ASME MFC-4M-1986 Measurement of Gas Flow by Turbine Meters《用汽轮计测量气体流量》.pdf

1、AN AMERICAN NATIONAL STANDARD Measurement of G8s Flow by Turbine Meters ANSI/ASME MFC-4M-1986 REAFFIRMED 2008 FOR CURRENT COMMITTEE PERSONNEL PLEASE E-MAIL CSasme.org SPONSORED AND PUBLISHED BY THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS United Engineering Center 345 East 47th Street New York, N.Y.

2、 10017 Date of Issuance: July 15, 1986 This Standard will be revised when the Society approves the issuance of a new edition. There will be no addenda or written interpretations of the requirements of this Standard issued to this Edition. This code or standard was developed under procedures accredit

3、ed as meeting the criteria for American National Standards. The Consensus Committee that approved the code or stanaard was balanced to assure that individuals from competent and concerned irtterests have had an oppor tunity to participate. The proposed code or standard was made 1avaj l,able for publ

4、ic review and comment which provides an opportunity for additional public input from industry, academia, reg ulatory agencies, and the 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

5、to the validity of any patent rights asserted in connection with any items mentioned in this document, and does not undertake to insure 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 expr

6、essly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, is entirely their own responsibility . Participation by federal agency representative(s) or person(s) affiliated with industry is not to be interpreted as government or industry e

7、ndorsement of this code or standard. ASME accepts responsibility for only those interpretations issued in accordance with governing ASME procedures and policies which preclude the issuance of interpretations by individual vol unteers. No part of this document may be reproduced in any form, in an ele

8、ctronic retrieval system or otherwise, withou the prior written permission of the publisher. Copyright 1986 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in U.S.A. FOREWORD (This Foreword is not part of ANSI/ASME MFC-4M-1986.) The purpose of this Standard is to provide

9、guidance and recommendation in the application of turbine meters for gas measurement. This Standard was prepared by Subcommittee No. 8 - Turbine Meters, of the ASME Standards Committee on Measurement of Fluid Flow in Closed Conduits. It represents current practice. This Standard on gas turbine meter

10、s complements the following two published American National Standards on liquid turbine meters: (a) ANSI Zll.299-1971 (API Standard 2534), Measurement of Liquid Hydrocarbons by Turbine Meter Systems (b) ANSIIISA-RP31.1-1977, Recommended Practice - Specification, Installation, and Calibration of Turb

11、ine Flowmeters This Standard was approved as an American National Standard on April14, 1986. iii ASME STANDARDS COMMITTEE Measurement of Fluid Flow in Closed Conduits (The following is the roster of the Committee at the time of approval of this Standard.) OFFICERS R. W . Miller, Chairman W. F. Z. Le

12、e, Vice Chairman K. Wessely, Secretary COMMITTEE PERSONNEL R. B. Abernathy, Pratt (2) the measurement of gas by a turbine meter; the meters construction, installation, operation, perfor mance characteristics, data computation and presenta tion, calibration, field checking, and other related con side

13、rations of the meter. (b) This Standard does not apply to: (J) accessory equipment used to measure pressure and temperature, and/or density for the accurate deter mination of mass or base volumes, or those accessories used to automatically compute mass or base volumes; (2) steam metering or two-phas

14、e flow measure ment; (3) applications involving pulsating flow or fluc tuating flows where adverse effects on meter accuracy can be anticipated. 2 SYMBOLS AND DEFINITIONS Much of the vocabulary and many of the symbols used in this Standard are defined in ANSIIASME MFC-1M-1979, Glossary of Terms Used

15、 in the Measurement of Fluid Flow in Pipes. Others that are unique in the field under consideration or with special technical meanings are given in Table 1, and in para. 2.1. Where a term has been adequately defined in the main text, reference is made to the appropriate clause or paragraph. 2. 1 Def

16、initions base flow rate - flow rate calculated from flowing con ditions to base conditions of pressure and temperature base pressure - a specified reference pressure to which a gas volume at flowing conditions is reduced for the purpose of billing and transfer accounting. It is gener ally taken as i

17、4.i:r psia (ioi.560 kPa) by the-gas in dustry in the USA. 3 base temperature - a specified reference temperature to which a gas volume at flowing conditions is reduced for the purpose of billing and transfer accounting. It is generally taken as 60F (15.56C) by the gas industry in the USA. base volum

18、e - volume of the fluid at base pressure and temperature flowing pressure - static pressure of the fluid at the tur bine rotor in actual operation flowing temperature - the temperature of the fluid when passing through the turbine rotor in actual operation meter pressure tap - the pressure tap provi

19、ded and identified by the manufacturer on the meter body to e,n able the metering static pressure at the turbine rotor to be measured rated conditions - conditions of pressure, temperature, and gas composition as specified by manufacturer that rates the meter Reynolds number- a dimensionless paramet

20、er ex pressing the ratio between inertia and viscous forces. It is given by the formula where Vi Re = v V = the average spatial fluid velocity = a characteristic dimension of the system in which the flow occurs v = the kinematic viscosity of the fluid pipe Reynolds number - expressed by the formula

21、where D = diameter of the inlet pipe which is of the same nominal size as the meter VP = average fluid velocity in the inlet pipe“ ANSI/ASME MFC-4M-1986 AN AMERICAN NATIONAL STANDARD TABLE 1 SYMBOLS MEASUREMENT OF GAS FLOW BY TURBINE METERS Symbol Quantity Dimensions Note 1111 U.S. Units Sl Units Fp

22、b Pressure base factor FP, Flowing pressure factor Fpv Supercompressibility factor F,b Temperature base factor F“ Flowing temperature factor G Specific gravity of gas (dry air = 1.001 K Calibration factor N Number of moles of gas p Static absolute pressure p Static gage pressure ilP Meter pressure l

23、oss Q Volume flow rate R Universal gas constant s Compressibility ratio T Absolute temperature v Gas volume passed M Gas mass passed z Compressibility factor p Mass density of gas Subscript Descnption a Atmospheric conditions Dimensionless Dimensionless Dimensionless Dimensionless Dimensionless Dime

24、nsionless L -3 M ML -lr-2 ML -lr-2 ML -lr-2 L 3r-, L 2r-29- 1 Dimensionless (J L3 M Dimensionless ML -3 pulses/ft3 Ibm-mole lbf/ft2 abs lbf/ft2 gage lbf/ft2 ft3/hr ft lbf/(lbm-mole 0R) pulses/m3 mole Pa abs Pa gage Pa m3/s J/(mole K) b Base conditions of temperature, pressure, and gas composition f

25、Flowing conditions of temperature, pressure, and gas composition r Rated conditions of temperature, pressure, and gas composition as specified by manufacturer NOTE: ( 11 Fundamental dimensions: M = mass; L = length; T = time; IJ = temperature turbine meter - velocity measuring device in which the pr

26、imary device is an axial flow type turbine whose ro tating member is driven by the fluid and essentially all the fluid passes through the rotating member 3 CONSTRUCTION 3.1 General The axial flow type gas turbine meter consists ofthree basic components: (a) the body (b) the measuring mechanism (c) t

27、he output and readout device Schematics of axial flow gas turbine meters are shown in Fig. 1. The flow enters the meter and is directed to the annular passage formed by the inlet nose cone and the interior wall of the body. The fluid enters the rotor and, due to the angle of the blades, imparts a fo

28、rce to rotate the blading. The ideal speed of the rotor is di rectly proportional to the flow rate. The actual rotational speed of the rotor is a function of the passageway size and shape, and the rotor design. It is also dependent upon the load that is imposed on the rotor system due 4 to internal

29、mechanical friction , fluid drags, external loading, and fluid density. 3.2 Body The body and all other parts comprising the fluid-con taining structure of a turbine meter are designed to han dle the pressures and temperatures for which they are rated. Body connections should be designed in accordan

30、ce with ANSI flange standards or appropriate threaded con nection standards. Other accepted standards could be used. Bodies should be constructed of any material suit able for the service conditions to be encountered. All components forming the pressure vessel will be hydrostatically pressure tested

31、 to a minimum of 1.5 X the maximum allowable operating pressure. The dura tion of the test shall be in accordance with ANSI Bl6.5 or other recognized, applicable standards. Bodies should be badged or marked to show the man ufacturers name or trademark, serial number, pressure rating, and maximum cap

32、acity in actual volume flow rate units. MEASUREMENT OF GAS FLOW BY TURBINE METERS Inlet_, Nose cone Body Upstream Turbine rotor -statorl Inlet ANSI/ ASME MFC-4M-1986 AN AMERICAN NATIONAL STANDARD Mechanical or electronic readout Mechanism housing and tail cone -. Outlet -End End connection connectio

33、n Outlet b a FIG. 1 SCHEMATIC DRAWINGS OF AXIAL FLOW GAS TURBINE METERS 5 ANSI/ASME MFC-4M-1986 AN AMERICAN NATIONAL STANDARD The body should be clearly and permanently marked with the word INLET on the inlet connection end or an arrow on the body side pointing the direction of flow. 3.3 Measuring M

34、echanism The measuring mechanism consists of the rotor, rotor shafting, bearings, and the necessary supporting struc ture. There are two general mechanism configurations cat egorized by the way they are installed in the meter body : (a) Top or Side Entry Type- the measuring mech anism is removable,

35、as a unit, through a top or side flange without disturbing the end connections (b) End Entry Type- the measuring mechanism is removable, either as a unit or as separate pieces, through the end connections The measuring mechanism should be permanently identified if it is removable as a unit with the

36、following information: (a) mechanism serial number (b) direction of flow if module mounting is reversible 3.4 Output and Readout Device Turbine meters are available with mechanical drive arid/or electrical pulse outputs. For mechanical drive output meters, the output con sists of shafting, gearing,

37、and other drive components needed to transmit the indicated rotor revolutions out side the body for uncorrected (line) volume registration . Meters should be marked near the output shaft to indi cate the direction of rotation and the nominal uncor rected volume per revolution. The intermediate geari

38、ng should be marked with the basic gear ratio, not includ ing the change gears. If used, change gears should be stamped with the size, and the number of teeth. For electrical pulse output meters, the output includes the pulse detector system and all electrical connections necessary to transmit the i

39、ndicated rotor revolutions out side the body for uncorrected volume registration. Me ters should be marked to indicate the proper electrical connections and the number of pulses per unit of uncor rected volume. The readout devices may be of any form suitable for the application. 4 INSTALLATION 4.1 G

40、eneral The turbine meter is a velocity measuring device. The piping configuration immediately upstream of the meter 6 MEASUREMENT OF GAS FLOW BY TURBINE METERS should be such that the flow profile entering the meter has a uniform distribution and is without jetting or swirl. Since the turbine meter

41、construction is designed to di rect the flow to the annular passage upstream of the ro tor, it effectively tends to average the velocity profile of most normal flow conditions, thus minimizing the influ ence of minor flow distortions on meter performance. Straightening vanes are recommended; however

42、, re gardless of location they will not eliminate the effect of strong jetting. Integral straightening vanes installed in the entrance to a meter and a part of the meter design will eliminate minor swirl conditions. Straightening vanes located in the upstream meter piping in accor dance with piping

43、configurations (para. 4.2) will elimi nate most normal flow swirl conditions. The installation of a throttling device such as a reg ulator or partially closed valve is not recommended in close proximity to the meter. Where such installations are necessary, the throttling device should be placed an a

44、dditional eight nominal pipe diameters upstream or an additional two nominal pipe diameters downstream of the installation configuration in Fig. 2, illustrated in para. 4.2. When used in the configurations illustrated in Figs. 3, 4 , and 5, the additional pipe diameters should be added upstream or d

45、ownstream of the vertical riser. Placement of such a device in closer proximity to the meter may result in accuracy degradation and/or re duced bearing life. 4.2 Installation Configurations 4.2.1 Recommended Installation for In-Line Meters. The recommended installation requires a length of 10 nomina

46、l pipe diameters upstream with straight ening vane outlet located at 5 nominal pipe diameters from meter inlet as shown in Fig. 2. A length of 5 nom inal pipe diameters is recommended downstream of the meter. Both inlet and outlet pipe should be of the same nominal size as the meter. 4.2.2 Optional

47、Installations for In-Line Meters. The use of optional installations may result in some deg radation in meter accuracy. The meter manufacturer should be consulted for performance accuracies that could be expected when using an optional installation configuration. (a) Short Coupled Installation. In th

48、ose instances where the required space for the recommended instal lation of Fig. 2 is not available, a short coupled instal lation may be employed. This configuration utilizes about 4 nominal pipe diameters upstream with straight ening vanes located at the inlet of the piping. A typical installation

49、 is shown in Fig. 3. The distance between the straightening vane outlet and the meter inlet should MEASUREMENT OF GAS FLOW BY TURBINE METERS be a minimum of 2 nominal pipe diameters. The meter should be mounted between vertical risers using a stan dard tee or elbow with the block valves, filters, or strainers mounted on the risers. The maximum pipe re duction to the risers is 1 nominal pipe size. (b) Close Coupled Installation. Close coupled instal lation of a gas turbine meter is shown in Fig. 4. The meter design must incorporate integral straightening vanes upstre