EP2981763A2

EP2981763A2 - Device and method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil

Info

Publication number: EP2981763A2
Application number: EP14722753.2A
Authority: EP
Inventors: Enrico Fumagalli
Original assignee: Advanced Financial Services SA
Current assignee: Advanced Financial Services SA
Priority date: 2013-04-05
Filing date: 2014-04-02
Publication date: 2016-02-10
Also published as: WO2014162281A3; WO2014162281A2; ITVR20130082A1

Abstract

A device for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil comprises a main body (2) forming a main duct (3) comprising a first end (4) connectable to first feeding means (6) for feeding pressurised fuel oil and a second end (5), and a secondary body (8) forming a secondary duct (9) comprising an infeed section (10) connectable to second feeding means (13) for feeding pressurised water, and an outfeed section (11) connected to an intermediate portion (12) of the main duct (3); first nebulising means (14) are mounted in the main duct (3) upstream of the intermediate portion (12), and second nebulising means (15) are mounted in the secondary duct (9); it also comprises heating means (33) operatively associated at least with the main body (2) for heating it. A method implemented by the device (1) is also claimed.

Description

DEVICE AND METHOD FOR MAKING EMULSIONS OF WATER IN FUEL OIL OR IN A MIXTURE CONTAINING MAINLY FUEL OIL

* * *

DESCRIPTION

This invention relates to a device and a method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil.

Fuel oil is a mixture of hydrocarbons obtainable as a waste product of petroleum distillation processes. Although broadly speaking the term fuel oil may also refer to any product of petroleum processing (even diesel), in the context of this invention it identifies only those residual products of petroleum processing which are intermediate between more valuable products and residual products with lower value (therefore excluding finer products such as diesel and less fine products such as sludge or HFO).

To more accurately identify them, it may be considered that the fuel oils referred to by this invention are those having viscosity of between 3° Engler and 24° Engler if measured at 50°C.

This invention in any case applies both to these pure residual products and to their dilutions with other substances. In fact, at industrial level, fuel oil is usually obtained by diluting a high viscosity residue of petroleum distillation with a petroleum distillate, called flux oil.

In general the residue available depends on the technical structure of the plants of the refineries in which it is produced. For example, in refineries without conversion plants the residue used is that from atmospheric distillation, whilst in more complex refineries the residue may be of various types, for example, from vacuum distillation.

The flux oils used may be products of first distillation such as kerosene or diesel fuels obtained from cracking plants.

Regarding the classification of fuel oils, at present in the sector there are many different ones based on various regulations in force.

For example, based on viscosity the fuel oil may be defined as: - light if it has viscosity of between 3° and 5° Engler at 50 °C;

- heavy if it has viscosity greater than 12° Engler at 50 °C.

Based on the sulphur content, light fuel oil can be defined as:

- LSFO, with sulphur content < 1 % in weight; and

- ULSFO, with sulphur content < 0.3% in weight;

whilst heavy fuel oil can be defined as:

- HSFO, with sulphur content < 3% in weight;

- LSFO, with sulphur content < 1 % in weight; and

- ULSFO, with sulphur content < 0.3% in weight.

Since it is a petroleum processing waste product, enormous quantities of fuel oil are produced around the world each year. Although it is theoretically a waste product, since fuel oil as such still has excellent calorific value, it is widely used. At present, in particular, fuel oil is mainly used in stationary combustion for the production of steam for industrial uses or for generating electricity. Another very important use is that in large engines for propelling ships or for producing electricity in small power stations.

The main problem linked to the use of fuel oil, as with the combustion of any hydrocarbon, is however the possible resulting pollution.

The combustion of hydrocarbons in general, and of fuel oils in particular, in fact produces significant emissions both of NO_x and of CO and of PM (particulate matter).

For years now it has been known that to attempt to overcome this disadvantage it is possible to feed burners not with a pure hydrocarbon, but rather with a hydrocarbon in which water in emulsion has been inserted. This technology allows not just a reduction in polluting combustion residues, but also an increase in fuel efficiency and a therefore a reduction in greenhouse gas emissions.

The main mechanism through which the water of the burning emulsion carries out its beneficial action is practically instantaneous evaporation, manifesting as proper micro-explosions of the droplets of water in emulsion. Since the water droplets are encompassed in larger drops of hydrocarbon previously atomised in a combustion chamber, their evaporation causes further atomisation of the individual drops of hydrocarbon (secondary atomisation). Therefore, following this secondary atomisation a large number of extremely small fuel particles is obtained, with a considerable increase in the surface area in contact with the air supporting combustion.

In the combustion of emulsions if the phenomenon of micro-explosions is substantial, that is to say, if most of the drops from primary atomisation are involved in secondary atomisation, there is a significant change in the shape and structure of the flame due to the reduction in the reaction time necessary for combustion (thanks to the fact that the drops to be burned are smaller). Moreover, in this way, the risk of unburnt particles is also reduced. As already indicated, the use of emulsions with water in the hydrocarbons sector has been known for many years. In particular, emulsions of water and diesel are known and used. In contrast, the use of emulsions of water and fuel oil is not currently particularly widespread, since it has not yet been possible to define solutions which allow sufficiently homogeneous and stable emulsions to be obtained.

However, definition of such solutions is very desirable. In fact, the possible benefits of use of emulsified fuel oil would include:

- increased combustion efficiency due to the reduced rate of unburnt particles, thanks to the lower burn-out times as a result of the small diameters of the drops of fuel oil obtainable thanks to secondary atomisation;

- lower solid particulate matter emissions, again as a result of improved combustion caused by secondary atomisation; and

- the possibility of reducing excess air supporting combustion, which in contrast is essential in the combustion of only fuel oil in order to achieve acceptable combustion efficiency.

Thanks to the reduction in excess air, the following are achieved: - improved combustion efficiency thanks to the reduction in the combustion temperature and therefore in the heat dispersed into the environment with the fumes;

- a noticeable reduction in the production of SO₃ (up to 80%) due to the lower concentration of O2 in the fumes, as well as a reduction in NO_x.

Furthermore, the combustion of emulsified oil compared with combustion of pure fuel oil allows a reduction both in dirtying of heat exchange surfaces and in corrosive phenomena. In fact, first, thanks to the improved combustion efficiency the fuel oil burns completely, resulting in a reduced deposit of unburnt particles on heat exchange surfaces. Second, thanks to the use of less excess air, there is a fall in the amount of V₂O₅ which can form in favour of vanadium oxides with a lower oxidation number which are less prone to adhere to surfaces. Moreover, thanks to the fact that the emulsions of water in fuel oil produce shorter flames, the molten ashes, before striking the wall of the pipes, have more time to cool to a state in which their surface is firm or in any case is no longer able to adhere to the surfaces with which it comes into contact. Moreover, the shorter flame reduces or eliminates the risk that the flame may make contact with the surfaces of the pipes, and consequently there is a reduction both in the formation of hard corrosive salts in the high temperature zones, and in localised heating of the pipes. Finally, the reduced presence of oxygen and the consequent reduction in SO₃ causes less formation of H₂SO₄, and therefore a reduced corrosive effect on the cold zones of the boilers.

The direct practical consequence of these benefits are:

- reduced need for routine and extraordinary maintenance and consequent greater plant operating availability;

- possibility of drastically reducing blowing cycles;

- possibility of reducing or eliminating installation and operating costs relating to systems for reducing NO_x and solid particulate matter;

- improved performance of electrostatic filters (or other dust removal systems), or reduction-elimination of their installation and operating costs; - complete elimination of pre-flame additives and drastic reduction of MgO based treatment.

Therefore, it seems obvious how the use of emulsions of water in fuel oil is absolutely desirable.

As is known, in general an emulsion is a mixture of two immiscible fluids, in which one of the two is present in the form of more or less large drops within the other. The fluid in dispersed drops is defined the dispersed phase, whilst the other is the continuous phase. Since the emulsion substantially adopts the chemical - physical properties of the continuous phase, in the context of hydrocarbons in general and of fuel oils in particular, we refer only to those emulsions in which the continuous phase is the hydrocarbon (also called the oily phase) since they have the properties of the hydrocarbon and not of the water.

There are various prior art apparatuses for the production of emulsions of water in fuel oil, such as those described in the patents/patent applications WO 2005/037961 , EP 958853, DE 102010056345, EP 1183094, US 2004/220284, WO 83/01210, DE 19917753, JP 59200113, US 4335737 and JP 2011064440.

However, the prior art solutions are not without disadvantages.

In particular, prior art apparatuses and methods are not able to create emulsions which are at the same time stable over time and uniform enough, and in which the droplets of water are small enough.

In fact, over time, if the mixing of the two phases is not adequate (and in particular if the drops of water are too big), the two phases tend to separate into the stable states of the dispersed and continuous phases. According to the prior art, in an attempt to keep an emulsion with oily phase stable as time passes, surfactants are normally used, which are added to the water. In fact, the presence of surfactants in the droplets of water tends to reduce the interface tension between the water and the fuel oil, substantially preventing the droplets of water from aggregating and coalescing. However, even this solution has proved ineffective where homogenisation of the emulsion was not adequate.

Second, in order to guarantee constant performance in the combustion chamber, the emulsion must uniformly involve all of the individual drops of fuel which are atomised in the combustion chamber. In contrast, with the current technologies, the drops of water which are successfully incorporated in the fuel oil may be relatively too big to guarantee sufficient uniformity of combustion. In fact, both drops of fuel without water (which therefore have all of the problems of fuel oil which is not in an emulsion) and drops of water without fuel oil can enter the combustion chamber.

Moreover, the insufficient uniformity of emulsion tends to also cause reduced stability of the emulsion itself as time passes.

In this context the technical purpose which forms the basis of this invention is to provide a device and a method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil which overcomes the above- mentioned disadvantages.

In particular, the technical purpose of this invention is to provide a device and a method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil, which allow the obtainment of emulsions which are more homogeneous, with drops of water that are on average smaller, and consequently more stable than those obtainable with the current technologies.

The technical purpose and the aims indicated are substantially fulfilled by a device and a method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil, in accordance with what is described in the appended claims.

Further features and the advantages of this invention are more apparent in the detailed description, with reference to the accompanying drawings which illustrate several preferred, non-limiting embodiments of a device and a method for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil, in which:

- Figure 1 is a schematic view partly in cross-section of a device for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil;

- Figure 2 is a schematic view of an enlarged detail of the device of Figure 1 ; and

- Figure 3 is a schematic view of an apparatus comprising a device according to this invention.

With reference to the accompanying drawings the numeral 1 denotes in its entirety a device for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil according to this invention.

As shown in Figure 1 , the device 1 comprises first a main containment body 2 forming a main duct 3 inside it. The main duct 3 extends between a first end 4 and a second end 5. During operation, the first end 4 is connectable to first feeding means 6 for feeding pressurised fuel oil or a pressurised mixture containing mainly fuel oil, whilst the second end 5 allows the emulsion to be dispensed. Advantageously, the second end 5 of the main duct 3 is formed by a nebuliser nozzle 7.

In the embodiment illustrated, the main body 2 consists of a plurality of rigid metal parts which are connected to one another. In other embodiments it is possible both that the main body 2 consists of a single body such as a tube, and that the main body 2 is flexible or semi-rigid.

The device 1 also comprises a secondary containment body 8 forming a secondary duct 9 inside it which extends from an infeed section 10 to an outfeed section 11 . The outfeed section 11 is connected to the main duct 3 at an intermediate portion 12 of the main duct, in such a way that the secondary duct 9 leads into the main duct 3. During operation, the infeed section 10 is connectable to second feeding means 1 3 for feeding at least pressurised water (with the addition of an additive if necessary).

Advantageously, the secondary duct 9 converges with the main duct 3 according to a direction of incidence which is substantially perpendicular, in such a way that the two flows collide with each other perpendicularly.

In the embodiment illustrated, the secondary body 8 also consists of a plurality of rigid metal parts which are connected to one another. However, in other embodiments it is possible both that it too consists of a single body such as a tube, and that the secondary body 8 is flexible or semi-rigid.

According to this invention, the device 1 comprises first nebulising means 14 and second nebulising means 15.

The first nebulising means 14 are mounted in the main duct 3 upstream of the intermediate portion 12, and are designed to nebulise, during operation, the flow of fuel oil or of a mixture containing mainly fuel oil (hereinafter also referred to as the first flow).

In turn, the second nebulising means 15 are mounted in the secondary duct 9 close to where it opens into the main duct 3, and are designed to nebulise, during operation, a flow of water or of water mixed with an emulsifying additive (hereinafter also referred to as the second flow).

In the preferred embodiment the first nebulising means 14 comprise a first tube 16 positioned in the main duct 3 immediately upstream of the intermediate portion 12 and substantially aligned with a direction of extension of the main duct 3 itself. The first tube 16 comprises a first upstream end 17 and a first downstream end 18.

The first upstream end 17 is connected to the inner part of the main duct 3 for receiving its entire flow. In the preferred embodiment that is achieved by means of a funnel-shaped wall 19 which connects the inner surface of the main duct 3 to the first upstream end 17. In contrast, the first downstream end 18 is closed, and the first tube 16 also comprises a first lateral wall 20 with micro-holes made in it which is distanced from the inner surface of the main duct 3. Therefore, between the first tube 16 and the inner surface of the main duct 3 there is an annular space in which the first flow can be nebulised. Similarly, according to the preferred embodiment, the second nebulising means 15 comprise a second tube 21 positioned in the secondary duct 9 close to the outfeed section 11 and substantially aligned with a direction of extension of the secondary duct 9 itself. The second tube 21 comprises a second upstream end 22 and a second downstream end 23. The second upstream end 22 is connected to the inner part of the secondary duct 9 for receiving its entire flow. In the preferred embodiment that is achieved by means of a wall 24 which connects the inner surface of the secondary duct 9 to the second upstream end 22. In contrast, the second downstream end 23 is closed, and the second tube 21 comprises a second lateral wall 25 with micro-holes made in it which is distanced from the inner surface of the secondary duct 9. Between the second tube 21 and the inner surface of the secondary duct 9 there is again an annular space in which the second flow can be nebulised.

In the preferred embodiment, the first nebulising means 14 also comprise first turbulence creating means 26 mounted between the first end 4 and the intermediate portion 12, and the second nebulising means 15 comprise second turbulence creating means 27 mounted in the secondary duct 9 (advantageously along practically the entire secondary duct 9 from the infeed section 10 to the second upstream end 22).

In the embodiment illustrated, the first turbulence creating means 26 comprise a plurality of bars 28 positioned transversally to the extension of the main duct 3 at different angles to one another, and which are positioned one after another along the extension of the main duct 3, so as to form a sort of labyrinth for the first flow.

The embodiment illustrated also shows how the first nebulising means 14 advantageously also comprise, immediately downstream of the first end 4, at least one pierced plate 29 positioned transversally to the main duct 3 for intercepting the first flow during operation. Said pierced plate 29 has a concave shape on the side facing towards the first end 4 in such a way that the jets coming out of each hole have a different direction and there is at least one component of motion perpendicular to the main direction of extension of the main duct 3 (a direction coinciding with the direction of feed of the flow as a whole inside the main duct 3).

As regards the second turbulence creating means 27, in the preferred embodiment, they comprise a rotary shaft 30 (only schematically illustrated in Figure 1 ), mounted in the secondary duct, extending substantially parallel with the secondary duct itself. The shaft 30 is advantageously pneumatically operated.

As shown in Figure 2, which illustrates an enlarged stretch of the secondary duct 9 and of the shaft 30 installed in it, mounted on the shaft 30 there is blading 31 comprising blades of different shapes, sizes and with different directions of extension. Preferably, the shaft 30 comprises a plurality of identical modules 32 which are coupled one after another, one of which is shown in Figure 2.

According to this invention, the device 1 comprises heating means 33 operatively associated at least with the main body 2, but advantageously also with the secondary body 8, for heating them. In the preferred embodiment the heating means 33 comprise a plurality of electric heating elements 34 which in the embodiment illustrated are inserted in suitable housings made in the main body 2.

Advantageously, downstream of the intermediate portion 12, the cross- section of the main duct 3 is gradually reduced until it reaches the nebuliser nozzle 7. As is explained in more detail below, this stretch with decreasing cross-section allows the flow to be recompacted, giving the actual emulsion. Moreover, advantageously, at the stretch with decreasing cross-section the device 1 also comprises stop means 35 against which the mixture of the two nebulised flows can collide for improved recompacting. In the preferred embodiment, the stop means 35 comprise a plurality of projecting elements 36 mounted inside the main duct 3, advantageously angled towards the first end 4.

Figure 3 schematically illustrates an apparatus which can use the device 1 according to this invention.

The apparatus comprises first feeding means 6 for feeding the pressurised fuel oil or mixture which are connected to the first end 4 of the main duct 3, second feeding means 13 for feeding at least pressurised water which are connected to the infeed section 10 of the secondary duct 9, and an emulsion collecting tank 43 connected downstream of the second end 5 of the main duct 3.

Advantageously, both the first feeding means 6 and the second feeding means 13 comprise a source of the respective liquid which may be either a storage unit 37, 38 as shown in Figure 3, or a continuous feeding circuit (in particular for the water), and a respective pump 39, 40.

Depending on requirements, the apparatus may also comprise third feeding means 41 for feeding at least one emulsifying additive operatively connected to the second feeding means 13 for adding the emulsifying additive to the water fed towards the infeed section 10. The third feeding means 41 also comprise a source of the respective liquid (such as a storage unit 42), and if necessary a pump (not illustrated in the accompanying drawings).

As already indicated, this invention also relates to a method for making an emulsion of water in fuel oil or in a mixture containing mainly fuel oil, which can be implemented in the apparatus just described.

Said method comprises first the operating steps of generating a first pressurised liquid flow of fuel oil or of a mixture containing mainly fuel oil, and of generating a second pressurised liquid flow of at least water (if necessary with the emulsifying additive added to it). Advantageously, in the preferred embodiments, the second flow comprises only water if the quantity by weight of second flow injected into the first flow per unit of time is less than or equal to 12% of the total weight of the emulsion obtained, whilst the second flow comprises water and at least one emulsifying additive if the quantity by weight of second flow injected into the first flow per unit of time is greater than 15% of the total weight of the emulsion obtained. Within the range between 12% and 15% the decision whether or not to use only water or water with the additive added to it must be made on each occasion based on requirements.

Preferably, the first flow is generated at a pressure of between 20 and 30 bar, whilst the second flow is generated at a pressure of between 22 and 32 bar.

The method then comprises in parallel the operating steps of creating turbulences in the first flow and creating turbulences in the second flow. It then comprises nebulising the two turbulent flows and injecting the nebulised second flow into the nebulised first flow so as to mix them.

Regarding the nebulising steps, both the first flow and the second flow are advantageously nebulised in a direction transversal to the respective direction of overall feed (where that refers to the macroscopic direction of feed of the flow as a whole, not that of the individual molecules), for also imparting a component of vortical motion to them. In the preferred embodiment the first flow is nebulised using a first pierced wall (such as the first lateral wall 20) in which the holes have a diameter of between 0.05 mm and 0.4 mm, whilst the second flow is nebulised using a second pierced wall (such as the second lateral wall 25) in which the holes have a diameter of between 0.05 mm and 0.2 mm.

Regarding the step of mixing the two flows, advantageously, as in the device 1 in Figure 1 , it occurs according to a direction of incidence of the second flow on the first, which is transversal to the overall direction of feed of the first flow.

Finally, the method comprises recompacting the mixture of the two flows to actually create the emulsion.

In the preferred embodiment, after the recompacting step, the method according to this invention comprises a step of nebulising the recompacted emulsion (by means of the nebuliser nozzle 7 in Figure 1 ).

Moreover, advantageously, during the recompacting step on one hand the mixture of the two nebulised flows is made to at least partly strike the stop means 35, and on the other hand the feed speed of the mixture of the two flows is increased (for example, thanks to the decreasing cross-section in the device 1 described above).

Advantageously, the entire process occurs while keeping at least the first flow, but advantageously also the second flow, at a temperature of between 50°C and 70°C.

It should be noticed that operation of the device 1 described above corresponds to a possible way of implementing the method according to this invention.

In fact, the first flow first passes through the pierced plate 29 which divides it into a plurality of jets with different orientation in space, already creating first turbulence phenomena which are then accentuated by the transversal bars 28. The first flow, with vortical motion, then reaches the pierced first tube 16, from which it comes out nebulised in radial directions to reach the mixing zone in a nebulised form and with vortical motion.

Parallel with that, the second flow travels along the secondary duct 9 where it is agitated by the rotary shaft 30 (which may be activated at speeds of around 300 - 500 rpm) which makes its motion turbulent. Then it reaches the pierced second tube 21 from which it comes out nebulised in radial directions for reaching the mixing zone in a nebulised form and with vortical motion. In the mixing zone it makes impact with the first flow according to a direction of incidence which is substantially transversal to the motion of the first flow.

At that point the mixture of the two nebulised flows enters the stretch with decreasing cross-section where it collides with the stop means 35 and is compacted to create a single liquid flow which, once it has reached the nebuliser nozzle 7, is further nebulised at atmospheric pressure. After that the emulsion is ready, homogeneous and stable.

It should be noticed that what is described above relative to the device 1 must also be considered valid relative to the method (if applicable) and vice versa.

Supporting the good results achieved by this invention, below are the results of several tests which were carried out at the Norwegian Institute Norsk Energi of Oslo.

In particular, tests were run on both the stability of an emulsion of only water in fuel oil with a water content of 1 5% of the total weight, and of the combustion parameters of said emulsion which were compared with those of pure fuel oil.

The stability tests, carried out using the "Marcusson" method, based on centrifugation of the emulsion, did not reveal any separation of the water after centrifugation.

The combustion tests were carried out both on the pure fuel oil and on the emulsified fuel oil with 1 5% water.

Table 1 shows the reference standard method adopted for the measurements, the typical measurement uncertainty and the measuring range.

Parameter Reference standard Typical Measuring measured method measurement range

uncertainty of the

method

NOx NS-EN 14792 ± 1 -2% <10000 ppm

CO NS-EN 15058 ± 2% 0-740 mg/m³ o₂ NS-EN 14789 ± 0.05% 0-25% total volume

Moisture NS-EN 13284-1 ± 10-15% 0-100% total volume

Flow rate NS-EN13284-1 ± 20% 4-50 m/s

Temperature NS-EN 13284-1 ± 2% 0-1200°C of fumes Table 1 - References adopted for measurements Table 2 shows the data of the various pollutants measured at the different burner operating speeds while feeding only fuel oil. Each measurement is expressed both in ppm, and in mg/Nim³. Moreover, for each measurement a value is also shown relating to an oxygen content in the fumes equal to 3%. The values in italics are those which do not meet current legal requirements concerning emission levels.

As can be seen, the levels are not acceptable for NO_x or for CO.

Table 2 - Measurement carried out on unemulsified fuel oil for a period of one week Table 3 shows the corresponding quantities of oxygen, carbon dioxide and moisture detected.

Table 3 - Measurement carried out on unemulsified fuel oil for a period of one week. Percentage values relative to the total volume of the fumes

Table 4 shows the data of the various pollutants measured at the different burner operating speeds while feeding emulsified fuel oil with only water at 1 5%. Each measurement is expressed both in ppm, and in mg/Nim³. Moreover, for each measurement a value is also shown relating to an oxygen content in the fumes equal to 3%. It should be noticed that each measurement was repeated both with the burner up to speed (stable) and with the burner being adjusted.

The values in bold type are those which do not meet current legal requirements concerning emission levels in the case of combustion of only fuel oil. As can be seen, in the case of the emulsion those values went down in an extremely significant way, until they were within current legal requirements.

Parameter Burner operating Emissions as dry gas under measured speed standardised conditions (0°C; 1.013 bar)

Measured Measured Relating to an [ppm] [mg/Nm³] oxygen content in the fumes of 3%

[mg/Nm³]

Minimum 24 49 68

Adjustment Maximum 27 81 88

Average 22 70 87

NOx

Minimum 21 48 62

Stable Maximum 24 85 87

Average 27 65 76

Minimum 2 47 67

Adjustment Maximum 7 48 51

Average 28 67 69

CO

Minimum 0.2 0.3 0.3

Stable Maximum 2.1 2.7 3.4

Average 1.0 1.3 1.5 Minimum 9 26 33.

Adjustment Maximum 12 35 53

Average 11 32 41 so₂

Minimum 6 16 20

Stable Maximum 12 34 39

Average 11 30 35

Table 4 - Measurement carried out on emulsified fuel oil with 15% water (relative to the total weight) for a period of one week

Finally, table 5 shows the corresponding quantities by volume detected for oxygen, carbon dioxide, nitrous oxide and moisture.

Table 5 - Measurement carried out on emulsified fuel oil with 15% water (relative to the total weight) for a period of one week. Percentage values relative to the total volume of the fumes

Therefore, the tests carried out demonstrated how an emulsion with 15% of only water in fuel oil made using a device 1 according to this invention on one hand is extremely stable, and on the other hand guarantees performance during combustion which is significantly better than unemulsified fuel oil.

This invention therefore brings important advantages.

In fact, thanks to this invention it was possible to define a device and a method able to make emulsions of water (pure or with the addition of an additive) in fuel oil or a mixture containing mainly fuel oil, which are stable over time, extremely uniform, thanks to the smaller size of the drops of water, and able to guarantee extremely low levels of pollutant emissions. Finally, it should be noticed that this invention is relatively easy to produce and that even the cost linked to implementing the invention is not very high. The invention described above may be modified and adapted in several ways without thereby departing from the scope of the inventive concept. Moreover, all details of the invention may be substituted with other technically equivalent elements and the materials used, as well as the shapes and dimensions of the various components, may vary according to requirements.

Claims

1. A device for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil, comprising:

a main containment body (2) forming a main duct (3) comprising a first end (4) connectable during operation to first feeding means (6) for feeding pressurised fuel oil or a pressurised mixture containing mainly fuel oil, and a second end (5) for dispensing the emulsion;

a secondary containment body (8) forming a secondary duct (9) comprising an infeed section (10) connectable during operation to second feeding means (13) for feeding at least pressurised water, and an outfeed section (11 ) connected to the main duct (3) at an intermediate portion (12) of the main duct;

first nebulising means (14) mounted in the main duct (3) upstream of the intermediate portion (12), for nebulising during operation a flow of fuel oil or of a mixture containing mainly fuel oil, the first nebulising means (14) comprising a first pierced wall with holes having a diameter of between 0.05 mm and 0.4 mm;

second nebulising means (15) mounted in the secondary duct (9) for nebulising during operation a flow of at least water, the second nebulising means (15) comprising a second pierced wall with holes having a diameter of between 0.05 mm and 0.2 mm; and

heating means (33) operatively associated at least with the main body (2) for heating it.

2. The device according to claim 1 , characterised in that the main duct (3) downstream of the intermediate portion (12) has a decreasing section.

3. The device according to claim 1 or 2, characterised in that the decreasing section of the main duct (3) ends at the second end (5) for dispensing the emulsion.

4. The device according to any one of the preceding claims, characterised in that it also comprises a nebuliser nozzle (7) which forms the second end (5) of the main duct (3).

5. The device according to any one of the preceding claims, characterised in that the secondary duct (9) converges with the main duct (3) according to a direction of incidence which is substantially perpendicular.

6. The device according to any one of the preceding claims, characterised in that the first nebulising means (14) comprise a first tube (16) positioned in the main duct (3) immediately upstream of the intermediate portion (12) and substantially aligned with a direction of extension of the main duct (3) itself, the first tube (16) comprising a first upstream end (17) connected to the inner part of the main duct (3) for receiving its entire flow, a closed first downstream end (18), and a first lateral wall (20) with micro-holes made in it which is distanced from an inner surface of the main duct (3), the first lateral wall (20) constituting the first pierced wall.

7. The device according to any one of the preceding claims, characterised in that the second nebulising means (15) comprise a second tube (21 ) positioned in the secondary duct (9) close to the outfeed section (11 ) and substantially aligned with a direction of extension of the secondary duct (9) itself, the second tube (21 ) comprising a second upstream end (22) connected to the secondary duct (9) for receiving its entire flow, a closed second downstream end (23), and a second lateral wall (25) with micro- holes made in it which is distanced from an inner surface of the secondary duct (9), the second lateral wall (25) constituting the second pierced wall.

8. The device according to any one of the preceding claims, characterised in that the first nebulising means (14) comprise first turbulence creating means (26) mounted between the first end (4) and the intermediate portion (12).

9. The device according to claim8, characterised in that the first turbulence creating means (26) comprise a plurality of bars (28) positioned one after another along the extension of the main duct (3) and positioned transversally to said extension at different angles to one another.

10. The device according to any one of the preceding claims, characterised in that the first nebulising means (14) comprise, immediately downstream of the first end (4), at least one pierced plate (29) positioned transversally to the main duct (3) for intercepting the flow in it during operation.

11. The device according to any one of the preceding claims, characterised in that the second nebulising means (15) comprise second turbulence creating means (27) mounted in the secondary duct (9).

12 The device according to claim 11 , characterised in that the second turbulence creating means (27) comprise a rotary shaft (30), mounted in the second duct, extending substantially parallel with the second duct itself, and provided with blading (31 ).

13. The device according to claim 12, characterised in that the shaft (30) comprises a plurality of identical modules (32) which are coupled one after another.

14. The device according to any one of the preceding claims, characterised in that it also comprises stop means (35) for the flow mounted in the main duct (3) downstream of the intermediate portion (12).

15. The device according to claim 14, characterised in that the stop means (35) comprise a plurality of projecting elements (36) mounted inside the main duct (3).

16. An apparatus for making emulsions of water in fuel oil or in a mixture containing mainly fuel oil, comprising first feeding means (6) for feeding the pressurised fuel oil or mixture, second feeding means (13) for feeding at least pressurised water, an emulsion collecting tank (43), and a device (1 ) according to any one of the preceding claims, the first feeding means (6) being connected to the first end (4), the tank (43) to the second end (5) and the second feeding means (13) to the infeed section (10).

17. The apparatus according to claim 16, characterised in that it also comprises third feeding means (41 ) for feeding at least one emulsifying additive operatively connected to the second feeding means (13) for adding the emulsifying additive to the water fed towards the infeed section (10).

18. A method for making an emulsion of water in fuel oil or in a mixture containing mainly fuel oil, comprising the operating steps of:

generating a first pressurised liquid flow of fuel oil or of a mixture containing mainly fuel oil at a pressure of between 20 and 30 bar;

generating a second pressurised liquid flow of at least pressurised water at a pressure of between 22 and 32 bar;

creating turbulence in the first flow and then nebulising it using a first pierced wall in which the holes have a diameter of between 0.05 mm and 0.4 mm;

creating turbulence in the second flow and then nebulising it using a second pierced wall in which the holes have a diameter of between 0.05 mm and 0.2 mm; and

injecting the nebulised second flow into the nebulised first flow according to a direction of incidence which is transversal to a direction of overall feed of the first flow, for mixing the two flows;

recompacting the mixture of the two flows to create the emulsion.

19. The method according to claim 18, characterised in that all of the steps are carried out while keeping at least the first flow, and advantageously also the second flow, at a temperature of between 50°C and 70°C.

20. The method according to claim 18 or 19, characterised in that both the first flow and the second flow are nebulised in a direction transversal to the respective direction of overall feed, thereby imparting a vortical motion to them.

21. The method according to any one of the claims from 18 to20, characterised in that after the recompacting step, the method comprises a step of nebulising the emulsion.

22. The method according to any one of the claims from 18 to21 characterised in that the second flow comprises only water if the quantity by weight of second flow injected into the first flow per unit of time is less than or equal to 12% of the total weight of the emulsion obtained, or in that the second flow comprises water and at least one emulsifying additive if the quantity by weight of second flow injected into the first flow per unit of time is greater than 15% of the total weight of the emulsion obtained.

23. The method according to any one of the claims from 18 to 22 characterised in that after the injecting step the feed speed of the mixture of the two flows is increased.

24. The method according to any one of the claims from 18 to 23, characterised in that during said recompacting step the mixture of the two nebulised flows is at least partly made to strike stop means (35).