1、 Reference number ISO/TR 11583:2012(E) ISO 2012TECHNICAL REPORT ISO/TR 11583 First edition 2012-04-01 Measurement of wet gas flow by means of pressure differential devices inserted in circular cross-section conduits Mesurage du dbit de gaz humide au moyen dappareils dprimognes insrs dans des conduit
2、es de section circulaire ISO/TR 11583:2012(E) COPYRIGHT PROTECTED DOCUMENT ISO 2012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permissi
3、on in writing from either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2012 All rights reserved
4、ISO/TR 11583:2012(E) ISO 2012 All rights reserved iiiContents Page Foreword iv Introduction . v 1 Scope 1 2 Normative references 1 3 Terms and definitions . 2 4 Symbols and subscripts . 2 5 Principle of the method of measurement and computation . 2 5.1 Principle of the method of measurement 2 5.2 Co
5、mputation 4 6 Venturi tubes 5 6.1 General . 5 6.2 Design requirements . 5 6.3 Pressure tappings . 5 6.4 Computation of gas flowrate 6 6.5 Uncertainties 8 7 Orifice plates 9 7.1 General . 9 7.2 Design requirements . 9 7.3 Use of orifice plates with drain holes 9 7.4 Pressure tappings . 9 7.5 Computat
6、ion of gas flowrate 10 7.6 Uncertainties 12 8 Tracer techniques 12 8.1 General . 12 8.2 Technique . 13 8.3 Measuring the gas flowrate using tracer techniques 13 9 Comparison method 14 10 Total mass flowrate known 14 11 Using a throttling calorimeter 15 12 Installation 15 12.1 Flow conditioners 15 12
7、.2 Insulation 15 12.3 Pressure tappings and impulse lines 15 12.4 Gas composition . 16 12.5 Densitometers 16 13 Sampling 17 13.1 General . 17 13.2 Sampling points at the wet-gas meter . 17 13.3 Sampling points at test separators . 17 Annex A (informative) Calculations 18 Bibliography 25 ISO/TR 11583
8、:2012(E) iv ISO 2012 All rights reservedForeword 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 ISO technical committees. Each member bo
9、dy 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 Electrot
10、echnical 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 main task of technical committees is to prepare International Standards. Draft International Standards adopted b
11、y the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which
12、is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides a
13、re considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TR 11583 was prepared by Technical Committee ISO/T
14、C 30, Measurement of fluid flow in closed conduits, Subcommittee SC 2, Pressure differential devices. ISO/TR 11583:2012(E) ISO 2012 All rights reserved vIntroduction ISO 5167-1:2003, ISO 5167-2:2003, and ISO 5167-4:2003 include specifications for Venturi tubes and orifice plates, but are applicable
15、only where the fluid can be considered as a single phase and the conduit is running full. If the fluid being measured is a wet gas there is an overreading which can be corrected using suitable wet-gas correction equations. TECHNICAL REPORT ISO/TR 11583:2012(E) ISO 2012 All rights reserved 1Measureme
16、nt of wet gas flow by means of pressure differential devices inserted in circular cross-section conduits 1 Scope This Technical Report describes the measurement of wet gas with differential pressure meters. It applies to two-phase flows of gas and liquid in which the flowing fluid mixture consists o
17、f gas in the region of 95 % volume fraction or more (the exact limits on the mixture are defined in 6.4.3, 6.4.5, 7.5.3 and 7.5.5). This Technical Report is an extension of ISO 5167. The ranges of gases and liquids from which the equations in this Technical Report were derived are given in 6.4.1 and
18、 7.5.1. It is possible that the equations do not apply to liquids significantly different from those tested, particularly to highly viscous liquids. Although the over-reading equations presented in this Technical Report apply for a wide range of gases and liquids at appropriate gas-liquid density ra
19、tios, evaluating gas flowrates depends on information in addition to that required in single-phase flow: under certain conditions, a measurement of the pressure loss is sufficient; tracers can be used to measure the liquid flow; the total mass flowrate may be known (this is more likely in a wet-stea
20、m flow than in a natural gas/liquid flow); in a wet-steam flow a throttling calorimeter can be used. Wet-gas measurement using Venturi tubes or orifice plates is covered in this Technical Report. This Technical Report is only applicable to wet gas flows with a single liquid and is not intended for t
21、he oil and gas industry. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced docu
22、ment (including any amendments) applies. ISO 2186, Fluid flow in closed conduits Connections for pressure signal transmissions between primary and secondary elements ISO 4006, Measurement of fluid flow in closed conduits Vocabulary and symbols ISO 5167-1:2003, Measurement of fluid flow by means of p
23、ressure differential devices inserted in circular cross-section conduits running full Part 1: General principles and requirements ISO 5167-2:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full Part 2: Orifice plates ISO 5
24、167-4:2003, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-section conduits running full Part 4: Venturi tubes ISO/TR 15377, Measurement of fluid flow by means of pressure-differential devices Guidelines for the specification of orifice plates, nozzles
25、 and Venturi tubes beyond the scope of ISO 5167 ISO/TR 11583:2012(E) 2 ISO 2012 All rights reserved3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 4006, ISO 5167-1 and the following apply. 3.1 stratified flow common regime in horizontal pipes at low
26、gas velocities (typically 5 m/s or less) in which the free liquid runs along the bottom of the pipe with the gas flowing at the top of the pipe 3.2 annular flow flow regime that in horizontal pipes occurs at medium gas velocities (typically 5 m/s to 15 m/s) in which the liquid flows around the pipe
27、wall with the gas flowing through the centre of the pipe NOTE In horizontal pipes, annular flow is not uniform; owing to gravitational effects, the liquid is present in higher quantities around the wall at the bottom of the pipe than higher up the pipe wall. 3.3 mist flow flow regime that in horizon
28、tal pipes requires high gas velocities (typically 15 m/s or higher) to keep the liquid suspended in the gas and describes liquid in the flow being carried along in small-droplet form within the body of gas 3.4 slug flow flow regime in which liquid travels along the pipe intermittently but in signifi
29、cant quantity, often due to the liquid becoming trapped in the flow line, for example at the bottom of a vertical pipe or when the flow is started after shutdown 3.5 liquid volume fraction LVF ratio of the liquid volume flowrate to the total volume flowrate, where the total volume flowrate is the su
30、m of the liquid volume flowrate and the gas volume flowrate, all volume flowrates being at actual (not standard) conditions 3.6 gas volume fraction GVF ratio of the gas volume flowrate to the total volume flowrate, where the total volume flowrate is the sum of the liquid volume flowrate and the gas
31、volume flowrate, all volume flowrates being at actual (not standard) conditions 4 Symbols and subscripts See Table 1. 5 Principle of the method of measurement and computation 5.1 Principle of the method of measurement The principle of the method of measurement using differential-pressure meters is b
32、ased on the installation of a primary device (such as an orifice plate or a Venturi tube) into a pipeline. The installation of the primary device causes a pressure difference between the upstream side and the throat or downstream side of the device. The flowrate can be determined from the measured v
33、alue of this pressure difference and from the knowledge ISO/TR 11583:2012(E) ISO 2012 All rights reserved 3of the characteristics of the flowing fluid as well as the circumstances under which the device is being used. It is assumed that the device is geometrically similar to one on which calibration
34、 has been carried out and that the conditions of use are the same, i.e. that it is in accordance with ISO 5167-2 or ISO 5167-4. Table 1 Symbols Symbol Quantity Dimension aSI Unit C Coefficient of discharge dimensionless 1 C ChChisholm coefficient dimensionless 1 C fluidConcentration of tracer in flu
35、id dimensionless 1 d Diameter of orifice or throat of Venturi tube at working conditions L m D Upstream internal pipe diameter (or upstream diameter of a Venturi tube) at working conditions L m Fr gasGas densiometric Froude number see Equation (3) dimensionless 1 g Acceleration due to gravity LT 2m/
36、s 2h Specific enthalpy L 2 T 2J/kg H Function of the surface tension of the liquid (see 6.4.3) dimensionless 1 L downDistance between the downstream end of the Venturi tube divergent section (measured from the end of the cone not the flange) and the downstream pressure tapping used to measure the pr
37、essure loss L m p Absolute static pressure of the fluid ML 1 T 2Pa q mMass flowrate MT 1kg/s q VVolume flowrate L 3 T 1 m 3 /st Temperature of the fluid C X Lockhart-Martinelli parameter see Equation (2) dimensionless 1 Diameter ratio: = d/D dimensionless 1 p Differential pressure ML 1T 2Pa Pressure
38、 loss (without correction for the pressure loss that would have taken place if the Venturi tube or orifice plate had not been present) ML 1T 2Pa Absolute uncertainty b b Expansibility expansion factor dimensionless 1 Isentropic exponent dimensionless 1 Density of the fluid (subscript 1 denotes the v
39、alue at the upstream tapping plane) ML 3kg/m 3 Over-reading correction factor see Equation (1) dimensionless 1 aL length; M mass; T time; temperature. bThe dimensions and units are those of the corresponding quantity.ISO/TR 11583:2012(E) 4 ISO 2012 All rights reservedIn a wet gas flow the gas flowra
40、te is determined by evaluating an over-reading. The over-reading is due to the mass of liquid passing through the primary device. The over-reading is affected by the flow regime, which in a wet gas flow is generally stratified, annular or mist, although, in practice, wet gas flows may be a combinati
41、on of these flow regimes. Other flow regimes can occur intermittently, particularly the slug flow regime if liquid has become trapped in the flow line, for example at the bottom of a vertical pipe. Combinations of line conditions, pipe orientations, and gas-liquid ratios influence the type of flow r
42、egime present. An appreciation of which, if any, flow regime is likely to prevail can be extremely useful. The application of the same wet-gas measurement technique can produce widely different results depending on which flow regime predominates, and knowledge of the likely flow regime can therefore
43、 influence the correct choice of measurement principle to be applied. NOTE Even in a horizontal pipe, liquid can be held-up by gas flows of 1 m/s or less and can remain almost stationary rather than flow with the gas. 5.2 Computation The gas mass flowrate, q m,gas , is given by 1 ,gas 2 ,gas 4 2 4 1
44、 m p C qd (1) where C is given in 6.4.2 or 7.5.2 as appropriate; is determined from the appropriate part of ISO 5167; 1,gas is the upstream gas density; is the over-reading correction factor. NOTE In evaluating , the actual values of p 1and p 2measured in wet gas are used. Factor depends on the prim
45、ary device, on the gas-liquid density ratio, 1,gas / liquid , where liquidis the density of the liquid, on the Lockhart-Martinelli parameter, X, as defined in Equation (2): 1,gas ,liquid ,gas liquid m m q X q (2) and on the gas densiometric Froude number, Fr gas , as defined in Equation (3): ,gas 1
46、,gas gas 2 liquid 1 ,gas 1 ,gas 4 m q Fr Dg D (3) where g is the acceleration due to gravity and q m,liquidis the liquid mass flowrate. ISO/TR 11583:2012(E) ISO 2012 All rights reserved 56 Venturi tubes 6.1 General Venturi tubes are widely used for wet-gas applications. Among their advantages are: a
47、) they do not dam the flow (unlike orifice plates); b) they can be operated at higher differential pressures than orifice plates without incurring permanent meter damage differential pressures up to and above 2 bar (200 kPa) can be contemplated; for a fixed gas mass flowrate the presence of liquid m
48、ay greatly increase the differential pressure; c) therefore, they have a relatively high turndown (typically 10:1) when used with suitably ranged differential pressure transmitters. 6.2 Design requirements The design requirements for Venturi tubes are specified in ISO 5167-4. However, special attent
49、ion should be paid to the following: the finish of the Venturi tube internal surface, which should be smooth and free from machining defects including burrs and ridges; the pressure tappings, which at the point of entry into the meter internal bore should have sharp edges and be free from burrs and wire edges; and the edge of the conical inlet, which should be sharp and free from manufacturing defects. The equation
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