Fuel and related compositions – Liquid fuels – Containing organic -s
Reexamination Certificate
1998-04-02
2001-03-06
Medley, Margaret (Department: 1714)
Fuel and related compositions
Liquid fuels
Containing organic -s
C044S331000, C044S450000, C508S391000, C508S398000, C508S460000
Reexamination Certificate
active
06197075
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to petroleum fuels and deposit control or sediment reducing additives for such petroleum fuels, as well as to the process for making such additives. The invention more specifically relates to additives to control deposits in residual fuel oils and gas turbine fuels containing high amounts of asphaltenes.
BACKGROUND AND DISCUSSION OF THE PRIOR ART
Petroleum fuels such as residual fuel oils and gas turbine fuels contain vanadium contaminants. These contaminants caused corrosion in the engine or turbine blades. The art recognized that by adding relatively large amounts of magnesium, the magnesium would apparently complex the vanadium and reduce corrosion. It was known to add magnesium, as magnesium sulfate (epsom salt), magnesium acetate, magnesium chloride, magnesium oxide or magnesium carbonate to gas turbine fuels containing vanadium to reduce the corrosion in the turbine blades. One such process is disclosed in U.S. Pat. No. 3,994,699, granted Nov. 30, 1966, to Scott.
Another approach was to add a slurry or paint-like suspension containing substantial amounts of magnesium oxide. The suspension desirably contained 25 to 30% by weight of magnesium, but this paint-like suspension required specialized handling and injection equipment to maintain the magnesium oxide in suspension.
A more recent approach to reducing vanadium corrosion is disclosed in U.S. Pat. No. 5,561,977, granted Oct. 8, 1996, to Harada et al. (“Harada”). Harada disclosed the controlled step-wise addition of metal oxides, e.g., MgO, with initial Mg/V ratios of 2 to 5, in a predetermined cycle of turbine operations.
It was also known in the fuel art to use a magnesium-alkoxide-carbonate complex in combination with an oil soluble sulfonate and a carboxylate and/or phenate dispersing agent as a fuel additive for reducing sediment in vanadium-containing fuels, such as is disclosed in U.S. Pat. No. 4,056,479, granted Nov. 1, 1977, to Redmore et al. (“Redmore”). While the Redmore additives had a magnesium content of about 12.5% to about 14.6%, they generally had undesirable high viscosities.
The fuel art was thus directed to an increased magnesium content additive with practical viscosities.
One attempt to achieve this was to modify the process disclosed in U.S. Pat. No. 4,129,589, granted Dec. 12, 1978, to Eliades et al. (“Eliades”). Eliades disclosed a process for preparing overbased magnesium sulfonate detergents using a promoter system comprised of a lower carboxylic acid, particularly acetic acid, water, and optionally a lower alkanol. The overbased products disclosed in Eliades generally contained only about 9% to 10% by weight of magnesium but were successful detergents for lubrication or engine oils. With controlled or tailored process parameters, the Eliades process produced an overbased product having upwards to no more than about 14% by weight of magnesium with a viscosity below about 200 cSt at 100° C. The Eliades increased magnesium content product had practical viscosities, and achieved acceptance as a fuel oil additive.
Heretofore it was recognized that treating a low (up to about 1% by weight) asphaltene, low aromatic hydrocarbon liquid with an overbased magnesium sulfonate reduced limited asphaltene fouling. This treatment is disclosed in U.S. Pat. No. 4,931,164, granted Jun. 5, 1990 to Dickakian.
More recently it was found that fuel oils, such as residual fuel oils, which contained both high asphaltenes (at least more than 1%, and generally at least 3 to 4% by weight) and highly overbased magnesium sulfonates would, under adverse storage conditions, particularly with water present, produced deposits or sediment containing both magnesium and asphaltenes. This magnesium/asphaltene deposit or sediment plugged the fuel filters. That is, the addition of increased magnesium, while addressing the vanadium corrosion problem, would in combination with high amounts of asphaltenes, cause extensive deposit or sediment.
The fuel art was then faced with the predicament of producing higher magnesium content additives to reduce vanadium contaminant corrosion in the turbine, while where high asphaltenes are present, nonetheless also reduce high magnesium/asphaltene sediment which plugged filters upstream of the turbine.
The fuel art thus desired a high magnesium (i.e., in excess of 14% by weight) additive for a residual fuel oil which reduced, if not eliminated, high magnesium/asphaltene sediment with consequential filter plugging, and yet such high magnesium additive would nonetheless have practical viscosities precluding specialized handling, while also being cost effective.
SUMMARY OF THE INVENTION
This invention is a novel high magnesium content overbased magnesium composition, particularly as a deposit control additive for fuels or fuel oils containing deposit or sediment forming contaminants, particularly asphaltenes. The additive reduces such deposits and the consequential plugging of filters. The invention in another aspect is a fuel oil, such as a residual fuel oil or gas turbine fuel, which contains high amounts of deposit or sediment producing contaminants such as asphaltenes, in combination with the overbased magnesium deposit control additive, which resultant fuel oil has reduced, or is substantially free of, magnesium/asphaltene deposits. The invention in still another aspect is the process for producing such overbased magnesium deposit control additives.
The overbased magnesium additive of the present invention, more specifically, has a magnesium content of at least about 14% by weight, and preferably 14% to 18% or more by weight, and also has a succinic anhydride and lower carboxylic acid overbased co-promoter reaction product. The high magnesium content product is a particularly effective additive for fuel oils, such as residual fuel oils and gas turbine fuels, which contain high amounts of deposit forming contaminants, particularly including asphaltenes and water. This additive when added to fuel oils containing more than 1% or 3 to 4% or more by weight of asphaltenes reduces, if not eliminates, magnesium/asphaltene deposits or sediment. The fuel oil particularly a gas turbine fuel, as previously discussed, contains vanadium corrosion causing contaminants as well. The additive when added in amounts of 2.5:1 to 3:1 of Mg:V, reduces, if not eliminates, both the vanadium caused corrosion and the magnesium/asphaltene caused sediment.
The process for producing the overbased magnesium additive, in broad terms, comprises mixing a sulfonic acid, phenol or carboxylic acid or salt thereof, a magnesium oxide and a co-promoter comprising a lower carboxylic acid and a succinic anhydride, as well as water, a lower alcohol and a solvent, and contacting the mixture with an acidic gas such as carbon dioxide at 50° F. up to the reflux temperature of the mixture to overbase the reaction mixture. The succinic anhydride may be added prior to, during or post carbonation. The volatile components are removed from the overbased mixture to form the highly overbased magnesium additive.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The terms “succinic anhydride and lower carboxylic acid overbased co-promoter reaction product” as used hereinbefore and hereinafter means that on analysis residues of both the lower carboxylic acid and succinic anhydride are found to be present in the overbased magnesium additive.
The invention in one embodiment is the combination of a fuel oil containing high asphaltenes contaminant with a high magnesium content additive comprising a highly overbased magnesium composition comprising a succinic anhydride and lower carboxylic acid copromoter reaction product. The additive contains at least about 14% and upwards to about 18% or more by weight of magnesium. The fuel oil generally contains vanadium contaminant as well. The additive, when present in amounts of magnesium:vanadium of at least about 2.5:1 to about 3:1 or more, reduces, if not eliminates, the vanadium caused corrosion and asphaltene contaminant caused deposit or sediment.
The overbased magnesium add
Eliades Theo I.
Muir Ronald J.
Crompton Corporation
Ma, Esq. Shirley S.
Medley Margaret
Toomer Cephia D.
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