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Engineering: Classroom vs. Real Life

• Classroom problems: one correct answer– Designed to stress concepts and execution– The majority of problems in this course

• Real Life: open ended problems, with more than a single solutione.g. An ore contains a valuable chemical. Develop an economical,

safe, environmentally sound process to extract the chemical with a purity of at least 87 weight percent.

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Application of M&E Balances:Life Cycle Analysis

• Systematic approach for examining and comparing the impacts of processes.

• Often used as Management Tool for Strategic Planning.

• Considers impacts on the environment and economics among others.

• An effective tool in Pollution Prevention (part of Canada’s Greening of Government principles).

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Historical Perspective• In past, many chemical processes were created in a beaker,

and scaled with little regard to impact on energy or materials.

• If environmental considerations made, they were only concerned with the manufacturing process.

Life Cycle Analysis (LCA)• LCA moves beyond the boundaries of the factory,

considering issues from the procurement of raw materials through their disposal.

• Definition of system boundaries usually affects the analysis results.

• Often called Cradle-to-Grave analysis.

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Expanding System Boundaries

M&E Balances can be performed on each of the product life stages

CHEE 221

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LCA typically focuses on products, not processes

Recycling / reuse of materials can have a significant impact on LCA findings

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Product Life Stages

Premanufacture – acquisition of materials and parts, including transportation.

Manufacture – processing, assembly, finishing and transport.

Packaging and Distribution – everything between manufacture and the consumer.

Use and Maintenance – from the time the consumer receives item to disposal.

End of Life – recycle, remanufacture, incineration or landfill.

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LCA Flow Diagrams

• A flow sheet can be easily made from one stage to another.• More complicated flow sheets can be created describing activities in

each of the life stages. • The entire life of the object is considered, not just the manufacturing

step.

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LCA Subsystems: Manufacturing

• focus of typical problems in F&R• ancillary materials can include those used in construction of

process, packaging of output, etc…

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LCA Subsystems: Raw Materials Acquisition

• renewable vs. non-renewable raw materials (negative “accumulation” of oil reserves)

• Often involves the harshest environmental impacts (irrigation for cotton growing destroyed the Aral Sea in the former USSR)

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LCA Subsystems: Transportation & Distribution

• Quite often ignored• An impetus for “buy local”

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LCA Subsystems: Consumer Use and Disposal

• Lifetime of product (disposable vs. reusable vs. recyclable)

• Maintenance costs of product

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Components of LCA• As this task can be complex

and detail-oriented, a methodology is followed:– Inventory Analysis –

develop catalogue of environmental impacts.

– Impact Assessment –determine impact’s severity on environment.

– Improvement Analysis –identify strategies to reduce impacts.

• Process involves “Hard” science (performing mass and energy balances to identify energy costs and waste production) and “soft” science (judgment required regarding relative weighting of environmental impact)

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Diaper ExampleBackground• Many landfills began reaching capacity in the 1980s, about

the same time LCA was being developed.• Disposable diapers were the mainstream choice of many

caregivers (why?)• Many felt cloth diapers were the more environmentally

responsible choice (why?)

Inventory Analysis• Begin with base case: cloth diapers laundered at home,

develop process flow diagrams.• Continue with alternatives: cloth diapers laundered by a

service, and disposable diapers.

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Inventory Analysis: Diapers Laundered at Home

Diapering

Diaper RetailDistribution

CottonGrowing

Landfill Municipal WasteTreatment

Energy

Energy

Energy

Energy

Washing Energy

NutrientsWater

Water

Water

Air EmissionsWater Emissions

Air EmissionsWater Emissions

Air Emissions

Water Emissions

DiaperProduction

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Inventory Analysis: Diapers Laundered by Service

Diapering

Diaper RetailDistribution

CottonGrowing

Landfill Municipal WasteTreatment

Energy

Energy

Energy

Energy

NutrientsWater

Water

Air EmissionsWater Emissions

Air EmissionsWater Emissions

Air Emissions

Water Emissions

DiaperProduction

WashingTransportationto Facility

Energy EnergyAirEmissions

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Inventory Analysis: Disposable Diapers Diapering

DiaperProduction

DiaperDistribution

PetroleumProduction

Landfill

Energy

Energy

Energy

Water

Water

Air emissions

Water emissions

Air emissions

Water emissions

Air emissions

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Diaper Example:Impact Analysis

Cloth Diapers

ImpactHome

LaunderingCommercial Laundering

Disposable Diapers

Energy 1 0.55 0.5Solid Waste 1 1 4.1

Air Emissions 1 0.47 0.48

Water Emissions 1 0.95 0.14

Water Required 1 1.3 0.27

• Impact of inventory identified in previous step is evaluated, one case at a time.

• Can be difficult to quantify completely, often estimates are made in comparison to the base case.

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Diaper Example: Improvement Analysis

• Greatest problem with cloth diapers…Potential Solutions

• Greatest problem with disposable diapers…Potential Solutions

From a study by the UK Environment Agency:• The most significant environmental impacts for the three uses of nappies were

using up resources such as fossil fuels for electricity, acid rain, and global warming. These impacts happen at different points during a nappy’s use.

– for disposable nappies, the main impacts relate to manufacturing including raw material production and waste management

– for home use reusables and commercial laundering, the main source of environmental impact is from generating the electricity used in washing and drying

• Final recommendation: “We believe that people should be free to choose whatever nappy suits them. Neither type of nappy is better or worse for the environment.”

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Limitations and Challenges

• Data is usually insufficient to calculate the damage to ecosystems by an impact.

• Even if the damage to the ecosystems could be calculated accurately, there is no generally accepted way of assessing the value of the damage to ecosystems.

• Proper LCA is expensive to perform, requiring many man-hours. Often when the LCA scope is reduced due to cost constraints, some aspects that have serious environmental consequences are neglected.

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Applications of LCA(Is it really used?)

• Germany pioneered LCA. All products priced on “cradle-to-grave”, disposal costs are bore by the consumer product company.

• EU is moving to this type of regulation.• ISO 14000 (International Standards Organization)• Part of Canada’s “Greening of Government”

philosophy.• Used by companies as part of policy planning.

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BASF (Germany): an example of integrated material and energy flows

• Excess heat and incineration of production waste provide about 55 percent of BASF’s steam requirements

• Since the mid 1970’s use of fossil energy sources for electrical power and steam generation has fallen by about 49 % at the Ludwigshafen site. During the same period, production has risen by approximately 45%

Ludwigshafen site has over 30,000 employees

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Calculated savings (by BASF) comparing integrated site costs to a structure with 70 smaller plants located 100 km apart.

– Logistics savings are from transportation and storage/handling– Infrastructure savings are from fire department, emergency medical

services, catering and wastewater treatment facilities

M&E Integration between Industries

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Kalundborg (Denmark) Eco-industrial Park

http://en.wikipedia.org/wiki/Kalundborg_Eco-industrial_Park

M&E Integration between Industries

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Kalundborg Eco-industrial Park

http://en.wikipedia.org/wiki/Kalundborg_Eco-industrial_Park

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GREEN ENGINEERING: An Operational Framework for Engineers

(from Chem.&Eng. News, 81(29), July 21 2003, pp. 30-32)

This preamble was prepared during the multidisciplinary engineering conference “Green Engineering: Defining the Principles.”

Green engineering transforms existing engineering disciplines andpractices to those that promote sustainability. Green engineeringincorporates the development and implementation of technologicallyand economically viable products, processes, and systems to promotehuman welfare while protecting human health and elevating theprotection of the biosphere as a criterion in engineering solutions.

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The 12 Principles of Green EngineeringP. A. Anastas and J. B. Zimmerman, Envir. Sc. Tech., 2003

1. Designers need to strive to ensure that all material and energy inputs and outputs are as inherently nonhazardous as possible.

2. It is better to prevent waste than to treat or clean up waste after it is formed.

3. Separation and purification operations should be designed to minimize energy consumption and materials use.

4. Products, processes, and systems should be designed to maximize mass, energy, space, and time efficiency.

5. Products, processes, and systems should be “output pulled” rather than “input pushed” through the use of energy and materials.

6. Embedded entropy and complexity must be viewed as aninvestment when making design choices on recycle, reuse, or beneficial disposition.

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The 12 Principles of Green Engineering (contd…)

7. Targeted durability, not immortality, should be a design goal.

8. Design for unnecessary capacity or capability (e.g., “one size fits all”) solutions should be considered a design flaw.

9. Material diversity in multicomponent products should beminimized to promote disassembly and value retention.

10. Design of products, processes, and systems must include integration and interconnectivity with available energy and materials flows.

11. Products, processes, and systems should be designed for performance in a commercial “afterlife”.

12. Material and energy inputs should be renewable rather than depleting.

SUMMARY SUGGESTIONS FOR CHEE 2211. Know the basics: unit conversions, mass/moles, STP, psig, Rankine to Kelvin, volumetric flow conversions, oxygen is 21% of air, etc.2. Draw and label PFDs (what is in each stream), organize your information, provide as much information for yourself as possible on the PFD (mass/mole, T, P, phase) and figure out what the process is doing.3. Read F&R, and use F&R Appendices easily. Know how to interpolate.4. Know your definitions, e.g. fractional conversion, yield, selectivity, degrees of superheat, etc.5. Determine what “type” of problem you have, and use our standard methodology to approach it. For multiple unit MB problems use DFA; for MBs with rxn use E-method or Atom Balance, for EBs with rxn, use Heat of Reaction or Heat of Formation Method. You must indicate your reference states.6. There will be no “curve balls” on the exam, just problems similar to those that you have seen in lectures and in F&R. Practice!7. Read the Cover Page of the exam and understand what additional information has been provided to you (e.g. F&R tables)8. If a question is worth 30 marks, you need to spend 30 marks worth of time on it. Budget your time. If you have time, check your algebra and signs carefully, clearly indicate all reference states, solution method, and highlight your final answer.