WO2015150971A1

WO2015150971A1 - Emulsifying additive for forming emulsions of water in heavy fuel oil (hfo)

Info

Publication number: WO2015150971A1
Application number: PCT/IB2015/052158
Authority: WO
Inventors: Enrico Fumagalli
Original assignee: FUBER Ltd
Current assignee: FUBER Ltd
Priority date: 2014-04-03
Filing date: 2015-03-24
Publication date: 2015-10-08
Anticipated expiration: 2016-10-03

Abstract

An emulsifying additive for forming emulsions of water in heavy fuel oil, characterised in that it comprises, by weight, at least: Ethereal Ethoxylate from 25% to 30%; - Ethylene Oxide from 0.1 % to 0.9%; Sorbitan Monostearate from 27% to 35%; Magnesium Sulphate from 1 % to 2.5%; Polyvinyl acetate from 2.0% to 5%; one out of Sorbitan Stearate, Sorbitan Olivate and Sorbitan Monooleate from 18% to 24%; Ethylhexyl Stearate from 0.9% to 3.2%. and optionally at least one out of: C21 Dicarboxylic acid from 1.1 % to 2.2% Polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether from 1.8 to 5.8%.

Description

EMULSIFYING ADDITIVE FOR FORMING EMULSIONS OF WATER IN HEAVY FUEL OIL (HFO)

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DESCRIPTION

This invention relates to an emulsifying additive for forming emulsions of water in pure heavy fuel oil (HFO).

Heavy fuel oil (HFO) is a mixture of hydrocarbons obtainable as an end waste product of petroleum distillation processes. In particular, in the context of this invention, the intention is to identify mainly those residual products of petroleum processing which are commonly used as marine fuel or fuel for large thermoelectric power plants. In the former context, the heavy fuel oil is also referred to as marine sludge.

However, to more accurately identify them, it may be considered that the heavy fuel oils for which this invention is intended are those having viscosity of between 24° Engler and 50° Engler if measured at 50°C.

As already indicated, this invention in any case applies both to these pure residual products and to any mixtures containing them.

In general the residue available after petroleum processing 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.

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 the sulphur content, fluid heavy fuel oil (HFO) may be defined as:

- LS, with sulphur content < 1 % by weight; and

- ULS, with sulphur content < 0.3% by weight;

whilst dense heavy fuel oil may be defined as:

- HS, with sulphur content < 3% by weight; - LS, with sulphur content < 1 % by weight; and

- ULS, with sulphur content < 0.3% by weight.

Since it is a waste product of practically any petroleum processing, enormous quantities of heavy fuel oil (HFO) are produced around the world each year. Although it is theoretically a waste product, since heavy fuel oil (HFO) as such still has excellent calorific value, it is now widely used as a fuel. At present, in particular, as already indicated, heavy fuel oil (HFO) is mainly used for marine propulsion, especially for large ships.

Therefore, it shall be understood that this invention is aimed mainly at a marine fuel which is heavy fuel oil (HFO) based.

The main problem linked to the use of heavy fuel oil (HFO), even more than the combustion of any other hydrocarbon, is however the possible resulting pollution.

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

With regard to this, it should be noticed for example that many states ban the use of marine sludge as a fuel when ships are less than a predetermined safe distance from the coast. In fact, the fumes deriving from combustion of the marine sludge are highly polluting. That makes it necessary for ships to have a second fuel available (usually diesel oil) to be used close to the coast, with a consequent significant disadvantage in economic terms, given that the cost of diesel oil is considerably higher than that of marine sludge. Alternatively, it would be possible to use SCR filters, but their extremely high cost has so far discouraged people from using them.

Moreover, for years now it has been known that to attempt to overcome the pollution produced by burning hydrocarbons it is possible to feed burners not with a pure hydrocarbon, but rather with a hydrocarbon in which water in emulsion has been inserted.

In fact, this technology allows not just a reduction in polluting combustion residues, but also an increase in fuel efficiency and 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 heavy fuel oil (HFO) is not currently known, since it has not yet been possible to define solutions which allow sufficiently homogeneous and stable emulsions to be obtained.

Therefore, definition of such solutions is very desirable. In fact, the possible benefits of use of emulsified heavy fuel oil (HFO) 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 heavy fuel oil (HFO) 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 heavy fuel oil (HFO) 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 heavy fuel oil (HFO) compared with combustion of pure heavy fuel oil (HFO) allows a reduction both in dirtying of surfaces and in corrosive phenomena. In fact, first, thanks to the improved combustion efficiency the heavy fuel oil (HFO) burns completely, resulting in a reduced deposit of unburnt particles on 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 heavy fuel oil (HFO) produce shorter flames, any 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 overheating 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.

The direct practical consequence of these benefits are:

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

- 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;

- possibility of easier re-use of the marine fuel which seeps from the engines and is collected together with water in the bilge below

Therefore, it seems obvious how the use of emulsions of water in heavy fuel oil (HFO) 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 heavy 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 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 2012/167451 , US 6296676, CN 1240815, US 2007/113938, US 6068670, WO 2011 /115501 and US 2003/024852.

Despite the many attempts made up to now, there has not been any effective definition of additives able first to make stable over time an emulsion of water in heavy fuel oil (HFO), especially 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 heavy fuel oil (HFO), first is kept for long periods of time in the tanks of ships, and, second, 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 heavy fuel oil which overcomes the above-mentioned disadvantages.

In particular, the technical purpose of this invention is to provide an emulsifying additive for forming emulsions of water in heavy 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 heavy fuel oil 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 a preferred, non-limiting embodiment of an emulsifying additive for forming emulsions of water in heavy fuel oil 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):

Ethereal Ethoxylate from 25% to 30%;

Ethylene Oxide from 0.1 % to 0.9%;

- Sorbitan Monostearate from 27% to 35%;

Magnesium Sulphate from 1 % to 2.5%;

Polyvinyl acetate from 2.0% to 5%;

one out of Sorbitan Stearate, Sorbitan Olivate and Sorbitan Monooleate from 18% to 24%; and

- Ethylhexyl Stearate from 0.9% to 3.2%.

The additive may also comprise at least one out of:

C21 Dicarboxylic acid from 1 .1 % to 2.2%; and

Polyethylene glycol p-(1 ,1 ,3,3-tetramethylbutyl)-phenyl ether) from 1 .8 to 5.8%, in particular the one commercially known as Triton X-100.

It must be noted that Sorbitan Monostearate and Sorbitan Stearate are distinct components; then, in the context of the present invention, when Sorbitan Stearate is used, it must always be intended to be in addition to Sorbitan Monostearate.

In the preferred embodiments, the Ethereal Ethoxylate is obtained by making the ethylene oxide (C2H2O) react with an alcohol which may be either Coco- Glucoside or Lanolin.

However, in a particularly preferred embodiment of this invention, the additive comprises the following components in the following quantities:

Coco-Glucoside or Lanolin based Ethereal Ethoxylate from 28.3% to 28.7%; Ethylene Oxide from 0.58% to 0.62%;

Sorbitan Monostearate from 34.2% to 34.6%;

Magnesium sulphate from 1 .95% to 2.05%;

Polyvinyl acetate from 4.4% to 4.6%;

- Sorbitan Stearate from 21 .8% to 22.2%;

Ethylhexyl Stearate from 2.9% to 3.1 %; and

Polyethylene glycol p-(1 ,1 ,3,3-tetramethylbutyl)-phenyl ether from 4.9 to 5.1 %.

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 heavy fuel oil (HFO) which uses the additive described above. Said emulsion advantageously comprises, by weight relative to the total: from 4 to 40% water;

from 0.3 to 1 .2% of an additive made according to the present invention; - and heavy fuel oil (HFO) 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. But advantageously it may even be used with excellent results for quantities of water much higher than 25% (even up to 30-40%).

Supporting the good results achieved by this invention, below are the results of several tests which Intertek (Schweiz) AG carried out.

In particular, tests were run on the stability of an emulsion in heavy fuel oil (HFO) of water and additive according to this invention, with a water content of 25% of the total weight and an additive content of 0.5%. The stability tests, carried out using the "UNICHIM MU 1548" method, based on centrifugation of the emulsion and applied to 3 samples, did not reveal any separation of the water after centrifugation and showed the presence of a 0.5 imL sediment after centrifugation.

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, as required in the marine propulsion sector) of emulsions of water in heavy fuel oil (HFO) even with 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 heavy fuel oil, characterised in that it comprises, by weight, at least:

Ethereal Ethoxylate from 25% to 30%;

- Ethylene Oxide from 0.1 % to 0.9%;

Magnesium Sulphate from 1 % to 2.5%;

Polyvinyl acetate from 2.0% to 5%;

one out of Sorbitan Stearate, Sorbitan Olivate and Sorbitan Monooleate from 18% to 24%;

- Sorbitan Monostearate from 27% to 35%, the Sorbitan Monostearate being distinct from said Sorbitan Stearate; and

Ethylhexyl Stearate from 0.9% to 3.2%.

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

- C21 Dicarboxylic acid from 1 .1 % to 2.2%

Polyethylene glycol p-(1 ,1 ,3,3-tetramethylbutyl)-phenyl ether from 1 .8 to 5.8%.

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 the Ethereal Ethoxylate is Coco Glucoside- or Lanolin- based.

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

- Ethereal Ethoxylate from 28.3% to 28.7%;

Ethylene Oxide from 0.58% to 0.62%;

Sorbitan Monostearate from 34.2% to 34.6%;

Magnesium Sulphate from 1 .95% to 2.05%;

Polyvinyl acetate from 4.4% to 4.6%;

- Sorbitan Stearate from 21 .8% to 22.2%; Ethylhexyl Stearate from 2.9% to 3.1 %; and

6. An emulsion of water in heavy fuel oil (HFO), 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 0.3 to 1 .2 emulsifying additive;

and heavy fuel oil (HFO) to make it up to 100%.

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

9. The emulsion according to claim 8, comprising, by weight, at least 25% water.