JPS5891794A - Improvement in fluidity of fuel oil - Google Patents

Abstract

PURPOSE:To prepare a fuel oil excellent in low-temp. fluidity, by adding a specified ethylene (co)polymer mixture to an intermediate or heavy fraction of crude oil. CONSTITUTION:A mixture consisting of 1-99wt% low-molecular polyethylene of number-average MW about 700-5,000 and 99-1wt% ethylene/vinyl ester of saturated carboxylic acid (or alkyl ester of unsaturated carboxylic acid) copolymer such as ethylene/vinyl acetate copolymer is used. Namely, 10-2,000ppm said polymer mixture is added to an intermediate or heavy fraction obtd. by heating and cracking crude oil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for improving the cold flow properties of fuel oils prepared from heavy fractions of petroleum oils.

As is well known, among the fractions obtained by distilling crude oil, the vl, which is called the medium and heavy fraction, has a point of about 150 to 450℃.
The distillate plays an extremely important role as an energy source for the nation as additional oil, light oil, and heavy oil.

Among these, the fluidity of light oils and heavy oils may significantly decrease due to the precipitation of wax contained in the oil at low temperatures such as in winter, which can cause serious problems. For example, in cold winter conditions, the wax contained in diesel oil may precipitate, causing the strainer installed in the circuit (2) that supplies fuel oil to diesel engines to become clogged. There have been many cases where the supply of fuel oil has been cut off, or where diesel engines have become unable to operate due to complete loss of fluidity at low temperatures. In the case of heavy oil, similar problems such as the engine stoppage of fishing boats and combustion problems in greenhouse cultivation boilers have occurred due to similar wax precipitation, which can have a serious impact on human life and property.

For this reason, various methods have been used to improve the fluidity of this type of oil at low temperatures. For example, there is a method of improving the fluidity of light oil or heavy oil by mixing and diluting a refueling fraction that has excellent fluidity at relatively low temperatures.

However, relatively light fractions such as oil retainers are more expensive than light oil or heavy oil, so this cannot be said to be an economical method. Furthermore, in today's situation where crude oil itself is becoming heavier and the need for light fractions is increasing, this method cannot be said to be a preferable method from the viewpoint of effective utilization of petroleum resources.

Another method is method (3) of adding a fluidity improver, and most of these improvers are chemically synthesized products. The role of the fluidity improver is to improve fluidity by preventing the deposited wax from becoming large and stabilizing it as microcrystals. Many types of fluidity improving agents have been proposed, and they are actually added to fuel oil with great effects. Typical fluidity improvers include copolymers of ethylene and alkyl esters of unsaturated carboxylic acids or vinyl esters of saturated carboxylic acids, polyacrylates, alkylnaphthalenes, alkenylsuccinic acids and their derivatives. .

Among them, there are many proposals regarding the use of copolymers of ethylene and saturated carboxylic acid vinyl ester as fluidity improvers, such as Japanese Patent Publication No. 39-20069 and Japanese Patent Publication No. 4B
-23165, Japanese Patent Publication No. 50-7605, and Japanese Patent Publication No. 55-48290.

Among the above copolymers, ethylene-vinyl acetate copolymer in particular not only lowers the pour point of normal fuel oil (4) but also has an excellent effect of lowering the clogging point of cryogenic filters, so in recent years it has been used in increasing amounts. is growing rapidly.

However, they are not always satisfactory because they are effective only for specific fuel oils, and require large amounts of addition despite being relatively expensive.

The present inventors investigated various ethylene-based polymers to improve the low-temperature fluidity of fuel oil, and found that by using a mixture of multiple types of ethylene non-polymers, synergistic low-temperature properties that would not be expected from the use of each individual product were found. It has a synergistic effect on fluidity improvement, especially at the low-temperature filtration clogging point, and can be applied to a wider range of fuel oil types than conventional fluidity improvers, which are only effective for a limited number of fuel oil types. In contrast, the inventors have discovered that the effect of improving low-temperature fluidity can be obtained, leading to the present invention.

That is, the present invention adds 1 ethylene polymer (c) to a fuel oil consisting of medium and/or heavy oil fractions of petroleum.
~99% by weight and a copolymer of ethylene and a vinyl ester of a saturated carboxylic acid or/and (5) an alkyl ester of an ethylenically unsaturated carboxylic acid (B199~1% by weight) based on the fuel oil. Provided is a method for improving the low-temperature fluidity of fuel oil, characterized by adding 10 to 2*000 ppm.

Conventionally, a method for improving cold fluidity by adding an ethylene polymer (Bl) to fuel oil has been known.

However, the effect of improving low-temperature fluidity of these individual products is not sufficient, and the target oil types for which the effect can be exerted are limited.

According to the present invention, ethylene polymer (c)) and (Bl
By mixing these together, a synergistic effect of improving low-temperature fluidity can be obtained that cannot be obtained by using them alone. Furthermore, the effect of improving low-temperature fluidity can be obtained particularly for a wider range of oil types. In particular, the effect of synergistically lowering the clogging point of a low-temperature filter is remarkable.

The present invention will be explained in detail below.

In the present invention, medium and/or heavy oil fractions of petroleum for convenience are those obtained by distilling crude oil at normal pressure or reduced pressure (6) and have a distillation point of about 13
The fraction ranges from 0 to 450°C, and generally includes eaves oil, heavy oil, etc.

The various ethylene thread polymers and (Bl) conveniently used in the present invention can be produced by known methods, such as free radical bulk polymerization, emulsion polymerization or solution polymerization. An advantageous method is free radical bulk polymerization, which can be carried out without using large amounts of solvents.

This method uses a continuous high-pressure polymerization device at a pressure of 500 to 4
,000 instant/♂, free radical group-forming polymerization catalyst under the temperature condition of 100 to 300°C, for example, an azo thread catalyst such as α α′-azobisisobutyronitrile, di-tert-butyl peroxide, peroxide, etc. Propane, butane, propylene, butene,
Propionaldehyde, Methyl Ethylene (7) This is a method in which ethylene alone or ethylene and other comonomers are copolymerized in the presence of a polymerization regulator such as tylketone, tetrahydrofuran, n-butyraldehyde, acetone, or cyclohexanone.

The desired number average molecular weight and copolymer composition of the ethylene thread polymer can be easily obtained by appropriately selecting polymerization conditions such as reaction pressure, temperature, catalyst concentration, chain transfer agent concentration, comonomer sensitivity, etc. I can do it.

Among these, low molecular weight polyethylene having a number average molecular weight of 700 to 5,000 is most suitable as the ethylene polymer (A). Low molecular weight polyethylene can be produced by the above-mentioned method, and polyethylene wax produced as a by-product during the production of cylindrical stitched polyethylene having a number average molecular weight of 5,000 Pl can also be used.

It is also possible to use polyethylene wax obtained by thermal decomposition of high molecular weight polyethylene.

Comonomers copolymerized with ethylene in ethylene thread polymer (Bl) include aliphatic esters such as vinyl acetate, vinyl pro(8) pionate, vinyl butyrate, vinyl octoate, and vinyl stearate.

or methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate,
Alkyl esters of ethylenically unsaturated carboxylic acids or saturated carboxylic acids such as acrylic esters or methacrylic esters such as butyl methacrylate, octyl acrylate, octyl methacrylate, dodecyl acrylate, dodecyl methacrylate, stearyl acrylate, stearyl methacrylate, etc. Examples include vinyl esters.

Among these, vinyl acetate is most preferred.

The ethylene thread polymer concave preferably has a number average molecular weight of 700 to
5,000, more preferably 1.000 to 4,000, and the comonomer unit content is preferably 5 to 50% by weight, more preferably 10 to 40% by weight.

The mixture of ethylene thread polymer 4 and ethylene thread polymer (13) is ethylene thread polymer (A1 1 to 99% by weight (9), preferably 10 to 90% by weight, ethylene polymer 1) 9
It consists of 9-1% by weight, preferably 90-10% by weight.

If the amount of ethylene thread polymer (Bl) is less than 1% by weight or more than 99% by weight, the synergistic effect of mixing can only be obtained within a margin of error, and there is little need for intentional mixing.

The amount of the mixture used in the present invention to be added is suitably in the range of 10 to 2,000 ppm by weight, preferably 30 to 1 '+OOOppm. 110PP
If the amount is less than 2,000 ppm, the effect of addition can only be expected within the error range, and if it is added in an amount exceeding 2,000 ppm, it will be economically disadvantageous compared to the effect obtained by adding it, which is not preferable.

The mixture used in the present invention contains a large proportion of petroleum medium/
There is no particular restriction on the method of adding the ethylene thread polymer (Al and (Bl) to the heavy oil fraction, and the ethylene thread polymer (AI and (Bl) may be added after being mixed in advance, or they may be added separately. It may be added in the form of a concentrated solution dissolved in a suitable solvent.As the solvent, aliphatic hydrocarbons, aromatic hydrocarbons, etc. can be conveniently used.

In addition, at that time, it may be used in combination with rust inhibitors, antioxidants, electrostatic A antistatic agents, or anticorrosion agents that are normally added to petroleum distillate fuel oil, or with other pour point depressants as necessary. It's okay.

The present invention will be explained in more detail below with reference to examples and comparisons, but the present invention is not limited to these examples.

Examples 1 to 6 and Comparative Examples 1 to 8 (1) Preparation of ethylene thread polymer 4 Production of ethylene polymer When polymerizing ethylene using a high-pressure continuous reactor, tert-butyl peroxybenzoate was used as a polymerization initiator. Using propane as a chain transfer agent, the reaction was carried out at a pressure of 1250°C and a temperature of 200°C to produce low molecular weight polyethylene with a number average molecular weight of 1240 and branches of 4.9 methyl groups per 100 carbons. was manufactured.

(Polymer A-1) Polymerization was carried out in the same manner, changing the pressure to 1,000 y/c and the temperature to 240°C, resulting in a number average molecular weight of 1,770 and a carbon
A low molecular weight polyethylene having 6.3 branches per 00 methyl groups was produced. (Polymer A-2) (I3) Production of ethylene copolymer When copolymerizing ethylene and vinyl acetate using a high-pressure continuous reactor, tert-butyl peroxybenzoate is used as a polymerization initiator t) Chain transfer agent Pressure 1400 to 9/cM2 using propane as
, reacted at a temperature of 240°C, number average molecular weight 2.210
A low molecular weight ethylene-vinyl acetate copolymer having a vinyl acetate monomer unit content of 38% by weight was produced. (Polymer B
-1) Polymerization was carried out in the same manner at a pressure of 9ooKy/@ and a temperature of 240°C to produce a low molecular weight ethylene-vinyl acetate copolymer with a number average molecular weight of 3.250 and a vinyl acetate monomer unit content of 28w/J1%. did.

(Polymer B-2) (2) Preparation and evaluation of fuel oils Single items and mixtures of various ethylene copolymers produced by the above method were added to the fuel oils (A) and (A) shown in Table 1. Fuel oils having the compositions shown in Table 4 were prepared and their fluidity was evaluated.

Fluidity was evaluated by measuring pour point and low temperature-overclogging point using the following methods. The measurement results are shown in Table 4.

Pour point: Measured according to JIS K-2269.

Cold Filter Plugging Point: IP-309/1976 UK (Cold Filter Plugging poi
Measurements were made using a 44 micron stainless steel wire mesh in accordance with the National Standards of Distillate Fuel (NT of Distillate Fuel).

(13) Chapter 1 Table

Claims (4)

[Claims] (1) Fuel oil consisting of a large proportion of medium and/or heavy fractions of petroleum contains ethylene polymer (A) 1 to 99% heavy J1%.
and a mixture consisting of 99 to 1% by weight of a copolymer (B) of ethylene and a vinyl ester of a saturated carboxylic acid or/and an alkyl ester of an ethylenically unsaturated carboxylic acid in an amount of 10 to 2000 PPm by weight to the fuel oil. A method for improving fluidity of fuel oil, characterized by: (2) Ethylene polymer (c)) has a number average molecular weight of 7
00 to 5,000 low molecular weight polyethylene. (3) A copolymer of ethylene and a vinyl ester of a saturated carboxylic acid or/and an alkyl ester of an ethylenically unsaturated carboxylic acid has a number average molecular weight of 700 to 5,0
00 low molecular weight ethylene/vinyl acetate copolymer. (4) The method according to claim (3), wherein the low molecular weight ethylene-vinyl acetate copolymer has a vinyl acetate unit comonomer content of 5 to 50% by weight.