1、Designation: D 5236 03 (Reapproved 2007)An American National StandardStandard Test Method forDistillation of Heavy Hydrocarbon Mixtures (Vacuum PotstillMethod)1This standard is issued under the fixed designation D 5236; the number immediately following the designation indicates the year oforiginal a
2、doption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure for distillation ofheavy hydro
3、carbon mixtures having initial boiling pointsgreater than 150C (300F), such as heavy crude oils, petro-leum distillates, residues, and synthetic mixtures. It employs apotstill with a low pressure drop entrainment separator oper-ated under total takeoff conditions. Distillation conditions andequipmen
4、t performance criteria are specified and typical appa-ratus is illustrated.1.2 This test method details the procedures for the produc-tion of distillate fractions of standardized quality in the gas oiland lubricating oil range as well as the production of standardresidue. In addition, it provides fo
5、r the determination ofstandard distillation curves to the highest atmospheric equiva-lent temperature possible by conventional distillation.1.3 The maximum achievable atmospheric equivalent tem-perature (AET) is dependent upon the heat tolerance of thecharge. For most samples, a temperature up to 56
6、5C (1050F)can be attained. This maximum will be significantly lower forheat sensitive samples (for example, heavy residues) and mightbe somewhat higher for nonheat sensitive samples.1.4 The recommended distillation method for crude oils upto cutpoint 400C (752F) AET is Test Method D 2892. Thistest m
7、ethod can be used for heavy crude oils with initial boilingpoints greater than 150C (302F). However, distillation curvesand fraction qualities obtained by these methods are notcomparable.1.5 This test method contains the following annexes:1.5.1 Annex A1Test Method for Determination of Tem-perature R
8、esponse Time,1.5.2 Annex A2Practice for Calibration of Sensors,1.5.3 Annex A3Test Method for Dehydration of a WetSample of Oil,1.5.4 Annex A4Practice for Conversion of Observed Va-por Temperature to Atmospheric Equivalent Temperature(AET), and1.5.5 Annex A5Test Method for Determination of Wet-tage.1
9、.6 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appr
10、o-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For specificwarnings, see 6.5.4.2, 6.5.6.3, 6.9.3, 9.5, 9.7, and A2.3.1.3.2. Referenced Documents2.1 ASTM Standards:2D 941 Test Method for Density and Relative Density (Spe-cific Gravity) of
11、 Liquids by Lipkin Bicapillary Pycnom-eter3D 1217 Test Method for Density and Relative Density(Specific Gravity) of Liquids by Bingham PycnometerD 1250 Guide for Use of the Petroleum MeasurementTablesD 1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petroleu
12、m and LiquidPetroleum Products by Hydrometer MethodD 1480 Test Method for Density and Relative Density(Specific Gravity) of Viscous Materials by Bingham Pyc-nometerD 2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)D 4057 Practice for Manual Sampling of Petroleum andP
13、etroleum ProductsD 4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsD 5002 Test Method for Density and Relative Density ofCrude Oils by Digital Density Analyzer1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direc
14、t responsibility of SubcommitteeD02.08 on Volatility.Current edition approved Dec. 1, 2007. Published January 2008. Originallyapproved in 1992. Last previous edition approved in 2003 as D 523603.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at
15、serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3. Terminology3.1 Definitions of Terms S
16、pecific to This Standard:3.1.1 boil-up rate, nthe quantity of vapor entering thedistillation head per unit time.3.1.1.1 DiscussionIt is approximately equal to the takeoffrate, differing only by the parasitic heat losses. It is expressedin millilitres per hour for a head of any given internal diamete
17、ror millilitres per hour per square centimetre of cross-sectionalarea of the throat for comparative purposes.3.1.2 condenser, nthe apparatus connected to the outlet ofthe distillation head in which condensation of the productoccurs.3.1.3 distillation flask, nthe flask, of glass or metal, inwhich the
18、 charge is boiled.3.1.3.1 DiscussionThe flask is sometimes called a kettleor pot.3.1.4 distillation head, nthe section immediately abovethe distillation flask containing the entrainment separator.3.1.5 distillation pressure (or operating pressure), nthepressure measured in the distillation head just
19、 before the outletto the recovery system.3.1.6 distillation temperature (or vapor temperature),nthe temperature of the vapors in the distillation head at thepoint of measurement.3.1.7 loading, nthe volume of charge relative to thecross-sectional area of the neck.3.1.8 pressure drop, nthe difference
20、between the operat-ing pressure and the pressure measured in the distillation flask.3.1.8.1 DiscussionIt is a result of the friction developedby driving the vapors through the system expressed in kilopas-cals (mm Hg).3.1.9 spillover point, nthe lowest point in the head abovethe entrainment separator
21、 over which the vapors can flow to thecondensing region.3.1.10 static hold-up (or wettage), nthe amount of liquidmaterial remaining on the inside of the walls of the apparatusafter the distillation has been completed.3.1.10.1 DiscussionIn this test method, it includes wet-tage of the distillation fl
22、ask in the case of the steel flasks, butnot in the case of glass flasks that are removed for weighingafter the distillation is completed.3.1.11 takeoff rate, nthe quantity of product removed perunit time.3.1.11.1 DiscussionIt is approximately equal to theboil-up rate differing only by parasitic heat
23、 losses.4. Summary of Test Method4.1 A weighed volume of sample is distilled at absolutepressures between 6.6 and 0.013 kPa (50 and 0.1 mm Hg) atspecified distillation rates. Cuts are taken at preselected tem-peratures. Records of vapor temperature, operating pressure,and other variables are made at
24、 intervals, including at eachcutpoint.4.2 The mass of each fraction is obtained. Distillation yieldsby mass are calculated from the mass of each fraction relativeto the total mass recovery.4.3 The density of each fraction is obtained. Distillationyields by volume are calculated from the volume compu
25、ted foreach fraction at 15C (59F) relative to the total recovery.4.4 Distillation curves of temperature versus mass or vol-ume percent, or both, are drawn using the data from 4.2 and4.3.5. Significance and Use5.1 This test method is one of a number of tests conductedon heavy hydrocarbon mixtures to
26、characterize these materialsfor a refiner or a purchaser. It provides an estimate of the yieldsof fractions of various boiling ranges.5.2 The fractions made by this test method can be usedalone or in combination with other fractions to producesamples for analytical studies and quality evaluations.5.
27、3 Residues to be used in the manufacture of asphalt canalso be made but may not always be suitable. The long heatsoaking that occurs in this test method may alter some of theproperties.NOTE 1While the practice of reblending distillates with residue canbe done to produce a lighter residue, it is not
28、recommended because itproduces blends with irregular properties.5.4 Details of cutpoints must be mutually agreed uponbefore the test begins.5.5 This is a complex procedure involving many interactingvariables. It is most important that at the time of first use of anew apparatus, its components be che
29、cked as detailed inAnnexA1 and Annex A2 and that the location of the vapor tempera-ture sensor be verified as detailed in 6.5.3 and Fig. 1.6. Apparatus6.1 Four sizes of apparatus, based upon the internal diam-eter of the distillation head (25, 36, 50, and 70 mm), areallowed.4The apparatus (see Fig.
30、2) consists of a flask withheating mantles, an upper compensator, and a head containingan entrainment separator. Attached to the head are the vaportemperature sensor, a connection for the vacuum gage, acondenser, a rundown line, a product receiver(s), and a vacuumpumping line with pump. The parts ar
31、e connected by vacuum-tight joints to facilitate servicing.6.2 Distillation Flask:6.2.1 The sizes specified for flasks are at least 50 % largerthan the size of the charge to provide space for suppression offoam and for bubble breaking. The size of the charge for eachsize of still is determined from
32、the loading factor. Therecommended loading factor is between 200 and 400 mL ofcharge per square centimetre of cross sectional area in the neckof the head. Table 1 shows the range of charge volume that isrecommended with each size of apparatus.6.2.2 Flasks are made of borosilicate glass except thosel
33、arger than 10 L, which are made of stainless steel for reasonsof safety.6.2.3 The flask is fitted with a thermowell reaching to within6 mm of the bottom and offset from the center to avoid astirring bar. In the case of glass flasks, the bottom shall be4Cooke, Industrial and Engineering Chemistry, Vo
34、l 55, 1963, p. 36.D 5236 03 (2007)2slightly flattened or slightly concave, but not perfectly flat tofacilitate the rotation of the magnetic stirrer. Steel flasks canhave a cooling coil for rapid quenching of the distillation in anemergency. Fig. 3 shows a typical example.6.3 Stirring SystemA magneti
35、cally driven stirring barapproximately 3-mm diameter and 20-mm long shall beprovided for the glass flasks, or 6-mm diameter by 50-mm longfor the steel flasks. The edges shall be rounded to minimizegrinding the wall of the flask. The external magnetic drive mustbe capable of rotating the bar in the f
36、lask when located directlybelow and touching the mantle. The drive can be used tosupport the apparatus above.An adjustable jacking mechanismis recommended for raising and lowering the stirrer.6.4 Heating System:6.4.1 The flask shall be heated by means of a nickelreinforced quartz fabric heating mant
37、le on the lower half sothat boiling rates of up to 150 mL/h per cm2of the crosssectional area of the neck can be maintained. A heat density of0.5 W/cm2is adequate. Usually two or more circuits are usedto improve heat control by applying automatic heat to thebottom circuit.6.4.2 Atemperature sensor s
38、hall be located between the wallof the flask and the mantle for control of the skin temperature.6.4.3 The upper half of the flask shall be covered with amantle to compensate for heat losses. A heat density of 0.2W/cm2is adequate.6.5 Distilling Head:6.5.1 The head shall conform to the details shown i
39、n Fig. 1.It shall be made of borosilicate glass and be totally enclosed ina silvered glass vacuum jacket having a permanent vacuum ofless than 0.0001 kPa (0.00075 mm Hg).6.5.2 The head shall be enclosed in a heat insulating systemsuch as a glass fabric mantle capable of maintaining the outerwall of
40、the glass vacuum jacket at a temperature 5C below theinternal vapor temperature in the head. For this purpose thevacuum jacket shall have a temperature sensor fastened to theouter wall of the jacket at a point level with the vaportemperature sensor and opposite to the outlet arm of the head.6.5.3 Th
41、e head shall be fitted with an adapter to support thevapor temperature sensor so that it is held centered in the neckwith the top of the sensing tip 3 6 1 mm below the spilloverpoint. This dimension can be checked by removing theSTILL HEAD DIMENSION CHARTSize A B C D E F G H I25 mm 85 mm 75 mm 64 mm
42、 47 mm ID 40 mm OD 45 mm 35/25 28/15 35 mm36 mm 90 mm 75 mm 64 mm 68 mm ID 57 mm OD 56 mm 65/40 35/25 35 mm50 mm 110 mm 100 mm 75 mm 94 mm ID 79 mm OD 79 mm 75/50 35/25 45 mm70 mm 140 mm 100 mm 100 mm 131 mm ID 111 mm OD 1011 mm 102/75 50/30 70 mmFIG. 1 Distillation HeadD 5236 03 (2007)3temperature
43、sensor and inserting in its place a copper wirehaving a short right angle bend at the bottom. By feeling for thespillover point, the distance from the top joint of the adaptorcan be found. Laying the wire on the temperature sensor willthen permit checking of this dimension.6.5.4 The vapor temperatur
44、e sensor shall be either a plati-num resistance thermometer, a thermocouple with the junctionhead fused to the lower tip of the well or any other devicewhich meets the requirements in 6.5.4 and 6.5.4.1. It shall havea response time of less than 60 s as described in Annex A1.6.5.4.1 The vapor tempera
45、ture measuring device shall havean accuracy of 0.5C or better and be measured with aresolution of 0.1C or better.6.5.4.2 The vapor temperature measuring device shall becalibrated over the full range of useful temperatures in com-bination with its associated instrument at the time of first useand at
46、least once per year thereafter as described in A2.2.2.Alternatively, certified sensors may be used, provided thecalibration of the sensor and its associated recording instru-ment can be traced back to a primary temperature standard.Recalibrate when either the sensor or the instrument is repairedor s
47、erviced. (WarningVapor temperature measurement isone of the two major sources of error in distillation data.)6.5.4.3 Verification of the calibration of the vapor tempera-ture measuring devices is to be made on a regular basis.Verification at least once a month is recommended. Verificationof the cali
48、bration of the sensors can be accomplished poten-tiometrically by the use of standard precision resistance or bydistilling a pure compound with accurately known boilingpoint, as described in A2.2.3.6.5.5 Ahead trap as illustrated in Fig. 4 shall be fitted to theadapter described in 6.5.3 for connect
49、ion to the vacuum sensor.It shall be kept filled with crushed dry ice at all times while inservice.6.5.6 A vacuum sensor shall be connected to the sidearm ofthe trap. The sensor shall be capable of reading the pressurewith a precision equal to or better than 0.00133 kPa (0.01 mmHg), whichever is greater. A non-tilting McLeod gage canachieve this accuracy when properly used, but a mercurymanometer will permit this accuracy only down to a pressureof about 1 kPa and then only when read with a goodFIG. 2 ApparatusTABLE 1 Standard Charge and Flask
