University of Limerick
OLLSCOIL LUIMNIGH
The Conceptual Design Approach – A Process Integration Approach on the Move
Theodore Zhelev*, Jiri Klemeš**
*University of Limerick, Ireland **The University of Manchester, UK
Outline
Background – process systems engineering Combined resources management Impact on Energy & Environment Emissions “planning” New challenges
Micro process integration
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Background
Process systems engineering
Optimal Design and Operation of New And Existing Industrial Processes Industrial resources management Conceptual approach
Process integration
Mathematical approach Process synthesis Superstructure approach Branch and bound NP, NLP, MINP
Combinatorial – heuristical Pinch analysis Process optimisation
Structural (topology)
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Parametrical optimisation
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The Way Forward
• Pinch success in individual industrial resources management (Thermal, Mass, Water, Flue gas, Hydrogen, Oxygen, • Development - Combined Pinch:
– Heat + time (Time Pinch for Batch); – Heat + utility (Utility Pinch); – Heat + power (Combined Heat and Power); – Heat + Water; – Heat + Mass, …
Hardware, etc.)
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or … Combined Management of Industrial Resources !
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Addressing Simultaneously Heat and Mass
Variety & Classification Limiting stage Processes limited by the mass transfer: Processes limited by the heat transfer:
extraction, particle separation (settling, sedimentation), solution, concentration, etc. boiling, condensation, drying, distillation, absorption, rectification, etc.
Question: Can we save water through saving energy?
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Management of one resource – Combined resources management – the way forward
OBJECTIVE Save both water and energy simultaneously. HYPOTHESIS “Fresh water can be saved though better management of energy”
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Operation Analysis
E n t h a l p y (Gas)
Dehumidifier
Hot composite
Flue gas Air Humidifier Air to boiler
Equilibrium curve
Pinch Cold composite
T e m p e r a t u r e (Liquid)
Composite Curves combined with equilibrium curve
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Application example
Turbines
Cooling tower Coal Boiler
HPH Condenser
LPH
Dehumidifier Air Flue gas Precipitator Humidifier
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Targeting maximum efficiency
Flue gas energy recovery Targeting: - maximum energy recovery - maximum potential of recovered heat
T T
Water cooling Targeting: - maximum cooling load - minimum cooling water temperature
H
Grand Composite Curve
for the flue gas heat recovery system
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H
Grand Composite Curve for the cooling system
(a)
(b)
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Total Site View
Economiser System
Drying unit Direct Heating
r ange h t Exc rk Hea two Ne
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g olin Co m e Syst
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Process Integration through Process Decomposition
T [°C]
100
Process composites Flue gas recovery composites Equilibrium curve
80 60
40
Pinch 2
20
Pinch 1
200 400 600 800 1000 1200
• Separate process composites • Separate Flue gas heat composites • Individual minimum temperature approach • Typical threshold problem • Grand Composite Curve – separate to address the maximum potential of recovered heat and min temperature of cooling water
H [kW]
Combined Composite Curves for a brewery
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Multiple Industrial Resources Management
Introducing Environmental Concerns
Emergy-Pinch Analysis for Integrated Energy-Waste Analysis
Emergy Analysis
Solar emergy - the solar energy necessary to obtain a product or a flux of energy in a process It is an extensive quantity – unit = [seJ] Solar transformity - the emergy necessary to obtain one unit of product. It is an intensive quantity [seJ/J]
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Emergy Features
Common unit Compares human labor, utilities, raw materials, goods, services Memory (the sum) of all energies Ability to identify critical processes Measures the real value of natural resources Gives historical information
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Combined Emergy – Pinch Analysis
Addressed by Emergy
Desig n cha nges
History
E
s ent fflu
Raw materials
Process
Desig chan n ges
Products
Addressed by Pinch analysis
Point 1 – waste & energy recovery = management Point 2 – can we go beyond evaluation/alternatives? IEA December 2006
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Application
Without heat integration Qh = 46073 KW Qc = 51660 KW
COAL GASIFICATION PROCESS
Purge Gases Reactor Water + M ethanol 64.7 M ethanol
Pipeline Gas (CH 4 , CO 2 )
Compresor Coal Gas (CO, H 2 ) 70 Flue Gas (CO 2 , H 2 O) 140 W ater Separator Heat Recovery 700 Cooler Coal 20 Coal Slurry 150 Recirculator Water + M ethanol 35 Pipeline Gas (CH 4 , CO 2 ) 70
Gasification Reactor
Pipeline Gas (CH 4 , CO 2 ) Flue Gas
700
With heat integration Qhmin = 0 KW Qcmin = 4640 KW
Flue Gas 600
W ater 1 18
Steam 140
Slag 600 Bricks 21 Bricks 355 Drying
Bricks 900 Baking Air 760
Slag 200
M ixer
Flue Gas Bricks 40 Vapour 100 Air
Pipeline Gas (CH 4 , CO 2 ) Air 20
Process design changes suggested by Pinch analysis Alternatives for products reclaim suggested by Emergy analysis
Integration at regional scale
Clare North-West Region Limerick North Tipperary
Eco-Industrial Network
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Horizontal
Integration
Energy
Water
Waste • Energy • Water • Water/effluent treatment
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Vertical
• Waste utilisation • Services (Transport, mail, IT, landfill) •…
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New challenge – integration between large factories and SMEs
Methodology for energy integration
in Eco-Industrial Network
Heat recovery between areas of integrity (SMEs)
identification of schemes of energy recovery maximum heat flow between these areas least number of interconnections between the regions
Recoverable heat Using 2 levels steam
(Ref: Ahmad&Hui 2001)
(a) Process to process heat transfer
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(b), (c) Indirect heat transfer options
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Marginal Value Analysis for multi-site application
• Analysis and decision making • Known use – utilities, site application • Marginal values
• Novel application – integration related decisionmaking & multi-site
– needs of integrated site model – marginal values of utilities, services, inventories, transport, IT, treatment, etc. – changes of marginal values as result of integration !!!
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– marginal profit (MP = ∆Profit/∆Change of str flow) – production cost (marginal cost) – product value
Energy Conservation in WWTP
Redesign of WwTPs for higher efficiency: – Process Integration Approach for analysing and targeting the minimum energy requirements of municipal wastewater treatment systems
–Methodology for analysis and evaluation of existing facilities – Targeting and showing eventual scope for energy efficiency improvements – Bottleneck identification – Support of decision making in case of alternative wastewater treatment options
– Addressing anaerobic and aerobic systems – Dynamic operation: Long-term disturbances – Possible integration of between wastewater and sludge treatment/industrial and municipal WwTPs
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Oxygen Pinch Analysis
Targeting quality and quantity
C,
ppm
C2 Cwmax
1/COD
Pin Pin ch
t ge tar
su pp ly l Su bs tra te in e
ch
C1
in M
um im
te r wa sh re f
Slope ∼ growth rate, O2 solubility, residence time, oxidation energy load
m, kg/hr
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1/D
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Modified Heat Integration Problems
• Usually: fixed temperatures of process streams • New: fixed desired direction of temperature change – Sludge to ATAD heat “as much as possible” (from 12°C max 60°C). • Process related thermal changes: – Effluent water used as absorbent heated from 12°C to ??°C to be returned and mixed with WW in the primary WW treatment heating WW to reduce thermal shock. • Model reaction efficiency as function of temperature: Goal = heat recovery + reaction efficiency improvement – Result – shortening the processing time (intensifying the bio-process and decreasing shock recovery time. Goal = heat recovery + process efficiency – Adsorption – more efficient at low temperature, i.e. Gas from secondary reactor to ammonia absorber to be cooled from 60°C to 22°C; rate 14 400 m3/h • Semi-batch process integration – increased complexity • Sludge load seasonal fluctuations – flexibility problem – new challenge
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Solutions: Design for flexibility
Sludge NH3 scrubber Mona-shell air filter
Off gas to NH3 scrubber and bio-filter before discharge
Water returned to head of works
1A
(40-55oC)
2A
(55-65oC) 4 Product Storage tanks 275 m3/tank (Central mixing)
1B
2B
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Energy sector planning
(Carbon Emissions Pinch)
CO2 planning
□ Targeting CO2 emissions □ Fuel mix □ Kyoto constraints
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Carbon Emissions Pinch
Prerequisites (×2) on both energy resource/supply side & energy demand/consumption side (see table below)
Energy Resource Hypothetical Amount Available (TJ = 1012 J)/ per annum 600,000 Emission Factor (t CO2(g) / TJ) CO2(g) Emission to be Generated (t CO2(g)) (Per Annum) 600,000 × 105 = 63 × 106 60 × 106 Energy Demand Amount Required (TJ) Per annum CO2(g) Emissions Limit (t CO2(g))/ Per annum 20 × 106 Resulting Emission Factor (t CO2(g) / TJ) 20 × 106 / 1,000,000 = 20 50
Coal
105
Region 1
1,000,000
(Crude) Oil
800,000
75
Region 2
400,000
20 × 106
(Natural) Gas “Others”
200,000
55
11 × 106
Region 3
600,000
60 × 106
100
400,000
≈0
≈0
------------
------------
------------
------------
Total Of All Resources
2,000,000
≈ 235
≈ 134 × 106
Total Of All Regions (National)
2,000,000
100 × 106
50
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Targeting
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Design guidelines
Tan and Foo (2006)
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Carbon Emissions Pinch Concluded
Energy Demand Energy Resource (‘000s TJ/Annum)
Example (Tan and Foo (2006)) Carbon Emissions Pinch Point: (1.4m TJ p.a., 37.5 mt CO2(g) p.a.) & Total Carbon Emissions: 92 mt CO2(g) p.a. (< Cap Of 100 mt CO2(g) p.a.)
Emission Factors In Brackets (t CO2(g) / TJ) R1
Coal (105)
Oil (75)
Gas (55)
“Others” (≈ 0)
Emissions Cap/Limit On Each Region (mt CO2(g)/ Annum)
Actual Emissions From Each Region (mt CO2(g)/ Annum)
0
100
200
700
20
(0 × 105) + (100 × 75) + (200 × 55) + (700 × 0) = 18.5 (OK) (0 × 105) + (300 × 75) + (0 × 55) + (100 × 0) = 22.5 (NOT OK) (200 × 105) + (400 × 75) + (0 × 55) + (0 × 0) = 51 (OK)
R2
0
300
0
100
20
R3
200
400
0
0
60
Total Of All Resources Total Of All Regions
200
800
200
800
100
92 (OK)
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NEW CHALLENGES
Micro-Total Analytical Systems (µ-TAS) New Challenge to the Chemical Engineering profession
–The classical role of the Chemical Engineer: Scaling – up –New challenging role: Scaling - down
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What is the motivation for “Micro” ?
Low design cost Low running cost Reduced waste production High speed analyses, parallel architectures, high throughput Reliable and simple to operate Easy to integrate (within existing systems) Controllable continuous process versus batch Application – forensic, DNA analysis, drug discovery, replacing batch, micro-fuel cells, etc.
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Design Implications
The reserves (overdesign) can not be used as flexibility compensation (affects the function of the device).
Shape factor plays much bigger role compare to macro. Shape optimisation can be valuable. Minimisation of transition time between unit operations Minimisation of transition time between temp. zones New types of design constraints:
Average residence time; Residence time distribution; Temperature distribution.
Difficult to measure and control flow conditions
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Current tasks
Identify typical design options Math model of a PCR Energy conservation Optimal design + campaign control
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Current tasks
Simulation tool
Collaboration with TU Giessen, Germany
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Increasing the complexity
Micro-process integration
Stack of micro-reactors for bio diesel production
Gantt chart Micro-fluidic-reactor
TASKS: Cycle time minimisation Changeover minimisation Campaign time minimisation Heat integration Etc …
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More to come soon
University of Limerick
OLLSCOIL LUIMNIGH
Visit www.conferencepres.com
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10th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction ISCHIA Island Gulf of Naples 24 - 27 June 2007 Organiser & Secretariat Italian Association of Chemical Engineering
Attn. Dr. Raffaella DAMERIO Via Giuseppe Colombo 81A20133 Milano (Italy) Tel: +39-02-70608276 Fax: +39-02-59610042 E-mail AIDIC: pres07@aidic.it E-mail PRES’07: pres07@tiscali.co.uk Website www.conferencepres.com
Deadlines
20 December 2006 Abstracts submission 20 February 2007 The second circular with preliminary program 10 May 2007 Registration for participation and payment 20 May 2007 Submission of the full text and revised Manuscript 10 June 2007 Technical Program
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www.aidic.it/pres07
IEA December 2006
10th Conference Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction ISCHIA Island Gulf of Naples 24 - 27 June 2007
IEA December 2006
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