What are the hazards of sulfur hexafluoride 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 to the atmospheric environment?

发布时间：2018-04-26 来源：ydlcb 浏览次数：48次

Sulfur hexafluoride (SF6) is a colorless, odorless, odorless, non-toxic inert non-flammable gas. Pure sulfur hexafluoride gas is non-toxic, but not life-sustaining. Sulfur hexafluoride is a simple asphyxiant, and exposure to an atmosphere with oxygen content of less than 19.5% can cause dizziness, coma, increased drooling, unresponsiveness, nausea, vomiting, loss of consciousness and even death. Exposure to an atmosphere with an oxygen content of less than 12% will cause unconsciousness without warning and the ability to self-rescue. In its production process or under the action of high energy factors, it will decompose and produce a number of toxic or even highly toxic, highly corrosive harmful substances, such as SF4, SOF2, SF2, SO2F2, HF, etc. are toxic and highly corrosive compounds, which are very harmful to the human body. SF6 gas molecules are potentially harmful to the greenhouse effect, because the impact of one SF6 gas molecule on the greenhouse effect is equivalent to that of 23,900 CO2 molecules, and CO2 gas can be converted into oxygen and released into the atmosphere through plant photosynthesis. The SF6 gas emitted into the atmosphere can neither be broken down nor converted, resulting in a very long atmospheric life of about 3,200 years. Today, about 21 billion CO2 gases are released into the atmosphere each year, and the SF6 gas released into the atmosphere each year is equivalent to 125 million tons of CO2 gas. Therefore, the impact of SF6 on the greenhouse effect is huge.

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. Among them, 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. 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.

The greenhouse effect of sulfur hexafluoride is the main point of the harm of sulfur hexafluoride, in addition, SF6 decomposition is also one of the causes of sulfur hexafluoride harm. Although the chemical properties of pure SF6 gas are stable, safe and non-toxic, under the action of high temperature and high pressure arc, if there is still excessive water, it is possible to break down hydrofluoric acid (HF) and toxic SOF2, SO2F2, SF4 and SOF4 and other low-cost sulfur fluoride, under the action of high temperature arc, It will also decompose sulfur dioxide (SO2) and hydrofluoric acid (HF), which produce one of the greenhouse gases. These toxic gases will not only corrode the equipment itself, but also cause serious harm to the human body once leakage occurs. The toxic breakdown of SF6 is also a hazard of sulfur hexafluoride.

According to statistics, the annual demand for gas in the domestic power industry is about 8,000 tons, and the annual waste rate is 10%, and the emissions are equivalent to 20 million tons of CO2 gas. With the rapid development of the power industry and the improvement of technical equipment, the demand for SF6 gas is currently rising rapidly.

Because sulfur hexafluoride gas is easy to decompose with oxygen and water under the action of electric arc, many toxic and harmful and corrosive substances such as sulfuryl tetrafluoride, hydrofluoric acid and sulfur dioxide are produced, and these decomposition substances have different degrees of harm to high pressure equipment and personal safety.

Although China has issued a series of standards and regulations on the production, management and application of sulfur hexafluoride gas, such as "sulfur hexafluoride gas management and detection Guidelines in electrical equipment", "High voltage switching equipment sulfur hexafluoride gas seal test guidelines", "sulfur hexafluoride electrical equipment Operation, test and maintenance personnel safety protection rules", etc. However, due to the lack of understanding of the greenhouse effect of sulfur hexafluoride gas by maintenance personnel, the lack of on-site purification treatment equipment and the confusion of the use and management of sulfur hexafluoride gas, the phenomenon of arbitrary emission of sulfur hexafluoride gas in maintenance often occurs.

According to reports, although the current recovery and charging equipment on the market has the so-called purification function, there are problems such as slow recovery speed, large gas loss, oil content, gas quality cannot be guaranteed, and it cannot be processed in the warehouse after recovery. At the same time, China's standard requirements for refilled gas according to the country, with a miniaturized gas treatment system and detection room purification treatment center project can meet the development needs of China's power market, so that sulfur hexafluoride gas to achieve a true sense of recycling. The sulfur hexafluoride gas was recovered and the waste sf6 gas was purified to reach the national standard.

1. Excessive moisture will harm insulation, affect arc extinguishing, and produce toxic substances. When the water content of the circuit breaker is high, it is easy to condensation on the surface of the insulation material, resulting in insulation decline, and flashover breakdown occurs in serious cases.

2. Gas with high water content is decomposed under the action of electric arc, sulfur hexafluoride gas and water produce a variety of hydrolysis reactions, resulting in tungsten trioxide, copper fluoride and other powder insulation, of which copper fluoride has a strong moisture absorption, attached to the insulation surface, so that the flashover voltage along the surface drops, hydrofluoric acid, sulfuric acid and other strong corrosion, corrosion effect on solid organic materials and metals. The equipment life is shortened. The harm of sulfur hexafluoride gas moisture is not only for the equipment, in fact, the excessive moisture will also lead to SF6 gas and the toxic decomposition produced under the action of high temperature arc discharged into the atmosphere, damaging the body and harming the environment.