1、INTERNATIONAL STANDARD ISO 6326-5 First edition 1989-07-01 Natura1 gas - Determination of Sulfur compounds - Part 5 : Lingener combustion method Gaz naturel - Determination des composh soufr 101,325 kPa). 4 Reagents and materials 2 Normative rederences The following Standards contain provisions whic
2、h, through reference in this text, constitute provisions of this part of ISO 6326. 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
3、the most recent editions of the Standards listed below. Members of IEC and ISO main- tain registers of currently valid International Standards. ISO 385-1 : 1984, Laborstory glassware - 5urettes - Part 7 : General requiremen ts. ISO 648 : 1977, Laborstory glassware - he-mark pipettes. ISO 1042 : 1983
4、, Laboratory glassware - One-mark volume tric flasks. ISO 3585 : 1976, Glass plant, Pipeline and fittings - Properties of borosilicate glass 3.3. During the analysis, use only reagents of recognized analytical grade and only distilled water or water sf equivalent purity. 4% Hydrogen Peroxide, IO % (
5、rnlrn) aqueous Solution, Sulfur-free, as absorbing liquid for the Sulfur oxides. 4.2 Activated carbsn, for adsorption of Sulfur impurities from the combustion air. 4.3 Absorbing liquid : 30 % Onln) aqueous Solution of potassium hydroxide, for the purification of the combustion air. 5 Apparatus The s
6、chematic layout of the apparatus is shown in figure 1. Ordinary laboratory apparatus and ISO 6326-5 : 1989 (El Air Figure 1 - Schematic layout of the apparatus Combustion device Pressure-equalizing vessel Capillary flow meter U-tube manometer Dry gas meter with thermometer Condensate separator Vacuu
7、m pump 5.1 Combustion device (AI The combustion device is manufactured of borosilicate glass complying with ISO 3535. lt consists of the Parts shown in figure 2, 5.1.1 Receiver with cooling jacket (see figure 3). 5.1.2 Flame tube (see figure 4) The outer diameter of the flame tube is determined by t
8、he in- side diameter of the receiver with cooling jacket and the annular gap shown in figure 2. 5.1.3 Burner (see figure 5) For the combustion of natura1 gases a universal burner with a needle valve is often preferable. 5.1.4 Intermediate piece (see figure 6) The thermometer shall have a measuring r
9、ange of 0 OC to at least 100 OC. The scale interval shall be not less than 1 OC. 51.5 Reitmeyer attachment (see figure 7). 5.2 Pressure-equaliming vessel (BL 5.3 Capillary flow meter (C), measuring range 10 I/min to 30 I/min. 5.4 U-tube manometer (D), arm length 500 mm. 5.5 Dry gas meter (E) The ran
10、ge of the meter shall be appropriate for the quantity of Sample to be burned and the meter shall have been recently calibrated. The gas meter shall be equipped with a thermometer for the measurement of the gas temperature. The thermometer shall have a measuring range of 0 OC to at least 30 OC. The s
11、cale intervals shall be not less than 0,5 OC. NOTE - The gas meter should be flushed with the gas to be analysed before the combustion, in particular when analysing gases with dif- ferent Sulfur contents, to avoid disturbance by adsorption and desorp- tion phenomena. 5.6 Condensate separator (FL 5.7
12、 Vacuum pump (GI The suction capacity of the vacuum pump shall be at least 25 I/min. lt is recommended that a drying tower with a drying agent be included between the condensate separator (F) and the vacuum pump (G) to protect the oil in the vacuum pump. 2 ISO 6326-5 : Dimensions in millimetres 1989
13、 (E) Tube8x l- Tube 10 x l- 3,2o,z Annular gap II I I II I 1 11 I I Il I I II I I I II I 11 I I Il ll l Ir 1 I I I I I h l ek l I I 11 / I 11 I 11 I 11 Ii 1 JI * /- Centred flame-tube Figure 2 - Combustion vessel ISO 6326-5 : 1989 (E) Dimensions in millimetres Dimensions in millimetres Conical joint
14、-socket 60/46 Spherical joint-cup 29/ 15-, Hose connectionY C 2 f 0 s / iTube54x 1,8 Tube 75 x 2,2 Conical joint- r / Eight holes 2+ir5 - uniformly distributed over the periphery / / r, 1 socket 45/40 socket 45/40 L Conical joint- cone 60146 Conical joint- cone 60146 Tube 40 x 1,6 Tube 40 x 1,6 Tube
15、44x 1,6 LOne-way cock Figure 3 - Receiver with cooling jacket Figure 4 - Flame tube ISO 6326-5 : 1989 (El Dimensions in millimetres 50 Spherical joint-cup- k-4 13112 Three apertures f-q 9,5 k 0,5 Gas jet apertu 0,l + 0,05 . Tube4Oxl Extension displaced rearward by 90 - ,6- 79n-Y Spherical joint-cup-
16、 1 1919 Conical joint-cone / 45/40 Tube 1Ox l- / Figure 5 - Burner Figure 6 - Intermediate piece Dimensions in millimetres iV- Thermometer Spherical joint-ball- 29115 Dimensions in millimetres i- Bent rearward through 90 Conical joint- socket 14/23 A -0 + 00 -8 joint-socket 14/23 Spherical joint-cup
17、 29115 Spherical joint-ball 29/15i Figure 7 - Reitmeyer attachment 5 ISO 6326-5 : 1989 (El 6 Procedure 61 . Preparation for combustion Draw air, which if necessary should be cleaned of Sulfur im- purities with activated carbon (4.2) and/or absorbing liquid (4.31, through the combustion apparatus wit
18、h the aid of the vacuum pump (GI, with a required volumetric flow about 20 I/min. Remove the burner (5.1.3) and pour sufficient hydrogen peroxide Solution (4.1) into the receiver (5.1.1) to rise around the flame tube (5.1.2) to the height of the burner tip throughout the period of combustion. After
19、connection of the cooling water, the combustion apparatus is ready for use. 6.2 Combustion With a preliminary pressure of about 2 kPa on the U-tube manometer (D), ignite the gas at the removed burner. Carefully introduce the burner, with the flame directed downwards, into the flame tube and note the
20、 reading on the gas meter (EI. The air flow and cooling water flow may have to be adjusted. The temperature and pressure of the gas shall be read during the combustion period. The exhaust gas temperature on the ther- mometer shall be kept between 50 OC and 70 OC. As soon as the required quantity of
21、gas, up to 500 litres depending on Sulfur content (sec clause 7) has been burnt, shut off first the gas supply and then the vacuum pump. Drain the absorbing Solution into a beaker (7.1.2.5 or 7.2.2.61, rinse the receiver with water and note the reading on the gas meter (E). 6.3 Determination of gas
22、volume The volume of gas burnt, shown by the d ifference in readings 3n the gas meter, shall be reduced to nor mal conditions : v _ v *n hnb + Pe) n- Pn T where V is the volume of the gas Sample measured in accordance with 6.2 at temperature T (kelvins) and pressure Pamp + pe (kilopascals); Tn is th
23、e thermodynamic temperature, in kelvins, at nor- mal ambient conditions (273,15 K); T is the thermodynamic Sample; tempera ture, in kelvins, of the gas Pn is the pressure, in kilopascals, at normal conditions (101,325 kPa); Pamb is the atmospheric during gas sampling; Pe is the excess pressure, in k
24、i lopascals, the water manom eter during WS sampling. pressure, in kilopascals, measured measured with 7 Analytical determination With a total Sulfur content of more than 0,l mg Sulfur in the ab- sorption Solution, visual titration with an indicator tan be Chosen, whereas for lower contents turbidim
25、etric titration is preferable. 7.1 Determination of Sulfur content by visual titration 7.1.1 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 7.1.1.1 ZPropanol (Isopropyl alcohol). 7.1 .l.2 Barium perchlorate, Stan
26、dard volumetric Solution. Dissolve 1,7 g of barium perchlorate Ba(C10,)21 in 200 ml of water in the 1 000 ml one-mark volumetric flask (7.1.2.11, make up to the mark with the 2-propanol (7.1.1 .l) and adjust to pH 3,5 with perchloric acid. Standardize the Solution against a Standard reference Soluti
27、on of sulfuric acid, c(H+O) = 0,005 mol/l. 1 ml of this Standard volumetric Solution is equivalent to approximately 0,16 mg sf S. 7.1.1.3 Thorinl), 0,2 % (mlm) aqueous indicator solution. Store in a silica glass or polyethylene bottle. 7.1.1.4 Methylene blue, 0,Ol % (mlm) aqueous indicator Solution.
28、 Store in a silica glass or polyethylene bottle. 7.1.2 Apparatus Ordinary laboratory apparatus and 7.1.2.1 One-mark volumetric flask, of capacity 1 000 ml, complying with ISO 1042. 7.1.2.2 One-mark pipette, of capacity 20 ml, complying with ISO 648. 7.1.2.3 Conical flask, wide neck, of capacity 250
29、ml. 7.1.2.4 Burette, of capacity 25 ml, graduated in 0,05 ml, complying with ISO 385-1, or an automatic titrator. 7.1.2.5 Beaker, of capacity 250 ml. 1) Thorin is the registered trade name for disodium-4-(2-arsonophenyl)-azol-3-hydroxynaphthalene-2,7-disuIfonate. 6 ISO 6326-5 : 1989 (El 7.1.3 Proced
30、ure 7.2.1 .l Barium chloride, Standard voiumetric Solution. WARNING - DO not evaporate over a flame. The concentration of the absorption Solution on the hotplate should generally be done in a closed hood. Handle the beaker carefully because of the danger of explosion caused by peroxide formation. We
31、ar safety glasses during this part of the handling. Mix the concentrated absorption Solution with four times its volume of 2-propanol (7.1 .l. 1). Add 6 to 8 drops of Thorin indicator Solution (7.1.1.3), and up to 10 drops of the methylene blue solution (7.1.1.4) to this soiution. The ratio of Thori
32、n indica tor to methylene blue so modified by the Operator as an d when required. lution may be 7.2.1.3 Methanol. Titrate with the barium perchlorate Standard volumetric solu- tion (7.1 .1.2) until the colour changes from yellow to a perma- nent pink, or in the presence of methylene blue, from green
33、 to purple/grey. The Thorin end Point is very difficult to see in some types of light, particularly fluorescent lighting and direct sunlight. Good results tan be obtained by titrating in front of a daylight lamp. The colour Change tan be readily detected photometrically at a wavelength of 520 nm. 7.
34、1.4 Method of calculation VI Cl (SI = vn Dissolve 0,38 g of barium chloride dihydrate (BaClZ,2H,0) in water in the 1 000 ml one-mark volumetric flask (7.2.2.3) and make up to the mark. Standardize the Solution against 2,00 ml of sulfuric acid Solution c(H2S04) = 0,0025 mol/l diluted with about 25 ml
35、 of water, by the method detailed in 7.2.3. Calculate the Sulfur equivalent of the barium chloride Solution in milligrams per millilitre. 1 ml of this Standard volumetric Solution is equivalent to approximately 0,050 mg of S. 7.2.1.2 Coagulant solution. The total Sulfur content in the natura1 gas is
36、 calculated as mass concentration Q(S), in milligrams per cubic metre, using the equation where Cl is the Sulfur equivalen t, in milligrams of S per millilitre, of the barium perchlorate solu tion (7.1.1. 2); Dissolve 20 g of magnesium chloride hexahydrate (MgC12,6HZO) and 3,5 g of ammonium chloride
37、 (NH vn is the tes t (6.3). volume, in cubic metres, of the gas Sample under Round the result to the nearest 0,5 mg/m3. 7.2 Determinat bY turbidimetric i on of titrati Sulfur co 7.2.1 Reagents During the anal ysis, use only rea gents of recognized ana lytical grade a nd only distilled water or water
38、 of equivalent pur ity. 7.2.1.4 Sodium chloride, Solution. Dissolve 100 g of sodium chloride (NaCI) in 1 000 ml of watet-. 7.2.2 Apparatus Ordinary laboratory apparatus and 7.2.2.1 Photometer, preferably a spectrophotometer having an effective band width of about 50 nm and equipped with a blue-sensi
39、tive photocell for use at 450 nm, or alternatively a filter Photometer equipped with a colour filter having a max- imum transmission at approximately 450 nm. 7.2.2.2 Absorption cells, with a thickness of 50 mm and a volume of at least 100 ml. NOTE - The procedure described assumes an absorbance Chan
40、ge of about 0,lO for each 100 pg of Sulfur in 50 ml of Solution measured in a 50 mm cell. Photometers employing cells of lesser thickness will not give the precision of measurement stated in this method. 7.2.2.3 One-mark volumetric flask, of capacity 1 000 ml, complying with ISO 1042. 7.2.2.4 One-ma
41、rk pipettes, of capacities 1 ml, 2 ml, 5 ml, 20 ml and 25 ml, complying with ISO 648. 7.2.2.5 Burette, of capacity 25 ml, graduated in 0,05 ml, complying with ISO 385-1, or an automatic titrator. 7.2.2.6 Beaker, of capacity 250 ml. 7.2.3 Procedure Add 1 ml of the sodium chloride Solution (7.2.1.4) to the ab- sorption Solution (6.2) in the beaker (7.2.2.6). Evaporate on a hotplate until the contents resch a small volume which shall be not less than 1 ml. WARNING - DO not evaporate over a flame (sec 7.1.3.). 7
