Oxygen, or O2, which comprises 21 percent of the earth's atmosphere, supports life and makes combustion possible. The most abundant of all elements on earth, oxygen comprises 85 percent of its oceans and, as a component of most rocks and minerals, 46 percent of its solid crust. In addition, it constitutes 60 percent of the human body.
Colorless, odorless and tasteless, oxygen has poor solubility in water. A specific gravity of 1.105 makes it slightly heavier than air. When cooled to its boiling point of -297o F (-183o C), oxygen becomes a transparent, pale blue liquid that is slightly heavier than water.
Oxygen reacts with all elements, except inert gases, to form compounds called oxides. The rate of reaction - known as oxidation - varies. For example, magnesium oxidizes very rapidly, igniting spontaneously in air. However, noble metals, such as gold and platinum, oxidize only at very high temperatures.
Although oxygen itself is nonflammable, it enhances combustion and enables all materials that are flammable in air to burn much more vigorously. These combustion-supporting properties account for its use in many industrial applications.
Production of Oxygen
Oxygen, the second-largest volume industrial gas, is produced commercially as a gas or as a liquid by several methods. These include:
|Cryogenic Air separation, a process that compresses and cools atmospheric air, then, - relying on different boiling points - separates the resulting liquid into its components in a distillation column|
|Vacuum Pressure Swing Adsorption (psa), a non-cryogenic technology that produces oxygen from air by using an adsorbent in a pressure swing process to remove nitrogen.|
Oxygen is used in diverse applications covering many industries, including:
|Steel Manufacturing: to enrich air and increase combustion temperatures in blast and open hearth furnaces; to raise steel temperatures and enhance recycling of scrap metal in electric arc furnaces; and to replace coke as the combustible in steel making.|
|Chemical Processing: to alter the structure of feed stocks through oxidation, producing nitric acid, ethylene oxide, propylene oxide, vinyl chloride monomer and other building block chemicals; and to increase capacity and destruction efficiency of waste incinerators.|
|Pulp and Paper: to help manufacturers meet stringent environmental regulations in a variety of mill processes including delignification, bleaching, oxidative extraction, chemical recovery, white/black liquor oxidation and lime kiln enrichment.|
|Metal Production: to replace or enrich air, increasing combustion temperatures in ferrous and non-ferrous metals production; to create a hot flame in high-temperature welding torches used in cutting and welding.|
|Metal Fabrication: to support oxy-fuel cutting operations. Sometimes added in small quantities for shielding gases.|
|Glass Manufacturing: to enhance combustion in glass furnaces and forehearths, reducing nitrogen oxide (NOx) emissions to levels below new stringent requirements of the U.S. Clean Air Ac.|
|Petroleum Recovery and Refining: to reduce viscosity and improve flow in oil and gas wells; to increase capacity of fluid catalytic cracking plants as well as to facilitate use of heavier feed stocks; and to reduce sulfur emissions in refineries.|
|Health Services: to resuscitate or, in combination with other gases, to anesthetize; but also essential to life-support systems used in emergencies or long-term treatment of patients with respiratory disorders.|
|Utilities: to convert coal to electricity for power generation.|