Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/26—Oils; Viscous liquids; Paints; Inks
  • G01N33/28—Oils, i.e. hydrocarbon liquids
  • G01N33/2888—Lubricating oil characteristics, e.g. deterioration
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/26—Conditioning of the fluid carrier; Flow patterns
  • G01N30/28—Control of physical parameters of the fluid carrier
  • G01N30/30—Control of physical parameters of the fluid carrier of temperature
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N2030/022—Column chromatography characterised by the kind of separation mechanism
  • G01N2030/025—Gas chromatography
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/26—Conditioning of the fluid carrier; Flow patterns
  • G01N30/28—Control of physical parameters of the fluid carrier
  • G01N30/30—Control of physical parameters of the fluid carrier of temperature
  • G01N2030/3007—Control of physical parameters of the fluid carrier of temperature same temperature for whole column
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
  • G01N30/02—Column chromatography
  • G01N30/88—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
  • G01N2030/8809—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample
  • G01N2030/884—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample organic compounds
  • G01N2030/8854—Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 analysis specially adapted for the sample organic compounds involving hydrocarbons

Definitions

• the invention generally relates to the analysis of lubricating oils, and in particular the determination of the fuel content in the oil of an internal combustion engine.
• fuel means any type of fuel used in the operation of internal combustion engines, such as, for example, gasoline, diesel, biofuels, etc.
• a chromatograph such as that shown in FIG. 1 is conventionally used, which comprises an injector 11 of the products to be analyzed, a column 12 for separating the products to be analyzed and traversed by a vector gas which facilitates elution. compounds, a detector 13 of said products.
• the separation column 12 is traversed at different speeds by the various compounds of the products to be analyzed.
• the detector 13 is for example a flame ionization detector known to those skilled in the art and has a flame supplied by the gases coming from the device 14.
• the detector 13 also receives a product transport gas in the separation column, for example hydrogen, helium or nitrogen.
• the detector 13 measures an intensity generated during the combustion of a compound derived from of column 12.
• the intensity generated varies depending on the presence or absence of a compound in the chamber.
• a chromatogram is generated to represent for example the intensity as a function of time.
• the use of such a chromatograph known to those skilled in the art, for determining the proportion of fuel (in particular diesel fuel) in a lubricating oil, allows to achieve a high accuracy in the results of the analyzes.
• a method implementing such a chromatograph has the following drawbacks: on the one hand a rise in temperature of the column too slow and on the other hand a cooling time of the same too large column, which increases the reaction time. occupation of the chromatograph by sample.
• the Applicant has developed a device for determining the proportion of fuel in a lubricating oil of a combustion engine, which overcomes these disadvantages through the use of a chromatograph comprising a chromatography column in a module. particular heating.
• the Applicant has also developed a method implementing such a device, wherein the column is subjected to determined cycles of temperature variation and pressure variation of the carrier gas in the column, which leads to results that are reliable, accurate and accurate.
• the present invention relates to a device for determining the proportion of fuel in a combustion engine lubricating oil, the lubricating oil containing an internal standard, and the lubricating oil. and the internal standard being diluted in a solvent to form a mixture to be analyzed, the device comprising a gas chromatograph which comprises:
• An injector of the products to be analyzed a separation column having an internal diameter ⁇ , a length L and a stationary phase, said separation column being fed with carrier gas,
• a heating module and a detector of said products
• the separation column comprises at least 22000 theoretical plates, with a statlonnaire phase occurring in the separation column in the form of a film at least 0.40 microns thick, this phase statlonnaire being fit separating the internal standard, the solvent, the fuel and the lubricating oil.
• the heating module is able to generate an increase in the temperature of the column at a speed of at least 350 ° C / min.
• the stationary phase is chosen from methylpolysiloxanes.
• the oven in which is generally integrated the chromatography column is replaced, in the device according to the invention, by a heating module located generally outside the oven, which is advantageously a linear heating module that can be arranged either along the column or around, for example in the form of a sleeve in which the column is inserted.
• a heating module allows climbs and descents temperature faster than is usually practiced, especially with a chromatograph whose separation column is in a conventional oven having a large volume, which generates a significant inertia to heating and cooling, which leads to a considerable reduction in analysis time.
• a heating module will be chosen which is not only able to heat the column at a speed up to at least 350 ° C / min, but which is also able to cool with a cooling speed at least equivalent.
• the heating module is advantageously constituted by a tubular heating resistor into which the column is inserted, it is possible to heat the column from room temperature to 35 ° C. at a speed of the order of 1000 ° C. min.
• the column may be associated with a cooling device such as a fan or a cold group, which allows an even faster cooling of the column, and in particular a cooling of 350 0 C at 30 0 C in a time equal to or less than 100 s.
• the carrier gas in the separation column can be helium, hydrogen or nitrogen.
• hydrogen is preferably used as a carrier gas because it makes it possible to obtain a better efficiency in terms of separation of the products.
• the separation column of the chromatograph has an internal diameter of 0.18 mm for a length of 10 m and a stationary phase thickness of 0.40 ⁇ m.
• the present invention also relates to a method for determining the proportion of fuel in a combustion engine lubricating oil using the device according to the invention.
• the column (12) is subjected to a thermal cycle comprising the following successive steps:
• A2) a rise in temperature to at least 350 ° C./min of ti up to the time t ⁇ r which is the time necessary for the optimization of the separation of the hydrocarbon compounds at C 20 from the fuel;
• step A3 a step at the temperature reached in step A2, from t 2 to time ts, which is the time required to optimize the separation of the hydrocarbon compounds from the oil and the C 2 s fuel ;
• the column is simultaneously subjected to a cycle of variation of the carrier gas pressure, which comprises the following successive stages: in the step Al between t 0 and t 1 , a bearing at an initial pressure pi;
• step A2) between t 1 and t 2 , an increase in the pressure of pi to a pressure P 2 at a speed of at least 40 kPa / min;
• step A5 • in step A5 after t4, a decrease in the pressure of p 3 to the initial pressure pi is achieved instantly; the nature and the thickness of the stationary phase having an influence on the durations of the different stages A1 to A5 and the values of the pressures Pi to P 3 .
• the determination of the proportion of gas oil in the oil comprises the following successive analysis steps: the formation of a mixture containing a sample of lubricating oil with analyze and an internal standard compound
• the second parameter C may be representative of at least a chromatograrrime area of the peak associated with a hydrocarbon compound C 20, C 21 / C 22 / C23, C24 or C 2 5 or their sum.
• the second parameter may be representative of the area of several peaks associated with respective hydrocarbon compounds belonging to the group of hydrocarbon compounds in (C 2 o ⁇ C 2 s).
• the coefficient C is advantageously corrected to reduce the concentration of the internal standard compound (C5) to a desired value.
• C can in particular be determined by the following formula:
• C 0 being the peak area associated with the internal standard (C 5 hydrocarbon compound)
• ⁇ being a correction coefficient towards a reference concentration
• - Cs being the concentration of the internal standard (C 5 hydrocarbon compound) in the sample.
• the formed mixture may further comprise a predetermined proportion of CS 2 carbon disulfide.
• the function of the carbon bisulphide is to dilute the entire mixture of the oil and the C 5 hydrocarbon compound in order to mix them homogeneously and to have a liquid and fluid medium whose separation is facilitated.
• CS 2 carbon disulfide is advantageously invisible to the detector, even in large quantities. Carbon bisulfide does not interfere with the detection of diesel and oil. However, other solvents can be selected, provided that their signal is taken into account in the final operation.
• the calibration line is preferably made beforehand with the same type of diesel and the same type of oil as in the sample to be analyzed, in order to refine the final accuracy to the maximum.
• a chromatogram of the standard mixture is established; a first parameter MO representative of the area of a peak of the chromatogram associated with the internal standard (C 5 hydrocarbon compound) is determined; a second parameter CO representative of the area of a peak of the chromatogram associated with a hydrocarbon compound representative of diesel fuel is determined,
• the constants a and b of the calibration line are determined.
• the constants a and b are obtained by taking as the calibration line the line that best corresponds to the different pairs formed (TO, CO / MO).
• FIG. 1 schematically illustrates an example of a chromatograph according to the state of the art:
• FIG. 2 schematically illustrates a separation column integrated in a tubular heating module which is used for implementing the method according to the invention
• FIG. 3 schematically illustrates a device according to the invention comprising a chromatograph with the separation column illustrated in FIG. 2.
• FIG. 2 shows a separation column 12 of the gas chromatograph used in the process according to the invention. This figure shows that the column 12 is integrated in a tubular heating module 120, which consists of a heating resistor.
• the equipment used for carrying out the process according to the invention comprises a gas chromatograph supplied with hydrogen (for example of N55 quality) and having a programming and a regulation accurate temperature and pressure in the column.
• This chromatograph comprises: "an apolar capillary column 12 marketed by the company RESTECH, which has a length of 10 meters and a diameter of 0.18 mm with a film thickness (stationary phase) of 0.4 ⁇ m; this column is integrated in a tubular heating resistor 120;
• FID flame ionization detector 13
• phase-free precolumn 16 connecting the detector 13 with the column 12, this precolumn being equipped with a union forming a junction with the capillary column 12;
• the apparatus illustrated in FIG. 2 differs from that of FIG. 3 by the use of an apolar capillary column having a length L of 10 m and a diameter of 0.53 mm with a film thickness of 1 ⁇ m. a ratio ⁇ / L of 5.3.10 ⁇ rj .
• a ratio ⁇ / L of 5.3.10 ⁇ rj .
• carbon disulfide CS2 such as that marketed by Prolabo with a Normapur quality for analysis
• used oils covering the entire range of targeted concentrations, for example from 0 to 10% by weight of diesel of this type.
• the sample is shaken vigorously for at least 10 minutes with a vibrating table to homogenize it.
• the standard samples are then subjected to the process described below for the samples to be analyzed.
• the samples to be analyzed are the following: - standard samples: E1, E2, E3, E4, each consisting of a mixture of new oil and gas oil, used oil samples containing estimated contents by weight of gas oil with respect to Sample weight, which are targeted in the desired range of concentrations to be analyzed.
• this mixture (sample + pentane) is almost immediately diluted by addition of solvent, 5 ml of CS 2 carbon disulphide, the flask containing the mixture obtained being sealed almost immediately so as to limit the evaporation of the CS 2 solvent;
• the resulting mixture is shaken by a vibrating table for approximately 1 minute to homogenize the mixture, and the mixture thus obtained is thus diluted to 75% by volume in CS2 and is ready to be injected into the chromatograph;
• the mixture obtained is poured into a 2 ml micro-flask so as to guarantee a minimum dead volume, which can be crimped onto the opening of the microfiole. fills as many micro-vials as necessary for a given mixture to be analyzed: "1 ⁇ l is injected by the automatic injector.
• the carrier gas in the separation column is hydrogen, and the column is subjected, from the deposition of a sample to be analyzed in the column, to the thermal cycles and following hydrogen pressure variation: comprising successively:
• cycle thermal device comprising successively:
• the temperature of the injector is controlled to follow the temperature program with 10 0 C in advance, according to the principle of oven tracking (oven track type in English).
• the flow rate of the carrier gas in the column is conditioned by that imposed by the helium pressure program and the chromatograph operates in pressure regulation.
• the injector is of the flow divider type and the temperature at its level is kept constant at 320 ° C.
• the flow of hydrogen in the detector is of the order of 30 ml / min and the air flow rate in this detector is of the order of 400 mpm to 10 ml / min.
• the integration times of the various compounds are adjusted according to the aging of the column and controlled with the reference solution.
• the obtained chromatograms are analyzed to extract the areas of the peaks associated with the various compounds.
• AO be the area extracted for the pentane internal standard
• Al being the area associated with carbon disulfide and at the beginning of the gas oil up to C 20 excluded
• A2 being the associated area up to an excluded € 22
• A4 being the associated area up to C 24 excluded
• A5 being the associated area up to € 2 s excluded.
• the pentane standard concentration is reduced to an imposed value. It will thus be possible to calculate a relative area of the various compounds (or family of compounds), whatever the chromatographic conditions.
• the corrected area AO is calculated as follows:
• the diesel content is determined by the following formula:
• oils may have a particular structure (for example when Ci 6 is present in the mixture), a particular integration may be required.
• Such an integration can in particular exclude the area of the peak corresponding to the compound in question and requires a specific calibration.
• the temperature and pressure profiles of the chromatograph are corrected periodically as a function of standards on a solution containing the Cs, C 2 O-C 26 and C 30 hydrocarbon compounds.
• the invention 0.19% 0. 80% 0. 38% 0. 65%
• Table 1 shows that it is possible to obtain with the method according to the invention "MURDIG" results as reliable and accurate as with the method of the prior art, and more quickly. Indeed, for an equivalent reliability and precision, the duration of the analysis is 6 minutes and 30 seconds if using the method of the invention, instead of 2 hours with the method of the prior art, which has the consequence that a single analysis is carried out in two hours with the process of the invention, but eighteen analyzes with the method according to the invention.

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• Oil, Petroleum & Natural Gas (AREA)
• Medicinal Chemistry (AREA)
• Food Science & Technology (AREA)
• General Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
• Lubrication Details And Ventilation Of Internal Combustion Engines (AREA)

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• 2007
  • 2007-07-09 FR FR0704967A patent/FR2918753B1/fr not_active Expired - Fee Related
• 2008
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