Design and Development of Gasification Processes in Fluidised Bed Chemical Reactor Engineering Thesis Submitted to Cardiff University in Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Chemical Engineering-Reactor Design By Mohammed Hussein Ahmed Al-hwayzee B.Sc. Chemical Eng. & M.Sc. Chemical Eng. School of Engineering - Cardiff University Cardiff, Wales, United Kingdom September 2016 DECLARATION This work has not previously been accepted in substance for any degree and is not concurrently submitted in candidature for any degree. Signed …………………….…... (Mohammed H. A. Al-hwayzee) Date 30/09/2016 STATEMENT 1 This thesis is being submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy (PhD). Signed …………………….…. (Mohammed H. A. Al-hwayzee) Date 30/09/2016 STATEMENT 2 This thesis is the result of my own independent work/investigation, except where otherwise stated. Other sources are acknowledged by explicit references. Signed …………………….… (Mohammed H. A. Al-hwayzee) Date 30/09/2016 STATEMENT 3 I hereby give consent for my thesis, if accepted, to be available for photocopying and inter-library loan, and for the title and summary to be made available to outside organisations. Signed …………………….…. (Mohammed H. A. Al-hwayzee) Date 30/09/2016 III ABSTRACT This thesis focuses on studying and investigation the effects of the hydrodynamic and operating parameters in the air-biomass gasification in a bubbling fluidised bed gasifier under low temperature (<800oC) conditions and evaluating the potential of the gasification of two solid biomass waste materials, Iraqi date palm wastes and sawdust pinewood. These parameters are air flowrate, particle size of the sand bed material, biomass particle size, static bed height, air equivalence ratio, bed temperature, number of holes in distributor plates and biomass fuel type. A design study was conducted to provide preliminary data for designing and constructing a large lab-scale fluidised bed column, diameter D=8.3cm, for cold and hot fluidisation experiments. Cold fluidisation experiments were conducted to provide the fluidisation behaviour data for the sand, biomass and their mixture. The design and cold fluidisation results have shown a compatible finding in the following: 1) the design parameter U has shown that, it increases as sand particle size mf increases. 2) It was not affected by static bed height. In addition, cold fluidisation results show that: sand has a high fluidisation quality compared to pure biomass and sand- biomass mixture and there is no effect of the bed static height on the U . mf In general, the studied parameters on the air-biomass gasification performance have shown that: 1) air flowrate has a considerable effect, 2) as sand and biomass particle size increases a weakened gasification was achieved. 3) The static height effect has been observed due to the location of the biomass feeding position thereby affecting reactant residence time. 4) For equivalence ratio range (0.2-0.4) the lowest value provided optimum gas composition and LHV values, whereas the highest value ER= 0.43 provided highest (CCE), CGE) and (GY). 5) No significant effect was seen for bed temperature between 360 to 465oC. 6) A considerable effect has been shown for the distributor plate configuration. Finally, the results has shown that SPWB has potential compared to IDPWB for energy generation. However, additional simulation, optimization and experimental studies on the bubbling fluidised biomass gasification for a broad range of operating and hydrodynamic parameters are hereby suggested. IV DEDICATION To my Imam Al Hujjah Ibnu Alhassen (ajtf) I am your soldier To my parents …… To my wife ….. my love To my lovely daughters….. Safa, Amenah, Nusk and Gherked To my brothers and Sisters V ACKNOWLEDGEMENTS Foremost, I would like to praise and thank my GOD (ALLAH) for helping me to complete this thesis. I would like to extend my thanks to the Iraqi Government-Ministry of Higher Education and Scientific Research, in particular Kerbala University for granting the opportunity to study and complete the PhD. Thanks for the staff of the Iraqi cultural attaché in London for their help during my stay in the UK. The words are not sufficient to express my gratefulness and deepest thanks to my supervisor, Dr. Richard Marsh for his continuous supervision, positive discussions, important ideas through this research work and his various support along my study. Again I repeat my grate thank for him. I would like also to thank the staff of School of Engineering and the staff of the Mechanical Engineering Work Shop. Special thanks for Mr Malcolm Seaborne and other technical staff for their technical supports during experimentation. My thanks for Dr. Julian Steer for his help and support. I must also thank Mr Hussein, the director of the project of the Organic Fertilizer Preparation and Mushroom Cultivation - Karbala City-Iraq and other staff for their help for providing my research an Iraqi date palm wastes biomass material IDPWB. I wish also to thank all the staff of the Research Office, Finance Office and the IT staff in School of Engineering for their help during my study period. I would like to present my thanks for the staff of the Cardiff University Student Support for their helps and advice. I am greatly indebted to my devoted wife. My gratefulness for her love, care, encourage, support, patience in best and worse conditions. My, thanks to my lovely daughters Safa, Amenah, Nusk and Gherked who have suffered the most during my absence in their most needed times. My apology for them. Finally, my deepest thanks and gratitude to my big family, brothers, sisters and my relatives for their helps, supports and prayers. VI TABLE OF CONTENTS Contents DECLARATION ....................................................................................................... III ABSTRACT ................................................................................................................ IV DEDICATION ............................................................................................................. V ACKNOWLEDGEMENTS ....................................................................................... VI TABLE OF CONTENTS ......................................................................................... VII Chapter 1 ...................................................................................................................... 1 1.1 Background ..................................................................................................... 2 1.2 Gasification and biomass gasification ............................................................. 4 1.3 Fluidised Bed Reactors .................................................................................... 7 1.4 Energy in Iraq .................................................................................................. 7 1.5 Iraqi Biomass Energy-Date Palm Wastes ....................................................... 8 1.6 Motivation and Aims ..................................................................................... 11 1.7 Research Hypothesis ..................................................................................... 11 1.8 Layout of the thesis structure ........................................................................ 12 Chapter 2 .................................................................................................................... 14 2.1 Introduction ................................................................................................... 15 2.2 Biomass Gasification Reactions .................................................................... 15 2.2.1 Water-gas reaction (R2.7) ...................................................................... 17 VII 2.2.2 Boudouard reaction (R2.13) ................................................................... 17 2.2.3 Water-gas shift reaction (R2.8) .............................................................. 17 2.2.4 Methanation reaction (R2.12) ................................................................ 17 2.2.5 Steam methane reforming reaction (R2.9) ............................................. 17 2.3 Key factors affecting the gasification process ............................................... 18 2.3.1 Gasifier design ....................................................................................... 18 2.4 Gasification of biomass in the bubbling fluidised bed gasifiers BFBGs ...... 23 2.4.1 Factors affecting biomass gasification process in bubbling fluidised bed gasifiers …………………………………………………………………………24 2.4.2 Hydrodynamic factors ............................................................................ 31 2.5 Fluidisation phenomena and fluidised bed .................................................... 35 2.5.1 Fluidised bed column ............................................................................. 36 2.5.2 Solid particles classification: ................................................................. 37 2.5.3 Types of fluidisations (fluidisation regimes) ......................................... 37 2.5.4 Minimum fluidization velocity and pressure drop ................................. 40 2.5.5 Biomass fluidisation ............................................................................... 44 2.5.6 Parameters affect minimum fluidisation velocity .................................. 47 2.6 Summary ....................................................................................................... 52 Chapter 3 .................................................................................................................... 54 VIII 3.1 Introduction ................................................................................................... 55 3.2 Geometry and hydrodynamic design of the bubbling fluidised bed gasifier. 56 3.2.1 Theoretical model of bubbling fluidising bed reactor ............................ 56 3.2.2 Design equations for the reaction bed section........................................ 57 3.2.3 Freeboard Section................................................................................... 64 3.2.4 Distributor plate and air box section ...................................................... 65 3.3 Rig and gasifier operating flexibility ............................................................. 68 3.3.1 Design procedure and design steps ........................................................ 69 3.3.2 Design Results ........................................................................................ 72 3.3.3 Summary of the flexible design and geometry parameters of the gasifier 76 3.4 Summary ....................................................................................................... 79 Chapter 4 .................................................................................................................... 80 4.1 Introduction ................................................................................................... 81 4.2 Characterization of quartz sand material ....................................................... 81 4.2.1 Sand material preparation ...................................................................... 81 4.3 Characterisation of biomass materials ........................................................... 87 4.3.1 Sample preparation................................................................................. 87 4.3.2 The composition analysis of biomass solid fuels ................................... 93 IX 4.4 Cold rig prepared materials ......................................................................... 101 4.4.1 Fluidised bed cold column (transparent pipe) ...................................... 101 4.4.2 Air flow-box pipe section..................................................................... 103 4.4.3 Stainless steel flanges ........................................................................... 104 4.4.4 Perforated Distributor Plate ................................................................. 104 4.4.5 Air flow measurements ........................................................................ 105 4.4.6 Air pressure regulator control .............................................................. 106 4.4.7 Pressure drop device (Manometer) ...................................................... 106 4.5 Hot rig prepared materials ........................................................................... 107 4.5.1 The pipe of fluidised bed reaction section ........................................... 107 4.5.2 Freeboard pipe section- second part ..................................................... 108 4.6 Summary ..................................................................................................... 109 Chapter 5 .................................................................................................................. 110 5.1 Introduction ................................................................................................. 111 5.2 Cold experiment rig hardware ..................................................................... 111 5.2.1 Feed air pressure regulator ................................................................... 112 5.2.2 Rotameters............................................................................................ 113 5.2.3 Bubbling fluidised bed column ............................................................ 113 X