1、Designation: D5236 18Standard 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 revision, the year of
2、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. Scope*1.1 This test method covers the procedure for distillation ofheavy hydrocarbon mixtures having initial boiling pointsgrea
3、ter than 150 C (300 F), such as heavy crude oils,petroleum distillates, residues, and synthetic mixtures. It em-ploys a potstill with a low pressure drop entrainment separatoroperated under total takeoff conditions. Distillation conditionsand equipment performance criteria are specified and typicala
4、pparatus 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 distillation curves
5、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 565 C(1050 F) can be attained. This maximum will be s
6、ignificantlylower for heat sensitive samples (for example, heavy residues)and might be somewhat higher for nonheat sensitive samples.1.4 The recommended distillation method for crude oils upto cutpoint 400 C (752 F) AET is Test Method D2892. Thistest method can be used for heavy crude oils with init
7、ial boilingpoints greater than 150 C (302 F). However, distillationcurves and 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 A2Practice for Calibr
8、ation 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 are to be reg
9、arded asstandard. The values given in parentheses after SI units areprovided for information only and are not considered standard.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 establis
10、h appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific warnings, see 6.5.4.2, 6.5.6.3, 6.9.3, 9.5, 9.7, andA2.3.1.3.1.8 WARNINGMercury has been designated by manyregulatory agencies as a hazardous material that
11、can causecentral nervous system, kidney, and liver damage. Mercury, orits vapor, may be hazardous to health and corrosive tomaterials. Caution should be taken when handling mercury andmercury containing products. See the applicable product Ma-terial Safety Data Sheet (MSDS) for details and EPAswebsi
12、tehttp:/www.epa.gov/mercury/faq.htmfor addi-tional information. Users should be aware that selling mercuryand/or mercury containing products into your state or countrymay be prohibited by law.1.9 This international standard was developed in accor-dance with internationally recognized principles on s
13、tandard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:21This test method is under the jurisdictio
14、n of ASTM Committee D02 onPetroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility ofSubcommittee D02.08 on Volatility.Current edition approved April 1, 2018. Published April 2018. Originallyapproved in 1992. Last previous edition approved in 2017 as D5236 17. DOI:10.1520/D5
15、236-18.2For referenced ASTM standards, visit the ASTM website, 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.*A Summary of Changes section appears at the end of th
16、is standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopme
17、nt of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1D941 Test Method for Density and Relative Density (Spe-cific Gravity) of Liquids by Lipkin Bicapillary Pycnom-eter (Withdrawn 1993)3D1217 Test Method for Dens
18、ity 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, or APIGravity of Crude Petroleum and Liquid Petroleum Prod-ucts by Hydrometer MethodD1480 Test Method for Density and R
19、elative 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 Automatic Sampling of Petroleum andPetroleum Produc
20、tsD5002 Test Method for Density and Relative Density ofCrude Oils by Digital Density Analyzer3. Terminology3.1 Definitions of Terms Specific 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 take
21、offrate, differing only by the parasitic heat losses. It is 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 of
22、the distillation head in which condensation of the productoccurs.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 containi
23、ng the entrainment separator.3.1.5 distillation pressure (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 m
24、easurement.3.1.7 loading, nthe volume of charge relative to thecross-sectional area of the neck.3.1.8 pressure drop, nthe difference between the operatingpressure and the pressure measured in the distillation flask.3.1.8.1 DiscussionIt is a result of the friction developedby driving the vapors throu
25、gh the system expressed in kilopas-cals (mm Hg).3.1.9 spillover 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 app
26、aratusafter the distillation has been completed.3.1.10.1 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 quanti
27、ty of product removed perunit time.3.1.11.1 DiscussionIt 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 kPa and 0.013 kPa (50 mm Hg and0.1 mm Hg) at specified dist
28、illation rates. Cuts are taken atpreselected temperatures. Records of vapor temperature, oper-ating pressure, and other variables are made at intervals,including at each cutpoint.4.2 The mass of each fraction is obtained. Distillation yieldsby mass are calculated from the mass of each fraction relat
29、iveto the total mass recovery.4.3 The density of each fraction is obtained. Distillationyields by volume are calculated from the volume computed foreach fraction at 15 C (59 F) relative to the total recovery.4.4 Distillation curves of temperature versus mass or vol-ume percent, or both, are drawn us
30、ing 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 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
31、by this test method can be usedalone or in combination with other fractions 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
32、alter some of theproperties.NOTE 1While the practice of reblending distillates with residue can bedone 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 com
33、plex procedure involving many interactingvariables. It is most important that at the time of first use of anew apparatus, its components be checked as detailed in AnnexA1 and Annex A2 and that the location of the vapor tempera-ture sensor be verified as detailed in 6.5.3 and Fig. 1.3The last approve
34、d version of this historical standard is referenced onwww.astm.org.D5236 1826. Apparatus6.1 Four sizes of apparatus, based upon the internal diam-eter of the distillation head (25 mm, 36 mm, 50 mm, and70 mm), are allowed.4The apparatus (see Fig. 2) consists of aflask with heating mantles, an upper c
35、ompensator, and a headcontaining an entrainment separator. Attached to the head arethe vapor temperature sensor, a connection for the vacuumgauge, a condenser, a rundown line, a product receiver(s), anda vacuum pumping line with pump. The parts are connected byvacuum-tight joints to facilitate servi
36、cing.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 the loading factor. Therecommended loading factor is b
37、etween 200 mL and 400 mLof charge per square centimetre of cross-sectional area in theneck of the head. Table 1 shows the range of charge volumethat is recommended with each size of apparatus.6.2.2 Flasks are made of borosilicate glass except thoselarger than 10 L, which are made of stainless steel
38、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 beslightly flattened or slightly concave, but not perfectly flat tofacilitate the rotation of the mag
39、netic 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 magnetically driven stirring barapproximately 3 mm diameter and 20 mm long shall be pro-vided for the glass flasks, or 6 mm diameter by 50 mm
40、 long forthe 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 flask when located directlybelow and touching the mantle. The drive can be used to4Cooke, Industrial and Engineering Chemistry, Vol 5
41、5, 1963, p. 36.STILL 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
42、 mm OD 1011 mm 102/75 50/30 70 mmFIG. 1 Distillation HeadD5236 183support 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 nickel-reinforced quartz fabric heating mantle on the lowe
43、r half sothat boiling rates of up to 150 mL/h per cm2of the cross-sectional 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 shall be locat
44、ed 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 of0.2 Wcm2is adequate.6.5 Distilling Head:6.5.1 The head shall conform to the details shown in Fig. 1.It sh
45、all 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 the glass vacu
46、um jacket at a temperature 5 C 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 The head shall
47、 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 mm 6 1 mm below thespillover point. This dimension can be checked by removingthe temperature sensor and inserting in its place a copper wirehaving a short right
48、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 temperature sensor shall be either a plati-num resistance thermometer, a therm
49、ocouple with the junctionhead fused to the lower tip of the well, or any other deviceFIG. 2 ApparatusTABLE 1 Standard Charge and Flask SizeInsideDiameter, mmThroatCross-SectionalArea, cm2Charge, L Flask, L25 5 12 2336 10 24 3650 20 48 61270 40 816 1224D5236 184which 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 temperature measuring device shall havean accuracy of 0.5 C or better and be measured with aresolution of 0.1 C or better.6.5.4.2
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