GB2106134A - Stabilizers for oil-water mixtures - Google Patents

Abstract

A stabilizing agent which produces stable fuel oil-water mixtures for use as fuels with consequent fuel savings comprises: a combustible emulsifier 6 to 11.5 parts by weight ferrocene 4 to 9 parts by weight bensoic acid 0 to 12 parts by weight and also, either magnesium (as an oil-soluble magnesium salt) 4.5 to 9.2 parts by weight and an anionic surfactant 1.4 to 3 parts by weight or long chain fatty phosphate esters 25-45 parts by weight in an oil-based liquid medium. u

Description

SPECIFICATION Stabilizers for oil-water mixtures This invention relates to stable oil-water mixtures for use as fuel; to a stabilizing agent for use in the formation of such mixtures; and to a method of forming such mixtures.

In the current energy crisis, it is generally considered essentiai to conserve fossil fuels as much as possible by greater economy in usage. The remaining supplies have only a limited life and are not replaceable. In the field of heavy fuel oil, e.g. oil for use in domestic and industrial heating boilers, it has been proposed to mix a proportion of water with the oil in order to extend it and thus to conserve oil supplies. The water may act purely as a diluent, or may actually benefit the combustion by taking part in the chemical reactions which occur at high temperatures. In either event, less fuel is burnt for the production of the same amount of heat and thus oil supplies are conserved. However, the problem is to provide a stable dispersion of water in oil which can be burnt as a fuel without adversely affecting the burner.The oil-water mixture must form a relatively stable emulsion which does not immediately separate before it has a chance to be burnt and which should preferably be able to be stored for some time. Many additives which might stabilize such a mixture are deleterous to burner installations and would cause corrosion or blockage.

We have now found a particular mixture of compounds which can be used in combination with water to render the water almost totally miscible with fuel oil to provide a stable dispersion which can be used as a fuel and which comprises up to 30 or 40, or even 50% by volume of water.

According to the invention there is provided a stabilizing agent for an oil-water mixture comprising the following components: A combustible emulsifier 6 to 1 1.5 parts by weight; Ferrocene 4 to 9 parts by weight; Benzoic acid 0 to 12 parts by weight; and also, either Magnesium (as an oil-soluble magnesium salt) 4.5 to 9.2 parts by weight; and An anionic surfactant 1.4 to 3 parts by weight; or long chain fatty phosphate esters in an oil-based medium 25-45 parts by weight; The emulsifier should be a combustible emulsifier which is oil-soluble and which is non-toxic. The emulsifier is preferably a mixed glyceride, that is to say a mixture of mono, di- and triglycerides of fatty acids with 1 2 to 20 carbon atoms in the acid moiety.The glycerides may be based on one or more fatty acids and are conveniently based on a number of fatty acids derived from a naturally occurring triglyceride. The glyceride mixture preferably has as low an iodine value as possible and is preferably hydrogenated.

The long chain fatty phosphate esters are preferably present in an amount of 30-35 parts by weight and may generally comprise vegetable oil phosphate esters, e.g. castor oil phosphate esters.

They are conveniently used in the form of a solution in kerosene or other petroleum fraction. A commercially available produce is YUNIC 500 SB.

The emulsifier should preferably be present in an amount of 6.6 to 11 parts by weight, particularly about 6.7.

The magnesium should be present in the form of an oil-soluble magnesium salt. The magnesium salt is preferably a magnesium naphthenate. The magnesium salt is used in conjunction with anionic surfactant, in particular a long chain alkylene sulphonate. These last two components are conveniently added to the stabilizing agent mixture as a joint solution in an oil medium. Such a solution is commercially available, for example under the Trade Name Apex No. 851 , which is sold in Taiwan by Panta Development Co. Ltd. 51, Sung Chiang Road, Taipei.

The magnesium is preferably present in an amount of from 5.6 to 8.4 parts by weight, preferably about 7 parts by weight and the anionic surfactant is preferably present in an amount of from 1.6 to 2.4 parts by weight, preferably about 2 parts by weight.

The benzoic acid is an optional component, that is to say it may be present or may be present up to the specified content. It is preferably present in an amount of 6 to 9 parts by weight preferably about 6.7 parts by weight. Its role appears to be to aid burning and to further stabilize the oil-water mixture.

Ferrocene (i.e. dicyclopentadienyl iron) is incorporated in the stabilizing agent in order to control burning. It is important that the ferrocene is fully dissolved in oil and evenly distributed throughout the mixture for optimum effect.

The oil-based medium in which the stabilizing agent is formulated is conveniently based on fuel oil or another light oil fraction. Other solvents are preferably incorporated with the oil in order to maintain certain of the components in solution, as explained below. The stabilizing agent according to the invention preferably contains the components in the said ranges of parts by weight in 1 ,000 parts by weight in the solvent medium.Thus for example, a stabilizing agent according to the invention can contain: A combustible emulsifier 6 to 11. 5 g Ferrocene 4 to 9 g Benzoic acid Oto 12g and also, either Magnesium (as an oil-soluble magnesium salt) 4.5 to 9.2 g and An anionic surfactant 1.4 to 3 g or long chain fatty phosphate esters per litre of medium 25-45 g The stabilizing agent according to the invention is conveniently prepared by forming (1) a solution of the magnesium salt and the anionic surfactant, or the phosphate ester, in a paraffin or other moderate to high-boiling petroleum fraction solvent; (2) a solution of ferrocene in oil; (3) a solution of the emulsifier and the benzoic acid (if present) in an organic solvent system; and then combining these three solutions (1), (2) and (3) in any order.The oil used for the ferrocene is preferably fuel oil. The organic solvent for the emulsifier is conveniently an aromatic or araliphatic hydrocarbon solvent, such as benzene, toluene or xylene, especially where the emulsifier is a mixed glyceride.

The benzoic acid is preferably separately dissolved in a more polar solvent, for example a lower alkanol such as methanol, and then this solution added to the solution of the emulsifier to form a mixed solution in an organic solvent system containing the hydrocarbon solvent and the polar solvent.

Once the stabilizing agent has been formed it can be stored indefinitely and is not subject to decomposition or physical separation.

The stabilizing agent is used, according to the present invention, to stabilize an oil-water mixture by adding it simultaneously with water to oil with vigorous mixing. The stabilizing agent and the water may be added separately and simultaneously, which is the preferred method, or alternatively the stabilizing agent may first be added to the water and the "stabilized" water then added to the oil. We have found that it is not so effective to add the stabilizing agent according to the invention to the oil and then add the water.

In a preferred embodiment of the method, the oil is thinned, i.e. its viscosity is reduced, before addition of the stabilizing agent and water. This can be achieved by heating the oil to a moderate temperature, for example about 300 C, by vigorous stirring with a high shearing action, or by dilution with a small amount of a thinner grade of oil.

Once formed, the oil-water mixture comprises a stable emulsion which can be stored at moderate temperatures (i.e. above freezing point and below 400 C) for considerable lengths of time without separation.

In practice, however, the oil-water mixture is best prepared immediately before use, for example by in-line addition of the water and stabilizing agent between the fuel tank and the burner.

The oil-water mixture may contain up to 50% by volume of water although it preferably contains from 10 to 30% by volume and ideally from 18 to 25%. As the water content increases, the amount of stabilizing should also increase and, in general, the ratio of the total of the said components in the stabilizing agents to the water by weight, should be from 1:8,400 to 1:14,000. In a mixture where the said parts by weight are present in a solution in terms of grams per litre, the solution should be added in a weight ratio to water from 1 :250 to 1:420.

The amount of water which can be added to the oil depends largely on the efficiency of the burner system in which the mixed fuel is to be burned. Most water-heating boilers and the like are relatively inefficient and a relatively high proportion of the fuel oil is wasted, either by being emitted unburnt or only partially burnt, thus providing less heat and causing increased pollution. We have found that it is an advantage of the stabilizing agent according to this invention, that the combustion efficiency of the fuel oil is improved, so that a proportion of the fuel can be replaced by water with the same amount of heat being generated. In addition, the more efficient combustion produces less undesirable pollution in the form of soot, carbon monoxide etc.

The ability to replace 20% or more of the fuel oil by water and still obtain the same amount of heat, especially coupled with decreased pollution, illustrates dramatically the importance of the present invention.

The following examples illustrate the invention further.

EXAMPLE 1 A stabilizing agent was prepared by dissolving 6.7 g of a mixed C,2 to C20 fatty acid glyceride in toluene (200 ml); and benzoic acid (6.7 g) in methanol (200 ml); and combining the two solutions.

Ferrocene (7.3 g) was dissolved in about 500 ml of fuel oil and this solution was mixed with the previously formed solution containing the benzoic acid and glycerides. Also added to the mixture was Apex No. (100 ml), found to contain magnesium (7 g) in the form of an oil-soluble magnesium salt including the naphthenate, and an anionic surfactant of the sulphonate type (2 g). The combined mixture was stirred well and added simultaneously with 334 litres of water to fuel oil. A 1:3 by volume water in oil mixture and a 1:4 by volume water in oil mixture were prepared. The mixtures were stable and could be stored at ambient temperature (25 to 350C) for several weeks without separation.

EXAMPLE 2 Comparison of Oil-Water Mix and Fuel Oil A 1:4 water-oil mixture was compared with pure fuel oil in heating 100 litres of water from 250C to 950C.

A standard heating apparatus was used in which preheated oil was injected under pressure into a combustion chamber. The initial internal temperature of the chamber was adjusted to 1 000C, the water temperature to 250C and the pre-heated temperature to 900 C. The oil pressure was 2 kg/cm2. In each run the air intake and oil injection rate were adjusted to provide the optimum setting for smoke-free combustion. For each run the initial fuel volume was measured, the remaining fuel volume was measured and hence the amount of fuel used was obtained.In the test, the results obtained as an average of two runs were as follows: Fuel consumption heavy fuel oil 6.5 kg water-oil mixture 6.4 kg Combustion chamber temperature heavy fuel oil 860"C water-oil 890"C Time required to raise from 250C to 950C heavy fuel oil 24 minutes 30 seconds water-oil mixture 24 minutes 1 5 seconds The results show that the two fuels produce almost exactly the same amount of heat for the same volume consumed. As the water-oil mixture contained 20% water, this results in a saving of 20% of the fuel.

The combustion chamber temperature was found to be 300C higher, but the overall heating time was substantially similar, thus showing that the heat evolved was the same. The oil-water mixture had a viscosity of 1.6 times that of the pure oil and the pre-heater needed to be set 100 higher in order to obtain the same rate of flow.

EXAMPLE 3 Using the same apparatus as in Example 2, but with a 1:3 water-oil mixture, the amount of fuel and the time required to boil a given volume of water from an initial temperature of 1 80C were measured.

During the runs the combustion chamber temperature on average was found to be 700C higher for the water-oil mixture than for the pure oil. The rate of rise in temperature is shown in the following Table.

Minutes Temperature A Temperature B 0 18 18 2 31 30 4 39 36 6 46 44 8 54 50 10 63 58 12 73 67 14 78 75 16 85 80 18 93 85 21 100 93 23 - 100 For the heating runs, the average amount per run of pure oil used was 5 kg and the average amount per run of water-mixture used was 5.23 kg of which 3.975 kg was oil.

From these results it will be seen that at a 1 to 4 ratio,20.5% of fuel is saved. Since the heating time is in fact reduced, the actual fuel saving is, in fact, greater than 20.5%. In addition, the combustion flame was a clear orange as opposed to being orange-red and smokey.

EXAMPLE 4 A stabilizing agent was prepared similarly to that of Example 1, except that the Apex No. 851 was replaced by 100 ml of YUNIC 500 SB, a kerosene-based solution of about 33 g of vegetable oil phosphate esters. A similar product was obtained, which was capable of stabilizing oil water mixtures, although not quite as effectively as the Apex-containing material.

Claims (23)

1. A stabilising agent for an oil-water mixture comprising the following components: A combustible emulsifier 6 to 1 1.5 parts by weight; Ferrocene 4 to 9 parts by weight; Benzoic acid 0 to 12 parts by weight; and also, either Magnesium (as an oil-soluble magnesium salt) 4.5 to 9.2 parts by weight; and An anionic surfactant 1.4 to 3 parts by weight; or long chain fatty phosphate esters in an oil based medium 25 45 parts by weight;

2. A stabilising agent according to claim 1, in which the emulsifier is a mixed glyceride containing mono- di and triglycerides of fatty acids with 1 2 to 20 carbon atoms.

3. A stabilising agent according to claim 1, in which the emulsifier content is 6.6 to 10 parts by weight.

4. A stabilising agent according to claim 1 in which the ferrocene content is 6 to 8 parts by weight.

5. A stabilising agent according to claim 1, in which the magnesium salt is magnesium naphthenate.

6. A stabilising agent according to claim 1, in which the magnesium salt content corresponds to 5.6 to 8.4 parts by weight magnesium.

7. A stabilising agent according to claim 1, in which the anionic surfactant content is from 1.6 to 2.4 parts by weight.

8. A stabilising agent according to claim 1, in which the benzoic acid content is 6 to 9 parts by weight.

9. A stabilising agent according to claim 1, in which the oil-based medium contains fuel oil.

10. A stabilising agent according to claim 1, containing combustible emulsifier 6 to 11.5g ferrocene 4 two 9 9 benzoic acid 0. to 12 g and also, either Magnesium (as an oil-soluble magnesium salt) 4.5 to 9.2 g and An anionic surfactant 1.4 to 3 g or long chain fatty phosphate esters per litre. 25-45 g

11. A stabilising agent according to claim 10 containing mixed fatty acid glycerides 6.6 to 10 g 6.6 to 10 g ferrocene 6 to 8 g 6 to 8 g magnesium (as an oil-soluble salt) 5.6 to 8.4 g anionic surfactant 1.6 to 2.4 g benzoic acid per litre. 6 to 9 g

12. A method of forming a stabilising agent according to claim 1, in which three solutions are prepared: (1) a solution of the magnesium salt and the anionic surfactant, or the phosphate ester, in a paraffin solvent.

(2) a solution of ferrocene in oil (3) a solution of the emulsifier and the benzoic acid (if present) in an organic solvent system; and the three solutions (1), (2) and (3) are then combined.

13. A method according to claim 12, in which the oil is a fuel oil.

14. A method according to claim 12, in which the emulsifier is dissolved in an araliphatic hydrocarbon solvent and the benzoic acid (if present) in a lower alkanol and the two solutions are combined.

15. A method of forming a stabilised oil-water mixture, comprising simultaneously adding water and a stabilising agent according to claim 1 to oil with vigorous mixing.

1 6. A method according to claim 1 5, in which the stabilising agent is first added to the water and the combined mixture added to the oil.

1 7. A method according to claim 15, in which the ratio of agent to water is such that the ratio of the total of the said components to the water, by weight, is from 1:8,400 to 1 :14,000.

18. A method according to claim 15, in which an agent according to claim 9 is added at a weight ratio to water of 1:250 to 1:420.

1 9. A method according to claim 15, in which water is combined with oil to give a product containing up to 50% water by volume.

20. A method according to claim 1 9, in which the product contains 10-30% water by volume.

21. A method according to claim 19, in which the product contains 18 to 25% water by volume.

22. A method according to claim 15, in which the oil is rendered less viscous before addition of the agent and the water.

23. A stabilised oil-water mixture containing a stabilising agent according to claim 1.