A kind of qualitative and quantitative analysis SF
6The method of gas discharge decomposition product
Technical field
The invention belongs to the analyzing and testing field, be specifically related to a kind of qualitative and quantitative analysis SF
6The method of gas discharge decomposition product.
Background technology
SF
6Gas has the good characteristics of stable chemical nature, safety non-toxic, insulation and arc extinction performance at normal temperatures, and it is used in various electrical equipments widely as a kind of good insulating medium.Yet, along with the electric equipment operation time increases, various insulation fault problems will appear, be characterized in before the device interior insulating medium is puncturing, shelf depreciation not occuring.
SF
6The generation subfluoride will occur to decompose, the O in these inferior stable materials and equipment in gas under the effect of shelf depreciation
2Perhaps H
2O further reacts and generates SO
2F
2, SOF
4, SOF
2, SO
2, H
2S, S
2F
10O, HF, CF
4Deng product.Wherein, acidic materials SO
2, H
2S, HF have corrosive attack, destroy material and cause dielectric strength to descend, and then cause industrial accident.
For shelf depreciation, traditional detection method such as electrical measuring method, ultrasonic method are subjected to on-the-spot electromagnetic interference (EMI) serious, the impact judgement.By analyzing SF
6Kind and the concentration of discharge decomposition product can be understood the device interior state of insulation, for fault diagnosis provides an effective foundation.At present, both domestic and external studies show that, the shelf depreciation that the different insulative defective causes, SF
6There is difference in the discharge decomposition product on kind and generating rate.Therefore, need to seek a kind of effective qualitative and quantitative analysis method, identification SF as much as possible
6The discharge decomposition product, this is significant to accurate judgement insulation fault.
At present, analyze SF
6The common method of gas discharge decomposition product is vapor-phase chromatography, infra-red sepectrometry.But there are the following problems in actual applications for these methods:
1) analysis result is not comprehensive.Utilize vapor-phase chromatography to SF
6The detection of discharge decomposition product, the selection of chromatographic column is even more important, and its effective separation to target compound has determined follow-up qualitative and quantitative analysis.In the IEC60480-2004 standard, suggestion adopts Porapak Q packed column to separate, but (Fig. 1) can find out from the feature spectrogram, SO
2F
2Retention time and SF
6Close, both go out the peak simultaneously, can not realize separating fully.Simultaneously, this pillar can not detect other decomposition products such as SOF
4And H
2S。And if request for utilization number is 201010134902.6 " a kind of SF that analyze in electrical equipment
6The method of decomposition product " the Gas Pro chromatographic column of recommending in patent, although can realize SO
2F
2With SF
6Separate, but SOF
2Easily change into SO in pillar
2And can't detect, and it is to SOF
4Detection also helpless.
2) accurate qualitative being not easy.Adopt vapor-phase chromatography that unknown sample is analyzed, qualitative process need is compared retention time and known substance calibrating gas, thereby determines the unknown sample composition.If without calibrating gas or some composition goes out the peak jointly, can give the accurately qualitative difficulty that causes.
3) quantitatively there is mutual interference.Vapor-phase chromatography can only be carried out integral and calculating to complete separation peak shape, and testing process is separated each target compound fully as failing, and the peak shape partial stack overlaps even fully can't accurate quantitative analysis, exists each other and disturbs.
4) detection limit is not enough.Infra-red sepectrometry detects SF
6The discharge decomposition product, although need not to separate various components, its detection limit is higher than vapor-phase chromatography, can't detect the product of lower concentration.
Summary of the invention
The purpose of this invention is to provide a kind of can multianalysis and accurate qualitative, quantitative SF
6The combined gas chromatography mass spectrometry analytical approach of gas discharge decomposition product.
To achieve these goals, technical scheme of the present invention is: a kind of qualitative and quantitative analysis SF is provided
6The method of gas discharge decomposition product, key step comprises:
1) sampling;
2) utilize gas chromatography-GC-MS to carry out qualitative and quantitative analysis to sample, detecting device is the quadrupole rod mass detector, chromatographic column adopting CP-Sil 5 CB capillary columns.
Described step 2) the CP-Sil 5 CB chromatographic columns of selecting, its parameter is: length is 60m, and thickness is 8 μ m, and internal diameter is 0.32mm.
Preferably, described step 2) analytical approach, analysis condition is as follows, carrier gas: high-purity He gas (99.9999%); Post case temperature: initial 40 ℃-60 ℃, final 150
℃-220
℃; Heating rate: 5
℃/min-20 ℃/min; Post flow: 0.9mL/min-1.2 mL/min; Purge flow rate: 3 mL/min.
Described step 2) analytical approach is analyzed SF
6The gas discharge decomposition product, its setting parameter is:
1. chromatographiccondition is as follows:
Carrier gas: high-purity He gas (99.9999%),
Sampling volume: 300 μ L,
Post case temperature: 40
℃ constant temperature keeps 7min, with 15
℃/min speed is warming up to 220
℃, keep 1min,
Injector temperature: 200
℃,
The sample introduction pattern: shunting,
Split ratio: 10,
Flow control mode: constant linear velocity,
Pressure: 56.1kPa,
Post flow: 1.2mL/min,
Purge flow rate: 3.0mL/min;
2. mass spectrophotometry condition is as follows:
Ion source temperature: 200 ℃,
Interface temperature: 250
℃,
The detector switch time: after beginning to detect, 2.9min opens in the time, and 4.02min closes in the time, and 4.26min opens in the time, and 7min closes in the time,
Detecting device acquisition mode: SIM,
Gather quasi-molecular ions: comprise that mass-to-charge ratio is 69,50,119,44,83,102,105,86,67,48,34,33,64,66 quasi-molecular ions.
Described step 2) analytical approach is synchronously utilized retention time and with reference to the ion identification target compound, is set retention time deviation range ± 0.069min, sets with reference to Ion Phase strength variance value 80%.
Described step 2) SF
6Discharge analyte analyzing and testing comprises: sample introduction; After beginning to detect, at SF
6Before going out the peak, analyze CF
4, C
2F
6(time period 2.9min-4.02min); Treat SF
6Go out the peak complete, reopen detecting device, Analysis for CO
2, SO
2F
2, SOF
4, SOF
2, H
2S, SO
2(time period 4.26min-7min).
Described step 2) analytical approach, the quantitative employing external standard method of target compound is set up typical curve corresponding to " concentration-peak area ", optional zero crossing in typical curve linear fit process, calculate peak area according to integrating meter, then calculate the target compound concentration value by typical curve.For the C that can't purchase calibrating gas
2F
6, adopt relative C
3F
8Correction factor is that 1.0 modes are carried out sxemiquantitative.
Described step 2) analytical approach, it is as follows that the quantitative test of all types of target compound detects lower limit:
Table 1 SF
6The quantitative analysis method of gas discharge decomposition product detects lower limit
Gas composition |
CF
4 |
CO
2 |
SO
2F
2 |
SOF
4 |
SOF
2 |
H
2S
|
Minimum inspection limit (μ l/l) |
0.6 |
0.1 |
0.3 |
0.4 |
0.2 |
0.6 |
Annotate: adopt semiquantitative C
2F
6, and detection is subjected to the residual SO that affects of chromatographic column
2, detect lower limit and can't determine.
After the present invention adopts technique scheme, mainly contain following advantage:
1) the detected components kind is comprehensive.Single injected sampling adopts SF
6Discharge decomposition product analytical approach can detect CF
4, C
2F
6, CO
2, SO
2F
2, SOF
4, SOF
2, SO
2, H
28 kinds of components such as S.Testing process only needed to complete in 20 minutes, increased work efficiency, and reduced energy consumption.Detect material comprehensive, help fully to understand the inside electric appliance state of insulation, accurately failure judgement.
2) to the unknown sample fast qualitative.Need not to buy calibrating gas, utilize known compound in detected ion collection of illustrative plates and standard spectrum storehouse to compare to realize qualitative.Utilize simultaneously retention time and with reference to the ion relative intensity, accurately in judgement sample, whether target compound exists.
3) accurate quantitative analysis.For treating the quantification compound, selected good object ion peak through after qualitative confirmation, only need to carry out integration to the specific objective quasi-molecular ions that collects, and can calculate concentration from typical curve.Even if two kinds even the retention time of multiple compounds is close, as long as select different object ions peaks to carry out integral and calculating to different compounds, can carry out accurate quantitative analysis equally.Compare with gas chromatography, eliminated overlap of peaks cause can't be quantitative impact.
Description of drawings
Fig. 1 carries out the resulting typical color spectrogram of gas chromatographic detection for adopting the Porapak Q packed column of advising in existing IEC60480-2004 standard.
Fig. 2 is SF of the present invention in embodiment
6The testing result of gas discharge decomposition product analysis method.
Embodiment
The described analysis of the present embodiment SF
6The gas chromatography-mass spectrography method of gas discharge decomposition product comprises the following steps:
1) sampling.For fear of the absorption of sampling container material to test sample, can adopt the sampler bag that the Tedlar material is made to gather gaseous sample.During collection, the material of connecting line adopts teflon or stainless steel as far as possible.Before each sampling, utilize vacuum pump that sampler bag is vacuumized, remove other gaseous impuritieies; Connecting line can purge and vacuumize with tested gas.The present embodiment adopts certain domestic SF
6Sample gas after gas process 96h shelf depreciation, and the people is for adding a certain amount of CF
4, H
2S is with the validity of verification method.
2) adopt Shimadzu gas chromatograph-mass spectrometer (GCMS) (GCMS-QP2010) that sample is detected.Select CP-Sil 5 CB chromatographic columns, its parameter is: length is 60m, and thickness is 8 μ m, and internal diameter is 0.32mm.If the short separating effect of chromatogram column length is bad.Use high-purity He gas as carrier gas; Pin sample introduction, sampling volume are 300 μ L.
1. set chromatographic condition:
Post case temperature: 40 ℃ of constant temperature keep 7min, with 15
℃/min speed is warming up to 220 ℃, keeps 1min; Injector temperature: 200
℃; The sample introduction pattern: shunting, split ratio is 10; Flow control mode: constant linear velocity; Pressure: 56.1kPa; Post flow: 1.2mL/min; Purge flow rate: 3.0mL/min.
2. set the mass spectrum condition:
Ion source temperature: 200
℃; Interface temperature: 250
℃; The detector switch time: after beginning to detect, 2.9min opens in the time, and 4.02min closes in the time, and 4.26min opens in the time, and 7min closes in the time, selects the SIM type collection; Gather quasi-molecular ions: comprise that mass-to-charge ratio (m/z) is 69,50,119,44,83,102,105,86,67,48,34,33,64,66 quasi-molecular ions.
3) qualitative analysis is adopted retention time and with reference to the ion identification compound, is set retention time band ± 0.069min, sets with reference to Ion Phase strength variance value 80%.
4) quantitative test to the characteristic ion peak integration of target compound, is drawn the peak area substitution external standard method that obtains " concentration-peak area " typical curve of gained, target compound concentration in calculation sample.
Fig. 2 is for utilizing said method to detect SF
6The result of gas discharge decomposition product.In figure, the corresponding compound of each quasi-molecular ions is followed successively by CF
4, C
2F
6, CO
2, SO
2F
2, SOF
4, SOF
2, H
2S, SO
2, each content is:
Above disclosed is only preferred embodiment of the present invention, certainly can not limit with this interest field of the present invention, and the equivalent variations of therefore doing according to claim of the present invention still belongs to the scope that the present invention is contained.