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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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Presentation Transcript
slide1

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

slide2

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

slide3

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

T. Gundersen

E&M 03

slide4

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

T. Gundersen

E&M 04

slide5

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

T. Gundersen

E&M 05

slide6

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

T. Gundersen

E&M 06

slide7

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

T. Gundersen

E&M 07

slide8

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

T. Gundersen

E&M 08

slide9

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

T. Gundersen

E&M 09

slide10

“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

T. Gundersen

E&M 10

slide11

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

T. Gundersen

E&M 11

slide12

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

T. Gundersen

E&M 12

slide13

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

T. Gundersen

E&M 13

slide14

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

T. Gundersen

E&M 14

slide15

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

T. Gundersen

E&M 15

slide16

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

T. Gundersen

E&M 16

slide17

10%

30%

100%

20%

40%

Ref.: Olav Bolland

Basic Principle for Combined Cycle Plant

Process, Energy and System

Energy & Environment

T. Gundersen

E&M 17

slide18

Ref.: Olav Bolland

Combined Cycle Power Plant

Power Production only

Heat & Power Production

Process, Energy and System

Energy & Environment

T. Gundersen

E&M 18

slide19

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

T. Gundersen

E&M 19

slide20

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