1、 EJECTORS I TEST PERFORMANCE I CODES :,“-.“- I 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 ENGINEERS Copyright O 1976 by All Rights Reserved Printed i
2、n U.S.A. FOREWORD The Performance Test Codes Committee of The American Society of Mechanical Engineers recognized the need for a test code covering steam jet ejectors. Accordingly, in 1948, Performance Test Code Committee No. 24 was organized to prepare such a code. The testing of steam jet ejectors
3、 had been covered to some extent previously in the test code covering surface condensers. The special problems involved in ejector testing and the fact that ejectors find their greatest application in industrial process fields rather than in the power plant, required a separate code for this type of
4、 equipment. The original Code was approved by the Performance Test Codes Committee in May, 1956 and adopted by the Council as a standard practice of the Society by the action of the Board on Codes and Standards in June, 1956. In October, 1969, Performance Test Code Committee No. 24 was reorganized f
5、or the purpose of preparing a revised Code which would be more applicable to the art in its present state of development. This revised Code includes ejectors operated with motive fluids other than steam and was approved by the Performance Test Codes Cornmittee on September 26, 1975 and adopted by th
6、e Council as a standard practice of the Society by action of the Policy Board on Codes and Standards on November 17,1975. On February 24,1976, the Board of Standards Review of the American National Standards Institute approved PTC 24 - Ejectors as an American National Standard. . 111 ASME PTC*2L1 76
7、 0759670 0053363 T W PERSONNEL OF PERFORMANCE TEST CODE COMMITTEE NO. 24 ON EJECTORS Gustave R. Haun, Chairman John L. Knoble, Vice Chairman Richard M. Persyn, Secretary William M. Bell, President, NIcKinlay Engineering, Inc., Sudbury, Massachusetts 01776 Theodore B. Braun, Senior Engineer, The Dow
8、Chemical Company, 47 Building, Midland, Michigan 48640 Cornelius C. Dunn, Project Engineer, Pennwalt Corporation, 5500 Tabor Road, Philadelphia, Pennsylvania 19120 Leslie L. Foster, Senior Consulting Engineer, Condenser Division, Ingersoll Rand Company, Memorial Parkway. Phillipsburg, New Jersey 088
9、65 Gustave R. Haun, Manager, Product Development, Schutte the work of compression being done by the kinetic energy of the motive fluid issuing from a nozzle at high velocity. 0.02 The basic unit consists of a nozzle, a suction chamber, and a diffuser. A single assembly of these parts is known as a s
10、tage, see Fig. 13:Two or more stages may be used in series, varying with the compression ratio, and the combination is referred to as a multi-stage unit. Con- denser(s) may be used between stages. The term “ejec- tor system”as used herein refers to the complete ejector assembly which may be either a
11、 single stage, or a number of stages, including their respective condenser(s). 0.03 The motive fluid most commonly used in the ejector is steam. Other fluids, such as air and hydrocarbon gases, have application in the process industries. . 0.04 Of the suction fluids handled-by ejectors, air, steam,
12、and air-vapor mixtures predominate. The pump- ing of hydro-carbon gases and many other chemicals is not uncommon. The suction pressures, usually below atmosphere, vary widely with the application, and occasionally extend to the low absolute pressure ranges measured in microns. 0.05 There are several
13、 test problems peculiarly related to the ejector. The measurement of relatively small flow rates and low absolute pressures requires a special technique. Because of the critical relation be- tween motive-fluid pressure and the stability of the ejector operation, a specific procedure is required to e
14、stablish acceptable test conditions. This Code provides the necessary instructions. 0.06 Reference is made to the Performance Test Code Supplements on Instruments and Apparatus (ab- breviated as I i.e. the relation of pressure a stipulated pressure and temperature motive fluid pressure or the discha
15、rge pressure to breakdown and recovery of the pumping action 1 .O3 The Code rules and procedures are intended primarily for the test of ejectors in which the motive fluid is steam. They may be used, however, with any motive fluid for which the physical properties are com- pletely and reliably known.
16、 See Section 3, Par. 3.01. 1 .O4 The instructions and capacity measurements provide for tests where the suction fluid pumped is air, water vapor, or other gases for which the physical and thermodynamic properties are known. A procedure is provided for tests on gas mixtures in which the compo- nents
17、can be separately measured and controlled. 1 .O5 If the motive fluid is steam or other condensable vapor, it shall be dry (without any moisture). The Code does not cover two-phase fluids. 1 .O6 This Code is limited to ejectors having suction pressures that permit accurate measurement by the instrume
18、ntation and technique available. 1 .O7 Rules are given for adjusting test results to design conditions. (See Section 3 on Guiding Principles.) 1.08, This Code does not consider an overall tolerance or margjn which may, by agreement, be made applicable to any specific performance. Allowances for inac
19、curacy of measurements may be recognized as pro- vided in Section 3, Par. 3.10. 1 .O9 The procedures and instrument specifications of Section 4, the formulae and methods for computing results of Section 5, and the indicated form of reporting the test of Section 6, are mandatory. For reasons of exped
20、iency or otherwise, the parties to a code test may, by agreement, substitute other instruments or methods. However, only tests made in strict accordance with the mandatory provision of this Code may be designated as complying with the ASME Test Code for Ejectors. 2 EJECTORS SECTION 2, DESCRIPTION AN
21、D DEFINITION OF TERMS 2.01 Absolute Pressure is the pressure measured from absolute zero; i.e., from an absolute vacuum. It equals the algebraic sum of the atmospheric pressure and the gage pressure. 2.02 Static Pressure is the pressure measured in the gas in such manner that no effect on the measur
22、ement is produced by the velocity of the gas. 2.03 Total Pressure is the pressure measured at the . stagnation point when a moving gas stream is brought to rest and its kinetic energy is converted by an isentropic compression from the flow condition to the stagnation pressure. It is the pressure usu
23、ally measured by an impact tube. In a stationary body of gas, the static and total pressures are numerically equal. 2.04 Velocity Pressure is the total pressure minus the static pressure in a gas stream. It is generally measured by the differential reading of a Pitot tube. 2.05 Suction Pressure is t
24、he static pressure prevailing at the suction inlet of the ejector expressed in absolute units. 2.06 Discharge Pressure is the static pressure pre- vailing at the discharge of the ejector expressed in absolute units. 2.07 Motive-Fluid Pressure is the static pressure prevailing at the nozzle inlet exp
25、ressed in absolute units. 2.08 Total Temperature is that temperature which would be measured at the stagnation point if a gas stream were brought to rest and its kinetic energy con- verted by an isentropic compression from the flow condition to the stagnation temperature. 2.09 Suction Temperature is
26、 the temperature of the fluid at the suction inlet of the ejector. 2.10 Motive-Fluid Temperature is the temperature of the motive fluid at the nozzle inlet. 2.1 1 Stability is used in this Code to describe a characteristic of the ejector pumping action. If the dis- charge pressure is too high, or if
27、 the motive-fluid pres- sure is too low, the flow stream at the suction may momentarily reverse and the ejector is said to be un- stable. Stable operation is identified as that condition at which the suction pressure is not decreased by either a further decrease in the discharge pressure or a furthe
28、r increase in the motive-fluid pressure. The term does not necessarily apply to single-stage ejectors designed for very low compression ratios nor to multistage ejectors working at suction pressures above their normal range. 2.12 Breaking Pressure is that pressure of either the motive fluid or the d
29、ischarge which causes the ejector to become unstable. 2.13 Recovery Pressure (Pick-up Pressure) is that pressure of either the motive fluid or the discharge at which the ejector recovers to a condition of stable operation. 2.14 Specific Weight or Density is the weight of fluid per unit volume under
30、specified conditions of pressure and temperature. 2.15 Specific Gravity is the ratio of the specific weight of gas to that of dry air at standard pressure and temperature. Actual and standard temperatures and pressures must be specified. 2.1 6 Capacity is the weight-ratesf-flow of the fluid compress
31、ed and discharged by the ejector. It refers specifically to the stream of gas pumped through the suction inlet of the ejector. 2.17 Motive-Fluid Consumption, for steam or other fluids, is the weight-ratesf-flow passing through the motive nozzle(s) at specified conditions of temperature and pressure.
32、 3 . . . I . _. . ASME PTC824 76 W 0753b70 0053Lbb 3 m ASME PERFORMANCE TEST CODES SECTION 3, GUIDING PRINCIPLES 3.01 Items on Which Agreement Shall Be Reached. A procedure mandatory in the use of this Code, requires the parties to the test to reach agreement on several items related to the test. Th
33、ese are: The responsibility for obtaining and installing the instruments and controls which are required to conform to this Code. The responsibility for isolation of the equip-, ment to be tested. Method of testing multi-component systems. This Code permits testing ejectors in either of the followin
34、g ways: (i) as a completely assembled unit with all inter-condensers, usually at plant site. (ii) by testing the ejector stages separately with agreement reached as to the match- ing properties, usually done at the manu- facturers testing facilities. Note: While section (ii) is often used, section (
35、i) Intent of specifications as to operating condi- tions. Object of test and required measurements. Range of capacity and stability tests required of the system. The fluid(s) to be used in capacity measure- ment. Method of maintaining constant test condi- tions such as motive pressure, cooling-water
36、 rate, etc. Method of measuring the flow rates of the suction and motive fluids. Selection of test arrangement as provided here- in to suit the type of ejector(s), the kind of fluids to be measured, and the operating conditions. The selection of instruments. Arrangements for calibration of the instr
37、uments and fluid meters where required. Arrangements for examination of the system, for preliminary tests, and the time interval be- tween the initial use in service and the code- test. This item is of particular interest if sur- face condensers are involved. If a condenser, silencer, or other equip
38、ment follows the last ejector stage, agreement shall be reached regarding the location of stations for measuring the discharge pressure of the preced- ing ejector stage. shall control if any discrepancies arise. 3.02 Parties to the test shall designate a person to direct the test and serve as arbite
39、r in regard to the ac- curacy of observations, or reliability of the operating procedures. 3.03 Representatives of any interested party may, if they so desire, be present at all times during the test to assure themselves that the test is being conducted in ac- cordance with this Code and with any ag
40、reement made in advance, 3.04 During preparation for test and before starting any test run, the ejector system shall be placed at the disposal of all interested parties for examination. Dimen- sions and physical condition, not only of ejector(s) and related equipment, but of all the associated syste
41、m which may be required in the determination of perform- ance, shall be observed and recorded. After examination and prior to test, the party conducting the test may allow any necessary permanent adjustments to be made to place the ejector system in the proper operating condition.* 3.05 Alternate ar
42、rangements of the flow nozzles are provided for the measurement of capacity as described in Section 4. Other methods of flow measurement are given in “Fluid Meters,” sixth edition. 3.06 Agreement shall be reached as to the effect of the suction fluid on the entire system if the suction fluid is othe
43、r than the design composition. Tests using suction fluid other than the design composition, will re- quire evaluation of the effect on the ejector system as a whole. This must include the effect on condenser operating conditions. 3.07 Tests made to establish a single-point capacity shall consist of
44、not less than three load points and they shall bracket the rated value within f 5 percent of rated capacity. It is recommended that a capacity curve be generated which runs from no load to a load which causes the suction pressure to rise sharply; this is not mandatory. 3.08 The methods of determinin
45、g stability are given in 4.32, Operating Procedure. 3.09 lf cooling water is required, the supply pressure shall be free of fluctuation. Facilities shall be provided for controlling the cooling-water quantity and tempera- ture at the specified values. Cooling-water quality (in- cluding gas content,
46、solid content and any foam produc- ing contaminants) shall be suitable for test. 4 *Exercise care not to void any guarantees. - ASflE PTC*k24 76 0757670 0053367 0 m EJECTORS 3.10 The ASME Performance Test Codes shall not recognize commercial tolerances which might be applied to the results of tests.
47、 The codes shall recognize, how- ever, limits of error of any of the individual measure- ments or methods of a measurement (Part III, Section I of PTC 1). If any such limits of error are agreed upon, their numerical value and the method of their applica- tion to the test result shall be stipulated e
48、ither in the purchase contract or agreed upon before acceptance tests are commenced and shall be completely described in the test report. 3.1 1 Preliminary Tests. Preliminary tests may be run (a) Determining whether the ejector and associated for the purpose of: piping system are in suitable conditi
49、on for the conducting of a code test. (b) Checking of instruments. (c) Training personnel in the operation of the (d) Determining the conditions of stable operation. 3.1 2 A preliminary test may become the final code test if all of the requirements for a code test were met and it is so agreed by the. interested parties. ejector system. 3.1 3 Test Conditions. The significant factors to be considered in the planning of a test or for appraising the results are: (a) Suction pressure (b) Suction temperature (c) Discharge pressure (d) Suction-fluid composition (e) Suct
