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1、BRITISH STANDARD BS EN ISO 6326-3:1998 BS 3156-11.4.3: 1994 Incorporating Amendment No. 1 to BS 3156-11.4.3:1994 (renumbers the BS as BS EN ISO 6326-3: 1998) Natural gas Determination of sulfur compounds Part 3: Determination of hydrogen sulfide, mercaptan sulfur, and carbonyl sulfide sulfur by pote
2、ntiometry ICS 75.060 Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 6326-3:1998 This British Standard, having been prepared under the direction of the Materials and Chemicals Sector Board (I/-), was published under the authority o
3、f the Standards Board and comes into effect on 15 December 1994 BSI 04-1999 The following BSI references relate to the work on this standard: Committee reference PTI/15 Special announcement in BSI News, September 1994 ISBN 0 580 23614 5 Committees responsible for this British Standard The preparatio
4、n of this British Standard was entrusted to Technical Committee PTI/15, Natural gas and gas analysis upon which the following bodies were represented: AEA Technology British Coal Corporation British Compressed Gases Association British Gas plc British Glass Manufacturers Confederation Chemical Indus
5、tries Association Department of Trade and Industry (Gas and Oil Measurement Branch) Department of Trade and Industry (National Physical Laboratory) Institute of Petroleum Institution of Gas Engineers Sira Limited Society of Chemical Industry Society of Glass Technology Amendments issued since public
6、ation Amd. No.DateComments 9993June 1998Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 6326-3:1998 BSI 04-1999i Contents Page Committees responsibleInside front cover National forewordii Forew
7、ord2 1Scope3 2Normative references3 3Principle3 4Reagents and materials3 5Apparatus3 6Sampling4 7Procedure4 8Expression of results5 9Test report6 Figure 1 Test apparatus5 Figure 2 Example of a titration curve6 Table 1 Precision data7 List of referencesInside back cover Licensed Copy: sheffieldun she
8、ffieldun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS EN ISO 6326-3:1998 ii BSI 04-1999 National foreword This British Standard has been prepared by Technical Committee PTI/15, and is the English language version of EN ISO 6326-3:1997 Natural gas Determination of sulfur com
9、pounds Part 3: Determination of hydrogen sulfide, mercaptan sulfur and carbonyl sulfide sulfur by potentiometry, published by the European Committee for Standardization (CEN). It is identical with ISO 6326-3:1989, published by the International Organization for Standardization (ISO). ISO 6326-3 was
10、prepared by Technical Committee 158, Analysis of gases, in which the United Kingdom participated. BS EN ISO 6326-3 retains the secondary identifier BS 3156-11.4.3, so that it remains cross-referenced within the BS 3156 series of standards. Each Subsection of Section 11.4 of BS 3156 is identical with
11、 the corresponding Part of ISO 6326, and Section 11.4 of BS 3156 consists of the following Subsections: In the United Kingdom the preferred method is that given in Subsection 11.4.4 of BS 3156. The flame photometric detector is available from most manufacturers of chromatographs, both laboratory and
12、 process units, and is applicable to any sulfur compound. By contrast, the electrochemical detector is available from a single supplier and is operated under completely different conditions in order to measure carbonyl sulfide, to those used for all other sulfur compounds. A British Standard does no
13、t purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Subsection 11.4.1 Subsection 11.4.2 Subsection 11.4.3 (BS EN ISO 63
14、26-3) Subsection 11.4.4 Subsection 11.4.5 (BS EN ISO 6326-5) Introduction Odoriferous sulfur compounds by gas chromatography using an electrochemical detector Hydrogen sulfide, mercaptan sulfur, and carbonyl sulfide sulfur by potentiometry Hydrogen sulfide, carbonyl sulfide and sulfur-containing odo
15、rants by gas chromatography using a flame photometric detector Lingener combustion method Cross-reference Publication referred toCorresponding British Standard ISO 1042:1983BS 1792:1982 Specification for one-mark volumetric flasks Summary of pages This document comprises a front cover, an inside fro
16、nt cover, pages i and ii, the EN title page, pages 2 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffiel
17、dun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 6326-3 December 1997 ICS 75.060 Descriptors: Natural gas, gas analysis, determination of content, sulfur, potentiometric methods English version Natural gas Determination
18、of sulfur compounds Part 3: Determination of hydrogen sulfide, mercaptan sulfur and carbonyl sulfide sulfur by potentiometry (ISO 6326-3:1989) Gaz naturel Dtermination des composs soufrs Partie 3: Dtermination du sulfure dhydrogne, des thiols et du sulfure de carbonyle par potentiomtrie (ISO 6326-3:
19、1989) Erdgas Bestimmung von Schwefelverbindungen Teil 3: Bestimmung von Schwefelwasserstoff, Mercaptanschwefel und Kohlenstoffoxidsulfidschwefel durch Potentiometrie (ISO 6326-3:1989) This European Standard was approved by CEN on 6 November 1997. CEN members are bound to comply with the CEN/CENELEC
20、Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN m
21、ember. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN memb
22、ers are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normali
23、sation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref. No. EN ISO 6326-5:1997 E Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:34:41 GM
24、T+00:00 2006, Uncontrolled Copy, (c) BSI EN ISO 6326-3:1997 BSI 04-1999 2 Foreword The text of the International Standard from Technical Committee ISO/TC 193, Natural gas, of the International Organization for Standardization (ISO) has been taken over as a European Standard by CEN/CS. This European
25、Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by June 1998, and conflicting national standards shall be withdrawn at the latest by June 1998. According to CEN/CENELEC Internal Regulations, the national standards
26、 organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Licensed Copy:
27、sheffieldun sheffieldun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6326-3:1989 (E) BSI 04-19993 1 Scope This part of ISO 6326 specifies a potentiometric method for the determination of hydrogen sulfide, mercaptan sulfur, and carbonyl sulfide sulfur in natural gas in the
28、concentration range equal to or above 1 mg/m3. The gas must be free of dust, mist, oxygen, hydrogen cyanide and carbon disulfide. The hydrogen sulfide/mercaptan sulfur ratio and also the mercaptan sulfur/hydrogen sulfide ratio should not exceed 50 : 1. The method is not recommended for gases contain
29、ing more than approximately 1,5 % (V/V) carbon dioxide. NOTEIn all parts of ISO 6326, 1 m3 of gas is expressed at normal conditions (0 C; 101,325 kPa). 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO 6
30、326. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of ISO 6326 are encouraged to investigate the possibility of applying the most recent editions of the standards listed below. Members of IEC and ISO
31、 maintain registers of currently valid International Standards. ISO 385-1:1984, Laboratory glassware Burettes Part 1: General requirements. ISO 648:1977, Laboratory glassware One-mark pipettes. ISO 1042:1983, Laboratory glassware One-mark volumetric flasks. 3 Principle Hydrogen sulfide and mercaptan
32、s are absorbed in a 35 % (m/m) aqueous potassium hydroxide solution and carbonyl sulfide in a 5 % (m/m) ethanoholic monoethanolamine solution. The solutions are titrated potentiometrically using silver nitrate solutions with a silver/silver sulfide electrode system to indicate the end point. 4 Reage
33、nts and materials During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Potassium hydroxide, solution. Dissolve 35 g of potassium hydroxide (KOH) in 65 g of water. NOTEIn order to prevent interference by heavy metal ions, 0,
34、5 g of a mixture of polyaminoacetic acids is added for each 50 ml of absorption solution to inactivate the heavy metal ions. The mixture consists of equal parts of the pentasodium salt of diethylenetriamine pentaacetic acid (Na5DTPA); the trisodium salt of N-hydroxyethylenediamine triacetic acid (Na
35、3HEDTA); the sodium salt of N,N-di(2-hydroxyethyl-glycin) (NaDHEG); the tetrasodium salt of ethylenediamine tetraacetic acid (Na4EDTA). 4.2 Monoethanolamine, solution. Dissolve 5 g of monoethanolamine (C2H7ON) in 95 g of ethanol. 4.3 Nitrogen, purity better than 99,95 %, oxygen-free, under pressure.
36、 4.4 Silver nitrate, standard volumetric solution, c(AgNO3) 0,01 mol/l. For the preparation of the silver nitrate solution use boiled distilled water, cooled to 20 C while bubbling with nitrogen (4.3), to remove all traces of oxygen. Dissolve about 1,7 g of silver nitrate in 200 ml of water in the 1
37、 000 ml one-mark volumetric flask (5.6) and make up to the mark with water. Standardize the solution with hydrochloric acid c(HCl) = 0,01 mol/l. 4.5 Ammonium hydroxide solution (A20 C= 0,90 g/ml). 4.6 Electrolyte solution. Mix 1 000 ml of methanol and 25 ml of ammonium hydroxide solution (4.5). 4.7
38、Cotton-wool, for the removal of dust. 5 Apparatus Ordinary laboratory apparatus and 5.1 Test apparatus, (see Figure 1), consisting of three washing bottles (high-speed absorbers of any suitable design), maximum pore diameter 90 4m to 150 4m; 1 washing bottle for the removal of dust, if required; gas
39、 meter, wet design, tolerance 0,1 litre, with thermometer and water manometer. The thermometer shall have a measuring range of 0 C to at least 30 C. The scale intervals shall be not less than 0,5 C. The connections between the three washing bottles shall be glass to glass sealed by fluorelastomer tu
40、bing. NOTEFor low levels of sulfur compounds, butt connections and stop cocks with polytetrafluoroethylene plugs instead of the screw clamps are recommended. 5.2 One-mark pipette, of capacity 10 ml, complying with ISO 648. 5.3 Microburette, of capacity 10ml, complying with ISO 385-1. 5.4 Beaker, of
41、capacity 300 ml. 5.5 Measuring cylinder, of capacity 50 ml. 5.6 One-mark volumetric flask, of capacity 1 000 ml, complying with ISO 1042. Licensed Copy: sheffieldun sheffieldun, na, Sun Nov 19 15:34:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6326-3:1989 (E) 4 BSI 04-1999 5.7 High-resistance v
42、oltmeter, range 1 000 mV, accuracy better than 5 mV. (An automatic titrimeter may be used, providing that it meets the above specification.) 5.8 Silver/silver sulfide measuring electrode NOTEIon-selective silver/silver sulfide crystal membrane electrodes are commercially available and allow faster a
43、nd more precise titration, especially at low sulfur concentrations. If such an electrode is not available, a conventional silver/silver sulfide electrode may be prepared according to the following procedure. Prepare a solution of sodium sulfide and sodium hydroxide by dissolving 1,2 g of sodium sulf
44、ide nonahydrate (Na2S,9H2O) and 40 g of sodium hydroxide in 1 litre of water. Clean the silver metal of the electrode with fine abrasive paper and immerse it in 100 ml of the sodium sulfide/sodium hydroxide solution, stir the solution and add 10 ml of the silver nitrate solution (4.4) over a period
45、of 10 min to 15 min. Remove the electrode from the solution, wash it with water and wipe it lightly with a clean cloth. The coating should last for several weeks. Before use, soak the electrode for at least 5 min in 100 ml of the electrolytic solution (4.6) to which 0,5 ml of silver nitrate solution
46、 (4.4) has been added. Store the electrode in this solution. 5.9 Silver/silver chloride reference electrode. 5.10 Electric stirrer. 6 Sampling On-line sampling is recommended. In the case where indirect sampling is indispensable, use sampling cylinders in accordance with clause 3 of ISO 6326-1:1989.
47、 7 Procedure 7.1 Preliminary operations Assemble the absorbers in series, as shown in Figure 1. Place 50 ml of potassium hydroxide solution (4.1) in the washing bottle (E), and 50 ml of monoethanolamine solution (4.2) in each of the two washing bottles (F). In order to remove the oxygen dissolved in
48、 the absorption solutions, purge the assembly with nitrogen (4.3) for a period of 5 min to 10 min, at a rate of 1 l/min to 2 l/min. Transfer the washing bottles, closed hermetically with screw-clamps (D), to the sampling point and assemble the testing apparatus as shown in Figure 1. If required, con
49、nect an additional washing bottle filled with cotton-wool (4.7) between the sampling cock (B) and the T-piece (C) to intercept any solid particles. 7.2 Absorption (see Figure 1) Flush the sampling line and the T-piece (C) with gas. Open the screw-clamps (D) at the inlet and outlet of the washing bottles (E and F) and record the initial reading of the gas meter (G). The gas is passed through the absorption solutions at a flow rate of 120 l/h 20 l/h. Read the temperature and pressure of the gas and the atmospheric pressu