IT202000015379A1 - Device for the separation through graphene of the hydrocarbons present in a fluid - Google Patents

Description

Description

Field of application

The present invention finds application in the industrial waste water treatment sector and relates to a device capable of effectively separating the hydrocarbons contained in waste water of various nature and origin, through the combined action of graphene and mechanical treatments. The example shown concerns the purification of the internal washing water of the fuel oil tanks, also allowing the extraction of the residual oil.

State of the art

The more and more strict regulations on the protection of water from pollution are framed within an increasingly wide and careful attention to the issues of environmental impact caused by the activities anthropogenic. This aspect, combined with the fact that often the water? a precious but limited asset, gives great importance to a correct and efficient management of the industrial water cycle.

Fuel oil belongs to the category of heavy distillates obtainable from petroleum and is mainly used as a fuel in the production of electricity, in the propulsion of ships, in heating and in the production of process steam necessary for various industrial activities. industrial. Unlike coal, the ash content in fuel oil is ? very modest, generally equal to 0.1%, while that of sulfur is between 2 and 5%. A characteristic of the fuel oil ? instead the presence of water for a quantity? generally equal to 0.1%, derived from transport and storage, and sediments. Such sediments can be of two types, insoluble in benzene and soluble in benzene but insoluble in heptane, the two main hydrocarbons in the oil mixture. The former are formed by coke, unstable hydrocarbons and salts, and their content does not exceed 0.1%; while the latter, whose presence can? up to 7%, are formed by substances with a high molecular weight, brown or black in colour, which also take the name of hard asphalt.

The calorific value of fuel oil varies between 39 and 42 MJ/kg, while its density? at 15 ?C between 0.90 and 0.98, depending on the hydrocarbon composition and the ash, water and sediment content. The denominations widely used in all countries to distinguish the various types of fuel oil, entered into technical use and commercial classification, distinguish the oil into very fluid, light, fluid, thick or extra thick. This denomination? unfortunately misleading, as with the ci? we refer to the viscosity, and not to the density, as the denominations themselves would suggest.

Delicate issue regarding fuel oil? the cleaning of the tanks that contain it, whether they are made of steel or concrete, generally cylindrical in shape. Periodic cleaning? essential for keeping the tank in optimal condition by preventing wear, generally manifested through holes in the walls, causing infiltrations or, much worse, fuel spills outside. Fuel spills, which once reached the ground, infiltrate contaminating the underground aquifers, causing considerable environmental damage. Another problem related to fuel oil tanks? the formation of condensation, due to humidity, inside them. Due to the natural aging of the fuel oil, a phenomenon which also occurs in diesel fuel, solid deposits form which accumulate on the bottom and by binding to the condensation water formed, they generate an oily sludge. This sludge, if sucked in, clogs the burner ducts and the relative filters and nozzles, causing malfunctions in the system, or, over time, forms corrosive residues which increase wear on the tank, as well as toxic for the environment and the groundwater in the event of spillage or loss of the tank itself.

At present, there is not a large number of techniques or procedures to be followed for the cleaning of tanks used to contain fuel oil and other petroleum-derived fuels, such as diesel or petrol.

Washing the environment of a tank can? be articulated in more? phases:

? preliminary washing, in which a team of specialized operators equipped with all the necessary protective devices, opens the manholes of the tank and checks the explosiveness of the tank. o possible presence of toxic fumes in the internal atmosphere;

? suction of pumpable residues;

? crushing of solid residues and sludge and subsequent cleaning of the internal walls by means of flexible lances to direct jets of high pressure fluids (150 bar and higher) on the internal surface of the tank, water-based fluid jets and enzymatic detergents with high degreasing power , capable of breaking the long molecular chains of hydrogen and carbon;

? final washing with hot water, which floats further oily fractions to be extracted, thus creating a mixture of water and oil;

? emptying of the tank by aspiration of the washing waste and consequent disposal of the same in suitable plants;

? opening of the manholes to carry out a forced ventilation that removes the vapors present, thus making the it is possible for personnel to enter the tank for the manual removal, if necessary, of the residues by scraping.

Presentation of the invention

Purpose of the present invention? that of making available an apparatus and a method for the treatment of a fluid composed of two liquid phases which are not miscible with each other, capable of effectively separating these phases, furthermore separating any solid particles present; all that? made possible by the combined action of graphene and mechanical treatments of various kinds.

A particular purpose concerns the internal washing of fuel oil tanks, able to effectively exploit the properties? graphene absorbents. In this invention graphene and mechanical treatments operate in synergy for an optimal separation of the fuel oil present in the washing waste, in order to obtain good quality oil. and reusable.

Another object of the present invention ? that of providing compact equipment that can be easily transported to the place where it is needed and that is self-sufficient from an energy point of view.

Another object of the present invention ? that of providing an economic and completely reliable apparatus for the purification of a fluid. Another object of the present invention ? that of making available an equipment for the purification of a fluid, which allows it to be used in a versatile way even in application fields other than the one shown in the example, easily regulated and adapted to optimize its energy efficiency and capture in every application in which it lends itself to being used. A further object of the following invention ? that of making available an equipment and a method which find application in the removal of oils or hydrocarbons also in streams or aquifers, maintaining the functional diagram and the components studied for the treatment of the tanks and modifying only the modality? of collection of the contaminated water to be treated.

Brief description of the drawings

The technical characteristics of the invention, according to the aforesaid aims, can be clearly seen from the contents of the claims reported below and the advantages of the same will become more evident in the detailed description that follows, made with reference to the attached drawings, which represent some purely exemplary embodiments thereof and non-limiting, in which:

? Fig. 1 illustrates the block diagram showing the various functional components of the apparatus for the treatment of waste water for internal cleaning of tanks, according to the present invention.

Detailed description of a preferred embodiment

With reference to the attached figures? illustrated an example of apparatus for the purification of a fluid, object of the present invention. The example described concerns the treatment of the internal washing water of a fuel oil tank. From what has been described it is clear that the instrument according to the invention achieves the pre-established purposes.

The object of the invention? susceptible to numerous modifications and variations, all falling within the inventive concept expressed in the attached claims. All the details may be replaced by other technically equivalent elements, and the materials may be different according to requirements, without departing from the scope of protection of the present invention.

Even if the object ? been described with particular reference to the accompanying figures, the reference numbers used in the description and in the claims are used to improve understanding of the invention and do not constitute any limitation to the claimed scope of protection.

The equipment is presented as a set of elements forming a real water-mechanical system. This plant takes on compact enough dimensions to be transported via 2 road trailers, thus being able to reach all areas served by the road network.

The washing waste, made up of a mixture of water, fuel oil and solid hydrocarbon residues (basically the sediments of the oil itself), flow into a collection tank located on the bottom of the tank subject to intervention. The mixture of water and graphene, taken directly from the graphene mixing tank, is added to this tank.

What is the mixture? composed of water, oil, solid residues and graphene, it is moved by a pump and sent to the decantation tank, where? temperature controlled through a hot water coil equipped with pressure switch and electro-pneumatic valve. In the example shown, the settling tank has capacity? equal to 4000 litres, while the operating temperature varies between 60 and 80 ?C. In the aforementioned tank, the oil, the hydrocarbon residues and the graphene stratify due to the difference in specific weight; the aggregates of polluting particles having greater weight and dimensions are deposited on the bottom, the molecules of the components more? as light as oil and graphene, they float on the surface (in fact, oil and graphene have a lower specific density than water). The tub ? also equipped with a valve and tap for the occasional drainage of the sludge deposited on the bottom.

The surface patina created? pushed to the weir through a rotating flap, from which it flows into a hopper which unloads into an intermediate tank, with a capacity of 1000 litres, in which the homogenization of the product takes place through a submerged mixer, moved by the M1 engine having equal power at 0.7 kW. In this section, the action of the mixer allows the creation of bonds between the graphene present in solution and the residual hydrocarbons (remember that a known quantity of graphene can absorb, on average, a quantity of hydrocarbons equal to 80 times the its weight). Once the homogenization is completed, the product is sent to a three-phase separator through a submersible pump.

The three-phase separator? a horizontal axis centrifugal separator which, reaching high speeds? of rotation, ? able to separate, thanks to the centrifugal force, the phases that make up the incoming mixture. Specifically, this component? an apparatus designed for the simultaneous separation of three phases, one solid and two liquids, returning the separated components in distinct streams at the outlet. so that does the system work? It is necessary that the three phases satisfy some requirements, for example the two liquid phases have different densities? specific and are not miscible with each other, while the solid phase is present as the pi? heavy of three.

The separator therefore separates? the following stages:

? the solid fraction, made up of graphene which has absorbed the hydrocarbons in the homogenization tank, becoming the lowest phase? heavy among the three, it is recovered by means of a conveyor screw and sent to the graphene mixing tank;

? the light liquid fraction, consisting of fuel oil, is recovered by means of a centripetal pump and sent to the oil recovery tank;

? the heavy liquid fraction, consisting mainly of water and a small part of solid residues of oil and graphene, also recovered by means of the centripetal pump, is sent to the vertical centrifuge.

The optimal separation of the two liquid phases takes place thanks to the regulation system of which ? equipped with a centripetal pump: by modifying the position of the suction section of the pump, the liquid flows out with various diameters, by moving a lever from the outside. Furthermore, a proper regulation of the centripetal pump optimizes the separation performances since ? Is it possible to react quickly to different properties? of incoming products. This component? sized for a fluid flow rate of around 6 m<3>/h, the remaining components of the system are sized so as to respect this value at the inlet of the separator.

The oil accumulated in the recovery tank? to all intents and purposes fuel oil, with hydrocarbon composition that can? vary from the initial one, but that can? still find utility? as fuel. Its properties? they can be improved by mixing it with diesel in proportions suitable for the burner used. Traces of graphene, a non-toxic and non-corrosive material, do not appreciably compromise its use.

The vertical axis centrifuge separates from the heavy liquid fraction (basically water) the micrometric particles (oil and graphene residues) not separated in the previous treatment. These particles are then sent to the graphene mixing tank, while the outgoing clarified water is ? sent in part to the final receptor with suitable characteristics according to the provisions of Legislative Decree 152/06 third part All.5 Tab.3, in part to the graphene mixing tank.

Graphene recovered from the various processes and a percentage of the product as it comes from the storage tank flows into the graphene mixing tank. A part of the incoming clarified water also flows into this tank in order to have a specific composition of water and graphene according to needs. The outgoing compound is sent via a submerged pump P1 to the tank washing water recovery tank, where it is mixed before being sent back to the settling tank. This pump P1 has a power of 1.5 kW, moving a flow rate between 4 and 5 m<3>/h at a pressure of 0.8 bar. The graphene mixing tank ? equipped with a coil, in which hot water flows to control the temperature of the mixture, equipped with a thermostat and electro-pneumatic valve. This tank also has a graphene recovery outlet, which, after a certain number of cycles has reached saturation of its capacity, absorbent, must be recovered and treated in a suitable plant not included in the following invention. The plant? completed by a support section for the treatment line just described, used for the production of the hot water necessary for heating the coils of the two tanks and for washing the tank. These two tanks are kept at a treatment temperature between 60 and 80 ?C. The heat needed? produced by recovering part of the heat possessed by the exhaust gases of the generator set inside the heat exchanger. The power of the generator set? equal to 250 kVA, sufficient to cover the electrical needs of the various components of the system. Does the carrier fluid heated in the exchanger therefore give way? this heat to the hot water tank, maintaining the desired temperature inside this. The water fed to the hot water tank comes from the mains, passing through an intermediate cold water tank. On the other hand, the outgoing hot water, drawn by a P2 pump, with a flow rate of 12 m<3>/h and an operating pressure of 3.2 bar, is divided into three flows, two destined for the two coils of the settling tanks and graphene blending, the third intended for tank washing. 2 P3 high pressure pumps increase the pressure of the third flow to the optimum value for the washing system used. The system described in this example supplies 4 rotating nozzles, 2 for each pump, for washing the tanks with a pressure of 150 bar and a flow rate of 30 l/min.

Do the necessary electrical, safety and control connections and devices complete the system, as well as? valves, regulators, indicators and everything else deemed useful for the proper functioning of the system itself, according to the description just given.

Claims (6)

Claims 1. Device for separating a mixture of hydrocarbons from an incoming fluid comprising, in order of fluid treatment: - A first Recovery Tank, suitable for storing the fluid to be treated in the subsequent equipment; - A second Decantation Tank, with a capacity between 3000 and 5000 litres, equipped with a converging funnel bottom in which the tap for discharging the sludge accumulated on the bottom is located, also equipped internal coil for maintaining, inside it, through the circulation of the heat transfer fluid, i.e. water, the treatment temperature between 60 and 80°C; - A third Homogenization Tank, with a capacity of between 1000 and 2000 litres, fed by the fluid overflowing from the Settling Tank, and equipped with an immersion stirrer inside it, moved by the M1 motor with power between 0.5 and 1 kW; - Three-phase separator, with horizontal axis of the screw and drum type, sized for a total inlet flow rate between 5 and 10 m<3>/h, also equipped with adjustable separating disc, built to separate the three different phases from a three-phase mixture composed of a light liquid phase, a heavy liquid phase and a solid fraction, equipped with three different outlets, each used to collect the flow of a specific phase; - A tank suitable for collecting the flow of the light liquid fraction coming out of the three-phase separator, coinciding with oil, or more? properly mixture of hydrocarbons; - A two-phase separator, used to collect the flow of the heavy liquid fraction, or more? specifically water, of the impeller type on a vertical axis inside the drum, sized for a total inlet flow rate between 5 and 10 m<3>/h, built to separate the two different phases from a two-phase mixture composed of a solid phase and a liquid phase, equipped with two different outlets, each used to collect the flow of a specific phase. 2. Device according to claim 1, characterized in that it uses graphene, stored and supplied through a suitable Graphene Tank, as an absorbent of the hydrocarbons present in the fluid being treated. 3. Device according to claim 1 and claim 2, characterized by the presence of a special Graphene Mixing Tank, equipped with a converging funnel bottom, able to collect the two flows of solid fractions coming from the three-phase separator and from the two-phase separator, also equipped of internal coil for maintaining, inside it, through circulation of the heat transfer fluid, i.e. water of the same type used for the Decantation Tank, the treatment temperature, whose outgoing flow on the bottom, composed of water and graphene, ? conducted, via circulation pump P1, having an operating pressure between 0.5 and 1 bar and a flow rate between 4 and 5 m<3>/h, to the Recovery Tank. 4. Device according to claim 1 and claim 3, characterized in that the flow of the liquid phase, more? properly water, leaving the Two-Phase Separator ? separated into two distinct streams, of which the first is clarified water as the final result of the treatment process, while the second is ? of feed to the Graphene Mixing Tank. 5. Device according to claim 1 and claim 3, equipped with a Hot Water Tank, the inlet of which is? a flow of water taken from the supply network, passing through the Cold Water Tank, and whose outlet is? a flow of hot water, with a flow rate between 10 and 15 m<3>/h, whose temperature is ? between 60 and 80 ?C, drawn by circulation pump P2 at a pressure between 2 and 4 bar, branched in turn into two flows, the first consisting of the heat transfer fluid flowing in the coils used to maintain the treatment temperature in the tank Decantation and Graphene Mixing Tank, the second, moved in turn by 2 P3 high pressure pumps, with operating pressure between 120 and 160 bar and flow rate between 20 and 40 l/min each, directed towards a user that needs washing through nozzles operating at this pressure, like the inside of a tank used for fuel storage. 6. Device according to claim 1 and claim 5, characterized by the presence of a generator set, with PRP (Prime Power), according to the meaning expressed by the ISO 8528 standard, between 200 and 300 kVA, fueled by diesel, used for the production of the electric energy necessary for the operation of the plant, whose exhaust gases feed a heat exchanger in which circulated a heat transfer fluid which subsequently heats the water in the Hot Water Tank.