Methods of Preparation
1, condensation: natural gas helium extraction in the industrial condensation method The process includes natural gas pretreatment and purification, crude helium production and helium refining and other processes, the production of 99.99% pure helium.
2, air separation method: the general use of condensation method from the air device to extract crude helium, neon mixture of crude helium, neon mixture of pure helium, neon mixture of separation and purification, 99.99% pure helium.
3, hydrogen liquefaction method: industrial hydrogen liquefaction method from the ammonia tail gas helium. The process is low-temperature adsorption to remove nitrogen, distillation to get crude helium plus oxygen catalyzed dehydrogenation and helium purification to produce 99.99% pure helium.
4, high purity helium method: 99.99% pure helium will be further purified by activated carbon adsorption to produce 99.9999% high purity helium.
Precautions
1, the pressure is usually 15MPa, the use of YQY-12 or 152IN-125 and other pressure reducers should be used after the decompression, the use of soapy water before the use of the gas pipeline leak detection to ensure that the gas pipeline does not leak.
2, to ensure that helium does not leak, the workplace to maintain ventilation, when the helium content increases resulting in the oxygen content of less than 19.5%, the patient first appeared to accelerate respiration, inattentiveness, ****济失调; followed by fatigue and weakness, restlessness, nausea, vomiting, coma, convulsions, so that death.
3, each bottle of helium gas in the use to the end of the gas, should be retained in the bottle residual pressure in the 0.5MPa, the minimum shall not be less than 0.25MPa residual pressure, should be closed to the bottle valve, in order to ensure the quality of the gas and the use of safety.
4, bottled helium in the transportation and storage, use should be classified and stacked, are not allowed to be close to open flames and heat sources, should not be close to the fire, do not dip the oil and wax, do not expose to the sun, do not throw, do not hit, it is strictly prohibited in the gas cylinder body arc or arc, is strictly forbidden to barbaric loading and unloading, the helium cylinder should be used in the short distance movement of the cylinder trolleys, the long-distance movement of cylinders should be used in the transportation of hazardous materials transportation vehicles. The temperature of liquid helium is 4.25K, which can cause serious frostbite in contact with skin.
5, helium storage cylinder use and inspection in accordance with the State Bureau of Quality and Technical Supervision "Cylinder Safety Supervision Regulations," the provisions of the cylinder filling pressure shall not exceed the prescribed pressure. Safety cap should be installed at any time, a protective valve, the cylinder every three years inspection (except in special circumstances) to do the appearance of the inspection and hydrostatic test, the test is qualified before continuing to use, the test in the inflatable unit.
Introduction of helium, the English name Helium, symbol He, colorless, odorless, non-flammable gas, the air content of about 5.2 parts per million. chemically inactive, the usual state of the other elements or compounds do not combine. 1908, July 10, the Dutch physicist Onnes first liquefied helium.
History
As early as 1868, the French astronomer Janssen P J C (1824-1907), while observing a total eclipse of the sun, had observed a yellow line D on the sun's spectrum, which was not the same as the two lines D1 and D2 of the long known sodium spectrum. At the same time, the British astronomer Lockyer J N (1836-1920) also observed this yellow line D. At that time, astronomers thought that this line is only the sun, and also thought that it is a metal element. So Lockyer named the element Helium, which is a combination of two words, helio, which is the Greek word for sun god, and the suffix -ium, which refers to the metal element. The Chinese translation is helium.
In 1895, Lemsey, in collaboration with another British chemist, Travers M W (1872-1961), was treating pitchblende uranium ore with sulphuric acid when an inactive gas was produced, which was identified spectroscopically as helium, confirming that helium is also a rare gas, which is found on Earth, and that the element helium is a non-metallic element.
Physical properties
At room temperature and atmospheric pressure, helium is a colorless, odorless gas. Its volume content in dry air is 5.24 x 10-6. It is the substance with the lowest critical temperature discovered by man. It appears dark yellow when subjected to a low-pressure discharge.
Helium cannot be cured simply by cooling a saturated liquid to absolute zero. For helium to solidify, a corresponding pressure must be applied. At 2.173 K, helium will change, more or less, from a normal liquid to a fluid with unique properties. Liquids with temperatures above 2.173 K are called helium I. Liquids below this temperature are called Helium II. Helium II is a superfluid. It has zero entropy, extremely high thermal conductivity and almost zero viscosity.
Because of the low temperature of liquid helium, when certain metals or metal compounds are cooled with liquid helium, the electrical resistance of the metal or metal compound disappears completely, a phenomenon known as superconductivity, and this temperature is called the critical temperature.
Because helium transmits sound almost three times as fast as air, a person who inhales helium speaks at a higher frequency. This interesting phenomenon makes people who inhale helium speak in a shrill voice, as if they were old-time cartoon characters.
Chemical properties
Helium is a monatomic gas and is chemically inactive. Helium generally does not produce compounds, and can form He+2, HeH plasma and molecules when excited in a low-pressure discharge tube.
Applications
Helium is widely used in military, scientific research, petrochemical, refrigeration, medical, semiconductor, pipeline leakage detection, superconductivity experiments, metal manufacturing, deep-sea diving, high-precision welding, and production of optoelectronic products.
1, low-temperature cold source: using liquid helium's low boiling point of -268.9℃, liquid helium can be used for ultra-low temperature cooling. And the ultra-low temperature cooling technology in the superconducting technology and other fields have a wide range of applications, superconducting materials need to be in the low temperature (100K or so) in order to show superconducting properties, most of the time only the liquid helium can be relatively easy to realize such extremely low temperature. Superconducting technology has large applications in the transportation industry for magnetic levitation trains and in the medical field for nuclear magnetic **** vibration imaging equipment.
2, balloon inflation: because helium density is much smaller than air (air density of 1.29kg/m3, helium density of 0.1786kg/m3), and the chemical nature of the extremely inactive, safer than hydrogen (hydrogen can be burned in the air, may cause an explosion), helium is commonly used in airships or advertising balloons in the filling gas.
3, inspection and analysis: instrumental analysis of commonly used nuclear magnetic **** vibration analyzer superconducting magnets need to use liquid helium cooling, gas chromatography analysis of helium is often used as a carrier gas, the use of helium permeability is good, non-combustible characteristics of helium, helium is also used in vacuum leak detection, such as helium mass spectrometry leak detector.
4, protective gas: the use of helium inactive chemical properties, helium is commonly used in magnesium, zirconium, aluminum, titanium and other metal welding protective gas.
6, other aspects: helium can be used as a high-vacuum devices, atomic nuclear reactors in rockets, spacecraft used to transport liquid hydrogen, liquid oxygen and other liquid propellants pressurized gas. Helium is also used as a cleaning agent for atomic reactors, in the field of marine development of breathing with a mixture of gases, gas thermometer filling gas, etc..