JPH06340885A - Method for improving low-temperature fluidity of fuel oil - Google Patents

Abstract

PURPOSE:To stably obtain a fuel oil with an improved low-temp. fluidity by optimizing the n-paraffin content of a fuel base oil contg. a high proportion of a medium and/or heavy fraction of a crude oil and adding a specific low- temp. fluidity improver to the base oil. CONSTITUTION:The low-temp. fluidity of a fuel base oil contg. 0.1-0.6wt.% 25C or higher n-paraffin and less than 4wt.% wax precipitating at the temp. 10 deg.C lower than the cloud point is improved by measuring the content of the n-paraffin and that of the wax, adjusting if necessary the content of the n- paraffin to 0.1-0.6wt.%, and adding, to the base oil, 30-1500ppm low-temp. fluidity improver comprising an ethylene/vinyl satd.-carboxylate copolymer with an ethylene content of 60-80wt.%, a number-average mol.wt. of 1,000-5,000, and a mol.wt. distribution of 4.0 or lower.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for improving the fluidity of a fuel oil prepared from a heavy fraction of petroleum and a low temperature fluidity improver. As is well known, among the distillates obtained by distilling crude oil, the boiling point called medium heavy fraction is about 150.
The fraction at a temperature of to 450 ° C. is used in large quantities as a fuel source for kerosene, light oil, heavy oil A and the like. Especially, light oil and A
Heavy oil may have serious deterioration in fluidity due to precipitation of a wax component contained in the oil at low temperatures such as in winter, which may cause a serious problem.

[0002] For example, a filter for preventing foreign substances provided in the middle of a line for supplying light oil from a light oil tank to a diesel vehicle in a diesel vehicle for depositing a wax content in the light oil under cold conditions in winter. There is a case where the fine screen incorporated in the unit becomes clogged and the diesel oil cannot be supplied, and the engine stops, and at low temperatures, the entire diesel oil falls into a gelled state and loses its fluidity. . Further, in the case of heavy fuel oil A used for engine driving of fishing boats, warmers for greenhouse heating cultivation, building heating, etc., similar wax precipitation may cause combustion failure, which may seriously affect human life and plants. .

[0003]

2. Description of the Related Art Various measures have hitherto been taken in order to maintain the fluidity of fuel oil at low temperatures. For example, there is a method of heating with hot water or an electric heater in order to keep the temperature of fuel oil so that it does not directly lower the temperature of the fuel oil, but there is a need to improve equipment and burden new energy costs. It is hard to say that it is an advantageous method. There is also a method that has excellent low-temperature fluidity even at relatively low temperatures, for example, by diluting with a kerosene fraction to reduce the amount of wax deposits, but relatively light fuel oil such as a kerosene fraction can be used in demand. However, it is hard to say that it is a preferable method because it has many added values and high added value.

As another method for improving the low temperature fluidity of fuel oil, a method of adding a low temperature fluidity improver is known. The action of the low-temperature fluidity improver affects the precipitation of the wax from the fuel oil, prevents the wax from growing huge and stabilizes it with fine crystals. Various chemical synthetic products have been proposed as the low-temperature fluidity improver, but the effect changes extremely depending on the properties of the target fuel oil, and there was an urgent need to grasp the properties of the fuel oil for stable quality control. Difficulty was caused by many crude oil types and complicated operating conditions of the distillation apparatus.

In order to effectively bring out the effect of addition by the low temperature fluidity improver, several studies have been conducted on the properties of the target fuel oil. For example, JP-A-58-134188 discloses that 100 parts by weight of a middle distillate fuel oil are mixed with an ethylene copolymer and 2 carbon atoms.
The low temperature fluidity is improved by adding 0.2 to 1.5 parts by weight of 6 to 27 n-paraffin. However, in this method, it is necessary to add both ethylene copolymer and n-paraffin to the fuel oil, which not only complicates the equipment and operation but also is a main causative substance of deterioration of low temperature fluidity due to wax precipitation. Since the n-paraffin is positively added, the amount of wax deposited at low temperature increases.
As a result, the fluidity improver often fails to function effectively. When used as a fuel for diesel vehicles, which is a typical application, a strainer is installed in the middle of the fuel supply line, but due to the deposition of a large amount of wax, the wax saturation time in the strainer is shortened, causing early blockage. Therefore, this method is not a preferable method.

Further, Japanese Patent Laid-Open No. 61-58116 discloses a composition in which a pour point depressant is used in light oil in which the amount of paraffin wax precipitated at -20 ° C is adjusted to 5.5 to 12% by weight. However, even if the amount of paraffin wax that precipitates at -20 ° C is specified to be in the range of 5.5 to 12% by weight, the CFPP (cold filtration clogging temperature) does not decrease at all due to the addition of the pour point depressant, In some cases, it cannot be said to be sufficient because the pour point depressant can only lower the temperature.

[0007]

[Problems to be Solved by the Invention] As described above,
In the conventional technology, there is no additive that can improve the low temperature fluidity only to fuel oil having a specific property, and it is necessary to add a considerably large amount of a specific substance other than the additive in order to make the effect of the additive easily manifest. Therefore, it has been extremely difficult to provide a fuel oil having a stable low temperature fluidity. An object of the present invention is to provide a fuel oil having a low-temperature fluidity improved by using a medium- and / or heavy-distillate crude oil as a large proportion of a base oil, and a low-temperature fluidity used for improving the low-temperature fluidity. It is to optimize the amount of n-paraffins contained in the medium and / or heavy distillate of crude oil so that the effect of the property improver can be sufficiently exerted.

[0008]

The present inventors have arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention comprises 1) a large proportion of petroleum medium and / or heavy distillate oil, containing 0.1% by weight or more and less than 0.6% by weight of n-paraffins having 25 or more carbon atoms, and having a cloud point of 10 or more. A method for improving the low temperature fluidity of a fuel base oil in which the amount of wax precipitated at a temperature lower than 40 ° C is less than 4% by weight, the method comprising: (a) the amount of n-paraffins having 25 or more carbon atoms and the cloud point.
A step of measuring the amount of wax precipitated at a temperature of 0 ° C. lower, (b) if necessary, the number of carbon atoms in the fuel base oil is 25
The amount of n-paraffin above 0.1% by weight to 0.6% by weight
And (c) ethylene content of 60 to 80% by weight, number average molecular weight of 1,000 to 5,000, and molecular weight distribution of 4.0 or less at low temperature composed of a copolymer of ethylene and vinyl ester of saturated carboxylic acid. A method comprising the step of adding 30 to 1,500 ppm of a fluidity improver,

2) The method according to the above 1, wherein the amount of the n-paraffin having 25 or more carbon atoms contained in the fuel base oil is 0.2% by weight or more and less than 0.5% by weight, 3) the vinyl ester of saturated carboxylic acid is 4. The method described in 1 above, which is vinyl acetate, and 4) the copolymer of ethylene and vinyl acetate has an ethylene content of 60 to 75% by weight and a number average molecular weight of 1,000 to 4,
000, the molecular weight distribution is 4.0 or less, and the method according to 3 above, which has 6 or less methyl-terminated side chains per 100 methylene groups in the main chain in addition to the methyl group of the acetyl group.

The medium and / or heavy distillate of petroleum used as a large proportion of base oil in the present invention is a distillate obtained by distilling crude oil and has a boiling point of about 150 to 45.
It is a mixture of many components mainly composed of hydrocarbons in the range of 0 ° C. Distillates obtained from general petroleum distillation equipment include light gas oil, heavy gas oil obtained from an atmospheric distillation apparatus, or hydrogenated products of these with a desulfurization apparatus such as a unifiner, or a distillation of an atmospheric distillation apparatus. There are vacuum gas oil and hydrogenated products thereof obtained by distilling bottom oil under reduced pressure with a vacuum distillation apparatus, and these may be appropriately blended depending on the application.

If necessary, a small amount of heavy oil, such as oil treated by a catalytic cracking unit or hydrocracking unit, or the residual oil dewaxed in the production of lubricating oil, is mixed with a small amount of oil generated from a petroleum refining facility. It doesn't matter. Furthermore, a small amount of normal pressure residual oil or reduced pressure residual oil, which is generally used as a method for adjusting heavy oil A, or extract oil produced in the lubricating oil refining step may be mixed.

In the present invention, the amount of n-paraffins having 25 or more carbon atoms contained in the medium-grade and / or heavy-distillate oil of petroleum as the base oil is determined by a usual method using a temperature-increasing gas chromatograph. It is what is analyzed. That is,
A column packed with a packing material consisting of a weakly polar partitioning agent and a porous carrier was used to analyze a trace amount of sample with a hydrogen flame ionization type detector, and the n-paraffin content was determined from the chromatogram of the separated components. Is to seek.

For example, a column packing commercially available from Wako Pure Chemical Industries, Ltd. (Silicone GE SE-30, 2%, 60 /
(80 mesh, Uniport HP carrier) made of stainless steel and packed in a tube with a diameter of 3 mm and a length of 4000 mm was used to inject the sample oil, and the temperature was raised from 70 ° C to 270 ° C at a rate of 5 ° C / min to hydrogen flame. Detect by ionization method. The detected electrical signal is processed by a recorder or data processor as an external output and is obtained by determining the n-paraffin peak.

In the present invention, the amount of n-paraffins having 25 or more carbon atoms contained in the petroleum medium and / or heavy distillate oil as the base oil is in the range of 0.1% by weight to less than 0.6% by weight. Is preferred. When the amount of n-paraffins having 25 or more carbon atoms is less than 0.1% by weight, the effect of improving the low temperature filtration clogging temperature by the low temperature fluidity improver becomes poor, and
If it is more than 0.6% by weight, a very large amount, eg 2,000 ppm
The addition of the above-mentioned low temperature fluidity improver may improve the low temperature filtration clogging temperature in some cases, but the total amount of precipitated wax increases, often resulting in fuel oil that cannot be put to practical use.

The preferable amount of the n-paraffin having 25 or more carbon atoms is 0.2% by weight or more and less than 0.5% by weight, which can further exert the effect of adding the low temperature fluidity improver. Within this range, a relatively low amount of the low temperature fluidity improver can sufficiently lower the low temperature filtration clogging temperature.

Examples of the low temperature fluidity improver used in the present invention are the substances described in "New Edition Petroleum Product Additives" (edited by Toshio Sakurai, published by Koshobo, July 1986), pages 192 to 195. Will be helpful, but more specifically, Japanese Patent Publication Sho 48
-23165, JP-B-55-33480, JP-B-60-17399, JP-A-59-136391 and the like.

Examples of ethylene copolymers include those using one or more vinyl esters of saturated fatty acids such as vinyl acetate, vinyl propionate and vinyl butyrate as comonomers. These are high molecular weight ethylene copolymers. It may be a low molecular weight compound produced as a polymer but decomposed by oxygen, peroxide, heat or the like. In the ethylene copolymer, especially, the ethylene content is 60 to 80% by weight, and the number average molecular weight measured by the vapor pressure equilibrium method is
Those having a range of 1,000 to 5,000 and a molecular weight distribution of 4.0 or less are preferable. Ethylene content is less than 60% by weight or 80% by weight or more, number average molecular weight is less than 1,000 or
When it is 5,000 or more, the effect of improving the clogging temperature of the low temperature filtration becomes slightly poor and a large amount of addition is required, so it is not economically advantageous. The ethylene copolymer may be used alone or as a mixture of two or more kinds. The ethylene copolymer can be mixed and dissolved in fuel oil as it is, but industrially, it can be dissolved in a hydrocarbon solvent,
It is expediently used as a 10 to 90% by weight solution.

Among the above ethylene copolymers, ethylene-vinyl acetate copolymers, which are industrially readily available and have an excellent effect of improving low temperature fluidity, are particularly preferable. More preferred ethylene-vinyl acetate copolymers have an ethylene content of 60 to 75% by weight, a number average molecular weight of 1,000 to 4,000, a molecular weight distribution of 4.0 or less, and a main chain methylene group other than the acetyl methyl group. 100
Since each has 6 or less methyl terminal side chains, it is possible to achieve a further reduction in the low temperature filtration clogging temperature.

The molecular weight distribution is determined by gel permeation chromatography (GPC) method [“Polymer measuring method, structure and physical properties (1)”, edited by Japan Society of Polymer Science, published by Baifukan 1973, No. 7
The method described on pages 6 to 89 can be referred to. ] It is calculated | required from the weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of standard polystyrene conversion.

Further, in the present invention, the degree of branching is expressed by "the number of methyl terminal side chains per 100 main chain methylene groups other than acetoxy group methyl groups", and the nuclear magnetic resonance ( ¹ H-N
MR) method (Journal of the Chemical Society of Japan, 1980, No. 1, 74-)
The method described on page 78 can be referred to. ) Is used for the calculation. That is, in the proton nuclear magnetic resonance spectrum, the peak ratio based on the methyl group and the methylene group is calculated, and is calculated using the vinyl acetate content determined by the saponification method and the number average molecular weight determined by the vapor pressure osmometry. Is. In addition, assuming that both ends of the main chain methylene group are methyl groups and all side chains are ethyl groups, the two terminal methyl groups are subtracted to obtain the value.

The addition amount of the low temperature fluidity improver used in the present invention is preferably in the range of 30 to 1,500 ppm by weight based on the base oil consisting of medium and / or heavy fractions of petroleum,
More preferably, it is in the range of 50 to 1,000 ppm.
When the addition amount is less than 30 ppm, it is hardly expected that the low temperature filtration clogging temperature is lowered, and when the addition amount exceeds 1,500 ppm, it is economically disadvantageous as compared with the obtained effect, which is not preferable. A rust inhibitor, an antioxidant, an antistatic agent, a cetane number improver or an anticorrosive agent may be used in combination with the fuel oil composition according to the present invention.

[0022]

EXAMPLES Hereinafter, the fuel oil composition of the present invention will be specifically described by way of examples, but the present invention is not limited by these descriptions. Various analyzes and measurements of the sample oil used were carried out by the following methods. Specific gravity JIS K2249 (1986), kinematic viscosity JIS K2283 (1986), distillation test JIS K2254 (1986), cloud point JIS K2269 (1986), pour point JIS K2269 (1986),

CFPP (Cold filtration plugging temperature) Cold Filter Pluggi shown in IP-309 (1976 UK)
Automatic low temperature filtration clogging point tester manufactured according to ng Point of Distillate Fuels [A made by Yoshida Scientific Instruments Co., Ltd.
4F2 type].

Amount of Wax Deposition A low temperature fluidity improver "STABINOL (registered trademark) FI-1" commercially available from Sumitomo Chemical Co., Ltd. in 50 g of sample oil.
8 "is dissolved in 200 ppm and cooled in a 100 ml graduated cylinder at a rate of 1 ° C / hr from room temperature to -5 ° C, -10 ° C, or 10 ° C below the cloud point. Oil components other than the wax component precipitated from the cooled sample oil were discharged under reduced pressure through a filter fitting equipped with a 5 μm membrane filter, and 50 ml of cold ethanol / ethyl ether (2/1 volume ratio) was added to the remaining wax component and stirred gently. After that, the oil content is discharged again under reduced pressure. Further, 50 ml of cold methanol was added to the remaining wax content, the entire amount was poured into an 11G4 glass filter and the oil content was discharged under reduced pressure. The wax content remaining on the glass filter was air-dried for one day and night, and then the weight of the wax content was measured to determine the amount of deposited wax. And

Content of n-paraffin The content of n-paraffin in the sample oil was determined by Gas Chromatograph Model GC-9A and Chromatopack C-R2AX data processor manufactured by Shimadzu Corporation. Note that n-triacontane was used as an internal standard substance for quantification. The main operating conditions are shown below. Column: stainless steel, inner diameter 3 mm, length 4 m, column packing material: silicon GE SE manufactured by Wako Pure Chemical Industries, Ltd.
-30, 2%, 60/80 mesh (Uniport HP carrier), injection temperature: 270 ° C, carrier gas: helium, detector: flame ionization method (FID), column heating rate: 5 ° C / min (70 → 270 ° C).

Example 1 Diesel gas oil sample N whose properties are shown in Tables 1 and 2
CFPP was measured by adding 500 ppm of a low temperature fluidity improver containing various types of low temperature fluidity improvers shown in Table 3 as a 50 wt% solution of xylene to o.1 to No. 4. Table 3 shows the results of examining the effectiveness of the effect by the temperature drop (ΔCFPP) from CFPP of the sample oil itself.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

Example 2 Diesel gas oil sample No. 5 shown in Tables 4 and 5
Capacity ratio of No. 9 is 75/25 (Sample No. 6), 50/5
0 (Sample No. 7) and 25/75 (Sample No. 8) were mixed. The properties of the mixed system sample oil are also shown in Tables 4 and 5.

[0031]

[Table 4]

[0032]

[Table 5]

A 60% by weight xylene solution of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 36.5% by weight, a number average molecular weight of 1,690, a molecular weight distribution of 2.4 and a methyl terminal side chain of 3.8 / 100 methylene was added to this sample oil (addition: Agent A) 300
Alternatively, 500 ppm was added and CFPP was measured. Table 6 and Fig. 2 show the results of examining the effectiveness of the effect by the temperature drop (ΔCFPP) from the sample oil itself.

[0034]

[Table 6]

Example 3 Additive A used in Example 2 was added to the fuel oil sample shown in Table 7.
Was added at 500 ppm and CFPP was measured. Of the sample oil itself
The results of examining the effectiveness of the effect by the temperature drop from CFPP (ΔCFPP) are also shown in Table 7 and shown in FIG. Further, the results obtained by using the additive B and the additive C for comparison are also shown in Table 7 and shown in FIGS. 3 and 4, respectively. Additive B was 60% of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 16.5 wt% and a number average molecular weight of 2,200.
The additive C is a 60 wt% xylene solution of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 44.6 wt% and a number average molecular weight of 1,820.

[0036]

[Table 7]

[0037]

[Table 8]

[0038]

As is apparent from the above examples, the content of n-paraffin having 25 or more carbon atoms is less than 0.1% by weight or 0.6% by weight or more, and the cloud point is 10 ° C.
Addition of a low temperature fluidity improver to sample oils in which the amount of wax precipitated at low temperature is 4% by weight or more.
Although it was not possible to obtain a decrease in CFPP, the n-paraffin content was 0.1% by weight or more and less than 0.6% by weight, and the amount of wax precipitated at a temperature 10 ° C below the cloud point was less than 4% by weight. With the sample oil, it was possible to descend, and a remarkable effect was obtained especially for sample oils of 0.2% by weight or more and less than 0.5% by weight. When an ethylene-vinyl acetate copolymer having an ethylene content of 60 to 75% by weight and a number average molecular weight of 1,000 to 4,000 is used as a low temperature fluidity improver, CFPP is significantly lowered, and among them, the molecular weight distribution is 4.0 or less. Further, a more remarkable effect was obtained with 6 or less methyl-terminated side chains / 100 methylene.

[Brief description of drawings]

FIG. 1 is a gas chromatogram of sample oil No. 5 obtained by the method of gas chromatographic n-paraffin analysis shown in the examples, and the portion calculated as n-paraffin is indicated by the diagonal lines.

[Fig. 2] A 60 wt% xylene solution of ethylene-vinyl acetate copolymer having an n-paraffin content of 25 or more carbon atoms, a vinyl acetate content of 36.5 wt% and a number average molecular weight of 1,690 in various sample oils (additive A) Shows the relationship with the drop temperature (ΔCFPP) of the low temperature filtration clogging temperature when 500 ppm is added.

FIG. 3 is an ethylene-vinyl acetate copolymer xylene 6 having an n-paraffin content of 25 or more carbon atoms in each sample oil, a vinyl acetate content of 16.5% by weight, and a number average molecular weight of 2,200.
The relationship with the drop temperature (ΔCFPP) of the low temperature filtration clogging temperature when 500 ppm of a 0 wt% solution (Additive B) was added is shown.

FIG. 4 is an ethylene-vinyl acetate copolymer xylene 6 having an n-paraffin content of 25 or more carbon atoms in each sample oil, a vinyl acetate content of 44.6% by weight, and a number average molecular weight of 1,820.
The relationship with the drop temperature (ΔCFPP) of the low temperature filtration clogging temperature when 500 ppm of a 0 wt% solution (Additive C) is added is shown.

Claims (4)

[Claims] 1. A n-paraffin having a carbon number of 25 or more, which is composed of a large proportion of petroleum medium and / or heavy distillate oil, of 0.
Contains 1% or more and less than 0.6% by weight, and 1 from cloud point
The amount of wax deposited at a temperature lower than 0 ° C is 4% by weight.
A method for improving low-temperature fluidity of a fuel base oil, wherein the amount of wax is (a) the amount of n-paraffins having 25 or more carbon atoms and the amount of wax precipitated at a temperature 10 ° C. lower than the cloud point. (B) If necessary, the amount of n-paraffins having 25 or more carbon atoms in the fuel base oil is 0.1% by weight or more.
Adjusting to less than 0.6% by weight, and (c) ethylene content 60 to 80% by weight, number average molecular weight 1,000 to
5,000, a process comprising the step of adding 30 to 1,500 ppm of a low temperature fluidity improver composed of a copolymer of ethylene having a molecular weight distribution of 4.0 or less and vinyl ester of saturated carboxylic acid. 2. The method according to claim 1, wherein the amount of the n-paraffin having 25 or more carbon atoms contained in the fuel base oil is 0.2% by weight or more and less than 0.5% by weight. 3. The method according to claim 1, wherein the vinyl ester of a saturated carboxylic acid is vinyl acetate. 4. A copolymer of ethylene and vinyl acetate,
Ethylene content 60 to 75% by weight, number average molecular weight 1,0
4. The method according to claim 3, wherein the method has a molecular weight distribution of 00 to 4,000, 4.0 or less, and 6 or less methyl-terminated side chains per 100 methylene main chains in addition to the acetyl methyl group.