Summary for TEP 4215 E&P/PI T. Gundersen Reactor System (R)  Endothermic vs. Exothermic Reactions  Equilibrium vs. Kinetics  Temperature Dependence of Equilibrium Constants and Reaction Rates (Arrhenius)  Reactors play a key Role in the Thermal and the Mechanical Energy System of a Plant (or Site)  Correct Integration of Reactors Sum 1 Process, Energy and System Summary of Process Integration RSHU

Summary for TEP 4215 E&P/PI T. Gundersen Reactor / Separator Interface (R/S)  Focus of the Discussion was based on the Definition and Use of the following Terms:  Degree of Conversion (Extent of Reaction)  Selectivity  Yield (Reactor and Process)  Recycle Rate Sum 2 Process, Energy and System Summary of Process Integration RSHU Y R = X · S Y P = X · S · (1 + W) RSFR P PXPX RXRX RFRF BPBP

Summary for TEP 4215 E&P/PI T. Gundersen Separation System (S)  Economical Trade-offs in Distillation Columns  Operating Cost vs. Investment Cost  Number of Stages, Reflux and Pressure  Combinatorial Issues & Heuristic Rules related to the Sequence of Distillation Columns  Heat Integration Opportunities between Columns (Condenser / Reboiler)  Briefly about Evaporators  Multi-effect, Forward/Backward Feed, BPR Sum 3 Process, Energy and System Summary of Process Integration RSHU

T. Gundersen Sequence of Distillation Columns Sum 4 Separation Systems Process, Energy and System Problem Definition by Thompson and King, AIChE Jl, 1972: ”Given a mixture of N chemical components that is to be separated into N pure component products by using a selection of M separation methods”

T. Gundersen Sequence of Columns Sum 5 Separation Systems Process, Energy and System ABCDABCD ABCDABCD ABCDABCD ABCDABCD BCDBCD BCDBCD ABCABC ABCABC CDCD BCBC CDCD BCBC ABAB ABAB 2 comps.  1 sequence 3 comps.  2 sequences 4 comps.  2x(1+3 comps.) + 1x(2+2 comps.)  2x2 + 1 = 5 sequences 5 comps.  2x(1+4 comps.) + 2x(2+3 comps.)  2x5 + 2x2 = 14 sequences 6 comps.  2x(1+5 comps.) + 2x(2+4 comps.) + 1x(3+3 comps.)  2x14 + 2x5 + 2x2 = 42 sequences

T. Gundersen Sequence of Distillation Columns Selected Heuristic Rules Sum 6 Separation Systems Process, Energy and System H1:Favor Separation of the most Volatile Component H2:Favor near-Equimolar Separation H3:Favor Separation of the most Plentiful Component H4:Favor Simple Separations > Heuristics cause Conflicts, some can be Quantified, others just ”cast a vote”, their main use is to Eliminate Sequences !!

T. Gundersen Example – Distillation Sequence Separation Systems Process, Energy and System Comp. NameMole Frac.α=Ki/Kj”CES” APropane Bi-Butane Cn-Butane Di-Pentane En-Pentane0.35 Nadgir & Liu, AIChE Journal, 1983: f = min (D/B, B/D) Δ = (α – 1)  100 CES = f  α Sum 7

Summary for TEP 4215 E&P/PI T. Gundersen Heat Recovery System (H)  Targets for best Performance  Minimum Energy from the Heat Cascade  Minimum Energy Cost with Multiple Utilities from the Grand Composite Curve  Fewest Number of Units from the (N – 1) Rule  Minimum Area from Spaghetti Design (“Bath”)  Total Annual Cost vs. ΔT min  3-Way Trade-off (Area, Energy and Units) Sum 8 Process, Energy and System Summary of Process Integration RSHU

T. GundersenSum 9 Process, Energy and System Summary of Process Integration Heat Cascade as Algorithm/Procedure (1) (0)Given Set of Hot Stream Temperatures: TH, i = 1,n H, Set of Cold Stream Temperatures: TC, j = 1,n C, and Set of mCps, i = 1,n H, j = 1,n C (1)Calculate Shadow Temperatures from Hot Streams: THS, T H,S =T H −ΔT min (2)Calculate Shadow Temperatures from Cold Streams: TCS, T C,S =T C +ΔT min (3)Obtain Total Set of Hot Stream Temperatures, THT, by merging and sorting TH and TCS  Notice that dim (THT) = n H + n C (4)Obtain Total Set of Cold Stream Temperatures, TCT, by merging and sorting TC and THS  Notice that dim (TCT) = n C + n H (5)Remove possible Duplicates in THT and TCT. The number of Temperature Intervals is then K = dim (THT) − 1 (6)Temperature Intervals are now obtained by using one Temperature from THT and one from TCT starting at the highest Temperatures (7)Identify Heat Flows from all the Hot Streams to the respective Temperature Intervals based on mCp values and Interval Temperatures

T. GundersenSum 10 Process, Energy and System Summary of Process Integration Heat Cascade as Algorithm/Procedure (2) (8)Identify Heat Flows from the respective Temperature Intervals to all the Cold Streams based on mCp values and Interval Temperatures (9)Calculate the Enthalpy (Heat) Balance (Surplus or Deficit) for each Temperature Interval (10)Cascade Heat from the first Interval to the second, and from the second to the third Interval. Continue to the end of the Cascade (11)If all Residuals (i.e. Heat from one Interval to the next) are non-negative (R k ≥ 0), then no External Heating is required, Q H,min = 0, and Minimum External Cooling is obtained as the Residual from the last Interval, i.e. Q C,min = R K (12)If at least one Residual is negative, then Minimum External Heating and Cooling are: Q H,min = − min ( R k ), k = 1,K-1, Q C,min = R K + Q H,min (13)The Process Pinch is the Interval Temperature with the most negative Residual which has zero heat flow after adding Minimum External Heating to the Cascade

T. GundersenSum 11 Process, Energy and System Summary of Process Integration Example: Stream Data from Assignment 3 StreamT s (°C) T t (°C) mCp (kW/°C) ΔH (kW) H H C C ΔT min = 10°C THT = 170, 150, 145, 90, 60, 30 TCT = 160, 140, 135, 80, 50, 20 K = 6 – 1 = 5

T. GundersenSum 12 Process, Energy and System Summary of Process Integration Example: Stream Data from Assignment 3 90°C 80°C C1 C2 H2 H1 60 kW 15 kW 170°C 160°C 150°C 140°C 145°C 135°C 60°C 50°C 30°C 20°C 7.5 kW 165 kW 82.5 kW 45 kW 90 kW 45 kW 20 kW 220 kW 110 kW 60 kW + 60 R 1 =60 R 4 =55 R 5 =40 R 2 =62.5 R 3 =−20

T. Gundersen Process, Energy and System Investment Cost WS-8 cont. Vertical Design: 2 − 3 and 1 − 4 Criss-Cross Design: 2 − 4 and 1 − T(°C) Q(kW) Explanation: Optimal Distribution of (U  T) - not only ΔT Sum 13

Summary for TEP 4215 E&P/PI T. Gundersen Heat Recovery System (H)  Design of Network using PDM  Decomposition at Pinch (Process and Utility Pinch)  Start the Design at the Pinch  Pinch Exchangers and Requirements  mCp Rules: mCp out ≥ mCp in  Population: n out ≥ n in  Focus on ΔT, not ΔH  Tick-off Rule  Check Design against Targets !! Sum 14 Process, Energy and System Summary of Process Integration RSHU

Summary for TEP 4215 E&P/PI T. Gundersen Heat Recovery System (H)  Optimization of Heat Exchanger Networks  Stream Splitting (start with: α/β = mCp 1 /mCp 2 )  Heat Load Loops and Paths  The HEN Design Process as a “Flow Diagram”  Retrofit Design of Heat Exchanger Networks  Targeting for good value of HRAT  XP Analysis (QP = QP P + QP H + QP C )  Shifting to reduce XP Heat Transfer  UA Analysis (existing and new) followed by Loops and Paths for maximum Reuse of existing Units Sum 15 Process, Energy and System Summary of Process Integration RSHU

T. GundersenSum 16 Process, Energy and System Summary of Process Integration Exam 2 June 2008 – Retrofit (60%) mCp = 60 kW/°C mCp = 50 kW/°C mCp = 40 kW/°C mCp = 20 kW/°C mCp = 80 kW/°C ΔT min = 10°C

T. GundersenSum 17 Process, Energy and System Summary of Process Integration Exam 2008 Simplified Cascade with Supply Temperatures only

T. GundersenSum 18 Process, Energy and System Summary of Process Integration Exam 2008 Cross-Pinch Analysis H1H2 Cb C1 180° 77.5° 200° 105° 130° ° 60° 40° 70° 50° mCp (kW/°C) [60] [40] [20] [50] I C3 II I III 110° 100° 190° 100°[80] II C2 Ca H III 145° 110°

T. GundersenSum 19 Process, Energy and System Summary of Process Integration Exam 2008 y can be found by ΔT min requirements  y = 1500 kW Next: What about Investments ?? H1 180° 200° 130° ° 60° 50° mCp (kW/°C) [60] [50] I C3 I 190° 145° [80] IV C2 Ca H y 3600-y 4300-y IV “Shifting” T H1

T. GundersenSum 20 Process, Energy and System Summary of Process Integration Exam 2008 Next: UA Analysis for maximum Reuse of existing Exchangers H1 H2 Cb C1 180° 77.5° 200° 105° 130° 96.67° 60° 40° 70° 50° mCp (kW/°C) [60] [40] [20] [50] I C3 II I III 190° 100° [80] II C2 Ca H III 145° 110° IV ° °

Summary for TEP 4215 PI T. Gundersen Separation/Heat Recovery Interface (S/H)  Columns integrated above/below Pinch  Condenser above, Reboiler below  Which Pinch – Columns often create Pinch  Extended Grand Composite Curve (Andrecovich)  Distinguish Columns from “Background” Process  Evaporators and Heat Integration  The Tool is again the Grand Composite Curve  Play with Pressure and the Number of Effects Sum 21 Process, Energy and System Summary of Process Integration RSHU

Summary for TEP 4215 PI T. Gundersen Heat Recovery / Utility Interface (H/U)  Correct Integration of Heat Pumps (open/closed)  Correct Integration of Turbines (back pressure or extraction vs. condensing turbines)  Co-production of Heat & Power (cogeneration)  The quantitative Tool with Information about Load (heat duty) and Level (temperature) is:  The Grand Composite Curve  Modified Temperatures are important !! Sum 22 Process, Energy and System Summary of Process Integration RSHU

Summary for TEP 4215 PI T. Gundersen Utility System (U)  Not treated in much Detail in this Course  Topics could (or should?) have been:  Design of Steam Systems (turbines, boilers, deaerators, etc.)  Design of fired Heaters (Furnaces) with optimal preheat of Combustion Air  Design of Refrigeration Cycles including Integration with the Process (“economizers”)  Etc., etc. Sum 23 Process, Energy and System Summary of Process Integration RSHU

Summary for TEP 4215 PI T. Gundersen Other Topics  Optimization: Only Demo with Examples from Heat Recovery using Math Programming  Forbidden Matches & Extended Cascade is relevant  Operational Aspects (especially related to Flexibility and Controllability)  The Importance of Topology (Structure)  Extensions of the Pinch Principle  Heat Pinch, Mass Pinch, Water Pinch and Hydrogen Pinch (whenever an “amount” has a “quality”) Sum 24 Process, Energy and System Summary of Process Integration RSHU

More on the Grand Composite Curve Reactor Feed Product Distillation Column Compressor 50° 210° 160° 210° 130° 220° 160° 270° 60° Reboiler Condenser T. Gundersen Heat Integration − Introduction Process, Energy and System Extra 01 H1 H2 C1 C2

Grand Composite Curve is based on the Heat Cascade T. GundersenExtra 02 Process, Energy and System Heat Integration − Targeting 270ºC ºC 230ºC ºC 220ºC ºC 180ºC ºC 160ºC ºC 70ºC ºC H1 H2 CW C1 C2 ST 720 kW 180 kW 720 kW 880 kW 440 kW 1980 kW 500 kW 200 kW 800 kW 1800 kW kW 400 kW ºC ºC 360 kW 220 kW ΔT min = 20°C The necessary data are modified Temperatures and the corresponding Heat Flows

T 6 ’ = 50 Q C,min = 800 CW ST T 0 ’ = 260 Q H,min = 1000 T 1 ’ = 220 R 1 = 1720 T 2 ’ = 210 R 2 = 1200 T 3 ’ = 170 R 3 = 0 T 4 ’ = 150 R 4 = 400 T 5 ’ = 60 R 5 = 580 Grand Composite Curve (or Heat Surplus Diagram) T. GundersenExtra 03 Process, Energy and System Heat Integration − Targeting Q (kW) MP HP 0 LP CW T' (°C) Question: Is this another Pinch?

T 6 ’ = 50 Q C,min = 800 CW ST T 0 ’ = 260 Q H,min = 1000 T 1 ’ = 220 R 1 = 1720 T 2 ’ = 210 R 2 = 1200 T 3 ’ = 170 R 3 = 0 T 4 ’ = 150 R 4 = 400 T 5 ’ = 60 R 5 = 580 Grand Composite Curve T. GundersenExtra 04 Process, Energy and System Heat Integration − Targeting Q (kW) MP HP 0 LP CW T' (°C) Answer: No

“New” CCs based on Heat Surplus and Deficit Part of Gr.CC and balanced by Hot and Cold Utilities (not representative for Area demand) T. GundersenExtra 05 Process, Energy and System Heat Integration − Targeting PP UP CW MP HP LP T(°C) Q(kW) Another way of showing it is not another Process Pinch

True Balanced Composite Curves with Utilities (Notice difference in shape and scale) T. GundersenExtra 06 Process, Energy and System Heat Integration − Targeting T(°C) Q(kW) UP PP UP