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Mechanical Engineering Steam Generators and Waste Heat Boilers For Process and Plant Engineers "This book is an ideal reference for anyone involved in the heat transfer field. It is practical for use as a reference by plant personnel who need an answer ‘right now’ but it is detailed enough to allow consulting S engineers, process engineers, manufacturing engineers, designers, and even students to get a compre- t hensive understanding of how the equipment works and how to make sure what they have designed is e really in the best interest of the plant." a —Bob Stemen, Applied Heat Recovery, USA m Incorporates Worked-Out Real-World Problems G Steam Generators and Waste Heat Boilers: For Process and Plant Engineers focuses on the e thermal design and performance aspects of steam generators, HRSGs and fire tubes, water tube n waste heat boilers including air heaters, and condensing economizers. Over 120 real-life problems e Steam Generators are fully worked out, which will help plant engineers evaluate new boilers or make modifications to r existing boiler components without assistance from boiler suppliers. The book examines recent a trends and developments in boiler design and technology and presents novel ideas for improving t boiler efficiency and lowering gas pressure drop. It helps plant engineers understand and evaluate o the performance of steam generators and waste heat boilers at any load. r s Waste Heat Boilers Learn How to Independently Evaluate the Thermal Performance of Boilers and Their Components a and n This book begins with basic combustion and boiler efficiency calculations. It then moves on to d estimation of furnace exit gas temperature (FEGT), furnace duty, view factors, heat flux, and boiler circulation calculations. It also describes trends in large steam generator designs such as multi- W For Process and Plant Engineers ple-module; elevated drum design types of boilers such as D, O, and A; and forced circulation steam generators. It illustrates various options to improve boiler efficiency and lower operating costs. The a author addresses the importance of flue gas analysis, fire tube versus water tube boilers used in s chemical plants, and refineries. In addition, he describes cogeneration systems; heat recovery in t sulfur plants, hydrogen plants, and cement plants; and the effect of fouling factor on performance. e The book also explains HRSG simulation process and illustrates calculations for complete performance evaluation of boilers and their components. H e • Helps plant engineers make independent evaluations of thermal performance of a boilers before purchasing them t • Provides numerous examples on boiler thermal performance calculations that help B plant engineers develop programming codes with ease • Follows the metric and SI system, and British units are shown in parentheses o wherever possible i l • Includes calculation procedures for the basic sizing and performance evaluation of e a complete steam generator or waste heat boiler system and their components with r appendices outlining simplified procedures for estimation of heat transfer coefficients s Steam Generators and Waste Heat Boilers: For Process and Plant Engineers serves as a source book for plant engineers, consultants, and boiler designers. K23620 Steam Generators Waste Heat Boilers and For Process and Plant Engineers MECHANICAL ENGINEERING A Series of Textbooks and Reference Books Founding Editor L. L. Faulkner Columbus Division, Battelle Memorial Institute and Department of Mechanical Engineering The Ohio State University Columbus, Ohio RECENTLY PUBLISHED TITLES Steam Generators and Waste Heat Boilers: For Process and Plant Engineers V. Ganapathy Maintenance, Replacement, and Reliability: Theory and Applications, Second Edition Andrew K.S. Jardine and Albert H.C. Tsang Heat Exchanger Design Handbook, Second Edition, Kuppan Thulukkanam Vehicle Dynamics, Stability, and Control, Second Edition, Dean Karnopp HVAC Water Chillers and Cooling Towers: Fundamentals, Application, and Operation, Second Edition, Herbert W. Stanford III Ultrasonics: Fundamentals, Technologies, and Applications, Third Edition, Dale Ensminger and Leonard J. Bond Mechanical Tolerance Stackup and Analysis, Second Edition, Bryan R. Fischer Asset Management Excellence, John D. Campbell, Andrew K. S. Jardine, and Joel McGlynn Solid Fuels Combustion and Gasification: Modeling, Simulation, and Equipment Operations, Second Edition, Third Edition, Marcio L. de Souza-Santos Mechanical Vibration Analysis, Uncertainties, and Control, Third Edition, Haym Benaroya and Mark L. Nagurka Principles of Biomechanics, Ronald L. Huston Practical Stress Analysis in Engineering Design, Third Edition, Ronald L. Huston and Harold Josephs Practical Guide to the Packaging of Electronics, Second Edition: Thermal and Mechanical Design and Analysis, Ali Jamnia Steam Generators Waste Heat Boilers and For Process and Plant Engineers Boca Raton London New York CRC Press is an imprint of the Taylor & Francis Group, an informa business CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2015 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20140331 International Standard Book Number-13: 978-1-4822-4714-5 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the valid- ity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or uti- lized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopy- ing, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http:// www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Dedicated to plant and process engineers who henceforth will be able to evaluate boiler and HRSG performance without assistance from boiler suppliers! Contents Preface ...........................................................................................................................................xiii Author .........................................................................................................................................xxxi 1. Combustion Calculations .....................................................................................................1 Introduction ..............................................................................................................................1 Moisture in Air .........................................................................................................................1 Combustion Calculations .......................................................................................................2 Excess Air from Flue Gas Analysis ..................................................................................8 Simplified Combustion Calculations .............................................................................10 Estimation of Heating Values ...............................................................................................12 Burner Selection .....................................................................................................................13 Combustion Temperatures ...................................................................................................14 Simplified Procedure for Estimating Combustion Temperatures ..................................15 Effect of FGR on Combustion Temperature ..................................................................15 Relating FGR and Oxygen in Windbox .........................................................................16 Gas Turbine Exhaust Combustion Calculations ...............................................................17 Relating Oxygen and Energy Input in Turbine Exhaust Gases .................................17 Evaluating Fuel Quantity Required to Raise Turbine Exhaust Gas Temperature ......19 Firing Temperature versus Oxygen, Burner Duty, and Water Vapor ........................21 Boiler Efficiency .....................................................................................................................21 Heat Loss Method .............................................................................................................22 Simplified Formulae for Boiler Efficiency .....................................................................23 Simplified Procedure for Obtaining Major Boiler Parameters ...................................26 Excess Air versus Efficiency ............................................................................................26 Firing Fuels with Low Heating Values ...............................................................................27 Firing of Multiple Fuels .........................................................................................................29 Emission Conversion Calculations: Steam Generators ....................................................29 Converting ppmvd of NO to mg/Nm3 ..............................................................................32 x Converting Turbine Exhaust Emissions .............................................................................34 Low-Temperature Corrosion in Boilers ..............................................................................35 Condensation of Acid Vapors in Low-Temperature Heat Sinks .....................................38 Acid Dew Point Temperature T ....................................................................................38 dp References ...............................................................................................................................40 2. Steam Generator Furnace Design ......................................................................................41 Advantages of Water-Cooled Furnaces ..............................................................................43 Ring Header Design .........................................................................................................44 Heat Release Rates .................................................................................................................46 Steam Pressure ..................................................................................................................47 Circulation Systems ..........................................................................................................52 Furnace Exit Gas Temperature Evaluation .........................................................................53 Empirical Formula for Furnace Duty Estimation .............................................................57 vii viii Contents Furnace Duty with Combination Firing .............................................................................60 Distribution of Heat Flux around Tubes and Fins ............................................................61 Distribution of Radiation to Tube Banks ............................................................................61 Relating Heat Flux from Furnace to inside Tubes .............................................................64 External Radiation to Heat Transfer Surfaces at Furnace Exit ........................................65 Direct Radiation to Superheater at Part Load ...............................................................66 Terms Frequently Used in Furnace Performance..............................................................67 Estimating Boiling Heat Transfer Coefficient ....................................................................67 Estimating Fin Tip Temperature ..........................................................................................68 Boiling Process .......................................................................................................................69 Boiler Circulation ...................................................................................................................70 Thom’s Method for Estimating Losses ...............................................................................75 Circulation Calculations .......................................................................................................77 Circulation Flow versus Load .........................................................................................81 Flow Stratification in Horizontal Tubes ..............................................................................82 Correlations for CHF (Critical Heat Flux) and Allowable Steam Quality .....................82 Circulation Problems .............................................................................................................85 Guidelines for Good Circulation System Design ..............................................................85 References ...............................................................................................................................86 3. Steam Generators ..................................................................................................................87 Introduction ............................................................................................................................87 Large Package Boilers ............................................................................................................87 Water-Cooled Furnaces .........................................................................................................90 Major Changes in Boiler Design ..........................................................................................90 Absence of Air Heater ...........................................................................................................90 Emissions Affect Steam Generator Designs ......................................................................92 Custom-Designed Boilers .....................................................................................................97 Novel Ideas .............................................................................................................................97 O-Type Package Boiler ......................................................................................................98 Dual-Pressure Design .......................................................................................................99 Small Changes, Big Benefits ............................................................................................99 Boiler Classification .............................................................................................................103 Improving Boiler Efficiency ...............................................................................................108 Adding Condensate Heater to Improve Boiler Plant Efficiency ...............................109 Understanding Boiler Performance ..............................................................................111 Why Economizer Does Not Steam in Steam Generators ..........................................112 Understanding Boiler Surface Areas ............................................................................113 Steam Generators for Oil Sands Application ...................................................................115 Superheaters .........................................................................................................................118 Radiant versus Convective Superheaters ....................................................................121 How Emissions Impact Radiant and Convective Superheaters ...............................124 Arrangement of Superheaters .......................................................................................124 Steam Temperature Control ..........................................................................................125 Steam Generators with Import and Export Steam ..........................................................129 Flow in Parallel Paths ..........................................................................................................129 Steam Inlet and Exit Nozzle Location ...............................................................................130 Off-Design Performance of Superheater ...........................................................................131