The way the differentiated determination of oxidation inhibitors in transformer oils

 

(57) Abstract:

The invention relates to research performance properties of petroleum products, namely the determination of oxidation inhibitors in transformer oils (TM) and can be used to determine the timing of replacement or upgrade of oils. Transformer oils are oxidized in a mixture of cumene in the presence of initiator azobisisobutyronitrile (AIBN), measure the amount of oxygen consumed from time to time, determine the induction period, the total content of oxidation inhibitors (C mol/kg) is found by the formula , where Wi- the rate of initiation 6,810-8mol/Ls; R - hanging oil, kg/l; - the total induction period, with the content of BHT (CAND, wt.%) determine the range of absorption in the infrared region 3550 - 3800 cm-1and calculated according to the formula CAND= 2,6116 D-0,024, where D is the optical density, and the number of newly formed oxidation inhibitors (Cx, wt. %) is found from the expression . Possible to increase the accuracy of the analysis. 1 table, 3 Il.

The invention relates to the field of research performance properties of petroleum products, namely the determination of oxidation inhibitors in transformer oils (TM), and can EOW oxidation in TM impose anti-oxidation additive BHT (2,6-ditretbutyl-4-METHYLPHENOL) in an amount of 0.2 to 0.7 wt.%. In addition, during operation, storage TM, under the influence of temperature, electromagnetic fields, solid insulating materials, air oxidation and other external factors in the oil produced products with antioxidant properties (resins, asphaltenes and other) and hinder the analysis of antioxidant additives BHT.

A known method of determining the content of BHT in TM using thin-layer chromatography [HOWTO manual transformer oils. The method of thin-layer chromatography to determine the content of BHT in transformer oil. RD 3443, 105-189]. This method only allows a qualitative assessment of the content of BHT in TM.

The closest is the method of determining the content of BHT in TM by oxidation of oil in a mixture with cumene in the presence of initiator azobisisobutyronitrile [Patent N 2121142. The method of determination of BHT in transformer oil /Pisarev, S. I., Panchenkov C. I., N. Yudina.In., BI N 30, 1998].

However, the known method is not sufficiently accurate for the differentiated determination of BHT and newly oxidation inhibitors (nie), especially in cases where their reactionary actively sterowanego quantitative determination of BHT and newly oxidation inhibitors in TM.

The technical result is achieved by the fact that TM oxidized in a mixture of cumene in the presence of initiator azobisisobutyronitrile (AIBN), measure the amount of absorbed oxygen from time to time, build a graph, determine the total induction period, count the total number of oxidation inhibitors (C), the content of BHT (CAND) is determined by a calibration curve and the IR spectrum of the investigated oil absorption band 3660 cm-1and the difference are the number of newly formed oxidation inhibitors (Cx)

Cx= C - CAND< / BR>
Example 1. 33,0 mg TM1, 10.1 mg of the initiator AIBN and 10 ml of cumene is placed in a reaction vessel connected with gasometrical installation, and with constant stirring at a temperature of 60oC measure the amount of absorbed oxygen in time. Build a dependency graph of the amount of oxygen from time to time, determine the induction period (Fig. 1). The content of oxidation inhibitors is determined by the formula

,

where Wi- the speed of initiation of 6.8 10-8mol/l;

P - linkage of the sample TM1, kg/l (subject to 10 ml of solvent).

The content of oxidation inhibitors, wt.%, determined by the formula

< / BR>
Cof ionol= a 9.09 the s inhibition stabilizers using model chain reaction. "Kinetics and catalysis". T. XVII, V. 6, 1977, S. 1395-1403].

To identify ionol determine the reactivity of the additives7ratio

,

where [O2] is the concentration of absorbed oxygen;

[RH]0the concentration of cumene, 7,14 mol/l;

K3the rate constant for the continuation of the chain of 1.75 mol/lsec;

t - time, s;

- the induction period, in seconds.

To determine the tg of the kinetic curve is represented in coordinates

< / BR>
(semi-log anamorphosis) (Fig. 2).

On a semi-logarithmic anamorphosis seen 1 site.

TO7= 2.210-4l/Mols.

The IR spectra of TM removed on the spectrophotometer SPECORD M 80 in the range of wave numbers 3550 - 3800-1cm with spectral slit width = 6 cm-1. TM is poured into the cell of NaCl thickness 0,395 mm BHT has a characteristic absorption band in the infrared region of 3660 cm-1. To construct the calibration curve was used TM with different known concentrations of BHT. As a measure of the intensity of the bands was selected optical density at the maximum absorption of this band:

,

where D is the optical density;

I is the intensity of radiation transmitted through TM;

dispositions, and then built the dependence D = f(CAND) (Fig. 3), which after processing by the method of least squares was used to determine the CANDin TM. The magnitude of the accuracy of the approximation is equal to 0,9832. The equation of a straight line, used to calculate the CAND: CAND= 2,6116 D - 0,024.

In the IR spectrum in the range of wave numbers 3550-3800 cm-1for TM1 determine the optical density D, then a calibration curve to find the content of BHT in TM1, equal to 0.36 wt.%. The results of the content analysis of oxidation inhibitors in TM1 using the kinetic method and IR spectroscopy are shown in table.

Thus, in oil TM1 only contains antioxidant additive BHT and both methods allow to determine its content with high accuracy.

Example 2. Differential determination of oxidation inhibitors in TM2 carried out analogously to example 1. The determination results are presented in the table. Kinetic method determined the total content of the oxidation inhibitors of 0.13 wt. %. Spectral - 0.07 wt.%. The difference is explained by the contribution of newly formed inhibitors with reaction activity, equal to the reaction activity of BHT. Thus, in TM2 contains inhibitors of origivation oxidation in TM carried out analogously to example 1. The determination results are presented in the table. The content of BHT determined by the method of IR-spectroscopy, equal to 0.14 wt. %, kinetic 0.11 wt. %. The difference in the content of BHT is explained by the contribution of BHT in the newly formed oxidation inhibitors reactivity, close to the reactivity of ionol. Thus, in TM contains C = 0.23 wt.%, CAND= about 0.14 wt.%, Cx= 0.09 wt.%.

Example 4. Differential determination of oxidation inhibitors in TM carried out analogously to example 1. The determination results are presented in the table. The content of BHT determined by the method of IR-spectroscopy, equal to 0.12 wt. %, kinetic - 0.09 wt.%. The difference in the content of BHT is explained by the contribution of BHT in the newly formed oxidation inhibitors with reaction activity, similar to the reaction activity of BHT. Thus, in TM contains C = 0,29 wt.%, CAND= to 0.12 wt.%, Cx= to 0.17 wt.%.

The proposed method allows for a more accurate comparison with the known method differentiated quantitative assessment of the content of BHT and newly oxidation inhibitors in TM.

The way the differentiated determination of oxidation inhibitors in the transformer wt is erenia volume of oxygen consumed depending on time, determination of induction period and the content of BHT, characterized in that the total content of oxidation inhibitors (C mol/kg), are according to the formula

< / BR>
where Wi is the rate of initiation of 6.8 10-8mol/l;

P - hanging oil, kg/l;

- the total induction period, with,

determine the optical density, the content of BHT (CAND, wt.%) determine the range of absorption in the infrared region 3550 - 3800 cm-1and calculated according to the formula

WITHAND= 2,6116 D - 0,024,

where D is the optical density, and the number of newly formed oxidation inhibitors (Cx, wt.%) found from the expression

.

 

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FIELD: investigating or analyzing materials.

SUBSTANCE: method comprises determining the values of the inform-parameter for various reference petrols, plotting calibration dependence of the inform-parameter on the octane number, determining the value of the inform-parameter of a sample of petrol to be analyzed, determining octane number of the petrol to be analyzed from the calibration curve, and measuring density and temperature of the sample. The value of the inform-parameter is determined from measuring the surface tension of the sample. The octane number is calculated within temperature range 10-40oC.

EFFECT: enhanced accuracy of determining.

1 tbl cl, dwg

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