Download - Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

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Page 1: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat Integration

Chapter 9 S,S&L

T&S Section 3.5

Terry Ring

University of Utah

Page 2: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Lost Work = Lost Money

• Transfer Heat from T1 to T2

• ΔT approach Temp. for Heat Exchanger• To= Temperature of Environment• Use 1st and 2nd laws of Thermodynamics

• LW=QToΔT/(T1T2)– ΔT=T1-T2

– To= Environment Temperature

• Q= UAΔTlm=UA (ΔT1-ΔT2)/ln(ΔT1/ΔT2)

T1

T2

Q

Page 3: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Simple Heat Exchange Network (HEN)

Page 4: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Costs

• Heat Exchanger Purchase Cost– CP=K(Area)0.6

• Annual Cost– CA=im[ΣCp,i+ ΣCP,A,j]+sFs+(cw)Fcw

• im=return on investment• Fs= Annual Flow of Steam,

– $5.5/ston to $12.1/ston = s

• Fcw=Annual Flow of Cold Water– $0.013/ston = cw

Page 5: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Capital and Operating Cost Optimization

Page 6: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat Integration

• Make list of HX• Instead of using utilities can you use

another stream to heat/cool any streams?• How much of this can you do without

causing operational problems?• Can you use air to cool?

– Air is a low cost coolant.

• Less utilities = smaller cost of operations

Page 7: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

2011

HPC REAC-2000

Q-2002

HPC VSSL-2000

2037

13

23

2024

XFS1

HPC SPLT-2001

30

2026

HPC PUMP-20002031

Q-2008

2012HPC RCYL-2001

2032

6

HPC MIX-2000

2009

3

1

2004

HPC XCHG-2002

HPC MIX-2001

2010

HPC CMPR-2000

2002Q-2001

7

2008HPC XCHG- 2000

HPC XCHG-2001

2038

2039

2040

2041

HPC XCHG-2003

2014

2025Q-2006

2050

2051

HPC XCHG-1008

HPC FAXR-2000

Q-2004

HPC FAXR-2002

Q-2005

HPC XCHG-2004

2042 2043

28

2052 2053HPC XCHG-2007

2048 2049

HPC FAXR-2001

HPC SPLT-2000

2016

2015

HPC MIX-2002

2018

2017

Q-2003HPC XCHG-2005

2044

2045

2019

HPC XCHG-20062020

2021

2046 2047 HPC VSSL-2001

HPC VSSL-2002

2022

HPC VSSL-2003

HPC XCHG-2009

Q-2007

2027

HPC RCYL-2002

2029

2101

HPC CMPR-2010

HPC MIX-20102102

HPC XCHG-2010

HPC XCHG-2011

2103

2104

2107

2108

HPC MIX-2011

2109 2110

HPC XCHG-2012

2114

2112

HPC VSSL-2010

HPC XCHG-2013

113

21052106

HPC SPLT-2010

HPC FAXR-2010

HPC FAXR-2011

HPC FAXR-2012

HPC MIX-2012

HPC VSSL-2011HPC VSSL-2012

HPC VSSL-2013

HPC XCHG-2016

2115

2116

2117

2118

2119

2120

2121

2122

21462147

2123

125

2124

2129

2128

2127

HPC RCYL-2012

HPC SPLT-2011

2130

2126

HPC PUMP-2010

2131

Q-21082137 HPC RCYL-2011

2132

2005

2111

HPC MIX-2003

HPC CMPR-2001

2033

2034

Q-2009

HPC XCHG-2014

HPC XCHG-2015

Q-2104

Q-2103

Q-2105

HPC XCHG-2017

2142 2143

144 145

2148 2149

2138 2139

2140

2141

Q-2101

HPC SPLT-2003

2135

2035

Q-2106

HPC XCHG-2018

2150 2151

Q-107

HPC XCHG-2019

2152 2153

Q-2102

HPC REAC-2010

HPC RCYL-2000

HPC RCYL-2010

2036

2136

XFS2

MIX-100

2

Page 8: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

2011

HPC REAC-2000

Q-2002

HPC VSSL-2000

2037

13

23

2024

XFS1

HPC SPLT-2001

30

2026

HPC PUMP-20002031

Q-2008

2012HPC RCYL-2001

2032

6

HPC MIX-2000

2009

3

1

2004

HPC XCHG-2002

HPC MIX-2001

2010

HPC CMPR-2000

2002Q-2001

7

2008HPC XCHG- 2000

HPC XCHG-2001

2038

2039

2040

2041

HPC XCHG-2003

2014

2025Q-2006

2050

2051

HPC XCHG-1008

HPC FAXR-2000

Q-2004

HPC FAXR-2002

Q-2005

HPC XCHG-2004

2042 2043

28

2052 2053HPC XCHG-2007

2048 2049

HPC FAXR-2001

HPC SPLT-2000

2016

2015

HPC MIX-2002

2018

2017

Q-2003HPC XCHG-2005

2044

2045

2019

HPC XCHG-20062020

2021

2046 2047 HPC VSSL-2001

HPC VSSL-2002

2022

HPC VSSL-2003

HPC XCHG-2009

Q-2007

2027

HPC RCYL-2002

2029

2101

HPC CMPR-2010

HPC MIX-20102102

HPC XCHG-2010

HPC XCHG-2011

2103

2104

2107

2108

HPC MIX-2011

2109 2110

HPC XCHG-2012

2114

2112

HPC VSSL-2010

HPC XCHG-2013

113

21052106

HPC SPLT-2010

HPC FAXR-2010

HPC FAXR-2011

HPC FAXR-2012

HPC MIX-2012

HPC VSSL-2011HPC VSSL-2012

HPC VSSL-2013

HPC XCHG-2016

2115

2116

2117

2118

2119

2120

2121

2122

21462147

2123

125

2124

2129

2128

2127

HPC RCYL-2012

HPC SPLT-2011

2130

2126

HPC PUMP-2010

2131

Q-21082137 HPC RCYL-2011

2132

2005

2111

HPC MIX-2003

HPC CMPR-2001

2033

2034

Q-2009

HPC XCHG-2014

HPC XCHG-2015

Q-2104

Q-2103

Q-2105

HPC XCHG-2017

2142 2143

144 145

2148 2149

2138 2139

2140

2141

Q-2101

HPC SPLT-2003

2135

2035

Q-2106

HPC XCHG-2018

2150 2151

Q-107

HPC XCHG-2019

2152 2153

Q-2102

HPC REAC-2010

HPC RCYL-2000

HPC RCYL-2010

2036

2136

XFS2

MIX-100

2

Page 9: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Terms

• HEN=Heat Exchanger Network

• MER=Maximum Energy Recovery

• Minimum Number of Heat Exchangers

• Threshold Approach Temperature

• Optimum Approach Temperature

Page 10: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Process

Page 11: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Minimize UtilitiesFor 4 Streams

Page 12: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Simple HEN

Page 13: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Pinch Analysis1) Adjust Hot Stream Temperatures to Give ΔTmin

Order T’s, 250, 240, 235, 180, 150, 120

Page 14: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.
Page 15: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Interval Heat Loads

Page 16: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Enthalpy Differences for Temperature Intervals

Page 17: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Pinch Analysis

Minimum Utilities

=ΔHi+50

Page 18: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Pinch Analysis

ΔTapp

MER values

Page 19: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Process

Page 20: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

How to combine hot with cold?

• Big Exhangers 1st

• 1st HX at Pinch (temp touching pinch)– Above Pinch Connect

• Cc≥Ch

– Below Pinch Connect• Ch≥Cc

• 2nd Hx or not touching Pinch temp.– No requirement for Cc or Ch

Page 21: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

4 Heat ExchangerHEN for Min. Utilities

Cc≥Ch Ch≥Cc

MER Values

Page 22: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Pinch Analysis

Minimum Utilities

=ΔHi+50

Page 23: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Minimum Utilities HEN

Page 24: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Simple HEN

Page 25: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Too Many Heat Exchangers

• Sometimes fewer Heat exchangers and increased utilities leads to a lower annual cost

• NHx,min= Ns + NU - NNW

– s=No. streams– U=No. discrete Utilities– NW=No. independent Networks (1 above the pinch, 1 below

the pinch)

• Solution to Too Many Heat Exchangers– Break Heat Exchanger Loops– Stream Splitting

• Attack small Heat Exchangers First

Page 26: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Stream Splitting

• Two streams created from one

• one heat exchanger on each split of stream with couplings

1

1a

1b

1b

1a

1

Page 27: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Break Heat Exchanger Loops

Page 28: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Example

CP=K(Area)0.6

Page 29: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Last Considerations

• How will HEN behave during startup?

• How will HEN behave during shutdown?

• Does HEN lead to unstable plant operation?

Page 30: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

2011

HPC REAC-2000

Q-2002

HPC VSSL-2000

2037

13

23

2024

XFS1

HPC SPLT-2001

30

2026

HPC PUMP-20002031

Q-2008

2012HPC RCYL-2001

2032

6

HPC MIX-2000

2009

3

1

2004

HPC XCHG-2002

HPC MIX-2001

2010

HPC CMPR-2000

2002Q-2001

7

2008HPC XCHG- 2000

HPC XCHG-2001

2038

2039

2040

2041

HPC XCHG-2003

2014

2025Q-2006

2050

2051

HPC XCHG-1008

HPC FAXR-2000

Q-2004

HPC FAXR-2002

Q-2005

HPC XCHG-2004

2042 2043

28

2052 2053HPC XCHG-2007

2048 2049

HPC FAXR-2001

HPC SPLT-2000

2016

2015

HPC MIX-2002

2018

2017

Q-2003HPC XCHG-2005

2044

2045

2019

HPC XCHG-20062020

2021

2046 2047 HPC VSSL-2001

HPC VSSL-2002

2022

HPC VSSL-2003

HPC XCHG-2009

Q-2007

2027

HPC RCYL-2002

2029

2101

HPC CMPR-2010

HPC MIX-20102102

HPC XCHG-2010

HPC XCHG-2011

2103

2104

2107

2108

HPC MIX-2011

2109 2110

HPC XCHG-2012

2114

2112

HPC VSSL-2010

HPC XCHG-2013

113

21052106

HPC SPLT-2010

HPC FAXR-2010

HPC FAXR-2011

HPC FAXR-2012

HPC MIX-2012

HPC VSSL-2011HPC VSSL-2012

HPC VSSL-2013

HPC XCHG-2016

2115

2116

2117

2118

2119

2120

2121

2122

21462147

2123

125

2124

2129

2128

2127

HPC RCYL-2012

HPC SPLT-2011

2130

2126

HPC PUMP-2010

2131

Q-21082137 HPC RCYL-2011

2132

2005

2111

HPC MIX-2003

HPC CMPR-2001

2033

2034

Q-2009

HPC XCHG-2014

HPC XCHG-2015

Q-2104

Q-2103

Q-2105

HPC XCHG-2017

2142 2143

144 145

2148 2149

2138 2139

2140

2141

Q-2101

HPC SPLT-2003

2135

2035

Q-2106

HPC XCHG-2018

2150 2151

Q-107

HPC XCHG-2019

2152 2153

Q-2102

HPC REAC-2010

HPC RCYL-2000

HPC RCYL-2010

2036

2136

XFS2

MIX-100

2

Page 31: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Optimization of HEN

• How does approach ΔT (ΔTmin) effect the total cost of HEN?

• Q= UA ΔT

• LW=QToΔT/(T1T2)

– More Utility cost

Page 32: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

ΔTmin

• S T(C) T(C) CQ(kW)

• H1 300 200 1.5 150

• H2 300 250 2 100

• C1 30 200 1.2 204

LW=QToΔT/(T1T2)

ΔTapp=10C ΔTapp=105C

Page 33: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Costs

• Heat Exchanger Purchase Cost– CP=K(Area)0.6

• Annual Cost– CA=im[ΣCp,i+ ΣCP,A,j]+sFs+(cw)Fcw

• im=return on investment• Fs= Annual Flow of Steam,

– $5.5/ston to $12.1/ston

• Fcw=Annual Flow of Cold Water– $0.013/ston

Page 34: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Change ΔTmin

CP=K(Area)0.6

Area=Q/(UF ΔTmin)

More Lost Work

LW=QToΔT/(T1T2)

Page 35: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Capital and Operating Cost Optimization

ΔTthres

Page 36: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Distillation Columns

Page 37: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heuristic “Position a Distillation Column Between Composite Heating and Cooling Curves”

Page 38: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat Integration for Indirect Distillation Sequence

Page 39: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Multi-effect DistillationAdjust Pressure in C2 for ΔTmin

Page 40: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

• Heat Pumps in Distillation

Page 41: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat PumpsHow do they work?

Convert low temperature heat to high temperature heat.Must add work as heat can not go up hill.

Same as Air Conditioner

Carnot Efficiencyηmax= 1-Tc/Th

Endoreversibleη =1-√(Tc/Th)

Page 42: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat Pumps/Heat Engines Heurisitcs

• When positioning heat engines, to reduce the cold utilities, place them entirely above or below the pinch

• When positioning heat pumps, to reduce the total utilities, place them across the pinch.

Page 43: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat PumpsWhere can they be used?

•Heuristic

•When positioning heat pumps, to reduce the total utilities, place them across the pinch.

Page 44: Heat Integration Chapter 9 S,S&L T&S Section 3.5 Terry Ring University of Utah.

Heat EnginesWhere can they be used?

•Heuristic

•When positioning heat engines, to reduce the cold utilities, place them entirely above or below the pinch

Tp