WO2014162280A1

WO2014162280A1 - Emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil and method for its production

Info

Publication number: WO2014162280A1
Application number: PCT/IB2014/060383
Authority: WO
Inventors: Enrico Fumagalli
Original assignee: FUBER Ltd
Current assignee: FUBER Ltd
Priority date: 2013-04-05
Filing date: 2014-04-02
Publication date: 2014-10-09
Anticipated expiration: 2015-10-05
Also published as: ITVR20130081A1

Abstract

An emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, comprising Sorbitan Stearate, Squalane, Magnesium Sulfate, Hydrogenated Polydecene, C12-15 Alkyl Benzoate, Cyclopentasiloxane, Polyglyceryl-3 dioelate, Sodium Chloride, Ethylhexyl Stearate, Water, Caustic Soda, and Sorbitan Monooleate. Hydrogenated Castor Oil and/ Sorbitan Olivate may also be present. An emulsion containing the emulsifying additive and a method for producing the emulsifying additive are also claimed.

Description

EMULSIFYING ADDITIVE FOR FORMING EMULSIONS OF WATER IN PURE FUEL OIL OR IN MIXTURES CONTAINING MAINLY FUEL OIL AND METHOD FOR ITS PRODUCTION

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DESCRIPTION

This invention relates to an emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, and a method for its production.

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 incorporated 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.

The main problem of all emulsions is that by their very nature they tend to be intrinsically unstable. In fact, over time, 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 the dispersed phase tends to reduce the interface tension between the dispersed phase and the continuous phase, substantially preventing the droplets of the dispersed phase from aggregating and coalescing.

Some examples of additives which can be used to try to increase the stability of emulsions of water in fuel oil are described in the patents/patent applications: GB 974042, US 201 2/167451 , US 6296676, CN 124081 5, US 2007/11 3938, US 6068670, WO 20111\ 1 5501 and US 2003/024852. Despite the many attempts made up to now, there has not been any definition of additives able first to make stable over time an emulsion of water in fuel oil or in a mixture containing mainly fuel oil even in the presence of large quantities of water. And secondly it has not been possible to effectively reduce the environmental impact of combustion (paradoxically some additives which improve stability may in fact have a negative environmental impact, themselves resulting in the formation of pollutants). In addition, the emulsifying additive must be able to guarantee stability not just during storage of the emulsion, but up until the moment of combustion. In fact, it should be remembered that a fuel oil, just before it is actually burned, is subjected in engines and burners to critical temperature and pressure conditions which must not put a strain on the stability of the emulsion.

In this context the technical purpose which forms the basis of this invention is to provide an emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil which overcomes the above- mentioned disadvantages, as well as defining a method for its production. In particular, the technical purpose of this invention is to provide an emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, which at the same time guarantees optimum stability of the emulsion and slashing of the pollutants produced by combustion, in particular in the case of emulsions which contain a large quantity of water.

The technical purpose and the aims indicated are substantially fulfilled by an emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, and by a method for its production, in accordance with what is described in the appended claims.

Further features and the advantages of this invention are more apparent from the detailed description of several preferred, non-limiting embodiments of an emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, and a method for its production described below.

In accordance with the most general embodiment of this invention, the emulsifying additive comprises as a percentage of the total weight, at least the following components within the ranges indicated (the English definition, if different is shown in brackets):

- Sorbitan Stearate from 4.0 to 9.0%

- Squalane from 3.0 to 8.0%

Magnesium Sulfate from 0.1 to 0.6%

- Hydrogenated polydecene from 2.0 to 5.0%

- C12-15 Alkyl Benzoate from 0.5 to 1 .1 %;

Cyclopentasiloxane from 1 .5 to 3.0%;

Polyglyceryl-3 dioelate from 0.8 to 1 .4%;

- Sodium Chloride from 0.6 to 1 .2%;

- Ethylhexyl Stearate from 0.6 to 1 .2%;

- Water from 10 to 30%;

- Caustic Soda from 0.8 to 1 .8%; and

Sorbitan Monooleate to make it up to 100%.

The additive may also comprise at least one out of:

- Hydrogenated Castor Oil from 1 .1 to 2.1 %; and

- Sorbitan Olivate from 0.8 to 1 .8%.

However, in the preferred embodiment each of the components listed above is present in the following quantities:

Sorbitan Stearate from 5.0 to 7.5%;

- Squalane from 4 to 6.5%;

Magnesium Sulfate from 0.2 to 0.5%;

Hydrogenated polydecene from 3.0 to 3.5%

- C12-15 Alkyl Benzoate from 0.7 to 0.9%;

Cyclopentasiloxane from 2 to 2.5%;

- Polyglyceryl-3 dioelate from 1 to 1 .1 %; Sodium Chloride from 0.8 to 0.9%;

Ethylhexyl Stearate from 0.8 to 0.9%;

- Water from 15 to 20%;

Caustic Soda from 1 .1 to 1 .5%;

- Hydrogenated Castor Oil from 1 .3 to 1 .9%; and

Sorbitan Olivate from 1 to 1 .5%.

As can be seen, these are known substances, but the innovative aspect of this invention is the special recipe defined.

Advantageously, although it is possible to also use further components in the additive, in the preferred embodiments it comprises only non-nitrogenous components in such a way that it cannot itself be a source of the formation of ΝΟχ.

Furthermore, the subject matter of this invention also includes an emulsion of water in fuel oil or in a mixture of fuel oil, which uses the additive described above.

Said emulsion advantageously comprises, by weight relative to the total: from 4 to 40% water;

from 0.4 to 1 .1 % of an additive made according to any one of the preceding claims;

- and fuel oil or a mixture containing mainly fuel oil to make it up to 100%.

However, preferably, the additive according to this invention is used for quantities of water equal to at least 12% of the total weight of the emulsion.

Finally, the subject matter of this invention also includes a method for the production of an additive of the type described above.

Said method substantially comprises obtaining the additive described above by means of the following operating steps of:

creating a first mixture by mixing together Sorbitan Stearate, Squalane,

Magnesium Sulfate, Hydrogenated Polydecene, C12-15 Alkyl Benzoate,

Cyclopentasiloxane, Polyglyceryl-3 dioelate, Sodium Chloride and Ethylhexyl Stearate; separately creating a second mixture by mixing the Caustic Soda with the Water; and

mixing the first mixture with the second mixture and with the Sorbitan Monooleate to obtain the additive.

All of the substances used are used in quantities such that, in the finished products, the percentages indicated above are complied with.

If the additive also comprises Hydrogenated Castor Oil and/or Sorbitan Olivate, these are also added to the first mixture.

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 in fuel oil of water and additive according to this invention with a water content of 22% of the total weight and an additive content of 1 %, as well as the combustion parameters of said emulsion which were compared with those of pure fuel oil.

The stability tests, carried out using a 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 22% water and 1 % emulsifying additive.

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

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.

measured VALUE VALUE

o₂ 4.5 3.0 7.4

co₂ 11.8 9.7 13.0

Moisture 11.5 11.5 11.5

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 it with fuel oil emulsified with water at 22% and the additive according to this invention at 1 %. 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.

Minimum 1 44 63

Adjustment Maximum 5 45 49

Average 23 62 65

CO

Minimum 0.2 0.3 0.3

Stable Maximum 1.6 1.9 3.1

Average 0.9 1.4 1.5

Minimum 9 27 34

Adjustment Maximum 11 33 50

Average 14 37 49 so₂

Minimum 8 17 21

Stable Maximum 11 33 37

Average 13 31 33

Table 4 - Measurement carried out on emulsified fuel oil with 22% water (relative to the total weight) and 1 % additive 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 22% water (relative to the total weight) and 1 % additive for a period of one week. Percentage values relative to the total volume of the fumes

This invention brings important advantages.

In fact, thanks to this invention it was possible to define an emulsifying additive which on one hand allows the achievement of extremely high stability (even for months) of emulsions of water in fuel oil or in mixtures containing mainly fuel oil even with relatively large quantities of water. On the other hand it allows the creation of emulsions which are rich enough in water to cause an increase in combustion efficiency and a reduction in polluting 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. An emulsifying additive for forming emulsions of water in pure fuel oil or in mixtures containing mainly fuel oil, characterised in that it comprises, by weight, at least:

- Sorbitan Stearate from 4.0 to 9.0%;

Squalane from 3.0 to 8.0%;

Magnesium Sulfate from 0.1 to 0.6%;

Hydrogenated polydecene from 2.0 to 5.0%

- C12-15 Alkyl Benzoate from 0.5 to 1 .1 %;

- Cyclopentasiloxane from 1 .5 to 3.0%;

Polyglyceryl-3 dioelate from 0.8 to 1 .4%;

Sodium Chloride from 0.6 to 1 .2%;

Ethylhexyl Stearate from 0.6 to 1 .2%;

- Water from 10 to 30%;

- Caustic Soda from 0.8 to 1 .8%;

and Sorbitan Monooleate to make it up to 100%.

2. The emulsifying additive according to claim 1 , characterised in that it also comprises, by weight, at least one out of:

Hydrogenated Castor Oil from 1 .1 to 2.1 %; and

- Sorbitan Olivate from 0.8 to 1 .8%.

3. The emulsifying additive according to claim 1 or 2, characterised in that it comprises exclusively non-nitrogenous components.

4. The emulsifying additive according to any one of the preceding claims, characterised in that it comprises, by weight, at least:

- Sorbitan Stearate from 5.0 to 7.5%;

Squalane from 4 to 6.5%;

Magnesium Sulfate from 0.2 to 0.5%;

Hydrogenated polydecene from 3.0 to 3.5%

- C12-15 Alkyl Benzoate from 0.7 to 0.9%;

- Cyclopentasiloxane from 2 to 2.5%; Polyglyceryl-3 dioelate from 1 to 1 .1 %;

Sodium Chloride from 0.8 to 0.9%;

Ethylhexyl Stearate from 0.8 to 0.9%;

- Water from 15 to 20%;

- Caustic Soda from 1 .1 to 1 .5%;

and Sorbitan Monooleate to make it up to 100%.

5. The emulsifying additive according to claim 4, characterised in that it also comprises, by weight, at least one out of:

Hydrogenated Castor Oil from 1 .3 to 1 .9%; and

- Sorbitan Olivate from 1 to 1 .5%.

6. An emulsion of water in fuel oil or in a mixture containing mainly fuel oil, comprising an emulsifying additive according to any one of the preceding claims.

7. The emulsion according to claim 6, comprising, by weight, at least:

- from 4 to 40% water;

from 0.4 to 1 .1 % emulsifying additive;

and fuel oil or a mixture containing mainly fuel oil to make it up to 100%.

8. The emulsion according to claim 6 or 7, comprising, by weight, at least 12% water.

9. A method for making an additive according to any one of the preceding claims from 1 to 6, comprising the operating steps of:

creating a first mixture by mixing together Sorbitan Stearate, Squalane, Magnesium Sulfate, Hydrogenated Polydecene, C12-15 Alkyl Benzoate, Cyclopentasiloxane, Polyglyceryl-3 dioelate, Sodium Chloride and Ethylhexyl Stearate;

separately creating a second mixture by mixing the Caustic Soda with the Water; and

mixing the first mixture with the second mixture and with the Sorbitan Monooleate.

10. The method according to claim 9, for making an additive according to claim 2 or 5, characterised in that during the step of creating the first mixture at least one out of Hydrogenated Castor Oil and Sorbitan Olivate is also mixed in.