1、Designation: D5236 18D5236 18aStandard 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
2、 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. Scope*1.1 This test method covers the procedure for distillation of heavy hydrocarbon mixtures having initial boiling
3、points greaterthan 150 C (300 F), such as heavy crude oils, petroleum distillates, residues, and synthetic mixtures. It employs a potstill witha low pressure drop entrainment separator operated under total takeoff conditions. Distillation conditions and equipmentperformance criteria are specified an
4、d typical apparatus is illustrated.1.2 This test method details the procedures for the production of distillate fractions of standardized quality in the gas oil andlubricating oil range as well as the production of standard residue. In addition, it provides for the determination of standarddistillat
5、ion curves to the highest atmospheric equivalent temperature possible by conventional distillation.1.3 The maximum achievable atmospheric equivalent temperature (AET) is dependent upon the heat tolerance of the charge.For most samples, a temperature up to 565 C (1050 F) can be attained. This maximum
6、 will be significantly lower for heatsensitive samples (for example, heavy residues) and might be somewhat higher for nonheat sensitive samples.1.4 The recommended distillation method for crude oils up to cutpoint 400 C (752 F) AET is Test Method D2892. This testmethod can be used for heavy crude oi
7、ls with initial boiling points greater than 150 C (302 F). However, distillation curves andfraction qualities obtained by these methods are not comparable.1.5 This test method contains the following annexes:1.5.1 Annex A1Test Method for Determination of Temperature Response Time,1.5.2 Annex A2Practi
8、ce for Calibration of Sensors,1.5.3 Annex A3Test Method for Dehydration of a Wet Sample of Oil,1.5.4 Annex A4Practice for Conversion of Observed Vapor Temperature to Atmospheric Equivalent Temperature (AET), and1.5.5 Annex A5Test Method for Determination of Wettage.1.6 The values stated in SI units
9、are to be regarded as standard. The values given in parentheses after SI units are provided forinformation only and are not considered standard.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this stand
10、ard to establish appropriate safety, health, and environmental practices and determine the applicability ofregulatory limitations prior to use. For specific warnings, see 6.5.4.2, 6.5.6.3, 6.9.3, 9.5, 9.7, and A2.3.1.3.1.8 WARNINGMercury has been designated by many regulatory agencies as a hazardous
11、 materialsubstance that can causecentral nervous system, kidney, and liver damage. serious medical issues. Mercury, or its vapor, may has been demonstrated to behazardous to health and corrosive to materials. Caution should be taken Use Caution when handling mercury and mercurycontaining mercury-con
12、taining products. See the applicable product Material Safety Data Sheet (MSDS) for details and EPAswebsitehttp:/www.epa.gov/mercury/faq.htmfor additional information. Users should be aware (SDS) for additional informa-tion. The potential exists that selling mercury and/or mercury containing products
13、 into your state or country may be prohibited bylaw.or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in theirlocation.1.9 This international standard was developed in accordance with internationally recognized principles on stand
14、ardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.1 This test method is under the jurisdiction ofASTM Committee D02 on Petroleum Products, Li
15、quid Fuels, and Lubricants and is the direct responsibility of SubcommitteeD02.08 on Volatility.Current edition approved April 1, 2018July 1, 2018. Published April 2018July 2018. Originally approved in 1992. Last previous edition approved in 20172018 as D5236 17. 18. DOI: 10.1520/D5236-18.10.1520/D5
16、236-18A.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult p
17、rior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
18、9428-2959. United States12. Referenced Documents2.1 ASTM Standards:2D941 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Lipkin Bicapillary Pycnometer (Withdrawn1993)3D1217 Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham PycnometerD
19、1250 Guide for Use of the Petroleum Measurement TablesD1298 Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products byHydrometer MethodD1480 Test Method for Density and Relative Density (Specific Gravity) of Viscous Materials by Bingham PycnometerD2
20、892 Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)D4057 Practice for Manual Sampling of Petroleum and Petroleum ProductsD4177 Practice for Automatic Sampling of Petroleum and Petroleum ProductsD5002 Test Method for Density and Relative Density of Crude Oils by Digital
21、Density Analyzer3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 boil-up rate, nthe quantity of vapor entering the distillation head per unit time.3.1.1.1 DiscussionIt is approximately equal to the takeoff rate, differing only by the parasitic heat losses. It is expressed in mi
22、llilitres per hour fora head of any given internal diameter or millilitres per hour per square centimetre of cross-sectional area of the throat forcomparative purposes.3.1.2 condenser, nthe apparatus connected to the outlet of the distillation head in which condensation of the product occurs.3.1.3 d
23、istillation flask, nthe flask, of glass or metal, in which the charge is boiled.3.1.3.1 DiscussionThe flask is sometimes called a kettle or pot.3.1.4 distillation head, nthe section immediately above the distillation flask containing the entrainment separator.3.1.5 distillation pressure (or operatin
24、g pressure), nthe pressure measured in the distillation head just before the outlet to therecovery system.3.1.6 distillation temperature (or vapor temperature), nthe temperature of the vapors in the distillation head at the point ofmeasurement.3.1.7 loading, nthe volume of charge relative to the cro
25、ss-sectional area of the neck.3.1.8 pressure drop, nthe difference between the operating pressure and the pressure measured in the distillation flask.3.1.8.1 DiscussionIt is a result of the friction developed by driving the vapors through the system expressed in kilopascals (mm Hg).3.1.9 spillover p
26、oint, nthe lowest point in the head above the entrainment separator over which the vapors can flow to thecondensing region.3.1.10 static hold-up (or wettage), nthe amount of liquid material remaining on the inside of the walls of the apparatus afterthe distillation has been completed.3.1.10.1 Discus
27、sionIn this test method, it includes wettage of the distillation flask in the case of the steel flasks, but not in the case of glass flasks thatare removed for weighing after the distillation is completed.3.1.11 takeoff rate, nthe quantity of product removed per unit time.2 For referencedASTM standa
28、rds, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 The last approved version of this historical standard is referenced on www.astm.org.D5
29、236 18a23.1.11.1 DiscussionIt is approximately equal to the boil-up rate differing only by parasitic heat losses.4. Summary of Test Method4.1 A weighed volume of sample is distilled at absolute pressures between 6.6 kPa and 0.013 kPa (50 mm Hg and 0.1 mm Hg)at specified distillation rates. Cuts are
30、taken at preselected temperatures. Records of vapor temperature, operating pressure, andother variables are made at intervals, including at each cutpoint.4.2 The mass of each fraction is obtained. Distillation yields by mass are calculated from the mass of each fraction relative tothe total mass rec
31、overy.4.3 The density of each fraction is obtained. Distillation yields by volume are calculated from the volume computed for eachfraction at 15 C (59 F) relative to the total recovery.4.4 Distillation curves of temperature versus mass or volume percent, or both, are drawn using the data from 4.2 an
32、d 4.3.5. Significance and Use5.1 This test method is one of a number of tests conducted on heavy hydrocarbon mixtures to characterize these materials fora refiner or a purchaser. It provides an estimate of the yields of fractions of various boiling ranges.5.2 The fractions made by this test method c
33、an be used alone or in combination with other fractions to produce samples foranalytical studies and quality evaluations.5.3 Residues to be used in the manufacture of asphalt can also be made but may not always be suitable. The long heat soakingthat occurs in this test method may alter some of the p
34、roperties.NOTE 1While the practice of reblending distillates with residue can be done to produce a lighter residue, it is not recommended because it producesblends with irregular properties.5.4 Details of cutpoints must be mutually agreed upon before the test begins.5.5 This is a complex procedure i
35、nvolving many interacting variables. It is most important that at the time of first use of a newapparatus, its components be checked as detailed in AnnexA1 and AnnexA2 and that the location of the vapor temperature sensorbe verified as detailed in 6.5.3 and Fig. 1.6. Apparatus6.1 Four sizes of appar
36、atus, based upon the internal diameter of the distillation head (25 mm, 36 mm, 50 mm, and 70 mm), areallowed.4 The apparatus (see Fig. 2) consists of a flask with heating mantles, an upper compensator, and a head containing anentrainment separator. Attached to the head are the vapor temperature sens
37、or, a connection for the vacuum gauge, a condenser, arundown line, a product receiver(s), and a vacuum pumping line with pump. The parts are connected by vacuum-tight joints tofacilitate servicing.6.2 Distillation Flask:6.2.1 The sizes specified for flasks are at least 50 % larger than the size of t
38、he charge to provide space for suppression of foamand for bubble breaking. The size of the charge for each size of still is determined from the loading factor. The recommendedloading factor is between 200 mLand 400 mLof charge per square centimetre of cross-sectional area in the neck of the head. Ta
39、ble1 shows the range of charge volume that is recommended with each size of apparatus.6.2.2 Flasks are made of borosilicate glass except those larger than 10 L, which are made of stainless steel for reasons of safety.6.2.3 The flask is fitted with a thermowell reaching to within 6 mm of the bottom a
40、nd offset from the center to avoid a stirringbar. In the case of glass flasks, the bottom shall be slightly flattened or slightly concave, but not perfectly flat to facilitate therotation of the magnetic stirrer. Steel flasks can have a cooling coil for rapid quenching of the distillation in an emer
41、gency. Fig.3 shows a typical example.6.3 Stirring SystemAmagnetically driven stirring bar approximately 3 mm diameter and 20 mm long shall be provided for theglass flasks, or 6 mm diameter by 50 mm long for the steel flasks. The edges shall be rounded to minimize grinding the wall ofthe flask. The e
42、xternal magnetic drive must be capable of rotating the bar in the flask when located directly below and touchingthe mantle. The drive can be used to support the apparatus above. An adjustable jacking mechanism is recommended for raisingand lowering the stirrer.6.4 Heating System:6.4.1 The flask shal
43、l be heated by means of a nickel-reinforced quartz fabric heating mantle on the lower half so that boilingrates of up to 150 mL/h per cm2 of the cross-sectional area of the neck can be maintained.Aheat density of 0.5 W/cm2 is adequate.Usually two or more circuits are used to improve heat control by
44、applying automatic heat to the bottom circuit.4 Cooke, Industrial and Engineering Chemistry, Vol 55, 1963, p. 36.D5236 18a36.4.2 A temperature sensor shall be located between the wall of the flask and the mantle for control of the skin temperature.6.4.3 The upper half of the flask shall be covered w
45、ith a mantle to compensate for heat losses. A heat density of 0.2 Wcm2 isadequate.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 in asilvered glass vacuum jacket having a permanent vacuum of less than 0.
46、0001 kPa (0.00075 mm Hg).6.5.2 The head shall be enclosed in a heat-insulating system such as a glass fabric mantle capable of maintaining the outer wallof the glass vacuum jacket at a temperature 5 C below the internal vapor temperature in the head. For this purpose, the vacuumjacket shall have a t
47、emperature sensor fastened to the outer wall of the jacket at a point level with the vapor temperature sensorand opposite to the outlet arm of the head.6.5.3 The head shall be fitted with an adapter to support the vapor temperature sensor so that it is held centered in the neck withthe top of the se
48、nsing tip 3 mm 6 1 mm below the spillover point. This dimension can be checked by removing the temperaturesensor and inserting in its place a copper wire having a short right angle bend at the bottom. By feeling for the spillover point,the distance from the top joint of the adaptor can be found. Lay
49、ing the wire on the temperature sensor will then permit checkingof this dimension.6.5.4 The vapor temperature sensor shall be either a platinum resistance thermometer, a thermocouple with the junction headfused to the lower tip of the well, or any other device which meets the requirements in 6.5.4 and 6.5.4.1. It shall have a responsetime of less than 60 s as described in Annex A1.6.5.4.1 The vapor temperature measuring device shall have an accuracy of 0.5 C or better and be measured with a resolutionof 0.1 C or better.STILL HEAD DIMENSI
