SIMULATION AND OPTIMIZATION OF BUTANE AUTOTHERMAL

REFORMER FOR FUEL CELL APPLICATIONS

MOHAMAD SHAHIR BIN ABDULLAH

UNIVERSITI TEKNOLOGI MALAYSIA

iii

Dedicated to my family and friends

iv

ACKNOWLEDGEMENTS

Thank God for giving the opportunity of studying this particular research and

successfully finished it on time. Many obscures happened throughout this study

from the research background to the results of the study. I acknowledge with

appreciation the suggestions, counsel and encouragement from many people directly

or indirectly contributed to the contents of this study. My appreciations go to

supervisor, Engr. Mohd Kamaruddin Abd Hamid for continually giving ideas and

critics. To my colleagues Aifa, Azmil, Cosmas, Farhana, Henry, Badri and Syafiq,

these guys were relentlessly helped me out in making this study completed. I also

would like to thank Assoc. Prof. Dr. Maketab Mohamed and Assoc. Prof. Dr. Mohd

Ghazali Mohd Nawawi for the guides during the process of selecting the research

scope which I interested in. They also have played the role of making the research a

success. Great thanks to my family for supporting me in my life. Thanks to all

people that have been mentioned or carelessly missed to mention that I must

apologise. Thank you.

v

ABSTRACT

Hydrogen (H2) production has gaining popularity among researchers to aim a

better future environment. H2 is very excellent candidate to replace the existing fuel.

Its high flammability and energy produced alongside no side product generated make

it even more popular. The objective of the study is to develop a general steady-state

simulation of H2 production plant for fuel cell application using butane as the

feedstock. The scopes of the study include stoichiometry mathematical calculations,

base case steady-state simulation, base case simulation validation, a design of heat

integration, carbon monoxide (CO) clean-up processes which contains water gas shift

(WGS) and preferential oxidation (PrOx) reactors and plant wide optimization. The

simulation has been run in Aspen HYSYS 2004.1 in steady-state mode in which

optimization was done to generate more H2 as well as CO reduction. The butane fuel

processor was optimized at O/C ratio of 2.18 and S/C ratio of 4.6 to produce 39.2%

of H2 and has achieved 78.1% efficiency. While CO clean-up units was capable to

reduce the CO concentration down to 10 ppm.

vi

ABSTRAK

Penghasilan hidrogen (H2) telah menjadi semakin popular dikalangan

pengkaji-pengkaji bertujuan supaya alam sekitar menjadi lebih baik. H2 adalah calon

yang terbaik untuk menggantikan bahan bakar yang digunakan sekarang.

Kebolebakarannya yang tinggi dan mengeluarkan tenaga yang banyak serta tidak

menghasilkan produk sampingan menjadikan ia semakin popular. Objectif kajian ini

ialah untuk membangunkan simulasi mod malar penghasilan H2 melalui pengubah

terhaba sendiri untuk aplikasi sel bahan bakar menggunakan butana sebagai bahan

muatan. Skop-skop kajian ini termasuklah pengiraan matematik stoikiometri,

simulasi keadaan-malar asas, pengesahan simulasi keadaan-malar asas,

merekabentuk integrasi haba, proses pembersihan karbon monoksida yang

mempunyai pertukaran gas berair (WGS) and pengoksidaan terpilih (PrOx) reaktor

dan pengoptimuman loji keseluruhan. Simulasi telah dijalankan menggunakan

perisian Aspen HYSYS 2004.1 dalam mod malar di mana pengoptimuman telah

dilakukan supaya H2 yang dihasilkan lebih banyak disamping mengurangkan CO.

Pemproses bahan bakar butana ini berada pada keadaan optimum apabila nisbah O/C

bernilai 2.18 dan nisbah S/C bernilai 4.6 yang mengandungi 39.2% H2 yang mana

kecekapannya telah mencapai 78.1%. Manakala unit-unit pembersihan CO telah

dapat mengurangkan kepekatan CO sehingga 10 ppm.

vii

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWEDGEMENTS iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

NOMENCLATURE xiv

LIST OF APPENDICES xvi

1 INTRODUCTION 1

1.1 Research Background 1

1.2 Problem Statement 2

1.3 Objective and Scopes of the Study 2

1.4 Report Organization 3

2 LITERATURE REVIEW 4

2.1 Hydrogen Characteristics 4

2.2 Fuel Cell 5

2.3 Hydrogen Production for 6

Fuel Cell Application

viii

2.3.1 Natural Gas 6

2.3.1.1 Methane 6

2.3.1.2 Ethane 7

2.3.1.3 Propane 7

2.3.1.4 Butane 8

2.3.2 Gasoline 8

2.3.3 Jet Fuel 9

2.3.4 Alcohols 9

2.3.4.1 Methanol 9

2.3.4.2 Ethanol 10

2.3.4.3 Propanol 10

2.3.5 Naphtha 11

2.4 Hydrogen Production from Butane 11

2.4.1 Steam Reforming of Butane 12

2.4.2 Partial Oxidation of Butane 12

2.4.3 Autothermal Reforming of Butane 13

2.5 Carbon Monoxide Clean-up Section 14

2.6 Steady-Simulation of Butane 15

Autothermal Reforming

2.7 Summary 15

3 METHODOLOGY 17

3.1 Research Tools 17

3.1.1 Aspen HYSYS 2004.1 17

3.2 Research Activities 18

3.2.1 Data Collection 18

3.2.2 Steady State Model Development 18

3.2.3 Steady State Model Validation 19

3.2.4 Autothermal Reforming Reactor 19

Optimization

3.2.5 Heat Integration Development 20

3.2.6 Carbon Monoxide Clean-up 20

Section Development

3.2.7 Plant Wide Optimization 20

ix

3.2 Summary 20

4 SIMULATION AND OPTIMIZATION OF 22

BUTANE AUTOTHERMAL REFORMER FOR

FUEL CELL APPLICATTON

4.1 Process Description of Butane 22

Autothermal Reforming Fuel Processor

4.2 Simulation of Butane Autothermal 23

Reforming Fuel Processor

4.2.1 Physical Properties of the 23

Pure Components

4.2.2 Thermodynamic Property 24

4.2.3 Numerical Methods Solutions 26

4.2.4 Steady State Simulation 27

4.3 Summary 27

5 RESULTS AND DISCUSSIONS

5.1 Stoichiometry Mathematical Analysis 29

5.2 Base Case of Autothermal Reforming Reactor 30

5.3 Base Case Simulation Validations 30

5.4 Autothermal reforming Reactor Optimization 31

5.5 Heat Integration 34

5.6 Carbon Monoxide Cleaning Units 34

5.6.1 Water Gas Shift Reactors 35

5.6.2 Additional Preferential Oxidation Unit 35

5.7 Plant Wide Optimization 37

5.7.1 Preferential Oxidation Inlet 38

Air Optimization

5.7.2 Further Optimization 39

5.8 Temperature and Components Profiles 40

5.8.1 Temperature Profiles of 40

Reactor Operating

5.8.2 Components Profiles in the 41

Outlet Stream

x

5.9 Fuel Processor Efficiency 42

5.10 Summary 43

6 CONCLUSIONS AND RECOMMENDATIONS

6.1 Summary 45

6.2 Conclusions 46

6.3 Recommendation for Future Works 46

REFERENCES 48

Appendices A - D 52 - 58

xi

LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Properties of gasoline, natural gas and hydrogen 5

4.1 Physical Properties of the component 24

5.1 Based Case simulation model 31

5.2 The effects of ATR product stream components 33

5.3 Initial compositions of each reactors product 36

xii

LIST OF FIGURES

FIGURE NO. TITLE PAGE

3.1 Algorithm for methodology 21

4.1 Butane ATR fuel processor 23

4.2 Block diagram of the simulation of hydrogen 28

production plant using Aspen HYSYS 2004.1

5.1 Base case of ATR simulation model 30

5.2 Optimization of ATR product stream 32

5.3 Heat integration design 34

5.4 ATR and Water Gas Shift Section 35

5.5 Overall plant diagram with additional 36

preferential oxidation unit

5.6 Water flow optimization 37

5.7 Effects of PrOx air flow to CO concentration 38

xiii

5.8 Steam-to-carbon and air flow effect to 39

CO concentration

5.9 Temperature profiles of the fuel processor 41

5.10 Components profiles 42

xiv

NOMENCLATURE

A = Heat transfer area

ATR = Autothermal reforming

a = Parameter, cubic equation of state

b = Parameter, cubic equation of state

Cp = Heat capacities, constant pressure

Cpo = Standard heat capacities, constant pressure

F = Volumetric flow rate

g = Local acceleration of gravity

H = Molar or specific enthalpy ≡ U + PV

HID = Specific enthalpy of ideal gas

HTS = High temperature shift

ΔH = Enthalpy change (“heat”) of mixing; also, latent heat of

phase transition

ΔHo298 = Standard enthalpy change

i = Species

LTS = Low temperature shift

LHV = Lower heating value

MTS = Medium temperature shift

MW = Molecular weight

O/C = Oxygen-to-carbon ratio

P = Absolute pressure

Po = Reference pressure

Pci = Critical pressure, species i

Pri = Reduced pressure, species i

xv

p = Bias (steady-state) value

PrOx = Preferential oxidation

Q = Heat •

Q = Rate of heat transfer

S = Molar or specific entropy

SID = Entropy of ideal gas

S/C = Steam-to-carbon ratio

T = Absolute temperature, Kelvins

Tn = Normal boiling point at 25oC, 1 atm

Tci = Critical temperature, species i

Tref = Reference temperature

Tri = Reduced Temperature, species i

t = Time

U = Molar or Specific internal energy

V = Molar or specific volume

Z = Compressibility factor ≡ PV/RT

Superscript / Subscript

ID = Ideal gas

D = Derivative

i = Integral

av = Average

Greek letters

α = Function, cubic equation of state

μ = Viscosity

ρ = Density

ω = Acentric factor

η = Efficiency, %

xvi

LIST OF APPENDICES

APPENDIX TITLE PAGE

A A general fuel processor process flow diagram 52

B The effect of air molar flow to the ATR Vap Out 53

temperature

C The effect of water molar flow to the HE3 Out 54

temperature

D The overall fuel processor system condition 55

CHAPTER I

INTRODUCTION

1.1 Research Background

This study is mainly about general simulation of hydrogen (H2) production

for fuel cell application using butane as a raw material. The H2 produced will be

used in fuel-cell-powered vehicle that is known for its clean and recyclable fuel. In

fact H2 is the most abundant element that makes up over 90 percent of the matter of

universe. When it is used as fuel, it will only produce water. It is such a good

alternative to use H2 as a fuel because of its colourless, odourless and extremely

flammable gas and also the smallest and simplest member of the family of chemical

elements compared with other fuel such as hydrocarbons, alcohols, or coals (Kothari

et al., 2004).

Moreover, no side products are involved in the electrochemical conversions

of H2 with zero emission of hazardous species for instances volatile organic

compound (VOCs), nitrogen oxides (NOx) and carbon oxides (CO) (Darwish et al.,

2004). The main goal of this study is to generate H2 production on-board the vehicle

from hydrocarbon feedstock. It is better than having H2 in pressurized vessel or in

cryogenic state for the reason that safety will be the major concern. Therefore, on-

board conversion of butane into H2 through an efficient and compact fuel processor

is the main reason of this study.

2

1.2 Problem Statement

A simulation of butane reforming is scarce in the recent study for that reason

a general simulation an optimization study of hydrogen production plant had been

carried out. The aims of the study are to study preliminary design parameters for

fuel cell processor, and investigate the H2 production efficiency by using butane as a

raw material and to clean carbon monoxide (CO) that produced prior to combustion

and steam reforming reactions.

1.3 Objective and Scopes of the Study

The objective of this study is to develop a general steady-state simulation of

H2 production plant for fuel cell application using butane as the feedstock. In order

to achieve the objective, scopes as shown below have been planned.

i. Stoichiometry mathematical calculation by using overall reaction to

calculate inputs and outputs flow rate for fuel processor.

ii. Base case steady-state simulation was conducted in a selected simulator. In

this scope, the data and reactions occurred in the autothermal reforming

(ATR) reactor was set.

iii. Base case simulation validation was carried out. The purpose of this scope

was to certify the overall reactions of ATR by distinguishing between

calculated outputs composition and steady-state simulation outputs

composition.

iv. Heat integration process was made to heat up the raw material to 100oC

before entering the ATR reactor. The design of heat integration could also

minimize the heating requirement.

3

v. CO clean-up processes which contains water gas shift (WGS) and

preferential oxidation (PrOx) reactors.

vi. Plant wide optimization where high H2 generation as well as low CO

concentration is needed for better hydrogen processor efficiency.

1.4 Thesis Organization

This thesis consists of 6 chapters. In Chapter 1, the introduction of the study

is briefly discussed. While in Chapter 2 literature reviews from various sources are

deeply understood to provide correct information prior to the simulation basis. Next

is chapter 3 where the methodology of carrying the study is explained briefly. In

addition to Chapter 3, Chapter 4 has more information about the study’s

requirements. Chapter 5 has the results and discussion of the simulation that indicate

how the scopes of the study are achieved. To summarize this study, Chapter 6 was

done to conclude the study and some recommendations were made.

48

REFERENCES

Aartun, I., Gjervan, T., Venvik, H., Görke, O., Pfeifer, P., Fathi, M., Holmena, A.

and Schubert, K. (2004). “Catalytic Conversion of Propane to Hydrogen in

Microstructured Reactors.” Chemical Engineering Journal. 101. 93–99.

Ahmet, K., Gamman, J. and Foger, K. (2002). “Demonstration of LPG-fueled Solid

Oxide Fuel Cell Systems.” Solid State Ionics. 152-153. 485-492.

Aspen Tech. Aspen HYSYS 2004.1 Documentation. Avci, A. K., Trimm, D. L. Aksoylu, A. E. and Onsan, Z. I. (2004). “Hydrogen

Production by Steam Reforming of N-butane over Supported Ni and Pt-Ni

Catalysts.” Applied Catalysis A: General. 258. 235-240.

Basile, A., Gallucci, F. and Paturzo, L. (2005). “Hydrogen Production from

Methanol by Oxidative Steam Reforming Carried out in a Membrane

Reactor.” Catalysis Today. 104. 251-259.

Caglayan, B. S., Avcı, A. K., Onsan, Z. I. and Aksoylu, A. E. (2005). “Production of

Hydrogen over Bimetallic Pt–Ni/d-Al2O3 I. Indirect Partial Oxidation of

Propane.” Applied Catalysis A: General. 280. 181–188.

Chin, S. Y., Chin, Y. H. and Amiridis, M. D. (2006). “Hydrogen Production via the

Catalytic Cracking of Ethane over Ni/SiO2 Catalysts.” Applied Catalysis A:

General. 300. 8-13.

Choudhary, T. V., Sivadinarayana, C., Chusuei, C. C., Klinghoffer, A. and

Goodman, D. W. (2001). “Hydrogen Production via Catalytic

Decomposition of Methane.” Journal of Catalysis. 199. 9-18.

Cipitı, F., Recupero, V. Pino, L., Vita, A. and Lagan, M. (2006). “Experimental

Analysis of a 2kWe LPG-based Fuel Processor for Polymer Electrolyte Fuel

Cells.” Journal of Power Sources. 157. 914-920.

Comas, J., Laborde, M. and Amadeo, N. (2004). “Thermodynamic Analysis of

Hydrogen Production from Ethanol using CaO as a CO2 Sorbent.” Journal of

Power Sources. 138. 61-67.

49

Darwish, N. A., Hilal, N., Versteeg, G. and Heesink, B. (2004). “Feasibility of the

Direct Generation of Hydrogen for Fuel-cell-powered Vehicles On-board

Steam Reforming of Naphtha.” Fuel. 83. 409-417.

Dong, W. S., Roh, H. S., Liu, Z. W., Jun, K. W. and Park, S. E. (2001). “Hydrogen

Production from Methane Reforming Reactions over Ni/MgO Catalyst.”

Bull. Korean Chem. Soc. 22, No. 12. 1323-1327.

Ersoz, A., Olgun, H., Ozdogan, S., Gungor, C., Akgun, F. and Tiris, M. (2003).

“Autothermal Reforming as a Hydrocarbon Fuel Processing Option for PEM

Fuel Cell.” Power Sources. 118. 384-392.

Fraser, S.D., Monsberger, M. and Hacker, V. (2006). “A Thermodynamic Analysis

of the Reformer Sponge Iron Cycle.” Journal of Power Sources. 161. 420-

431.

Galvita, V. and Sunmacher K. (2005) “Hydrogen Production from Methane by

Steam Reforming in a Periodically Operated Two-layer Catalytic Reactor.”

Applied Catalysis A: General. 289. 121-127.

Goula, M. A., Kontou, S. K. and Tsiakaras, P. E. (2004). “Hydrogen Production by

Ethanol Steam Reforming over a Commercial Pd/ γ-Al2O3 Catalyst.”

Applied Catalysis B: Environmental. 49. 135-144.

Junge, H. and Beller, M. (2005). “Ruthenium-catalyzed Generation of Hydrogen

from Iso-propanol.” Tetrahedron Letters. 46. 1031-1034.

Karagiannakis, G., Kokkofitis, C., Zisekas, S. and Stoukides, M. (2005). “Catalytic

and Electrocatalytic Production of H2 from Propane Decomposition over Pt

and Pd in a Proton-conducting Membrane-reactor.” Catalysis Today. 104.

219-224.

Kothari, R., Buddhi, D. and Sawhney, R. L. (2004). “Sources and Technology for

Hydrogen Production: a Review.” Int. J. Global Energy. 21, Nos. 1/2. 154-

178.

Lattner, J. R. and Harold, M. P. (2004). “Comparison of Conventional and

Membrane Reactor Fuel Processors for Hydrocarbon-based PEM Fuel Cell

Systems.” International Journal of Hydrogen Energy. 29. 393-417.

Lin, A. T., Chen, Y. H., Yu, C. C., Liu, Y. C. and Lee, C. H. (2006). “Dynamic

Modeling and Control Structure Design of an Experimental Fuel Processor.”

International Journal of Hydrogen Energy. 31. 413-426.

50

Liu, S., Takahashi, K., Fuchigami, K. and Uematsu, K. (2006). “Hydrogen

Production by Oxidative Methanol Reforming on Pd/ZnO: Catalyst

Deactivation.” Applied Catalysis A: General. 299. 58-65.

Mattos, L. V. and Noronha, F.B., (2005). “Hydrogen Production for Fuel Cell

Applications by Ethanol Partial Oxidation on Pt/CeO2 Catalysts: The Effect

of the Reaction Conditions and Reaction Mechanism.” Journal of Catalysis.

233. 453-463.

Minutillo, M. (2005). “On-board Fuel Processor Modelling for Hydrogen-enriched

Gasoline Fuelled Engine.” International Journal of Hydrogen Energy. 30.

1483-1490.

Mizuno, T., Matsumura, Y., Nakajima, T. and Mishima, S. (2003). “Effect of

Support on Catalytic Properties of Rh Catalysts for Steam Reforming of

2-Propanol.” International Journal of Hydrogen Energy. 28. 1393-1399.

Nakagawa, K., Mikka, N. G. and Ando, T. (2005). “Hydrogen Production from

Methane for Fuel Cell Using Oxidized Diamond-supported Catalysts.”

International Journal of Hydrogen Energy. 30. 201-207.

Otsuka, K., Shigeta, Y. and Takenaka, S. (2002). “Production of Hydrogen from

Gasoline Range Alkanes with Reduced CO2 Emission.” International Journal

of Hydrogen Energy. 27. 11-18.

Recupero, V., Pino, L., Vita, A., Cipiti, F., Cordaro, M. and Lagane, M. (2005).

“Development of a LPG Fuel Cell Processor for PEFC Systems: Laboratory

Scale Evaluation of Autothermal Reforming and Preferential Oxidation

Subunits.” International Journal of Hydrogen Energy. 30. 963-971.

Soo, Y. C., Chin, Y. H. and Amiridis, M. D. (2006). “Hydrogen Production via the

Catalytic Cracking of Ethane over Ni/SiO2.” Applied Catalysis A: General.

300. 8-13.

Suzuki, T., Iwanami, H. and Yoshinari, T. (2000). “Steam Reforming of Kerosene

on Ru/Al2O3 Catalyst to Yield Hydrogen.” International Journal of Hydrogen

Energy. 25. 119-126.

Steinberg, M. (2006). “Conversion of Fossil and Biomass Fuel to Electric Power and

transportation Fuel by high Efficiency Integrated Plasma Fuel Cell (IPFC)

Energy Cycle.” International Journal of Hydrogen Energy. 31. 405-411.

51

Wang, Y. N. and Rodrigues, A. E. (2005) “Hydrogen Production from Steam

Methane Reforming Coupled with in situ CO2 Capture: Conceptual

Parametric Study.” Fuel. 84. 1778-1789.

Xu, Y., Kameoka, S., Kishida, K. Demura, M., Tsai, A. and Hirano, T. (2005).

“Catalytic Properties of Alkali-leached Ni3Al for Hydrogen Production from

Methanol.” Intermetallics. 13. 151-155.

Ye, Y., Liisa, R. S., Munder, B. and Sundmacher, K. (2005). “Partial Oxidation of

N-butane in a Solid Electrolyte Membrane Reactor: Periodic and Steady-state

Operations.” Applied Catalysis A: General. 285. 86-95.