Oxygen, which makes up 21 percent of the earth's atmosphere, supports life and makes combustion possible. The most abundant of all elements on earth, oxygen accounts for 85 percent of the earth's 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.
Oxygen reacts with all elements, except noble 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.
Chemical formula: O2
Purity level: ≥ 99.5%
Relative density (air = 1): 1.1
Aspect: colourless gas
Odour: odourless gas
Limit of flammability in air: not applicable
Other properties: poor solubility in water
Oxygen is used in several applications, which are listed below.
Food and beverage
In food and beverage, oxygen is used:
- for modified atmosphere packaging
- to breed and transport fish
- to produce ozone; ozone is used for deinfestation and sterilisation in industrial manufacturing processes.
In the steel industry, oxygen is used:
- 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
- to replace coke as the combustible.
Metal production and fabrication
In metal production and fabrication, oxygen is used:
- to replace or enrich air, increasing combustion temperatures in ferrous and non-ferrous metal production
- to create a hot flame in high-temperature welding torches used in cutting and welding
- to support oxyfuel cutting operations
- sometimes added in small quantities for shielding gases.
The Chemical industry
In the chemical industry, oxygen is used:
- to alter the structure of feedstocks through oxidation, producing nitric acid, ethylene oxide, propylene oxide, vinyl chloride monomer and other building block chemicals
- to increase capacity and the destruction efficiency of waste incinerators.
Pulp and paper industry
In the pulp and paper industry, oxygen is used:
- 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.
In the glass industry, oxygen is used:
- to enhance combustion in glass furnaces and forehearths, reducing nitrogen oxide (NOx) emissions.
In the petroleum industry, oxygen is used:
- 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 feedstocks
- to reduce sulphur emissions in refineries.
Water and waste
Oxygen is used for water and wastewater treatment.
In health services, oxygen is used:
- to resuscitate or, in combination with other gases, to anaesthetize
- as an essential part of life-support systems in emergencies or in the long-term treatment of patients with respiratory disorders.
In power generation, oxygen is used:
- to convert coal to electricity.
Oxygen, the second-largest volume industrial gas, is produced commercially by the air separation process. This process consists of separating the components contained in the air:
- nitrogen (78 %)
- oxygen (21 %)
- argon (0,9 %)
- other gases (0,1 %).
Present day plants represent the evolution of the Claude-Linde process named after the French and German scientists who contributed to their development; for air cooling they initially adopted isoenthalpic expansion, just with pressure drop, and later isoentropic expansion, with energy production.
The plant consists of two columns, one above the other, operating at different pressures and with gas flow (rising) and liquid flow (descending) in equilibrium between the gas and liquid phases. As one gets towards the top of the column there is an increasing concentration of nitrogen and towards the bottom an increasing concentration of oxygen.
Argon is obtained in a third fractionation column, in which the distillation process is repeated on an oxygen-argon mixture taken from an intermediate point of the upper column.
Present day air separation plants have reached a high degree of automation and their control is carried out via a computer; the control system handles the entire production cycle and the following phase of product distribution up to storage or utilisation.
In the Osio Sopra production plant, Italy's most state-of-the-art plant in the field of Industrial Gases and the biggest of SIAD's production units, the new air separation plant T 1000, which went live in September 1997 and replaced part of the older plants, assures a production capacity on the site of 1300 tons of oxygen per day.
The plant was designed by SIAD MACCHINE IMPIANTI.
In the Osio Sopra factory, SIAD also produces ultrapure oxygen (grade 6.0): it is obtained through a double distillation plant which uses industrial oxygen as the raw material.
Oxygen supply options and services available to SIAD customers include:
- transport in cylinders, cylinder packs or tanks
- design and installation of gas distribution systems
- supply of equipment for the correct use of the gas
- assistance and technical consultancy for the transport, distribution and application of the gas.
Oxygen can also be supplied:
- with grades 2.8 - 3.5 - 5.0 purity
- liquid grade 5.0
- in welding mixtures of various compositions
- in special and in calibration mixtures with different compositions upon request
- in synthetic air.