gasification technologies a primer for engineers and scientists

Gasification Technologies A Primer for Engineers and Scientists John Rezaiyan Nicholas P. Cheremisinoff Copyright © 2005 Taylor & Francis Group, LLC The source for the cover picture is the U.S. Department of Energy, National Energy Technology Laboratory’s Web site: http://www.netl.doe.gov/cctc/resources/database/photos/phototampa.htm Published in 2005 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2005 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10987654321 International Standard Book Number-10: 0-8247-2247-7 (Hardcover) International Standard Book Number-13: 978-0-8247-2247-0 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. 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Dk3024_Discl Page 1 Monday, March 7, 2005 10:40 AM Copyright © 2005 Taylor & Francis Group, LLC Table of Contents Chapter 1 Principles of Gasification 1 Introduction 1 Historical Perspective and Commercialization Trends 2 Historical Perspectives 2 Renewed Interest and the Incentives for Commercialization 3 Commercialization Growth and Today’s Applications 4 Gasification Principles 5 Overview 5 Hydrogenation 7 Stoichiometric Considerations 7 Gasification Versus Combustion 10 Comparisons of General Features 10 Environmental Controls 10 Solid Byproducts 13 Advantages of Gasification over Combustion 14 Stoichiometries and Thermodynamics 16 Drying 17 Devolatilization 17 Gasification 17 Combustion 18 DK3024_C000.fm Page xiii Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC xiv Rezaiyan and Cheremisinoff Gasification Kinetics 20 Biomass Gasification 23 Overview 23 Types of Biomass Gasifiers 24 Biomass Characteristics 25 Petroleum Coke Gasification 27 References 30 Recommended Resources 32 Chapter 2 Coal Gasification Technologies 35 Introduction 35 Coal Gasification 36 Overview 36 Types of Coal 36 Composition and Structure 38 Characteristics 39 Gasifier Configurations 40 Gasifier Classification 40 Entrained Flow Technologies 41 Fluidized-bed Technologies 54 Moving-bed Technologies 62 Technology Suppliers 64 Syngas Characteristics 64 Gas Cleanup Systems 65 Technology Suppliers for Particulate Removal 67 Sulfur Removal 67 The Power Block 68 Comparisons Between Technologies 68 Syngas Applications and Technology Selection Criteria 68 Integrated Gasification Combined Cycle 81 Operational Feedback 85 Investment Costs 86 Guide to Commercial Experience 86 Chapter 3 Biogasification 119 Introduction 119 Overview 119 Technology Advantages 120 General Applications 121 Commercial Systems 121 DK3024_C000.fm Page xiv Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC Table of Contents xv Contaminants 127 Formation of Tars 130 Ammonia Formation 131 No X Formation 132 Sulfur 132 Hydrogen Production from Biomass 133 Recommended Resources 140 EndNotes 143 Chapter 4 Pyrolysis 145 Introduction 145 Pyrolysis Principles 147 General 147 Effect of Heating Rate 149 Effect of Temperature 150 Applications 152 Large-scale Commercial Processes for Mixed Solid Waste 152 Application to Contaminated Soil Remediation 157 Treatment of Municipal Solid Waste 158 Treatment of Medical Waste 159 Plasma Torches and Plasma Pyrolysis 160 EndNotes 164 Chapter 5 Gas Cleanup Technologies 165 Introduction 165 Overview of Particulate Removal Technologies 165 Particulate Collection Technologies 170 Gravity Settling Chambers 170 Cyclone Separators 177 Fabric Filter Pulse Jet-Cleaned Type 185 Dry Electrostatic Precipitator: Wire-Pipe Type 193 Wet Electrostatic Precipitator: Wire-Pipe Type and Others 200 Venturi Scrubbers 208 Orifice Scrubber 214 Condensation Scrubbers 219 Gas Conditioning Technologies 221 Packed Tower and Absorption 222 Impingement-Plate/Tray Tower Scrubbers 231 Fiber-Bed Scrubbers 236 DK3024_C000.fm Page xv Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC xvi Rezaiyan and Cheremisinoff Activated Carbon and Other Adsorber Systems 239 Thermal Destructive Technologies 247 Recommended Resources 265 Chapter 6 Integration of Gasification Technologies 271 Introduction 271 Role of Coal Gasification 271 Gas Turbine Technologies 282 Fuel Requirements 286 Use of Coal-Derived Liquid Fuel 287 Market Trends 289 R&D Needs 294 Improved Operational Performance 294 Improved Efficiencies 294 Fuel Cell Technology Development Status 298 Integrated Gasification Fuel Cell Power Systems Requirements 305 Integrated Gasification Fuel Cell Hybrid Power Systems Requirements 307 System Configurations and Costs 309 Fuel Processing Technology 313 Technology Integration with Coal Gasification 313 Hybrid Systems 315 Fuel Cell Technology and System Integration Issues 317 Areas for Technical Development 318 Large-Scale Distributed Power, Industrial Cogeneration, and Central Generation 319 Gasification Technology Development and System Integration Issues 320 Recommended Resources 328 DK3024_C000.fm Page xvi Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC xvii Preface Gasification technologies offer the potential of clean and efficient energy. The technologies enable the production of synthetic gas from low or negative-value carbon-based feedstocks such as coal, petro- leum coke, high sulfur fuel oil, materials that would otherwise be disposed as waste, and biomass. The gas can be used in place of natural gas to generate electricity, or as a basic raw material to produce chemicals and liquid fuels. Gasification is a process that uses heat, pressure, and steam to convert materials directly into a gas composed primarily of carbon monoxide and hydrogen. Gasification technologies differ in many aspects but rely on four key engineering factors: 1. Gasification reactor atmosphere (level of oxygen or air content) 2. Reactor design 3. Internal and external heating 4. Operating temperature The feedstock is prepared and fed, in either dry or slurried form, into a reactor chamber called a gasifier. The feedstock is subjected DK3024_C000.fm Page xvii Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC xviii Rezaiyan and Cheremisinoff to heat, pressure, and either an oxygen-rich or oxygen-starved envi- ronment within the gasifier. All commercial gasifiers require an energy source to generate heat and begin processing. There are three primary products from gasification: • Hydrocarbon gases (also called syngas) • Hydrocarbon liquids (oils) • Char (carbon black and ash) Syngas can be used as a fuel to generate electricity or steam, or as a basic building block for a multitude of chemicals. When mixed with air, syngas can be used in gasoline or diesel engines with few modifications to the engine. Both pyrolysis and gasification convert carbonaceous materials into energy-rich fuels by heating the feedstock under controlled conditions. Whereas incineration fully converts the input material into energy and ash, these processes deliberately limit the conver- sion so that combustion does not take place directly. Instead, they convert the material into valuable intermediates that can be further processed for materials recycling or energy recovery. Gasification in particular offers more scope for recovering prod- ucts from waste than incineration. When waste is burned in a modern incinerator the only practical product is energy, whereas the gases, oils, and solid char from gasification can not only be used as a fuel but also be purified and used as a feedstock for petro-chemicals and other applications. Gasification can be used in conjunction with gas engines and gas turbines to obtain higher conversion efficiency than conventional fossil-fuel electric power generation. In contrast, con- ventional incineration, used in conjunction with steam-cycle boilers and turbine generators, achieves lower efficiency. Gasification can help meet renewable energy steam targets, address concerns about global warming, and contribute to achieving Kyoto Protocol commitments. There are more than 150 companies around the world that are marketing systems based on gasification concepts. Many of these are optimized for specific wastes or particular scales of dedicated energy production operations. They vary widely in the extent to which they are proven in operation. In addition, there are more than 100 facilities operating around the world. This book serves as a primer to coal and biomass gasification technologies. It is meant as an introduction and overview of current technology developments, and to provide readers with a general DK3024_C000.fm Page xviii Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC Preface xix understanding of the technology challenges for large-scale commer- cialization. While there is an abundant source of literature both on the World Wide Web and in printed form, the information and experiences in development and commercialization are fragmented. This volume helps to place the technology and research and devel- opment challenges into perspective. Nicholas P. Cheremisinoff, Ph.D. A. John Rezaiyan Princeton Energy Resources International, LLC DK3024_C000.fm Page xix Friday, March 4, 2005 3:58 PM Copyright © 2005 Taylor & Francis Group, LLC xxi About The Authors Nicholas P. Cheremisinoff has 30 years of industry and applied research and development experience throughout the petrochemical and allied industries. His assignments have focused on implemen- tation of clean technologies for manufacturing and energy production, with experiences ranging from fossil energy to biomass and wind energy applications. He has worked extensively on overseas assign- ments for donor agencies such as the United States Agency for International Development, for international lending institutions including the World Bank Organization, and for numerous private sector clients. He is the author, co-author, or editor of more than 100 technical books. Dr. Cheremisinoff received his B.Sc., M.Sc., and Ph.D. degrees in chemical engineering from Clarkson College of Technology. A. John Rezaiyan is Vice President for Advanced Engineering Group at Princeton Energy Resources International LLC (PERI). He has 25 years of experience in fluidized-bed combustion and gasification technology development. He works closely with technology developers, project developers, government agencies, and financial institutions to assess market potential and technical, economic, and DK3024_C000.fm Page xxi Tuesday, March 8, 2005 3:15 PM Copyright © 2005 Taylor & Francis Group, LLC [...]... gasification systems are generally estimated using thermodynamic data (standard free energies of formation or standard enthalpies and entropies) for formation of pure reactants and products and simplified systems The thermodynamic data for pure reactants and products of gasification systems can be found in a variety of tabulations and correlations.15 Elliot,16 Probstein and Hicks, and Klass present equilibrium... DK3024_book.fm  Page 6  Thursday, January 20, 2005  3:42 PM 6 Rezaiyan and Cheremisinoff Contaminants Gasification Steam Air Gasification Steam Feed Oxygen Gasification Steam Heat Hydrogasification Hydrogen Heat Catalytic Gasification Purification CO, H2, N2 Low-Btu Gas Contaminants Purification CO, H2 Medium-Btu Gas Contaminants Purification CO, H2 Medium-Btu Gas Contaminants CO, H2, CH4 Purification High-Btu Gas Contaminants Purification & Separation CH4... biomass and the char and to distribute the heat Using sand as a heat carrier keeps out the air This results in a better quality fuel gas A second reactor combusts the char to heat the sand Remaining traces of condensable matter formed during gasification are removed in a chamber where a catalyst “cracks” and converts them into fuel gas The clean biogas is then pressurized before it reaches the gas turbine... reactions and govern the overall conversion reactions in coal and biomass gasification processes These char-gas phase reactions are the Boudourd reaction (reaction 6), water-gas reactions (reactions 4 and 5), and hydro-gasification reaction (reaction 7), which is very slow except at high pressures, and methanation reaction (reaction 10), which is very slow relative to water-gas reactions unless catalyzed... non-hazardous and can be used as an admix for road construction material or abrasive material for sand blasting It can also be disposed of as non-hazardous waste Depending on its composition it could also be sold for recovery of valuable metals The primary solid byproduct of combustion processes is bottom ash, which primarily consists of mineral matter and minor amounts of unreacted carbon Because... ash Low temperature processes produce a char that can be sold as fuel Bottom ash and fly ash are collected, treated, and disposed as hazardous waste in most cases High temperature processes produce a slag, a non-leachable, non-hazardous material suitable for use as construction materials Copyright © 2005 Taylor & Francis Group, LLC DK3024_book.fm  Page 12  Thursday, January 20, 2005  3:42 PM 12 Rezaiyan... GASIFICATION VERSUS COMBUSTION Comparisons of General Features Gasification is not an incineration or combustion process Rather, it is a conversion process that produces more valuable and useful products from carbonaceous material Table 1.1 compares the general features of gasification and combustion technologies Both gasification and combustion processes convert carbonaceous material to gases Gasification... indirect hydrogenation process that is still under development is catalytic gasification In this process, a catalyst accelerates the gasification reactions, resulting in the formation of hydrogen and CO, at relatively low temperatures This process also promotes catalytic formation of methane at the same low temperature within the same reactor Catalyst deactivation and costs have been a major impediment... Btu/ft3) can also be used as fuel gas for gas turbines in IGCC applications, for SNG and hydrogen production, for fuel cell feed, and for chemical and fuel synthesis However, it does not require as much upgrading and methanation to produce SNG • SNG (over 35 MJ/m3 or 940 Btu/ft3) can be easily substituted for natural gas and therefore is suitable for hydrogen and chemical production as well as fuel cell... Maximum concentration of H2 and CO can be obtained at atmospheric pressure and temperature range of 800 to 1000°C • CO2 concentration increases with increasing pressures and decreases sharply with increasing temperatures • Reducing oxygen-to-steam ratio of reactant gases (or reactor inlet streams) increases H2 and CH4 formation, while increasing the oxygen-to-steam ratio will increase CO and CO2 formation . Air Steam Steam Steam Oxygen Heat Hydrogen Heat Gasification Gasification Hydro- gasification Catalytic Gasification Feed Contaminants Contaminants Contaminants Contaminants Contaminants Purification Purification Purification Purification Purification. product stream that has higher hydrogen content than the original carbonaceous feed material. Figure 1.1 Gasification methods. Gasification Steam Air Steam Steam Steam Oxygen Heat Hydrogen Heat Gasification Gasification Hydro- gasification Catalytic Gasification Feed Contaminants Contaminants Contaminants Contaminants Contaminants Purification Purification Purification Purification Purification. drive gasification reactions (4) through (9). Reactions (4) and (5), which are known as water-gas reactions, are the principal gasification reactions, are endot- hermic, and favor high temperatures and