Method for detecting non-anode effect CF4

A detection method and anode effect technology, applied in the measurement of color/spectral characteristics, etc., can solve the problems of unable to detect non-anode effect, difficult to detect non-anode effect spectrum, affecting the detection accuracy of equipment, etc.

Inactive Publication Date: 2012-06-13
GUIZHOU BRANCH CHINA ALUMINUM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, non-anode effect CF cannot be detected with existing PFC detection methods 4 The main problems are: (1) The CF used in the existing PFC detection method 4 The sensitivity range of spectral analysis is 10-100ppmv, and the detection equipment cannot identify the extremely low concentration of non-anode effect CF 4 Spectrum; (2) The sampling points of the existing PFC detection method include the flue gas of multiple electrolyzers, which dilutes the non-anode effect CF 4 The concentration makes it difficult for the detection eq

Method used

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  • Method for detecting non-anode effect CF4
  • Method for detecting non-anode effect CF4
  • Method for detecting non-anode effect CF4

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Set the PFC detection sampling point 3 on the cigarette pipe 2 of a certain 400kA electrolytic cell 1, insert the flue gas sampling pipe 4 (as attached figure 1 shown); connect the detection equipment, moisture filter, dust filter, sampling tube, sampling pump, monitoring computer; start the detection equipment, set the maximum CF of the detection equipment 4 The standard spectrum is 1ppmv, calibrate the zero point of the equipment, adjust the flue gas flow into the detection equipment; monitor the voltage change of the electrolytic cell, when the cell voltage exceeds the normal operating voltage by 50 millivolts, start detection and record CF 4 During the test period, keep the tank cover in an airtight state, and the gas collection efficiency of the electrolyzer flue gas should not be lower than 90%. After continuous detection for 6 hours, CF was detected 4 The average concentration of 0.707ppmv.

Embodiment 2

[0031] Set the PFC detection sampling point 3 on the cigarette pipe 2 of a certain 300kA electrolytic cell 1, insert the flue gas sampling pipe 4 (as attached figure 1 shown); connect the detection equipment, moisture filter, dust filter, sampling tube, sampling pump, monitoring computer; start the detection equipment, set the maximum CF of the detection equipment 4 The standard spectrum is 1ppmv, calibrate the zero point of the equipment, adjust the flue gas flow into the detection equipment; monitor the voltage change of the electrolytic cell, when the cell voltage exceeds the normal operating voltage by 50 millivolts, start detection and record CF 4 During the test period, keep the tank cover in an airtight state, and the gas collection efficiency of the electrolyzer flue gas should not be lower than 90%. After 9 hours of continuous detection, CF was detected 4 The average concentration of 0.516ppmv.

Embodiment 3

[0033] Set the PFC detection sampling point in the gas collecting hood 7 of the middle seam / side seam of the anode of a certain 200kA electrolyzer; connect the detection equipment, moisture filter, dust filter, sampling pipe, sampling pump, monitoring computer; start the detection equipment, set Determine the maximum CF of the testing equipment 4 The standard spectrum is 1ppmv, calibrate the zero point of the equipment, adjust the flue gas flow into the detection equipment; monitor the change of the anode current density of the electrolytic cell, when the current density of individual anodes 6 (connected by the guide rod 5) (one or several anodes) exceeds the normal Operating current density 0.5A / cm 2 , insert the flue gas sampling pipe 4 for sampling (as attached figure 2 shown), start detection, record CF 4 The volume concentration; if there are multiple anodes, multiple sampling points can be used to collect the gas together for detection. After 12 hours of continuous d...

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Abstract

The invention discloses a method for detecting non-anode effect CF4, which comprises a sampling point which is obtained by sampling electrolytic tank flue gas on a gas pipe of the electrolytic tank, a tank cover plate of the electrolytic tank is kept in a sealed state, the gas collection efficiency of the flue gas in the electrolytic tank is not less than 90%, a detection device spectral analysis sensitizing zone is corrected, therefore the volume concentration of the CF4 spectral analysis sensitizing zone is in 0-1ppmv scope; the dust in flue gas is removed before the flue gas is introduced in the detection device, a drying agent is used for absorbing the moisture in flue gas; the detection device is started, the zero point of the device is calibrated, and the flue gas flux in the detection device is regulated, voltage change and anodic current density change of the electrolytic tank are monitored, when the voltage of the electrolytic tank exceeds normal operation voltage by 50 millivolts or anodic current density exceeds normal operation current density by 0.5A/cm<2>, the detection is started, and the volume concentration of CF4 is recorded. The method of the invention can detect the non-anode effect CF4 with extreme low concentration and reach the purpose of quantitative analysis of the non-anode effect CF4.

Description

[0001] technical field [0002] The invention belongs to the field of electrolytic aluminum greenhouse gas emission reduction, in particular to a non-anode effect CF 4 detection method. Background technique [0003] In the production process of electrolytic aluminum, the electrolytic reaction in normal production is the carbon thermal reduction reaction of alumina to generate aluminum and emit CO 2 . But during the "anode effect" of the electrolyzer, the electrolyzer produces two fluorocarbons: carbon tetrafluoride (CF 4 ) and dicarbon hexafluoride (C 2 f 6 ), collectively referred to as perfluorocarbons (PFCs). Its formation reaction is as follows: [0004] Na 3 AlF 6 +3 / 4C=3 / 4CF 4 +Al+3NaF (E=2.55V) [0005] Na 3 AlF 6 +C=1 / 2C 2 f 6 +Al+3NaF (E=2.68V) [0006] CF 4 and C 2 f 6 The lifetimes of the two compounds are as high as 50,000 years and 10,000 years respectively, and they have extremely high global warming potential (GWP), which belongs to strong gr...

Claims

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Application Information

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IPC IPC(8): G01N21/25
Inventor 李旺兴陈喜平赵庆云邱仕麟罗丽芬
Owner GUIZHOU BRANCH CHINA ALUMINUM IND
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