Handbook Of Biomass Downdraft Gasifier Engine Systems Ebook - The best free software for your2/25/2018 ![]() ![]() ![]() ![]() A Division of Midwest Research Institute Operated for the U.S. Department of Energy Handbook of Biomass Downdraft Gasifier Engine Systems SERIISP-271-3022 DE88001135 March 1988 UC Category.' 245 This handbook has been prepared by the Solar Energy Research Institute under the U.S. Ebook Pdf handbook of biomass downdraft gasifier engine systems Verified Book Library Ebook Pdf handbook of biomass downdraft gasifier engine systems Verified Book. Bailie, R.C., Current Developments and Problems in Biomass Gasification Sixth Annual Meeting Biomass Energy Institute, Winnipeg, Manitoba, canada, October, 1977. Calvert, Seymour, et al., Wet Scrubber System Study, Volume I: Scrubber Handbook, U.S. Department of commerce, Ntis PB-213 016, August, 1972. Beat power outages. Never pay for power again! Turn dry wood into free off-grid generator fuel in minutes. Premium wood gasifier plans starting at $65. ![]() Department of Energy Solar Technical Information Program. It is intended as a guide to the design, testing, operation, and manufacture of small-scale [less than 200 kW (270 hpJ] gasifiers. A great deal of the information will be useful for all levels of biomass gasification. The handbook is meant to be a practical guide to gasifier systems, and a minimum amount of space is devoted to questions of more theoretical interest. We apologize in advance for mixing English and Scientifique Internationale (SI) units. Whenever possible, we have used SI units, with the corresponding English units fol lowing in parentheses. Unfortunately, many of the figures use English units, and it would have been too difficult to convert all of these figures to both units. We have sup plied a conversion chart in the Appendix to make these conversions easier for the reader. Bill Nostrand, one of our very helpful reviewers, died in May 1985. Bill was num ber one in the ranks of those who became interested in gasification because of its poten tial for supplying clean, renewable energy. We all will miss him. The improvement of gasification systems will be noticeably slowed by his death. We dedicate this book to the Bill Nostrands of this world who will bring gasifier systems to the level of safety, cleanliness, and reliability required to realize their full potential. Thanks, Bill. Das Golden, Colorado A Product of the Solar Technical Information Program Solar Energy Research Institute 1 617 Cole Boulevard, Golden, Colorado.. _____________ Whole system __________ --,l. Acknowledgments Since it is impossible for one or two authors to realistically comprehend a subject from all viewpoints, we have solicited input from leading workers in the field. Early versions were sent to a number of investigators, and each was invited to comment on and supplement our effort. We therefore express our heartfelt thanks to the following reviewers for greatly enhancing the quality of the final product: Dr. Thomas Milne, Solar Energy Research Institute Dr. Bjorn Kjellstrom, The Beijer Institute, Sweden Dr. Thomas McGowan, Georgia Institute of Technology Mr. Matthew Mendis, World Bank Dr. Hubert Stassen, Twente University, The Netherlands Prof. Ibarra Cruz, University of Manila, The Philippines Mr. Bill Nostrand, New England Gasification Associates We take final responsibility for the contents and omissions, and extend our apologies to those workers whose work we may have unknowingly omitted. Organization and Use A gasifier converts solid fuel to gaseous fuel. A gasifier system includes the gasification reactor itself, along with the auxiliary equipment necessary to handle the solids, gases, and effluents going into or coming from the gasifier. The figure below shows the major components of a gasifier system and the chapters in which they are discussed. Fuel Ch.3 Gasifier Ch.4, 5, 6 Gas measurement and cleaning Ch. 7, 8 Engine (or combustor) Ch. 9, 1 0 Notice This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States govern ment nor any agency thereof. Nor any of their employees, makes any warranties, express or implied. Or assumes any legal liability or respon sibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific'commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States govern ment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Printed in the United States of America Available from: Superintendent of Documents U.S. Government Printing Office Washington, DC 20402 National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 Price: Microfiche A01 Printed Copy A07 Codes are used for pricing all publications, The code is determined by the number of pages in the publication, Information pertaining to the pricing codes can be found in the current issue of the following publications which are generally available in most libraries: Energy Research Abstmcts (ERA); Government Reports Announcements and Index (GRA and I) Scientific and Technical Abstmct Reports (STAR); and publica tion NTIS-PR-360 available from NTIS at the above address. 24 Contents 1.0 Introduction and Guide to the Literature and Research 1 1.1 Role of Gasification in Biomass Conversion 1 1.2 Biomass Energy Potential.... 2 1.3 Guide to Gasification Literature 3 1.3.1 Bibliographies..... 3 1.3.2 Books.......... 3 1.3.3 Gasification Proceedings 3 1.3.4 Commercial Information 4 1.3.5 Producer Gas Research 4 1.3.6 Producer Gas R&D Funding 4 1.3.7 Federal Emergency Management Agency (FEMA) Gasifier Work 4 2.0 History, Current Developments, and Future Directions 6 2.1 Historical Development........... 6 2.1.1 Early Development of Gasification 6 2.1.2 Vehicle Gasifiers.... 6 2.2 Current Development Activities 7 2.3 Future Development Directions 7 3.0 Gasifier Fuels 9 3.1 Introduction...... 9 3.2 Biomass Fuel Analysis 9 3.2.1 Proximate and Ultimate Analysis 9 3.2.2 Physical Tests...... 12 3.3 Other Fuel Parameters. 12 3.3.1 Particle Size and Shape. 12 3.3.2 Charcoal and Char Properties. 13 3.3.3 Biomass Ash Content and Effects. 15 3.3.4 Biomass Moisture Content and Effects. 16.3.3.5 Biomass Heating Value 16. 19 3.4 Beneficiation of Biomass Fuels.. 3.4.1 Densifying Biomass Fuels 3.4.2 Drying Biomass Fuels 3.5 Biomass Fuel Emissions 4.0 Principles of Gasification. 21 4.1 Introduction....... 21 4.2 Biomass Thermal Conversion Processes. 21 4.2.1 Introduction...... 21 4.2.2 Biomass Pyrolysis 4.2.3 Combustion of Biomass........... 4.2.4 Chemistry of Biomass Gasification 4.2.5 Thermodynamics of Gasification.. 25 Contents iii. 24 4.3 Indirect and Direct Gasification Processes. 25 4.3.1 Indirect (Pyrolitic) Gasification.. 25 4.3.2 Direct Gasification......... 25 4.4 Principles of Operation of Direct Gasifiers. 27 4.4.1 Introduction. 27 4.4.2 Operation of the Updraft Gasifier. 27 4.4.3 Operation of the Downdraft Gasifier. 28 4.4.4 Factors Controlling Stability of Gasifier Operation. 28 4.5 Charcoal Gasification. 28 4.6 Summary.. 29 5.0 Gasifier Designs. 30 5.1 Introduction. 30 5.2 Basic Gasifier Types. 30 5.3 Charcoal Gasifiers... 31 5.4 Charcoal versus Biomass Fuels. 31 5.5 The Crossdraft Gasifier..... 32 5.6 The Updraft Gasifier...... 32 5.7 The Imbert Downdraft Gasifier. 32 5.7.1 Introduction...... 32 5.7.2 Description of the Downdraft (Imbert) Gasifier. 33 5.7.3 Superficial Velocity, Hearth Load, and Gasifier Sizing. 35 5.7.4 Turndown Ratio........... 36 5.7.5 Disadvantages of the Imbert Design. 36 5.8 The Stratified Downdraft Gasifier...... 38 5.8.1 Introduction............. 38 5.8.2 Description of the Stratified Downdraft Gasifier. 38 5.8.3 Unanswered Questions About the Stratified Downdraft Gasifier. 40 5.8.4 Modeling the Stratified Downdraft Gasifier. 42 5.9 Tar-Cracking Gasifiers. 42 5.9.1 Introduction...... 42 5.9.2 Combustion of Tars. 43 5.9.3 Thermal Tar Cracking. 45 5.9.4 Catalytic Tar Cracking. 46 5.10 Summary............ 46 6.0 Gasifier Fabrication and Manufacture. 48 6.1 Introduction........ 48 6.2 Materials of Construction..... 48 6.3 Methods of Construction..... 48 6.4 Sizing and Laying out the Pipes. 49 6.5 Instruments and Controls. 49 6.5.1 Temperature. 49 6.5.2 Pressure. 49 6.5.3 Gas Mixture. 49 6.5.4 Automatic Controls. 49 Handbook of Biomass Downdraft Gasifier Engine Systems iv. 74 7.0 Gas Testing. 51 7.1 Introduction.................... 51 7.2 Gas-Quality Measurements and Requirements. 51 7.3 Description of Producer Gas and Its Contaminants. 51 7.3.1 The Gas Analysis. 51 7.3.2 Particulates. 51 7.3.3 Tars...... 55 7.4 Gas Sampling..... 55 7.4.1 Sample Ports. 55 7.4.2 Isokinetic Sampling. 56 7.5 Physical Gas-Composition Testing. 57 7.5.1 Raw Gas...... 57 7.5.2 Cleaned Gas. 61 7.6 Chemical Gas Composition. 61 7.6.1 Gas Samples for Chemical Analysis. 61 7.6.2 Methods of Analysis.. 62 7.6.3 Water Vapor Analysis......... 65 7.7 Analysis of Test Data.............. 66 7.7.1 Mass Balances and Energy Balances. 66 7.7.2 Flow Rate Characterization..... 67 7.8 Particle-Size Measurement.......... 67 7.8.1 Typical Particle-Size Distributions. 67 7.8.2 Sieve Analysis........ 67 7.8.3 Microscopic Size Analysis. 67 7.8.4 Aerodynamic Size Analysis. 67 7.8.5 Graphic Analysis of Size Distribution. 69 7.8.6 Physical Size Analysis. 70 8.0 Gas Cleaning and Conditioning. 71 8.1 Introduction........... 71 8.2 The Power Theory of Gas Cleanup. 72 8.3 Gas Cleanup Goals......... 74 8.3.1 Gas Contaminant Characteristics. 74 8.3.2 Typical Dirty Gas. 74 8.3.3 Gas Cleanup Goals... 74 8.3.4 Cleanup Design Target 8.4 Classification of Particles.... 74 8.5 Particle Movement and Capture Mechanisms. 74 8.6 Dry Collectors............ 75 8.6.1 Gravity Settling Chambers. 75 8.6.2 Cyclone Separators. 75 8.6.3 Baghouse Filter. 80 8.6.4 Electrostatic (Cottrell) Precipitators. 83 8.7 Wet Scrubbers............. 84 8.7.1 Principles of Wet Scrubbers. 84 8.7.2 Scrubber Equipment.. 86 8.7.3 Auxiliary Equipment. 88 Contents v 8.8 Disposal of Captured Contaminants. 92 8.8.1 Char-Ash.. 92 8.8.2 Tar..... 92 8.8.3 Condensate. 92 9.0 Gasifier Systems. 93 9.1 The Complete Gasifier System. 93 9.2 Storing, Feeding, and Sealing Solids. 93 9.2.1 Characteristics of Solids. 93 9.2.2 Storage........ 93 9.2.3 Feeding Solids...... 94 9.2.4 Sealing Solid Flows... 94 9.3 Fans, Blowers, Ejectors, and Compressors. 95 9.3.1 Importance of Gas-Moving System Design. 95 9.3.2 Fans. 95 9.3.3 Blowers. 96 9.3.4 Ejectors.. 96 9.3.5 Turbochargers and Superchargers. 97 9.4 Flares and Product-Gas Burners. 97 9.4.1 Flares.. 97 9.4.2 Burners....... 98 1 0.0 Instrumentation and Control. 99 10.1 The Need for Instruroentation and Control. 99 10.2 Gasifier Instruroents........ 99 10.2.1 Pressure Measurement... 99 10.2.2 Gas Flow Measurement 100 10.2.3 Solid Flow Measurement 103 10.2.4 Temperature Measurements 103 10.3 Controls........... 103 10.3.1 Fuel-Level Controls 103 10.3.2 Pressure Controls.. 103 10.3.3 Temperature Controls 104 10.4 Computer Data Logging and Control 104 1 1.0 Engine Adaptation and Operation 105 11.1 Introduction........... 105 11.2 Producer Gas for Transportation 105 11.3 Producer Gas for Electric Power and Irrigation 105 11.4 Gasifier Types Suitable for Shaft-Power Generation 105 11.5 Sizing the Gas Producer to the Engine....... 105 11.6 Engine Selection................... 106 11.6.1 Large-Vehicle Engines - Truck Engines up to 50 kW 106 11.6.2 Small Engines 106 11.6.3 Natural-Gas Engines 106 11.6.4 Diesel Engines 106 11.7 Cogeneration......... 106 Handbook of Biomass Downdraft Gasifier Engine Systems vi 11.8 Spark-Ignition Engine Conversion 11.8.1 Engine System 11.8.2 Gas Mixers 11.8.3 Power Time Lag 11.8.4 Engine Startup 11.8.5 Ignition Timing 11.8.6 Spark Plugs.. 11.9 Two-Cycle Engine Conversion 11.10 Diesel Engine Conversion.. 11.10.1 Diesel Operation with Producer Gas 11.10.2 Starting Diesel Engines....... 11.10.3 Throttling at Partial Load...... 11.11 Increasing Power from Producer-Gas-Fueled Engines 11.11.1 Mechanisms of Power Loss 11.11.2 Engine Breathing..... ' 11.11.3 Efficiency and Power Loss 11.11.4 Blowers and Superchargers 11.11.5 Other Methods for Increasing Producer Gas Power 11.12 Engine Life and Engine Wear 11.12.1 Engine Life Expectancy....... 11.12.2 Sticking Intake Valves....... 11.12.3 Oil Thickening and Contamination 11.12.4 Tar/Oil Accumulations 11.12.5 Engine Corrosion 11.12.6 Engine Warranty 11.13 Exhaust Emissions.... 11.14 Other Devices for Producer-Gas Power Generation 11.14.1 Gas Turbines.......... 11.14.2 Fuel Cells........... 11.14.3 External-Combustion Devices 1 2.0 Safety and Environmental Considerations 12.1 Introduction....... 12.2 Toxic Hazards...... 12.2.1 Carbon Monoxide 12.2.2 Creosote.... 12.3 Fire Hazards...... 12.4 Environmental Hazards 13.0 Decision Making..... 13.1 Introduction..... 13.2 Logistics Assessment 13.2.1 Gasifier Application 13.2.2 Equipment Selection Factors 13.2.3 Feedstock Supply 13.2.4 Regulations......... 13.2.5 Labor Needs........ 13.2.6 Final Logistics Considerations. 124 Contents vii 13.3 Economics............ 125 13.3.1 Costs.......... 125 13.3.2 Calculating Energy Costs 125 13.3.3 Equipment Cost 126 13.3.4 Conversion Efficiency and Fuel Consumption 127 13.3.5 The Cost of Operating Labor 127 13.3.6 Maintenance Costs.... 127 13.4 Cost Benefits............ 128 13.4.1 Value of Power Produced 128 13.4.2 Cogeneration Possibilities 129 13.5 Financing............. 129 13.5.1 Government Subsidies in the Form of Tax Incentives 129 13.5.2 Financial Institutions 129 13.6 Other Considerations 129 References 131 Appendix. 139 viii Handbook of Biomass Downdraft Gasifier Engine Systems Chapter 1 Introduction and Guide to the Literature and Research 1.1 Role of Gasification in Biomass Conversion This handbook explains how biomass can be converted to a gas in a downdraft gasifier and gives details for designing, testing, operating, and manufacturing gasifiers and gasifier systems, primarily for shaft power generation up to 200 kW. It is intended to help convert gasification from a practical art into a field of en gineered design. Although the handbook focuses on downdraft gasification as the only method suitable for small-scale power systems, it also gives extensive detail on biomass fuels, gas testing and cleanup in strumentation, and safety considerations that will be of use to all those who work with gasifiers at whatever scale. The combustion of biomass in wood stoves and in dustrial boilers has increased dramatically in some areas, and forest, agricultural, and paper wastes are being used extensively for fuels by some industries. However, more extensive biomass use still waits for the application of improved conversion methods, such as gasification, that match biomass energy to processes currently requiring liquid and gaseous fuels. Examples of s uch processes include glass, lime, and brick manufacture; power generation; and transportation. Biomass, like coal, is a solid fuel and thus is inherent ly less convenient to use than the gaseous or liquid fuels to which we have become accustomed. An over view of various processes now in use or under evalua tion for converting biomass to more conventional energy forms such as gas or liquid fuels is shown in Fig. 1-1 (Reed 1978). The figure shows how sunlight is converted to biomass through either traditional ac tivities (e.g., agriculture and silviculture) or new in novative techniques (e.g., as energy plantations, coppicing, and algaeculture) now being developed. Biomass resources fall into two categories: wet or wet table biomass (molasses, starches, and manures) and dry biomass (woody and agricultural materials and residues). Biological processes require wet biomass and operate at or near room temperature. These proces ses, shown on the lower left side of Fig. '1-1, include fermentation to produce alcohols and digestion to produce methane. Thermal processes function best using biomass feedstocks with less than 50% moisture content and are shown on the right side of Fig. The simplest thermal process is combustion, which yields only heat. Pyrolysis uses heat to break down biomass and yields charcoal, wood-oils, tars, and gases. Gasification processes convert biomass into combus tible gases that ideally contain all the energy original ly present in the biomass. In practice, gasification can convert 60% to 90% of the energy in the biomass into energy in the gas. Gasification processes can be either direct (using air or oxygen to generate heat through ex othermic reactions) or indirect (transferring heat to the reactor from the outside). The gas can be burned to produce industrial or residential heat, to run engines for mechanical or electrical power, orto make synthetic fuels. In one sense, biomass gasification is already a well proven technology. Approximately one million downdraft gasifiers were used to operate cars, trucks, boats, trains, and electric generators in Europe during World War II (Egloff 1943), and the history of this ex perience is outlined in Chapter 2. However, the war's end saw this emergency measure abandoned, as inexpensive gasoline became available (Reed 1985b). Development of biomass gasification was disrupted in 1946 as the war ended and inexpensive (15¢/gal) gasoline became available. The magnitude of damage inflicted on gasifier technology by this disruption Can be seen by the fact that it is difficult for even the 'ad vanced' technology of the 1980s to achieve on tests what was routine operation in the 1940s. The design, research, and manufacturing teams of that decade have all disbanded. We have from the past only that small fraction of knowledge that has been published, whereas the large bulk of firsthand experience in operation design has been lost and forgotten. Gasification was rediscovered in an era of fuel shortages and higher oil prices, and there are gasifier engine projects under way in more than 20 countries for producing process heat and electrical and mechani cal power (Kjellstrom 1983, 1985). In its rebirth, however, the existing technology has uncovered major problems in connection with effluent and gas cleanup and the fuel supply, which were less important during the emergency of World War II. Today, these problems must be solved if biomass gasification is to reemerge a a fuel source. Apparently, it is going to take a few years for the technology of the 1980s to be effectively applied to the accomplishments of the 1940s. Space-age advan ces in materials and control systems are available for Introduction and Guide to the Literature and Research J ' /sunligh L I I 1-1 I L wastes t- J I r I I I I I I 1-------1 I f{ Air I L-___ ---I I LO';;a tu I fJxygent- I I I I I I use in today's process designs, so a continuous development effort and lively open exchange should enable us to incorporate latter-day chemical and chemical engineering techniques to build clean, con venient, and reliable systems. A recent workshop on low-energy gasification tabulates research and development needs (Easterling 1985). The accelerated use of gasification technologies ul timately depends upon their ability to compete with fossil fuels, which in turn depends on unknown factors about resources, economics, and political conditions. At present (1988), gasification and other alternative energy processes are being developed slowly in the United States because of relatively plentiful supplies of low-cost gaseous and liquid fossil fuels. However, political changes could rapidly and dramatically alter this situation, as witnessed during the OPEC oil crises of the seventies. Office of Technology Assess ment (OTA) recently has issued a report calling for a national capability for emergency implementation of gasifiers (OTA 1984). 1.2 Biomass Energy Potential Biomass is a renewable fuel that supplies 2% to 3% of U.S. Energy needs and an even larger percentage in some other countries (OTA 1980; DOE 1982). OTA projects that biomass could supply from 7% to 20% (6 17 quads*) annually (OTA 1980) from sources such as those shown in Table 1-1 (Reed 1981), if it can be made available in a convenient form and if conversion equip ment is accessible. The potential of biomass for world use is equally great (Bioenergy 1985). Important: This is a book-sized document that may require significant time to download and display on your monitor. In fact, the total download time may be measured in minutes, depending on the speed of your Internet connection. The best viewing experience can be had by right-clicking and saving this resource as a local file for offline access. Description Handbook of Biomass Downdraft Gasifier Engine Systems, Second Edition — a 156-page document by Thomas B. Reed and Agua Das — is made available here from the archives of the former Biomass Energy Foundation (BEF). Over a million wood gasifiers were used to power cars and trucks during World War II. Yet, there are now only a few companies manufacturing gasifier systems. In this “new Testament” of gasification, Reed and Das, who have spent more than 20 years working with various gasifier systems, discuss the factors that must be correct to have a successful “gasifier power system.” This publication was originally sold by the Biomass Energy Foundation (BEF) for $35. Dr TLUD and staff would like to thank Dr. Reed for making this publication available for free distribution. (SERI-1988) ISBN 1-890607-00-2 Note: This document is a PDF file produced by optically scanning a paper copy. Since it is not derived from a native word-processing format, pages may appear out-of-alignment and/or oddly ordered (as for book binding). This is the best copy we can provide at this time. Resource Last Updated: 29 September 1998.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
March 2018
Categories |