Note: Descriptions are shown in the official language in which they were submitted.
125S5C.a, 3
1 BACKGROUND OF THE INVENTION
2 This invention relates to a methanol fuel
3 composition with improved flame luminosity comprising
4 methanol and a select petroleum hydrocarbon mixture.
More particularly, this invention is directed to the
6 improved flame luminosity of methanol which results by
7 combining methanol with a petroleum hydrocarbon mixture
8 comprising selected aromatic and saturate/olefin frac-
9 tions to form an azeotropic mixture and which combi-
nation has a select boiling range.
11 The use of methanol as a fuel for various
12 needs, such as in spark ignition engines, is becoming
13 more and more of interest because of the varying
14 availability of different petroleum fuels and the
change in costs of such fuels. One of the problems
16 that exists with the use of methanol is that it burns
17 with a light blue flame that is almost invisible under
18 normal light conditions such as daylight or a lighted
19 room. Because it burns with such a nonluminous flame,
the use of methanol presents a special safety hazard,
21 especially when used as a fuel. Thus, a methanol spill
22 could be very dangerous since its ignition might not be
23 visible to people in the near vicinity.
24 The use of co-fuels such as volatile hydro-
carbons has been shown to enhance flame luminosity and
26 visibility as disclosed in "Use of Co-Fuels to Increase
27 the Luminosity of Methanol Pool Fires: Some Prelimi-
28 nary Findings" by J. E. Anderson and W. O. Siegl,
29 presented to Division of Petroleum Chemistry, Inc.,
A.C.S., Kansas City Meeting, September, 1982. As
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1Z~55~P3
1 generally shown in ~hi_ article, such combinations of
2 methanol with a co-fuel did not provide flame lumi-
3 nosity over the entire burning cycle.
4 Other teachings showed that flame luminosity
could be improved by adding gasoline, toluene or
6 reformate to methanol containing 5 and 10 vol. %
7 pentane. By adding 5% toluene to the pentane contain-
8 ing methanol fuel, the flame was visible until about 50
9 to 70% of the methanol was consumed. By using 15~
gasoline in methanol, a visible light persisted until
11 all the liquid was consumed. See "Environmental
12 Implication of the Use of ~lcohol-Fuel Highway
13 Vehicles" by E. E. Ecklund, T. J. Timbario and P. W.
14 McCallum, presented to the 75th Annual Meeting of Air
Pollution Control Association, New Orleans, June 20-25,
16 1982 and "Methanol Fuel Modification for Highway
17 Vehicle Use" by J. L. Keller, G. M. Nakaguchi and J. C.
18 Ware, Final Report, U. S. Dept. of Energy EY-76-C-04-
19 3683, published as NTIS document HCP/W3683-18, 1978.
While such methanol fuel combinations containing fairly
21 large amounts of gasoline do provide flame luminosity,
22 problems due to water sensitivity have developed.
23 Accordingly, there is the need to develop a
24 methanol fuel system which burns with a luminous flame
throughout its burning cycle and additionally does not
26 have any problems related to water contamination and
27 water sensitivity.
28 SUMMARY OF THE INVENTION
29 Now in accordance with this invention, it
has been found that a methanol fuel composition which
31 combines methanol with a select petroleum hydrocarbon
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l mixture has imprcved Elamc iuminosity and is relatively
2 water insensitive.
3 More particularly, this invention is
4 directed to a methanol fuel composition with improved
flame luminosity which comprises methanol and a
6 petroleum hydrocarbon mixture of:
7 a) at least about 2 volume ~ based on the
8 total volume of the composition of an aromatic hydro-
9 carbon fraction, said fraction including at least about
1 volume % based on the total volume of the composition
ll of aromatic hydrocarbons which distill substantially
12 uniformly over a wide boiling range having an initial
13 boiling point of less than about 240F and a final
14 boiling point of greater than about 375F, and
b) at least about l volume ~ based on the
16 total volume of the composition of a saturate/olefin
17 hydrocarbon fraction,
18 said petroleum hydrocarbon mixture having an
l9 initial boiling point of less than about 150F and a
final boiling point of greater than about 375F and
21 combines with the methanol to form an azeotropic mix-
22 ture which includes all of the methanol, said compo-
23 sition being capable of burning with a luminous flame
24 throughout its burning cycle and is effectively water
insensitive when small amounts of water are present.
26 Another embodiment of this invention relates
27 to the method of operating a spark ignition engine
28 comprising the improvement of using the methanol fuel
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1 composition of this invention which contains a par-
2 ticular petroleum hydrocarbon mixture and which burns
3 with a luminous flame throughout its burning cycle.
4 ~ETAILED DESCRIPTION OF THE INVENTION
As previously indicated, the present inven-
6 tion relates to a methanol fuel composition exhibiting
7 improved flame luminosity and comprising methanol and a
8 petroleum hydrocarbon mixture which includes select
9 aromatic and saturate/olefin fractions.
The select aromatic and saturate/olefin
11 fractions which comprise the petroleum hydrocarbon
12 mixture used in the composition of this invention can
13 generally be obtained from any of the commonly avail-
14 able petroleum hydrocarbon mixtures or crude oils. Such
petroleum materials usually comprise a mixture of
16 paraffinic, cycloparaffinic (naphthenes), olefinic and
17 aromatic hydrocarbons. The selected fractions are
18 obtained from the starting petroleum materials by
19 refining and separation techniques which are well known
in the petroleum art including distillation, cracking,
21 thermal diffusion, reforming etc.
22 The saturate/olefin hydrocarbon fraction of
23 the petroleum hydrocarbon mixture will generally
24 include paraffins, straight and branched chained, and
cycloparaffins as well as some olefins. The cyclo-
26 paraffins comprise not only the monocyclic compounds,
27 but the polycyclics and the alkyl substituted deriva-
28 tives thereof. While this fraction will generally be
29 derived from petroleum mixtures and crude oils where
the saturate components, i.e., paraffins and cyclo-
31 paraffins comprise the larger or predominant portion,
32 nevertheless, there may be some olefinic components
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1 present. In fac~, the fLâotior,s derived from some
2 operations, such as a cracking process, can contain
3 amounts of olefins which can vary up to about 20 vol.%
4 or even higher. Typical olefins will include the mono
and diolefins such as cyclopentadiene. The
6 saturate/olefin hydrocarbon fraction will generally
7 comprise at least about 1 volume % and preferably at
8 least about 1.4 volume %, such volume based on the
g total volume of the composition.
The aromatic hydrocarbon fraction will gen-
11 erally comprise at least about 2~ by volume and pre-
12 ferably at least about 2.5% by volume based on the
13 total volume of the composition and will contain a
14 number of different compounds. This aromatic hydro-
carbon fraction will include at least about 1 volume %
16 based on the total volume of the composition of a
17 mixture of aromatic hydrocarbons which distill sub-
18 stantially uniformly over a wide boiling range having
19 an initial boiling point of less than about 240F and a
final boiling point of greater than about 375F. By
21 distilling substantially uniformly it is meant that
22 this portion of the aromatic fraction will distill at a
23 fairly uniform rate, i.e., a rate such that the dis-
24 tillation curve (temperature vs. percent distilled) is
relatively smooth or even over the entire range and
26 does not sharply increase or decrease at any particular
27 point. In other words, this aromatic mixture will
28 comprise a number of different hydrocarbons which dis-
29 till at different temperatures throughout the desired
temperature range and are present in sufficient quan-
31 tities to provide distillation which is substantially
32 uniform, i.e. the distillation rate is generally smooth
33 or even over the temperature range. What in effect is
34 needed to obtain a generally uniform distillation is a
small amount, usually less than about 10 volume %, of a
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12~SS1~3
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1 large number of different ~ompounds. Typical compounds
2 found in the aromatic fraction are the alkylbenzenes
3 such as toluene, the xylenes and p-cymene, the poly-
4 cyclic aromatics such as naphthalenes, biphenyl,
acenaphthene, fluorenes, phenanthrenes, mononaphthene
6 benzenes and dinaphthene benzenes. It is understood
7 that branched or substituted ring components are also
8 included in the defined aromatic fraction.
9 Generally, both the aromatic and saturate/
olefin fractions will be comprised of a mixture of
11 compounds containing about 5 to about 12 carbon atoms.
12 Each fraction will generally contain a variety of
13 branched substituents and may contain small amounts of
14 sulfur and nitrogen content. In determining or
defining the aromatic and saturate/olefin fractions as
16 used in this invention, the procedure "Hydrocarbon
17 Types by FIA," ASTM D-1319 is used. A further descrip-
18 tion of petroleum hydrocarbon fractions of this type
19 and typical compounds in such petroleum compositions is
given in Kirk-Othmer, "Encyclopedia of Chemical
21 Technology," 2nd Edition, Vol. 14, pp. 845-855, 1967.
22 The petroleum hydrocarbon mixture comprising
23 the aromatic and saturate/olefin fractions as defined
24 herein will generally comprise at least about 3 volume
~ and preferably at least about 4 volume % of the total
26 composition; however greater amounts can be used with
27 cost efficiency being a prime factor in determining the
28 upper limit for the amounts to be used. The important
29 thing about this added petroleum hydrocarbon mixture is
that it form an azeotropic mixture which includes all
31 of the methanol. While the azeotrope could comprise
32 part of the petroleum hydrocarbon mixture itself, it
33 must include all of the methanol. This makes it pos-
34 sible for the petroleum mixture or luminosity component
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1 to be co-distilled ~ith the rethanol and to impart
2 luminosity as long as a flame exists. As noted
3 earlier, the select wide boiling aromatic component
4 which makes up part of the aromatic fraction, must
distill substantially uniformly over a range having an
6 initial boiling point of less than about 240F and a
7 final boiling point of greater than about 375F. The
8 petroleum hydrocarbon mixture, i.e. combined aromatic
9 and saturate/olefin fractions must have an initial
boiling point of less than about 150F and a final
11 boiling point of greater than about 375F. In
12 determining the boiling points of various components,
13 ASTM D-86Jis a procedure that is generally followed.
14 Another important advantage of using the
particular composition of this invention is that it is
16 relatively water insensitive to small amounts of water.
17 In using certain hydrocarbon components, such as
18 gasoline, other problems can develop when water is
19 present. Thus problems such as phase separation or
increased volatility can develop in such compositions
21 when fairly small amounts of water are present. The
22 composition of this invention has been found to be
23 water insensitive even when amounts of water of up to
24 about 3 volume % are present and still retains its
ability to maintain flame luminosity. By the term
26 "flame luminosity" as used throughout this application
27 is meant that the flame is clearly visible and distin-
28 guishable.
29 The composition of this invention may be
used in several applications but is particularly useful
31 as a fuel for operating a spark ignition engine.
32 Generally, the methanol will comprise the
33 major amount of this composition, i.e., at least about
~255S~3
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1 50 volume % and preferably ~t least about 80 volume %
2 based on the total volume of the composition.
3 ~ primer such as dimethyl ether is a par-
4 ticularly ~seful additive to the fuel composition of
this invention in certain applications since it pro-
6 vides good volatility at low temperatures to help in
7 cold starting. The amount of primer will depend on
8 ambient temperatures and the particular engine being
9 used. Typically about 2 to about 7 volume % based on
the total volume of the composition will be used.
11 Minor amounts of other additives generally
12 used with fuel compositions of this type may be
13 included in the composition of this invention, e.g.
14 corrosion and rust inhibitors, antioxidants, etc.
Typically, the total amount of other additives, i.e.,
16 besides the petroleum hydrocarbon mixture and primer,
17 will be less than about 1 volume % based on the total
18 volume of the composition.
19 Further details and illustrations of this
invention will be found in the following examples.
21 Example 1
22 A fuel composition comprising methanol and
23 optionally dimethyl ether primer was tested for flame
24 luminosity after adding a number of petroleum hydro-
carbon mixtures with the following results as shown in
26 the table below.
27 These results clearly show that composition
28 containing the amounts and the saturate/olefin and
29 aromatic fractions in accordance with this invention as
lZ~5503
1 shown by the use of the ~I'xed h~droformate or combi-
2 nations of toluene and light cat naphtha provide flame
3 luminosity over 100% of the entire burning cycle. In
4 contrast to this, other additive mixtures did not give
the desired flame luminosity at least not over the
6 entire burning cycle. Additionally, the compositions
7 in accordance with this invention were found to hold
8 more than 3 volume % water without phase separation or
9 a change in volatility.
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