DE1157035B - Preservation of water-based kerosene fuels against bacterial growth - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY
GERMAN / Mfm PATENT OFFICE

kl. 46 a ⁶ 7

INTERNAT.KL. ClOl

EXPLAINING EDITORIAL 1157 035

St 18464 IVd / 46a ⁶

REGISTRATION DATE: OCTOBER 23, 1961

NOTICE
THE REGISTRATION
AND ISSUE OF
EDITORIAL: NOVEMBER 7, 1963

The invention relates to the preservation of water-containing kerosene fuels against bacterial growth when storing.

It is known that hydrocarbon fuels when stored in storage tanks, such as. Am Oil refineries, distribution stations and in the tanks for engine fuels, almost always small quantities Contain water at the bottom of the container. Some bacteria and sponge species commonly found in found in the earth and in the groundwater, also occur in the water at the bottom of such reservoirs and extract the nutrients they need from the hydrocarbon phase, as well as those in the water phase contained trace elements. Due to this metabolism, certain amounts of petroleum products are produced consumed; this metabolism is also the cause of the corrosion of the tanks and causes the general product pollution due to the formation of rust, hydrogen sulfide, rubbery Products, peroxides, acids, colored substances and hair fiber products in the border zone between the water and the hydrocarbons.

Bacteria seem to prefer hydrocarbons with a long carbon chain as food. Therefore, the abovementioned bacteria are found particularly frequently in kerosene stores stored in water deposits, and the life of these bacteria there is far more difficult to control than in water deposits stored gasoline stocks. Gasoline generally has a final boiling point below 238 ° C and often below 228 ° C. Even if the final boiling point is 238 ° C, the amount which has a boiling point above 228 ° C rarely exceeds 10%. Gasoline has at least 40% components with a boiling point below 120 ° C. In the following, the term »kerosene« is intended to include hydrocarbon fuels in which at least 30% of the components boil above 228 ° C or in which no more than 15% of the components boil below 120 ° C or both criteria apply. Kerosene stocks are almost always unleaded, ie they do not contain any tetraalkyl lead compounds. Such products include diesel oil, which is a fraction of crude oil with a boiling point between about 150 and 370 ° C and of which at least 90 ¹⁰ zo boil above 205 ° C, and jet fuels for turbo-propellers or jet planes. These last-mentioned fuels are mixtures of petroleum fractions which have to meet a number of requirements and which have a boiling range of approximately 38 to 315 ° C. and are preferably water-containing

• Kerosene fuel against bacterial growth

Applicant:

The Standard Oil Company, Cleveland, Ohio (V. St. A.)

Representative: Dr.-Ing. Dr. jur. F. Redies,

Dipl.-Chem. Dr. rer. nat. B. Redies

and Dr. rer. nat. D. Türk, patent attorneys,

Opladen, Rennbaumstr. 27

Claimed priority:
V. St. v. America of October 27, 1960 (No. 65 273)

Richard John DeGray, Shaker Heights, Ohio,

and Lawrence Neil Killian,

Bedford, Ohio (V. St. A.),

have been named as inventors

2

between about 65 and 290 ° C. The following data are used to explain a particular one Fuel, namely JP-4, which is a fairly broad fraction of petroleum.

Distillation sample

20% evaporates at 132 ° C

50% evaporates at 182 ° C 90% evaporates at 244 ° C

Residue 1.5 percent by volume

Loss 1.5%

Sulfur content .. max. 0.4 percent by weight

Melting point - 60 ° C

Kcal / kg 2093

Flash point -12 ⁰ C

As seen from the above, boil about 35% of the components above 205 ⁰ C. In the JP-5 fuel boiling between 80 and 90% above 205 ° C.

In a narrow fraction of kerosene with a boiling point

309 747/199

at 150 ° C ± 4 ⁰ C, none of the components boil below 120 ° C.

Also, kerosene stocks appear to be a water-in-oil emulsion more than gasoline stocks to stabilize that by microbiological Activity generated mud and fibrous matter is caused. Hence, much of this remains Impurities in the kerosene phase are suspended and easily clogged filters and sieves in the storage area Transport devices and the filters of machines that run on kerosene.

Clogging of the filters is a particularly serious one because of the potential for engine failure Moment in jet planes that are operated with kerosene-type fuels. aside from that the tendency to blockage of filters in jet machines is increased by the special design of these machines and the way they work. The amount of one machine made by one Jet fuel consumed is very large and can go up to 47001 per hour or more be. With such large amounts of liquid, very low concentrations of contaminants can occur Substances very quickly become disruptive amounts of residue in the machine's filter system. aside from that a jet aircraft has a large number of interconnected instead of a single fuel tank Cells with numerous deep spots in which water can collect and in which the bacteria can live. In many jet aircraft, and especially in military aircraft, these are Fuel cells practically inaccessible to cleaning or rinsing, and microbial growth can go on undisturbed and unaffected.

It has already been suggested to stop the activity of sponges and bacteria in storage containers Hydrocarbon fuels by treating the water phase of each fuel tank with a to fight and control effective bactericide. From the above it is easy to see that this treatment method in cases where the fuel tanks or fuel cells with a Machine connected is not always feasible. In addition, there is such a control method impracticable and uneconomical when protecting against the bacterial problem in one whole Fuel distribution system is desirable, because of the large number of tanks from which a such a system exists.

The bactericidal compound must be able to be added directly to the kerosene-like hydrocarbon, so that they move with the kerosene from one storage boiler to another and through the engine's fuel system, in which the fuel is burned if necessary, can be transported further. To this This way, an effective control of the bacterial activity can be carried out before using the fuel simply adding the compound to the kerosene prior to its storage can be achieved. To the intended To be able to fulfill the purpose, the bactericidal compound must meet a number of requirements fulfill. Thus the compound must be soluble in kerosene to such an extent that it is soluble for the bacteria lethal concentration in the fuel is reached. In addition, the compound must be highly bactericidal Possess effectiveness. It has been found that some compounds are initially developing prevents bacteria from being effective for a limited time because the Bacteria get used to the connections and generate a certain immunity to them. To a To achieve an effective solution to the above-mentioned problem, such a resistance must of course not occur, but the selected bactericidal compound must kill the bacteria.

In addition, the selected compound must not change the properties of kerosene as a fuel. This requirement is particularly difficult to meet in cases where the fuel is for military Jet aircraft is intended, because of the very high requirements, especially what the Concerning freedom of fuels from precipitation. Fulfilling these requirements is imperative Prerequisite for the usability of the fuel. Furthermore, the bactericidal compound in be sufficient surface active to pass through the hydrocarbon-water interface in the To be able to penetrate the water phase so that it acts on the bacteria where they actually live. To the At the same time, the compound must not have such a large surface activity that it is undesirable Scope of water-in-oil emulsion is formed. Another requirement is that that the compound has balanced properties in terms of extractability, d. i.e. that they cannot be extracted too easily by water, otherwise an undesirably large amount the connection is lost due to the water deposits in the first storage tank of the distribution system, which in turn has the consequence that insufficient amounts of the compound remain in the kerosene to protect against the in the other tanks of the distribution system or in the fuel tank or the machine itself Bacteria to be able to act. At the same time, however, it is also important that certain amounts of Compound extracted by the water deposits in the serially connected tanks, so that a bactericidal concentration can be achieved there.

It has been found that a preservation of water-containing kerosene fuels against bacterial growth while meeting the above criteria in the best possible way by using boron compounds the general formula

R — O — B — O —R

R '

where R is an alkyl radical having 2 to 12 carbon atoms and R 'is hydrogen or R and R may be the same or different in the different positions of the molecule, is achieved, the boron compound the kerosene fuel is added in such an amount that the content of the boron compound in kerosene fuel, based on elemental boron, is at least 0.0004 percent by weight. Boron compounds are preferably used in which R is an alkyl group with 6 to 10 carbon atoms.

The addition of hydrocarbon-soluble boric acid esters in general to hydrocarbon-based fuels is known per se. The additives

followed to reduce the combustion of the fuel in the cylinder by the one operated with it Precipitation occurring on the machine.

The amount of the boron compound to be added to the fuel in the present invention depends on various factors Factors. It has been found that to achieve a complete suppression of bacterial life the water phase must generally have a concentration of the boron compound which is about 0.05 percent by weight of elemental boron. The concentration of the boron compound in kerosene, which is preferred calculated on boron can be calculated on the basis of this number, taking into account the Amount ratio of kerosene to water and the distribution factor of the boron compound between the kerosene and the water phase can be estimated. The latter distribution factor can easily be applied to each Compound by simply adding it to a mixture of kerosene and water Composition, determination of the elemental boron content in both phases and division of the larger number can be obtained by the smaller number. When calculating the amount of water must not only the water in each individual tank can be estimated; the number of water in that must also be estimated Tanks located in the distribution system are taken into account, through which the kerosene is pumped as each tank normally represents a new amount of water to be sterilized. The selection the connection is decisive for how much of the boron compound is in the water phase of the first tank is extracted and how much is left in the kerosene to then switch between the kerosene and the water in to be distributed to the subsequent tanks of the distribution system. In general it can be said that the greater the number of carbon atoms in the alkyl groups of the molecule, the fewer it becomes the boron compound be extractable by water. So is z. B. Tributyl borate more water soluble than trioctyl borate, so that a small amount of this compound in the kerosene of the first is water-containing Tanks is necessary to produce a concentration of 0.05% boron in the water, which is necessary for complete Killing the bacteria ensures. However, since more tributyl borate in the first water deposit, with the If the kerosene comes into contact, is passed over, less boron compound remains in the kerosene for the remaining ones Tanks left in contact with water deposits than in the case of trioctyl borate. It can be seen from this that the choice of boron compound for a particular distribution system depends at least in part on the extent to which an entire tank distribution system has a should be subjected to such treatment.

It should also be taken into account that not every kerosene charge causes the water deposits in every tank full lethal dose of boron must transmit because subsequent, a boron compound according to the invention containing kerosene batches can increase the boron content of the water to a lethal dose. As from the above, the selected active ingredient or the active ingredient mixture to be used and the in the amount of active substance required for the kerosene for each distribution system, taking into account the above Considerations are worked out. However, an amount of active ingredient that is about 0.0004 percent by weight Boron in kerosene is equivalent to being regarded as the smallest amount on first contact produced some obvious effect. The boron compounds are preferred in such amounts added to the kerosene that it has a concentration corresponding to between 0.001 and 0.006 percent by weight of boron in kerosene, especially if two or more tanks are to be treated. The usage quantities greater than 0.01% are not required and are generally economical Reasons not justified either.

ίο A surprising side of the invention lies in the fact that to suppress bacterial activity a much lower boron content in the water phase in the form of the lipophilic organoboron compounds according to the invention is necessary than in the case of previously known ones Treatment methods according to which water-soluble boron compounds remove the water deposits can be added directly to the storage tanks for the kerosene. Because the growth is at the limit phase occurs, the verification of the boron compound from the kerosene in the water phase must necessarily go through this boundary layer. This does not take place if the boron compound is different from At the beginning is located in the water phase, since in this case no transfer from the water phase to the Kerosene phase occurs.

The boron compound can be added directly to the kerosene stock in the necessary quantities will. If desired, a concentrate of the boron compound can be prepared by using an appropriate one Solvent are produced, the concentrate is then added to the kerosene, so the set the desired boron concentration.

The invention will be more easily understood from the description of a test with kerosene stocks in which the actual storage conditions for such kerosene are mimicked via water separation so that the results are correlated with the results obtainable from the real circumstances. This test consists in contacting a kerosene inventory containing trialkyl borate compounds according to the invention with water in a ratio of 100: 1. In carrying out the test, a device consisting of a large sixteen-spoke wheel is used, with openings attached to each other between bottles similar to "1 pint Mason" bottles on each spoke. Each of the pairs of bottles was ^{filled with 400 cm 3} of the kerosene to be tested and 4 cm ^{3 of} water. A polished steel rod was placed in each pair of bottles so that the influence of the bacteria on the corrosion could be observed. The influence of rust formation on the development of the bacteria mimics the circumstances existing under actual storage conditions. The water was taken from an artificial lake that contains bacteria similar to those found in the water at the bottom of the tanks. The wheel is then rotated at three revolutions per minute for 48 hours in order to study the growth of the bacteria, ie each pair of bottles is turned twice per revolution of the wheel so that the contents of the bottles flow back and forth six times per minute during the test. This movement mimics what happens in a storage container when large quantities of kerosene are introduced or discharged, thereby keeping the contents of the tanks in a rolling motion.

At the end of the 48-hour test period, the bacterial density is estimated using the usual plate method. Here, plates are inoculated with a certain amount taken from the soil water and with progressive dilutions of the soil water sample by a power of ten. For this purpose, a 1 cm ^a sample is pipetted off the water layer of the kerosene-water mixture and transferred to a sterile Petri dish. Then about 20 cm ^{3 of} a sterile agar solution are poured into the dish and the contents swirled until completely mixed. The mixture on the plate is then allowed to cool to room temperature, whereupon the agar gels. The plate is then inverted and placed in an incubator held at 37 ° C. After 48 hours of incubation, the bacterial colonies are counted using an illuminated, checkered plate. The result of the test is reported in bacteria per cubic centimeter of the sample. The table below gives the results of this test with kerosene samples which were untreated or treated with a bactericidal compound according to the invention. The kerosene used in this test was a product that meets the requirements of a JP-4 fuel.

attempt Additive bacteria No. corresponds to 0.004 percent by weight boron JC JvUDlK-
centimeter 1 no additive 5,500,000 (Starting kerosene) 2 Triethyl borate 4,000 3 Tripropyl borate 700 4th Tributyl borate 100 35 5 Triamyl borate 25th 6th Trihexyl borate 9 7th Dihexyl borate 5 8th Trioctyl borate 0 9 Tridecyl borate 11 4 ° 10 Tridodecyl borate 130

The above results of this invention show that the compounds at low concentrations have a have very good bactericidal effectiveness. It can be seen from the above results that when the water comes into contact with the boron compounds, io which are the number of carbon atoms in the Alkyl groups is between 6 and 10, the best results will be obtained.

All kerosene products listed in the table have successfully passed the Erdco-Coker test in accordance Subject to the American regulations ASTM-D1660. This test is used to check whether the kerosene fuel is burning properly; he is often considered the most reliable Test viewed to predict actual performance of fuel in turboprop and jet engines. Mixtures 2 through 10 showed no significant differences from Mixture 1 in the amount or nature of that produced Precipitation, from which it can be concluded that the bactericidal substances according to the invention have no harmful effect on the base fuel with respect to the Precipitation rate or in any other respect known to the inventor for use in Has turpoprop and jet engines.

Claims (2)

PATENT CLAIMS: 1. Use of boron compounds of the general formula: R-O-B-O-R R ' wherein R is an alkyl radical having 2 to 12 carbon atoms and R 'is hydrogen or R and R can be the same or different in the different positions of the molecule, for preservation of hydrous kerosene fuels against bacterial growth, with the boron compound is added to the kerosene fuel in such an amount that the content of the boron compound in kerosene fuel, based on elemental boron, at least 0.0004 percent by weight amounts to. 2. Use of boron compounds according to claim 1, characterized in that R is a Is an alkyl group of 6 to 10 carbon atoms. 45 Publications considered:
German interpretative document No. 1 003 985. © 309 747/199 10.63