Advanced Gas Turbine Cycles
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Advanced Gas Turbine Cycles Corn bined STlG Steam - Exhaust 4 Water 1i li qL t Air PERGAMON ADVANCED GAS TURBINE CYCLES ADVANCED GAS TURBINE CYCLES J. H. Horlock F.R.Eng., F.R.S. Whittle Laboratory Cambridge, U.K. 2003 An imprint of Elsevier Science AMSTERDAM * BOSTON . HEIDELBERG . LONDON . NEW YORK OXFORD . PARIS * SAN DEGO * SAN FRANCISCO SINGAPORE SYDNEY . TOKYO ELSEVIER SCIENCE Ltd The Boulevard, Langford Lane Kidlington, Oxford OX5 lGB, UK 0 2003 Elsevier Science Ltd. All rights reserved. This work is protected under copyright by Elsevier Science, and the following terms and conditions apply to its use: Photocopying Single photocopies of single chapters may be made for personal use as allowed by national copyright laws. Permission of the Publisher and payment of a fee is required for all other photocopying, including multiple or systematic copying, copying for advertising or promotional purposes, resale, and all forms of document delivery. 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Notice No responsibility is assumed by the Publisher for any injury andor damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions or ideas contained in the material herein. Because of rapid advances in the medical sciences, in particular, independent verification of diagnoses and drug dosages should be made. First edition 2003 Library of Congress Cataloging in Publication Data A catalog record from the Library of Congress has been applied for. British Library Cataloguing in Publication Data A catalogue record from the British Library has been applied for. ISBN 0-08-044273-0 @ The paper used in this publication meets the requirements of ANSI/NISO 239.48-1992 (Permanence of Paper). Printed in The Netherlands To W.R.H. Preface ................................................. xiii Notation ................................................ xvii Chapter 1. A brief review of power generation thermodynamics..... 1 1.1. Introduction .................................. 1.2. Criteria for the performance of power plants ............ 1.2.1. Efficiency of a closed circuit gas turbine plant ........... 1.2.2. Efficiency of an open circuit gas turbine plant ........... 1.2.3. Heatrate .................................... 1.2.4. Energy utilisation factor .......................... 1.3. Ideal (Carnot) power plant performance ............... 1.4. Limitations of other cycles ........................ 1.5. Modifications of gas turbine cycles to achieve higher thermalefficiency .............................. 9 References ................................... 11 Chapter 2. Reversibility and availability...................... 13 2.1. Introduction .................................. 13 2.2. Reversibility. availability and exergy ................. 14 2.2.1. Flow in the presence of an environment at To (not involving chemical reaction) ....................... 14 2.2.2. Flow with heat transfer at temperature T ............... 16 2.3. Exergy flux ................................... 19 2.3.1. Application of the exergy flux equation to a closed cycle .... 20 2.3.2. The relationships between 6. (+and ZCR. ZQ ............. 20 2.4. The maximum work output in a chemical reaction at To..... 22 2.5. The adiabatic combustion process.................... 23 2.6. The work output and rational efficiency of an open circuit gas turbine ................................... 24 2.7. A final comment on the use of exergy ................. 26 References ................................... 26 Chapter 3 Basic gas turbine cycles ......................... 27 3.1. Introduction .................................. 27 vii viii Confenrs 3.2. Air standard cycles (uncooled) ...................... 28 3.2.1. Reversible cycles ............................... 28 3.2.1.1. The reversible simple (Joule-Brayton) cycle. [CHTIR....... 28 3.2.1.2. The reversible recuperative cycle [Cm]R.............. 29 3.2.1.3. The reversible reheat cycle [CHTHTIR ................. 30 3.2.1.4. The reversible intercooled cycle [CICHTIR .............. 32 3.2.1.5. The 'ultimate' gas turbine cycle ..................... 32 3.2.2. Irreversible air standard cycles ...................... 33 3.2.2.1. Component performance .......................... 33 3.2.2.2. The irreversible simple cycle [CHTII .................. 34 3.2.2.3. The irreversible recuperative cycle [CHTXII ............. 37 3.2.3. Discussion .................................... 39 3.3. The [CBTII open circuit plant-a general approach ........ 39 3.4. Computer calculations for open circuit gas turbines ........ 43 3.4.1. The [CBTIIGplant ............................... 43 3.4.2. Comparison of several types of gas turbine plants .......... 44 3.5. Discussion .................................... 45 References .................................... 46 Chapter 4. Cycle efficiency with turbine cooling (cooling flow ratesspecified)................................. 47 4.1. Introduction ................................... 47 4.2. Air-standard cooled cycles ......................... 48 4.2.1. Cooling of internally reversible cycles ................. 49 4.2,l.l. Cycle [CHTIRCIwith single step cooling ............... 49 4.2.1.2. Cycle [cHT]RC* with two step cooling ................. 51 4.2.1.3. Cycle [cHT]Rm with multi-step cooling ............... 52 4.2.1.4. The turbine exit condition (for reversible cooled cycles) ..... 54 4.2.2. Cooling of irreversible cycles ....................... 55 4.2.2.1. Cycle with single-step cooling [CH'I'IIcl ................ 55 4.2.2.2. Efficiency as a function of combustion temperature or rotor inlet temperature (for single-step cooling) ........... 56 4.2.2.3. Cycle with two step cooling [CHTIIa ................. 58 4.2.2.4. Cycle with multi-step cooling [CHTlICM................ 59 4.2.2.5. Comment ..................................... 59 4.3. Open cooling of turbine blade rows-detailed fluid mechanics and thermodynamics...................... 59 4.3.1. Introduction ................................... 59 4.3.2. The simple approach ............................. 61 4.3.2.1. Change in stagnation enthalpy (or temperature) through an open cooled blade row .......................... 61 4.3.2.2. Change of total pressure through an open cooled blade row ... 62 4.3.3. Breakdown of losses in the cooling process .............. 64 Contents ix 4.4. Cycle calculations with turbine cooling ................ 65 4.5. Conclusions .................................. 68 References ................................... 69 Chapter 5. Full calculations of plant efficiency ................. 71 5.1. Introduction .................................. 71 5.2. Cooling flow requirements ........................ 71 5.2.1. Convective cooling ............................. 71 5.2.2. Film cooling .................................. 72 5.2.3. Assumptions for cycle calculations ................... 73 5.3. Estimates of cooling flow fraction ................... 73 5.4. Single step cooling ............................. 75 5.5. Multi-stage cooling ............................. 75 5.6. A note on real gas effects ......................... 82 5.7. Other studies of gas turbine plants with turbine cooling ..... 82 5.8. Exergy calculations ............................. 82 5.9. Conclusions .................................. 84 References ................................... 84 Chapter 6. ‘Wet’ gas turbine plants ......................... 85 6.1. Introduction .................................. 85 6.2. Simple analyses of STIG type plants .................. 85 6.2.1. The basic STIG plant ............................ 85 6.2.2. The recuperative STIG plant ....................... 90 6.3. Simple analyses of EGT type plants .................. 91 6.3.1. A discussion of dry recuperative plants with ideal heat exchangers