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PERPUSTAKAAN UTHM
SCANNED AVAILABLE o n l i n e
* 3 0 0 0 0 0 0 1 8 8 3 5 2 5 *
KOLEJ UNIVERSITI TEKNOLOGI TUN HUSSEIN ONN
BORANG PENGESAHAN STATUS TESIS0
JUDUL: DESIGN OF HEAT EXCHANGER NETWORK USING PINCH METHOD
SESI PENGAJIAN: 2006/2007
Saya WAN NURD IY AN A BINTI WAN MANSOR
mengaku membenarkan tesis ( syarat-syarat kegunaan seperti berikut:
: ini disimpan di Perpustakaan dengan
1. Tesis adalah hakmilik Kolej Universiti Teknologi Tun Hussein Onn. 2. Perpustakaan dibenarkan membuat salinan untuk tujuan pengajian sahaja. 3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi
pengajian tinggi. 4. **Sila tandakan (J):
SULIT
T E R H A D
(Mengandungi maklumat yang berdai jah keselamatan atau kepentingan Malaysia yang termaktub di dalam A K T A R A H S I A R A S M I 1972)
(Mengandungi maklumat T E R H A D yang telah ditentukan oleh organisasi/badan di mana penyelidikan dijalankan)
TIDAK T E R H A D
(TAND A T ^ N G A N PENULIS) ( T A N D A T A N G A N J E N Y E L I A )
Alamat Tetap: 27, Jalan Taman Gombak 3, Taman Gombak, 68100, Gombak. Selanpor.
Tarikh: November 2006
PROF. DR. V D A Y R. R A G H A V A N Nama Penyelia
Tarikh: 2 . I f t k November 2006
Potong yang tidak berkenaan. Jika tesis ini SULIT atau TERHAD, sila lampirkan surat dari pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD. Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Saijana secara penyelidikan, atau disertasi bagi pengajian secara kei ja kursus dan penyelidikan, atau Laporan Projek Saijana Muda (PSM).
"I hereby declare that I have read this report and in my opinion this report in terms of
content and quality requirement fulfills the purpose for the conferring of the Master 's
Degree in Mechanical Engineering".
Signature : ' l i ® ^
Name of Supervisor : PROF. DR. VIJAY R. RAGHAVAN
Date NOVEMBER 2006
•\jiiWt
PKOF. DR. VIJAY R. RAGHAVAN Department vt l:! i-h & Automotive Engineering Faculty of Mechanical & Manufacturing Engineering Kolej Universiti Teknologi Tun Hussein Onn
DESIGN OF HEAT EXCHANGER NETWORK
USING PINCH METHOD
WAN NURDIYANA BINTI WAN MANSOR
A dissertation submitted as partial fulfillment of the requirement for the award of
the Master's Degree in Mechanical Engineering
Department of Mechanical Engineering
Faculty of Mechanical and Manufacturing Engineering
Kolej Universiti Teknologi Tun Hussein Onn
NOVEMBER 2006
ii
"I declare that this thesis entitled 'Design of Heat Exchanger Network Using Pinch
Method' is the result of my own work except as cited in references".
Signature
Name of Author
Date
Y s t f p S .
WATsLNURDIYANA BINTI WAN MANSOR
NOVEMBER 2006
I l l
S'OA, rivy, jxurui/ij,,
^VQ. C^HAJQA tt\& lUlXXMl2ti£LQ4lCl£ f
xiv
ACKNOWLEDGEMENT
W i t h a deep sense o f gratitude, I wish to express m y sincere thanks to m y
supervisor, Professor Dr . V i j a y R. Raghavan for his immense help in p lanning and
executing the works in t ime. H e is not only a great professor w i th deep vision but
also and most importantly a k ind person. H i s trust and determination inspired me in
the most important moments o f m a k i n g right decisions and I am glad to work w i th
him. T h e confidence and dynamism with which P r o f V i j a y guided the work requires
no elaboration.
I also want to thank m y parents, who taught m e the value o f hard work by
their o w n example. I wou ld l ike to share this moment o f happiness wi th m y parents,
brothers and sisters. T h e y rendered me enormous support during the whole tenure o f
my studies.
F ina l ly , I w o u l d l ike to thank all whose direct and indirect helped me
complet ing m y thesis in t ime.
xiv
ABSTRACT
Chemica l or o i l ref ineiy processes ut i l ize huge amounts o f energy in their routine
operations. There fore , it is v i ta l for such industries to find ways o f m a x i m i z i n g the use
o f energy and make the system more eff ic ient through reduction in energy, water and
raw mater ial consumption. W a s t e energy can be transferred to another process and that
w i l l increase the prof i tabi l i ty o f the industries. W h e n the use o f a heat exchanger
network (HEN) is considered for these tasks, the f r a m e w o r k developed in this study can
be implemented to m a k e a cost-benefit analysis.
Th is thesis represents a f r a m e w o r k for generat ing the H E N over a specif ied range
o f variat ions in the f l o w rates and temperature o f the streams. So that the heat exchanger
area, n u m b e r o f heat exchange units and load on the heat exchangers can be estimated.
T h e proposed method to analyze and design the H E N is cal led pinch method, wh ich is
one o f the most practical tools and used to improve the ef f ic iency o f energy usage, fuel
and water consumption in industrial processes. Th is method investigates the energy
f lows wi th in a process and identif ies the most economical ways o f m a x i m i z i n g heat
recovery. Th is method consists o f five major steps to f o l l o w , w h i c h w i l l finally lead to
H E N design. T h e steps are: ( 1 ) choose a m i n i m u m temperature approach temperature
( D T m i n ) , ( 2 ) construct a temperature interval d iagram, ( 3 ) construct a cascade d iagram
and determine the m i n i m u m ut i l i ty requirements and the p inch temperature, ( 4 ) calculate
the m i n i m u m number o f heat exchangers above and b e l o w the pinch and (5 ) construct
the heat exchanger network .
T h e emphasis o f this work has been on the designing o f the H E N . H o w e v e r , to
demonstrate the practical impl icat ions o f p inch analysis, D T m i n and the heat exchanger
costs, it is necessary to estimate the heat transfer area o f the H E N , wh ich w i l l help in
arr iv ing at the total cost inc luding capital and running costs o f the designed H E N . T h e
effect o f changing the D T m i n gave a good indicat ion on the overal l costs.
xiv
ABSTRAK
Industri pemprosesan k i m i a atau penapisan minyak banyak menggunakan tenaga
dalam rutin harian mereka. M a k a industri-industri sebegini perlu mencari a l temat i f
untuk memaks imumkan penggunaan tenaga dan memast ikan sistem yang digunakan
adalah efisyen melalui pengurangan da lam penggunaan tenaga, air dan juga bahan
mentah. H a b a buangan daripada proses yang di jalankan boleh dikitar dan diguna semula
untuk digunakan di da lam proses yang lain. Jadi, b i ia alat penukar haba digunakan di
dalam proses yang disebutkan di atas, m a k a ke i ja di da lam tesis ini boleh digunakan
untuk mengurangkan penggunaan kos untuk industri tersebut.
Tesis ini mempersembahkan ja lan ke i j a untuk merekabentuk 'Rangkaian
Penukar Haba ' . Hasi lnya , kawasan yang diperlukan untuk membina alat-alat penukar
haba ini boleh dikira, begitu j u g a bi langan unit yang diperlukan dan bebanan yang
dikenakan kepada alat penukar haba boleh dianggarkan. Rangkaian yang diusulkan ini
menggunakan kaedah yang dikenal i sebagai Kaedah Pinch. ICaedah ini merupakan
kaedah yang pa l ing praktikal dan digunakan untuk meningkatkan penggunaan tenaga, air
dan bahan mentah secara efisyen. Kaedah ini mengenalpasti tenaga yang boleh dial irkan
dari buangan kepada proses yang berguna dan seterusnya dapat memaks imumkan
penggunaan tenaga. Kaedah ini mengandungi l i m a langkah yang per lu di ikuti: (1 ) p i l ih
suhu rendah yang dibenarkan, ( 2 ) b ina diagram jarak-suhu, ( 3 ) b ina diagram Cascade
dan tentukan keperluan tenaga m i n i m u m , (4 ) k ira bi langan alat penukar haba yang
diperlukan dan (5 ) b ina rangkaian alat penukar haba.
O b j e k t i f u tama tesis ini adalah merekabentuk rangkaian alat penukar haba,
namun sebagai pelengkap kepada keperluan ekonomi , tesis ini turut mendemonstrasi
kesan daripada penggunaan kaedah pinch ini dengan suhu m i n i m u m yang dipi l ih dan
j u g a kos untuk membina rangkaian alat penukar haba. Kos-kos ini termasuk kos untuk
m e m b i n a kawasan, kos pembuatan alat penukar haba dan lain-lain. Kos ini disebut
Vlll
sebagai kos u t a m a y a n g mei ibatkan kos permulaan untuk memulakan operasi. M a n a k a l a
kos tahunan atau kos yang perlu ditanggung sepanjang industri ini menjalankan operasi
mereka termasuk kos untuk membel i tenaga, minyak , air dan lain-lain. Dengan menukar
ni la i suhu m i n i m u m yang dipi l ih di da lam langkah (1), kos-kos yang disebutkan akan
berubah dan di sini akan w u j u d t i t ik op t imum yang boleh diaplikasi oleh pihak industri.
V l l l
T A B L E O F C O N T E N T S
C H A P T E R C O N T E N T S P A G E
D E C L A R A T I O N i i
D E D I C A T I O N in
A C K N O W L E D G E M E N T iv
A B S T R A C T v
A B S T R A K vi
T A B L E O F C O N T E N T S v i i i
L I S T O F T A B L E S xi
L I S T O F F I G U R E S x i i
N O M E N C L A T U R E x i v
L I S T O F A P P E N D I X E S xv i i
1 I N T R O D U C T I O N
1.1 Background o f the Prob lem 3
1.2 Object ives 4
1.3 Scope o f W o r k 5
1.4 T h e Importance o f the Research 5
I I L I T E R A T U R E R E V I E W
2.1 Introduction to Hea t Exchanger N e t w o r k Analysis 8
2.2 Pinch Design M e t h o d 9
2 .21 Pinch Appl icat ion 15
2.3 Mathemat ica l Programming Approach 17
2 .3 .1 Sequential Approach 17
2 .3 .2 Simultaneous Approach 18
RESEARCH METHODLOGY
3.1 Introduction 22
3.1.1 O v e r v i e w o f Pinch Design M e t h o d 22
3 .1 .2 W h a t is Pinch Technology? 23
3.1.3 Object ives o f P inch Analysis 24
3 .2 Steps in Pinch Analysis 26
3 .2 .1 Thermal Da ta for Process and U t i l i t y Streams 26
3 .2 .2 Step 1: Choose a M i n i m u m Approach Temperature
( D T m i n ) 2 7
3.2.3 Step 2: Construct a Temperature Interval D i a g r a m 28
3.2.4. Step 3: Construct a Cascade D i a g r a m 29
3.2.5 Step 4: Calculate the M i n i m u m N u m b e r o f H e a t
Exchanger 30
3 .2 .6 Step 5: Design the Heat Exchanger N e t w o r k 30
3.2.6.1 Design above the Pinch 31
3 .2 .6 .2 Des ign b e l o w the Pinch 32
3.3 Composi te Temperature Enthalpy D i a g r a m 32
3.4 H e a t Transfer Area Calculat ion 33
3.5 Basic Design Procedure o f a H e a t Exchanger 34
3.6 T h e Design o f Shel l -and-Tube H e a t Exchangers 35
3.6.1 Hea t Transfer and Pressure Drop Calculations 36
3 .6 .1 .1 Shel l -Side H e a t Transfer Coef f ic ient 3 7
3 .6 .1 .2 Shel l -Side Pressure Drop 39
3.6 .2 Rat ing Procedure 41
3.6.3 Approx imate Design M e t h o d 43
3.6.3.1 Exchanger D imens ion 44
I V A N A L Y S I S A N D D I S C U S S I O N
4.1 Introduction and the D a t a Prob lem 46
4.2 M i n i m u m temperature approach o f 10°C 4 7
4.3 Des ign A b o v e the Pinch 50
4.4 Des ign B e l o w the Pinch 52
4.5 Analysis for the M i n i m u m Temperature
Approach o f 15°C 56
4.6 Analysis for the M i n i m u m Temperature
Approach o f 20 °C 60
4 .7 Shel l -and-Tube H e a t Exchanger 65
4.8 H e a t Exchanger Specif ication 68
4.9 Discussion 69
V C O N C L U S I O N A N D R E C O M M E N D A T I O N
5.1 Conclusion 71
5.2 Recommendat ion 72
R E F E R E N C E S 73
A P P E N D I X E S 79
xiv
LIST OF TABLES
TABLE NO. TITLE PAGE
1.1 PS Gantt Chart 6
3.1 Typica l Va lues o f D T m i n in Industrial Processes 28
4.1 Stream and T h e r m a l D a t a for Pinch Analysis 4 7
4 .2 Processes-to-Process Exchanger A r e a 55
4.3 H o t U t i l i t y Exchanger Area 55
4.4 C o l d Ut i l i t y Exchanger Area 55
4.5 Processes-to-Process Exchanger A r e a 58
4.6 H o t Ut i l i ty Exchanger A r e a 59
4 .7 Cold Ut i l i ty Exchanger A r e a 59
4.8 Processes-to-Process Exchanger A r e a 62
4 .9 H o t Ut i l i ty Exchanger Area 63
4 .10 Co ld Ut i l i ty Exchanger Area 63
4.11 S u m m a i y o f the Calculated Stream D a t a 63
4 .12 Hea t Exchanger Specif ication Used in the Design 69
xn
LIST OF FIGURES
FIGURE NO. TITLE PAGE
1.1 On ion D i a g r a m o f H ierarchy in Process Design 2
2.1 Shel ls-and-Tube Hea t Exchanger 8
3.1 Strategy for the H E N synthesis using pinch approach 25
3.2 Basic Log ic Structure for Process Hea t Exchanger Des ign 34
4.1 Temperature Intervals D iagram wi th D T m i n 10°C 64
4.2 Cascade D i a g r a m w i t h D T m i n 10°C 49
4.3 H e a t L o a d A b o v e the Pinch Point 50
4.4 Hea t L o a d B e l o w the Pinch 51
4.5 Des ign o f H E N A b o v e the Pinch Point 52
4.6 Des ign o f H E N B e l o w the Pinch 53
4 .7 Temperature Enthalpy D i a g r a m
for the Case o f D T m i n is 10°C 54
4.8 Temperature Interval D i a g r a m
for the Case o f D T m i n = l 5°C 56
4.9 Cascade D i a g r a m for the Case o f D T m i n = 1 5 ° C 57
4 .10 Designs A b o v e the Pinch 5 7
4 .11 Designs B e l o w the Pinch 58
4 .12 Temperature Interval D i a g r a m
for the Case o f D T m i n = 2 0 ° C 60
4.13 Cascade D i a g r a m 61
4 .14 Designs A b o v e the Pinch 61
4.15 Designs B e l o w the Pinch 62
4 .16 T h e Ef fect o f U s i n g D i f fe rent D T m i n 64
4.17 Shel l -and-Tube Hea t Exchanger w i th
one-shell and two-passes 65
4 .18 T h e Types o f Front E n d Used in the Design 66
4 .19 T h e Types o f Shells Used in the Des ign 67
4 .20 T h e Types o f Rear E n d Used in the Design 68
xiv
NOMENCLATURE
A H e a t Exchangers A r e a
As Shel l -Side or T u b e Outside Surface A r e a
Cp Specific H e a t Capacity
d0 T u b e D iamete r
DP s-actual Actual Pressure D r o p in the Shel l -Side
DPs-id Ideal Pressure D r o p in the Shel l -Side
A Shell D i a m e t e r
DTin, Temperature D i f fe rence at Each Interval
D T m i n M i n i m u m A l l o w a b l e Temperature D i f fe rence
F L M T D Correct ion Factor
F, Correction Factor for the T u b e Outside D iamete r and T u b e L a y o u t
F2 Correct ion Factor for the N u m b e r o f T u b e Passes
F3 Correct ion Factor Var ious R e a r - E n d H e a d Designs
h Heat Transfer Coef f ic ient
H D D H u m i d i f i c a t i o n - D e h u m i d i f i c a t i o n Desal inat ion
H E N Hea t Exchanger N e t w o r k
Ihd Ideal H e a t Transfer Coef f ic ient
hs Shel l -Side H e a t Transfer Coef f ic ient
Jb Correct ion Factor for B u n d l e
Jo Correct ion Factor for B a f f l e Conf igurat ion
Ji Correct ion Factor for B a f f l e Leakage Effects
Jr Correct ion Factor for A n y Adverse Temperature Gradient
Js Correction Factor for L a r g e r B a f f l e Spacing
k Therma l Conduct iv i ty
L T u b e Length
Leff Effect ive T u b e Length
xiv
L M T D Logar i thmic M e a n Temperature Di f ference
L P L inear Programming
m F l o w Rate
m C p Hea t Capacity F l o w Rate
MTT.P M i x e d Integer L inear Programming
M 3 N L P M i x e d Integer Nonl inear Programming
M O - M I L P M u l t i - O b j e c t i v e M i x e d - I n t e g e r L inear Programming
NH N u m b e r o f Baf f les
N L P Nonl inear Programming
NK CC N u m b e r o f T u b e R o w s Crossed D u r i n g F l o w Through One Crossf low in
the Exchanger
TV,. CTl. N u m b e r o f T u b e R o w s Crossed in Each Baf f le W i n d o w
N , N u m b e r O f Tubes
N u Nusselts N o .
P D M Pinch Design M e t h o d
Ps Temperature Effectiveness
O Hea t Supp ly /Demand
Qmailable Heat Ava i lab le
Q C Co ld Enthalpy
Q H H o t Enthalpy
O m t Hea t for Each Interval
RS Heat Capacity Rat io
S T H X Shel l -and-Tube Hea t Exchanger
T E M A Tubular Exchanger Manufacturers ' Association
T - H Temperature-Enthalpy
T - I Temperature Interval
T i n Supply Temperature
Tout Target Temperature
U Overal l Hea t Transfer Coef f ic ient
US Overal l Shel l -Side Heat Transfer Coeff ic ient
W W o r k D o n e
x v i
AH Enthalpy Change
AP Pressure Drop
APb,id Ideal Pressure Drop in the Central Section
APcr Pressure D r o p in the Central (Crossf low) Section
AP,-0 Pressure Drop in the Shel l -Side Inlet A n d Outlet Sections
APW Pressure D r o p in the W i n d o w Area
Q) Correction Factor for Bypass F l o w
Q Correct ion Factor for Tube - to -Ba f f l e and Baf f le - to-Shel l Leakage
Streams
6 ' Correction Factor for In le t and Outlet Sections
t| Viscosi ty
p Densi ty
xvii
LIST OF APPENDIXES
APPENDIX TITLE PAGE
A Tube outside (shell side) surface area A s as a function o f
shell inside diameter and effect ive tube length 80
B Va lues o f F i for Var ious T u b e Diameters and Layouts 81
C Va lues o f F2 for Var ious N u m b e r s o f Tube-Passes 82
D Va lues o f F 3 for Var ious T u b e Bundle Constructions 83
E Typ ica l Ref inery Process 84
F Or ig ina l Paper o f Barbara et al. ( 2 0 0 4 ) 85
1
C H A P T E R I
I N T R O D U C T I O N
T h e transfer o f thermal energy is one o f the most important and frequently
used processes in engineer ing. T h e transfer o f heat is usual ly accompl ished b y a heat
exchanger. A s a heat transfer device, it is the funct ion o f a heat exchanger to transfer
heat as e f f ic ient ly as possible. T h i s makes it the u l t imate device o f choice, for
instance, w h e n it comes to saving energy b y recover ing wasted heat and m a k i n g it
useful again. W h e n there is a waste o f energy or a hot stream that is not recovered, a
pre-heater or recuperator can convert that hot stream into a useful source o f heat i n
other applications.
W h e n designing heat exchangers and other unit operations, l imits exist that
constrain the design. These l imi tat ions are imposed by the first and second laws o f
thermodynamics . I n heat exchangers, a close approach b e t w e e n hot and cold streams
requires a large heat transfer area. W h e n e v e r the dr iv ing force for heat exchange is
smal l , the equipment needed for transfer becomes large and it is said that the design
has a "p inch" . W h e n considering systems o f m a n y heat exchangers, it is ca l led a heat
exchanger n e t w o r k ( H E N ) . T h e r e w i l l exist somewhere in the system a po int where
the dr iv ing force for energy exchange is m i n i m u m . Th is represents a p inch o r p inch
point . T h e successful design o f these ne tworks involves discover ing w h e r e the p i n c h
exists and using this in fo rmat ion at the p inch point to design the w h o l e ne twork . Th is
design process is cal led p i n c h technology.
2
T h e H E N synthesis has been one o f the most w e l l studied in process synthesis
dur ing the last three decades and has been w i d e l y appl ied, especial ly in the
pet ro leum re f in ing and petrochemical industry. T o i l lustrate the role o f H E N in the
overal l process design, consider the "on ion d iagram" ( L i n h o f f et. al., 1982 ) as s h o w n
be low. T h e design o f a process starts w i t h the reactors in the "core" o f the onion.
O n c e feeds, products, recycle concentrations and f lowrates are k n o w n , the separators
( the second layer o f the onion) can be designed. T h e basic process heat and mater ia l
balance is n o w in place, and the H E N (the third layer) can be designed. T h e
remain ing heat ing and cool ing duties are handled by the ut i l i ty system ( the four th
layer) . T h e process ut i l i ty system m a y be a part o f a centralised si tewide u t i l i ty
system.
R < i r i t : l a 6 9 r i p
o 2 (5 Cl
3
be set prior to the design of the heat exchanger network. The pinch design method
ensures that these targets are achieved during the network design.
Process integration using pinch technology offers a chronicle approach to
generate targets for minimum energy consumption before heat recovery network
design. Heat recovery and utility system constraints are then considered in the design
of the core process. Interactions between the heat recovery and utility system are also
considered. The pinch design can reveal opportunities to modify the core process to
improve heat integration. The pinch approach is unique because it treats all processes
with multiple streams as a single, integrated system. This method helps to optimize
the heat transfer equipment during the design of the equipment.
1.1 Background of the Problem
As the heat exchanger consumes energy vastly, it is vital to find a method to
improve the use of energy and reduce capital and utilities cost. Finding ways to
reduce and conserving energy are always a smart way to cut cost. Reduced energy
usage is a big selling point for end users. If the functionality of a product is similar to
the competition, benefits like energy usage win customers. The benefit of reduced
usage cost over time allows manufacturers to charge a higher premium while saving
the customer money in the long run.
Excessive energy consumption by using hot and cold utilities influences the
global cost of industrial processes. The supply and removal of heat in a modern oil
refinery process plant represents an important problem in the process design of the
plant. The cost of facilities to accomplish the desired heat exchange between the hot
and cold media may cost up to one third of the total cost of the plant. To meet the
goal of maximum energy recovery or minimum energy requirement (MER) an
appropriate HEN is required. The design of such a network is not an easy task