CS231225B1

CS231225B1 - Oils for lubrication of cooling compressor

Info

Publication number: CS231225B1
Application number: CS660882A
Authority: CS
Inventors: Vaclav Stepina; Vladimir Matejovsky; Stanislav Tejkal; Milos Kaplan; Frantisek Cejka; Vladimir Zeman
Original assignee: Vaclav Stepina; Vladimir Matejovsky; Stanislav Tejkal; Milos Kaplan; Frantisek Cejka; Vladimir Zeman
Priority date: 1982-09-14
Filing date: 1982-09-14
Publication date: 1984-10-15

Description

The invention relates to oils for lubricating refrigeration compressors in which it is used as refrigerant ammonia or halogenated hydrocarbons.

At present, synthetic oils (mainly of alkylaromates) are used for lubrication of refrigeration compressors, especially for lubrication of halogenated refrigerant compressors and also for petroleum oils prepared by acid or selective refining of cyclanic oil distillates which have naturally low pour point temperatures and low temperature of paraffin flocculation points, but their thermal and thermo-oxidative stability depends on the method and depth of their refining. They can also be produced by deep dewaxing of alkanic raffinates to pour points below about -50 ° C to provide satisfactory paraffin flocculation point temperatures, whose thermal and thermo-oxidative stability is again dependent on the method and depth of refining. It was an effort to produce cooling compressor oils from alkane raffinates slightly dewaxed to freezing point temperatures down to about -15 ° C and to achieve the required low freezing point temperatures by adding a depressant. Such a process for producing alkane oils for lubricating refrigeration compressors is also described in the description of the invention to U.S. Pat. Certificate No. 214 522.

However, the oils thus produced do not have sufficiently low paraffin flocculation point temperatures, are completely unsuitable for lubricating refrigerant compressors β with halogenated refrigerants and even ammonia compressors with low heat dissipation, and usually not sufficiently heat stable so that they can only be used for lubricating compressors. in which the oil is not too thermally loaded, such as in screw-type ammonia compressors.

Special requirements are imposed on oils for refrigerating compressors, in particular those which use halogenated hydrocarbons, known as freon, ice, frigene, arctone, genetron, isotron, as the refrigerant.

V ' ^{* 1}

231223 the oil is to lubricate the pistons and cylinders, bearings and valves of the refrigeration compressor and seal the seals. However, it is exposed to relatively high temperatures with a cooling effect (halogenated hydrocarbons promote the aging of the oil) and oxygen and moisture. For this reason, the oils must also have good thermal and thermo-oxidative stability up to 250 ° C even when mixed with the refrigerant, and must not form sludge or additions that could prevent the discharge valve from closing, cause piston rings to leak and cause coolant purge, in an oil cooler, promote the deposition of copper and the like, and do not produce thermal decomposition products that promote refrigerant decomposition. This property is evaluated by the so-called Phillips test according to DIN 51 593. The chemical changes of the oil are evaluated according to the intensity of its darkening or according to the amount of visually detectable reaction fumes.

The oil should have a sufficiently low pour point. good fluidity at low temperatures.

In a mixture with freon coolant, flowability improves with increasing coolant content in the mixture. However, it also depends on the hydrocarbon composition of the oil itself.

An important requirement for oil is that it has a sufficiently low paraffin deposition temperature (the so-called paraffin flocculation point) when mixed with a coolant, and that capillaries in the expansion section and control device do not clog the heat transfer.

Often mixtures of oils with halogenated hydrocarbons are deparaffinized at higher temperatures than from the oils themselves, since some halogenated hydrocarbons may act as paraffin precipitants and hence the solubility of paraffins in such mixtures may be less than in the oil alone. However, mixtures of oils with freon coolants (e.g., freon 12) eliminate para-acids at substantially lower temperatures than from the oils themselves, since these halogenated hydrocarbons act as paraffin solvents. The deposition temperature of paraffins from freon / oil mixtures depends on the concentration of oil in the mixture, the higher the temperature. Therefore, the paraffin flocculation point test, for example according to DIN 51 351, is carried out with a content of 10 wt.% Oil in the mixture, which is the most unfavorable limit of the oil content of the circulating refrigerant.

Also important is the mutual solubility of oil and refrigerants at a given temperature, especially in the low temperature range, which depends not only on the type of refrigerant, but also on the hydrocarbon composition of the oil, especially on the aromatic hydrocarbon content. The type of coolant, its content in the oil and its ability to change the viscosity of the oil and its surface tension, is also related to the lubricating (anti-abrasion) ability of the mixture cools with the oil.

Depending on the type of refrigerant, type, design and size of the refrigeration compressor and its operating conditions, the viscosity of the lubricating oil is also chosen. The viscosities of the types of oils used for refrigeration compressors range from 3θ wm ^ / s at 20 ° C to 100 mm / s at 40 ° C.

Of the other properties, the low foaming properties of the oil and its corrosion resistance are also important.

The invention relates to oils suitable for lubricating all types of refrigeration compressors in which ammonia or a halogenated hydrocarbon such as (freon 12) and CIIFgCl (freon 22) is used as the refrigerant. They consist of a high-pressure hydrogenate, dewaxed to a pour point of -20 to -25 ° C and contact-refined, having an aromatic content of _A 2,0 2.0 to 8% by weight, cyclanes C j 25 to 42% by weight. (determined by V -nd analysis), sulfur content pa ... 0.1, 3 thiol. and Minority Index min. 70, and a small amount of a polymethacrylic acid-type depressant, polycrylate, polyvinyl acetate or alkylated naphthalene.

The dewaxed high pressure hydrogenate lid must be selected such that the resulting oil has the desired viscosity when the depressant is added. ·

Example 1

An oil composed in 99.8 wt. high pressure hydrogenated Romaskin oil distillate vacuum oil, paraffinized to a freezing point of ~ 20 ° C and contacted refined, which according to V -nd analysis had 0 ^ 6.1% by weight, 38.2% by weight, sulfur content of 0.06 % wt. and VI 78, and 0.2 wt. polymethacrylate-type depressant (Plexol 102).

The oil obtained had the following quality parameters:

Density, kg / m ^J Refractive Index, α ^ ²⁰

Cinema, viscosity, mm ² / s at 20 ° G Viscosity index Pour point temperature, ° G

The temperature of the flocculation point of peraffins with CF _? C1 _O (DIN 51 351), C Flash point, C Color (ASTM)

Phillip Test (DIN 5! 593)

With cooling CF ₂ C1 ₂ and CHFgCl Asphaltenes

Acid number, mgKOH / g Oxidation stability (ČSN 65 6235)

- acidity number after oxidation, mgKOH / g ·· content of deposits insoluble in n-heptane,

Example 2

874

1.481 8 44.29 81

167

1.0 color change from 1.0 to 1.5, no refrigerant decomposition

0.02

0.15 wt. 0

An oil composed of 99.8 wt. A high pressure hydrogenated vacuum oil distillate of Reaaskin oil, dewaxed to a freezing point of -25 ° C and contacted refined, having a 4.0% by weight analysis of 28% by weight, a sulfur content of 0.08% by weight. and VI 92, and 0.2 wt. polymethacrylate-type depressant (Plexol, O 2).

The oil obtained had the following quality parameters:

Density, kg / ns

Refractive index, n _n • W Ο Λ

Cinema, viscosities, mm / s at 50 ° C at 100 ° C

Viscosity index

Pour point, ° C

Paraffin flocculation temperature (DIN 5! 3515 with CF ₂ C1 ₂ , ° C Flash point, ° C ASTM color

Phillip test (DIN 51 593) with CF2 Clg and GHFgCl

Asphaltenes acid number, mgKOH / g

Oxidation stability (ČSN 65 6235)

- acidity number after oxidation, mgKOH / g

- content of constituents % in n-heptane,% wt

876

1,484 0 4,, 05 ·

9.29.

-36 03

2.5 no color change, no refrigerant decomposition

0.02

0.15

Field test for wear under pressure in a test circuit in accordance with DIN 8978 with the compressor after 9 (speed 1450 min ^-1, the discharge pressure 2 MPa and suction pressure 0.05 MPa), after 500 hours of testing found little or no abrasion of the individual parts (such as connecting rod, shaft, cylinders, front bearing, middle bearings, piston, piston pin).

Example 3

By mixing the oil of Example 1 with the oil of Example 2 in different proportions, oils with different desirable viscosities and all satisfactory quality (utility) parameters can be obtained.

As an example, 2 mixing ratios are given:

Oil

Oil B

Mixing ratio (* weight):

The oil of Example 1. The oil of Example 2

38

62

Quality parameters:

Film, viscosity, mm ² / s at 20 ° C 63.0 - at 50 ° C - 23.0 Viscosity index 85 90 Pour point temperature, ° C -48 -46 Color ASTM 1.5 2.0 Paraffin deposition temperature

Claims

SUBJECT OF THE INVENTION

Oils for lubricating refrigeration compressors using ammonia or halogenated hydrocarbons as refrigerant and good thermo-oxidative stability, complying with Phillips test to DIN 51 593 with halogenated hydrocarbons based on CHFgCl and CFgClg and paraffin flocculation points according to DIN 51 351 with CFgClg below -35 ° C, characterized in that they consist of 99.0 to 99.9 wt. A high pressure hydrogenate prepared by high pressure hydrogenation of an alkane oil distillate vacuum distaffinated to a freezing point of -20 to -25 ° C and contacted refined, containing aromatics C _{A of} 2.0 to 8% by weight, cyclones C _{N of} 25 to 42% by weight. % determined according to V ' -nd analysis, sulfur max. and having a viscosity index of min. 70, and 0.01 to 1.0 56 wt. a polymethacrylate, polyacrylate, polyvinyl acetate or alkylated naphthalene type depreaant.

231226 ₄

SUBJECT OF THE INVENTION

A circuit for transmitting less of two signals, consisting of two operational amplifiers, two diodes and four resistors, characterized in that one input terminal is connected to the non-inverting inputs of the operational amplifiers (1) and (2) and the other input terminal is connected via a resistor. (5) with an inverting input of the operational amplifier (1) to which the diode anode (3) is connected, the cathode of which is connected to the output of the operational amplifier (1), and the diode anode (4), the cathode of which is connected via feedback 6) with an inverting input of the operational amplifier (1) and, on the other hand, through a resistor (7) with an inverting input of the operational amplifier (2), between whose output ,. which is at the same time the output of the whole circuit and the inverting input is connected to the feedback resistor (8), the product of the magnitudes of the feedback resistances (6) and (8) being equal to the product of the resistances (5) and (7).