Introductory practice: distillation, compiled by Kovács, András
Note: in this practical guidance students are asked questions (Q), by answering they
contribute to understanding the basis and the technique. This cannot be considered a
course material, but rather a note. Literature references have been omitted.
Objective of the test to familiarize with the operation of distillation, to learn how
to construct distillation curves and to assess the characteristics of fractions.
Engler distillation, Significance and Use, The basic test method of determining the
boiling range of a petroleum product by performing a simple batch distillation has
been in use as long as the petroleum industry has existed. It is one of the oldest test
methods under the jurisdiction of ASTM Committee D02, dating from the time when
it was still referred to as the Engler distillation. Since the test method has been in use
for such an extended period, a tremendous number of historical data bases exist for
estimating end-use sensitivity on products and processes.
The distillation (volatility) characteristics of hydrocarbons have an important effect
on their safety and performance, especially in the case of fuels and solvents. The
boiling range gives information on the composition, the properties, and the behavior
of the fuel during storage and use. Volatility is the major determinant of the
tendency of a hydrocarbon mixture to produce potentially explosive vapors.
The distillation characteristics are critically important for both automotive and
aviation gasolines, affecting starting, warm-up, and tendency to vapor lock at high
operating temperature or at high altitude, or both. The presence of high boiling point
components in these and other fuels can significantly affect the degree of formation
of solid combustion deposits.
Volatility, as it affects rate of evaporation, is an important factor in the application of
many solvents, particularly those used in paints.
Distillation limits are often included in petroleum product specifications, in
commercial contract agreements, process refinery/control applications, and for
compliance to regulatory rules.
Scope This test method covers the atmospheric distillation of petroleum products
using a laboratory batch distillation unit to determine quantitatively the boiling
range characteristics of such products . The test method is designed for the analysis
of distillate fuels; it is not applicable to products containing appreciable quantities of
residual material.
Petroleum products consists of mixture components, do not have a dedicated boiling
point, but a range and a distribution of boiling ranges. A distillation curve is a description
of the evaporation characteristic. Before having sophisticated instruments for composition
of petroleum products medium boil points and other derived characteristics have been
used to characterize the crude oil and in planning and controlling crude oil distillation
units. This is why we perform distillation of a gasoline and a gasoil sample. Every volatile
petroleum product specification prescribes this test for quality control.
 Initial boiling point: The temperature, corrected to the standard pressure (101.3kPa), of
the vapor stream in the standard distillation gear read in the moment of dropping the first condensate
into the graduated cylinder.
 Final boiling point: The temperature, corrected to the standard pressure (101.3kPa), of
the vapor stream in the standard distillation gear read in the moment of dropping the last condensate
into the graduated cylinder, or the temperature at which cracking in the flask takes place reflected by
drop in temperature of the vapor stream. When cracking takes place appreciable amount of liquid is
residing in the flask.
 Yield: the amount of distillate collected between the initial and final
distillation points. This is why it is important to measure the feed at condensation
temperature.
 Mean (volumetric) boiling point: average of temperatures read at evaporation
levels of 10, 30, 50, 70 and 90%:
tmV 

t10  t 30  t 50  t 70  t90 o
,  C
5
gear and apparatus
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a) flask
Operation:
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b) a representative apparatus
select the proper flask and thermometer
meter the oil to be tested by the use of a graduated cylinder at
temperature of the condenser. Attantion: a few boiling stones must be
added whenever a new boiling cycle commences. Care must be
attributed to avoid entering sample into the side tube.
Assemble the apparatus, open the cooling watr flow.
Start heating with care. The first drop must appear within 5-10 min if
gasoline, 10-15 min if diesel fuel constitutes the test material.
The rate of evaporation must be about 4-5 ml/min. Adequate heating
intensities must be set!
It is to control that the difference between t90 and final boiling point to
be about 3-5, respective 10 min.
Upon cooling to room temperature the apparatus is disassembled, the
amount of residual liquid is measured by the use of a graduated
cylinder of 10 ml capacity. The difference between the
residue+distilled to 100 ml constitute the loss in distillation.
Construct the distillation curve
2. Taking fractions
250 ml falsk is used in the Engler distillation apparatus. 100 ml gasoil is
distillad to 10 ml fractions.
Measure and record specific gravities and refractive indices of
fractions
Construct complex distillation curves with specific gravity and
refractive index values.
By the use of Watson diagram estimate the average molecular weight
of fractions.
Derived data: Cetane index
The Calculated Cetane Index formula represents a means for directly estimating the
ASTM cetane number of distillate fuels from API gravity and mid-boiling point. The
index value, as computed from the formula, is termed the Calculated Cetane Index
CCI = -420.34 + 0.016 G2+ 0.192 G log M + 65.01 (log M)2 - 0.0001809 M2
In which
G = API Degrees @ 60 oF
M = D86 Temperature @ 50% volume, in oF
In EN standards more than a single distillation mean value is used to calculate the CI
CI=45,2+0,0892T10N+(0,131+0,901B)T50N+(0,0523 - 0,42B) T90N+0,00049(T210N-T210N)+107B+60B2
where
T10N = T10 - 215; T10: 10 % (WV) distillation recovery temperature, °C
T50N = T50 - 260; T50: 50 % (WV) distillation recovery temperature, °C
T90N = T90 - 310; T90: 90 % (WV) distillation recovery temperature, °C
B  e0.0035DN 1
DN = D - 850; D is the density at 15°C, kg/m 3
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Write a report and a conculsions of the test.
Mérési jegyzőkönyv
1. desztilláció_
Mérés megnevezése,
Jegyzőkönyvet
készítette
Dátum
Jellemző
Minta jele
Desztilláció
Kezdő forráspont, °C
T10, °C
T20, °C
T30, °C
T40, °C
T50, °C
T60, °C
T70, °C
T80, °C
T90, °C
T25 °C
vfp °C
Hozam, ml
Maradék, ml
Veszteség, ml
Érték
Megjegyzés
Ismertető
2. frakcionálás _
Jellemző
Frakció száma
Forráspont határok,
°C
1
2
3
4
5
6
7
8
9
10
3. görbék
4. kiértékelés
Sűrűség, g/cm3
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n D20
M, számított