JPH0987641A - Improvement of low temperature fluidity of fuel oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the pour point and clogging point of a fuel oil containing wax content in a large amount and prevent thickening of the oil due to admixture of water content by adding a specific amount of a low temperature fluidity improver and a specific fluidity improving auxiliary to the fuel oil in improvement of low-temperature fluidity of the fuel oil. SOLUTION: (A) A low-temperature fluidity improver [e.g. an ethylene-vinyl acetate copolymer having 1000-5000 molecular weight and 5-50wt.% vinyl acetate content] and (B) a nonionic surfactant (e.g. a propylene glycol fatty acid ester or polyoxyethylenealkylphenyl ether) as a fluidity improving auxiliary in an amount of 0.01-50wt.% based on the component A is added to a fuel oil containing middle heavy fraction, especially wax content.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for improving the fluidity of a fuel oil containing a medium heavy fraction (particularly a wax fraction) at low temperatures.

[0002]

2. Description of the Related Art As is well known, fuel oil containing medium and heavy distillates, such as wax, may have a significant decrease in fluidity due to precipitation of wax at low temperatures such as winter, leading to a serious problem. is there. For example, under cold conditions in winter,
A wax component contained in fuel oil (crude oil to heavy oil) may be deposited to cause a big problem such as blocking an oil supply pipe or clogging of a filter provided in a fuel supply system passage of an internal combustion engine. there were. Further, like the heavy oil, when the temperature of the crude oil becomes low, the fluidity is lowered due to the precipitation of the wax component, which makes the transportation impossible and the combustion in the burner is difficult. In addition, while imported crude oil has tended to become heavier in recent years, the demand ratio of distillate fuels such as kerosene, light oil, and heavy oil A tends to increase, which results in heavy oil containing a large amount of high-molecular weight wax components. In order to obtain as much fuel oil as possible from crude oil by distillation fractionation, it is necessary to deep cut crude oil that distills up to high boiling fractions, and as a result, the amount of high molecular weight wax in fuel oil increases. However, since the low temperature fluidity tends to decrease further, a method for improving the fluidity at low temperature has been required. In addition, when wax is deposited in the pipe when the crude oil produced from the oil well is transported by the pipe, the pipe is blocked and the transportability is deteriorated. Further, when the wax deposited on the bottom of the tank during storage in the tank accumulates, the effective volume is reduced. These points were also required to be improved.

Therefore, various methods have been conventionally used for the purpose of maintaining the fluidity of fuel oil under low temperature conditions. For example, there is a method to heat and keep warm with hot water or an electric heater so that the drop in air temperature does not directly lead to a drop in the temperature of fuel oil. Hard to say. So 1
Since the early 960s, studies have been made to improve the low temperature fluidity by adding an additive generally called a low temperature fluidity improver to fuel oil, and some have already been put to practical use. Examples of such a low temperature fluidity improver include ethylene-vinyl acetate copolymer (US Pat. No. 3,048,479).
No.), an ethylene-acrylic acid ester copolymer (US Pat. No. 2,604,453), a copolymer of an ethylenically unsaturated dicarboxylic acid and an α-olefin (JP-A-54-157).
106), an alkyl (meth) acrylate polymer (US Pat. No. 2,091,627), a condensate of chlorinated paraffin and naphthalene (US Pat. No. 18,150,22), and the like. Further, the effect of these low temperature fluidity improvers is not yet sufficient, and in recent years, a method of additionally blending the second component or the third component for the purpose of supplementing the effect has been disclosed. For example, a method in which a second component such as an ethylene-vinyl acetate copolymer is used in combination with an aliphatic amine-modified product of a copolymer of an ethylenically unsaturated dicarboxylic acid and an α-olefin (JP-A-54-81307) ( JP-A-54-86
No. 505), and a method of using n-paraffin wax and a nitrogen-containing compound as second and third components in combination with an ethylene-vinyl acetate copolymer (US Pat. No. 4,210,424).

[0004]

However, the above-mentioned low temperature fluidity improver has a pour point test (JISK-2269).
In the above, all of them show a good pour point lowering effect, but a low temperature filter clogging test (British standard IP-309) for judging clogging of the filter provided in the fuel supply system passage at low temperature In many cases, there is not enough effect. Although the pour point test cannot predict the clogging of the filter of the fuel supply system passage due to the paraffin wax crystal particles precipitated at a temperature considerably higher than the pour point, the low temperature filter clogging test shows the above phenomenon. It is a test method currently widely used for the purpose of predicting. As described above, the conventional low temperature fluidity improvers have not been able to sufficiently improve the low temperature filterability, which is one of the characteristics of the low temperature fluidity of fuel oil having a narrow distillation temperature range. Further, the solubility in fuel oil was often insufficient. Further, few act effectively on heavy gas oil or heavy oil obtained from heavy crude oil containing a large amount of wax such as Minas.

[0005]

The present inventors have arrived at the present invention as a result of earnest research to solve the above-mentioned problems, and when improving the low temperature fluidity of fuel oil,
The low-temperature fluidity improver (A) is used in combination with one or two or more kinds of the low-temperature fluidity improvers (A) that have been conventionally used, and one or more of the low-flowability improvers (B) is added to the low-temperature fluidity improver. It proposes a method for improving low temperature fluidity of fuel oil, which is characterized by adding 0.01 to 50% by weight to (A).

As the low temperature fluidity improver (A) which is the first additive component used in the present invention, a conventionally known one can be used, for example, as described in detail below. There are ethylene-vinyl acetate copolymers, ethylene-acrylic acid esters, nitrogen-containing derivatives of alkenylsuccinic acid and the like, but the substance is not particularly limited.

As the ethylene-vinyl acetate copolymer,
Examples thereof include those having a relatively low molecular weight of 10,000 or less, and those having a vinyl acetate content of 1 to 60% by weight can be used, and preferably a molecular weight of 1000 to 500.
0, and the content of vinyl acetate is 5 to 50% by weight.

Examples of the ethylene-acrylic acid ester copolymer include those having a molecular weight of 30,000 or less, and among these, those having an acrylic acid ester content of 5 to 80% by weight can be used. Further, as the acrylic ester,
It is possible to use from lower alkyl esters such as methyl acrylate and ethyl acrylate to higher alkyl esters such as octyl acrylate and octadecyl acrylate. Preferably, it has a molecular weight of 1,000 to 6,000 and an acrylic acid ester content of 10 to 60% by weight, and as the acrylic acid ester, a lower (C ₁ -C ₄ ) alkyl ester such as methyl acrylate or ethyl acrylate is used. Is.

The nitrogen-containing derivative of alkenyl succinic acid is obtained by reacting an alkenyl succinic acid containing a C ₄ -C ₂₈ alkenyl group or its anhydride with a mono- or dialkylamine or a polyalkylamine, Preferably, it is a reaction product of an alkenyl succinic acid containing a C _{10 to} C ₂₂ alkenyl group or an anhydride thereof and a dialkylamine containing two C _{12 to} C ₂₂ alkyl groups.

The low temperature fluidity improver (A) is usually contained in the fuel oil in an amount of 0.001 to 1.0% by weight, preferably,
It is added so as to contain 0.01 to 0.5% by weight and can be used alone or as a mixture.

The fluidity-improving aid (B) which is the second additional component used in the present invention is a propylene glycol fatty acid ester, glycerin fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester. , Polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyoxyethylene alkylphenyl formaldehyde condensate, polyethylene glycol fatty acid ester, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylphenyl ether , Etc. can be used and are not limited to the above substances, but are generally used as water separating agents Active agents can be used.

The fluidity improving aid (B) is contained in an amount of 0.01 to 50% by weight based on the low temperature fluidity improving agent (A).
Preferably, it is added so as to contain 1 to 40% by weight,
They can be used alone or as a mixture. If the added amount of the fluidity improving aid (B) is less than 0.01% by weight, only the effect due to the combined use can be expected, and if the combined amount exceeds 50% by weight, the effect is not further improved, It is economically disadvantageous.

In the present invention, not only fuel oil but also crude oil and other petroleum products are handled by using the specific amount of the fluidity improving aid (B) together with the low temperature fluidity improving agent (A) as described above. It can be used in all places where precipitation of medium heavy distillates such as wax may occur at low temperature. In the present invention, the method of incorporating the low temperature fluidity improver (A) and the fluidity improver (B) into the fuel oil is not particularly limited. For example, the fluidity-improving agent (A) and the fluidity-improving auxiliary agent (B) may be added to the fuel oil as they are, or the fluidity-improving agent (A) and the fluidity may be added to the fuel oil or a solvent such as an aromatic hydrocarbon solvent. The property improving aid (B) may be diluted and mixed in advance and added to the fuel oil. Furthermore, the low temperature fluidity improver (A) and the fluidity improver (B) may be used in combination with additives such as antioxidants, antifungal agents and antistatic agents which are usually added to fuel oils.

The mechanism of action for improving the low temperature fluidity according to the present invention is not clear, but it is presumed to be as follows since it has an excellent effect particularly in reducing the clogging point. When the fuel oil is cooled, the low-temperature fluidity improver (A) and the low-temperature fluidity improver (A) When the fluidity-improving aid (B) is not added, the paraffin wax crystals generally grow into a plate shape of several hundred μm, and they form a three-dimensional network structure in which a large amount of oil is adsorbed while interlocking with each other. And finally, the whole solidifies and stops flowing.
When the fuel oil added with only the low temperature fluidity improver (A) is cooled, first, the long-chain methylene group of the nucleating agent of the low temperature fluidity improver (A) and n− having a large carbon number in the fuel oil Paraffin and agglomerates are aggregated, and a large number of crystals are formed with the agglomerates as nuclei.
As the crystal is further cooled and the crystallization progresses, the methylene chain length of the wax that precipitates becomes shorter, and the growth inhibitor also comes into the crystal. Since the long-chain methylene group of the low temperature fluidity improver (A) incorporated into the crystal is adjacent to a bulky polar group which hinders crystallization, growth is hindered. Therefore, the wax crystals are refined and show a good pour point depression in the pour point test (JIS K-2269), but the crystal grains are strong, so that the wax crystals have a sufficient pour point in the clogging point test (UK standard IP-309). You can't get a drop in the dead point. On the other hand, when the low temperature fluidity improver (A) and the fluidity improver (B) are used together as in the present invention,
The solubility of the low temperature fluidity improver (A) in the fuel oil becomes high, the crystal particles of the paraffin wax are further miniaturized, and the strength of the crystal particles is weakened to facilitate the shear stress when passing through the filter due to the oil feeding pressure. It is considered that the crystals are broken down into finer particles, the filter passability is improved, and the clogging point is significantly lowered.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION As fuel oil, commercially available No. 1 light oil, No. 2 light oil, and Class 1 heavy oil are used, and the conventional low temperature fluidity improver (A) shown by symbols A to F is used. , And the low-temperature fluidity of each fuel oil was investigated by adding the fluidity-improving aid (B) indicated by symbols a to c. In addition, the same test was carried out for those to which nothing was added. The results are shown in Table 1.

The low temperature fluidity was measured by the method described below. Pour point (PP) ... JIS K2269-1987 Cryogenic filtration plugging point (CFPP) ... IP-309 (UK 1976)
ld FilterPlugging Point o
It was measured by an automatic low temperature filtration clogging point tester (manufactured by Yoshida Scientific Instruments Co., Ltd.) manufactured in conformity with "f Distilate Fuels". The low temperature fluidity improver (A) and the fluidity improver (B) used are as follows. [Low temperature fluidity improver (A)] A: ethylene-vinyl acetate copolymer (molecular weight: 300
0, vinyl acetate content: 30% by weight) a: ethylene-acrylate ester copolymer (molecular weight: 3500, acrylate ester content: 35% by weight) c: condensate of monochlorinated paraffin wax and naphthalene (molecular weight: 5000) d: Polyalkylmethacrylate (alkyl group: C ₁₂ ~
C _20, molecular weight: 17000) o: alkenyl succinic acids and dialkylamines of the amide product (amide product alkenyl: C ₁₅ -C _21, alkyl radical: C ₁₆ -C ₁₈₎ K: the C ₂₈ -C ₅₈ alpha- Copolymer of olefin and maleic anhydride (molecular weight: 12000) [Fluidity improving aid (B)] a: Polypropylene glycol polyethylene glycol ether (molecular weight: about 3500, content of ethylene oxide chain: 40% by weight) b : Polyoxyethylene nonylphenyl formaldehyde condensate (molecular weight: about 5000) c: Decaglyceryl monolaurate

[0017]

[Table 1]

As is clear from Table 1, only the low temperature fluidity improver (A) which does not contain the fluidity improver (B) can achieve the effect of lowering the PP (pour point). The effect of lowering CFPP (cold filtration clogging point) was not sufficient. On the other hand, in the case where the low temperature fluidity improver (A) and the fluidity improver (B) are used in combination, not only the effect of lowering PP (pour point) but also CFPP is obtained.
A sufficient effect (-15 to -18) was also observed for the effect of lowering (low temperature filtration clogging point).

[0019]

As described above, in the method for improving low temperature fluidity of fuel oil of the present invention, a specific amount of the fluidity improving aid (B) is added to the conventional low temperature fluidity improving agent (A). By adding to the fuel oil, the pour point of the fuel oil can be lowered, and the clogging point can be greatly lowered.
It becomes possible to solve various problems relating to low temperature fluidity during storage or transportation of fuel oil having a relatively high boiling point and containing a large amount of wax. Therefore, since it is possible to use even the high boiling point fraction in crude oil, it is possible to increase the production amount of high-quality fuel oil.

Further, by using the fluidity improving aid (B), the water contained in the fuel oil or mixed from the outside is aggregated, and the fuel oil and the water are separated to increase the viscosity due to the water mixture. The effect which can be prevented is also exhibited.

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Claims (1)

[Claims] 1. In improving low temperature fluidity of fuel oil,
In combination with the addition of one or more low-temperature fluidity improvers (A), one or more nonionic surfactants as the fluidity-improvement aids (B) are added to the low-temperature fluidity improvers. (A)
The method for improving low temperature fluidity of fuel oil is characterized by adding 0.01 to 50% by weight based on the above.