IEC_TR_62140-1-2002.pdf

TECHNICALREPORTIECTR 62140-1First edition2002-10Fossil-fired steam power stations Part 1:Limiting controlsCentrales vapeur consommant des combustibles fossiles Partie 1:Rgulations de limitationReference numberIEC/TR 62140-1:2002(E)LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.Publication numberingAs from 1 January 1997 all IEC publications are issued with a designation in the60000 series.For example,IEC 34-1 is now referred to as IEC 60034-1.Consolidated editionsThe IEC is now publishing consolidated versions of its publications.For example,edition numbers 1.0,1.1 and 1.2 refer,respectively,to the base publication,thebase publication incorporating amendment 1 and the base publication incorporatingamendments 1 and 2.Further information on IEC publicationsThe technical content of IEC publications is kept under constant review by the IEC,thus ensuring that the content reflects current technology.Information relating tothis publication,including its validity,is available in the IEC Catalogue ofpublications(see below)in addition to new editions,amendments and corrigenda.Information on the subjects under consideration and work in progress undertakenby the technical committee which has prepared this publication,as well as the listof publications issued,is also available from the following:IEC Web Site(www.iec.ch)Catalogue of IEC publicationsThe on-line catalogue on the IEC web site(http:/www.iec.ch/searchpub/cur_fut.htm)enables you to search by a variety of criteria including text searches,technicalcommittees and date of publication.On-line information is also available onrecently issued publications,withdrawn and replaced publications,as well ascorrigenda.IEC Just Published This summary of recently issued publications(http:/www.iec.ch/online_news/justpub/jp_entry.htm)is also available by email.Please contact the CustomerService Centre(see below)for further information.Customer Service CentreIf you have any questions regarding this publication or need further assistance,please contact the Customer Service Centre:Email:custserviec.chTel:+41 22 919 02 11Fax:+41 22 919 03 00LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.TECHNICALREPORTIECTR 62140-1First edition2002-10Fossil-fired steam power stations Part 1:Limiting controlsCentrales vapeur consommant des combustibles fossiles Partie 1:Rgulations de limitationPRICE CODE IEC 2002 Copyright-all rights reservedNo part of this publication may be reproduced or utilized in any form or by any means,electronic ormechanical,including photocopying and microfilm,without permission in writing from the publisher.International Electrotechnical Commission,3,rue de Varemb,PO Box 131,CH-1211 Geneva 20,SwitzerlandTelephone:+41 22 919 02 11 Telefax:+41 22 919 03 00 E-mail:inmailiec.ch Web:www.iec.chXAFor price,see current catalogueCommission Electrotechnique InternationaleInternational Electrotechnical Commission LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.2 TR 62140-1 IEC:2002(E)CONTENTSFOREWORD.5INTRODUCTION.71Scope.82Terms,subscripts and abbreviations.82.1Notations.82.2Subscripts.92.3Abbreviations(also used as subscripts).93Function of limiting controls.103.1Values to be limited.113.2Functional modules for limiting.114List of limiting controls.11Annex A Upper limiting of steam pressure of steam generators.16A.1Task.16A.2Description of the control structure.17A.3Operating behaviour.18A.4Supplementary information.19Annex B Lower limiting of steam pressure of steam generators.20B.1 Task.20B.2 Description of the control structure.21B.3 Operating behaviour.22B.4 Supplementary information.22Annex C Limiting control of thermal stresses in pressure-bearing components.23C.1Task.23C.2Description of the control structure.23C.3Operating behaviour.26Annex D Lower limiting of evaporator flow for once-through boilers.27D.1Task.27D.2Description of the control structure.27D.3Operating behaviour.32Annex E Limiting controls on the feed-water function group.36E.1Task.36E.2Description of the control structure.39E.3Operating behaviour.40E.4Further control structures.44LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.TR 62140-1 IEC:2002(E)3 Annex F Lower limiting of furnace thermal output,using as an example direct-firingpulverized coal furnace.46F.1Task.46F.2Description of the control structure.49F.3Operating behaviour.49Annex G Permissible turbine thermal stresses.51G.1Task.51G.2Description of the control systems.51G.3Operating behaviour.53G.4 Supplementary information.53Index.54Figure 1 Change in a controlled variable over time.10Figure A.1 Plant circuit diagram for upper steam pressure limiting control usingbypass devices.16Figure A.2 Pressure characteristics of a conventional power station unit,shown formodified sliding pressure.17Figure A