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1、API 521-2007 Pressure-relieving and Depressuring Systems(英文版) Pressure-relieving and Depressuring Systems ANSI/API STANDARD 521 FIFTH EDITION, JANUARY 2007 ISO 23251 Identical , Petroleum and natural gas industriesPressure-relieving and depressuring systems Special Notes API publications necessarily
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9、cording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005. Copyright ? 2006 American Petroleum Institute API Standard 521 / ISO 23251 API Foreword Nothing contained in any API publication is
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15、org. ii Contents Page API Foreword . ii Foreword . v Introduction . vi 1 Scope . 1 2 Normative references . 1 3 Terms and definitions . 1 4 Causes of overpressure . 10 4.1 General . 10 4.2 Overpressure protection philosophy . 10 4.3 Potentials for overpressure . 11 4.4 Recommended minimum relief sys
16、tem design content . 17 4.5 List of items required in flare-header calculation documentation . 20 4.6 Guidance on vacuum relief. 20 5 Determination of individual relieving rates. 22 5.1 Principal sources of overpressure . 22 5.2 Sources of overpressure . 24 5.3 Effects of pressure, temperature, and
17、composition . 24 5.4 Effect of operator response . 24 5.5 Closed outlets . 24 5.6 Cooling or reflux failure . 25 5.7 Absorbent flow failure . 26 5.8 Accumulation of non-condensables . 26 5.9 Entrance of volatile material into the system . 26 5.10 Failure of process stream automatic controls . 27 5.1
18、1 Abnormal process heat input . 29 5.12 Internal explosion excluding detonation . 30 5.13 Chemical reaction . 30 5.14 Hydraulic expansion . 31 5.15 External pool fires . 36 5.16 Jet fires . 51 5.17 Opening manual valves . 51 5.18 Electric power failure . 51 5.19 Heat-transfer equipment failure . 52
19、5.20 Vapour depressuring . 55 5.21 Special considerations for individual pressure-relief devices . 63 5.22 Dynamic simulation . 64 6 Selection of disposal systems . 65 6.1 General . 65 6.2 Fluid properties that influence design . 65 6.3 Atmospheric discharge . 66 6.4 Disposal by flaring . 76 6.5 Dis
20、posal to a lower-pressure system .95 6.6 Disposal of liquids and condensable vapours . 96 7 Disposal systems . 97 7.1 Definition of system design load . 97 7.2 System arrangement . 100 7.3 Design of disposal system components . 102 7.4 Flare gas recovery systems . 137 ISO 23251:2006 E Annex A inform
21、ative Determination of fire relief requirements. 142 Annex B informative Special system design considerations . 146 Annex C informative Sample calculations for sizing a subsonic flare stack. 149 Annex D informative Typical details and sketches. 166 Annex E informative High integrity protection syste
22、ms HIPS . 169 Bibliography . 176 iv API Standard 521 / ISO 23251 ISO 23251:2006 E Foreword ISO the International Organization for Standardization is a worldwide federation of national standards bodies ISO member bodies . The work of preparing International Standards is normally carried out through I
23、SO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission IEC on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The
