IDRIST Temporal pinch-point analysis for energy demand reduction in batch production Thorsten Spillmann
Content Introduction to IDRIST project Importance of pinch-methodology for energy demand reduction Challenges of thermal integration in batch processes Summary of approach taken Outlook IDRIST Thorsten Spillmann 2 1
IDRIST Project Phases Industrial Demand Reduction through Innovative Storage Technologies 1. Market Potential Assessment 1. Identify industry needs and market potential 2. Investigation of Integrated PCM thermal storage systems 1. Identify and characterise candidate PCMs 2. Design laboratory tests and simulation 3. Experimental evaluation & model validation 4. System modelling for industrial applications 3. Investigation of Thermo-chemical heat storage and transformation 1. Short list salt-refrigerant working pairs using ideal thermodynamics 4. Whole systems modelling 1. Business models, techno-economic assessments 2. Whole system performance modelling Poster presented at 2015 UKES Conference online at: http://i-stute.org/ IDRIST Thorsten Spillmann 2
Pinch methodology for energy demand reduction (1) Pinch Analysis is a discipline of Process Integration, which emphasises on the efficient use of energy and reducing environmental effects (IEA). Developed for heat recovery in continuous production processes, but also used in other areas (e.g. waste water minimisation, hydrogen distribution in oil refineries) Central Aspect is the identification of the point of smallest driving force for network integration Pinch Concept: Establishment of performance targets before design 4-Phase Approach: Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 3
Pinch methodology for energy demand reduction (2) Block diagram Stream data Stream ID T s ( C) T t ( C) T * s ( C) T* t ( C) MCp(kW/ C) ΔQ(kW) ΔT min ( C) Reactor Outlet H1 270 160 280 170 18 1980 20 Product H2 220 60 230 70 22 3520 Feed C1 50 210 40 200 20 3200 Recycle C2 160 210 150 200 50 2500 4-Phase Approach: Necessary stream data from energy audit: Mass flow rate Specific heat capacity Supply & Target temperatures Decision if heat integration of certain units is not desired Costly piping Start and stop times Heat of vaporisation Safety, product purity operability Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 4
Temperature ( C) Temperature ( C) Temperature ( C) 300 250 200 150 100 50 0 Pinch methodology for energy demand reduction (3) 250 200 150 100 50 0 0 2000 4000 6000 0 5000 10000 Heat Duty (kw) Heat Duty (kw) Stream data hot streams Stream ID T s ( C) T t ( C) T * s ( C) T* t ( C) MCp(kW/ C) ΔQ(kW) ΔT min ( C) Reactor Outlet H1 270 160 250 140 18 1980 20 Product H2 220 60 210 40 22 3520 Feed C1 50 210 70 230 20 3200 Recycle C2 160 210 180 230 50 2500 4-Phase Approach: cold streams 300 250 200 150 100 50 0 Composite Streams Q 0 c 2000 4000 6000 8000 Heat Duty (kw) Q h Hot Streams Cold Streams ΔTmin( C) Grand Composite Curve 300 250 200 150 100 50 0 Q h pocket Q c 0 1000 2000 Heat Duty (kw) Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 5
Temperature ( C) Pinch methodology for energy demand reduction (3) Streams are grouped together into 1000kW Q h 260 C subnetworks based on their temperatures +720 220 C 1720kW Grand Composite Curve -520 300 Q that represents the physical constraint to heat h pocket 1200kW 250 transfer and is related to heat exchanger -1200 200 surface area and costs. 170 C 0kW 150 +400 100 150 C 400kW network, where the driving force for heat 50 +180 transfer is minimal 60 C 580kW 0 Q c A minimum ΔT min for heat exchange is defined The pinch point represents the location in the 4-Phase Approach: +220 50 C 800kW Q c 0 1000 2000 Heat Duty (kw) Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 5
Pinch methodology for energy demand reduction (3) The pinch divides the network into a high temperature region, that only requires hot utility supply, and a low temperature region, that only requires cold utility. Heat transfer between the two regions results in increased utility demands. This means that subnetworks for the two regions can be designed independently from one another Pockets of the Grand Composite Curve represent internal heat transfer between subnetworks 4-Phase Approach: 1000kW 260 C +720 220 C 1720kW -520 1200kW -1200 170 C 0kW +400 150 C 400kW +180 60 C 580kW +220 50 C 800kW Q h Q c + (X + Z) AP X Z Y BP + (Y + Z) Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 5
H 1 220 C H 2 Pinch methodology for energy demand reduction (4) 270 C 180 C 190 C H 3 1000kW 620kW 3 2 1 2 1000kW 178 C C 2 880kW 160 C 4-Phase Approach: 1 80 C 4 2500kW C 160 C 360kW 60 C 4 C 440kW 50 C C 1 1000kW 260 C +720 220 C 1720kW -520 1200kW -1200 170 C 0kW +400 150 C 400kW +180 60 C 580kW +220 50 C 800kW Q h AP BP Q c Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 6
H 1 220 C H 2 Pinch methodology for energy demand reduction (5) 270 C 180 C 1000kW 3 1 3 1620kW 1 880kW C 2 4-Phase Approach: 80 C H 4 2500kW 160 C C 160 C 360kW 60 C 4 C 440kW 50 C C 1 1000kW 260 C +720 220 C 1720kW -520 1200kW -1200 170 C 0kW +400 150 C 400kW +180 60 C 580kW +220 50 C 800kW Q h AP BP Q c Data Collection Performance Targeting Design Optimisation IDRIST Thorsten Spillmann 7
Thermal integration in batch processes Process Integration becomes more complex with the time-dependence of process streams, i.e. heat transfer possibilities are now constrained not only by temperature, but also by time Heat exchange can occur direct, when processes occur at the same time, or indirect when heat is exchanged with a storage medium to be used at a later point in time Limited implementation due to lack of established methods and design tools. Approaches suggested in literature differ according to simplifying assumption made and degree of complexity Two types of thermal integration: within batches, between batches Batch 1 TES Batch 2 task 1 task 2 task 3 task 1 task 2 task 3 TES IDRIST Thorsten Spillmann 8
Approach taken (1) Division of time horizon into intervals with pseudo-continuous streams Composition of interval specific heat cascades identifying utility demand reduction through direct heat integration (within individual intervals). Composition of modified heat cascades identifying further reductions in utility requirements due to indirect heat integration (between intervals). Literature Example: Chaturvedi (2014) Name T supply T target MCp t start t stop ΔT min C1 80 140 8 0 0.5 10 H1 170 60 4 0.25 1 10 C2 20 135 10 0.5 0.7 10 H2 150 30 3 0.3 0.8 10 Initial Heat Exchange Design based on Pinch Design Method IDRIST Thorsten Spillmann 9
Hot Utility Demand (kwh) Approach taken (2) Direct Heat Transfer Divide streams into time slices Use conventional pinch methodology (PTA) to calculate utility targets Indirect Heat Transfer Modify GCC to determine thermal energy available for integration with subsequent intervals Repeat Integration Procedure for subsequent interval with shifted temperatures including pseudo hot streams = heat available from subnetworks for integration with subsequent intervals Grand Composite Curves Results for 3 example cases 250 heat transfer 200 direct within batch 150 between batches 100 50 0 IDRIST Thorsten Spillmann 10
Outlook Complete Computerised Initial Design Method Adapt targeting routine to represent different thermal store/ heat exchanger designs Utilise routine on further example cases from literature and industry IDRIST Thorsten Spillmann 11
THANK YOU! workshop 07/10/2015 IDRIST Thorsten Spillmann 18