Correct Integration Applications: Process, Energy and System Heat - PowerPoint PPT Presentation

Correct Integration • Applications: Process, Energy and System § Heat Exchanger Networks (done !) § Distillation Columns (and Evaporators) § Heat Engines (such as Steam Turbines) § Heat Pumps (both “closed” and “open”) • Qualitative Approach: § Based on Pinch Decomposition • Quantitative Approach: § Using the Grand Composite Curve Correct Integration T. Gundersen Integration 1

Correct Integration of Distillation Columns Process Distillation Q H,min Q Reboiler Cascade Column - Q Condenser Process, Energy and System Q H,min Q Reboiler Above Above Pinch Pinch Q Condenser Q = 0 Q = 0 Savings from Integration: Below Below Q Condenser Pinch Pinch Q Condenser in External Heating Q C,min Q C,min and Cooling Correct Integration T. Gundersen Integration 2

Correct Integration of Distillation Columns Q H,min Q R1 Above Pinch - Q C1 + Q R2 Process, Energy and System  Correct !! (Saving Q cond ) Q C1 Above Pinch Across Pinch Q R2  Incorrect !! Q = 0 (No Savings) Q C2 Below Pinch Q R3 Below Pinch  Correct !! Q C,min (Saving Q reb ) - Q R3 + Q C2 Q C3 Correct Integration T. Gundersen Integration 3

Correct Integration of Distillation Columns Q H,min - Q C1 Q R1 Process, Energy and System Correct Integration R i ' = R i − Q C 1 ≥ 0 but Q C1 How much Heat can be correctly integrated ?? Q = 0 Heat Cascade Below provides the Pinch answer Q C,min Correct Integration T. Gundersen Integration 4

Correct Integration of Steam Turbines Process Steam Q H,min Q 1 Cascade Turbine - Q 2 Process, Energy and System Q H,min W Q 1 Above Above Q 2 Pinch Pinch W Q = 0 Q = 0 Q 1 – Q 2 = W Thermal Energy Below Below (Heat) converted Q 2 Pinch Pinch to Mechanical Energy (Power) Q C,min Q C,min on 1:1 Basis !! Correct Integration T. Gundersen Integration 5

Correct Integration of Steam Turbines Q H,min Q 1 Above Pinch - Q 2 + Q 3 Process, Energy and System  Correct !! W a (”backpressure”) Q 2 Above Pinch Across Pinch Q 3 W b  Incorrect !! Q = 0 (No Savings) Q 4 Below Pinch Q 5 Below Pinch W c  Correct !! Q C,min (but practical?) - Q 5 + Q 4 Q 6 Correct Integration T. Gundersen Integration 6

Correct Integration of Heat Pumps Q H,min a) Above Pinch – W a – Q 4 Q 2 Process, Energy and System  Incorrect !! W a (1:1 Power to Heat) Above Q 1 Pinch b) Across Pinch Q 4 W b  Correct !! Q = 0 (Saving ST & CW) Q 3 Below W c Q 6 c) Below Pinch Pinch  Awful!! Q 5 ( Power to CW!! ) Q C,min – Q 3 + W c Correct Integration T. Gundersen Integration 7

Correct Integration Process Distillation Heat Steam Process, Energy and System Cascade Column Pump Turbine Q H,min Q Reboiler Q HP,out Q ST,in Above Pinch W ST W HP Q = 0 Below Pinch Q HP,in Q ST,out Q Condenser Q C,min Correct Integration T. Gundersen Integration 8

The Qualitative Approach • Advantages: Process, Energy and System § Very Simple Rules (Connect Sources with Sinks to obtain Benefits) § Powerful in eliminating poor Solutions § The Concept is easy to Understand • Disadvantages: § Provides “yes/no” answers only § Need to know how much Heat we can “correctly” integrate § Need Load and Level (T’s and Q’s) • The Solution: § Use the Grand Composite Curve Correct Integration T. Gundersen Integration 9

Correct Integration of Steam Turbines Process, Energy and System Turbine W VHP T (°C) HP 300 MP 250 LP 200 150 100 H (kW) Firing Correct Integration T. Gundersen Integration 10

Basic Principle for Combined Cycle Plant 10% Ref.: Olav Bolland Process, Energy and System 30% 100% 20% 40% Correct Integration T. Gundersen Integration 11

Combined Cycle Power Plant Power Production only Heat & Power Production Process, Energy and System + + P Q 48 . 5 41 η = = = 89 . 5 % E 100 57 = P 48 . 5 P η = = η = = = 48 . 5 % 57 % E 100 E 100 Ref.: Olav Bolland Correct Integration T. Gundersen Integration 12

Heat Pumps & Refrigeration Cycles Process, Energy and System Heat Pump: COP = γ = Q H / W cycle Refrigeration: COP = β = Q C / W cycle If W cycle → 0 then COP → ∞ but: COP limited by T H and T C Correct Integration T. Gundersen Integration 13

Basic Principle for Heat Pumps Process, Energy and System Correct Integration T. Gundersen Integration 14

Correct Integration of Heat Pumps T’ (°C) Process, Energy and System 190 160 Q 2 130 W Compressor 100 Q 1 70 40 H (kW) “Closed” Heat Pump 0 500 1500 Correct Integration T. Gundersen Integration 15

“Open” Vapor Recompression Heat Pump Process, Energy and System CW Feed Distillate W Bottoms Correct Integration T. Gundersen Integration 16

Correct Integration of Separation Systems • Thermally driven Separation: Process, Energy and System § Distillation Columns § Evaporators (briefly) § Dryers not discussed • Established for Distillation: § T C > T Pinch è Integrate Condenser ( Q C ) § T R > T Pinch > T C è Do not Integrate § T Pinch > T R è Integrate Reboiler ( Q R ) • Heat Recovery Options include: § Integration with Background Process § Integration between Columns Correct Integration T. Gundersen Integration 17

WS-3: Integration of Distillation Column Δ H Stream T s T t mCp Process, Energy and System °C °C kW/°C MW Spec.: H1 220 50 100 17 Δ T min H2 120 120 CON 3 = 20°C C1 20 80 50 3 C2 80 150 200 14 C3 130 130 REB 3 Task: How much Energy can be saved by integrating the Column (H2, C3) with the rest of the Process ? Correct Integration T. Gundersen Integration 18

WS-3: The Composite Curves T (°C) 230 Process, Energy and System 200 170 140 110 80 50 20 H (MW) 0 0 3 6 9 12 15 18 21 24 Correct Integration T. Gundersen Integration 19

WS-3: Without Integration of the Column T (°C) 230 Process, Energy and System 200 170 140 110 80 50 20 H (MW) 0 0 3 6 9 12 15 18 21 24 Correct Integration T. Gundersen Integration 20

WS-3: Restoring the Composite Curves T (°C) 230 Process, Energy and System 200 170 140 110 80 50 20 H (MW) 0 0 3 6 9 12 15 18 21 24 Correct Integration T. Gundersen Integration 21

WS-3: Shifting of the Composite Curves T (°C) 230 Process, Energy and System 200 170 140 110 80 50 20 H (MW) 0 0 3 6 9 12 15 18 21 24 Correct Integration T. Gundersen Integration 22

WS-3: Without Integration T (°C) 230 Process, Energy and System Q H,tot = Q proc . + Q col . 200 = 2 + 3 170 = 5 MW 140 110 80 50 20 H (MW) 0 0 3 6 9 12 15 18 21 24 Correct Integration T. Gundersen Integration 23

Graphical Representations for Distillation Columns Process, Energy and System T (°C) T (°C) 230 A 200 170 140 B 110 C 80 D 50 20 H (MW) H (MW) 0 0 3 6 9 12 15 18 21 24 Part of Composite Curves Box Diagrams indicate is not good (wrong answer) Integration Options Correct Integration T. Gundersen Integration 24

From the Illustrating Example 160° Process, Energy and System Compressor 130° Condenser 210° 270° Distillation Reactor 50° Column 160° 210° Feed Distillation Column Reboiler 60° 220° and Heat Integration ? Product Correct Integration T. Gundersen Integration 25

Data Extraction for the Example Stream ID T s T t mCp Δ H h °C °C kW/°C kW kW/m 2 °C Process, Energy and System Reactor outlet H1 270 160 18 1980 0.5 Product H2 220 60 22 3520 0.5 Feed Stream C1 50 210 20 3200 0.5 Recycle C2 160 210 50 2500 0.5 Reboiler C3 220 220 2000 1.0 Condenser H3 130 130 2000 1.0 HP Steam HP 250 250 (var.) 2.5 MP Steam MP 200 200 (var.) 2.5 LP Steam LP 150 150 (var.) 2.5 Cooling Water CW 15 20 (var.) 1.0 Correct Integration T. Gundersen Integration 26

Graphical Representations T' (°C) for Distillation Columns Process, Energy and System Q H,min Q R 300 Column Data: Q R = Q C = 2000 kW 250 T Reb = 220°C 200 T Con = 130°C 150 100 Grand Composite: Q C 50 Q C,min H (kW) ’ = 230°C T Reb ’ = 120°C T Con 0 500 1000 1500 2000 Correct Integration T. Gundersen Integration 27

WS-3 Continued • Composite Curves (all 5 streams including the Distillation Column) indicated the following: Process, Energy and System T Pinch = 120°C/100°C , Q H,min = Q C,min = 3 MW • With T Reb = 130°C and T Cond = 120°C, the Distillation Column was operating “across the Pinch” and should not be integrated • The “Background Process” (3 streams) requires Q H,BP = Q C,BP = 2 MW and the Column requires Q Reb = Q Cond = 3 MW, a total external Heating and Cooling requirement of 5 MW . • The Background Process Pinch was 100°C/80°C Correct Integration T. Gundersen Integration 28

WS-3 “Andrecovich” Diagram T’ (°C) T’ (°C) More Process, Energy and System 210 210 Reflux 170 170 130 130 90 Q H = 2 + 1 90 Q H = 2 MW = 3 MW 50 50 H (MW) H (MW) 1 1 3 5 7 3 5 7 Correct Integration T. Gundersen Integration 29