氦helium
主要性质
化学式 He
分子量 4.003
气体密度 0.1786g/L（0°C、1atm）
液态密度 0.1250kg/・（沸点）
比重 0.14（空气=1）
沸点 4.3K（1atm）
熔点 1.0K（26atm）
临界温度 5.3K
临界压力 0.228MPa
蒸发热 5.50cal/g、20.4kJ/kg（沸点）
液态与气态的体积比 699（0℃、1atm、以液态体积为1・）
氦气为无色无味，不可燃气体，空气中的含量约为百万分之5.2。化学性质完全不活泼，通常状态下不与其它元素或化合物结合。在室温和大气压力下，氦是无色、无味的气体。它在干空气中的体积含量为5.24×10-6。
氦不能仅靠将饱和液体冷却到绝对零度而固化。要使氦固化，必须施以相应压力。在2.173K，氦将或多少从正常液体转变成一种具有独特性质的流体。温度高于2.173K的液体称为氦Ⅰ。低于此温度的液体称为氦Ⅱ。氦Ⅱ为超流体。它的熵为零，热导率极高，黏度几乎为零。氦是单原子气体，化学性质不活泼。通常条件下不与其它元素和化合物反应。
发现
早在1868年，法国天文学家简森(Janssen P J C,1824-1907)在观察日全蚀时，就曾在太阳光谱上观察到一条黄线D，这和早已知道的钠光谱的D1和D2两条线不相同。同时，英国天文学家洛克耶尔(Lockyer J N,1836-1920)也观测到这条黄线D。当时天文学家认为这条线只有太阳才有，并且还认为是一种金属元素。所以洛克耶尔把这个元素取名为Helium，这是由两个字拼起来的，helio是希腊文太阳神的意思，后缀-ium是指金属元素而言。中译名为氦。
1895年，莱姆赛和另一位英国化学家特拉弗斯(Travers M W,1872-1961)合作，在用硫酸处理沥青铀矿时，产生一种不活泼的气体，用光谱鉴定为氦，证实了氦元素也是一种稀有气体，这种元素地球上也有，并且是非金属元素。
理论上可以从空气中分离抽取，但因其含量过于稀薄，工业上从含氦量约为0.5%的天然气中分离、精制得到氦气。
氦，HELIUM，源自helios，意为"太阳"，1868年发现。几乎世界上所有的氦气都是由美国的天然气井中提取的。它比空气轻，广泛地应用于飞艇和气球，以取代其有高度可燃性的氢气。液态氦因其沸点特别低而成为低温学领域的无价之宝。
氦气的用途
利用其－268.9℃的低沸点，液氦可以用于超低温冷却。在悬浮列车等领域中广受关注的超导体应用中，氦气是不可或缺的。此外，由于化学性质不活泼和轻于空气等特征，氦气常用于飞船或广告气球中的充入气体，这一用途也是众所周知的。在海洋开发领域的呼吸用混合气体中，以及医疗领域的核磁共振成像设备的超导电磁体冷却的用途中，氦气都得到广泛的应用：军工、科研、石化、制冷、医疗、半导体、管道检漏、超导实验、金属制造、深海潜水、高精度焊接、光电子产品生产等。
氦气冷冻机，核磁共振，谱仪，光谱
氦气传播速度
因为氦气传播声音的速度差不多为空气的三倍，所以吸入氦气的人说话的声音会变高频率。这个有趣的现像，使得吸入氦气的人说话尖声细气，男性顿时会变得娘娘腔，就好像旧时的卡通人物一样。
过度使用所产生的问题
需要注意的是，如果大量吸入氦气，会造成体内氧气被氦取代，因而发生缺氧(呼吸反射是受体内过量二氧化碳驱动，而对缺氧并不敏感)，严重的甚至会死亡。 另外，如果是由高压气瓶中直接吸入氦气，那么其高流速就会严重地破坏肺部组织。 大量而高压的氦和氧会造成高压紧张症状 High pressure nervous syndrome (HPNS)，不过少量的氮就能够处理这个问题。
氦气是国防军工和高科技产业发展不可或缺的稀有战略性物资之一。含氦天然气迄今仍是工业化生产氦气的唯一来源。我国氦气资源相当贫乏，含量很低，提取难度大，成本高。因此，在保护有限氦气资源的同时，研究开发先进的天然气提氦技术对于提高氦气生产的经济性、保障国家用氦安全和促进我国天然气提氦工业的发展具有重要意义。通过对目前提氦技术的分析介绍，低温冷凝法较为成熟，但能耗、成本较高；吸附法、吸收法和膜渗透法等其他提氦技术各具特点，但目前限于适用条件尚不能规模化工业应用。随着新材料、新技术的发展，天然气提氦技术不断改进创新，吸附法、膜渗透法等提氦工艺发展迅速，联产法、联合法工艺有着良好的应用前景，这些都为促进天然气提氦技术的发展提供了新的思路。
天然气提氦工业现状及意义
天然气提氦采用低温冷凝法从氦含量仅为0．2 的天然气中单纯提氦的成本较高。氦气由于在卫星飞船发射、导弹武器工业、低温超导研究、半导体生产等方面具有重要的用途，因而我国对氦气的需求量越来越大，
世界氦气资源状况
在所发现的天然气中，有些氦气含量可高达8左右，而大多数含量低于2 。即使是这类氦气含量很低的天然气，由于比空气中氦气含量高上千万倍，因此仍是目前世界上氦气的主要来源，
天然气提氦主要方法
1．吸附法
这种方法是根据天然气中各组分在固体吸附剂表面上吸附能力的差异而将其中的氦分离出来。限于吸附剂的吸附容量，吸附法一般适用于杂质含量小于1O 的粗氦精制中。近年来发展起来的变压吸附(PSA)即属于此类改进型。
2．吸收法
选用适当的吸收溶剂 ，在一定的条件下可将沸点比氦气高的天然气中的其余组分洗涤吸收除去而提取氦气。所用的吸收溶剂如液态氟烃、液态烷烃等。
3．扩散法
利用氦气所具有的高的热扩散性能，可将天然气中的氦气浓缩提取出来。所用的扩散元件通常为石英玻璃毛细管，管壁厚度为0．025～0．127 mm，内径与壁厚之比为3～7，操作温度在400～500。C，操作压力按具体操作条件可以在几十兆帕到数百兆帕范围内选用。经石英玻璃毛细管扩散提取的氦气纯度相当高，但因所采用的石英玻璃毛细管极细，制作不便，操作时又需要在高温和相当高的压差下进行，因此用扩散法规模化提氦尚存在许多限制。
4．膜渗透法
随着膜材料的发展，膜渗透法提氦展现出越来越好的应用前景。各种气体对膜具有一定的渗透性能，且各种气体的渗透性能各不相同，因而可以利用渗透法将天然气中的氦气提取出来。工业上应用的渗透膜应具有：渗透常数大，以保证产量并减少所需的膜面积；分离因子大，使流程简化；化学、机械和热的稳定性好，以保持长期的使用性能。膜材对天然气各组分渗透的选择性可用分离因子口"来表示。
5．低温冷凝法
本方法是目前各国从天然气中提取氦气广泛采用的方法。通常由气源预处理净化、粗氦提取及氦气精制等工序构成。
(1)含氦天然气预处理净化
含氦气源中的H S、CO。、水分，甚至汞等杂质在进入低温装置前须净化处理，以免在低温下使管道、阀门和设备产生堵塞、腐蚀和恶化工艺条件。常用的酸气脱除方法有：醇胺法、热钾碱法、砜胺法。提氦工艺对天然气中H。S、CO。残留量要求是：H2s≤4 ppm[1 ppm—M／22．4(mg／m。)，M 为分子量，下同]，CO。≤ 100 ppm。鉴于提氦效益考量，应优选有利于降低提氦成本的脱除方法。脱水工艺方法：天然气提氦一般选择分子筛来精脱水，脱水深度要求小于1 ppm，同时进一步吸附脱除残余酸性气体。脱汞工艺方法：HgSIV脱汞分子筛可以再生并循环使用，但设备和控制复杂；而浸硫活性炭不能循环使用，需定期更换，但设备和操作简单。
(2)粗氦提取
天然气经二次冷凝后制得氦含量为6o ～7o的粗氦，冷凝所需冷量由常压液甲烷、常压液氮或负压液甲烷供给。一次冷凝要求无乙烷以上的馏分，二次冷凝要求甲烷含量小于1 。同时釜液液烃中的氦含量要小于10 ppm，以提高氦气回收率。
(3)氦气精制
天然气中较难液化的氢随着氦气的提浓被浓缩在粗氦中，需要在精制前将其除去。工业上一般采用催化氧化脱氢法，储氢合金等脱氢工艺也在发展中。小于10 ppm 的残留氢在其后的高压冷凝吸附过程中与氮、少量的甲烷等其他杂质同时除去。冷源一般由常压液氮提供，可制得纯度99．99 以上的氦气。其他精制法如洗涤吸收法，甲烷、丙烷等天然气组分均可作为吸收剂。
helium
Main Properties
Chemical formula He
Molecular weight 4.003
Gas density 0.1786g / L (0 ° C, 1atm)
Liquid density 0.1250kg / · (boiling point)
Specific gravity 0.14 (Air = 1)
The boiling point of 4.3K (1atm)
Melting point 1.0K (26atm)
The critical temperature of 5.3K
Critical pressure 0.228MPa
Evaporation heat 5.50cal / g, 20.4kJ / kg (boiling)
Liquid and gaseous volume ratio of 699 (0 ℃, 1atm, in a liquid volume of 1 ·)
Helium is a colorless, odorless, non-flammable gases in the air content of about 5.2 ppm. Chemical properties that are completely inactive, not in combination with other elements or compounds under normal status. At room temperature and atmospheric pressure, helium is a colorless, odorless gas. It is the volume of content in the dry air of 5.24 × 10-6.
It not only by the saturated liquid is cooled to absolute zero and cured. To solidify helium, it must be subjected to the appropriate pressure. In 2.173K, helium or how much from the normal liquid transformed into a fluid with unique properties. Temperature is higher than 2.173K liquid called helium Ⅰ. Below this temperature, the liquid called helium Ⅱ. For the superfluid helium Ⅱ. Its entropy is zero, high thermal conductivity, viscosity is almost zero. Helium is a monatomic gas, chemically inert. Under normal conditions it does not react with other elements and compounds.
Find
As early as 1868, French astronomer Jenson (Janssen PJC, 1824-1907) in the observation of a total solar eclipse, once in the solar spectrum observed a yellow line D, D1 and already know which of two sodium spectrum and D2 lines are not the same. Meanwhile, the British astronomer Lockyer (Lockyer J N, 1836-1920) also observed this yellow line D. Astronomers believe that this line was only the sun only, and is also considered to be a metal element. So this element Lockyer named Helium, which is put together by the word, helio is the meaning of the Greek sun god, the suffix -ium means in terms of metal element. The translation of helium.
In 1895, Lyme tournament and another British chemist Travers (Travers MW, 1872-1961), in cooperation when treated with sulfuric acid pitchblende, resulting in a non-reactive gas, spectroscopic identification of helium, It confirmed that helium is a rare gas element on this planet there, and is non-metallic elements.
In theory, it can be separated from the extracted air, but its content is too thin, the industry of 0.5% from natural gas containing helium is about separation and purification to obtain helium.
Helium, HELIUM, from helios, meaning "sun", discovered in 1868. Almost all the world's helium gas wells by the United States are extracted. It is lighter than air, airships and balloons are widely used to replace its highly flammable hydrogen gas. Especially because of its low boiling point of liquid helium becomes invaluable in the field of cryogenics.
The use of helium
Using its low boiling point -268.9 ℃, it can be used for ultra-low temperature liquid helium cooling. In the suspension train in areas such widespread attention superconductor applications, helium is indispensable. Further, since the chemically inert and lighter-than-air and other features commonly used in spacecraft or helium advertising balloon filled with gas, is also well known for this purpose. Breathing in ocean development in the field of gas mixtures, as well as the medical field magnetic resonance imaging apparatus superconducting electromagnets cooling applications, helium has been widely used: the military, scientific research, petrochemical, refrigeration, medical, semiconductor, pipe leak, superconductivity experiments, metal manufacturing, deep sea diving, precision welding, and other optoelectronic products.
Helium refrigerator, nuclear magnetic resonance spectrometer, spectrum
Helium propagation velocity
Because helium spread almost three times the speed of sound in the air, so people inhale helium voice becomes high frequencies. This fun is like, so that the suction helium speak shrill thin air, men will suddenly become a sissy, just like the old cartoon characters the same.
Overuse problems arising
Note that, if a large number of inhaled helium, oxygen the body can cause substituted helium, thereby causing hypoxia (breathing reflex is driven by the body of excess carbon dioxide, and is not sensitive to hypoxia), severe and even death. In addition, if it is inhaled directly from the high-pressure helium gas cylinder, its high flow rates will seriously damage lung tissue. A large number of high-pressure helium and oxygen can cause high pressure nervous symptoms High pressure nervous syndrome (HPNS), but a small amount of nitrogen will be able to deal with this problem.
Helium is one of the rare strategic materials for national defense and high-tech industries indispensable. Containing helium gas so far remains the only source of industrial production of helium. Our helium resources fairly poor, low levels of extraction difficult and costly. Thus, while protecting the limited resources of helium, the research and development of advanced gas technology to improve mention helium helium production economy, national security significance helium security and promote the development of China's natural gas extract helium industry. He mentioned by the current technical analysis reports, cryogenic condensation is more mature, but higher energy costs; adsorption, absorption of other mention helium technology and membrane permeation method different characteristics, but is currently limited to the applicable conditions still can not scale chemical applications. With the development of new materials, new technologies, helium gas lift technology continues to improve and innovate, adsorption, membrane permeation method mentioned helium technology developed rapidly, cogeneration, combined method technology has good prospects, which are mentioned for the promotion of natural gas helium technology development provides a new way of thinking.
Mention helium gas industry status quo and significance
Low-temperature helium lifting gas condensation method only 0.2 higher natural gas costs in a simple mention of helium from helium content. Since helium in satellite launch of the spacecraft, missiles aspects arms industry, low temperature superconductivity research, semiconductor manufacturing has important uses, thus of growing demand for helium,
World Helium Resources
Found in natural gas, some helium content of up to about 8, and most content of less than 2. Even low levels of these helium gas, due to the high content of helium in the air than a million times, it is still the main source of helium in the world at present,
The main method of helium gas lift
1. Adsorption
And wherein the method is that helium gas is separated based on differences in the ability of the components adsorbed on the solid adsorbent surfaces. Limited adsorption capacity of the adsorbent, the adsorption method is generally applicable to purifying crude helium impurity content of less than 1O. In recent years, developed a pressure swing adsorption (PSA) that is part of such a modification.
2. Absorption
Selection of suitable absorption solvent, under certain conditions can be washed with a boiling point of helium is extracted helium gas in a high ratio of absorption to remove the remaining components. Used as the absorbing solvent liquid fluorocarbons, liquid paraffin and the like.
3. Diffusion method
Helium has the advantage of high thermal diffusivity, natural gas can be helium concentrate extracted. Diffusion element generally used quartz glass capillary tube, wall thickness of 0.025 ~ 0.127 mm, an inner diameter to wall thickness ratio of 3 to 7, the operating temperature of 400 to 500. C, operating pressure according to the specific operating conditions can be selected in the range of tens to hundreds of MPa MPa range. After a silica glass capillary diffusion extract helium purity is very high, but the fine quartz glass capillary used to produce inconvenience, operation time and need to be at a high temperature and relatively high pressure, hence the large-scale diffusion method mentioned helium there are still many restrictions.
4. Membrane permeation method
With the development of membrane materials, membrane permeation method mentioned helium exhibits better and better prospects. Gases of films having a certain permeability, and the permeability of various gases are different, which can be extracted from natural gas utilizing helium permeation method. Industrial application of membrane should have: permeability constant large to ensure production and reduce the amount of membrane area; large separation factor, the flow is simplified; chemical, mechanical and thermal stability, in order to maintain long-term performance. Permeable membranes for selective component of natural gas available for each separation factor of mouth "to represent.
5. Cryogenic condensation
This method is a method to extract the current national helium from natural gas is widely used. Usually by the pre-treatment cleaning gas source, crude helium extraction and refining processes constituted helium.
(1) containing helium gas pre-treatment cleaning
Containing helium source H S, CO. , Water, and even mercury and other contaminants before entering the cryogenic purification apparatus shall, at a low temperature in order to avoid the pipe, valves and equipment clogging, corrosion and deterioration of the process conditions. Acid gas removal methods commonly used are: alkanolamines, hot potassium alkali, sulfone amine method. It mentioned the process of natural gas H. S, CO. Residues requirements are: H2s≤4 ppm [1 ppm-M / 22.4, M is the molecular weight, the same below (mg / m.)], CO. ≤ 100 ppm. Given the mention helium benefit considerations should preferably help to reduce the cost of removal mention helium method. Dehydration process methods: mentioning helium gas generally choose to fine sieve dehydration, the desired depth of less than 1 ppm, and further removal of residual acid gas adsorption. Mercury Removal Process Method: HgSIV Demercuration molecular sieve can be regenerated and recycled, but the equipment and control complex; activated carbon and sulfur dip can not be recycled, to be regularly replaced, but the simple equipment and operation.
(2) crude helium extraction
Gas condensate obtained by the second after the helium content of crude helium 6o ~ 7o, the cold liquid from the atmospheric methane, liquid nitrogen at atmospheric pressure or vacuum condensate liquid methane supply needed. No more than primary-condensed ethane fraction, the secondary condensate claim methane content of less than 1. Meanwhile kettle liquid helium liquid hydrocarbon content to less than 10 ppm, in order to improve the recovery of helium.
(3) purified helium
Liquefied natural gas is more difficult to concentrate hydrogen with helium is concentrated in the crude helium, we need purification before it is removed. General industrial catalytic oxidative dehydrogenation, hydrogen storage alloy, the dehydrogenation process are also developing. Less than 10 ppm of residual hydrogen in the subsequent condensation of the high pressure during the adsorption and simultaneous removal of nitrogen and small amounts of methane and other impurities. Atmospheric cold source generally provided by liquid nitrogen, can be obtained over a purity of 99.99 helium. Other purification methods such as washing absorption, methane, propane, natural gas and other components can be used as absorbent. |
