RU2184770C1 - Working fluid for hydraulic systems of gas ducts - Google Patents

Abstract

FIELD: gas transportation systems. SUBSTANCE: fluid based of oil fraction with boiling range 165-315 C and designed for hydraulic systems of gas duct stop valves contains 40-60 wt % liquid linear or ramified polydimethylsiloxane with viscosity 20-50 sq.mm/s and 0.5-3.0 wt % ω,ω¹-hexamethyl-methyl(2,6-di-t-butyl-4-methylphenoxy)oligodimethylsiloxane as additive. EFFECT: increased reliability and operation speed of hydraulic drive automatic control system and stabilized operation within wide temperature range (from -70 C to +70 C). 4 tbl

Description

 The invention relates to working fluids for hydraulic systems of valves of gas pipelines.

Strict requirements are imposed on the working fluids of the specified purpose, due to the difficult conditions of their operation, namely: the fluids must remain operational in the temperature range from minus 70 to plus 70 ^o С, stability during the entire storage and operation period, must be inert to the materials of the circuit, have good lubricating properties and not exhibit toxic effects.

 Hydraulic fluids based on marketable fractions of oil and mineral oils are widely used in industry because of their availability and a whole range of positive properties - good lubricity, compatibility with various additives, etc. The disadvantages of this group of products include their tendency to oxidize, a sharp temperature dependence of viscosity, high dissolving ability with respect to gaskets and seals, and high volatility.

Known hydraulic fluid (1 - USSR 721465) based on mineral oil containing 2.6 ditret-butyl-4-methylphenol, a thickening additive and anthranilic acid. According to its technical characteristics, the liquid does not provide stable operation of the taps for more than 6 months at an ambient temperature below minus 55 ^o C. At low temperatures, the viscosity increases sharply, the mechanical load increases when switching the shut-off valves of gas lines.

Closest to the proposed is the working fluid (2) for the hydraulic system of gas pipelines, consisting of a polydimethylsiloxane fluid of linear and branched structure and oil fraction, in the following ratio of components, wt.%:
Polydimethylsiloxane liquid - 40-60
Oil fraction - 60-40 (2 -RF 2079523)
The liquid (2) has good technical characteristics and is currently widely used in the practice of operating gas pipelines. However, the practical operation of the working fluid revealed a number of its shortcomings, which required prolonged research and improvement of the formulation and technology for the production of working fluid. The disadvantages of the liquid, the formulation of which is protected by a patent of the Russian Federation, include:
- the appearance of the crystalline phase during prolonged exposure to low temperatures (at minus 50 ^o C for 20 hours);
- manifestation of the acidity of the product during operation.

 As a result of the influence of these factors during long-term operation (after 3-6 months), the hydraulic drive of the shutoff valves is blocked, the reliability and speed of the automatic control system of the hydraulic drive are reduced. An attempt to improve the characteristics of a hydraulic fluid by introducing additives of the type 2,6-ditret-butyl-4-methylphenol into the composition does not lead to the desired result, since the additive is poorly soluble in it and precipitates.

The technical result of the invention is to increase the reliability and speed of the automatic control system of the hydraulic drive, ensuring high operational characteristics of the working fluid for hydraulic systems in any climatic zone of Russia (from minus 70 to plus 70 ^o C), stable operation of highways without clogging, corrosion and breakage.

гексаметил-метил(2,6-дитретбутил-4-метилфенокси)-олигодиметилсилоксана, взятых в соотношении, мас.%:
Полидиметилсилоксановая жидкость - 40-60
Присадка - 0,5-3,0
Фракция нефти - до 100
Отличительной особенностью изобретения является использование в композиции присадки ω, ω¹- гексаметил-метил(2,6-дитретбутил-4-метилфенокси)олигодиметилсилоксана в сочетании с полиметилсилоксановой жидкостью и фракцией нефти, взятых в определенных соотношениях.This result is achieved in that a composition based on a polydimethylsiloxane liquid of a linear or branched structure having a viscosity value of from 20 to 50 mm ² / s, a fraction of heavy oil with a boiling point of 165 to 315 ^o C, additives is used as the working fluid

hexamethylmethyl (2,6-ditretbutyl-4-methylphenoxy) oligodimethylsiloxane taken in the ratio, wt.%:
Polydimethylsiloxane liquid - 40-60
Additive - 0.5-3.0
Oil fraction - up to 100
A distinctive feature of the invention is the use in the composition of the additive ω, ω ¹ - hexamethylmethyl (2,6-ditretbutyl-4-methylphenoxy) oligodimethylsiloxane in combination with polymethylsiloxane liquid and a fraction of oil, taken in certain ratios.

The use of a substituted oligodimethylsiloxane containing a 2,6-ditretbutyl-4-methylphenoxy group at the silicon atom in combination with the known components of the polydimethylsiloxane liquid and the oil fraction improves the combination of polydimethylsiloxane and the oil fraction in any ratio, increases the stability of the system (the storage life of the mixture without changes - at least 1 year), gives the mixture high lubricating properties (the diameter of the wear spot on a 4-ball machine is from 0.38 to 0.7 mm, optimally no more than 0.5 mm)), and also allows to achieve not Gide effect on the performance characteristics - a liquid of the present composition at low temperatures (below -50 ^o C) is not shown crystalline phase and acidification of the product is not observed during continuous operation (at least 6 months with periodic exposure to low temperatures).

 The authors are not aware of a similar or close technical solution providing reliability and a long service life of shutoff valves of gas pipelines.

 Analysis of the proposed solution and prototype allows us to conclude that the proposed solution meets the criterion of "novelty."

 Characterization of the components of the working fluid.

Physical and chemical indicators:
1. Polydimethylsiloxane liquid (linear or branched structure)
The viscosity value is 20-50 mm ² / sec at 20 ^o С
The density of the liquid is 0.96-0.98 g / cm ³ at 20 ^o C
Pour point - not higher than minus 60 ^o C
Boiling point at a residual pressure of 1-3 mm Hg - above 250 ^o C
The fluid is inert to the structural materials of the hydraulic system of the stop valves.

2. The oil fraction, boiling in the temperature range 165-315 ^o C.

The viscosity value is 4.5 mm ² / s at 20 ^o C
The data are shown in table 2.

 The operational characteristics of the hydraulic fluid were determined according to the accelerated testing program of the GP Orgenergogaz, the data are shown in table 3.

 Physico-chemical properties of the claimed object are shown in table 4.

From the analysis of the examples in tables 1-3, we can conclude: the best characteristics that meet the requirements for working fluids for hydraulic systems of valves of gas lines have working fluids obtained in examples 2-4, 7-9, 13-15. The viscosity at 20 ^o C is 5.7-16.0 mm ² / s. At minus 40 ^o With - 55,0-120 mm ² / sec. The pour point is minus 70-74 ^o С and minus 95-98 ^o С. The temperature of crystallization onset does not crystallize. The acid number is not more than 0.2 mg KOH per 1 g of liquid. The diameter of the wear spot is 0.35-0.50 mm.

 All physico-chemical characteristics of the fluid (examples 2-4, 7-9 and 13-15) remained unchanged in the repeated analysis, conducted after 6 months.

 The indicated properties of the working fluid provided a service life for the hydraulic drive of valves of shutoff valves 180-210 switching cycles from one filling of the fluid and speed for 8-10 seconds (see table 4).

 Thus, from the data given in tables 2, 3, 4, it can be seen that during operation there are no changes in the physicochemical properties of the claimed fluid object, which is a guarantee of the reliability of the hydraulic drive system of the shutoff valves of gas pipelines and allows us to conclude that the proposed solution meets the criterion "industrial applicability".

 An increase or decrease in the amount of additive in the composition (see examples) affects the change in the viscosity characteristics of the working fluid and can provoke the formation of a solid phase at low temperatures.

 An analysis of the results shows that the proposed fluid has a new set of properties and the result is not a result of a summation of the known properties of the components of the proposed composition.

 The described effect reflects a qualitative and quantitative leap in the change in properties that is not predicted based on existing ideas, and therefore is unexpected.

 The authors are not aware of solutions containing features similar to the distinguishing features of the proposed solution with the achievement of the described technical result. All of the above ensures the proposed solution meets the criterion of "inventive step".

Literature
1. USSR author's certificate 721465 of 06/29/1973

 2. RF patent 2079523, B.I. 14, 1997

Claims (1)

The working fluid for the hydraulic system of gas pipelines containing polydimethylsiloxane liquid and a fraction of oil, characterized in that it contains a polydimethylsiloxane liquid of linear or branched structure with a viscosity of 20-50 mm ² / s, a fraction of oil with a boiling point of 165-315 ^o C and an additional additive ω , ω ¹ -hexamethylmethyl (2,6-ditretbutyl-4-methylphenoxy) oligodimethylsiloxane in the following ratio, wt. %:
Polydimethylsiloxane liquid - 40-60
Additive - 0.5-3
Oil fraction - Up to 100

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