Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Reexamination Certificate
2000-06-27
2001-05-08
Ogden, Necholus (Department: 1751)
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
C510S424000, C510S427000, C510S432000, C510S492000, C510S495000, C510S499000, C510S505000, C510S506000
Reexamination Certificate
active
06228830
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to a heavy oil remover formulation. More particularly, the invention is directed to a composition useful for removing heavy oil and oily sludges from process equipment such as storage tanks, transfer piping, and pumping facilities.
BACKGROUND OF THE INVENTION
Compositions for heavy oil degreasing, capable of removing and displacing heavy oils from oil sludges left in process equipment, e.g., oil storage tanks, are known. The conventional heavy oil degreaser compositions contain so-called “alkaline builders.” Moreover, many heavy oil remover compositions include halogens which are undesirable for steel process equipment degreasers, because the halogens may contribute to stress cracking of the metal. Many heavy oil degreasers only work at full strength, and are ineffective when diluted by residual liquids contained within the process equipment being cleaned. Some heavy oil degreasers are ineffective at ambient temperatures and must be heated along with the process equipment in order to remover the heavy oil sludge. Conventional heavy oil removers generally are incapable of absorbing and/or neutralizing the toxic gases and vapors which have accumulated within fouled process equipment.
U.S. Pat. No. 5,085,710 to Goss discloses a composition for removing oil sludges utilizing an alkylphenol adduct and a castor oil etholylate. U.S. Pat. No. 5,389,156 to Mehta et al discloses a heavy oil degreaser including a terpene and a second nonionic co-surfactant from the family of ethylene oxide/propylene oxide polyol adducts. These disclosed formulations suffer from a number of the undesirable characteristics listed above.
It would be desirable to prepare a heavy oil remover composition that is free from alkaline builders and halogens, effective even at significant levels of dilution and at ambient temperatures, capable of absorbing toxic gases and vapors such as hydrogen sulfide and benzene, and nontoxic.
SUMMARY OF THE INVENTION
Accordant with the present invention, there surprisingly has been discovered a heavy oil remover, comprising: from about 1 to about 99 weight percent d-limonene; from about 1 to about 99 weight percent dipropylene glycol mono n-butyl ether; from about 1 to about 99 weight percent salt of an alkyl aromatic sulfonic acid; from about 0.5 to about 99 weight percent carboxylated anionic detergent; from about 0.1 to about 55 weight percent ethoxylated tallow amine; from about 0.1 to about 75 weight percent branched alcohol ethoxylate; from about 0.1 to about 75 weight percent ethoxylated alkyl mercaptan; and up to about 95 weight percent water.
The heavy oil remover according to the present invention is particularly useful for removing residual oil sludges from fouled process equipment such as, for example, oil storage tanks.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The heavy oil composition according to the present invention comprises d-limonene, dipropylene glycol mono n-butyl ether, a salt of an alkyl aromatic sulfonic acid, a carboxylated anionic detergent, an ethoxylated tallow amine, a branched alcohol ethoxylate, an ethoxylated alkyl mercaptan, and water.
The design of a high quality heavy oil remover requires attention to the chemical characteristics related to the performance enhancements required to achieve removal of heavy oils at ambient temperatures. Specifically, the most important chemical characteristics are solvency and detergency (or ability to emulsify). These factors affect the heavy oil remover's ability to clean and degrease metal surfaces, its impact on corrosion of the metal surfaces, its ability to be safely handled, and its environmental acceptability.
The heavy oil remover according to the present invention exhibits the desired characteristics of solvency and detergency. Moreover, halogens are absent from the formulation, thus reducing the potential for stress cracking of the metal process equipment. The inventive formulation is effective at room temperatures, even when substantially diluted with water or residual process fluids. Finally, the composition can absorb toxic vapors such as hydrogen sulfide, yet is itself non-toxic.
D-limonene is a terpene which occurs naturally in all plants. It is a monocylic unsaturated terpene which is generally a by-product of the citrus industry, derived from the distillation of rind oils of oranges, grapefruits, lemons, and the like. A discussion concerning d-limonene and its derivation from numerous sources is set forth in Kesterson, J. W., “Florida Citrus Oil,” Institute of Food and Agriculture Science, University of Florida, December, 1971. D-limonene exhibits low human toxicity and is considered environmentally benign. It functions in the present inventive formulation as a solvent for solubilizing the petroleum sludges, and as an absorbent for benzene contained in the oil sludges and the vapor spaces of the process equipment. Furthermore, d-limonene exhibits excellent solubility for the higher bitumen and asphaltene compounds commonly found in petroleum sludges. D-limonene is commercially available from Florida Chemical Company and from SMC Glidco Organics.
The d-limonene may be present in the inventive formulation at a concentration from about 1 to about 99 weight percent. Preferably, the concentration is from about 22 to about 46 weight percent. Most preferably, the concentration of d-limonene is about 30 weight percent.
Dipropylene glycol mono n-butyl ether according to the present invention acts synergistically with the d-limonene as a second component of the solvent phase. It is a moderately polar solvent, having excellent solvency for petroleum compounds, including waxes, and for other polar compounds present in trace amounts in petroleum sludges. This solvent component is non-toxic, and exhibits a high flash point and low flammability making it safer to use than many other solvents. Finally, it contributes to the overall stability of the inventive formulation and acts as an important coupling agent between the d-limonene and the aqueous phase of the micro emulsion produced using the instant heavy oil remover.
Dipropylene glycol mono n-butyl ether may be present in the inventive formulation at a concentration from about 1 to about 99 weight percent. Preferably, the concentration ranges from about 7 to about 15 weight percent. Most preferably, the concentration of dipropylene glycol mono n-butyl ether is about 10 weight percent.
An amine, alkali metal, or ammonium salt of an alkyl aromatic sulfonic acid is included in the inventive formulation as an anionic emulsifier. The alkylaromatic hydrophobe solubilizes well in petroleum sludges, and the degree of its solubility is modified by the presence of cosurfactants described hereinafter. The alkylaromatic sulfonate bond with the alkyl radical is weaker than a bond between an alkylaromatic sulfonate radical and an alkali metal atom such as sodium. This is important in controlling the degree to which the final product is able to emulsify the petroleum sludge, because a weak emulsion that is easily broken by the presence of minerals in the residual water and fluids in the process equipment being cleaned, is desirable in order to rapidly recover the oil which is ultimately separated. Moreover, the use of an alkylamine salt in a preferred embodiment eliminates the need for an ammonium salt as used in many conventional degreasers. Additionally, this preferred surfactant emulsifier produces little foam, compared to conventional anionic surfactants. Conveniently, this preferred ingredient, due to its weakly bound amine functional group, acts as an aggressive absorber and partial neutralizer for acidic gases such as hydrogen sulfide. Finally, the alkylamine salt according to the preferred embodiment of the present invention is a strong emulsifier for the solvent phase of the heavy oil remover, and contributes to the increased shelf life of the microemulsion formed between the hydrocarbon solvent/dipropylene glycol mono n-butyl ether cosolvent mixture and water.
The required ingredient may be an
Dotolo Research Ltd.
Fraser Donald R.
Ogden Necholus
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