Nitrogen gas and its usage in Steel Plant...

Nitrogen gas and its usage in Steel Plant Nitrogen is a non-reactive component of the atmosphere which is not life supporting. The percentage of nitrogen in air is 78.06 % by volume or 77 % by weight of the air. The composition of air is shown in Fig 1. Fig 1 Composition of air The element nitrogen was discovered as a separable component of air, by Scottish physician Daniel Rutherford, in 1772. Nitrogen was also studied at about the same time by Carl Wilhelm Scheele, Henry Cavendish, and Joseph Priestley, who referred to it as burnt air. Nitrogen is produced in large quantities and at high purity as a gas or liquid through the liquefaction and distillation of ambient air at the cryogenic air separation plants. It is also produced on commercial scales as a lower purity gas by adsorption technologies (pressure swing adsorption, PSA), or diffusion separation processes (permeation through specially designed hollow fibers). Gaseous nitrogen is called in short as GAN while the liquid nitrogen is called in short as LIN. Liquid nitrogen is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below – 150 deg C. Liquid nitrogen has a boiling point of -195.8 deg C. Because the temperature difference between the product and the surrounding environment is substantial, it is necessary to keep the liquid nitrogen insulated from the surrounding heat. Nitrogen is often stored as a liquid, although it is used primarily as a gas. Liquid storage is less bulky and less costly than the equivalent capacity of high-pressure gaseous storage. A typical storage system consists of a cryogenic storage tank, one or more vaporizers and a pressure control system. The cryogenic tank is constructed, in principle, like a vacuum flask. There is an inner vessel...

Cryogenic process of Air Separation Jul20

Cryogenic process of Air Separation...

Cryogenic process of Air Separation   Dry air contains by volume 78.08 % of nitrogen, 20.95 % of oxygen, and 0.93 % of argon along with traces of a number of other gases. Ambient air may contain varying amount of water vapor (depending upon humidity) and other gases produced by natural processes and human activities. Air separation plants are used for the production of nitrogen or/and oxygen as gases and sometimes as liquid products. Some plants also produce argon.  All air separation plants employ either non cryogenic based technologies or cryogenic based technologies. Non cryogenic air separation plants produce gaseous nitrogen or oxygen products using near ambient temperature separation processes. These plant produce oxygen which is typically 90 % to 95.5 pure or nitrogen which is typically 95 5 to 99.5 % oxygen free. Cryogenic air separation plants are most commonly used to produce high purity products at medium to high production rates. They can produce products as gases or liquids. This technology is based on difference in boiling points of gases. All air separation processes start with compression of air. The cost of electric energy is the largest single operating cost incurred in air separation plants. It is usually in the range of one third or two thirds of the operating costs associated with producing gas and liquid products. Cryogenic plants Cryogenic plants are based on cryogenic air separation processes.  The basic process was commercialized early in the 20th century. Since then, a large number of process configuration variations have emerged, driven by the desire to produce particular gas products and product mixes as efficiently as possible at various required levels of purity and pressure. These air separation process cycles have evolved in parallel with advances in compression machinery, heat exchangers, distillation technology and gas expander technology....