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

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

Mar 01, 2024 377 likes •716 views

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)

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SLIDE 1

Correct Integration

  • T. Gundersen

Integration 1

Process, Energy and System Correct Integration

  • Applications:

§ 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

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SLIDE 2

Above Pinch Below Pinch

QH,min QC,min Q = 0

Process Cascade

QReboiler QCondenser

Distillation Column

Correct Integration of Distillation Columns

  • T. Gundersen

Integration 2

Process, Energy and System Correct Integration Above Pinch Below Pinch

QH,min

  • QCondenser

QC,min Q = 0 QReboiler QCondenser Savings from Integration: QCondenser in External Heating and Cooling

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SLIDE 3

Correct Integration of Distillation Columns

  • T. Gundersen

Integration 3

Process, Energy and System Correct Integration Above Pinch Below Pinch

QH,min

  • QC1 + QR2

Q = 0 QR1 QC1 QC3 QR3 QC,min

  • QR3 + QC2

QC2 QR2

Above Pinch  Correct !! (Saving Qcond) Across Pinch  Incorrect !! (No Savings) Below Pinch  Correct !! (Saving Qreb)

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SLIDE 4

Correct Integration of Distillation Columns

  • T. Gundersen

Integration 4

Process, Energy and System Correct Integration

QR1 QC1

Below Pinch

QH,min - QC1 Q = 0 QC,min

Correct Integration but How much Heat can be correctly integrated ?? Heat Cascade provides the answer

Ri ' = Ri −QC1 ≥ 0

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SLIDE 5

Above Pinch Below Pinch

QH,min QC,min Q = 0

Process Cascade Steam Turbine

Correct Integration of Steam Turbines

  • T. Gundersen

Integration 5

Process, Energy and System Correct Integration Above Pinch Below Pinch

QH,min

  • Q2

QC,min Q = 0 Q1 Q2 Q1 – Q2 = W Thermal Energy (Heat) converted to Mechanical Energy (Power)

  • n 1:1 Basis !!

Q1 Q2 W W

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SLIDE 6

Correct Integration of Steam Turbines

  • T. Gundersen

Integration 6

Process, Energy and System Correct Integration Above Pinch Below Pinch

QH,min

  • Q2 + Q3

Q = 0 Q1 Q2 Q6 Q5 QC,min

  • Q5 + Q4

Q4 Q3

Above Pinch  Correct !! (”backpressure”) Across Pinch  Incorrect !! (No Savings) Below Pinch  Correct !! (but practical?)

Wa Wb Wc

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SLIDE 7

Correct Integration of Heat Pumps

  • T. Gundersen

Integration 7

Process, Energy and System Correct Integration

a) Above Pinch  Incorrect !! (1:1 Power to Heat) b) Across Pinch  Correct !! (Saving ST & CW) c) Below Pinch  Awful!! (Power to CW!!)

Above Pinch Below Pinch

QH,min – Wa – Q4 Q = 0 Q2 Q1 Q6 QC,min – Q3 + Wc Q3 Q4 Wa Wb Wc Q5

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SLIDE 8

Above Pinch Below Pinch

QH,min QC,min Q = 0

Process Cascade

QReboiler QCondenser

Distillation Column Heat Pump

QHP,out QHP,in WHP

Steam Turbine

QST,in QST,out WST

Correct Integration

  • T. Gundersen

Integration 8

Process, Energy and System Correct Integration

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SLIDE 9

The Qualitative Approach

  • T. Gundersen

Integration 9

Process, Energy and System Correct Integration

  • Advantages:

§ 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

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SLIDE 10

Correct Integration of Steam Turbines

300 250 200 150 100

T (°C) H (kW)

Firing

VHP HP MP LP

Turbine

W

  • T. Gundersen

Integration 10

Process, Energy and System Correct Integration

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SLIDE 11

Basic Principle for Combined Cycle Plant

  • T. Gundersen

Integration 11

Process, Energy and System Correct Integration

Ref.: Olav Bolland

100% 40% 30% 10% 20%

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SLIDE 12

Combined Cycle Power Plant

  • T. Gundersen

Integration 12

Process, Energy and System Correct Integration

% 5 . 48 100 5 . 48 % 5 . 89 100 41 5 . 48 = = = = + = + = E P E Q P η η % 57 100 57 = = = E P η

Power Production only Heat & Power Production

Ref.: Olav Bolland

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SLIDE 13
  • T. Gundersen

Integration 13

Process, Energy and System Correct Integration

Heat Pumps & Refrigeration Cycles

Heat Pump:

COP = γ = QH / Wcycle

Refrigeration:

COP = β = QC / Wcycle If Wcycle → 0 then COP → ∞ but: COP limited by TH and TC

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SLIDE 14
  • T. Gundersen

Integration 14

Process, Energy and System Correct Integration

Basic Principle for Heat Pumps

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SLIDE 15

190 160 130 100 70 40 T’ (°C)

H (kW)

500 1500

Compressor

W

Q1 Q2

“Closed” Heat Pump

  • T. Gundersen

Integration 15

Process, Energy and System Correct Integration

Correct Integration of Heat Pumps

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SLIDE 16

W Distillate Bottoms Feed CW

  • T. Gundersen

Vapor Recompression

“Open” Heat Pump

Integration 16

Process, Energy and System Correct Integration

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SLIDE 17

Correct Integration of Separation Systems

  • T. Gundersen

Integration 17

Process, Energy and System Correct Integration

  • Thermally driven Separation:

§ Distillation Columns § Evaporators (briefly) § Dryers not discussed

  • Established for Distillation:

§ TC > TPinch è Integrate Condenser (QC) § TR > TPinch > TC è Do not Integrate § TPinch > TR è Integrate Reboiler (QR)

  • Heat Recovery Options include:

§ Integration with Background Process § Integration between Columns

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SLIDE 18

WS-3: Integration of Distillation Column

Stream Ts Tt mCp ΔH °C °C kW/°C MW H1 220 50 100 17 H2 120 120 CON 3 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 ?

Spec.: ΔTmin = 20°C

  • T. Gundersen

Integration 18

Process, Energy and System Correct Integration

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SLIDE 19

WS-3: The Composite Curves

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230

  • T. Gundersen

Integration 19

Process, Energy and System Correct Integration

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SLIDE 20

WS-3: Without Integration of the Column

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230

  • T. Gundersen

Integration 20

Process, Energy and System Correct Integration

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SLIDE 21

WS-3: Restoring the Composite Curves

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230

  • T. Gundersen

Integration 21

Process, Energy and System Correct Integration

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SLIDE 22

WS-3: Shifting of the Composite Curves

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230

  • T. Gundersen

Integration 22

Process, Energy and System Correct Integration

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SLIDE 23

WS-3: Without Integration

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230

  • T. Gundersen

QH,tot = Qproc. + Qcol. = 2 + 3 = 5 MW

Integration 23

Process, Energy and System Correct Integration

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SLIDE 24

Graphical Representations for Distillation Columns

3 6 9 12 15 18 110 170 20 50 80 140 200 H (MW) T (°C) 21 24 230 H (MW) T (°C)

A B C D Part of Composite Curves is not good (wrong answer) Box Diagrams indicate Integration Options

  • T. Gundersen

Integration 24

Process, Energy and System Correct Integration

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SLIDE 25
  • T. Gundersen

From the Illustrating Example

Reactor Feed Product Distillation Column Compressor 50° 210° 160° 210° 130° 220° 160° 270° 60° Reboiler Condenser

Distillation Column and Heat Integration ?

Integration 25

Process, Energy and System Correct Integration

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SLIDE 26
  • T. Gundersen

Integration 26

Process, Energy and System Correct Integration

Data Extraction for the Example

Stream ID Ts Tt mCp ΔH h °C °C kW/°C kW kW/m2 °C 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

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SLIDE 27

Graphical Representations for Distillation Columns

300 250 200 150 100 50

T' (°C) H (kW)

500 1500

QH,min QC,min Column Data: QR = QC = 2000 kW TReb = 220°C TCon = 130°C

Grand Composite: TReb

’ = 230°C

TCon

’ = 120°C

2000 1000

QR QC

  • T. Gundersen

Integration 27

Process, Energy and System Correct Integration

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SLIDE 28

WS-3 Continued

  • T. Gundersen
  • Composite Curves (all 5 streams including the

Distillation Column) indicated the following: TPinch = 120°C/100°C , QH,min = QC,min = 3 MW

  • With TReb = 130°C and TCond = 120°C, the

Distillation Column was operating “across the Pinch” and should not be integrated

  • The “Background Process” (3 streams) requires

QH,BP = QC,BP = 2 MW and the Column requires QReb = QCond = 3 MW, a total external Heating and Cooling requirement of 5 MW.

  • The Background Process Pinch was 100°C/80°C

Integration 28

Process, Energy and System Correct Integration

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SLIDE 29
  • T. Gundersen

WS-3 “Andrecovich” Diagram

50 90 130 170 210

T’ (°C) H (MW)

QH = 2 + 1 = 3 MW

1 3 5 7 50 90 130 170 210

T’ (°C) H (MW)

QH = 2 MW

1 3 5 7

More Reflux

Integration 29

Process, Energy and System Correct Integration

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SLIDE 30

Alternative Evaporator Designs

(CJ Geankoplis: Transport Process & Unit Operations)

a) Horizontal Tube b) Vertical Tube c) Long tube Vertical d) Forced Circulation

  • T. Gundersen

Integration 30

Process, Energy and System Correct Integration

Purpose: Solvent is removed from Solute

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SLIDE 31
  • T. Gundersen

Multi-Effect Evaporation

Integration 31

Process, Energy and System Correct Integration

Here: Forward Feed Arrangement

T1 > T2 > T3 è P1 > P2 > P3 We also have: C3 > C2 > C1

Product ST CW Feed

T1 P1 C1 T2 P2 C2 T3 P3 C3

Condensate

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SLIDE 32
  • T. Gundersen

Evaporators in TQ Diagrams

Integration 32

Process, Energy and System Correct Integration

T H

Steam Off-gas (”vapor”)

T H

Steam Off-gas

Single Effect Multi Effect