Oxygen Blowing Lance and its Role in Basic Oxygen Furnace Oct10

Oxygen Blowing Lance and its Role in Basic Oxygen Furnace...

Oxygen Blowing Lance and its Role in Basic Oxygen Furnace In the basic oxygen furnace (BOF) steel making a water-cooled lance is used for injecting a high velocity (super-sonic) stream of oxygen onto the liquid bath for its refining. The velocity or momentum of the oxygen jet results in the penetration of the liquid slag and metal to promote oxidation reactions over a relatively small area. The velocity of the oxygen jet and the penetration characteristics are functions of the nozzle (lance tip) design. The top-blowing lance oxygen jet of the BOF converter works as the source of feeding oxygen and energy for stirring of the liquid metal in the bath. Major in-furnace phenomena of a BOF converter that involve the top-blowing lance oxygen jet are formation of a cavity as a result of physical interaction between the oxygen jet and liquid metal, stirring of liquid metal, generation of spitting and dust, and post combustion of CO gas generated by decarburization and reaction with oxygen. For the optimization of BOF converter operation and control the above phenomena, different devices and improvements have been made and applied to the design and operation of top-blowing lance. Examples of these include the employment of Laval nozzles capable of converting pressure energy to jet kinetic energy with high efficiency in order to promote stirring of liquid metal, and the use of a multi-hole lance that enables high-speed oxygen feeding while suppressing generation of spitting and dust by dispersing of the oxygen jet. With the introduction of combined blowing in the BOF converters, the role of top-blowing lance jets as the source of energy for stirring liquid metal iron declined and flexibility in design and operation has been enhanced significantly. The main reason for blowing oxygen into the liquid...

Blowing of Oxygen in Converter Steelmaking Sep14

Blowing of Oxygen in Converter Steelmaking...

 Blowing of Oxygen in Converter Steelmaking Oxygen (O2) is blown on the hot metal in the converter during steel making for removal of impurities such as carbon (C), silicon (Si), manganese (Mn), and phosphorus (P) etc.  A water cooled lance is used to inject oxygen at very high velocities onto a liquid bath to produce steel. In the 1950s when the top blown converter process was commercialized and the size of the converter was limited to 50 tons maximum then a lance with a single hole lance tip was being used for the blowing of O2 in the converter. With the passage of time the converter size went on increasing. This has necessitated increase of number of holes in the lance tip for better distribution of O2 over a larger surface of the bath in the converter. With the increasing demands to produce higher quality steels with lower impurity levels, O2 of very high purity is required for steelmaking in the converter. The O2 needed for steelmaking is to be at least 99.5 % pure, and ideally 99.7 % to 99.8 % pure. The remaining parts are 0.005 % to 0.01 % nitrogen (N2) and the rest is argon (Ar). In top-blown converters, the O2 is jetted at supersonic velocities with convergent divergent nozzles at the tip of the water cooled lance. A forceful gas jet penetrates the slag and impinges onto the surface of the liquid bath to refine the steel. Today most of the converters operate with lance tips containing 3 to 6 nozzles. Even 8 nozzles lance tips are under use. The axes of each of the nozzles in a lance with a multi hole lance tip are inclined with respect to the lance axes and equally spaced around the tip....

Oxygen gas and its usage in Steel Plant...

Oxygen gas and its usage in Steel Plant Oxygen is an active, life sustaining component of the atmosphere. The percentage of oxygen in air is 20.94 % by volume or 23 % by weight of the air. It is the most widely occurring element on the mother earth.  Because it forms compounds with virtually all chemical elements except the noble gases, most terrestrial oxygen is bound with other elements in compounds such as silicates, oxides, and water. Oxygen is also dissolved in rivers, lakes, and oceans.  Molecular oxygen occurs almost entirely in the atmosphere. Between 1770 and 1780, Swedish pharmacist Carl Wilhelm Scheele, British clergyman Joseph Priestley and French chemist Antoine Laurent Lavoisier researched, documented and helped discover oxygen. The name oxygen was first used by Lavoisier in 1777. It was only later that its high level of chemical reactivity was discovered. Oxygen 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 (typically about 93 %) by adsorption technologies (pressure swing adsorption (PSA), or vacuum-pressure swing adsorption (VPSA or VSA). Very pure oxygen can be produced by the electrolysis of water. Gaseous oxygen is called in short as GOX while the liquid oxygen is called in short as LOX. Liquid oxygen is a cryogenic liquid. Cryogenic liquids are liquefied gases that have a normal boiling point below – 150 deg C. Liquid oxygen has a boiling point of -183 deg C. Because the temperature difference between the product and the surrounding environment is substantial, it is necessary to keep the liquid oxygen insulated from the surrounding heat. Oxygen also requires special equipment for handling and storage....

Understanding Steel Making Operations  in Basic Oxygen Furnace Mar02

Understanding Steel Making Operations in Basic Oxygen Furnace...

Understanding Steel Making Operations  in Basic Oxygen Furnace  Steel making operation in the basic oxygen furnace (BOF) is also sometimes called basic oxygen steel making (BOS). This is the most powerful and effective steel making technology in the world. Around 71 % of the crude steel is made by this process. BOF process was developed in Austria in the early 1950s at the two Austrian steelworks at Linz and Donawitz and hence the BOF process is also called LD (first letters of the two cities) steel making. There exist several variations on the BOF process. The main are top blowing, bottom blowing, and a combination of the two which is known as combined blowing. The BOF process is autogenous, or self sufficient in energy, converts liquid iron (hot metal) into steel using gaseous oxygen (O2) to oxidize the unwanted impurities in hot metal (HM). The O2 used must be of high purity, usually 99.5% minimum, otherwise the steel may absorb harmful nitrogen (N2). The primary raw materials for the BOF are generally HM (around 80 % or more) from the blast furnace and the remaining steel scrap. These are charged into the BOF vessel. O2 is blown into the BOF at supersonic velocities. It oxidizes the carbon (C) and silicon (Si) contained in the HM liberating great quantities of heat which melts the scrap. There are lesser energy contributions from the oxidation of iron(Fe), manganese (Mn), and phosphorus (P). The flux used in this process is primarily calcined lime ( with CaO content of more than 92 %). This lime is produced by the calcining of limestone with low silica (SiO2) content. The post combustion of carbon monoxide (CO) as it exits the converter also transmits heat back to the bath. The product of...