DIN 51400-2-2001 Testing of mineral oils and fuels - Determination of sulfur content (total sulfur) - Part 2 Combusting according to Grote-Krekeler acidimetric titration gravimetri.pdf

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1、Ref. No. DIN 51400-2 : 2001-05English price group 07 Sales No. 010703.03DEUTSCHE NORM May 200151400-2Continued on pages 2 to 9. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has t

2、he exclusive right of sale for German Standards (DIN-Normen).Determining the total sulfur content of petroleumproducts by the Grote-Krekeler combustionmethodTranslation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.ICS 75.160.20Prf

3、ung von Minerallen und Brennstoffen Bestimmung desSchwefelgehaltes (Gesamtschwefel) Teil 2: Verbrennung nachGrote-Krekeler; acidimetrische Titration; gravimetrische BestimmungIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma h

4、as been used throughout as the decimal marker.All dimensions are in millimetres.ForewordThis standard has been prepared by Technical Committee Prfung von flssigen Kraftstoffen und Heizlenof the Fachausschuss Minerall- und Brennstoffnormung of the Normenausschuss Materialprfung (Mate-rials Testing St

5、andards Committee).AmendmentsThis standard differs from the February 1978 edition in that it has been revised in form and substance,references have been updated and data on precision have been included.Previous editionsDIN 51768: 1956-03, 1957-11, 1968-03; DIN 51400-2: 1978-02.1 ScopeThis standard s

6、pecifies a method of determining the sulfur content of gaseous, liquid or solid petroleumproducts containing between 0,1 % and 5 % (m/m) of sulfur, but can be extended to contents of between0,1 % and 0,01 % if thorin titration as described in DIN EN 24260 is used instead of the methods describedin s

7、ubclauses 6.1 and 6.2.When igniting products containing additives, it should be borne in mind that combustion-resistant sulfates(e.g. BaSO4) left behind in the ash are not detected in the final analysis and it may therefore be necessaryto determine the sulfur content of the ash separately. Additives

8、 containing phosphorus or halogens or thatyield acid-forming oxides during combustion may also falsify the result. However, nitrogen contents of lessthan 1 % (m/m) have only a slight effect on the analysis. If the sample contains only chlorine in addition tosulfur and no other impurities, the chlori

9、ne content can be determined volumetrically and allowed for incalculating the sulfur content.NOTE: The combustion apparatus described in subclause 5.1.1 may also be used to determine the selenium,halogen and hydrocarbon contents. See 2 and 4 for further information.Supersedes February 1978edition.Pa

10、ge 2DIN 51400-2 : 2001-052 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These norma-tive references are cited at the appropriate places in the text, and the titles of the publications are listed below.For dated references, subsequ

11、ent amendments to or revisions of any of these publications apply to thisstandard only when incorporated in it by amendment or revision. For undated references, the latest edition ofthe publication referred to applies.DIN 12252 Conical ground glass stoppers for laboratory useDIN 12331 Beakers for la

12、boratory useDIN 12332 Low form beakers for laboratory useDIN 12385 Wide neck Erlenmeyer flasks for laboratory useDIN 12480 Woulfe bottles for laboratory useDIN 12541-1 Straight bore stopcocks for laboratory useDIN 12596 Drechsel gas washing bottles for laboratory useDIN 12700-3 Burettes fitted with

13、offset burette stopcock with tail, for laboratory useDIN 12700-5 Automatic zero burettes with reservoir (Pellet burettes)DIN 51400-1 Determination of total sulfur content of mineral oils and fuels General principlesDIN 51400-3 Determining the total sulfur content of petroleum products by the Schnige

14、r combustionmethod and thorin or sulfanazo III titrationDIN 51400-4 Determining the total sulfur content of petroleum products by the Lingener combustionmethodDIN 51610 Sampling of liquefied petroleum gasesDIN EN ISO 4259 Petroleum products Determination and application of precision data in relation

15、 to meth-ods of test (ISO 4259 : 1992 + Corr 1 : 1993)DIN EN ISO 14596 Petroleum products Determination of sulfur content Wavelength-dispersive X-ray fluo-rescence spectrometry (ISO 14596 : 1998)DIN EN 24260 Petroleum products and hydrocarbons Determination of sulfur content Wickbold com-bustion met

16、hod (ISO 4260 : 1987)DIN EN ISO 8754 Petroleum products Determination of sulfur content of petroleum products Energy-dispersive X-ray fluorescence method (ISO 8754 : 1992)3 PrincipleGaseous or vaporized samples are burnt in a stream of air behind a glass filter plate sealed into a combustiontube, pr

17、otection being provided against blowback. The gas produced is sucked through an absorption vesselequipped with a filter plate and containing hydrogen peroxide solution to convert the sulfur oxides into sulfuricacid. The sulfate ions in the absorption solution are then determined volumetrically or gr

18、avimetrically, depend-ing on the type of additives present in the sample.NOTE: Experiments on products containing additives have shown that the percentage by mass of sulfurretained as combustion-resistant sulfate in the ash is always below 0,05 %. Only volatile sulfur is detectedin products that are

19、 fed to the burner after vaporization in the liquid state (e.g. liquefied gas).4 DesignationDesignation of the method of determining the total sulfur content by the Grote-Krekeler combustion methodas specified in this standard (02):Method DIN 51400-02Page 3DIN 51400-2 : 2001-05Key1 Combustion tube 1

20、9 Sheet metal housing2 Screen 10 Gas burner3 Filter plate 11 Gas burner4 Filter plate 12 Combustion boat5 Absorption vessel 13 Washing bottle with glass wool6 Filter plate 14 Washing bottle with KOH solution7 U-tube filled with beads 15 Flowmeter8 StandFigure 1: Grote-Krekeler combustion apparatus5

21、Combustion of sample and analysis of absorption solution5.1 ApparatusThe following equipment shall be used.5.1.1 Grote-Krekeler combustion apparatus (figure 1)5.1.1.1 Combustion tubeTo ensure complete mixing of the burning gases or fumes with the combustion air and to prevent liquid samplecomponents

22、 reaching a filter plate (3), there shall be a clear screen (2) having a central hole 5 mm in diameterapproximately in the centre of the combustion tube (1). Fused into that half of the combustion tube that isconnected to the absorption vessel (5), there shall be two filter plates (3 and 4) spaced 5

23、5 mm apart and havinga maximum pore diameter of 90 m to 150 m. Filter plate (3) prevents the flame burning behind it from blowingback, while filter plate (4) has a catalytic action on the combustion and also retains soot particles produced bypartial combustion.The combustion tube, the screen and the

24、 filter plates shall be made of quartz glass produced by fusing high-purity rock crystal. The filter plates shall not exhibit any peripheral vitrification and shall be uniformly permeable.Although quartz glass tubes used for combustion are sensitive to phosphorus and substances containingphosphorus

25、(e.g. some lubricating oil additives), they can be protected by inserting a quartz glass tube about100 mm long at the point where a combustion boat (12) is introduced.NOTE: Combustion tubes that have gradually become opaque during use can readily be rendered transparentagain by companies that produc

26、e quartz glass products.5.1.1.2 Absorption vesselThe absorption vessel shall be made of chemically resistant glass (in exceptional cases of quartz glass) andfitted with a 4,5 mm thick glass filter plate (6) having a diameter of at least 40 mm and a maximum pore diameterof 15 m to 40 m in its longer

27、limb. The lower half of the bulbous enlargement underneath the filter plate andthe limb of the U-tube joined to it shall be filled with beads (7) made of chemically resistant glass or, possibly,quartz glass and about 6 mm in diameter.Air streamGlass wool Potassium hydroxide solutionPage 4DIN 51400-2

28、 : 2001-05At a gauge pressure of 90 mbar to 120 mbar, the filter plate shall readily allow gas through if it is covered withwater. A DIN 12596 B 250 washing bottle with a pore diameter of 90 m to 150 m may be used instead ofthe absorption vessel.5.1.1.3 Stand and heatersThe combustion tube shall be

29、mounted on a simple stand (8) and be tilted slightly towards the air stream. Thestand also supports a slidable sheet-metal housing (9) that is lined with asbestos and inside which the spaceon either side of filter plate (4) is heated by a gas burner (10) to a temperature of 960 C to 1000 C. A furthe

30、rgas burner (11) is set to a low flame and is used to heat the porcelain combustion boat containing the sample.Two suitable electric furnaces may be used instead of the gas burners.5.1.1.4 Washing bottles and drying towerTwo washing bottles having fritless washing bottle inserts (e.g. type A DIN 125

31、96 washing bottles), one (13)containing glass wool and the other (14) being filled with 30 % (m/m) potassium hydroxide solution, are usedto purify the combustion air, which is drawn in from outside. If the outside air is heavily polluted, it shall firstbe purified with activated carbon.It is also ad

32、visable to insert a drying tower containing blue gel as drying agent between washing bottle (13) andthe combustion tube since entrained, very fine droplets of potassium hydroxide may otherwise damage thetube.5.1.1.5 Vacuum pumpThe combustion air shall be drawn in by a pump having a suction capacity

33、of 200 l/h. If a water-jet pump is used,a non-return valve shall be inserted.A three-neck flask (e.g. a DIN 12480 AS 1000 flask) shall be inserted between the vacuum pump and theabsorption vessel, the tube connected to the central neck having a DIN 12541-EHB2 straight bore stopcock forcontrolling th

34、e combustion air stream.Convenient and rapid regulation of the combustion air stream can also be achieved by inserting a T-piecebetween the vacuum pump and the absorption vessel. Fitted to the free limb by means of a vacuum hose, thereshall be a control valve that controls the combustion air by thro

35、ttling or releasing the secondary air by rotatingthe valve or by placing a finger on the valve opening.5.1.2 Introduction of sample into combustion tube5.1.2.1 Porcelain combustion boat, 50 mm to 70 mm long, for solid and low-volatility samples.5.1.2.2 Sample tube with stopperThe sample tube shall b

36、e made of glass, have an external diameter of 14 mm, a cylindrical part about 90 mmlong and a nominal capacity of about 10 ml, to be used for low-boiling samples. The tube shall be sealed at oneend by drawing it out into a short point and at the other end by means of a natural cork stopper.To preven

37、t it sticking to the combustion tube, the sample tube shall be placed in the latter on a thin-walled claytrough cut by hand from a thin-walled clay tube.5.1.2.3 VaporizerEspecially if the sample sizes are large, samples that volatilize without residue may be fed into the combustiontube from a vapori

38、zer 2 of the bubble-counter type made of high-melting glass or quartz glass. The inlet andoutlet tubes shall be passed through the ground glass stopper and the end of the tapered inlet tube shall beas close as possible to the rounded base of the vaporizer.The purified air drawn in shall be split bet

39、ween washing bottle (13) and the combustion tube into a main streamthat can be controlled by a stopcock and a secondary stream for evaporating the sample. The vaporization canbe increased by throttling the main air stream (see subclauses 5.3.6 and 5.4.1).Samples that volatilize without residue may a

40、lso be measured out using a weighing pipette, but the combustiontube shall then be provided with a beak at about 90 mm from its entrance.5.1.3 Schellbach burette, with automatic zeroing (DIN 12700 MK SKA 10-005 burette).5.1.4 Flowmeter (15), suitable for flow rates between 30 l/h and 300 l/h (e.g. a

41、 rotameter).5.2 ReagentsThe following reagents shall be used.5.2.1 3 % (m/m) acid-free analytical grade hydrogen peroxide solution, H2O2.5.2.2 30 % (m/m) potassium hydroxide solution, KOH.Page 5DIN 51400-2 : 2001-055.3 Preparing the combustion5.3.1 Assemble the combustion apparatus as shown in figur

42、e 1. Transfer 25 ml of hydrogen peroxide in eachcase to the left-hand and right-hand limbs of the absorption vessel. If the washing bottle specified in subclause5.1.1.2 is used instead of the absorption vessel, pour 100 ml of hydrogen peroxide solution into it. Ensure thatthe ground joint between th

43、e combustion tube and absorption vessel is moist so that it can be more easilyuncoupled.5.3.2 Heat the combustion tube on the right and left of filter plate (4) inside the sheet-metal housing to between960 C and 1000 C, and then close the straight bore conical stopcock on the three-neck flask slowly

44、 until anair stream of 150 l/h to 200 l/h is drawn through the washing bottles and through the absorption vessel with thesecondary air shut off (see subclause 5.1.1.5).5.3.3 Bearing in mind the requirements of the volumetric determination (see subclause 6.1), the sample sizeshall be chosen so that t

45、he sample contains between 1 mg and 9 mg of sulfur.5.3.4 For non-readily volatile samples, push the freshly loaded combustion boat into the combustion tubeuntil it is at a distance of 10 mm to 30 mm from the screen.Some substances have a tendency to migrate during combustion so that part of the samp

46、le ends up in frontof the screen in the combustion tube after vaporization. This can be prevented by topping up the freshly loadedcombustion boat with fine sand that has previously been boiled in hydrochloric acid and baked. Vaporizationof the sample discolours the sand and is therefore complete onl

47、y when the sand has recovered its originalcolour.5.3.5 If a sample tube as described in subclause 5.1.2.2 is used for readily volatile sample material, seal thetube after filling with the stopper and, after weighing and immediately before pushing the clay trough into thecombustion tube, break off a

48、piece of the end of the sample tube drawn out into a capillary and place the tubewith the capillary pointing in the direction of the filter plates in the trough with the piece broken off alongsideit. This arranges the tube with its capillary in the uppermost position, thereby preventing the liquid c

49、ontents frombeing suddenly forced out. As the sample tube is gradually heated, the sample first vaporizes through the opencapillary. Towards the end of combustion, i.e. when the heating is more intense, the stopper burns, therebyopening the other end of the tube so that any residues in the tube are able to vaporize or burn completely. Allowfor the sulfur content of the stopper by performing a blank test.5.3.6 If the vaporizer described in subclause 5.1.2.3 is used, heat it after vaporizing all the readily volatileconstituents of the sample,