Biomass Conversion Processes for Energy and Fuels

Biomass Conversion Processes for Energy and Fuels

Edited by

SAMIR S. SOFER University of Oklahoma Norman, Oklahoma

and

OSKAR R. ZABORSKY National Science Foundation Washington, DC

PLENUM PRESS • NEW YORK AND LONDON

Library of Congress Cataloging in Publication Data

Main entry under title:

Biomass conversion processes for energy and fuels.

Bibliography: p. Includes index. 1. Biomass energy. I. Sofer, Samir S. II. Zaborsky, Oskar.

TP360.B587 333.95'3

ISBN 978-1-4757-0303-0 ISBN 978-1-4757-0301-6 (eBook) DOl 10.1007/978-1-4757-0301-6

© 1981 Plenum Press, New York Softcover reprint of the hardcover 1 st edition 1981 A Division of Plenum Publishing Corporation 233 Spring Street, New York, N.Y. 10013

All rights reserved

81-15721 AACR2

No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording, or otherwise, without written permission from the Publisher

Preface

Countless pages have been written on alternative energy sources since the fall of 1973 when our dependence on fossil petroleum resources became a grim reality. One such alternative is the use of biomass for producing energy and liquid and gaseous fuels. The term "biomass" generally refers to renewable organic matter generated by plants through photosynthesis. Thus trees, agri­cultural crops, and aquatic plants are prime sources of biomass. Furthermore, as these sources of biomass are harvested and processed into commercial prod­ucts, residues and wastes are generated. These, together with municipal solid wastes, not only add to the total organic raw material base that can be utilized for energy purposes but they also need to be removed for environmental reasons.

Biomass has been used since antiquity for energy and material needs. In fact, firewood is still one of the most sought-after energy sources in most of the world. Furthermore, wood was still a dominant energy source in the U.S. only a hundred years ago (equal with coal). Currently, biomass contributes about 2 quadrillion Btu (l quad = 1015 Btu) of energy to our total energy consump­tion of about 78 quad. Two quad may not seem large when compared to the contribution made by petroleum (38 quad) or natural gas (20 quad), but bio­mass is nearly comparable to nuclear energy (2.7 quad). Moreover, from sil­vicultural energy farms alone, the contribution from biomass could be as high as 5-10 quad by the end of this century. Without getting involved in contro­versy or perhaps a numbers game as to how much energy can be derived from biomass, one fact is clear. Biomass contributes to our present energy sources and could contribute even more so if appropriate actions are taken now and if a better understanding of its potential, as well as its limitations, is achieved.

This book brings together in one volume a description of the rather diverse elements of biomass sources and the currently more promising conversion pro­cesses for energy and fuels purposes. From the outset, we recognized that many

v

vi Preface

topics would have to be excluded and that no single volume can adequately describe all the current processes being used or proposed. Moreover, the excit­ing developments occurring in research make it extremely difficult to project into the future with any certainty. Clearly, the biomass-to-energy area is sub­ject to change, and many exciting advances in research and development will be made in the next few years. Concurrently, institutional, economic, and political issues need clarification, and sound policies need to be established for developing biomass energy.

This book should be considered as an introductory text to the topics of converting biomass to energy and fuels: namely, biomass sources, conversion processes, and technical and economic considerations. We have emphasized conversion processes, and the book provides chapters on both fundamental principles of the conversion processes and actual conversion systems. A unique feature of the volume is a description of all major conversion processes-direct combustion, thermochemical and biological-in one book. Also, an effort was made to describe the various conversion processes in a consistent format and to provide similar information to the reader so that intelligent comparisons can be made. In particular, we desired to obtain complete mass and energy bal­ances for each conversion system. It is our hope that these chapters provide a beginning to more rigorous energy and mass balance analyses and of their more frequent reporting in the literature.

We express our gratitude to all the authors for their valuable contributions to this complex and, at times, controversial subject. We also thank Ms. Mar­garet Williford and Dr. Nancy Roundy for their able assistance. In particular, Ms. Williford's untiring assistance with the authors was most appreciated.

Samir S. Sofer Norman, Oklahoma

Oskar R. Zaborsky McLean, Virginia

Contents

PART I. BIOMASS SOURCES

1. Residues and Wastes Luis F. Diaz and Clarence G. Golueke

1. Introduction. . ............................ . 2. Municipal Solid Wastes

2.1. Quantity.................. . ........ . 2.2. Characteristics. . ................. . 2.3. Fuel Value. . . . . . . . . . . . . . . . . . . . . . ........... . 2.4. Upgrading the Fuel Value ....................... .

3. Municipal Sewage Sludges ................... . 3.1. Types ................................. . 3.2. Quantities. . ......... . 3.3. Characteristics ............................ . 3.4. Utilization of Sludges.

4. Animal Wastes 4.1. Quantity and Quality .......... . 4.2. Utilization .................................. .

5. Crop Residues .......... . 5.1. Types ...................................... . 5.2. Quantity .................................. . 5.3. Quality ................ . 5.4. Seasonality of Generation. . ............ . 5.5. Location of Residues .................. . 5.6. Other Factors ................................ .

6. Industrial Wastt;s ........................... . 7. Forest Products.

7.1. Logging Residues .......... . 7.2. Residues from Wood Product Manufacturing 7.3. Residues from Pulp and Paper Manufacture

References . . ....................... .

vii

3

3 4 5 6 6 7 8 9 9

10 10 11 11 12 13 14 14 14 15 15 15 16 18 19 20 21 23

viii Contents

2. Agricultural and Forestry Residues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Paul G. Risser

1. Introduction............................................. 25 2. Methods of Data Analysis ................................. 26

2.1. Species Selected for Study and Analytical Rationale ...... 26 2.2. Sources of Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3. Chemical Quality of Agricultural and Forestry Residues . . . . . . . . 38 4. Estimates of Agricultural and Forestry Residues. . . . . . . . . . . . . . . 39

4.1. Regional Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4.2. Seasonal Availability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3. Aquatic Biomass ............................................. 49 Paul G. Risser

1. Introduction............................................. 49 2. Algal Biomass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

2.1. yield.............................................. 50 2.2. Feasibility of Culture Systems . . . . . . . . . . . . . . . . . . . . . . . . . 50

3. Aquatic Macrophyte Biomass .............................. 51 3.1. Yield of Selected Species. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.2. Yield of Marsh Communities. . . . . . . . . . . . . . . . . . . . . . . . . . 53 3.3. Energy Equivalents and Nutrient Contents .............. 53

4. Discussion............................................... 54 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4. Marine Biomass. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Ivan T. Show Jr.

1. Introduction............................................. 57 2. Biological Characteristics of Marine Plants . . . . . . . . . . . . . . . . . . . 58 3. Geographical Distribution of Marine Plants. . . . . . . . . . . . . . . . . . . 61 4. Primary Production. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

4.1. Fundamental Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . 62 4.2. Geographical Distribution of Primary Production . . . . . . . . . 62 4.3. Some Highly Productive Plants. . . . . . . . . . . . . . . . . . . . . . . . 64

5. Chemical Properties of Marine Plants. . . . . . . . . . . . . . . . . . . . . . . . 64 5.1. Inorganic Chemistry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 5.2. Organic Chemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.3. Energy Content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

6. Commercial Culture and Cultivation. . . . . . . . . . . . . . . . . . . . . . . . . 68 7. Utilization of Marine Plants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 8. Relationship of Primary Production and Chemical Composition to

Marine Energy Crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 8.1. Preprocessing....................................... 71 8.2. Processing Byproducts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 8.3. Potential Energy Yield. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

Contents

5. Silvicultural Energy Farms .. Jean Francois Henry

I. Introduction..................... . ....... . 2. The Silvicultural Energy Farm Concept. . . ........ . 3. Conceptual Design and Operation of the Silvicultural Energy

Farm.................... . .................... . 3.1. Energy Farm Design Parameters and Layout. 3.2. Energy Farm Operational and Cost Data

3.2.1. Energy Farm Installation ....... . 3.2.la. Land Acquisition.. . ...... . 3.2.1 b. Land Preparation ........... . 3.2.lc. Work Roads ...................... . 3.2.1 d. Irrigation Systems. . . . .. . ......... . 3.2.le. Planting.

3.2.2. Energy Farm Operation. . ....... . 3.2.2a. Irrigation ....... . 3.2.2b. Fertilization. 3.2.2c. Weed Control .................... . 3.2.2d. Harvesting. 3.2.2e. Transportation ........ . 3.2.2f. Maintenance 3.2.2g. Support Costs

4. Biomass Production Economics 4.1. Biomass Production Costs. 4.2. Production Costs Components ......... .

5. Energy Balance for Biomass Production .......... . 6. The Potential of Silvicultural Energy Farming .. 7. Conclusions ............................. . References .

PART II. CONVERSION PROCESSES Section A. Direct Combustion Processes

6. Basic Principles of Direct Combustion Fred Shafizadeh

I. Introduction .. 2. Composition

2.1. Moisture Content

~'-

2.2. Ash Content. . . ........ . 2.3. Organic Content ............ .

3. Pyrolysis and Heat of Combustion of Biomass and Its Components 4. Combustion Process. References

ix

79

79 80

82 82 83 84 84 85 85 85 86 86 86 86 86 87 88 88 88 88 88 90 91 93 93 94

103

103 104 105 106 106 107 116 124

x

7. The Andco-T orrax System ..

8.

Stanley D. Mark Jr.

1. Introduction ... 2. Description of Process ..

2.1. Gasifier .. 2.2. Fuel Gas System 2.3. Integrated Complete Combustion System.

2.3.1. Gasifier ........ . 2.3.2. Secondary Combustion Chamber ........... . 2.3.3. Regenerative Towers .. 2.3.4. Waste Heat Boiler. 2.3.5. Gas Cleaning System ........... .

3. Review of Plant Operations 3.1. Demonstration Plant. 3.2. Commercial Plants ..

4. Heat and Mass Balances .... 5. Some Applications of the Process ....... .

5.1. Tires, Waste Rubber, and MSW . 5.2. Sewage Sludge and MSW

References ......................... .

Section B. Thermochemical Processes

Basic Principles of Thermochemical Conversion ....... . Stephen M. Kohan

1. Introduction.. . ............ . 2. Kinetics and Thermodynamics Framework.

2.1. Heating Values ....... . 2.2. Standard States ......... . 2.3. Enthalpy Tables ..

3. Gasification of Biomass. 3.1. Types of Gasification Technologies 3.2. Governing Equations. . . . . . . . . . . ............... . 3.3. Downstream Processing ........ .

3.3.1. Gas Purification . . . . . . . . . . . .. . ....... . 3.3.2. Shift Conversion. 3.3.3. Additional Processing ..

3.3.3a. Substitute Natural Gas (SNG) .

Contents

125

125 126 126 127 128 130 130 132 133 133 134 134 134 135 139 141 141 141

145

3.3.3b. Methanol................. . ....... .

145 147 147 147 150 153 153 156 161 161 163 164 164 165 165 166 166 166 169 169 169 170 170

3.3.3c. Ammonia .. 4. Liquefaction of Biomass .

4.1. Types of Liquefaction Technologies .......... . 4.2. Governing Equations. .................. ......... . 4.3. Parallel or Downstream Processing ....... .

4.3.1. Gasification and Recycle. 4.3.2. Solids Removal. . ....... . 4.3.3. Liquid Recovery/Drying ........ .

References ........ .

Contents

9. The Occidental Flash Pyrolysis Process. Ping Wu Chang and George T. Preston

1. Introduction. . ............... . 2. Process Description . . ....... .

2.1. Front End System .. 2.2. Pyrolysis System .

3. Material and Energy Balances. 4. Product Characterization ........... .

4.1. Pyrolytic Oil. . ....... . 4.2. Glass ....................... . 4.3. Ferrous Metal 4.4. Aluminum ................... .

5. Further Applications. 5.1. Solid Refuse Derived Fuel 5.2. Flash Pyrolysis of Industrial Wastes 5.3. Gasification .......... .

References .

10. Carboxylolysis of Biomass .. T. E. Lindemuth

1. Basic Process Description .. 1.1. Feedstock Applicability. 1.2. Potential Products

2. Background ........ . 2.1. Albany PDU Design and Construction. 2.2. PDU Operational Results. 2.3. Supporting Research.

3. Conceptual Process Description. 3.1. Reactor....................................... .. 3.2. Product Separation .. . 3.3. Gasification ............... . 3.4. Design Basis. . ............. . 3.5. Conceptual Plant and Equipment Description ..

3.5.1. Wood Preparation 3.5.2. Syngas Production ....... . 3.5.3. Reaction Process. 3.5.4. Product Separation .............. . 3.5.5. Plant Balance .

4. Process Efficiency ................... . 5. Conceptual Economics ....... . References .

11. The Tech-Air Pyrolysis Process Carl F. Pomeroy

1. Introduction. 2. Bench-Scale Reactor. 3. Prototype Plant 4. Pilot Plant

xi

173

173 174 174 176 178 180 180 183 183 183 184 184 184 184 185

187

187 187 187 188 188 188 189 191 191 192 193 193 193 194 195 195 197 197 198 198 200

201

201 201 203 203

xii

12.

5. Demonstration Plant .................. . 6. Process Description . 7. Product Yields ... 8. Product Characteristics. 9. Product Uses

10. Process Efficiency ..................... . References .

The Purox Process. .. . ...... . Anil K. Chatterjee

1. Introduction. . ............... . 2. Description of Process.

2.1. Preprocessing Plant. 2.2. The Basic Process .. 2.3. Purox Gasification Scheme .. 2.4. Gas Cleaning .. 2.5. Wastewater Treatment .. 2.6. Oxygen Plant .. 2.7. Gas Compression and Drying .. 2.8. Process Equipment

3. Performance. 4. Case History ....................................... . 5. Economics ........ .

5.1. Construction and Operating Costs ................ . 5.2. Product Cost Analysis ..

6. Applications of Purox Fuel Gas. References. Suggested Reading ..

13. Gasification .. Anil K. Chatterjee

1. Introduction. 2. Types of Gasifiers

2.1. Fixed Bed ... 2.2. Fluidized Bed .. 2.3. Entrained Bed .

3. Fuels for Gasifiers 4. Thermochemistry.. . .................. . 5. Design Considerations. 6. Performance Characteristics ...................... . 7. Combustion Characteristics. 8. Ancillary Equipment. 9. Utilization of Biomass Fuel References Suggested Reading .

14. The Syngas Recycle Process Herman F. Feldmann

I. The Concept. .

Contents

203 206 207 208 209 209 210

213

213 214 214 217 217 219 220 220 220 220 221 225 225 225 227 232 233 233

235

235 235 237 242 244 245 245 250 253 256 261 261 262 262

265

265

Contents xiii

2. Experimental Basis for the Process . 267 3. Reactor Design Considerations 267 4. Material Balance. . . . . . . . . . . . . . . . . 268 5. Integrated Process Flowsheet . . . . . . . . 270 6. Process Energy and Material Balances . . . . . . . . 272 References. . . . . . . . . . . . 274

Section C. Biochemical Conversion Processes

15. Basic Principles of Bioconversions in Anaerobic Digestion and Methanogenesis. . 277

Michael J. McInerney and Marvin P. Bryant

1. Introduction. 2. Stages of the Fermentation

2.1. Two-Stage Scheme . 2.2. Three-Stage Scheme. 2.3. Metabolic Groups Involved in Partial Methane Fermentation

3. The Methanogens 3.1. Physiology ..................... . 3.2. Phylogeny and Taxonomy ............... . 3.3. Substrates ......................................... .

4. The Fermentative Bacteria. 4.1. Fermentation of Polysaccharides. . ...... . 4.2. First Site of H2 Regulation. . ........... . 4.3. Fermentation of Other Complex Substrates

5. The H2-Producing Acetogenic Bacteria. 5.1. Ethanol and Lactate Fermentations. 5.2. Fatty Acid-Oxidizing, H2-Producing Bacteria 5.3. Second Site of H2 Regulation ............... .

6. Stoichiometry, Kinetics, Environmental and Nutrient Parameters of Fermentation. . .......................... . 6.1. Stoichiometry............. . .......... . 6.2. Kinetic Factors Influencing Efficiency ..

6.2.1. Effect of Retention Time (RT) . 6.2.2. Rate-Limiting Step 6.2.3. Effect of Volumetric Organic Loading Rate

6.3. Nutrient and Environmental Requirements 7. Summary. References

16. Design of Small-Scale Biogas Plants. Michael R. Brule'

1. Introduction .. 2. Biomass Conversion to Methane

2.1. The Biogasification Process 2.2. Large-Scale Commercial Endeavors 2.3. Potential for Small-Scale Facilities .

277 278 278 278 279 279 280 280 281 284 284 285 286 286 287 287 289

290 290 290 291 291 292 292 293 294

297

297 297 297 298 298

xiv

17.

18.

Contents

3. Small-Scale Biogas-Processing Facilities. . . . . . . . . . . . . . . . . 299 3.1. Biogas Plants for Dairies and Farms. . . . . . . . 299 3.2. Pollution-Control Advantages 299 3.3. Development of Small-Scale Biogas Plants. 301

4. Biogas Plant Design and Construction ................ 302 4.1. Process Flow Description . . . . . . .. 302 4.2. Methane Storage System . . . . . . . . . . . . . . . . .. 306 4.3. Fertilizer Production. ..................... 306

5. Economic Feasibility and Marketability. . . . . . . . 308 References . . . . . . . . 309

Anaerobic Digestion of Kelp. David P. Chynoweth, Sambhunath Ghosh, and Donald L. Klass

1. Introduction. . .................................. . 2. Characteristics of Kelp Feeds. 3. Biomethanogenesis of Kelp.

3.1. Performance Parameters. . . . ............. . 3.1.1. Gas Production. . . . ....... . 3.1.2. Conversion of Organic Matter ....... .

3.2. Maximum Theoretical Yields and Heat of Reaction. 3.3. Bench-Scale Digestion Studies. . . . ...... .

3.3.1. Organic Composition of Feeds ........ . 3.3.2. Potential Nutrient Limitation .. 3.3.3. Inoculum .. 3.3.4. Temperature .. 3.3.5. Inhibitory Substances in Feed .......... . 3.3.6. Hydraulic Retention Time (HRT) 3.3.7. Feed Concentration .......... . 3.3.8. Particle Size .. 3.3.9. Mixing. . ................ . 3.3.10. Feeding Frequency .......................... . 3.3.11. Catabolite Repression

3.4. Component and Energy Balance for Biomethanation of Raw Kelp ........ .

4. Summary. . ............... . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .....

Basic Principles of Ethanol Fermentation

Douglas M. Munnecke

1. Introduction .... 2. Why Microbes Produce Ethanol? 3. Substrates for Ethanol Production. 4. Substrate Preparation . . ......... . 5. Substrate Metabolism. 6. Effect of Microorganisms on Ethanol Production. 7. Effect of Fermentation Parameters 8. Fermentation Systems .. 9. Conclusions References ..

315

315 318 321 322 323 323 325 325 325 327 329 329 330 332 333 333 333 333 334

334 335 337

339

339 340 341 341 342 346 348 351 352 353

Contents

19. Ethanol Production by Fermentation.

D. Brandt

1. Introduction. 2. Feedstock Selection.

2.1. Pretreatment Design ................ . 2.2. Pretreatment Costs . . . . . . . . . . ................ . 2.3. Feedstock Price . . . . . . . . . . . . . . . . . . . . .. . ...... . 2.4. By-Product Credit. . ........ . 2.5. Waste Treatment.

3. Process Description ..................................... . 3.1. Feedstock Preparation.

3.1.1. Physical Reduction .. 3.1.2. Substrate Hydrolysis ............... . 3.1.3. Feedstock Sterilization .. 3.1.4. Concentration Adjustment

3.2. Ethanol Fermentation .. 3.2.1. Batch Fermentation . 3.2.2. Continuous Fermentation ........ . 3.2.3. Yeast Supply. . ......... .

3.3. Ethanol Recovery ...................... . 3.3.1. Stillage Separation .. . 3.3.2. Anhydrous Distillation. 3.3.3. Product Specifications.

3.4. By-Product Recovery 4. Conversion Efficiency

4.1. Independent Plant . 4.2. Integrated Plant.

5. Energy Efficiency .. 6. Conclusion .. References.

PART III.TECHNICAL AND ECONOMIC CONSIDERATIONS

xv

357

357 358 358 360 360 360 360 360 364 364 365 365 365 365 366 366 366 367 367 367 368 368 369 369 370 371 371 372

20. Technical Considerations of Biomass Conversion Processes. . 377

John M. Radovich

1. Material Balances ....... . 1.1. Basic Equations and Guidelines. . . . . . . . .. . ........ .

1.1.1. System Boundaries; Choosing a Basis; Composition Data ............. .

1.1.2. Chemical Reactions and Yields 1.1.3. Units ........ .

1.2. Applications to Conversion Processes ....... . 1.2.1. Air-Blown Gasifier. 1.2.2. Pyrolysis-Gasification Reactor. 1.2.3. Pyrolysis of Wood.

377 377

378 379 380 380 380 382 383

xvi Contents

21.

2. Energy Balances ........... . 2.1. Basic Equations and Guidelines. . ............. .

2.1.1. Calculation of Enthalpy Changes . . . ...... . 2.1.2. Simplified Forms of the Energy Balance Equation.

2.2. Applications to Conversion Processes 2.2.1. Pyrolysis of Wood ... 2.2.2. Pyrolysis-Gasification Reactor.. . ........ .

3. Evaluation of Process Efficiency. 3.1. Criteria. 3.2. Thermal or Energy Efficiency 3.3. Thermodynamic Efficiency .. 3.4. Recommendations

References . . . . . . . . . . . . . . . . .....

Economic Considerations of Biomass Conversion Processes

Fred A. Schooley

1. Introduction. . ....... . 1.1. Level of Estimating the Desired Precision. . ........ . 1.2. Assumed Study Purpose and Conditions. . ........ .

2. General Guidelines . . . ................. . 2.1. Analysis Uniformity ............... . 2.2. Life Cycle Costing. . ....................... . 2.3. Money Time Value. . ....... .

3. Capital Investment Economics. . . . .............. . 3.1. Plant General Facilities ................ . 3.2. Plant Utilities .. 3.3. Land Investment .................................. . 3.4. Working Capital .............................. . 3.5. Organization and Start-Up Costs. 3.6. Depreciable Investment. . . ....................... . 3.7. Plant On-Stream Factor. . . . ................. . 3.8. Conversion Plant Capacities. . ...... .

4. Feedstock Prices 5. Operating and Maintenance Costs ..... 6. Calculation of Revenue Requirements ..

6.1. Revenue Required-Non Regulated Industry .. 6.2. Revenue Required-Regulated Industry ............. .

References ........................ .

INDEX ............ .

38'4 387 387 389 390 390 391 392 393 393 396 397 397

399

399 399 400 400 401 401 402 403 403 404 404 404 404 405 405 405 405 406 407 408 408 409

411