Natural gas and its Usage in Iron and Steel Industry...

Natural gas and its Usage in Iron and Steel Industry Natural gas (NG) is an environmentally friendly non-renewable gaseous fossil fuel which is extracted from deposits in the earth. It is a clean and green fuel with a high efficiency and plays a major role in helping many industries cut emissions and improve the overall air quality. It is normally supplied as (i) piped natural gas (PNG), (ii) compressed natural gas (CNG), and (iii) liquefied natural gas (LNG). Natural gas is a mixture of hydro-carbons consisting primarily of methane (CH4), generally in a percentage of over 85 % by volume. Other hydro-carbons in NG include varying amounts of various higher alkanes such as ethane, propane, and butane etc. It also contains water vapour (H2O) at varying degrees of saturation, or condensed water. It may also contain some small percentage of nitrogen (N2), carbon dioxide (CO2) and hydrogen sulphide (H2S) and helium (He) etc. NG burns with a clean blue luminous flame when mixed with the requisite amount of air and ignited. It is considered one of the cleanest burning fuels. On burning, it produces primarily heat, CO2, and water vapour. NG is a fuel found in deposits in its gas phase. It is colourless and odourless, non-toxic, and lighter than air. It does not contain olefins (hydrocarbons produced during the process of destructive distillation or reforming). It is a highly flammable and combustible gas. Its CAS number is 8006-14-2 and UN number is 1971. Quantities of natural gas are measured in normal cubic meters (corresponding to 0 deg C and 1 atmosphere pressure) or standard cubic feet (corresponding to 16 deg C and 14.73 pounds per square inch absolute pressure). The higher heat value of one cubic meter of natural gas varies from around 9500...

Industrial Heating Furnaces and their Types...

Industrial Heating Furnaces and their Types A furnace is equipment which is used as a reactor, or for melting of metals for casting, or to heat materials to change their shape (e.g. rolling, forging etc.) or properties (heat treatment). Industrial furnaces are mainly used for carrying out the process or for the purpose of heating. Furnaces which are used for carrying out the processes are sometimes known as reactors. Industrial furnaces which do not ‘show colour’, that is, in which the temperature is below 650 deg C are sometimes called ‘ovens’. However, the dividing line between ovens and furnaces is not very sharp. As an example, coke ovens operate at temperatures above 1400 deg C. In the ceramic industry, furnaces are called ‘kilns’. In the petrochemical and chemical process industries, furnaces are termed ‘heaters’, ‘kilns’, ‘afterburners’, ‘incinerators’, or ‘destructors’. The furnace of a boiler is known as its ‘firebox’ or ‘combustion chamber. Industrial heating furnaces are insulated enclosures designed to deliver heat to loads for many forms of heat processing. Furnaces used as reactors, and melting furnaces require very high temperatures and can involve erosive and corrosive conditions. Shaping operations need high temperatures to soften materials for processes such as forging, swaging, rolling, pressing, bending, and extruding etc. Heat treating operations need midrange temperatures to physically change crystalline structures or chemically (metallurgically) alter surface compounds, including hardening or relieving strains in metals, or modifying their ductility. These include aging, annealing, normalizing, tempering, austenitizing, carburizing, hardening, malleabilizing, nitriding, sintering, spheroidizing, and stress relieving etc. Industrial processes which use low temperatures include drying, coating, polymerizing, and chemical changes etc. Industrial heating operations encompass a wide range of temperatures, which depend partly on the material being heated and partly on the purpose of the heating process and...

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...

Energy Audit in an Integrated Iron and Steel Plant...

Energy Audit in an Integrated Iron and Steel Plant Energy audit is a key requirement for an integrated iron and steel plant which helps it to identify and realize energy efficiency improvements in a systematic way. It assists the steel plant management in understanding how it uses energy and helps to identify the areas where waste occurs and where opportunities for improvement exist. Energy audit is the inspection, examination, analysis and evaluation of the physical and financial processes of the steel plant relating to the use of the energy. The aim of the energy audit is to systematically identify the potential for saving energy and make recommendations for improvement. Energy audit is the key to a systematic approach for decision making in the area of energy management.It attempts to balance the total energy inputs with its use, and serves to identify all the energy streams in the steel plant. It quantifies energy usage according to its discrete functions. It is an effective tool in defining and pursuing comprehensive management of the energy usage in various processes of the steel plant. Energy audit helps to understand more about the ways energies and fuels are used in various processes of the steel plant. It helps in identifying the areas where waste of energy is occurring and where scope for improvement in energy consumption exists. It gives a positive orientation to the energy cost reduction and helps to keep focus on variations which occur in the availability and reliability of supply of energies and their costs, decide on appropriate energy mix, identify energy conservation technologies, retrofit for energy conservation equipment etc. It is the translation of conservation ideas into realities, by identifying technically feasible solutions with economic and other organizational considerations within a specified time frame. Energy...