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....

Environmental Performance of Iron and Steel Plant...

Environmental Performance of Iron and Steel Plant Environmental concerns associated with various processes of the iron and steel plant relate to mainly (i) atmospheric emissions, (ii) waste water and liquid effluents discharges, and (iii) solid wastes generation and disposal (Fig 1). There are regulatory requirements which are to be complied. Environmental performance of the plant greatly impacts the natural environment around the plant. Environmental management practices are followed by the plant management to address to the environmental concerns and to take reasonable and practical measures to preserve and enhance the quality of the environment which is affected by the plant. Environmental management practices normally ensure that the plant achieves environmental performance results which are superior to the environmental standards set by the regulatory authorities. Fig 1 Environmental concerns of a steel plant The major activities and the main processes in an integrated iron and steel plant having blast furnace (BF) – basic oxygen furnace (BOF) process route, which are of relevance to the environmental performance and the associated environmental releases are described below. Raw materials handling and storage The main environmental issue relating to raw materials handling and storage is the fugitive emission of particulate matter arising from material transfers, dumper and other vehicular traffic, and wind erosion of the piles of the raw material storage. A secondary concern is the suspended solids and, in some cases, oil, contained in the runoff water from the storage areas. Fugitive emissions of particulate matter are normally controlled by spraying stockpiles with water or crusting agents and ensuring that roads and wheels of dumpers and other vehicles are kept clean. The water runoff is generally directed to a waste water treatment plant. Coke making Coke making represents perhaps the greatest environmental concern for a steel plant. Although...

Productivity and Product Quality in Continuous Casting Machine Jun25

Productivity and Product Quality in Continuous Casting Machine...

Productivity and Product Quality in Continuous Casting Machine Continuous casting is the process by which liquid steel is solidified into a semifinished steel product (billet, bloom, or slab etc.) for subsequent rolling in the hot rolling mills. Continuous casting of liquid steel was introduced for commercial application in 1950s. In the relatively short time span since the introduction of continuous casting for the commercial application, the process has evolved with a wide variety of new process developments directed towards achieving improved productivity and superior product quality. These developments include new design concepts of continuous casting machines, metallurgical practices, and the application of process control and automation by computer systems. The main driving force behind these developments has been the recognition that substantial improvement in the yield and energy savings are possible which have a dramatic effect on operating cost. Through these developments, it has been possible to achieve major quality improvements of the continuous cast product.  Present day continuous casting machines produce cast steel products having quality which is fully equivalent to and exceeds that of products produced from ingot steel. Modern continuous casting machines efficiently produce essentially all grades of steels, including the highest qualities for critical applications. Productivity improvement The two methods to improve the productivity of the continuous casting process include improving the continuous casting machine throughput (tons/hour) and net-working ratio. The through put of the continuous casting machine is improved by increasing the casting speed as well as by increasing the cross sectional area, while the net- working ratio is improved by decreasing the casting machine down time. The casting speed of the continuous casting machine is limited by several different phenomena as given below. A high casting speed results in a significant increase in the flow velocity of the...

Compressed Air System in a Steel Plant...

Compressed Air System in a Steel Plant Compressed air is the air which is kept under a pressure having a value greater than the atmospheric pressure (1.03 kg/sq cm). It is a medium that carries potential energy. Compressed air is a widely used utility in a steel plant. It is an important source of instrument air. Other than instrumentation air which is completely dry and free from contaminants, there are the following three main uses of compressed air in a steel plant. Blast air for blast furnace For the production of oxygen, nitrogen and argon in an air separation plant A utility gas with many uses. Major among it is the operation of pneumatic devices Normally for blast furnace the cold blast air is supplied either by a turbo-blower or an electric blower. In the air separation plant, there are dedicated compressors producing compressed air of the specification needed by the air separation plant for the production of oxygen, nitrogen and argon gases. In case of compressed air being used as a utility gas, steel plants usually have either a centralized compressed air system or/and local compressed air systems. Compressed air is an expensive utility when evaluated on a per unit energy delivered basis. The advantage with the use of compressed air is that it can be easily stored in air receivers and readily available for brief peak demand periods. There are inefficiencies in converting electricity into compressed air as well as line losses in the compressed air distribution. Although the total energy consumption of such systems is normally small, compressed air systems are the most expensive energy in the steel plant due to its very low efficiency. Typical energy efficiency of a compressed air system is around 12 % to 15 %.  Various measures can help...

Energy Conservation in a Steel Plant...

Energy Conservation in a Steel Plant Production of iron and steel is an energy intensive manufacturing process and needs natural resources (including the energy resource) in large amounts. Energy cost is one of the major costs in the operation of the steel plant. The energy efficiency and hence the energy consumption of the steel plant varies depending on production route, type of iron ore and coal used, the steel product mix, operation control technologies employed, and material efficiency of the plant. Conservation of energy is one of the most effective ways to improve the energy efficiency, to reduce the energy consumption, and to lower the costs with an added benefit of reducing the impact of the steel plant on the environment. In recent years, the need for a more rational and efficient use of energy has emerged as a strategic and urgent issue. The rational use of the energy resource is being regarded as a twofold issue, a first aspect being related to the achieved consciousness of the limited availability of energy, regarded as a source, and the second being represented by a mature appreciation of the costs incurred to procure energy. The cost of energy is not only the important motivation for the steel plant management to make efforts towards energy conservation and to increase the energy efficiency of the processes but the threat of energy shortages is leading the management to take steps for the conservation of the energy. Energy conservation also helps the steel plant towards its societal goal towards reduction of the generation of greenhouse gases. The composition and local conditions of each steel plant is different, and based on each unique situation the most favourable selection of energy conservation opportunities are required to be made to address to the...