SF6 gas has a history of one hundred years. It is an artificial noble gas synthesized by two French chemists, Moissan and Lebeau in 1900. Around 1940, the US military used it for the Manhattan Project. SF6 is a strong electronegative gas. Its molecules can easily absorb free electrons to form large negative ions, which weaken the collision ionization process in the gas. Therefore, its electrical insulation strength is very high, which is about 2.5 times the air insulation strength in a uniform electric field. . The thermal decomposition peak of SF6 gas appears at t≈2000K. Therefore, when the AC arc current crosses zero, the cooling effect of SF6 on the arc is much stronger than that of air, and its arc extinguishing capacity is about 100 times that of air. Because SF6 gas has excellent arc extinguishing performance and insulation performance and good chemical stability, it has been used as the arc extinguishing medium of high-voltage circuit breakers since the end of the 1950s. In UHV and UHV circuit breakers, SF6, as an arc extinguishing medium, has replaced oil and has largely replaced compressed air.
Since the mid-1960s, SF6 has been widely used as an insulating medium for high-voltage electrical equipment. SF6 gas-insulated fully enclosed switchgear has a much smaller footprint than conventional open high-voltage power distribution devices, and its operation is not affected by external weather and environmental conditions, so it is not only widely used in ultra-high voltage and ultra-high voltage power systems, And has begun to be used in power distribution networks (SF6 gas insulated switchgear and ring network power supply units). The advantages of SF6 gas-insulated pipeline transmission lines are low dielectric loss, large transmission capacity, and can be used in high-drop occasions, so they are often used in hydropower station outlets to replace conventional oil-filled cables. SF6 gas insulated transformer has the advantages of fire and explosion protection. This kind of distribution transformer is especially suitable for power supply in densely populated areas and high-rise buildings. SF6 gas-insulated ultra-high voltage transformers have been successfully developed, and fully gas-insulated substations will be a direction for the development of substation technology.
Chemically stable. Slightly soluble in water, alcohol and ether, soluble in potassium hydroxide. Does not react chemically with sodium hydroxide, liquid ammonia and hydrochloric acid. Does not react with copper, silver, iron, and aluminum in a dry environment below 300°C. Below 500℃, it has no effect on quartz. It reacts with metallic sodium at 250°C, and reacts in liquid ammonia at -64°C. It will be decomposed when mixed with hydrogen sulfide and heated. At 200°C, in the presence of certain metals such as steel and silicon steel, it can promote its slow decomposition. Because the density of sulphur hexafluoride is almost five times that of air, people who inhale sulphur hexafluoride will speak with longer wavelengths and lower frequencies, and their speech will become as powerful as a man, while helium is the opposite. After inhalation, the wavelength becomes shorter and the frequency becomes higher, and the voice becomes thin and weak like a woman.
Physical data Properties: Colorless and odorless gas. Melting point (℃): -51 Boiling point (℃): -64 (sublimation) Relative density (water = 1): 1.67 (-100°C) Relative vapor density (air=1): 6.602 Saturated vapor pressure (kPa): 2450 (25°C) Critical temperature (℃): 45.6 Critical pressure (MPa): 3.76 Octanol/water partition coefficient: 1.68 Solubility: slightly soluble in water, soluble in ethanol and ether Heat of vaporization (Kg/mol): 23.59 (heat of sublimation) Heat of fusion (Kg/mol): 5.82 Viscosity (mPa·s, gas): 0.01576 Viscosity (mPa·s, liquid): 0.277 Refractive index (gas): 1.000783
Sulfur hexafluoride (SF6) compressor-products have the advantages of compactness and simple structure, no oil, no leakage, light weight and small size. Similar to motors, long-life lubricated and sealed roller bearings can greatly reduce friction in the crank mechanism. Therefore, there is no oil in the entire compressor. Given enough focus, using small manufacturing tolerances and high-tech materials, such compressors are not only economical but also very reliable. When process gas is used in the production process, smoke and leakage may be generated during the production process. This makes the production process and process technology tend to use closed-loop systems with gas. The cost saved by the equipment can recover the equipment investment cost in a short time. Such as:
★Inert gases, such as xenon, argon or helium, sulfur hexafluoride (SF6); ★SF6 (sulfur hexafluoride) gas in power system; ★Leakage of natural gas in large-scale compression system; ★Inert gas processing to purify nitrogen; ★Extract carbon dioxide from supercritical CO2 process ★Leakage gas accumulated during processing, such as carbon monoxide (CO), sulfur hexafluoride (SF6)
The media that the sulfur hexafluoride compressor can compressor are: sulfur hexafluoride, helium, nitrogen, biogas, propylene, tail gas, wellhead gas, coal gas, coal bed gas, methyl chloride, ethylene, LNG, butadiene, R22 refrigeration Agent, ethane, butane, liquefied gas, etc.
