ANSI ASME PTC 12.3-1997 Performance Test Code on Deaerators.pdf

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1、 Intentionally left blank ASME PTC 12.3-1 997 (REVISION OF ASME PTC 12.3-1977) Performance Test Code on Deaerators Date of Issuance: October 31. 1997 This document will be revised when the Society approves the issuance of the next edition. There will be no Addenda issued to ASME PTC 12.3-1997. Pleas

2、e Note: ASME issues written replies to inquiries concerning interpretation of technical aspects of this document. The interpretations are not part of the document. PTC 12.3-1 997 is being issued with an automatic subscription service to the interpre- tations that will be issued to it up to the publi

3、cation of the next edition. ASME is the registered trademark of The American Society of Mechanical Engineers. This code or standard was developed under procedures accredited as meeting the criteria for American National Standards. The Consensus Committee that approved the code or standard was balanc

4、ed to assure that individuals from competent and concerned interests have had an opportunity to participate. The proposed code or standard was made available for public review and comment which provides an opportunity for additional public input from industry, academia, regulatory agencies, and the

5、public- at-large. ASME does not “approve,“ “rate,“ or “endorse“ any item, construction, proprietary device, or activity. ASME does not take any position with respect to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to insur

6、e anyone utilizing a standard against liability for infringement of any applicable Letters Patent, nor assume any such liability. Users of a code or standard are expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely t

7、heir own responsibility. Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpre- ted as government or industry endorsement of this code or standard. ASME accepts responsibility for only those interpretations issued in accordance with governing A

8、SME procedures and policies which preclude the issuance of interpretations by individual volunteers. No part of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. The American Society of Mechanical Engin

9、eers 345 East 47th Street New York. NY 1001 7 Copyright 0 1997 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A. FOREWORD (This Foreword is not part of ASME PTC 12.3-1997.) On September 1, 1989, the Board on Performance Test Codes (BPTC) voted to reactivate the Pe

10、rformance Test Code committee, PTC 12.3, to undertake the revision of PTC 12.3- 1977, the Performance Test Code on Deaerators. Shortly thereafter, the Committee was reconstituted, and had its first meeting on May 22-23, 1991, with 3 of the original members on the new Committee. One of the requiremen

11、ts for the satisfactory operation of the boiler feed system in a steam plant is high quality boiler feedwater, freefrom dissolved oxygen and carbon dioxide. To meet the dissolved oxygen requirements of the steam generator, improvements in the design of mechanical deaerators have been made. Design re

12、quirements demand extreme reliability of oxygen testing of boiler feedwater. This Code was approved by the PTC 12.3 committee on May 31, 1996. It was then approved and adopted by the Council as a Standard practice of the Society by action of the BPTC on October 25, 1996. This Performance Test Code w

13、as also approved as an American National Standard by the ANSI Board of Standards Review on February 6,1997. . Ill NOTICE All Performance Test Codes MUST adhere to the requirements of PTC 1, GENERAL INSTRUCTIONS. The following information is based on that document and is included here for emphasis an

14、d for the convenience of the user of this Code. It is expected that the Code user is fully cognizant of Parts I and I11 of PTC 1 and has read them prior to applying this Code. ASME Performance Test Codes provide test procedures which yield results of the highest level of accuracy consistent with the

15、 best engineering knowledge and practice currently available. They were developed by balanced committees representing all con- cerned interests. They specify procedures, instrumentation, equipment operating require- ments, calculation methods, and uncertainty analysis. When tests are run ih accordan

16、ce with this Code, the test results themselves, without adjustment for uncertainty, yield the best available indication of the actual performance of the tested equipment. ASME Performance Test Codes do not specify means to compare those results to contractual guarantees. Therefore, it is recommended

17、 that the parties to a commercial test agree before starting the test and preferably before signing the contract on the method to be used for comparing the test results to the contractual guarantees. It is beyond the scope of any code to determine or interpret how such compari- sons shall be made. i

18、v PERSONNEL OF PERFORMANCE TEST CODE COMMITTEE NO. 12.3 ON DEAERATORS (The following is the roster of the Committee at the time of approval of this Code.) OFFICERS john j. Eibl, Chair Thomas j. McAlee, Vice Chair lack H. Karian, Secretary COMMITTEE PERSONNEL Joseph H. Duff, Water Technology Services

19、, Inc. Michael Dymarski, Ontario Hydro john 1. Eibl, E. 1. Dupont Carol S. Coolsby, Duke Power Company A. Scott Hamele, Kansas City Deaerator Company David Hickling, Ecodyne Limited jack H. Karian, American Society of Mechanical Engineers Thomas 1. McAlee, The United Illuminating Company Scott D. Ro

20、ss, Sterling Deaerator Company Dave A. Velegol, Weirton Steel Corporation Joseph H. Wilkinson, Royce Instrument The PTC 12.3 Committee wishes to acknowledge the contributions of Robert J. Beckwith and the late James S. Poole. It is with regret that Mr. Poole did not live to see the result of his eff

21、orts for which the Committee is most grateful. V R. P. Allen R. L. Bannister B. Bornstein J. M. Burns J. R. Friedman G. J. Gerber P. M. Gerhart R. S. Hecklinger BOARD ON PERFORMANCE TEST CODES OFFICERS D. R. Keyser, Chair P. M. Cerhart, Vice Chair W. 0. Hays, Secretary COMMITTEE PERSONNEL R. W. Henr

22、y D. R. Keyser S. J. Korellis J. W. Milton G. H. Mittendorf, Jr. S. P. Nuspl R. P. Perkins A. L. Plumley S. B. Scharp 1. Siegmund J. A. Silvaggio, Jr. R. E. Sornrnerlad W. G. Steele, Jr. 1. C. Westcott I. G. Yost vi CONTENTS Foreword CommitteeRoster BoardRoster Section . 0 1 2 3 4 5 6 7 introduction

23、 . Object and Scope . Guiding Principles . Instruments and Methods of Measurement . Computation of Results . ReportofTest Definitions and Rescription of Terms . Detailed Uncertainty Analysis for Dissolved Oxygen . Figures 1 Method and Apparatus for the Detection of Free Air . 2 500 mL Sample Flask f

24、or Dissolved Oxygen Determination 4 General Arrangement for Sampling Apparatus 5 Procedure for Preparation of Samples for Titration 3 MicroBuret . Tables 4.1 5.1 6.1 6.2 6.3 D.l D.2 D.3 D.4 D.5 D.6 Reagents Required for Dissolved Oxygen Test Method General Information and Description of Equipment Il

25、lustration of Dissolved Oxygen Test Results . dias Limits and Precision indices Example of Outliers Determination Two-Tailed Students t Table for the 95% Confidence Level Modified Thompson T (at the 5% Significance Level) . Approximate Effect of Various Interfering Compounds on Standard BiasLimit .

26、Test Operating Conditions . Analytical Data . Breakdown of Measurement Component Errors into Elemental Errors . Appendices A Starch Titration . . Ill V vi 1 3 5 7 71 23 29 33 10 12 13 18 21 15 26 29 30 31 44 45 46 46 47 47 35 vii B C D E F On-Line Analyzer Method . 39 Colorimetric Method . 41 Exampl

27、e Calculations 43 Typical Deaerator Sample Point Locations . 49 References 51 viii ASME PTC 12.3-1997 SECTION 0- 0.1 Deaerating equipment is designed to remove the dissolved oxygen and carbon dioxide in boiler feed- water to reduce corrosion in boilers and associated equipment. Normally, dissolved o

28、xygen levels of 7 pg/L (ppb) or less can be achieved. A deaerator is designed to heat feedwater to the temperature of saturated steam at the pressure within the deaerator. 0.2 Deaerators, or deaerating heaters, may utilize many different designs. In general, there is a first stage which involves spr

29、aying water into the steam space where it is heated and partially deaerated. Water is discharged from spray nozzles or other spray devices as thin films, sheets or droplets. This stage removes more than 90% of the dissolved oxygen. Venting of gases removed from the water may occur through an externa

30、l shell and tube condenser or through an internal direct-contact vent condenser in the upper steam space on the deaerator. The condensing of steam in the apparatus reduces its pressure progressively, as it travels upward, to a minimum pressure in the area of the vent condenser. Noncondensable gases

31、plus a small amount of steam pass through the vent. The falling water, containing some dissolved gases, may be directed to a second stage which may be a tray section where it is mixed with, and mechanically scrubbed by, the heating steam. Thin films of water, formed by water overflowing the lips of

32、the trays, are deaerated further by the incoming steam. Alternatively, the second stage may be a steam scrubber and/or reboiler. Here the water mixes with the incoming heating steam, with the water becom- ing slightly superheated during the heating and scrub- bing process. Some flashing takes place

33、as it is discharged into the steam space where final deaera- tion takes place. There are other types of deaerators which use sprays or spray pipes of various types with various types of packing such as packing rings, saddles, INTRODUCTION etc., on their own or in combination. There are also “integra

34、l“ and other types of deaerators. Deaerators may be designed to operate at any pressure. 0.3 Accurate measurements of dissolved oxygen are not obtained easily. Some test methods and proce- dures, while satisfactory for chemical control of the feedwater, are inadequate for guarantee-acceptance purpos

35、es. The fact that there are many test methods available and wide choices of apparatus and proce- dures which may be employed further complicates this problem. With the magnitude of permissible error of the test defined, it becomes apparent that the test method, test apparatus, and test procedure mus

36、t be integrated and evaluated so that reliable measurement can be achieved. On-line analyzers and colorimetric test methods do not meet the methodology of measurement uncertainty per PTC 19.1. The test methods and procedures described herein do meet the methodology of PTC 19.1 The Test described in

37、Subsection 4.2 is the referee method because it provides a method which has been studied and tested for accuracy and reliability. 0.4 Before formulating a test to determine the perform- ance of deaerators, the Performance Test Code on General Instructions (PTC-1) should be studied and followed in de

38、tail. In particular, before any test is undertaken, the test objectives shall be defined and agreed by the parties to the test. The Code on Definitions and Values (PTC-2) de- fines technical terms and numerical constants which are used throughout this Code with the meanings and values therein establ

39、ished. The PTC 19 Series Supplements (Instruments and Apparatus Supplements) gives descriptions of, and standard directions for, the use and calibration of measuring devices, including an estimate of the level 1 ASME PTC 12.3-1997 of accuracy obtainable. These supplements provide guidance on the app

40、lication of some of the special- ized techniques used in this code. DEAERATORS 2 DEAERATORS ASME PTC 12.3-1997 SECTION 1 - OBJECT AND SCOPE 1.1 Object The purpose of this Code is to provide rules and test procedures that are to be used to determine the performance of deaerators with regard to the fo

41、llowing: (a) residual dissolved oxygen in the deaerated water, (b) terminal temperature difference (TTD), if any, between the deaerated water and the saturated steam temperature corresponding to the pressure in the steam zone adjacent to the interface between the steam and the collected deaerated wa

42、ter. 1.2 Scope 1.2.1 This Code applies to deaerating heaters and deaerators equipped with either shell-and-tube or direct contact, vent-condensing sections. 1.2.2 The Code describes the test method and procedures for the determination of dissolved oxygen in water for deaerating equipment at concentr

43、ations up to 75 pg/L (ppb). This Code also describes the method for determining the terminal temperature difference (TTD). Other methods of dissolved oxygen measurement are included in Appendices A, B and C. These may be used as an adjunct to the Code. 1.3 Uncertainty An uncertainty analysis of the

44、test method for determination of dissolved oxygen in the deaerated water and terminal temperature difference is pro- vided. This uncertainty procedure serves as a guide for pretest and post-test uncertainty calculations when the Code is used. The expected test uncertainty for dissolved oxygen is 22.

45、6 pg/L (ppb) and for terminal temperature difference is 20.6“C (2 1 OF). These values were determined in accordance with methods described in PTC 19.1. 3 Intentionally left blank DEAERATORS ASME PTC 12.3-1997 SECTION 2 - DEFINITIONS AND DESCRIPTION OF TERMS 2.1 SYMBOLS Term Symbol Unit Remarks Heati

46、ng Load Steam flow to deaerator, actual Steam flow to deaerator, ideal Steam pressure at deaerator inlet Steam temperature at deaerator Steam quality at deaerator inlet Steam enthalpy at deaerator inlet Steam pressure in deaerator Saturated steam temperature in Enthalpy of liquid at saturation Water

47、 flow to deaerator Water pressure at inlet to Water temperature at inlet to Water enthalpy at inlet to Water temperature at outlet of Water enthalpy at outlet of Water enthalpy increase Terminal temperature difference Flow rates of various drains entering deaerating and/or storage section inlet deae

48、rator conditions in deaerator deaerator deaerator deaerator deaerator deaerator Enthalpy of various drains entering deaerator and/or storage section Net outlet flow rate Gross outlet flow rate Dissolved Oxygen Rate of heat transferred to feedwater Actual steam supplied for heating, deaerating and ve

49、nting, including losses assuming zero terminal temperature difference Calculated steam flow required, By calorimeter From steam tables at p, and ts or x, From steam tables, From steam tables at ph or th corresponding to Ph From steam tables at ti and pw From steam tables at tz and Ph By subtraction, h2 - hi Equals th - t2 Measured or computed from plant heat balance Measured or computed from plant heat balance Water leaving deaerator storage section exclusive of boiler feed pump recirculation Water leaving deaerato