1. business and industrial
2. energy
3. oil

Journal of Science and Technology
2 (1), 2008, 76-85
©BEYKENT UNIVERSITY
ADDITIVES FOR HIGH QUALITY
GASOLINE PRODUCTION
Hisham BAMUFLAH*, Salah A. ABDULLAH* and Yavuz
YORULMAZ**
*Chemical Engineering Dept. King Abdulaziz University, Jeddah Saudi
Arabia
**Chemical Engineering Dept. Beykent University, İstanbul, Turkey,
e-mail:[email protected]
Received: 10 June 2007, Revised: 15 September 2007, Accepted: 29 December 2007
ABSTRACT
Gasolines are liquid fuels produced by refining operations for transport
purposes. In this study, gasoline properties are studied for ideal purposes
and compared and compared with each other for different additives. The
octane value, RVP, IBP, 10%, 30%, 50%, 70% and FBP vaporization
temperatures were the main properties studied and their predictions for a
blend from its components were the utmost importance. The correlations
obtained from the actual blending data by multiple regressional ana-lysis
produced better results as compared to the ones obtained from the
classical methods.
Key Words: Gasoline, octane
multiple regressional
analysis.
number,
Reid vapor pressure,
blend,
YÜKSEK DEĞERLİ (OKTAN) BENZİN
ÜRETİMİNDE KATKI MADDELERİ
ÖZET
Benzinler sıvı yakıtlardan olup, taşınımda kullanılmak amacıyla rafineri
işlemlerin de üretilirler. Bu çalışmada en iyi kullanımları için, benzin
özellikleri çalışılmış ve farklı katkı maddeleri için elde edilen değerler ile
kıyaslamalar yapılmıştır. Oktan sayısı, RVP, IBP, 10%, 30%, 50%, 70%,
ve FBP buharlaşma sıcaklıkları başlıca çalışılan özellikler olup ve bir
karışım için bileşenlerin verilerinden bu değerlerin saptanması en büyük
76
H. BAMUFLAH, S. A. ABDULLAH and Y. YORULMAZ
amaç idi. Multiple regression analiz yöntemi ile bileşenlerin gerçek
değerlerinden elde edilenkorrelasyon bağlantıları, klasik yöntemler ile
elde edilenlerden daha iyi neticeler verdiği görülmüştür.
Anahtar Kelimeler: Benzin,
multiple regression analiz.
oktan sayısı, Reid buhar basıncı,
paçal,
1. INTRODUCTION
Liquid fuels are much easier to handle than solids and more convenient to
store than gases or electricity. Motor gasoline is made up of a number of
components depending on the complexity of the refinery. The gasolines
are colorless mixtures of volatile hydrocarbons obtained from liquid
petroleum fractions which boil within the temperature range of about
30 C - 200 C
and prepared by blending various liquid stocks obtained in
refining operations. This number ranges from as low as a few to as many
as fifteen.
Volatility is the tendency of liquid to evaporate or change from liquid to
gaseous state. It depends on the nature of the liquid and its storage
temperature. Reid vapor pressure (RVP) is the vapor pressure of the
gasoline at about 3 8 C . The volatility of gasoline must be carefully
balanced to provide the optimum compromise among performance
features that depend on the vaporization behaviour,[1].
Octane number is defined as the percentage by volume of iso-octane that
must be mixed with normal heptane to match the the knock intensity of
the fuel undergoing testing. There are two recognized laboratory engine
test methods for evaluating the antiknock performance of motor fuels,
namely the research and motor method . Octane value of a gasoline is
one of the most important properties to reflect idea about smooth and
proper fuel combustion in gasoline type engines. For this reason, finished
product gasolines have to meet certain octane value standards and
todays gasoline must meet certain specifications,[2] and [3].
2. THEORY
Gasoline blends prepared usually can not meet the required octane value
as they are. For this reason additives methyl ethyl lead (MEL), tetra ethyl
lead (TEL) are used as octane booster. The domestic gasoline octane and
lead content are currently set at 95 RON (minimum) and 0.4 grams per
liter (maximum). The non-linear effect of gasoline composition on octane
77
Additives For High Quality Gasoline Production
rating is of great importance in planning refinery operations. For the
required component properties from the early studies are the volume
percent olefins, the octane rating for the given test method and TEL
concentrations for the components having low concentrations of sulfur
and sulfur compounds. The octane rating of a blend given composition is
predicted by the following equation , [4].
£
VDt (R + CP)
£ VD>
Where, Vi is the volume of component i added to blend , Pi is the olefin
difference, Ui - U m i x , volume percent, Di is the A weighing factor, given
- APt
as Di= (APi)/(1-e
' ), Ri is octane rating of component i by the given
test method, C is 0.130 for research octanes and 0.097 for motor octanes
and A = 0.01414 for research octanes and 0.0199 for motor octanes.
TEL remains an economic antiknock additive to produce gasolines and it
basically
increases the gasoline resistance to engine knocking which permits the
addition of greater quantities of lower octane components like naptha and
FCCU gasoline into gasoline pool.
However, since the 1970's, environmental policies and regulations in the
world major markets have put pressure on the refiners to phase out leaded
gasoline to curb excessive emission of hydrocarbons, NOx and COx.
Lead poisons the catalytic converters in the exaust system of automobiles
and makes the converters ineffective for reducing the emissions of
pollutants produced by engines, [5].
For some time alcohols appeared a as a fuel in the form of a blend or
gasoline extender for partly or complete replacements for gasoline. The
two alcohols that have received most attention are methanol and ethanol
being convenient end products from biomass. Alcohols are composed of
carbon, hydrogen and oxygen and are described as oxygenated fuels
being different from hydrocarbons. The oxygen has the disadvantage that
it adds nothing to energy content but increases the weight. The good
combustion qualities of methanol and ethanol with their suitability as
spark ignition fuels are shown by their high research octane in Table1.
The high octane number is an indication of a fuel's combustion efficiency
in a spark ignition engine and enables alcohols to be used in engines with
78
H. BAMUFLAH, S. A. ABDULLAH and Y. YORULMAZ
higher compression ratios. This together with their wider flammability
limits which allows for clean burning gives rise to more efficient
combustion.
Table 1. Alcohols and Gasoline Fuels Properties
Premium
Methanol
Ethanol
Gasoline
Research Octane
114
111
98
Number
Percent Oxygen
50
35
0
(by weight)
Air:fuel
6.5:1
9.0:1
14.7:1
combustion ratio
Compression
12:1
12:1
9.5:1
ratio
Boiling range, C
64
78
25-225
Gasoline engines the energy contained in the alcohol can be used that
much more effectively than the energy contained in gasoline. However,
alcohols are much less energy intensive than gasoline: one liter of ethanol
contains 40 per cent less energy and one liter of methanol 55 percent less
energy than a liter of gasoline. Therefore, even with the higher thermal
efficiency the net result is an increase in the volume of fuel required per
kilometer travelled. The handling of alcohols
has to take into
considerations that they are corrosive to certain metal and plastics which
could be found in the distribution network and vehicle fuel systems.
Methanol has the additional hazard of being extremely toxic and its skin
contact mus be avoided. There isn't any major lubrication problems with
ethanol but methanol may cause increased wear to parts of the engine,
rusting and the formation of deposits in the inlet system and consequently
require special lubricants and additives. Inadvertent ingestion of
methanol, such as when one siphons fuel from a vehicle could pose more
of a threat than gasoline because of color and odor lacks.
There is continual competition between the use of toluene as gasoline
additive and main raw material for petrochemical industry. Most of the
time toluene's market price will be close to its value as a gasoline
blending component. Blending value is expected to increase steadily due
to octane its octane capability. Supplies of toluene for gasoline will be
relatively constant and can not be expected to play major factor in solving
the octane shortage, [6].
79
Additives For High Quality Gasoline Production
The other possible gasoline blending component has received a great deal
of publicity is methyl tertiary butyl ether (MTBE). Much of data refers to
its effect on the octane number but not much on its effect on gasoline
volatility. Generally, the addition of MTBE increases gasoline volatility
to acceptable degree but no significant effect. However M T B E can mix
with hydrocarbons by any percentage
and does not cause the
characteristics of separation layer. Its research and motor octane numbers
are upto 117 and 101 respectively. It does not affect on the material and
easy to transfer from place to place. When it is added to gasoline it
reduces the amount of carbon monoxide and hydrocarbons. Generally it
can be mixed with gasoline by 10-11% (by volume) and sold under the
trade name 'gasohol'.
The other options involve blending high octane components are ETBE
(ethyl tertiary butyl ether) and TAME (tertiary amyl methyl ether). These
organic compounds contain oxygen and their use has increased in order to
reduce emissions of engine pollutants. The addition of oxygenates raises
the combustion temperature in the engine and improves its efficiency
with low RVP characteristics.. Their comparative stydies are given in
literature, [7].
3. PROCEDURE AND DISCUSSION OF RESULTS
The effects of various amounts of methyl ter-butyl ether to car gasolines
are studied and the results are given in Table 2, [8].
Table 2. The Effects of Methyl Tertiary Butyl Ether to Car Gasolines
0 % Addition of M T B E
Gasoline(2)
Gasoline(3)
Volume %
Gasoline(l)
Composition
Straight Run Gasoline
10
C5-C6 isomerate
50
Reformate
90
50
59.6
Light Cat. Cracking
22.9
Gasoline
Heavy Cat.Cracking
6.1
Gasoline
C3-C4 Alkylate
11.4
Research Octane Number
84.6
90.5
93.7
(RON)
Motor Octane Number
84
79
83
(MON)
80
H. BAMUFLAH, S. A. ABDULLAH and Y. YORULMAZ
RON (for the final
product)
M O N (for the final
product)
RON (for the final
product)
M O N (for the final
product)
RON (for the final
product)
M O N (for the final
product)
5% Addition of M T B E
92.2
87
94.9
84
80.6
84.6
10% Addition of M T B E
88.9
93.7
82.4
96
85.1
85.4
15% Addition of M T B E
95.2
90.8
97.2
86.4
86.5
83.8
This project work aimed at the premium gasoline produced at Jeddah Oil
Refinery in Saudi Arabia and prediction of its Reid Vapor Pressure and
temperatures at given percent vaporized from components distillation and
composition data supplied by the same institution. The correlations
established using a multiple regression computer program to correlate the
blend RVP and percent vaporized temperature using the data of the blend
components which are given in Table 3, [12].
Properties
Table 3. Components Data For Gasoline Blends
PLATFORMATE
LSR
FCCU
0.673
Sp. Gr. @60
F
API
78.8
RVP, bar
0.72(10.5)
(psig)
Sulfur, %wt
0.027
Distillation, C
IBP
36
10%
49
Vaporized
50%
69
Vaporized
90%
91
Vaporized
FBP
113
0.762
0.738
nBUTANE
0.574
54.1
0.62(9.0)
38.8
0.62(9.0)
113.1
3.42(48.6)
0.0
0.16
--
39
61
37
55
---
122
107
--
165
193
--
200
220
--
81
Additives For High Quality Gasoline Production
Recovery,
%
Residue, %
Loss, %
RON, Clear
98
97.3
97.7
--
0.7
1.3
63
1.3
1.4
87
1.3
1.0
89
--92
The dependent variable was denoted as RVP Wend and the independent
variables were the RVP values for each component times the volume
percent of each component. The Table 5 shows the results of correlation
between the RVP of blend and the RVP of its components. It was
observed that a good fit results with a multiple correlation of 0.988%.
Table 5 also shows that the percent error is very small with a minimum
value of 0.09%, a maximum of 3.18% and average value of 1.105%.
Therefore the following equation is concluded for correlated RVP of a
premium gasoline from its components:
RVP blend = 6.097+( 1.749 (RVP1 X V1))+(1.285 (RVP2 X V2))+(1.97
((RVP3 XV3)) +(1.16 (RVP4 X V4))
Where; RVPi: Reid vapor pressure of component 'i'and Vi : Volume
percent of component 'i' the results obtained from our developed
correlation can be compared with those from classical method which
involved the use of index tables. As it is seen from Table 4, our
correlation results with low average percent error.
| Table 4._ Comparison of Estimated RVP blend With Experimental Values
% DEVIATION
Observed Points OBSERVED ESTIMATED
1
9.13
9.20
0.76
2
9.94
10.0
0.60
3
10.80
10.76
0.37
4
11.60
11.59
0.09
0.44
5
9.0
8.96
-1.63
6
10.40
10.5
7
8.50
8.59
-1.06
8
8.50
8.77
-3.18
9
8.90
9.05
-1.69
9.04
-0.44
10
9.00
11
0.22
9.30
9.28
12
9.20
8.98
2.39
13
0.22
9.30
9.28
14
9.20
8.98
2.39
82
H. BAMUFLAH, S. A. ABDULLAH and Y. YORULMAZ
Average Absolute Deviation = 1.105313
As for IBP equation for premium gasoline the following equation is
obtained:
IBP blend = 47.307 - 22.330 P(1) 3 + 12.045 P(2) 3 _ 1280.636 P(3) 3 48.925(3) P(1)+P(2) 2 -112.106 (3)P(1) P(3) 2 +36.412
P(2)P(1) 2 -7.827(3)P(3)P(1) 2
where: P(1) = IBP(1) 0 2 9 X VOL(1)
P(2)= IBP(2) 0 2 9 X VOL(2)
(3)
P(3)= IBP(3) 0 29 X VOL(3)
IBP(1) = Initial Boiling Point of FCCU gasoline
IBP(2) = Initial Boiling Point of PLATFORMATE
IBP(3) = Initial Boiling Point of LSR naptha
VOL(1) = Volume Percent of FCCU gasoline
VOL(2) = Volume Percent of PLATFORMATE
VOL(3) = Volume Percent of LSR naptha
In a similar way T10% b l e n d is correlated to T10% of components as
that of IBPblend. The same thing applies to Ts0% blend and T90% blend
temperatures.
3
3
3
T10% b l e n d = -7.489 + 1.531 x X(1) -21.803 x X(2) - 381.947 x X(3)
+ 8.8360 x 3 x X(1) x X(2) 2 + 37.000 x X(1) x X(3) 2 _ 1.646 x 3 x X(2) x
X(1) 2 -0.229 x 3 X(3) x X(1) 2
Where: X(1) = T10%(1)0 35 x VOL(1)
X(2) = T10%(2)a35x VOL(2)
X(3) = T10%(3)a35x VOL(3)
T10%(1) = 10% distillation temperature of FCCU gasoline
T10%(2) = 10% distillation temperature of PLATFORMATE
T10%(3) = 10% distillation temperature of LSR naptha
= 111.679 _ 60.374 x Y(1) 3 + 229.727 x Y(2) 3 - 1706.069
x Y(3) -184.203 x Y(1) x Y(2) 2 + 143.531 x 3 x Y(1) x Y(3) 2 + 111.476
x 3 x Y(2) x Y(1) 2 _ 10.930 x 3 x Y(3) x Y(1) 2
Where;
Y(1) = T50% (1) 0 2 1 x VOL(1)
Y(2) = T50% (2)0.21 x VOL(2)
Y(3) = T50% ( 3 f 2 1 x VOL(3)
T50%(1) = 50% distillation temperature of FCCU gasoline
T50%(2) = 50% distillation temperature of PLATFORMATE
T50%(3) = 50% distillation temperature of LSR naptha
T90% b l e n d = 151.110 - 37.251 x Z(1) 3 + 500.205 x Z(2) 3 + 790.175 x
3
Z(3) -230.511x3 x Z(1) x Z(2) 2 _ 66.579 x 3 x Z(1) x Z(3) 2 + 101.838 x 3
x Z(2) x Z(1) 2 + 14.964 x 3 x Z(3) x Z(1) 2
Where;
Z(1) = T90%(1)015 x VOL(1)
Z(2)= T90%(2)0.15 x VOL(2)
Z(3)= T90% (3) 0 . 15 x VOL(3)
T50% blend
3
83
Additives For High Quality Gasoline Production
T90% (1) = 90% distillation temperature of FCCU gasoline
T90% (2) = 90% distillation temperature of PLATFORMATE
T90% (3) = 90% distillation temperature of LSR naptha
As for FBP value of the blend, the following equation has been obtained:
FBP blend = 226.567 -135.593 x R(1) 3 + 2411.704 x R(2) 3 + 2204.347 x
3
R(3) -930.966 x 3 x R(1) x R(2) 2 - 148.257 x 3 x R(1) x R(3) 2 + 356.208
x 3 R(2) x R(1) 2 + 6.511 x 3 x R(3) x R(1) 2
Where;
R(1) = FBP(1) 0 3 0 x VOL(1)
R(2) = FBP(2) 0 30 x VOL(2)
R(3) = FBP(3) 0 30 x VOL(3)
FBP(1) = Final boiling point of FCCU gasoline
FBP(2) = Final boiling point of PLATFORMATE
FBP(3) = Final boiling point of LSR naptha
4. CONCLUSION
The effects of Reid vapor pressure and distillation characteristics on
gasoline production are studied with actual cases. Restricting the lead
content of gasoline causes changes in gasoline properties and may
necessitate a change in specifications. Simple classical methods are not
very conducive for RVP and distillation temperatures calculations from
components data.
Correlations produced from multiple regression
analysis method are more indicative and accurate in calculating blend
properties for each
refinery.
ACKNOWLEGMENT
W e extend our appreciation to Jeddah Oil Refinery
contribution to our research Project.
for their valuable
REFERENCES
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[3]. The Story of Gasoline, Ethyl S.A., 100, Park Avenue, New York, U.S.A.
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Dec., 1959.
[5]. Shell Briefing Service, Alternative Road Transport Fuels, No 5, 1982.
[6]. Dosher R. John, Toluene: Octanes or Chemicals, Hydrocarbon Processing,
May1979.
84
H. BAMUFLAH, S. A. ABDULLAH and Y. YORULMAZ
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85