JPH0320394A - Turbine oil composition - Google Patents

Abstract

PURPOSE:To obtain a turbine oil compsn. with an extremely long service life and excellent oxidation stability and color stability by using a mineral oil with a specified arom. content as a base oil and incorporating a rustproofing agent and a specified antioxidant. CONSTITUTION:To obtain a turbine oil compsn. from a mineral oil with an arom. content of 8% or less as a base oil and incorporating a rustproofing agent (e.g. an alkenylsuccinic acid) and an antioxidant, 2,6-di-tert.- butyl-4-ethylphenol is used as the antioxidant. Thus, it is possible to obtain a turbine oil exhibiting an extremely long service life, an excellent oxidation stability by which a period for supplying or exchanging the oil can be extended about twice in comparison with the conventional ones and excellent color stability.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an improved turbine oil remedy.

More specifically, it relates to a turbine oil composition that has a significantly long period of use and has excellent oxidation stability and color stability.

(Prior art) Turbine oil is originally a lubricating oil that is used for a long period of 5 to 20 years without being replaced, so it has high oxidation stability, demulsifying property, anti-foaming property, rust prevention property, corrosion resistance, etc. Various types of performance are required. In these cases, it is necessary to use a refined mineral base oil and add various additives. However, with the development of ultra-large steam turbines in recent years, there is an increasing need for turbine oils that can withstand even harsher operating conditions than before, and a particularly high level of oxidation stability is now required. ing. Conventionally, in the turbine oil oxidation stability test specified in JIS K 2514, the acid value after 1000 hours was 1. It is said that it is good if the acid value is less than oqKOH/P, but the current situation is that the acid value is 1.09KOH/P after 2000 and 2500 hours? Turbine oils that are:

Particularly in the case of turbine oil for power generation, in order to cope with these problems, antioxidants are usually added to extremely highly refined base oil.
, 6-ditertiarybutyl-4-methylphenol (
Hereinafter abbreviated as DBPC. ) is used. Furthermore, Japanese Patent Publication No. 59-25834 discloses a product in which tri-p-}lylph t-7ate is added to these.

(Problem to be solved) In the lubricating oil system of power generation turbines, the oil tank is sometimes exposed to reduced pressure in order to remove mixed water, prevent oil from leaking to the outside, and release heated hydrogen for cooling into the oil. In this case, conventional antioxidants have the problem of having to be refueled in a short period of time. In addition, as a guide for bunkering or replacing turbine oil, the cylinder life (results from the rotating cylinder oxidation stability test (JIS K 2514) b, a value that is a guideline for the remaining life of the turbine oil) is 50 to 100. Even if the oxidation stability test is 2,000 to 2,500 hours, bunkering may be required relatively early.

Therefore, a turbine oil with excellent oxidation stability that can further extend the bunkering or oil replacement period is extremely effective.

(Means for Solving the Problem) As a result of intensive studies to solve the above problems, the present invention uses a certain selected base oil and blends a specific antioxidant with it. A turbine oil with excellent oxidation stability and excellent color stability, which has a surprisingly long service life and can extend the period of relubrication or oil replacement by about twice that of conventional oils, has been obtained. find out what you can do,
The present invention has now been completed.

That is, the present invention uses mineral oil with an aromatic content of 8% or less as a base oil and contains a rust inhibitor and an antioxidant, and the nuclear antioxidant is 2,6-ditertiarybutyl-4-ethylphenol. A turbine oil composition characterized in that:

The present invention will be explained in detail below.

The base oil of the turbine oil used in the present invention is highly refined mineral oil. Specifically, it is appropriate to use a mineral oil having an aromatic content of about 8 qb or less, preferably about 2 to 5 qb. If the aromatic content is too large, excellent antioxidant effects cannot be obtained, and if the aromatic content is too small, rust is likely to occur. A method for obtaining mineral oil that satisfies the above conditions can be arbitrarily selected. For example, the base oil can be obtained by subjecting crude oil to atmospheric distillation or vacuum distillation, followed by solvent dewaxing, solvent refining, monoacid clay treatment, solvent refining and hydrogen refining, or hydrocracking, as appropriate. It is necessary to go through a descaling process.

The base oil used in the present invention is obtained through the above-described treatment, but in reality, the aromatic content may be about 8% or less, preferably about 2 to 5%. Generally, lubricating base oils contain various components such as saturated hydrocarbons, aromatic hydrocarbons, and trace components such as sulfur compounds and nitrogen compounds. Normally, it is impossible to analyze the composition of individual compounds in fractions with relatively high molecular weights, such as the base oil of turbine oil.
In practice, composition is determined by performing composition type analysis. Although there are various methods for type analysis, it is preferable to employ liquid chromatography, which allows separation into saturated hydrocarbon components, aromatic hydrocarbon components, and resin components. The base oil used in the present invention must have an aromatic content of about 8% or less, preferably about 2 to 5%, as determined by liquid chromatography analysis. Liquid chromatography analysis is performed as follows.

Activated silica gel packed in a fall tube is moistened in advance with n-hebutane, excipient oil is weighed out, diluted with n-hebutane in the same amount as the sample oil, and injected into the adsorption tube.

Thereafter, specified amounts of n-hebutane, penzey, and methanol are sequentially added and flushed to the bottom of the adsorption tube.

Due to the difference in the adsorption power of the sample oil and each solvent to the silica gel, the sample oil is separated into each hydrocarbon component and eluted. Each hydrocarbon component eluted from the lower end of the adsorption tube is weighed after its solvent has been evaporated.

The proportion (%) of the aromatic hydrocarbon component is determined from the following formula.

Ratio of aromatic hydrocarbon components (%) = Benzene eluate x 100 n-hebutane eluate 10 benzene eluate 10 methanol eluate? Additive used in the invention 2,6 ditertiary butyl
4-Ethylphenol is an antioxidant bC■,H,,
It is a pale yellowish white crystal represented by O (molecular weight: 234, melting point about 43C or more).

Generally, it is obtained by butylating para-ethylphenol and then purifying it. Specific examples of this additive include Swanox 316 (manufactured by Maruzen Petrochemical), Yoshinox 250 (manufactured by Yoshitomi Pharmaceutical), and the like.

The amount added is preferably 0.1 to 1. 0.4, more preferably 0.2 to 0.94. If it is too small, there will be no effect, and if it is too large, the effect commensurate with the amount added will not be obtained.

As the rust inhibitor used in the present invention, ordinary ones can be used. Preferably, alkenylsuccinic acid or a partial ester thereof can be used.

Alkenylsuccinic acid has the following structure. That is, R- CHCOOH 1 CH,COOH where R is an alkenyl group having an average of 12 to 20 carbon atoms, and is usually synthesized by introducing an oligomer of propylene or pudene.

On the other hand, partial esters of alkenyl succinic acids are partially esterified by reacting the upper alkenyl succinic acids with alkylene oxides such as ethylene oxide and propylene oxide or polyhydric alcohols such as ethylene glycol and pentaerythritol. Preferably, the esterification rate of the carboxyl group is 50 or less. The amount added is 0.03 to 1. Ol%, preferably 1, is 0.03 to 0.06. %. If it is too small, there will be no effect, and if it is too large, the antioxidant effect will be hindered. Other rust inhibitors include sulfonates, aliphatic amines, organic phosphorous acids, and sic acid esters.

The turbine oil composition of the present invention contains a rust inhibitor and an antioxidant, and the nuclear antioxidant is 2,6-ditertiarybutyl-4-ethylphenol (hereinafter abbreviated as DBEP).

), but further additives can be added that do not reduce the oxidative stability. For example, a polyacrylate or silicone additive can be added as an antifoaming agent. Further, a phosphorus compound such as tricresyl 7-mole 7-ate can be used as an extreme pressure agent, and a penzotriazole derivative or the like can be used as a metal deactivator. Also, DBPC and DBE
It is also possible to use it in combination with P.

Although the main application of the present invention is turbine oil for power generation, it can also be applied to hydraulic oil, compressor oil, bearing oil, and machine oil.

(Effects of the Invention) The product of the present invention exhibits excellent oxidation stability in a turbine oil oxidation stability test. In particular, the rate of deterioration due to oxidation is about 1/2 that of conventional oil, so it is possible to significantly extend the bunkering or replacement period for power generation turbine oil.

The antioxidant used in the turbine oil composition of the present invention is obtained by changing the methyl group of conventionally used DBPC to an ethyl group, but the oxidation stability is reduced due to the increase of one carbon atom. It is a completely unexpected and serious fact that the improvement is twice as great. In addition, there is little color deterioration and extremely excellent color stability is exhibited.

(Examples) Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited by these.

Examples 1 to 6, Comparative Examples 1 to 4 Additives were added to base oils whose aromatic content had been adjusted to prepare additive turbine oils. The composition is shown in Table 1. In addition, various tests were conducted and evaluated for each of these prepared samples.

<Oxidation stability test {! }> A turbine oil oxidation stability test was conducted in accordance with JIS K 2514. The results obtained are shown in Table 1.

As is clear from the results in Table 1, none of the turbine oils of the present invention were tested for turbine oil oxidation stability, and had low corrosion resistance to steel sheets. It was also found that it has extremely excellent performance.

<Oxidation stability test (2)> Turbine oil oxidation stability test (JIS K 2514
) Samples (50P) were collected at 1,000 hours and 1,500 hours, and the samples were subjected to a rotary pump oxidation stability test (JIS K 2514).
The cylinder life was determined and used as an indicator of remaining life.

The results obtained are shown in Table 2.

As is clear from the results in Table 2, the product of the present invention was tested for turbine oil oxidation stability for 1,000 hours and 1,500 hours.
The cylinder life is high in terms of time, and the remaining life is also long. Therefore, when estimated from the rate of decrease in cylinder life, the Example can be expected to extend the refueling or oil change period approximately twice as much as the Comparative Example.

<Color Stability Test> Changes in color over time were observed at a temperature of 120 C, a sample amount of 50 d, in the presence of both an iron plate and a copper plate (50 x 20 x 1 (m)) as catalysts, or in the absence of a catalyst, over a test period of one week.

The results obtained are shown in Figure 1. As is clear from the figure, the product of the present invention exhibited little color deterioration and exhibited extremely excellent color stability.

[Brief explanation of drawings]

Figure 1 shows the results of the color stability test. The horizontal axis represents time, and the vertical axis represents color (ASTM). The number is 1
, 2...Example 1, 3...Example 5, 4...Comparative example 1, 5...Comparative example 3. The solid line is in the presence of a catalyst, and the broken line is in the absence of a catalyst. Applicant Cosmo Oil Co., Ltd. Tohoku Electric Power Co., Ltd.

Claims (1)

[Claims] 1. Mineral oil with an aromatic content of 8% or less is used as a base oil and contains a rust inhibitor and an antioxidant, and the antioxidant is 2.
A turbine oil composition characterized in that it is 6-ditertiarybutyl-4-ethylphenol.