A Course in Environmentally Conscious Chemical …markst/pse2000slides-1.pdf• Allen and Sinclair...
Transcript of A Course in Environmentally Conscious Chemical …markst/pse2000slides-1.pdf• Allen and Sinclair...
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
PSE 2000 4
• 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
PSE 2000 5
• Introduction to pollution prevention
• Environmental regulations
• New technology and current research
• Design projects: Comparison of conventional
processes with new environmentally benigntechnologies
Course ComponentsCourse Components
PSE 2000 6
• 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
PSE 2000 7
• 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
PSE 2000 8
• 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
PSE 2000 9
• 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
PSE 2000 10
• 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
PSE 2000 12
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
PSE 2000 13
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
PSE 2000 14
Extraction with supercritical CO2
vs.
Extraction with hexane
Project 2: Extraction of Soybean OilProject 2: Extraction of Soybean Oil
PSE 2000 15
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
PSE 2000 16
Soybean Oil Extraction - Supercritical CO 2Soybean Oil Extraction - Supercritical CO 2
SoybeanFlakes
SoybeanMeal
SoybeanOil
CO2 Makeup
Ext
ract
or
Flash
PSE 2000 17
Nucleophilic aromatic substitution process
vs.
Chlorine-based process
Project 3: Production of p-NitroanilineProject 3: Production of p-Nitroaniline
PSE 2000 18
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
PSE 2000 19
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
PSE 2000 20
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
PSE 2000 21
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
PSE 2000 22
• 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
PSE 2000 23
• 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