ASTM D5236-03(2011)
(Test Method)Standard Test Method for Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method)
Standard Test Method for Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill Method)
SIGNIFICANCE AND USE
This test method is one of a number of tests conducted on heavy hydrocarbon mixtures to characterize these materials for a refiner or a purchaser. It provides an estimate of the yields of fractions of various boiling ranges.
The fractions made by this test method can be used alone or in combination with other fractions to produce samples for analytical studies and quality evaluations.
Residues to be used in the manufacture of asphalt can also be made but may not always be suitable. The long heat soaking that occurs in this test method may alter some of the properties.
Note 1—While the practice of reblending distillates with residue can be done to produce a lighter residue, it is not recommended because it produces blends with irregular properties.
Details of cutpoints must be mutually agreed upon before the test begins.
This is a complex procedure involving many interacting variables. It is most important that at the time of first use of a new apparatus, its components be checked as detailed in Annex A1 and Annex A2 and that the location of the vapor temperature sensor be verified as detailed in 6.5.3 and Fig. 1.
STILL HEAD DIMENSION CHART
Size AB CD EF GH I 25 mm 85 mm 75 mm 64 mm 47 mm ID 40 mm OD 4–5 mm 35/2528/1535 mm 36 mm 90 mm 75 mm 64 mm 68 mm ID 57 mm OD 5–6 mm 65/4035/2535 mm 50 mm 110 mm100 mm 75 mm 94 mm ID 79 mm OD 7–9 mm 75/5035/2545 mm 70 mm 140 mm100 mm100 mm131 mm ID111 mm OD10–11 mm102/7550/3070 mmFIG. 1 Distillation Head
SCOPE
1.1 This test method covers the procedure for distillation of heavy hydrocarbon mixtures having initial boiling points greater than 150°C (300°F), such as heavy crude oils, petroleum distillates, residues, and synthetic mixtures. It employs a potstill with a low pressure drop entrainment separator operated under total takeoff conditions. Distillation conditions and equipment performance criteria are specified and 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 and lubricating oil range as well as the production of standard residue. In addition, it provides for the determination of standard distillation 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 will be significantly lower 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 up to cutpoint 400°C (752°F) AET is Test Method D2892. This test method can be used for heavy crude oils with initial boiling points greater than 150°C (302°F). However, distillation curves and fraction qualities obtained by these methods are not comparable.
1.5 This test method contains the following annexes:
1.5.1 Annex A1—Test Method for Determination of Temperature Response Time,
1.5.2 Annex A2—Practice for Calibration of Sensors,
1.5.3 Annex A3—Test Method for Dehydration of a Wet Sample of Oil,
1.5.4 Annex A4—Practice for Conversion of Observed Vapor Temperature to Atmospheric Equivalent Temperature (AET), and
1.5.5 Annex A5—Test Method for Determination of Wettage.
1.6 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine 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, and A2.3.1.3.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5236 − 03(Reapproved 2011)
Standard Test Method for
Distillation of Heavy Hydrocarbon Mixtures (Vacuum Potstill
Method)
This standard is issued under the fixed designation D5236; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5.4 Annex A4—Practice for Conversion of Observed Va-
por Temperature to Atmospheric Equivalent Temperature
1.1 This test method covers the procedure for distillation of
(AET), and
heavy hydrocarbon mixtures having initial boiling points
1.5.5 Annex A5—Test Method for Determination of Wet-
greater than 150°C (300°F), such as heavy crude oils, petro-
tage.
leum distillates, residues, and synthetic mixtures. It employs a
1.6 The values stated in SI units are to be regarded as the
potstill with a low pressure drop entrainment separator oper-
standard. The values given in parentheses are for information
ated under total takeoff conditions. Distillation conditions and
only.
equipment performance criteria are specified and typical appa-
ratus is illustrated.
1.7 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.2 This test method details the procedures for the produc-
responsibility of the user of this standard to establish appro-
tion of distillate fractions of standardized quality in the gas oil
priate safety and health practices and determine the applica-
and lubricating oil range as well as the production of standard
bility of regulatory limitations prior to use. For specific
residue. In addition, it provides for the determination of
warnings, see 6.5.4.2, 6.5.6.3, 6.9.3, 9.5, 9.7, and A2.3.1.3.
standard distillation curves to the highest atmospheric equiva-
lent temperature possible by conventional distillation.
2. Referenced Documents
1.3 The maximum achievable atmospheric equivalent tem-
2.1 ASTM Standards:
perature (AET) is dependent upon the heat tolerance of the
D941Test Method for Density and Relative Density (Spe-
charge.Formostsamples,atemperatureupto565°C(1050°F)
cific Gravity) of Liquids by Lipkin Bicapillary Pycnom-
can be attained. This maximum will be significantly lower for
eter (Withdrawn 1993)
heatsensitivesamples(forexample,heavyresidues)andmight
D1217Test Method for Density and Relative Density (Spe-
be somewhat higher for nonheat sensitive samples.
cific Gravity) of Liquids by Bingham Pycnometer
1.4 The recommended distillation method for crude oils up
D1250Guide for Use of the Petroleum MeasurementTables
to cutpoint 400°C (752°F) AET is Test Method D2892. This
D1298Test Method for Density, Relative Density (Specific
testmethodcanbeusedforheavycrudeoilswithinitialboiling
Gravity), or API Gravity of Crude Petroleum and Liquid
pointsgreaterthan150°C(302°F).However,distillationcurves
Petroleum Products by Hydrometer Method
and fraction qualities obtained by these methods are not
D1480Test Method for Density and Relative Density (Spe-
comparable.
cific Gravity) of Viscous Materials by Bingham Pycnom-
eter
1.5 This test method contains the following annexes:
D2892Test Method for Distillation of Crude Petroleum
1.5.1 Annex A1—Test Method for Determination of Tem-
(15-Theoretical Plate Column)
perature Response Time,
D4057Practice for Manual Sampling of Petroleum and
1.5.2 Annex A2—Practice for Calibration of Sensors,
Petroleum Products
1.5.3 Annex A3—Test Method for Dehydration of a Wet
D4177Practice for Automatic Sampling of Petroleum and
Sample of Oil,
Petroleum Products
1 2
This test method is under the jurisdiction of ASTM Committee D02 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
PetroleumProductsandLubricantsandisthedirectresponsibilityofSubcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
D02.08 on Volatility. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Dec. 1, 2011. Published April 2012. Originally the ASTM website.
approved in 1992. Last previous edition approved in 2007 as D5236–03(2007). The last approved version of this historical standard is referenced on
DOI: 10.1520/D5236-03R11. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5236 − 03 (2011)
D5002Test Method for Density and Relative Density of 4.2 Themassofeachfractionisobtained.Distillationyields
Crude Oils by Digital Density Analyzer by mass are calculated from the mass of each fraction relative
to the total mass recovery.
3. Terminology
4.3 The density of each fraction is obtained. Distillation
3.1 Definitions of Terms Specific to This Standard:
yieldsbyvolumearecalculatedfromthevolumecomputedfor
3.1.1 boil-up rate, n—the quantity of vapor entering the
each fraction at 15°C (59°F) relative to the total recovery.
distillation head per unit time.
4.4 Distillation curves of temperature versus mass or vol-
3.1.1.1 Discussion—It is approximately equal to the takeoff
ume percent, or both, are drawn using the data from 4.2 and
rate, differing only by the parasitic heat losses. It is expressed
4.3.
in millilitres per hour for a head of any given internal diameter
or millilitres per hour per square centimetre of cross-sectional
5. Significance and Use
area of the throat for comparative purposes.
5.1 This test method is one of a number of tests conducted
3.1.2 condenser, n—the apparatus connected to the outlet of
on heavy hydrocarbon mixtures to characterize these materials
the distillation head in which condensation of the product
forarefinerorapurchaser.Itprovidesanestimateoftheyields
occurs.
of fractions of various boiling ranges.
3.1.3 distillation flask, n—the flask, of glass or metal, in
5.2 The fractions made by this test method can be used
which the charge is boiled.
alone or in combination with other fractions to produce
3.1.3.1 Discussion—The flask is sometimes called a kettle
samples for analytical studies and quality evaluations.
or pot.
5.3 Residues to be used in the manufacture of asphalt can
3.1.4 distillation head, n—the section immediately above
the distillation flask containing the entrainment separator. also be made but may not always be suitable. The long heat
soaking that occurs in this test method may alter some of the
3.1.5 distillation pressure (or operating pressure), n—the
properties.
pressure measured in the distillation head just before the outlet
to the recovery system.
NOTE1—Whilethepracticeofreblendingdistillateswithresiduecanbe
done to produce a lighter residue, it is not recommended because it
3.1.6 distillation temperature (or vapor temperature),
produces blends with irregular properties.
n—the temperature of the vapors in the distillation head at the
5.4 Details of cutpoints must be mutually agreed upon
point of measurement.
before the test begins.
3.1.7 loading, n—the volume of charge relative to the
5.5 This is a complex procedure involving many interacting
cross-sectional area of the neck.
variables. It is most important that at the time of first use of a
3.1.8 pressure drop, n—thedifferencebetweentheoperating
newapparatus,itscomponentsbecheckedasdetailedinAnnex
pressure and the pressure measured in the distillation flask.
A1 and AnnexA2 and that the location of the vapor tempera-
3.1.8.1 Discussion—It is a result of the friction developed
ture sensor be verified as detailed in 6.5.3 and Fig. 1.
by driving the vapors through the system expressed in kilopas-
cals (mm Hg).
6. Apparatus
3.1.9 spillover point, n—the lowest point in the head above
6.1 Four sizes of apparatus, based upon the internal diam-
theentrainmentseparatoroverwhichthevaporscanflowtothe
eter of the distillation head (25, 36, 50, and 70 mm), are
condensing region.
allowed. The apparatus (see Fig. 2) consists of a flask with
3.1.10 static hold-up (or wettage), n—the amount of liquid
heating mantles, an upper compensator, and a head containing
material remaining on the inside of the walls of the apparatus
an entrainment separator. Attached to the head are the vapor
after the distillation has been completed.
temperature sensor, a connection for the vacuum gage, a
3.1.10.1 Discussion—In this test method, it includes wet-
condenser,arundownline,aproductreceiver(s),andavacuum
tage of the distillation flask in the case of the steel flasks, but
pumping line with pump. The parts are connected by vacuum-
not in the case of glass flasks that are removed for weighing
tight joints to facilitate servicing.
after the distillation is completed.
6.2 Distillation Flask:
3.1.11 takeoff rate, n—the quantity of product removed per
6.2.1 The sizes specified for flasks are at least 50% larger
unit time.
than the size of the charge to provide space for suppression of
3.1.11.1 Discussion—It is approximately equal to the
foam and for bubble breaking. The size of the charge for each
boil-up rate differing only by parasitic heat losses.
size of still is determined from the loading factor. The
4. Summary of Test Method recommended loading factor is between 200 and 400 mL of
chargepersquarecentimetreofcrosssectionalareaintheneck
4.1 A weighed volume of sample is distilled at absolute
of the head. Table 1 shows the range of charge volume that is
pressures between 6.6 and 0.013 kPa (50 and 0.1 mm Hg) at
recommended with each size of apparatus.
specified distillation rates. Cuts are taken at preselected tem-
peratures. Records of vapor temperature, operating pressure,
and other variables are made at intervals, including at each
cutpoint. Cooke, Industrial and Engineering Chemistry, Vol 55, 1963, p. 36.
D5236 − 03 (2011)
STILL HEAD DIMENSION CHART
Size A B C D E F G H I
25 mm 85 mm 75 mm 64 mm 47 mm ID 40 mm OD 4–5 mm 35/25 28/15 35 mm
36 mm 90 mm 75 mm 64 mm 68 mm ID 57 mm OD 5–6 mm 65/40 35/25 35 mm
50 mm 110 mm 100 mm 75 mm 94 mm ID 79 mm OD 7–9 mm 75/50 35/25 45 mm
70 mm 140 mm 100 mm 100 mm 131 mm ID 111 mm OD 10–11 mm 102/75 50/30 70 mm
FIG. 1 Distillation Head
6.2.2 Flasks are made of borosilicate glass except those 6.4.1 The flask shall be heated by means of a nickel
larger than 10 L, which are made of stainless steel for reasons reinforced quartz fabric heating mantle on the lower half so
of safety. that boiling rates of up to 150 mL/h per cm of the cross
6.2.3 Theflaskisfittedwithathermowellreachingtowithin sectional area of the neck can be maintained.Aheat density of
6 mm of the bottom and offset from the center to avoid a 0.5 W/cm is adequate. Usually two or more circuits are used
stirring bar. In the case of glass flasks, the bottom shall be to improve heat control by applying automatic heat to the
slightly flattened or slightly concave, but not perfectly flat to bottom circuit.
facilitate the rotation of the magnetic stirrer. Steel flasks can
6.4.2 Atemperaturesensorshallbelocatedbetweenthewall
have a cooling coil for rapid quenching of the distillation in an
of the flask and the mantle for control of the skin temperature.
emergency. Fig. 3 shows a typical example.
6.4.3 The upper half of the flask shall be covered with a
mantle to compensate for heat losses. A heat density of 0.2
6.3 Stirring System—A magnetically driven stirring bar
W/cm is adequate.
approximately 3-mm diameter and 20-mm long shall be
providedfortheglassflasks,or6-mmdiameterby50-mmlong
6.5 Distilling Head:
for the steel flasks. The edges shall be rounded to minimize
6.5.1 The head shall conform to the details shown in Fig. 1.
grindingthewalloftheflask.Theexternalmagneticdrivemust
It shall be made of borosilicate glass and be totally enclosed in
becapableofrotatingthebarintheflaskwhenlocateddirectly
a silvered glass vacuum jacket having a permanent vacuum of
below and touching the mantle. The drive can be used to
less than 0.0001 kPa (0.00075 mm Hg).
supporttheapparatusabove.Anadjustablejackingmechanism
6.5.2 The head shall be enclosed in a heat insulating system
is recommended for raising and lowering the stirrer.
such as a glass fabric mantle capable of maintaining the outer
6.4 Heating System: walloftheglassvacuumjacketatatemperature5°Cbelowthe
D5236 − 03 (2011)
FIG. 2 Apparatus
TABLE 1 Standard Charge and Flask Size
6.5.4 The vapor temperature sensor shall be either a plati-
Throat num resistance thermometer, a thermocouple with the junction
Inside
Cross-Sectional Charge, L Flask, L
head fused to the lower tip of the well or any other device
Diameter, mm
Area, cm
whichmeetstherequirementsin6.5.4and6.5.4.1.Itshallhave
25 5 1–2 2–3
a response time of less than 60 s as described in Annex A1.
36 10 2–4 3–6
50 20 4–8 6–12
6.5.4.1 The vapor temperature measuring device shall have
70 40 8–16 12–24
an accuracy of 0.5°C or better and be measured with a
resolution of 0.1°C or better.
6.5.4.2 The vapor temperature measuring device shall be
internal vapor temperature in the head. For this purpose the
calibrated over the full range of useful temperatures in com-
vacuum jacket shall have a temperature sensor fastened to the
bination with its associated instrument at the time of first use
outer wall of the jacket at a point level with the vapor
and at least once per year thereafter as described in A2.2.2.
temperature sensor and opposite to the outlet arm of the head.
Alternatively, certified sensors may be used, provided the
6.5.3 The head shall be fitted with an adapter to support the
calibration of the sensor and its associated recording instru-
vapor temperature sensor so that it is held centered in the neck
ment can be traced back to a primary temperature standard.
with the top of the sensing tip 3 6 1 mm below the spillover
Recalibratewheneitherthesensorortheinstrumentisrepaired
point. This dimension can be checked by removing the
or serviced. (Warning—Vapor temperature measurement is
temperature sensor and inserting in its place a copper wire
one of the two major sources of error in distillation data.)
havingashortrightanglebendatthebottom.Byfeelingforthe
spillover point, the distance from the top joint of the adaptor 6.5.4.3 Verification of the calibration of the vapor tempera-
can be found. Laying the wire on the temperature sensor will ture measuring devices is to be made on a regular basis.
then permit checking of this dimension. Verificationatleastonceamonthisrecommended.Verification
D5236 − 03 (2011)
SYSTEM SIZE A B
25 mm 35/25 3 L
36 mm 65/40 6 L
50 mm 75/50 12 L
70 mm 102/75 24 L
FIG. 3 Distillation Flask
of the calibration of the sensors can be accomplish
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.