A Course in EnvironmentallyConscious Chemical Process Desi gn

Joan F. Brennecke and Mark A. Stadtherr

PSE 2000Keystone, CO

July, 2000

PSE 2000 2

• Motivation and Objectives

• Course Components

• Design Projects

• Teaching Experience and Assessment

• Related Work

OutlineOutline

PSE 2000 3

• The chemical industry is the major source of toxicpollutant release in the US (Anastas, 1994).

• Efforts to address this are shifting from remediation toprevention (“benign by design”).

• Pollution prevention is an increasingly important part ofthe average chemical engineer’s job responsibilities.

• Pollution prevention concepts must be incorporated intothe chemical engineering curriculum– Materials (lectures, problems, projects) for core courses.– Specialized courses.

MotivationMotivation

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• To educate students on the real cost of operatingprocesses that release pollutants.

• To provide students with strategies to minimize orreduce the environmental impact of a currentprocess.

• To examine the design of processes using newtechnologies that eliminate pollution at the source.

Objectives

CHEG 498B EnvironmentallyConscious Chemical Process Desi gn

CHEG 498B EnvironmentallyConscious Chemical Process Desi gn

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• Introduction to pollution prevention

• Environmental regulations

• New technology and current research

• Design projects: Comparison of conventional

processes with new environmentally benigntechnologies

Course ComponentsCourse Components

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• The waste management hierarchy: prevention vs.remediation.

• Scientific bases for environmental challenges• Waste audits and inventories: TRI, AIRS, BRS• Life cycle analysis• Industrial ecology and process integration• Common sense “housekeeping” solutions• Engineering modifications• Allen and Sinclair Rosselot, Pollution Prevention for

Chemical Processes, Wiley (1997).

Introduction to Pollution PreventionIntroduction to Pollution Prevention

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• Know your legal responsibilities.

• Impetus for the development of new technologies andpollution prevention strategies.

• Discussion driven by scenarios.

• Lynch, A Chemical Engineer’s Guide toEnvironmental Law and Regulation, NationalPollution Prevention Center (1995).

Environmental Re gulationsEnvironmental Re gulations

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• Raise awareness of types of new technology andongoing research

• Process Integration: Mass Exchange Networks

• Solvent substitution– Liquid and supercritical carbon dioxide: dry cleaning, spray

painting, separations and reactions– Room temperature ionic liquids: reactions and separation– Aqueous solvents in cleaning applications

New Technolo gy and Current ResearchNew Technolo gy and Current Research

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• Alternative raw materials or intermediates– Adipic acid from glucose– Road salt from lactose– Urethanes from amines and CO2 (i.e., without phosgene and

isocyanates)

• More selective catalysts and reaction systems– Optimal distribution of catalyst on support– Catalytic membrane reactions– Effect of mass transfer on selectivity in packed beds

New Technolo gy and Current ResearchNew Technolo gy and Current Research

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• Case studies that compare designs of conventionalprocesses to those using new benign technologies.– Decaffeination of coffee– Extraction of soybean oil– Production of p-nitroaniline

• Students develop preliminary designs.

• ASPEN PLUS simulations with costing and economicevaluation– Identification of environmental issues.– Evaluation of a variety of scenarios.

• Good framework for discussion of ethical issuesconcerning the value of inherently safer processes.

ProjectsProjects

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Decaffeination using supercritical carbon dioxide

vs.

Conventional “water process” using

methylene dichloride

Project 1: Decaffeination of CoffeeProject 1: Decaffeination of Coffee

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Ext

ract

ors

Beans in

Water in

dryer

Beanrestoration

Water + Caffeine + Aromas and Flavors

MeCl2 MeCl2/water purge

BeanProduct

Caffeinein MeCl2

Water+ A&F

Caffeine Extraction - Water ProcessCaffeine Extraction - Water Process

LL E

xtra

ctor

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dryerConcentrator

BeanProduct

Water in

Aqueouscaffeine byproduct

Beans in

CO2/caffeine

water

CO2 recycleE

xtra

ctor

Water/caffeine

Fla

sh

CO2makeup

LL e

xtra

ctor

Caffeine Extraction - Su percritical CO 2Caffeine Extraction - Su percritical CO 2

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Extraction with supercritical CO2

vs.

Extraction with hexane

Project 2: Extraction of Soybean OilProject 2: Extraction of Soybean Oil

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Soybean Oil Extraction - Hexane ProcessSoybean Oil Extraction - Hexane Process

Soybeanflakes

Hexane

Aqueous waste

Steam

SoybeanMeal

Water

SoybeanOil

Lecithin

Dryer

Evaporator

Decanter

Degummer

Desolventizer

Ext

ract

or

Stripper

Steam

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Soybean Oil Extraction - Supercritical CO 2Soybean Oil Extraction - Supercritical CO 2

SoybeanFlakes

SoybeanMeal

SoybeanOil

CO2 Makeup

Ext

ract

or

Flash

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Nucleophilic aromatic substitution process

vs.

Chlorine-based process

Project 3: Production of p-NitroanilineProject 3: Production of p-Nitroaniline

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p-Nitroaniline - Conventional Processp-Nitroaniline - Conventional Process

1. Chlorination of benzene

NO2Cl

Cl

2. Nitration of chlorobenzene

3. Ammonolysis of p-chloronitrobenzene

+ Cl2 (g)

+ HNO3 Cl

NO2Cl + 2 NH3 NO2H2N

+ HCl (g)

+ NH4Cl

+ H2O

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p-Nitroaniline - Conventional Processp-Nitroaniline - Conventional Process

Benzene

Cl2

NaOH

HCl

Saltwaste

MCB

DCB

H2SO4HNO3

Steam NaOH

Saltwaste

DCB purge

pCNB

p/oCNB wasteoCNB

NH3

Aqueous NH3 waste

pNA

H2O

NH4Clwaste

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NH2

ONO2+ + TMAOH

HN

O

NO2 + TMAOH

+ NH3

NH2

O

+

p-Nitroaniline - New Chemistr yp-Nitroaniline - New Chemistr y

benzamide nitrobenzene tetramethylammonium hydroxide dihydrate

N-(4-nitrophenyl)benzamide

p-nitroaniline benzamide

NO2H2N

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p-Nitroaniline - New Chemistryp-Nitroaniline - New Chemistry

BANBTMAOH

BA + TMAOH recycle

BA=benzamideNB=nitrobenzeneTMAOH=regenerated reagentNPB=intermediatePNA=p-nitroaniline

Reactors

Crystallizer

NBNB + NPB

NPB

NH3 Methanol Reactor

NH3 + Methanol recycle

BArecycleto feed

PNA

NPB recycle

BAPNANPB

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• Course taught at Notre Dame three times (JFB)– Spring 1997 (lecture format; seniors)– Spring 1998 (lecture format; juniors and seniors)– Fall 1999 (discussion format)

• Modified version taught at West Virginia University– Spring 2000– Professor Joseph. A. Shaeiwitz– Used materials from draft of new “Green Engineering” text

(EPA; D. Allen)

Teachin g ExperienceTeachin g Experience

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• Entry and exit questionnaires used.• No significant changes in student attitudes. Students

appreciated both before and after the course thatindustrial activity has an impact on the environment.

• Increase in student knowledge of environmentalregulations.

• Increase in student awareness of pollution preventionconcepts and technologies, from simple“housekeeping” solutions to use of entire newtechnologies.

AssessmentAssessment

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Related Work: http://www.nd.edu/~enviro

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• National Science Foundation Combined Researchand Curriculum Development Program (EEC97-00537-CRCD)

• Camille and Henry Dreyfus Foundation SpecialGrants Program

• Shell Oil Foundation

Acknowled gementsAcknowled gements