Method of estimation of evaporation of mineral lubricating oils

 

(57) Abstract:

The invention relates to the field of study of lubricating oils and may find application in industries engaged in the warehousing and storage of oil products, particularly mineral lubricating oils in assessing their evaporation. The purpose of the invention is to increase the reliability of the estimation of evaporation of mineral lubricating oils by increasing the amount of the evaporated oil when heated in laboratory conditions without chemical change in the oil. This is achieved by the fact that in the tested oil is added as a scavenger N,N-dimethylformamide, at a ratio of 1:(1,9-2,1); evaporation is conducted at a temperature of 1541oC (below the temperature of the beginning of decomposition of the heat-sensitive additives) under vacuum for 2 h table 3.

The invention relates to the field of study of lubricating oils and may find application in industries engaged in the warehousing and storage of oil products, particularly mineral lubricating oils in assessing their evaporation.

In air cushion tanks filled with oil, there are always pairs of the latter. If certain organizational and technical is CLASS="ptx2">

The structure of the loss of oil from evaporation in reservoirs refinery is characterized, for example, the following data: loss from ventilation 60-65% of the "big breaths" and "reverse out" 32-34% of the "small breaths," 3-6% [1 - Transport and storage of petroleum products and hydrocarbon, CNITA Neftekhim, M. 1978, N 5]

In the vapor phase content of light fractions of oil higher than in the volume. Loss of light fractions of the oil during storage leads to increase in viscosity and changes in other indicators of the quality of the oil. For reliability estimation of evaporation it is necessary to develop a way that excludes, for example, the oxidation taking place in the oil during storage, and also allows you to get the most number of evaporated oil and eliminates thermal decomposition framework and functional additives.

To estimate the evaporation of lubricating oils was developed by a group of methods. These methods are based on the determination of the loss of oil after heating them to a certain temperature.

Methods vary according to the heating temperature, the pressure (sparse, atmospheric, high); some methods include blowing air or inert gas.

So, the simplest of means of the different engines. Method for the determination of evaporation in cups] providing heating to 175oC; evaporation occurs in static conditions. To him the close method for the determination of evaporation and thin film oxidation of essential oils for aircraft GTE (Rogers A. R. J. Pharm. 1963, v. 2. N 15, p. 101-105). To this group "static" methods include a method of Golde, English method CEC-L-40-T-87, American method ASTM d 2887 and method for determining the evaporation time of the oil (GOST 7934.1-74. Oils and greases time. Method for the determination of evaporation). These methods are only suitable for the evaluation of light (distillate) oil and do not consider group composition mixed and residual oils.

In contrast to the above methods in the standard American method ASTM d 972 in addition to heating produce blowdown evaporation chamber with dry air. In addition to the long duration of trials (22 h 5 min) one of the drawbacks of this method is the relatively high temperature gradient experiment (service 99 stops 150oC), which does not allow to differentiate between evaporation modern and promising oil.

In a number of methods to promote the evaporation process applied vacuum.

In various methods, the residual pressure changes otted ASTM d 2715 and method VNII NP using installation PFP BB).

To determine the evaporation of oils (and any other products) are used methods of thermography and the use of various laboratory equipment, including derivatograph.

The closest technical solution of the present invention is used as a prototype method of determining loss of oil from evaporation in dynamic conditions (GOST 10306-75. The lubricating oil. Method for the determination of evaporation losses in dynamic conditions), namely, that on the evaporator, which is pre-filled with 100 g butter, put on the coil and let it naturally air supplied into the oil. The air creates the bubbling oil, contributing to the evaporation of the oil, and the oxygen accelerates the oxidation. Heating oil is up to 250oC, time trials until 5 o'clock the Loss of oil is determined by the difference between its samples before and after the test.

The method has some limitations in the accurate assessment of the evaporation of oils during storage to the main of which are the following: the scavenger oil from the sample in the evaporation process is air, oxygen which promotes the oxidation of the oil, making it difficult to assess its evaporation; the method is applicable for a limited number of oils due to the high the present invention is to increase the reliability of the estimation of evaporation of mineral lubricating oils.

This goal is achieved by the fact that in the known method of estimating evaporation of lubricating oils by the loss of oil after heating the sample to a predetermined temperature with the simultaneous use of scavenger oil from the sample volume according to the present invention as a scavenger oil take N,N-dimethylformamide at a mass ratio to the oil sample 1:(1,9-2,1), and the heating is carried out until complete evaporation of the scavenger.

The essence of the method consists in the following. Studies have shown that the lubricating oils of various grades of viscosity it is difficult to reliably assess and differentiate them by evaporation due to the small evaporation losses in the absence of chemical reactions when the temperature control in the laboratory. When added to the oil as a scavenger N,N-dimethylformamide amount of evaporated oil increases significantly, while maintaining its chemical composition (table. 2).

N, N-dimethylformamide is known as a neutral solvent, which is miscible with water in any ratio, has a high dielectric constant, and therefore it has found wide application in gas-liquid chromatography, when conducting atomic-adsorption studies, elektricheska permeability 26,6

Vapor pressure, mm RT.article 3,7

Heat of vaporization (at TKip.), cal/g 137,8

Relative density 0,9445

The evaporation temperature,oC +153

N, N-dimethylformamide oil does not interact and do not dissolve.

This suggested the possibility of its use as a scavenger oil in assessing its evaporation.

In the proposed method of estimation of evaporation of oils, the oil is mixed with N, N-dimethylformamide in the form of an emulsion in a ratio of 1:(1.9 to 2.1), and evaporated under vacuum at a temperature of 1541oC (onset temperature of decomposition is most sensitive to high temperature additive DF-11 - dialkyl-dithiophosphate zinc +156oC) within 2 hours During this time the entire scavenger and part of the oil evaporates. For the test result accept the difference in sample mass of oil before and after evaporation.

Test was used to install the VA 624 Germany, consisting of a heating device; steel evaporating crucible with screw-on lid and a gas outlet tube, a block temperature control heating, vacuum pump, buffer tank and V-shaped manometer.

In the crucible of zastanowie 7-8 mm of water.article.

To determine the optimal ratio of oil and scavenger in the sample were prepared samples (table. 1), which were tested under conditions selected from oils of different classes viscosity (8, 10, 16 and 20 cSt).

The contents of N, N-dimethylformamide in the oil sample has established the following: 0; 1,0; 1,8; 1,9; 2,0; 2,1; 2,2; 3,0.

From table. 2 shows that the number of evaporated oil when tested without the scavenger (samples 1-1, 2-1, 3-1, 4-1) is significantly lower than when it is added to the oil sample. And the best result was obtained in a ratio of 1:(1,9-2,1) (samples 1-4, 1-5, 1-6, 2-4, 2-5, 2-6, 3-4, 3-5, 3-6, 4-4, 4-5, 4-6).

Studies have been carried out changing the chemical composition of the samples 1-5, 2-5, 3-5, 4-5, where the ratio of oil and scavenger 1:2, respectively (table. 3).

From table. 3 shows that the chemical composition of the oils after evaporation using as a scavenger oil N, N-dimethylformamide was not changed (change of alkaline and acid numbers within measurement error).

Comparative analysis of the present invention with the method of the prototype shows that the claimed method differs in that, first, as a scavenger oil by evaporation is used, the liquid N,N-dimethylformamide, and not the air; AI; thirdly, the evaporation temperature of the scavenger below the temperature of thermal decomposition of additives to oils, which excludes changes in the chemical composition of the oil by evaporation (table. 2).

Thus, the claimed method in accordance with p. 1 item 4 of the Law meets the criteria of patentability of the invention. This method is new, because the authors are not known sources as the patent and scientific and technical information (in addition to the above description analogs and prototypes), which would be represented by a set of distinctive features set forth in the claims.

The claimed method involves an inventive step, because the use of N,N-dimethylformamide as a scavenger oil by evaporation involves the use of completely different from those used currently in the industry of the properties of this fluid.

The method is implemented for 2 h, was tested and confirmed its effectiveness.

The method is industrially applicable, because involves the use of instruments and reagents available in sufficient quantities in the industry, and is recommended for wide application in the national economy, which uses mineral lubricating oil.


 

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