Management of Greenhouse Gas Emissions in Integrated Steel Plant...

Management of Greenhouse Gas Emissions in Integrated Steel Plant Major constituents of greenhouse gases are carbon di oxide (CO2), methane (CH4), nitrous oxide (N2O), various fluorocarbons, sulphur hexafluoride, halons, and ozone in troposphere. Each of these gases has a different greenhouse warming potential (GWP) and their effects on atmosphere are not in direct proportion to their quantity of emissions. The GWP of a greenhouse gas is a measure which indicates of how much a given mass of gas contributes to the global warming. The GWPs of different greenhouse gases are given on a relative scale. This scale compares the GWP of the gas in question to the GWP of carbon di oxide gas which is considered as 1.0. Over 100 years of time horizon the GWP of methane is 21, whereas the GWP of nitrous oxide is 310 (Fig 1). Hydro fluorocarbons (HFC) which are used in some of the air conditioning systems of the steel plant have a GWP of up to 11700. Sulfur hexafluoride (SF6) used in some of the circuit breakers of the electrical transmission system of the steel plant has a GWP of up to 23900. Fig 1 Global warming potential of greenhouse gases The manufacture of iron and steel is an energy intensive activity that generates carbon dioxide, methane, and nitrous oxide emissions at various stages during the production process. Although CO2 is easily the main GHG emitted from an integrated iron and steel plant, N2O and CH4 emissions are not necessarily be small. The greenhouse gas which is the most relevant from the steel plant is CO2. The Steel Industry represents 6 % to 7 % of global anthropogenic CO2 emissions according to the Intergovernmental Panel for Climate Change (IPCC), but only 4 % to 5 % according...

Natural Gas- its Characteristics and Safety Requirements...

Natural Gas- its Characteristics and Safety Requirements Natural gas (NG)  is a fuel gas which is used in steel plants as an auxiliary fuel for injection in blast furnace, for the production of gas based direct reduced iron, and for heating in various furnaces subject to local availability and the cost. NG is an environmentally friendly non renewable fossil fuel which is found in underground deposits in its gas phase. It exists as a gas under atmospheric conditions. It is basically a hydrocarbon gas mixture consisting primarily of methane. It is a clean fuel with a high efficiency. NG is normally supplied as (i) piped natural gas (PNG),  (ii) compressed natural gas (CNG), and (iii) liquefied natural gas (LNG). Modes of handling natural gas is given in Fig 1. Fig 1 Modes of handling natural gas NG is transported normally to long distances (up to 5000 kms) through a pipeline net work. The pressure of NG in the pipeline depends on several factors which include (i) quantity of gas to be transported, (ii) diameter of the pipeline,  (iii) the distances involved, and (iv) the safety of the gas pipeline and environment. However at the consumer end the pipeline pressure is generally less than 16 atmosphere. CNG is a form of natural gas which undergoes compression (200 to 250 kg/sq cm) into containers wherefrom it is relayed to consumers who, due to geographic and other reasons are incapable of connecting into the NG pipeline. CNG is storable. Unlike NG conveyed via pipelines and immediately consumed (similarly to electricity), CNG can be used for storage and for discontinuous utilization. NG compression into containers raises risk levels. LNG is made by cooling natural gas to a temperature of minus 162 deg C. At this temperature, natural gas becomes...

Production of DRI with Coke Oven Gas as Reductant Jul05

Production of DRI with Coke Oven Gas as Reductant...

Production of DRI with Coke Oven Gas as Reductant  Direct reduced iron (DRI) is technically defined as iron ore which has been reduced to metal without melting it. A DRI production process is one in which the solid metallic iron is obtained directly from solid iron ore without subjecting the ore or the metal to fusion. Major DRI production processes are either gas based or coal based. Feed material in a DRI process is either iron ore sized to 10 to 30 mm or iron ore pellets produced in an iron ore pellet plant. In the gas based plant the reactor, where the reduction reaction takes place, is a shaft furnace.  The shaft furnace works on counter current principle where the iron bearing feed material moves downward in the furnace by gravity and gets reduced by the up flowing reducing gases. In a gas based process gaseous fuels are used. These fuels should be able to reform or crack to produce a mixture of H2 (hydrogen) and CO (carbon monoxide) gas. High methane containing natural gas is the most commonly used gas. Natural gas is reformed to enrich with H2 and CO mixture and this enriched and reformed gas mixture is preheated. Coke oven gas (COG) is a byproduct of the coke making process in byproduct coke oven battery. COG consists of a complex mixture of various gases. Its composition typically consists of 55 % H2, 6 % CO, 25 % CH4 (methane), plus small percentages of CO2 (Carbon dioxide), H2O (moisture), heavy tars, volatile hydrocarbons and sulphur impurities. It also contains some N2 (nitrogen). COG is typically used as fuel gas for various heating applications within the steel plant, and surplus COG is used to produce steam, electrical power or is flared. Use...