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Special Lecture on Energy & Environment. Process. Process Integration. Energy. Environment. Process, Energy and System. Clean Process Technology (Ch. 28 in R. Smith) Classes of Waste (Process & Utility) Environmental Impacts from Energy Usage

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T gundersen

Special Lecture on Energy & Environment

Process

Process

Integration

Energy

Environment

Process, Energy and System

  • Clean Process Technology (Ch. 28 in R. Smith)

  • Classes of Waste (Process & Utility)

  • Environmental Impacts from Energy Usage

  • Energy/Exergy & Component/System Efficiencies

  • Actions to mitigate Greenhouse Effects (Energy21)

  • How can TEP4215 Energy & Process (PI) Contribute

Energy & Environment

T. Gundersen

E&M 01


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Clean Process Technology – Some Ideas

(Ref.: Robin Smith, Chemical & Process Integration, Ch. 28)

  • Environmental Issues (similar to Heat Integration) are often considered late in the Design Process

  • The Result is often “End-of-Pipe” Solutions

  • Clean Process Technology represents an Opposite Approach similar to Process Integration thinking: Minimize Waste at Source−Examples:

    • Choose Reactions Paths that avoid harmful Chemicals being produced as byproducts

    • Keep harmful Chemicals “inside the loop” by combining producing and consuming Reactions

    • Closing Processes as in Pulp & Paper

Process, Energy and System

Energy & Environment

T. Gundersen

E&M 02


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S

H

U

R

Sources of Waste from the Process Industry

R + S : Process Waste

H + U : Utility Waste

  • Types of Process Waste:

    • Waste Byproducts, Purge Streams, etc.

  • Sources of Process Waste:

    • Reactors (byproducts, used catalysts, etc.)

    • Separation & Recycle Systems (inadequate recovery and recycle of valuable materials)

    • Process Operations (start-up, shutdown, product changeover, equipment cleaning, etc.)

Process, Energy and System

Energy & Environment

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E&M 03


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S

H

U

R

Sources of Waste from the Process Industry

R + S : Process Waste

H + U : Utility Waste

Process, Energy and System

  • Types of Utility Waste:

    • Gaseous Combustion Products (CO2, SOx, NOx, Particles)

    • Aqueous Waste from BFW (Boiler FeedWater) Treatment

    • Waste from Water Systems

  • Sources of Utility Waste:

    • Hot Utilities (incl. Cogeneration)

    • Cold Utilities and Water Systems

Energy & Environment

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E&M 04


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S

H

U

R

Sources of Waste from the Process Industry

R + S : Process Waste

H + U : Utility Waste

Process, Energy and System

  • Our Focus in these Lectures:

    • Environmental Impacts from Energy Consumption

  • Remember to take a Systems Approach:

    • Local Emissions vs. Global Emissions

    • Producing or importing Electricity?

Energy & Environment

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E&M 05


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Environmental Impacts from Processes

including their Use of Energy

  • Various Kinds of Waste Material

  • Heavy Metals

  • CO and CO2

  • NOx and SOx

  • CH4 , NH3 and other volatile compounds

  • Particles (“Particulates”)

  • VOC (Volatile Organic Compounds)

  • Heat (or Cooling)

  • Wastewater

  • Using scarce Freshwater Resources

Process, Energy and System

Energy & Environment

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E&M 06


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Environmental Design for Atmospheric Emissions

(Ref.: Robin Smith, Chemical & Process Integration, Ch. 25)

  • Urban Smog (Los Angeles, Mexico City, Lima, Shanghai)

    • Photochemical Reactions

    • VOCs + NOx + O2O3 (Ozone) + Other Photochemical Pollutants (Aldehydes, Peroxynitrates, etc.)

  • Acid Rain

    • Natural Precipitation is slightly acidic with pH around 5-6

      • Carbonic acid from dissolved CO2

      • Sulfuric acids from natural emissions of SOx and H2S

    • Human Activity can reduce pH to 2-4

      • Mainly caused by emissions of SOx

      • This is a primarily a local environmental problem

      • Can be a regional problem (from UK to Norway)

Process, Energy and System

Energy & Environment

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E&M 07


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Environmental Design for Atmospheric Emissions

(Continued)

  • Ozone Layer Destruction

    • Lower Levels of the Atmosphere: Ozone is harmful!

    • Upper Levels: Ozone essential; it absorbs ultraviolet light!

    • Destruction is due to Oxides of Nitrogen and Halocarbons

  • The Greenhouse Effect

    • CO2 , CH4 and H2O present in low conc. in the atmosphere

      • Reduces emissivity and reflects some of the heat radiated by Earth.

      • Keeps the Earth warmer −a prerequisite for Life as we know it

    • This Balance can be disturbed Global Warming

      • Burning Fossil Fuels (increased emission of CO2)

      • Large Scale harvest of Forests (reduced absorption of CO2)

  • The largest Volume of Atmospheric Emissions from Process Plants is due to Combustion

Process, Energy and System

Energy & Environment

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E&M 08


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Actions that reduce the Environmental Impacts from Energy Consumption

  • Statement: The most “Green” Energy is the Energy that is not used

    • Process Integration increases Energy Efficiency and results in Energy (in various forms) not being used

    • Investment in Equipment may cause use of Fossil Fuel based Energy elsewhere (considering LCA)

  • More comprehensive List of Actions

    • Use less Energy (vs. “Standard” of Living)

    • Increase Energy Efficiency

    • Increase Process Efficiency

    • Switch between Fossil Fuels

    • Switch from Fossil Fuels to Renewables

Process, Energy and System

Energy & Environment

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E&M 09


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“Energi21” −National Strategy for R&D, Demonstration & Commercialization

− Energy in the 21st Century

  • The Vision of Energi21

    • Norway: Europe’s leading Energy and Environment-Conscious Nation −from a National Energy Balance to Green Energy Exports

  • To realize this Vision: 5 Priority R&D Areas

    • Efficient Use of Energy (Industry/Transport/Buildings)

    • Climate-friendly Power

    • CO2-neutral Heating

    • An Energy System to meet the Needs of the Future

    • Desirable Framework Conditions for R&D

Process, Energy and System

Energy & Environment

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E&M 10


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Energy Consumption (TWh) in Norway by Sector in 2007 (Total: 813.5 PJ)

Other Sectors: Private household (20.0%), Community

Consumption (13.7%) and Fishing/Agriculture (3.6%)

Process, Energy and System

35.1%

37.3%

27.6%

T(erra) = 1012

The Course “Energy & Process” makes Sense !!

Energy & Environment

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E&M 11


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Energy Consumption (TWh) in Norwegian Industry in 2007 (Total: 80.66 TWh)

29.6%

Process, Energy and System

12.0%

17.6%

13.6%

Discuss: Primary Application Areas for Process Integration?

Energy & Environment

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E&M 12


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Main Focus in TEP 4215: Efficient Use of Energy

  • Saving Energy means Saving the Environment in one or more Ways (CO2, SOx, NOx, Particulates)

  • Process Integration provides Methods and Tools to improve Heat Recovery and Heat Integration

  • The Result is reduced Energy Consumption

  • With the current Energy Mix this also means reduced Emissions from Fossil Fuels

  • The Systems Approach in Process Integration can be used also to reduce Waste and other Impacts from the Process Industries

Process, Energy and System

Energy & Environment

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E&M 13


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What we’ve done in TEP 4215

Process Integration

  • Heat Recovery between Hot and Cold Streams to reduce Energy Consumption in the form of Hot and Cold Utilities

  • Heat Integration of Distillation Columns and Evaporators with the “Background Process”

  • Use of Heat Pumps to “lift” Thermal Energy (Heat) from below to above the Pinch by using Mechanical Energy (Power or Electricity)

  • Combined Heat and Power (Cogeneration) by using Backpressure Turbines and deliver Heat to the Process or District Heating System while producing Power/Electricity

  • Process Modifications to improve Scope for Heat Recovery guided by the “Plus/Minus” Principle

Process, Energy and System

Energy & Environment

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E&M 14


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Tools developed in Process Integration

  • The Composite Curves

    • Provides Insight and a Graphical Way to establish Energy Targets

    • Suggests Process Modifications (+/−Principle)

  • The Grand Composite Curve

    • Based on the Heat Cascade −a Transshipment Model

    • Optimal Mix of Utilities (including Production)

    • Possible Integration of Reactors

    • Integration of Distillation Columns and Evaporators

    • Potential for and Correct Use of Heat Pumps

    • Combined Heat and Power Considerations

Process, Energy and System

Energy & Environment

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E&M 15


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A brief Discussion about Efficiencies

  • Energy vs. Exergy Efficiency

    • Exergy is defined as the Ability to produce Work

    • Exergy screens Energy Types w.r.t. Quality

    • Exergy does not reflect Cost −or better: The Cost of various Energy Forms does not reflect the 2nd Law

  • Component vs. System Efficiency

    • “Local” vs. “Global” Considerations

    • Importing Electricity may improve Plant Efficiency and Emission Figures (inside Battery Limits)

    • With Process Integration, Systems Thinking and utilizing Synergies, Component Efficiencies become less Important and System Efficiency improves

Process, Energy and System

Energy & Environment

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E&M 16


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10%

30%

100%

20%

40%

Ref.: Olav Bolland

Basic Principle for Combined Cycle Plant

Process, Energy and System

Energy & Environment

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E&M 17


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Ref.: Olav Bolland

Combined Cycle Power Plant

Power Production only

Heat & Power Production

Process, Energy and System

Energy & Environment

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E&M 18


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Some Efficiency Calculations

  • Exergy Content of Heat Q at Temperature T

    • Ex = Q (1 − T0/T)

    • T0 is “ambient” temperature (25°C or ≅298 K)

  • Exergy Content of Fuel

    • Includes Chemical Exergy −Difficult !!

    • Often taken to be the Low Heating Value (LHV)

    • More pragmatic: Pure (100%) Exergy

  • Exergy Content of Power & Electricity

    • This is Pure Exergy !!

  • Calculations on the Blackboard

  • The Heat Pump “Congregation”

    • Produce Electricity, “take back” the Heat later !!

Process, Energy and System

Energy & Environment

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E&M 19


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Indicators for CO2 Emissions

  • Material Production

    • tons of CO2/tons of Product

  • Energy Production

    • tons of CO2/MWh Electricity

  • Consider 3 Cases of Power Production

    • Natural Gas (assume pure CH4) based Combined Cycle Power Plant with an Efficiency of 60%

    • Same as above but Cogeneration of Heat and Power with a Total Efficiency of 90%

    • State of the art Coal (assume C/H=1) based Power Plant with an Efficiency of 40%

  • Calculations on the Blackboard

  • Fuel Switching can be Powerful

Process, Energy and System

Energy & Environment

T. Gundersen

E&M 20


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