NO3

• Texas City Disaster – April 16, 1947• Mid-morning fire on SS Grandcamp that

detonated 23,000 tonnes of NH4NO3

• 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 CCl4 ( = 1.595 g/cm3) in a pipe is 100.0 cm3/min. What is the mass flow rate of the CCl4?

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 106 L/min and its density was 0.004 kg/m3. 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 TransferA square silicon chip (k = 150 W/mK) 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 4W 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= 15C. For reliability, the chip temperature must not exceed T = 85C. If the coolant is air and the corresponding convection coefficient is h = 200 W/m2K, what is the maximum allowable chip power? If the coolant is a dielectric liquid for which h = 3000 W/m2K, 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 ExtractsStarch Purification

Liquefaction

Saccharification

Isomerization

Separator

55% HFCS42% HFCS

α-amylaseplant

glucoamylaseplant

glucoisomeraseplant

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