ASTM D1066-2018 Standard Practice for Sampling Steam.pdf

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1、Designation: D1066 11D1066 18Standard Practice forSampling Steam1This standard is issued under the fixed designation D1066; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicate

2、s the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This practice covers the sampling of saturated and superheated steam. It is app

3、licable to steam produced in fossil fired andnuclear boilers or by any other process means that is at a pressure sufficiently above atmospheric to establish the flow of arepresentative sample. It is also applicable to steam at lower and subatmospheric pressures for which means must be provided toest

4、ablish representative flow.1.2 For information on specialized sampling equipment, tests or methods of analysis, reference should be made to the AnnualBook of ASTM Standards, Vols 11.01 and 11.02, relating to water.1.3 The values stated in SI units are to be regarded as standard. The values given in

5、parentheses are for informationonly.mathematical conversions to inch-pound units that are provided for information only and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of th

6、is standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in

7、the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2A269 Specification for Seamless and Welded Austenitic Stainless Steel Tub

8、ing for General ServiceA335/A335M Specification for Seamless Ferritic Alloy-Steel Pipe for High-Temperature ServiceD1129 Terminology Relating to WaterD3370 Practices for Sampling Water from Closed ConduitsD5540 Practice for Flow Control and Temperature Control for On-Line Water Sampling and Analysis

9、3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in this practice,standard, refer to definitions given in Practice Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 isokinetic sampling, na condition wherein the sample entering the port (tip) of the sampling

10、nozzle has the same as thevelocity vector (velocity and direction) as the stream being sampled. Isokinetic sampling ensures a representative sample ofdissolved chemicals, solids, particles, chemicals absorbed on solid particles, and in the case of saturated and wet steam, waterdroplets are obtained.

11、3.2.1.1 Discussion1 This practice is under the jurisdiction ofASTM Committee D19 on Water and is the direct responsibility of Subcommittee D19.03 on Sampling Water and Water-FormedDeposits, Analysis of Water for Power Generation and Process Use, On-Line Water Analysis, and Surveillance of Water.Curr

12、ent edition approved June 15, 2011Aug. 1, 2018. Published July 2011August 2018. Originally approved in 1949. Last previous edition approved in 20062011 asD1066 06.D1066 11. DOI: 10.1520/D1066-11.10.1520/D1066-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cust

13、omer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to th

14、e previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright A

15、STM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Isokinetic sampling ensures a representative sample of dissolved chemicals, solids, particles, chemicals absorbed on solid particles,and in the case of saturated and wet steam, water droplets are e

16、xtrtacted from a process stream.3.2.2 sample cooler, na small heat exchanger designed to provide cooling/condensing of small process sampling streams ofwater or steam.3.2.3 sampling, nthe withdrawalextraction of a representative portion of the steam flowing in the boiler drum lead or pipelineby mean

17、s of a sampling nozzle and the delivery of this portion of steam in a representative manner for analysis.3.2.4 saturated steam, na vapor whose temperature corresponds to the boiling water temperature at the particular existingpressure.3.2.5 superheated steam, na vapor whose temperature is above the

18、boiling water temperature at the particular existingpressure.4. Summary of Practice4.1 This practice describes the apparatus, design concepts, and procedures to be used in extracting and transporting samples ofsaturated and superheated steam. ExtractionSampling nozzle selection and application, line

19、 sizing, condensing requirements andoptimization of flow rates are all described. Condensed steam samples should be handled in accordance with Practices D3370 andD5540.5. Significance and Use5.1 It is essential to sample steam representatively extract and transport steam in a manner that provides th

20、e most representativesample of the process steam in order to accurately determine the amount of all impurities (dissolved chemicals, solid particles,chemicals absorbed on solid particles, water droplets) in it (1).3 An accurate measure of the purity of steam provides information,whichinformation tha

21、t may be used to determine whether the purity of the steam is within necessary limits to prevent damage ordeterioration (corrosion, solid particle erosion, flow-accelerated corrosion, and deposit buildup) of downstream equipment, suchas turbines. Impurities turbines and process heat exchangers. The

22、sources of impurities in the steam may be derived from caninclude boiler water carryover, inefficient steam separators, natural salt solubility in the steam and other factors. The mostcommonly specified and analyzed parameters are sodium, silica, iron, copper, and cation conductivity.6. Hazards6.1 T

23、he transport of steam samples may present high temperature and/or high pressure safety concerns that should be consideredand addressed based upon local (site) requirements.7. Interferences7.1 Sampling of steam presents difficult extraction and transport problems that affect the representativeness of

24、 the sample.Isokinetic sampling requires that the velocity vector (velocity and direction) of the fluid entering the sample nozzle port (tip) bethe same as the stream being sampled at the location of the sample nozzle. When the sample is not extracted isokinetically thecontaminants in the steam are

25、not properly represented in the sample. The effects of non-isokinetic sampling are illustrated in Fig.1 and can make the sample unrepresentative. The sample should be removed at a position away from the pipe wall, located at apoint of average velocity which can be calculated for both laminar and tur

26、bulent flows.7.2 Saturated SteamSampling of Traditionally, saturated steam samples with initial steam velocities above 11 m/s (36 ft/s)were considered to provide adequate turbulent flow to ensure transport of most particulates and ionic components. More recentstudies (2, 3)steam presents difficult e

27、xtraction and transport problems found that because many sample lines are long anduninsulated, steam samples are frequently fully condensed prior to reaching the sample station. Partially or fully condensedsamples usually have a velocity too low to prevent excessive deposition and the sample becomes

28、 nonrepresentative of the source.This condensation can result in long sample lag times (time between the sample entering the sampling nozzle to when it reachesthe sample panel) measured in minutes and hours instead of seconds. Detailed design of the sample line to control vapor and liquidvelocity ca

29、n minimize this interference but cooling of saturated steam samples at the source is recommended to assure arepresentative sample. See Practices D3370 and D5540that affect the representativeness of the sample. for further information onfactors that affect liquid sample transport.6.1.1 Isokinetic sam

30、pling requires that the velocity vector (velocity and direction) of the fluid entering the sample nozzle port(tip) be the same as the stream being sampled at the location of the sample nozzle. When the sample is not extracted isokineticallythe contaminants in the steam are not properly represented i

31、n the sample. The effects of non-isokinetic sampling are illustrated inFig. 1 and can make the sample unrepresentative. The sample should be removed at a position away from the pipe wall, locatedat a point of average velocity which can be calculated for both laminar and turbulent flows.3 The boldfac

32、e numbers given in parentheses refer to a list of references at the end of this standard.D1066 1826.1.2 Traditionally, saturated steam samples with initial steam velocities above 11 m/s (36 ft/s) were considered to provideadequate turbulent flow to ensure transport of most particulates and ionic com

33、ponents. More recent studies (2,3) found that becausemany sample lines are long and uninsulated, steam samples are frequently fully condensed prior to reaching the sample station.Partially or fully condensed samples usually have a velocity too low to prevent excessive deposition and the sample becom

34、esnonrepresentative of the source. Detailed design of the sample line to control vapor and liquid velocity can minimize thisinterference but cooling of saturated steam samples at the source is recommended to assure a representative sample. See PracticesD3370 and D5540 for further information on fact

35、ors that affect liquid sample transport.7.3 Superheated SteamMost contaminants can be dissolved in superheated steam. However, as steam pressure andtemperature are reduced the solubility of many contaminants is decreased and the contaminants precipitate and deposit on the innersurfaces of the sample

36、 line (4). This condition has been found to be prevalent only in regions of dry wall tube where thetemperature of the tube wall exceeds the saturation temperature of the steam.7.3.1 Interference also occurs when the transport tube temperature is at or below the saturation temperature. The steam lose

37、ssuperheat and dissolved contaminants deposit on the tube wall. The sample is no longer representative. Superheated steam samplesshall be cooled or desuperheated in the sample nozzle or immediately after extraction to ensure a representative sample. Coolingthe sample within the sample nozzle may cau

38、se thermal fatigue. All necessary precautions should be taken. Seefatigue and is notrecommended and could affect 7.1.3.4 andthe composition 7.2.4.of the sample.8. Procedure8.1 This practice concerns equipment design only and not operating procedures.9. Materials and Apparatus9.1 Extracting the Sampl

39、e:9.1.1 Saturated SteamSince saturated steam isSaturated and superheated steam are normally sampled as a two-phase fluid,made up of steam two-phase fluids (steam and small droplets of water, water or steam and particulate) requiring isokinetic samplingshallto be employed. Since steam velocities vary

40、 with boiler load it normally is not practical to sample isokinetically throughoutthe load range. Normally, the load of interest is full load or a guaranteed overload. The sampling system shall be designed toprovide isokinetic sampling at this design load.under the most critical load conditions. Onc

41、e the sampling nozzle is designed, theisokinetic sampling rate is directly proportional to the mass flow rate of the process stream and independent of operating pressure.7.1.1.1 At low velocities, the moisture in wet steam forms a film along the inside surface of the steam line that entrainsimpuriti

42、es (5). Samples should be extracted at a position away from the pipe wall (Fig. 2). See 7.1.3.1.9.1.2 Saturated SteamAt low velocities, the moisture in wet steam forms a film along the inside surface of the steam line thatentrains impurities (5). Samples should be extracted at a position away from t

43、he pipe wall (Fig. 2). See 9.1.4.5.FIG. 1 Effect of Non-Isokinetic SamplingD1066 1839.1.3 Superheated SteamParticulates are often present in superheated steam and these particulates can contain soluble species(Na, Cl, SO4) that are of interest and should be sampled (1,6, 6-87). Therefore, an isokine

44、tic sampling nozzle should be used forsampling superheated steam in order to obtain a representative sample of both the gas and solid phases.7.1.2.1 Because the dissolved contaminants in high pressure superheated steam deposit on the inner surfaces of the nozzle andsample lines as the sample desuper

45、heats, superheated steam samples shall be rapidly desuperheated or condensed near the pointof extraction. See 7.2.4.9.1.4 Sampling NozzlesStratification of suspended solids in horizontal steam pipes can influence the composition of the steamsamples. To minimize the effects of stratification it is re

46、commended that steam sampling nozzles be located in long vertical pipes.To ensure that all water droplets are carried in the flow stream, downward flow is preferred. Nozzles which must be located in ahorizontal pipe should be near the top of The design of a steam sampling system should start with th

47、e design of the isokineticsampling nozzle. The sampling nozzle design will determine the requirements for the isolation valves and sample line from thesampling nozzle to the primary sample cooler/condenser. The design isokinetic sampling rate should be determined by therequirements of Practices D337

48、0 and the pipevolume (of2,7) . Ideally, the nozzle should be installed at least 35 internal pipediameters downstream and 4 internal pipe diameters upstream of any flow disturbance (elbow, tee, valve, orifice, etc.). If this isnot possible, the sample needed for on-line analyzers and grab samples. Th

49、is value is typically between 1000 and 1200 cc/min(condensed). For applications where the mass flow rate in the process pipe changes significantly during different modes ofoperation, the sampling nozzle should be installed so that the ratio of its distance from the upstream disturbance to the downstreamdisturbance is about 9:1.designed to provide a representative sample for the most critical process conditions or the typical operatingconditions.9.1.4.1 Nozzles are most frequently located at a distance from the pipe wall where the actual velocity equals the average