Special Lecture on Energy & Environment
Process
Process, Energy and System
Energy
•
•
•
•
•
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Process
Integration
Environment
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
Clean Process Technology – Some Ideas
(Ref.: Robin Smith, Chemical & Process Integration, Ch. 28)
Process, Energy and System
• 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:
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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
Energy & Environment
T. Gundersen
E&M 02
Sources of Waste from the Process Industry
Process, Energy and System
R
S
H
U
R + S : Process Waste
H + U : Utility Waste
• Types of Process Waste:

Waste Byproducts, Purge Streams, etc.
• Sources of Process Waste:
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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.)
Energy & Environment
T. Gundersen
E&M 03
Sources of Waste from the Process Industry
Process, Energy and System
R
S
H
U
R + S : Process Waste
H + U : Utility Waste
• Types of Utility Waste:
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Gaseous Combustion Products (CO2, SOx, NOx, Particles)
Aqueous Waste from BFW (Boiler FeedWater) Treatment
Waste from Water Systems
• Sources of Utility Waste:
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
Hot Utilities (incl. Cogeneration)
Cold Utilities and Water Systems
Energy & Environment
T. Gundersen
E&M 04
Sources of Waste from the Process Industry
Process, Energy and System
R
S
H
U
R + S : Process Waste
H + U : Utility Waste
• 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
Process, Energy and System
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
Energy & Environment
T. Gundersen
E&M 06
Environmental Design for Atmospheric Emissions
(Ref.: Robin Smith, Chemical & Process Integration, Ch. 25)
Process, Energy and System
• 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)
Energy & Environment
T. Gundersen
E&M 07
Environmental Design for Atmospheric Emissions
(Continued)
Process, Energy and System
• Ozone Layer Destruction
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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
Energy & Environment
T. Gundersen
E&M 08
Actions that reduce the Environmental
Impacts from Energy Consumption
Process, Energy and System
• Statement: The most “Green” Energy is the
Energy that is not used
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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
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Use less Energy (vs. “Standard” of Living)
Increase Energy Efficiency
Increase Process Efficiency
Switch between Fossil Fuels
Switch from Fossil Fuels to Renewables
Energy & Environment
T. Gundersen
E&M 09
Process, Energy and System
“Energi21” − National Strategy for R&D,
Demonstration & Commercialization
− Energy in the 21st Century
• The Vision of Energi21
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Norway: Europe’s leading Energy and EnvironmentConscious Nation − from a National Energy Balance
to Green Energy Exports
• To realize this Vision: 5 Priority R&D Areas
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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
Energy & Environment
T. Gundersen
E&M 10
Energy Consumption (TWh) in Norway
by Sector in 2007 (Total: 813.5 PJ)
Process, Energy and System
Other Sectors: Private household (20.0%), Community
Consumption (13.7%) and Fishing/Agriculture (3.6%)
35.1%
37.3%
27.6%
Industry & Mining
Transportation
Other Sectors
T(erra) = 1012
 The Course “Energy & Process” makes Sense !!
Energy & Environment
T. Gundersen
E&M 11
Energy Consumption (TWh) in Norwegian
Industry in 2007 (Total: 80.66 TWh)
Process, Energy and System
Aluminum
29.6%
Chemical
Pulp & Paper
Petrochemical
Food Industry
Iron & Steel
Minerals
Wood Ware
12.0%
13.6%
17.6%
Mining
Others
Discuss: Primary Application Areas for Process Integration?
Energy & Environment
T. Gundersen
E&M 12
Main Focus in TEP 4215: Efficient Use of Energy
Process, Energy and System
• Saving Energy means Saving the Environment in
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•
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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
Energy & Environment
T. Gundersen
E&M 13
What we’ve done in TEP 4215
Process Integration
Process, Energy and System
• Heat Recovery between Hot and Cold Streams to reduce
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•
•
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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
Energy & Environment
T. Gundersen
E&M 14
Tools developed in Process Integration
Process, Energy and System
• The Composite Curves
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Provides Insight and a Graphical Way to establish
Energy Targets
Suggests Process Modifications (+/− Principle)
• The Grand Composite Curve
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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
Energy & Environment
T. Gundersen
E&M 15
A brief Discussion about Efficiencies
Process, Energy and System
• Energy vs. Exergy Efficiency
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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
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“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
Energy & Environment
T. Gundersen
E&M 16
Basic Principle for Combined Cycle Plant
10%
Ref.: Olav Bolland
Process, Energy and System
30%
100%
20%
40%
Energy & Environment
T. Gundersen
E&M 17
Combined Cycle Power Plant
Power Production only
Heat & Power Production
Process, Energy and System
P  Q 48.5  41

 89.5%
E
100
P 48.5
 
 48.5%
E 100


P 57

 57%
E 100
Ref.: Olav Bolland
Energy & Environment
T. Gundersen
E&M 18
Some Efficiency Calculations
• Exergy Content of Heat Q at Temperature T
Process, Energy and System
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
Ex = Q  (1 − T0/T)
T0 is “ambient” temperature (25°C or ≅ 298 K)
• Exergy Content of Fuel
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
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”
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Produce Electricity, “take back” the Heat later !!
Energy & Environment
T. Gundersen
E&M 19
Indicators for CO2 Emissions
• Material Production
Process, Energy and System

tons of CO2/tons of Product
• Energy Production

tons of CO2/MWh Electricity
• Consider 3 Cases of Power Production
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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
Energy & Environment
T. Gundersen
E&M 20