AGENT FOR AVOIDING AND/OR DESTROYING MICROBIAL GROWTH IN A STORE FOR A LIQUID HYDROCARBON, METHOD FOR AVOIDING AND/OR DESTROYING MICROBIAL GROWTH IN A STORE FOR A LIQUID HYDROCARBON, STORE FOR A LIQUID HYDROCARBON

Abstract

A separation agent for avoiding and/or destroying microbial growth in a store for a liquid hydrocarbon is provided wherein an interface between a phase of a liquid hydrocarbon and a phase of water can be reduced. The agent has a density which is higher than the density of a liquid hydrocarbon and lower than the density of water. By using the agent, simple, economical, efficient and long-lasting avoidance and/or destruction of microbial growth in a store for a liquid hydrocarbon is ensured. The avoidance and/or destruction includes inhibition of the increase in the microorganisms already present in the store and/or the killing thereof and a high quality of the respective liquid hydrocarbon is ensured. A method for avoiding and/or destroying microbial growth in a store for a liquid hydrocarbon, and a store for a liquid hydrocarbon which is suitable for the avoidance and/or destruction of microbial growth are also disclosed.

Claims

1. Means for the avoidance and/or elimination of microbial growth in a storage (2) for a liquid hydrocarbon (3), characterized in that the means is a separation means with which an interface (5) between a phase of a liquid hydrocarbon (3) and a phase of water (4) can be reduced, and the means comprises a density which is greater than the density of the liquid hydrocarbon (3) and which is lower than the density of the water (4).

2. Means according to claim 1, characterized in that the means comprises a non-stick material and/or a biocide and/or a biostatic.

3. Means according to claim 1, characterized in that the means is a solid (1a) and/or a liquid (1b).

4. Means according to claim 2, characterized in that the biocide and/or the biostatic can be released in a controlled manner.

5. Means according to claim 2, characterized in that the biocide is a microbiocide and that the biostatic is a microbiostatic.

6. Means according to claim 2, characterized in that the biocide and/or the biostatic contains silver and/or a silver salt.

7. Means according to claim 2, characterized in that the biocide and/or the biostatic are present as particles.

8. A method for the avoidance and/or elimination of microbial growth in a storage (2) for a liquid hydrocarbon (3), comprising the following steps: introduction of a means as a separation means, which has a greater density than a liquid hydrocarbon (3) and which has a lower density than water (4), and reduction of an interface (5) between a phase (3a) of the liquid hydrocarbon (3) and a water phase (4a).

9. Method according to claim 8, characterized in that the means comprises a non-stick materials and/or a biocide and/or a biostatic.

10. A storage (2) for a liquid hydrocarbon (3), characterized in that a means is arranged as a separation means between a phase of a liquid hydrocarbon (3a) and a water phase (4a), whereby an interface (5) between a phase (3a) of the liquid hydrocarbon (3) and a water phase (4a) is reduced.

11. Storage (2) for a liquid hydrocarbon (3) according to claim 10, characterized in that the means comprises a non-stick materials and/or a biocide and/or a biostatic.

Description

[0044] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of embodiments with reference to the drawings. In the drawings:

[0045] FIG. 1 shows a conventional storage for a liquid hydrocarbon,

[0046] FIG. 2 shows a storage for a liquid hydrocarbon inside which is arranged a means in the form of multiple solid bodies located at a distance from each other, and

[0047] FIG. 3 shows a storage for a liquid hydrocarbon inside which is arranged a means in the form of a liquid.

[0048] FIG. 1 shows a conventional hydrocarbon storage 2. The top region of conventional hydrocarbon storage 2 contains a phase 3a of a liquid hydrocarbon 3, which is in contact with a water phase 4a via an interface 5. The one or more hydrocarbons 3 serve as substrates or nutrients for microorganisms or microbes, particularly for bacteria, yeasts, fungi and algae. The water 4 which is unavoidably present in the combustion agents, fuel or propellants represents habitat for microorganisms. It is particularly problematic that contamination with water 4 may occur anywhere throughout the entire supply chain from the refinery to the intermediate storage facility to the fuel tank or the heating oil tank, for example when the storage or tank is filled or vented. The biomass growth caused by the microorganisms leads to many different kinds of damage, for example filtering and separation problems, particularly the clogging of filters and associated machine malfunctions, engine corrosion, storage damage, damage to injection pumps and nozzles, up to and including their failure, broken metal parts, eroded turbine blades and general corrosion. The microbial corrosion of diesel tanks and the associated diesel engine malfunctions caused by microorganisms is called “diesel bug”.

[0049] FIG. 2 shows a hydrocarbon storage 2 according to an embodiment of the present invention. It may be a fixed location or mobile storage 2 for a wide variety of liquid hydrocarbons 3, which are used in the refinery, marine, aviation and automotive industries for example. Combustion agents, fuel or propellants such as diesel, biodiesel, heating oil, gasoline, kerosene, biokerosene or naphtha may be stored and/or transported therein. Unlike the hydrocarbon storage shown in FIG. 1, storage 2 is characterised in that a means 1 in the form of several solid bodies 1a spaced apart from each other is arranged on the interface or contact surface 5 between phase 3a of liquid hydrocarbon 3 and the water phase 4a. Advantageously, this has the effect of reducing interface 5. Means I thus functions as a separation means.

[0050] With the hydrocarbon storage 2 shown in FIG. 2, prevention and/or destruction of microbial growth, particularly in the presence of bacteria, yeasts, fungi and algae, is ensured. At the same time, such prevention and/or destruction may entail inhibiting the proliferation of existing microorganisms and/or killing them. The arrangement of the solid bodies 1a in the area of the interface between hydrocarbon phase 3a and water phase 4a has the effect of reducing or—depending on the configuration of solid bodies 1a—even entirely eliminating interface 5 or the contact surface between the two phases 3a, 4a. Consequently, the microorganisms existing in hydrocarbon storage 2 are deprived of the environment that supports their subsistence, since microorganisms need the hydrocarbon 3 as a source of nutrition and energy and water 4 as habitat. As a logical consequence, the microorganisms already present may be killed or at least their proliferation may be strongly inhibited.

[0051] It is particularly advantageous that means 1 or solid 1 establishes itself in the area where the problem of microorganism loading in the hydrocarbon 3 arises—i.e. in the area of interface 5—solely by virtue of its density, which is adjustable in advance according to the application case. The density of the means may be adjusted specifically according to the application case, that is to say depending on the hydrocarbon 3 or hydrocarbon mixture that is stored or to be stored in the hydrocarbon storage. This adaptability of the means 1 or solid 1a makes it very versatile.

[0052] Solid 1a is preferably configured as a float, e.g., as a solid or hollow body comprising one or more materials which is not soluble either in the liquid hydrocarbon 3 or in the water 4. In order to reduce interface 5 as far as possible, a plurality of spherical solid bodies 1a arranged are used as shown in FIG. 2. A defined spacing of solid bodies 1a with respect to each other may be achieved for example if solid bodies 1a are disposed in a net-like matrix or mesh product consisting of textile or metal strands or are arranged and fixed releasably along at least one textile or metal strand wherein the distance between solid bodies 1a is predefinable. This also makes it easy to replace one or more solid bodies 1a.

[0053] Alternatively or additionally, one or more solid bodies 1a may be used that have a certain longitudinal or areal dimension. Depending on the number and/or configuration of floating bodies 1a, it may be possible to eliminate interface 5 entirely.

[0054] Solid 1a may comprise a biocide and/or a biostatic, either in the form of a doping substance or a coating. If the radius of action of the biocide and/or biostatic is sufficiently definable and sufficiently large, the number of solid bodies 1a required can be calculated. When using multiple solid bodies 1a, particular attention must always be paid to ensure sufficient reduction of interface 5.

[0055] Alternatively or additionally to a biocide and/or biostatic, solid 1a may contain a non-stick material such as polytetrafluoroethylene (PTFE, Teflon®) or a perfluoroalkoxy polymer (PFA, Teflon® PFA). Depending on the required density and cost, solid 1a may consist partially or entirely of the non-stick material, or only the surface thereof may be coated therewith. It may be for for example a centrosymmetrical solid or hollow body having two identical hemispheres, such as a ball, wherein only the surface of one hemisphere has the non-stick substance. The non-stick substance lends a further “beading” effect to the solid 1a which is positioned in the region of the interface 5 due to its density. This further strengthens the effect of the solid 1a—that of reducing the interface or contact surface 5 between the two phases. Because the microorganisms, which favour the water phase 4a as habitat are prevented still more effectively from reaching the nutrients in the hydrocarbon phase 3a that are essential for their survival by the “beading” effect of the surface of solid 1a.

[0056] Regardless of whether solid 1a consists of the non-stick material or is only coated therewith, the surface thereof may include a biocide and/or a biostatic. In this case, the non-stick material may be doped with biocide and/or biostatic, for example. The presence of a biocide may have the effect of killing microorganisms that exist on the water/hydrocarbon interface 5. In the presence of a biostatic, the proliferation of such microorganisms is inhibited. There are also biocides which function as biostatics at the same time, and vice versa. In order to improve the long-term effect, a dopant can be selected which comprises various biocides and/or biostatics. In this case it is advantageous if the various biocides and/or biostatics are in varying degrees of interaction with the surface of solid 1a. Then, the biocides and/or biostatics are may be released successively over a long period. Thus, the long-term effect may be improved. Alternatively, the surface of one embodiment of solid 1a which has no non-stick material may be coated or doped with a biocide and/or biostatic.

[0057] As shown in FIG. 3, a liquid may also be used as means 1 instead of a solid 1a. Liquid 1b is preferably immiscible or only very poorly miscible with liquid hydrocarbon 3 and preferably immiscible or only very poorly miscible with water 4. Liquid 1b thus acts as a separation means between the water 4 and the liquid hydrocarbon 3.

[0058] In one embodiment, liquid 1b contains a biocide and/or a biostatic. The concentration of the biocide and/or biostatic in liquid 1b should be chosen such that it can ensure efficient destruction of existing microorganisms and/or at least inhibit the propagation of microorganisms. In this way, a long-term effect is ensured.

[0059] Alternatively, the fluid 1b may itself be the biocide and/or biostatic, in which case liquid 1b should be immiscible or only poorly miscible with the hydrocarbon 3 and with the water 4.

[0060] Regardless of the type of liquid 1b chosen, the volume of the liquid 1b is preferably chosen in such a ratio to the determinable volumes of hydrocarbon 3 and water 4 that a miscibility gap is created both between the liquid 1b and the hydrocarbon 3 and between the liquid 1b and the water 4. This prevents the formation of a homogeneous phase consisting of hydrocarbon 4 and liquid 1b or of water 4 and liquid 1b and thus ensures separation of the hydrocarbon phase 3a and the water phase 4a. A long-term effect can be ensured by the choice of the layer thickness of the liquid 1b, because a reservoir of the biocide and/or biostatic is provided depending on layer thickness. The thicker the layer of liquid 1b, the greater the distance between the hydrocarbon phase 3a and the water phase 4a. Then, mixing of the two phases 3a, 4a can be largely prevented even if vibration occurs.

[0061] It is also possible to use both a solid 1a and a liquid 1b as the means. And a plurality of different solid bodies 1a and/or several different liquids 1b may be provided in the same embodiment.

[0062] If a solid 1a and/or a liquid 1b is provided which contains/contain a biocide and/or biostatic, it is advantageous if the biocide and/or biostatic is dispensable in controlled manner. The biocide and/or biostatic may be dispersed or dissolved in liquid 1b. The microorganisms are exposed to the biocide and/or biostatic at least at the interface between the water phase 4a and the liquid phase 1b or the surface of the solid 1a. In this way, the microorganisms may be killed and/or the proliferation thereof may be inhibited. The controllable release of the biocide and/or biostatic is particularly advantageous for long-term action, particularly if the biocide and/or biostatic is discharged relatively slowly and as needed. In this way, the microorganisms may be prevented from developing resistances to the active substance of the biocide and/or biostatic. Additionally, the need for large quantities of the generally expensive biocides and/or biostatics required may be reduced. Thus, this embodiment of the hydrocarbon storage 2 provides a solution that is particularly advantageous from both a financial and an environmental point of view. Controllable delivery may be achieved for example by furnishing the active particles of the biocide and/or biostatic with a casing which is more readily soluble in water than the active ingredient particles themselves. Alternatively or additionally, a mixture of various biocides and/or biostatics which exhibit different degrees of interaction with the means 1 may be used.

[0063] In a further variant of the hydrocarbon storage 2 shown in FIG. 2, the biocide and/or biostatic contain(s) silver and/or a silver salt. The use of silver and/or silver salts is particularly efficient because they have both bactericidal and bacteriostatic properties. The bactericidal and bacteriostatic effects are satisfactory both with elemental silver and with silver in ionic form.

[0064] The biocide and/or biostatic may be present as particles. This ensures that a relatively large surface area of the biocide and/or biostatic is available, which enhances the efficiency of means 1. Preferably, nanoparticles and/or nanofibres are used. In this way, the surface is enlarged further, thus increasing the efficiency of the means 1. The nanofibres may be present for example as monofilaments and/or as a lattice-like structures and/or filaments. The particles and fibres may have diameters between 10 nm and 2000 nm, preferably between 100 nm and 1000 nm, more preferably between 150 nm and 500 nm, and very particularly preferably between 200 nm and 300 nm.

[0065] Overall, hydrocarbon storage 2 serves to prevent microbial fouling particularly in the presence of bacteria, yeasts, fungi and algae cheaply, efficiently and sustainably. A long-term solution is provided that preserves both the environment and resources while maintaining the quality of the respective liquid hydrocarbon, particularly a combustible medium, fuel or propellant. The hydrocarbon storage 2 can also be handled easily and safely. It is no longer necessary to invest significant time and effort in cleaning the hydrocarbon storage 2 after every use, because the formation of unwanted biomass is significantly reduced or inhibited in advance by the presence of means 1. Thus, the consequential costs for cleaning, maintaining and repairing the hydrocarbon storage 2 are also reduced by the use of the means 1 to treat an existing condition and/or as a preventative measure.

[0066] The invention is not limited to any one of the embodiments described above, it can be modified in many ways.

[0067] All of the features and advantages described in the claims, the description and the drawings including design details, spatial configurations and procedural steps, may be essential to the invention both individually and in a wide range of combinations.

LIST OF REFERENCE SIGNS

[0068] 1 Means

[0069] 1a Solid

[0070] 1b Liquid

[0071] 2 Storage for a liquid hydrocarbon/hydrocarbon store

[0072] 3 Liquid hydrocarbon

[0073] 3a Phase of a liquid hydrocarbon

[0074] 4 Water

[0075] 4a Phase of water

[0076] 5 Interface