CS251740B1 - Oil for air and gas compressors with improved lubricity - Google Patents

Abstract

Oils for air and gas compressors with improved lubricity and longer service life, viscosity classes ISO VG 52, 46, 68, 100 and 150 and complying with classes ISO-L-DAA and ISO-L-DAB for piston compressors, respectively ISO-L-DAG and ISO-L-DAH for screw compressors according to the performance classification ISO 6521, composed of high-pressure hydrogenates ^as base oils and of refining additives, the components of which are a mixture of zinc dialkyldithiophosphates, an oxidation inhibitor of the alkylphenol or alkylbisphenol type, an anti-corrosion additive of the calcium, barium or magnesium alkylarylsulfonate type, an anti-foaming additive of the polysiloxane type and possibly also ash-type detergent-dispersants and a depressant of the polymethacrylate and/or allylnaphthalene type.

Description

The invention relates to an oil with improved lubricating properties for lubricating air and gas compressors.

The basic tasks of lubricating oil are the same for all air and gas compressors: the oil must lubricate the cylinder, piston, piston pin, or seals in reciprocating compressors or screw rotors in lubricated screw compressors, as well as other parts, i.e. bearings, cross pins and guides. The composition and properties of the oil must be adapted to the compressor design and the conditions under which the compressor operates.

One of the basic requirements is that perfect lubrication is achieved with the smallest possible amount of oil. The reasons for this are not only economic (low oil consumption) and ecological (cleanliness of compressed air or gas and low emission of oil aerosol into the environment), but in the case of air piston compressors also safety, i.e. reducing the possibility of explosion and fire in the compressor caused by excessive formation of carbon deposits, the amount of which increases, among other things, with the amount of oil passing through. As a result, it is also required that the oil has good thermal stability, i.e. a low tendency to form carbon deposits and, if possible, a uniform fractional composition, i.e. it does not contain either very light or residual oil fractions.

To achieve low oil consumption with perfect lubrication, it is necessary for the oil to have the best possible lubricating properties. This is achieved not only by choosing the appropriate oil viscosity, but also by adding refining additives that increase the load-bearing capacity of the lubricating film, or

I ^improving the anti-wear properties of the oil.

Moisture also enters the compressor with the air (gas) sucked in. The higher the temperature of the sucked in gas, the greater the

- 2 251 740 is its relative humidity. At higher pressures, moisture can condense in the compressor and at the compressor outlet in intercoolers, aftercoolers, distribution lines and compressed gas reservoirs and cause corrosion. Therefore, the oil is required to have the ability to adsorb on metal surfaces and displace water from them, and to create a protective film on the surfaces against the corrosive effect of water. This is achieved by adding a corrosion inhibitor to the oil.

Modern high-quality oils for lubricating air and gas compressors are produced from high-quality selected petroleum raffinates, preferably cyclanic, which have a low tendency to form carbon. They are also equipped with additives to improve thermo-oxidative stability. According to the tendency to form carbon at high temperatures, these oils are also divided into international classifications, e.g. in the ISO 6521 classification, which also contains limit values for their quality parameters. However, none of these classifications emphasizes the requirement for higher anti-wear (lubricating) ability of compressor oils. However, we have found that by deliberately increasing the lubricating ability of compressor oil, e.g. by combining zinc dialkyldithiophosphates with various alkyls, it is possible to reduce the dosage of oil into the piston compressor* and thus its consumption. In addition, this also reduces the formation of carbon on the discharge, i.e. on the discharge valve and in the discharge pipe, which has a positive effect on extending the correct function of the discharge valve and reducing the risk of explosion and fire in the discharge pipe of air piston compressors. In lubricated screw compressors, the improved lubricating ability of the oil extends the life of the screw rotors.

In terms of thermo-oxidative stability, high-pressure hydrogenates of petroleum oil distillates, especially those that have been stripped of light fractions by redistillation, are better than selective raffinates, especially cyclanic ones. In addition, they have significantly higher viscosity indices. Their thermo-oxidative stability can be significantly increased by using a combination of antioxidants such as peroxide decomposers, preferably zinc dialkyldithiophosphates, and antioxidants such as radical scavengers.

- 3 251 740 with the advantage of alkylphenols and especially the more thermally stable alkylbisphenols. Compressor oils produced on this basis and refined in the above-mentioned way have better thermo-oxidative stability than compressor oils commonly produced today, and a lower tendency to form carbon. They can therefore be used for a longer period of time. An important benefit of screw compressors is that by reducing the formation of thermo-oxidative products, the clogging of oil separators is slowed down and their serviceability is extended.

The essence of the invention is the composition of oils for air and gas compressors with improved lubricity, viscosity classes ISO VG 32, 46, 68, 100 and 150, complying with classes ISO-L-DAA and ISO-L-DAB for piston compressors, respectively ISO-L-DAG and ISO-L-DAH for screw compressors according to the performance classification ISO 6521, characterized in that they consist of high-pressure hydrogenates as base oils, obtained by hydrocracking vacuum distillates of Soviet pipeline crude oil at pressures of 15 to 25 MPa, temperatures of 370 to 420°C, volume velocities of 0.2 to 0.8 m^/m^ on a catalyst composed of 5 to 12% by weight of nickel oxide and 25 to 35% by weight of tungsten oxide or of 5 to 12% by weight of nickel oxide and 15 to 25/& wt. molybdenum oxide on aluminosilicate containing 5 to 15 wt. % silicon dioxide, preferably from those high-pressure hydrogenates which were freed from 10 to 30 wt. % light fractions by redistillation after stabilization, from 0.3 to 1.0 wt. % zinc dialkyldithiophosphate with alkyls up to C _g , from 0.1 to 0.5 wt. % zinc dialkyldithiophosphate with alkyls up to C^, from 0.1 to 0.5 wt. % alkylphenols, preferably 2,6 ditert.butyl-4-methylphenol, or a more thermally stable alkylbisphenol, preferably 2,2 ^, -methylene-bis-(2-methyl-6-tert.butylphenol) or 4,4'-methylene-bis-(2-methyl-6'-tert.butylphenol), with 0.1 to 1.0% by weight of petroleum or synthetic calcium or barium or magnesium alkylarylsulfonate with TBN 5 to 300 mgKOH/g in the form of an oil concentrate containing 30 to 49% by weight.

active substance, and from 0.0005 to 0.01% by weight of polysiloxane, preferably polymethylsiloxane or polyvinylsiloxane, optionally also from 0.5 to 5.0% by weight of detergent-dispersant, which may be 40 to

- 4,251,740

60% oil concentrate of calcium or magnesium alkylphenolate or alkylphenol sulfide with alkyls up to Ο^θ and with TBN 140 to 260 mgKOH/g or calcium or magnesium alkylsalicylate with alkyls Οθ to a and TBN 120 to 180 mgKOH/g or a mixture of both, in which the alkyl salicylate constitutes 10 to 90% or a mixture of the above ash detergents with an ashless dispersant, typically succinimide or Mannich product, in which the ashless dispersant constitutes 10 to 60%, and optionally also with 0.1 to 1.0% by weight of a depressant of the polymethacrylate and/or alkylnaphthalene type.

Example 1.

An oil with improved lubricating properties was prepared for the lubrication of air and gas compressors, which had the following composition:

98.799% by weight of base oil, which was a high-pressure hydrogenate with a viscosity of 10.7 min/s at 100°C and a VI of 92, obtained by hydrocracking heavy vacuum distillate from Soviet pipeline crude oil,

0.45% by weight of zinc dialkyldithiophosphate with i-alkyls and Οθ (Multadit OB/,

0.30% by weight of zinc dialkyldithiophosphate with n-alkyls and Οθ (Oloa 267),

0.30% by weight of 4,4’-methylene-bis-(2-methyl-6-tert.butylphenol),

0.15% by weight of synthetic alkylaryl sulfonate (Nasul BSN) 0.001% by weight of silicone oil (Lukooil II/IIS 200).

The prepared oil had the following quality parameters:

O Λ kinematic viscosity (mm /s) at 40°C 97.50 10.68 91 viscosity index 100°C - freezing point, °C -10 flash point (o.k.), °c 223 aniline point, °C 113 evaporation (Noack), % mass 7.7 ash, % wt. 0.25 CGT, % wt. 0.28

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demulsification characteristics 19-8-53 /10»/ 37-38-5 /30»/ 40-38-2 /60»/ foaming/foam stability: at 24°C 0/0 93°C 70/0 24°C after 93°C 0/0 corrosion to copper /3 h at 100°C/ the oxidation test according to ČSN 65 6235 i CCT after test, wt.% O',73 CCT increase after test, wt.% 0.45

thermal stability test /PNEUROP-test/:

CCT after test, wt% 1.92 CCT increase after test, wt% 1.64

Vickers test:

Stator weight loss, mg 25 Lamella weight loss, mg 3

According to the viscosity at 40°C, it is an oil of viscosity class ISO VG 100. According to the results of the Pneurop test and other tests, the oil meets the condition for inclusion in the performance class ISO-L-DAB. According to the results of the Vickers test, the oil has excellent lubricating (anti-wear) capabilities.

During a 150-hour operational test in a two-stage piston air compressor ČKD 3 DSK 350, the oil demonstrated very good lubricating properties, which made it possible to reduce the dosed amount of oil to below 100 g/h compared to more than 300 g/h with conventional compressor oil.

Such oil can also be used as a hydraulic oil ISO VG 100, performance class ISO-L-HM for filling hydrostatic systems.

Example 2.

An oil with improved lubricating properties was prepared for the lubrication of air and gas compressors, which had the following composition:

- 6,251,740

96. J9% by weight of base oil as in example 1,

0.45% by weight of zinc dialkyldithiophosphate β i-alkyl and Οθ /Multadit OB/,

0.30% by weight of zinc dialkyldithiophosphate and n-alkyls and C&

/Oloa 267/,

0.30 io wt. 2,6-ditert.butyl-4-methylphenol /Antioxidant K 4/, 0.15 9 wt. synthetic barium alkylarylsulfonate /Nasul BSN/,

0.001% by weight silicone oil /Lukooil MS 200/,

1.20% by weight of calcium alkylphenol sulfide with TBN 250 mg KOH/g' /Oloa 219/,

0.80% by weight of bissuccinimide /Oloa 33730/.

The prepared oil had the following quality parameters:

o kinematic viscosity /mmvs/ at 40°G. 98.1

100°C 10.75 viscosity index 92 flash point /o.k./, °C 221 pour point, °C -11 aniline point, °C 110 evaporation rate/Noack/, % wt. 8.1 ash, % wt. 0.6

CCT, & wt. 0.67 demulsification characteristic 15-8-57 /10’/

31-36-13 /30’/ 35-40-5 /60’/ foaming/foam stability:

at 24°C 0/0

93°C, 85/0

24°C after 93°C 0/0 corrosivity per meter /3 h at 100°C/ and oxidation test according to ČSN 65 6235:

CCT after test, also by weight 1.10 CCT increase after test, by weight 0.43 thermal stability test /Pneurop-test/:

CCT after test, also wt. 2.07 increase CCT after test, also wt. 1.40

Vickers test:

stator weight loss, mg 31 lamella weight loss, mg 5

- 7,251,740

According to the viscosity at 40°C, it is an oil of viscosity class ISO VG 100. According to the results of the £neurop test and other tests, the oil meets the condition for inclusion in the performance class ISO-L-DAB. According to the results of the Vickers test, the oil has excellent lubricating /anti-wear/ capabilities.

- 8 SUBJECT OF THE INVENTION

Claims (2)

SUBJECT OF THE INVENTION 251 740 1. Oils for air and gas compressors with improved lubricity, viscosity classes ISO VG 32, 46, 68, 100 and 150, complying with performance classes ISO-L-DAA and 1S0-L-DAB for reciprocating compressors respectively. ISO-L-DAG and ISO-L-DAH for screw compressors according to performance classification ISO 6521 and also usable as hydraulic oils of performance class ISO-L-HM, characterized in that they consist of high-pressure hydrogenates as base oils obtained by hydrocracking vacuum distillates Soviet oil crude oil at pressures of 15 to 25 MPa, temperatures of 370 to 42 ° C, volumetric velocities of 0.2 to 0.8 m ^ / m ^ on a catalyst composed of 5 to 12 wt. % nickel oxide and 25 to 35 wt. % of tungsten oxide or from 5 to 12 wt. % of nickel oxide and 15 to 25 wt. molybdenum trioxide on an alumosilicate containing 5 to 15% by weight of molybdenum oxide; % of silica, preferably from those high pressure hydrogenates which have been de-distilled by 10 to 30 wt. % of light fractions, from 0.3 to 1.0% by weight, of zinc dialkyldithiophosphate with alkyls up to ϋθ, from 0.1 to 0.5% by weight; zinc dialkyldithiophosphate with alkyls to C8, from 0.1 to 0.5% by weight; alkylphenol, preferably 2,6-di-tert-butyl-4-methylphenol or a more thermally stable bisphenol, preferably 2,2'-methylene-bis- (2-methyl-6-tert-butylphenol) or 4,4'-methylene- % of bis- (2-methyl-6-tert-butylphenol), from 0.1 to 1.0 wt. % of petroleum or synthetic calcium or barium or alkyl alkylarylsulfonate with a TBN of 5 to 300 mg KOH / g in the form of an oil concentrate containing 30 to 40 wt. from 0.0005 to 0.01 # wt. polysiloxane, such as polymethylsiloxane or polyvinylsiloxane; from 0.1 to 1.0 wt. depressant type - 9 polymethacrylate and / or alkylnaphthalene. ^{251 740} 2. Oils according to claim 1, characterized in that they contain additional oils 0.5 to 5.0 wt. a detergent dispersant which may be a 40 to 60% oily concentrate of alkylphenol or calcium or magnesium alkylphenol sulphide with alkyls up to and with TBN 140 to 260 mg KOH / g or calcium or magnesium alkylsalicylate with alkyl C8 to C18 qs with TBN 120 to 180 mg KOH / g or a mixture of both in which the alkyl salicylate is 10 to 90% or a mixture of said ash detergents with an ashless dispersant, typically a succinimide or Mannich product, in which the ash-free dispersant proportion is 10 to 60%.