Power Systems For further volumes: http://www.springer.com/series/4622 Hartmut Spliethoff Power Generation from Solid Fuels 123 Dr. Hartmut Spliethoff TU Munchen¨ Institut fur¨ Energiewirtschaft und Anwendungstechnik Arcisstrasse 21 80333 Munchen¨ Germany [email protected] ISSN 1612-1287 ISBN 978-3-642-02855-7 e-ISBN 978-3-642-02856-4 DOI 10.1007/978-3-642-02856-4 Springer Heidelberg Dordrecht London New York Library of Congress Control Number: 2009942919 c Springer-Verlag Berlin Heidelberg 2010 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, Berlin Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Today, fossil fuels dominate worldwide primary energy consumption. In 2000, about 40% of total primary energy was used for electricity generation, and of this, coal was the fuel for 40%, making it the most important primary energy carrier for power production. Forecasts of future energy consumption predict a further increase of worldwide coal utilisation in the coming 20 years. In comparison to natural gas and oil, coal has the advantage of being the most abundant fossil energy carrier. Fossil fuels are the major source of CO2 emissions and cause global warming with all its negative impacts. It is generally accepted today that huge efforts have to be undertaken to limit the emissions of CO2 and to reduce the impact of global warming. Mitigation scenarios indicate that this can only be achieved if all options for CO2 reduction are followed. The principle possibilities for reducing CO2 emis- sions are more efficient energy utilisation, the substitution of fossil fuels by renew- able energies or nuclear energy and carbon capture. It is the intention of the author to explain the technical possibilities for reducing CO2 emissions from solid fuels. The strategies which will be treated in this book are more efficient power and heat generation technologies, processes for the utilisation of renewable solid fuels, such as biomass and waste, and technologies for carbon capture and storage. The book introduces the different technologies to produce heat and power from solid fossil (hard coal, brown coal) and renewable (biomass, waste) fuels, such as combustion and gasification, steam power plants and combined cycles. The technologies are discussed with regard to their efficiency, emissions, operational behaviour, residues and costs. Besides proven state of the art processes, the focus will be on the potential of new technologies currently under development or demon- stration. Chapter 1 gives an overview of current worldwide primary energy consumption and its future development. The impact of CO2 emissions on global warming is summarised and the strategies for CO2 reduction are identified. Chapter 2 deals with the origin and classification of solid fuels. Reserves of solid fossil fuels are indicated and the energy potential of biomass and waste is estimated. The fuel properties are characterised with regard to thermal conversion processes. Chapter 3 provides the thermodynamic fundamentals of the thermal cycles which are required to convert the chemically bound energy of the fuels into power. v vi Preface The focus of Chapter 4 is the technology of the steam power plant, which is the dominant process for power plants. The fundamentals of steam generation are introduced and the design principles of a conventional state-of-the-art steam power plant are explained. In comparison to this reference plant, the different possibilities for efficiency increase and the impact of advanced steam conditions on the steam generator is discussed. A summary of the design data of the most advanced operated power plants in the world is included in the outlook for the further development of steam power plants. Chapter 5 deals with combustion, which is the dominant technology of fuel con- version. Starting from the principles of solid fuel combustion and the fundamentals of pollutant formation, the different combustion technologies of fixed bed, fluidised bed and pulverised fuel combustion are compared. Emission reduction technologies, either primary measures within the combustion process or secondary flue gas clean- ing, are examined. Operational problems such as slagging, fouling and corrosion, which have to be related to ash properties and process conditions and which are of great importance for solid fuel combustion, are discussed. The production of mineral residues is inevitable in solid fuel combustion; the options to use the residues are described. Although the technologies for biomass and waste conversion follow the same principles as for coal, substantial differences arise due to the differing fuel quality and the smaller capacity of such power plants. Therefore, biomass and wastes are treated separately in Chapter 6. Besides biomass combustion, biomass gasification, waste combustion and co-combustion technologies are the focus of this chapter. It explains how ash-related problems in biomass and waste conversion are even more pronounced than for coal and will effect the operation of biomass/waste plants and limit the electrical efficiency. Co-utilisation of biomass in coal-fired power stations is a further process option, and the impact on emissions and operational problems is discussed. Gas turbine-based combined cycles for natural gas offer the highest efficiencies in power generation, of up to about 60%. The focus of Chapter 7 is to show the state of development of combined cycle processes for solid fuels. After describing the technology of natural gas-based combined cycles, the processes, the potentials and the development stages of the integrated gasification combined cycle (IGCC), the combined cycle with pressurised fluidised bed combustion (PFBC), the combined cycle with pressurised pulverised coal combustion (PPCC) and the externally fired combined cycle (EFCC) will be explored. Along with the efficiency increases and the use of renewable energy sources, CO2 capture and storage methods offer a possible means of CO2 reduction in fossil fuel- fired power plants. Chapter 8 gives an overview of the options for CO2 separation, transport and storage for power plants. This book developed over the years of my activities at the University of Stuttgart, the Technical University of Delft and now the Technical University of Munich. Results from various research projects are included in the book. The basis of this book was my habilitation “Combustion of solid fuels”, which was published in 2000 in German. Since that time, a lot of new developments have emerged, while Preface vii other areas within the field have progressed only slightly. This is reflected in the book. I would like to thank all those who provided materials, contributions and com- ments to the different chapters of this book: Dr. Oliver Gohlke, Dr. Michael Muller,¨ Dr. Arnim Wauschkuhn, Mr. Sven Kjaer, Mr. Helmuth Bruggemann,¨ Mr. Kendel, co-workers from my chair Energy Systems at the Technical University of Munich and my colleagues from my former employers the Technical University of Delft and the University of Stuttgart. Furthermore, I would like to thank Herbert Rausch for translations and Patrick Lavery for proofreading. Special thanks go to Mrs. Brigitte Demmel for requesting copyrights and Mrs. Korinna Riechert for drawing figures. Munchen¨ August 2009 Contents 1 Motivation ..................................................... 1 1.1 Primary Energy Consumption and CO2 Emissions................ 1 1.1.1 Development of Primary Energy Consumption inthePast40Years................................... 1 1.1.2 Developments Until 2030 . ........................ 1 1.2 Greenhouse Effect and Impacts on the Climate . ............. 5 1.2.1 Greenhouse Effect . ................................... 6 1.2.2 Impacts.............................................. 8 1.2.3 Scenarios of the World Climate . ........................ 8 1.3 Strategies of CO2 Reduction . ............................... 10 1.3.1 Substitution .......................................... 10 1.3.2 CarbonCaptureandStorage(CCS)...................... 11 1.3.3 EnergySaving........................................ 12 1.3.4 Mitigation Scenarios. ............................... 12 References . ..................................................... 13 2 Solid Fuels ..................................................... 15 2.1 Fossil Fuels . .............................................. 15 2.1.1 Origin and Classification of Coal Types . ............. 15 2.1.2 Composition and Properties of Solid Fuels . ............. 16 2.1.3 Reserves of Solid Fuels . ............................... 25 2.2 Renewable Solid Fuels . ................................... 29 2.2.1 Potential and Current Utilisation . .......................