Fuel additive

It has been discovered that a fuel additive comprising a major proportion of a high molecular weight amine, and minor proportions of naptha and a poly alpha olefin synthetic oil, together with a small amount of a biocide can be combined with distillate fuels such as kerosene and diesel fuels in a ratio of about one part additive to about 3,000 to about 10,000 parts of fuel to produce a polymerization and bacteria inhibitor, as well as a rust inhibitor which is capable of depolymerizing and dispersing sludge and sludge forming polymers in stored fuel.

BACKGROUND OF THE INVENTION 
This invention relates to fuel additives and more particularly to diesel 
fuel additives which inhibit the polymerization of fuel components, the 
growth of bacteria in stored fuel, and corrosion inside the fuel tank. 
With the increasing prevalence of standby power generation equipment for 
essential services, including hospitals, communication equipment and the 
like, it has become increasingly important to protect the fuel from 
degradation when stored for long periods of time. More recently, many of 
these standby motor generator systems have employed diesel engines making 
the stability of stored fuel an even more important consideration. 
Distillate fuels in general and diesel fuel in particular are prone with 
prolonged storage to form polymerizates which agglomerate into what is 
referred to as sludge which can clog fuel lines and fuel injectors 
preventing the reliable operation of the engine. In addition, water in the 
fuel and in the form of condensates in a partially filled storage tank 
will attack the metal of the tank forming rust which also promotes the 
polymerization of components in the fuel. 
In addition, new regulations promulgated by the Environmental Protection 
Agency have recognized the problem of rusting tanks and require measures 
to prevent contamination of ground water which can occur from fuel leaking 
underground from rust perforated tanks. 
Likewise, sludge formation can be accelerated by the growth of bacteria in 
the fuel. 
Therefore, modern inhibitors should have the following characteristics in 
use. 
The material should be a sludge dispersant. It is known that the 
deterioration of fuel oils involves polymerization reactions resulting in 
the agglomeration of macroscopic polymerizates into sludge. Although this 
reaction may be initiated by oxygen, additives containing antioxidants, 
such as hindered phenols or diamines of the types used in gasolines as gum 
inhibitors, are not totally effective for the purpose of preventing the 
polymerization mechanisms. The additive materials should also have 
rust-preventive properties. The additive materials should also be 
effective when the fuels are stored in the presence of metals and water 
and rust. The additive materials should also inhibit the propagation of 
bacteria. 
The kinds of bacteria that grow in stored fuels thrive on nitrogen, sulfur, 
and phosphorus, as well as iron, generally in the form of its oxides. 
Bacterial growth can be reduced, if not eliminated, by employing the 
following preventive measures. A biocide should be employed. Of course, 
the elimination of materials in the fuel tank that contain nitrogen, 
sulfur or phosphorus would be helpful. Since the latter measure is 
practically impossible, these materials must be considered in the 
formulation of any additive. In addition, it is important to keep the fuel 
tanks clean and dry, in order to reduce or eliminate rust formation in the 
tanks. 
Two standard test methods have been used as the best yardstick of an 
inhibitor's usefulness in prolonging fuel storage life. The first test is 
a variation of the color-stability test in Federal Specification VV-K-211 
Kerosene. In addition to observing the color change, the amount of 
filterable sludge and sediment is also measured. The second test is a 
prolonged version of the Gulf Oil Company's Fuel Corrosion of Steel Test. 
The Bell Laboratories' version of these tests have been correlated against 
fuels actually stored in a stand-by power fuel tank. The first test is run 
at 210.degree. F. until an observable amount of sludge has formed. This 
test is essentially an accelerated heat-stability test and is run in the 
absence of water. The second test is run at 120.degree. F. over water in 
the presence of 1020 steel strip. This test is concluded after 12 weeks or 
when an observable quantity of rust and sludge has been deposited. 
The accelerated heat-stability test is comparatively quick and useful for 
screening out the poorer additives; but because water is absent from this 
test, it is not capable of differentiating between those additives that 
are either ineffective rust inhibitors, or incapable of protecting the 
fuels when stored in contact with water and steel, and those that are 
effective under such storage conditions. It is precisely these conditions 
that are of importance since stand-by fuels are frequently in contact with 
metal and condensate water, and rusting may be often as severe a problem 
as sludge formation. A 12-week stability-and-rust test was designed to 
evaluate these effects. 
Because of the importance of stabilizing the fuels for extended periods of 
up to 10 years with the fuels in contact with metal and water, it is also 
important that the additive exhibit properties which would enable it to be 
used as a reinhibitor and depolymerizer during its repeated use over 
prolonged periods of time. 
The major oil companies and chemical manufacturers have provided a wide 
variety of inhibitors. Exemplary of the types of materials available are 
the following: 
(1) nitrogen-containing, surface-active polymers such as duPont FOA-11 and 
duPont FOA-208. 
(2) organic-soluble, surface-active, oxygenated amine such as Enjay 
Paradyne HO4. This product may also contain a minor amount of a polymeric 
dispersant. 
(3) anionic fuel additives such as Apollo SDI-2R, a proprietary sludge 
inhibitor and dispersant as well as rust preventive, manufactured by 
Apollo Chemical Corporation. 
(4) chelating-type metal deactivator such as an 80% solution of 
N,N'disalicylidene-1-2propanediamine in aromatic solvents. 
(5) A film-forming metal deactivator such as Vanlube 601, R. T. Vanderbilt 
Company. 
(6) an antioxidant such as 2,6 ditertiarybutyle-4-methylphenol provided in 
Enjay Parabar 441, and also, duPont A029. 
To varying degrees, these materials alone or in various combinations have 
in the past provided some measure of protection for stored fuel with 
respect to some of the major properties required. 
For very long term storage however, it is essential that the inhibitor 
employed be capable of being employed during routine maintenance to 
depolymerize and disperse the sludge that is inevitably formed. 
It is also important that attempts to eliminate the problem of injector 
clogging at low temperature by the build up of hydrocarbon waxes in the 
fuel does not compound injector scoring problems by reducing or 
eliminating the lubricity of the fuel. It is therefore an objective of the 
present invention to provide a diesel fuel additive which inhibits the 
formation of sludge, and bacteria, in the fuel during long periods of 
storage. It is a further objective of the present invention to provide a 
fuel additive which inhibits the formation of rust in diesel fuel storage 
tanks. 
It is yet another objective of the present invention to provide a fuel 
additive composition which is capable of depolymerizing and dispersing 
sludge and sludge forming polymers in diesel fuel and kerosene stored for 
long periods of time. 
BRIEF SUMMARY OF THE INVENTION 
It has been discovered that a fuel additive comprising a major proportion 
of a high molecular weight amine, and minor proportions of naptha and a 
poly alpha olefin synthetic oil, together with a small amount of a biocide 
can be combined with distillate fuels such as kerosene and diesel fuels in 
a ratio of about one part additive to about 3,000 to about 10,000 parts of 
fuel to produce a polymerization and bacteria inhibitor, as well as a rust 
inhibitor which is capable of depolymerizing and dispersing sludge and 
sludge forming polymers in stored fuel.

DETAILED DESCRIPTION OF THE INVENTION 
As previously described, a wide variety of chemical compositions have been 
provided as fuel additives. Unfortunately, many of these compositions when 
used as recommended by their manufacturers do not provide all of the 
properties which overall are required in an effective inhibitor, or 
reinhibitor and depolymerizer for the long term storage of kerosene and 
diesel fuel. 
The composition of the present invention utilizes a major proportion of a 
proprietary composition presently sold by the Ethyl Corporation under the 
trademark EDA3. 
This clear amber liquid composition contains a high molecular weight amine, 
is basic and is believed to be a polymerization product of an analog or 
homology of ethylene diamine. The boiling point range of this composition 
begins at about 240.degree. F. (116.degree. C.). It is insoluble in water 
and has a density at 68.degree. F. (20.degree. C.). This composition is 
recommended by the manufacturer as the sole fuel additive to be used as an 
inhibitor of sludge formation. In addition to the foregoing, the EDA-3 
contains additives which inhibit rust, such as certain chelating agents, 
and which help to demulsify and disperse sludge that is formed. 
At 100% usage however, this composition does not properly diffuse in the 
fuel sufficiently to effectively provide any depolymerization function. 
When this composition is diluted with an aromatic solvent, such as naphtha 
in a manner contrary to the recommendation of composition, manufacturer in 
the proportions described hereinafter, the combination provides a more 
workable, effective depolymerizing agent which also helps to prevent wax 
build-ups which can be a problem in severe cold. Preferably, a naphtha, 
purchased from Union Chemicals Division of Union Oil Company of 
California, designated HA-40, is used. This composition contains single 
and double ring aromatics having a boiling range of from about 420.degree. 
F. (216.degree. C.) to about 545.degree. F. (285.degree. C.) and a 
specific gravity at 60.degree. F. (16.degree. C.) of about 0.98. This 
composition is also not soluble in water. 
Due to the strong solvent action of the naphtha, it is desirable for the 
composition to contain a minor proportion of a poly alpha olefin, 
non-compounded synthetic oil such as Synfluid 6 cs sold by the Gulf Oil 
Company. This aliphatic hydrocarbon based synthetic oil, when used in the 
composition in about 25 parts per 100 parts of total composition, helps to 
provide the required lubricity for diesel injectors, pumps and the like. 
Finally, most fuel additive compositions attempt to prevent polymerization 
due to bacteria growth and the subsequent sludge formation, by the use of 
up to 5% by weight of a biocide. Contrary to this prior practice, it has 
been found in the present composition that about 0.05 parts per 100 parts 
of the composition is an adequate level for the biocide selected. The 
preferred biocide used in the present invention is 
Hexalydro-1,3,5-Tris(2-Hydroxyethyl)S-Triazine (C.sub.9 H.sub.2, N.sub.3 
O.sub.3). This component is sold by ONYX Chemical Company of Jersey City, 
N.J. under the trademark ONYXIDE 200. 
To properly prepare the composition of the present invention, the ONYXIDE 
200 is first added to one half of the HA-40. The poly alpha olefin is then 
added to the HA-40 and ONYXIDE 200. Next, the EDA-3 is added to the other 
half of the HA-40 and then the two HA-40 components are thoroughly mixed 
together. 
The most preferred composition contains the following proportions: 
50 parts by weight EDA-3 
24.95 parts by weight HA-40 
25 parts by weight of Poly alpha olefin 
0.05 parts by weight ONYXIDE 200. 
As previously discussed, the prior compositions for inhibiting the 
formation of sludge forming polymers, bacteria, and for the prevention of 
rust in fuel storage tanks were not particularly effective when 
subsequently applied to fuel storage tanks where polymerization and sludge 
had already formed to any substantial extent. Without being bound to any 
particular theory, it is postulated that macroscopic sludge, even if 
temporarily solubilized by other additive compositions, such as present in 
EDA-3, tends to reagglomerate relatively quickly thereby posing the same 
drawbacks to the fuel pick up, transfer and engine injector systems. 
The composition of the present invention after successfully solubilizing or 
subdividing the macroscopic sludge also provides the capacity of 
dispersing the submacroscopic sludge agglomerates thereby retarding 
subsequent reagglomeration. This action in concert with the inhibition of 
polymerization provided by the components of the composition, in the 
quantities recited has been shown to be an effective fuel additive for 
stored fuel when used in a routine program of preventative maintenance. 
The particular action described apparently minimizes the effect of 
bacteria, oxygen and even rust formation on the polymerization mechanisms 
that can occur in stored fuel. 
Since none of the prior compositions completely eliminate the formation of 
agglomerated polymerizates in the form of gels and sludge it has been 
important to find a composition and method for reducing the deleterious 
effects from such activity. In comparison tests, such as those previously 
employed, the composition of the present invention has provided a hitherto 
unachieved benefit in this field. 
The present invention has been described in its most preferred embodiments. 
The scope of this invention is not intended to be restricted by this 
disclosure but rather only by the applicable prior art as applied to the 
appended claims.