What are the hazards of sulfur hexafluoride (SF6) to the atmospheric environment?- SF6在线监测系统_SF6检漏仪_SF6传感器_SF6密度继电器

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What are the hazards of sulfur hexafluoride (SF6) to the atmospheric environment?

发布时间：2017-02-15 来源：ydlcb 浏览次数：48次

SF6 gas has a century-old history, it is two French chemists Moissan and Lebeau synthetic artificial inert gas in 1900, around 1940, the United States military used it for the Manhattan Project (nuclear military).

Since the mid-1960s, SF6 has been widely used as an insulating medium for high-voltage electrical equipment. SF6 gas-insulated switchgear covers a much smaller area than conventional open-type high-voltage distribution devices, and its operation is not affected by external meteorological and environmental conditions, so it is not only widely used in ultra-high voltage and UHV power systems, but also has begun to be used in distribution networks (SF6 gas-insulated switchgear and ring network power supply units). SF6 gas insulated pipeline transmission line has the advantages of low medium loss, large transmission capacity, and can be used in high drop occasions, so it is often used in hydropower station outlet, replacing conventional oil-filled cables. SF6 gas insulated transformer has the advantages of fire and explosion protection, this distribution transformer is especially suitable for densely populated areas and high-rise building power supply. SF6 gas insulated ultra-high voltage transformer has been successfully developed, and all gas insulated substation will be a direction of the development of power transformation technology.

In the last hundred years, the earth's climate is undergoing a significant change with global warming as the main feature. This global warming is caused by both natural climate fluctuations and the greenhouse effect, which is enhanced by human activities. Reducing greenhouse gas emissions and mitigating climate change is the main goal of the United Nations Convention on Climate Change and the Kyoto Protocol, but China is facing more and more international pressure in reducing greenhouse gas emissions. The greenhouse effect means that gases such as carbon dioxide in the atmosphere can heat up the Earth's surface through short-wave radiation from the sun. At the same time, it blocks the Earth's surface from emitting long-wave radiation into space, thus warming the atmosphere. Because this role of carbon dioxide and other gases is similar to the role of "greenhouse", it is called "greenhouse effect", and carbon dioxide and other gases are called "greenhouse gases". At present, it is found that there are six kinds of greenhouse gases emitted by human activities, they are carbon dioxide, methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, among which three kinds of fluoride. CO2 has the greatest impact on the greenhouse effect. The effect of sulfur hexafluoride (SF6) gas is only 0.1%, but sulfur hexafluoride (SF6) gas molecules have potential harm to the greenhouse effect, because the impact of sulfur hexafluoride (SF6) gas molecules on the greenhouse effect is 25,000 times that of CO2 molecules, at the same time, emissions in the atmosphere Sulfur hexafluoride (SF6) has a long gas life of about 3400 years. Today, about 21 billion CO2 gases are released into the atmosphere each year, and sulfur hexafluoride (SF6) gas is equivalent to 125 million tons of CO2 gas.

SF6 is a strongly electronegative gas, and its molecules are easy to adsorb free electrons and form heavy negative ions, weakening the collision ionization process in the gas, so its electrical insulation strength is very high, about 2.5 times the strength of air insulation in a uniform electric field. SF6 gas has a thermal decomposition peak at t≈2000K, so when the AC arc current crosses zero, SF6 has a much stronger cooling effect on the arc than air, and its arc extinguishing ability is about 100 times that of air. Because SF6 gas has excellent arc extinguishing and insulation properties and good chemical stability, it has been used as an arc extinguishing medium for high voltage circuit breakers since the late 1950s. In ultra-high voltage and UHV circuit breakers, SF6, as an arc extinguishing medium, has replaced oil and has largely replaced compressed air

More than half of the approximately 8,500 tonnes of sulfur hexafluoride (SF6) gas produced globally each year is now used in the power industry. In the power industry, high-voltage switchgear occupies more than 80% of the gas. The gas consumption of the medium voltage switch accounts for about 1/10; Mainly used in 126 ~ 252kV high pressure, 330 ~ 800kV ultra-high pressure field, especially 126kV ~ 252kV ~ 550kV circuit breaker (GCB), sulfur hexafluoride (SF6) closed combination electrical appliances (GIS), inflatable cabinet (C-GIS) ), sulfur hexafluoride (SF6) gas insulated pipe bus bar (GIL). Therefore, the reasonable and correct use and management of sulfur hexafluoride (SF6) gas has reduced emissions to the point where it must be regulated.

Sulfur hexafluoride is an asphyxiant that, at high concentrations, causes difficulty breathing, wheezing, blue skin and mucous membranes, and systemic convulsions. After inhaling a mixture of 80% sulfur hexafluoride and 20% oxygen for a few minutes, the human body will experience numbness in the limbs and even suffocation.

Second, the decomposition of sulfur hexafluoride gas under the action of electric arc, such as sulfur tetrafluoride, sulfur fluoride, sulfur difluoride, thionyl fluoride, sulfur difluoride, thionyl tetrafluoride and hydrofluoric acid, etc., they have strong corrosion and toxicity.

1, sulfur tetrafluoride: colorless gas at room temperature, with pungent odor, in the air can produce smoke with moisture, has an impairing effect on the lung, affecting the respiratory system, its toxicity and phosgene equivalent.

2, sulfur fluoride: at room temperature is a colorless gas, toxic, pungent odor, the respiratory system has a similar damage to phosgene.

3, sulfur difluoride: chemical properties are extremely unstable, after heat performance is more active, easy to hydrolyze into sulfur, sulfur dioxide and hydrofluoric acid.

4, thionyl fluoride: colorless gas, rotten egg taste, chemical stability, highly toxic gas, can cause serious pulmonary edema, so that animals suffocate to death.

5, sulfuryl difluoride: colorless odorless gas, chemical properties are extremely stable, is a toxic gas that can cause convulsions. Its risk is that it has no pungent smell and does not cause irritation to the nasal mucosa, so it is often found that after poisoning, it will die quickly.

6, tetrafluorothionyl: colorless gas, has a pungent smell, has an infringing effect on the lungs.

7, hydrofluoric acid: acid is the most corrosive substance. It has a strong irritating effect on the skin and mucous membrane, and can cause pulmonary edema and pneumonia.

Leakage emergency treatment: quickly evacuate the contaminated area to the upper wind, and isolation, strictly restrict access. It is recommended that emergency personnel wear self-contained positive pressure breathing apparatus and general work clothes. Cut off the source of leakage as much as possible. Reasonable ventilation to accelerate diffusion. Use immediately if possible. The leak container should be properly disposed of, repaired and inspected before use.