WO2017168312A1

WO2017168312A1 - Compatibilizing and stabilizing composition for fuel oils and process for stabilizing said oils

Info

Publication number: WO2017168312A1
Application number: PCT/IB2017/051754
Authority: WO
Inventors: Marco Buccolini; Milena Mantarro; Viviana BERTO; Danilo ZUFFERLI; Antonio GUARASCIO
Original assignee: Chimec SpA
Current assignee: Chimec SpA
Priority date: 2016-04-01
Filing date: 2017-03-28
Publication date: 2017-10-05
Anticipated expiration: 2018-10-01
Also published as: EP3436553B1; ITUA20162218A1; DK3436553T3; EP3436553A1

Abstract

The present invention relates to a compatibilizing and stabilizing composition for fuel oils (FO) and to a process for stabilizing said oils.

Description

COMPATIBILIZING AND STABILIZING COMPOSITION FOR FUEL OILS AND PROCESS FOR STABILIZING SAID OILS

DESCRIPTION

State of art

Under fuel oils generally mixtures of oils of various nature and/or coming from different origins are designated, generally mixtures of residues from distillation columns (so-called TAR) and hydrocarbon cuts (so-called fluxes) coming from several refinery and petrochemical plants. The Fuel Oils are made by blending different heavy hydrocarbon cuts, which however are not always perfectly compatible therebetween. Some cuts cause a certain instability, that is they include poorely soluble substances in the oilseed matrix, which can precipitate during storage. The evaluation of the instability of an oil is performed by determining the HFT parameter (ASTM D 4870 method) and/or by means of ISO 8217:2012 standard. The specification value allowed for selling Fuel Oil is 0.1 % (0.5% for the Oils intended for civil and industrial thermal uses): above these values the FO is considered too instable and that potentially can give problems during storage or to the burners themselves. The fuel oils are used singularly or, preferentially, in mixture for producing heat for industry (furnaces and boilers) and for the domestic heating or for the energy production (engines). The so-called "heavy" fuel oil (Bunker Oil, Fuel oil) is particularly used for ship propulsion.

Exactly thanks to the fact that they are hydrocarbon-based mixtures such as: paraffins, naphthenes, aromatic and olefins that the fuel oils, for example under the action of the heat, can polymerise and combine with other oil components by forming solid compounds of asphaltene type, which together with possible other solid matter, generate instability to the storage involving negative applicative features. The objective drawbacks which are found due to the fuel oil instability upon use (combustion) are the following:

• Abundant formation of carbon in preheaters, due to the coking of heavy carbonaceous materials

• Abundant formation of soot produced by the incomplete combustion of insoluble heavy compounds, precipitates • Sediments, paraffins and substances similar to rubber found on the lines of the combustion system

As reported previously, the evaluation of an oil instability is performed by determining the HFT parameter (method ASTM D 4870) and/or by means of ISO 8217:2012 standard. Hereinafter (Table A) the specifications established by CTI ("Comitato Termotecnico Italiano") (Italian Thermotechnical Committee) for the liquid fuel oils for civil and industrial thermal uses are shown, based upon a classification of oils which depends upon viscosity (for ex. fluid, heavy, heavy ATZ or BTZ- High or (Low Sulphur Content) and sulphur content which, in Italy, according to "antismog law" and BTZ heavy oil is 1 %. (F.O.=fuel oil)

TABLE A

Table B shows an example of specifications related to a Bunker oil, specifically Fuel Oil 380 for Bunkering (ISO 8217:2012 standard).

TABLE B

Features Value min. -max. ASTM D/!P etf?od

Density °C (kg7m) 991.0 1298

Flash point P.M. (°C) 61 93 Viscosity at 50°C (mm²/s) 380.0 455

Viscosity at 100°C (mm²/s) 35.0 455

Recovered at 350°C (%v/v) <85 86

Total sulphur (%m/m) 4.5 1552

Pour point (°C) 30 613

Water (%v/v) 1.0 97

Sediments per extractions 0.5 95

(%m/m)

Ashes (%m/m) 0.15 473

Compatibility Spot 2 4740

Conradson Residue (%m/m) 18 482

Vanadium (ppm) 300 189. 4530

Aluminium + Silicon (ppm) 80 1548. IP 288

existing HFT (5m/m) 0.1. IP 375

potential HFT (%m/m) 0.1 IP 390B

The tendency of refineries is to maximize the use of poorly precious oils when preparing fuel oils, considering that the fuel oil constitutes the commercial product with lower added value, deriving from petroleum refining.

From what said above the need results evident to develop an additive capable of compatibilizing and stabilizing fuel oils with the purpose of reducing the tendency to precipitate of particles poorly soluble in the oil hydrocarbon matrix and, furthermore to make them compatible with less precious products.

Stabilizing compositions and additives used in the same technological field, described in the following patent publications in the name of the present applicant, belong to the state of art:

WO 2004/033602 wherein the additive to improve the FO stability belonged to the class of alkyl benzen sulfonic acids and related Salts.

WO 2003/099969 wherein the FO instability is improved by adding a mixture of organic phosphite, sterically hindered phenols and formate esters. WO 2008/049887 wherein the FOs coming from a thermal cracking (Visbreaking) are stabilized by adding a radical stopper of nitroxide family.

Now it has been surprisingly found that a composition comprising

- at least a compound belonging to the class of the polyalkylsuccinimides - at least an alkylbenzenesulfonic acid

- at least a compound belonging to the class of imidazolines from fatty acids has stabilizing/compatibilizing effect on the fuel oils and it allows the mixing thereof with poorly precious oils.

Therefore the present invention relates to the composition of claim 1 and the process of claim 12; additional embodiments are described in the other claims.

Brief description of the figures:

Two figures are enclosed to the present description, showing an image of the filters after HFT tests related to a sample not mixed with additive (Figure 1) and one mixed with additive (Figure 2). From these images, it can be noted that the filter of the sample not mixed with additive appears much darker than the one mixed with additive. Description of the invention

The stabilizing/compatibilizing composition for fuel oil of the present invention has the effect of making oils stable in storage and opposing the formation of solids thereof, it is added to oils which, by their nature, are not compatible, but which are mixed therebetween for commercial reasons. Said composition comprises as active principle:

1. at least a compound belonging to the class of the polyalkylsuccinimides (compound A);

2. at least a compound belonging to the class of the alkylbenzensulfonic acids (compound B) and

3. at least a compound belonging to the class of imidazolines from fatty acids (compound C).

The amount of composition according to the invention to be added to the fuel oil can vary with respect to the amount of oil to be treated and it is a function of the stabilization value which the oil final user has set himself/herself. Preferably the amount of composition according to the invention is higher than 10 ppm (weight/weight) with respect to the amount of fuel oil, more preferably it varies in the range 100-1000 ppm, still more preferably 150-700 ppm.

In the composition according to the invention, at least a compound belonging to the class of the polyalkylsuccinimides is selected from the class formed by polyalkylsuccinimides with molecular weight comprised between 500 and 5000 Dalton, having a basicity value comprised between 30 and 80 mg KOH/g and a nitrogen content comprised between 2.0 and 5.0% by weight. Preferred compounds are poly-isobutenyl succinimides, particularly a poly-isobutenilsuccinimide with medium MW between 2000 and 3000 Dalton.

In the composition according to the invention, at least an alkylbenzensulfonic acid is selected from the class formed by sulfonic acids or salts thereof of alkaline and alkaline-earth metals; mono-alkyi or di-alkyl benzen sulfonic acids and salts thereof of alkaline and alkaline-earth metals; mono-alkyi and di-alkyl naphtalene sulfonic acids and salts thereof of alkaline and alkaline-earth metals. Dodecyl or lauryl benzene sulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium, didodecylbenzenesulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium; dinonylnaphthalene sulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium are preferred. Dodecylbenzene sulfonic acid or calcium salt thereof are particularly preferred compounds.

In the composition according to the invention, the at least a compound belonging to the class of imidazolines from fatty acids is selected from the class formed by condensation products among natural, vegetable or animal fatty acids (coming from sebum, talloil, coconut, various oils) and polyamines, in ratios variable from 0.5 : 2 to 2 : 0.5. There are preferred: imidazoline from talloil acids, reacted with diethylenetriamine, in variable ratios from 0.5 : 2 to 2 : 0.5, preferably from 1 : 1 to 1 1.2. Imidazolines synthetized by talloil acids and diethylenetriamine in weight/weight ratio 1 : 1.1 are particularly preferred compounds.

According to the invention the weight ratio between the three components is comprised in the following ratio ranges compound A 1 - 1.5, compound B 0.25 - 1 , compound C 0.06 - 0.24. Preferred ratios between compound A, compound B and compound C are 1 : 0.5 : 0.12 / 1. 5 : 0.5 : 0.12 / 1.5 : 1 : 0.12 / 1.5 : 0.5 : 0.24 or from 1 : 0.5 : 0.12 to 1.5 : 0.25 : 0.12 and 1.5 : 0.5 : 0.06. The ratio 1 : 0.5 : 0.12 is particularly preferred. A particularly preferred composition according to the invention has a ratio by weight 1 : 0.5 : 0.12. between Compound A, Compound B and Compound C (MIX 1), wherein the compound A is a poly-isobutenilsuccinimide with medium MW between 2000 and 3000 Dalton, the compound B is dodecylbenzene sulfonic acid or calcium salt thereof, the compound C is an imidazoline synthetized by talloil acids and diethylenetriamine in weight/weight ratio 1 : 1.1.

Preferably the composition according to the invention is pre-mixed with heavy aromatic naphta (distillation range (187 - 300°C). Under naphtas in the general meaning the products are meant which distil in the temperature range comprised between 30°C and 310°C, these can be obtained directly from raw material or semimanufactured products of the petrochemical industry or from distillates coming from carbon coke distillation.

The solvent (heavy aromatic naphta) is added in amounts so as to constitute by 10 to 90% the formulation of the compounds A, B and C together, being present from 90 to 10% by weight.

By way of example the following ratios can be used: ratio 30 : 70 between solvent and other active principles which is preferred in the best formulation with 60 : 40 % of solvent (40 % of the compounds A, B and C together) or ratio 10 - 90.

The composition according to the present invention can be added to the off- specification fuel oil or to the legal standard fuel oil, which subsequently is mixed with hydrocarbon cuts which bring it off-specification, such as for example CLO (Cyclic Liquid Oil), FOK, Gas oils). In some refineries FO is formulated by using as main component the residue obtained from the unit LC-Finer (RV LCF) and, as additional components, two cuts of the FCC unit: the residue (HCO, sometimes called "slurry oil") and the heavy naphta (HCN: Heavy Catalytic Naphta).

Advantageously the composition of the invention is used for:

bringing back to specification the fuel oils, both those for civil and industrial thermal uses and for bunkering, that is for bringing them back within the established HFT values,

maximizing the absorption, in legal standard fuel oils, of fractions of residues from cracking with low added value and poor compatibility, by keeping the qualitative features requested by the market specifications or by the end user.

increasing the oil stability with the related decrease in the fouling problems in the lines, in the pre-heating trains, in exchangers, in reboilers and other civil and/or industrial plants; economic gain, as the possibility of mixing a product having low added value with others having higher added value is maximized, by controlling the making-dirty capability of the resulting mixture. In addition the invention relates to the method for stabilizing the fuel oils, characterized in that the addition of the additive according to the invention is made on the fuel oil outgoing from the related plant, before being mixed with other hydrocarbon cuts such as for example CLO, FOK, Gas oils, RV LCF(from plant LC- Finer), HCO (sometimes called "slurry oil" of the FCC unit), HCN (Heavy Catalytic Naphta, heavy naphta from FCC).

HFT method is used to determine in the oil sample the total sediments up to 0.5% p/p (ASTM D 4870). In a increasing scale the usually accepted legal standard value is <0.1 %. HFT method provides a hot filtration (100°C, kept by means of a thermostatic jacket heated by vapour), on filters of glass fibre Grade GF/A, with a FO aliquot (about 10 gr) to be analyzed. The filtration is made under vacuum and the sediments remained on the filter are washed with a mixture of solvents (85% n- heptane and 15 % toluene). The deposit is weighed and compared to the weight of filtered tar: the result is expressed as percentage of sediments remained on the filter.

The composition of the present invention increases the blending stability of the several cuts therewith the FO is formulated and it allows an off-specification FO (HFT greater than 0.1/0.5 %) to return easily to the sale specification.

Some illustrating, but not limiting, examples of the invention are shown hereinafter. The composition according to the invention (Mix 1) was used compared to other formulations: Mix 2, Mix 3, Mix 4 and Mix 5.

Mix 1 : Compound A : Compound B : Compound C, ratio by weight 1 : 0.5 : 0.12 wherein compound A is a poly-isobutenilsuccinimide with medium MW between 2000 and 3000 Dalton, compound B is dodecylbenzene sulfonic acid or calcium salt thereof, compound C is a imidazoline synthetized by talloil acids and diethylenetriamine in weight/weight ratio 1 : 1.1 in heavy aromatic naphta

Mix 2 : Compound A : Compound B ratio by weight 1 : 0.55 wherein compound A is a poly-isobutenilsuccinimide with medium MW between 2000 and 3000 Dalton, the compound B is dodecylbenzene sulfonic acid or calcium salt thereof, in heavy aromatic naphta

Mix 3 : Compound A : Compound B ratio by weight 1 : 0.43 wherein compound A is a poly-isobutenilsuccinimide with medium MW between 2000 and 3000 Dalton, the compound B is dodecylbenzene sulfonic acid or calcium salt thereof, in ethyl-hexyl nitrate solvent

Mix 4 : propylene diamine from coconut in isobutanol

Mix 5 : mixture of polyvinylpyrrolidones in N-methyl pyrrolidone Example 1

The effectiveness test of the various mixtures was performed by mixing two FOs not compatible therebetween, which then provide a HFT-high end mixture. FO mixture nr.1

Blank HFT 0.32 %

Mix 1 -150 ppm HFT 0.08 %

Mix 1 - 300 ppm HFT 0.07 %

Mix 2 - 150 ppm HFT 0.28 %

Mix 2 -300 ppm HFT 0.11 %

Mix 5-150 ppm HFT 0.11 %

Mix 5 - 300 ppm HFT 0.09 %

Mix 4 - 150 ppm HFT 0.10%

Mix 4 -300 ppm HFT 0.10%

FO mixture nr.2

Blank HFT 0.52 %

Mix 1 - 300 ppm HFT 0.09 %

Mix 5 - 300 ppm HFT 0.12%

Mix 4 -300 ppm HFT 0.12%

FO mixture nr.3

Blank HFT 0.15%

Mix 1 - 300 ppm HFT 0.07 %

Mix 2 -300 ppm HFT 0.12%

Mix 4 -300 ppm HFT 0.08 %

Mix 5 - 300 ppm HFT 0.08 %

FO mixture nr.4 (Residue Visbreaking 69% + LCGO 17 % + automotive Gas oil 5 % + Gas oil from cracking 9 %)

Blank HFT 0.06 % Potential HFT 0.10 %

Mix 1 - 500 ppm HFT 0.06 % Potential HFT 0.09 %

Mix 1 - 800 ppm HFT 0.05 % Potential HFT 0.04 %

Mix3- 800 ppm HFT 0.06 % Potential HFT 0.09 %

Mix4 - 800 ppm HFT 0.05 % Potential HFT 0.05 %

FO mixture nr.5 (Residue Visbreaking + LCGO 86 % + automotive Gas oil 5 % + Gas oil from cracking 9 %)

Blank HFT 0.12% Potential HFT 0.63% Mix 1 - 800 ppm HFT 0.07 % Potential HFT 0.17 %

Mix 4 - 800 ppm HFT 0.07 % Potential HFT 0.17 %

Mix 3 - 800 ppm HFT 0.08 % Potential HFT 0.21 %

5 Tests performed with mixtures of compounds A, B and C at different ratios with respect to that used in Mix 1 provided slightly different results, but which from the quality point of view are not significantly different from the above-illustrated results.

Example 2: Bunker Fuel Oil "RMG 380"

0 In this test there has been verified the possibility of producing Bunker Fuel Oil pursuant to ISO 8217:2012 standard, by using as main component the residue obtained from the unit LC-Finer (RV LCF) and, as additional components, two cuts of the unit FCC: the residue (HCO, sometimes called "slurry oil") and the heavy naphta (HCN: Heavy Catalytic Naphta). The base production scheme provides the 5 preparation of a first heavy fraction, obtained by mixing in the percentage ratio 77/23 the two residues RV LCF and HCO directly in line. Subsequently the above- mentioned heavy fraction is diluted with HCN, generally added between 12 and 14%.

The added HCN amount has to be so as to reach the viscosity and density limits of 0 the Bunker Fuel Oil type which one wishes to produce, pursuant to ISO 8217-2012 standard, respectively equalling to:

- Viscosity @50°C: max. 380 cSt

- Density @15°C: max. 0.991 g/cm3

The requested HFT limit is max. 0.10 % (m/m), not only on the sample as such, 5 but even as potential HFT value (ageing at 100°C for 24 hours) of the Bunker

Fuel Oil. Table 1 shows the characterization analysis of all used cuts and the mixtures thereof.

Table 1

From the detected values, shown in Table 1 , it is noted that the values of current and potential HFT of Residue LC-Finer are extremely high, whereas the HFT of mixture RV LCF/HCO (77/23) are lower than the mentioned residue due to high 5 aromatic quality of HCO (90.5 %).

By adding the HCN cut, the potential HFT value worsens, most probably due to the destabilization caused by this slightly aromatic and much more paraffinic cut (saturated 91.7 %).

The stabilizing/compatibilizing mixture (HFT reducer), later called Mix 1 , used in this 0 test is constituted by:

1. a polialkylsuccinimmide (40 - 50 %)

2. an alkylbenzensulfonic acid ((20 - 30 %)

3. an imidazoline from fatty acids (5 - 10 %)

4. heavy aromatic naphta, up to 100 %

5 Mix 1 was additioned at the bottom of the column LC-Finer, before mixing with the flux HCO. The storage temperature of Bunker Fuel Oil in reservoir 63 was 70°C. The Current and Potential HFT values were evaluated and the finished FO (RV LCF + HCO) was characterized. The following table show the values of density @15°C, Viscosity @50°C and Total Sulphur: Table2

Table 3

The following table shows the HFT values of the samples shown in Table 2.

The results of Current and Potential HFT of the samples mixed with additives are all results below the value of 0.1 % (m/m), the additive action was found with an average 50% reduction in the starting HFT value with effectiveness maximum reaching about 70% reduction. The HFT value of the samples mixed with additives was within the HFT specification even after 3 days at 100°C.

Example 3: Determination of Current and Potential HFT on finished FO (mixed with additives) + HCN (added in laboratory):

Table 4

The following table shows the characterization of the blends reconstructed in laboratory by adding 17% of HCN:

As it can be seen the samples of the mixture RV LCF + HCO (mixed with additives) reaches the specification of density/viscosity by adding 17% of HCN. Table 5

The following table shows the Current and Potential HFTs performed on the mixture reconstructed in laboratory by adding 17% of HCN:

Potential Potential

Potential Potential HFT HFT

Finished OC (RV LCF + HCO) +

HFT HFT 48 hours at 72 hours at HCN al 17%

% w/w % w/w 100°C 100°C

% w/w % w/w

Sample 1 (RV LCF + HCO) + HCN 0 06 0 06 n.a n.a Sample 2 (RV LCF + HCO) + HCN 0.06 0.07 0.08 n.a

Samp le 3 (RV LCF H HCO) + HCN 4 0.06 0 .06%

Samp le 4 (RV LCF + HCO) + HCN 0.05 0.03 [ 0.05% [ 0 .06%

Samp le 5 (RV LCF HCO) 11 HCN 1 0.03 0.04 0.05% 0 .06% Even in this case, after complete finalization of the blending of Bunker Fuel Oil, all analyzed samples are within the specification of Current and Potential HFT.

Moreover, the HFT value of the samples mixed with additives are widely within the HFT specification even after an ageing of 3 days at 100°C.

Example 4: Determination of Current and Potential HFT of the final Bunker Fuel Oil finale (with addition of HCN).

For completing the industrial test, the FO is constituted as follows:

- 63% RV LCF

- 16% HCO

- 21 % HCN

The additive final dosage, recalculated on the whole final blend, including the HCN amount, was about 475 ppm. In the following tables 6 and 7 the results related to the final FO characterization (including HCN) are shown:

Table 6

Table 7

Claims

1. A composition comprising

- at least a compound A belonging to the class of the polyalkylsuccinimides; - at least a compound B belonging to the class of the alkylbenzensulfonic acids and

- at least a compound belonging to the class of imidazolines from fatty acids

2. The composition according to claim 1 , wherein said at least a compound A is selected from the class formed by polyalkylsuccinimides with molecular weight comprised between 500 and 5000 Dalton, having a basicity value comprised between 30 and 80 mg KOH/g and a nitrogen content comprised between 2.0 and 5.0% by weight, preferably poly-isobutenyl succinimides.

3. The composition according to at least one of the preceding claims, wherein said at least a compound B is selected from the class formed by sulfonic acids or salts thereof of alkaline and alkaline-earth metals; mono-alkyl or di- alkyl benzen sulfonic acids and salts thereof of alkaline and alkaline-earth metals; mono-alkyl and di-alkyl naphtalene sulfonic acids and salts thereof of alkaline and alkaline-earth metals.

4. The composition according to claim 3 wherein said compound B is selected from the class formed by dodecyl or lauryl benzene sulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium, didodecylbenzenesulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium; dinonylnaphthalene sulfonic acid and salts thereof of Sodium, Potassium, Calcium and Magnesium.

5. The composition according to claim 4, wherein said compound B is dodecylbenzene sulfonic acid or calcium salt thereof.

6. The composition according to at least one of the preceding claims, wherein said at least a compound C is selected from the class formed by condensation products among natural, vegetable or animal fatty acids (coming from sebum, talloil, coconut, various oils) and polyamines, in ratios variable from 0.5 : 2 to 2 : 0.5.

7. The composition according to claim 6, wherein said at least a compound C is selected from the class formed by imidazoline synthetized by talloil acids and diethylenetriamine in weight/weight ratio 1 : 1.1

8. The composition according to at least one of the preceding claims, wherein the weight ratio between said at least a compound A, B and C is comprised in the following ratio ranges compound A 1 - 1 .5, compound B 0.25 - 1 , compound C 0.06 - 0.24.

9. The composition according to claim 8, wherein the weight ratio between said at least a compound A, B and C is 1 /0.5 /0.12.

10. The composition according to at least one of the preceding claims further comprising heavy aromatic naphta in amounts comprised between 10 and 90% by weight referred to the weight of the composition as claimed in at least one of claims 1 to 8.

1 1. Use of the composition as claimed in at least one of claims 1 to 10 as stabilizer/compatibilizer of fuel oils.

12. A process for stabilizing fuel oils wherein the composition as claimed in at least one of claims 1 to 10 is added before mixing with the cuts to be normalized in a greater amount than 10 ppm (weight/weight), preferably in the range 100-1000 ppm, still more preferably 150-700ppm.

13. Stabilized fuel oils which can be obtained according to the process of claim 12.