1、Designation: D 5236 03An 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 adoption or, in the
2、 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. Scope*1.1 This test method covers the procedure for distillation ofheavy hydrocarbon mixtures h
3、aving 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 andequipment performance cri
4、teria 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 for the determinati
5、on 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 565C (1050F)can be
6、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 method can be used
7、 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 Response Time,1.5.
8、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.1.6 The values sta
9、ted in SI units are to be regarded as thestandard. The inch-pound units given in parentheses areprovided for information purposes only.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 est
10、ablish appro-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:D 941 Test Method for Density and Relative Density (Spe-cific G
11、ravity) of Liquids by Lipkin Bicapillary Pycnom-eter2D 1217 Test Method for Density and Relative Density(Specific Gravity) of Liquids by Bingham Pycnometer3D 1250 Guide for Petroleum Measurement Tables3,4D 1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petr
12、oleum and LiquidPetroleum Products by Hydrometer Method3D 1480 Test Method for Density and Relative Density(Specific Gravity) of Viscous Materials by Bingham Pyc-nometer3D 2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)3D 4057 Practice for Manual Sampling of Petrole
13、um andPetroleum Products5D 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products5D 5002 Test Method for Density and Relative Density ofCrude Oils by Digital Density Analyzer53. Terminology3.1 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction
14、 of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.08 on Volatility.Current edition approved June 10, 2003. Published August 2003. Originallyapproved in 1992. Last previous edition approved in 2002 as D 523602.2Discontinued. See 1993 Annual
15、 Book of ASTM Standards , Vol 05.01.3Annual Book of ASTM Standards, Vol 05.01.4Description only. Tables are published separately in 12 volumes.5Annual Book of ASTM Standards, Vol 05.02.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Dr
16、ive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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
17、 for a head of any given internal diameteror 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, n
18、the flask, of glass or metal, inwhich the 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), nthepressu
19、re measured in the distillation head just 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 n
20、eck.3.1.8 pressure drop, nthe difference 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 i
21、n the head abovethe entrainment separator 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
22、 includes wet-tage of the distillation flask 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
23、-up rate differing only by parasitic heat 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
24、 pressure,and other variables are made at 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 vo
25、lume are calculated from the volume computed 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 c
26、onductedon heavy hydrocarbon mixtures to 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 anal
27、ytical studies and quality evaluations.5.3 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
28、 to produce a lighter residue, it is not 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
29、 of anew apparatus, its components be checked 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
30、mm), areallowed.6The apparatus (see Fig. 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 v
31、acuumpumping line with pump. The parts are 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
32、for eachsize of still is determined from 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
33、 made of borosilicate glass except thoselarger 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 beslightl
34、y 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.6Cooke, Industrial and Engineering Chemistry, Vol 55, 1963, p. 36.D523
35、60326.3 Stirring SystemA magnetically 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 capa
36、ble of rotating the bar in the flask 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 nickelreinf
37、orced quartz fabric heating mantle 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 cir
38、cuit.6.4.2 Atemperature sensor shall 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 shal
39、l conform to the details shown in 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
40、of maintaining the outerwall of 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
41、 outlet arm of the head.6.5.3 The 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
42、E F G H I25 mm 85 mm 75 mm 64 mm 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 H
43、eadD5236033temperature 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
44、.4 The vapor temperature 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.
45、5.4.1 The vapor temperature 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 t
46、ime of first useand at 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 ins
47、trument is repairedor serviced. (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.
48、Verificationof the calibration 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 describ
49、ed in 6.5.3 for connection 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 Standa
