1、Designation: D5236 03 (Reapproved 2011)Standard Test Method forDistillation of Heavy Hydrocarbon Mixtures (Vacuum PotstillMethod)1This standard is issued under the fixed designation D5236; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revi
2、sion, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the procedure for distillation ofheavy hydrocarbon mixtures having initial b
3、oiling 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 criteria are speci
4、fied 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 determination ofstandard d
5、istillation 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 attained. This
6、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 D2892. Thistest method can be used for heavy crude
7、 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,1.5.2 Annex A2Practi
8、ce 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 stated in SI units
9、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 appro-priate safety and health practi
10、ces 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:2D941 Test Method For Density And Relative Density (Spe-cific Gravity) Of Liquids By Lipkin Bicapillary Pyc
11、nom-eter3D1217 Test Method for Density and Relative Density (Spe-cific Gravity) of Liquids by Bingham PycnometerD1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative Density (SpecificGravity), or API Gravity of Crude Petroleum and LiquidPetroleum Products by
12、Hydrometer MethodD1480 Test Method for Density and Relative Density (Spe-cific Gravity) of Viscous Materials by Bingham Pycnom-eterD2892 Test Method for Distillation of Crude Petroleum(15-Theoretical Plate Column)D4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for
13、 Automatic Sampling of Petroleum andPetroleum ProductsD5002 Test Method for Density and Relative Density ofCrude Oils by Digital Density Analyzer3. Terminology3.1 Definitions of Terms Specific to This Standard:1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and
14、 Lubricants and is the direct responsibility of SubcommitteeD02.08 on Volatility.Current edition approved Dec. 1, 2011. Published April 2012. Originallyapproved in 1992. Last previous edition approved in 2007 as D523603(2007).DOI: 10.1520/D5236-03R11.2For referenced ASTM standards, visit the ASTM we
15、bsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM
16、 International, 100 Barr Harbor Drive, 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 i
17、s expressedin millilitres per hour 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 product
18、occurs.3.1.3 distillation flask, nthe 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 (
19、or operating pressure), nthepressure 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 t
20、o thecross-sectional area of the neck.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 sp
21、illover point, nthe lowest point in 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
22、 DiscussionIn this test method, it 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
23、 is approximately equal to theboil-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. Recor
24、ds of vapor temperature, operating 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
25、obtained. Distillationyields by volume 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 me
26、thod is one of a number of tests conductedon 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 fr
27、actions to producesamples for analytical 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 d
28、istillates with residue canbe done 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 impor
29、tant that at the time of first use 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 dist
30、illation head (25, 36, 50, and 70 mm), areallowed.4The 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 li
31、ne, a product receiver(s), and a vacuumpumping 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
32、 breaking. The size of the charge 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
33、size of apparatus.6.2.2 Flasks are 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
34、flasks, the bottom shall beslightly 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.4Cooke, Industrial and Engineering C
35、hemistry, Vol 55, 1963, p. 36.D5236 03 (2011)26.3 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 flas
36、k. The external magnetic drive mustbe capable 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
37、 shall be heated by means of a nickelreinforced 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 b
38、y applying automatic heat to thebottom circuit.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 adequa
39、te.6.5 Distilling Head:6.5.1 The head shall 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 sy
40、stemsuch as a glass fabric mantle capable 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 v
41、aportemperature sensor and opposite to the 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
42、theSTILL HEAD DIMENSION CHARTSize A B C D 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
43、mm 102/75 50/30 70 mmFIG. 1 Distillation HeadD5236 03 (2011)3temperature 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 sen
44、sor willthen permit checking of this dimension.6.5.4 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
45、time of less than 60 s as described in Annex A1.6.5.4.1 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 co
46、m-bination with its associated instrument at the time 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 stan
47、dard.Recalibrate when either the sensor or the instrument 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.V
48、erification at least once a month is recommended. 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 illustrat
49、ed in Fig. 4 shall be fitted to theadapter described 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 o
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