Waste water and waste water treatment in the Steel Plant Jul20

Waste water and waste water treatment in the Steel Plant...

Waste water and waste water treatment in the Steel Plant Steel plants use a large amount of water for a variety of usage which includes cooling, dust suppression, cleaning, temperature control (heat treatment), transport of waste materials (ash, sludge, and scale etc.), and other usages. Water is an essential part of some processes such as moisture content of coking coal, pelletizing of sinter mix, making of green pellets during the production of iron ore pellets, production of steam and hence power, and granulation of blast furnace slag etc. Use of large amount of water also generate huge quantity of waste water which may contain suspended solids and many dissolved substances and chemicals. The quality of waste water depends on the process where the water is used and for the purpose for which it is used. The major environmental effects of the untreated waste waters of the steel plant if discharged into the receiving water bodies are namely (i) toxicity to aquatic life, (ii) reduction of dissolved oxygen, (iii) silting due to suspended solids, (iv) taste and odour problems, (v) temperature rise affecting the dissolved oxygen, (vi) effect on the aquatic life, and (vii) formation of oil slicks due to the floating oil etc. The large volumes of process water that come into direct contact with the raw materials, products, and off gases is required to be treated for reuse of water, for recycle of the water, or for the removal of pollutants to the levels fixed by the regulatory authorities prior to its discharge. The quality of waste water can be controlled by adopting improved technologies developed for different processes these days. Technologies are also available now to treat the waste water fit for either recycling in the same process or in other processes....

Water used in Steel Plant and its Types...

Water used in Steel Plant and its Types Water is used in every shop of a steel plant and for practically all the functions of water. A steel plant cannot function without water. Because of this steel plants are normally built near to ample sources of fresh water to ensure the availability and quality of water needed by the steel plant. However these days, greater attention is given to the management of available water resources in the steel plant environment, particularly in terms of water quality, quantity, and how it is used. A steel plant uses large quantity of water for steam generation, cooling, waste transfer, and dust control etc. The processes of the plant cannot take place without the availability of water. Enormous quantity of water is needed at every stage of production. Less than 10 % of this water is actually consumed and balance water is usually is returned to the system. Several factors make water a versatile material. It is normally easy to handle, readily available, and inexpensive. It can carry large amounts of heat per unit volume (high specific heat). It neither expands nor compresses significantly within ambient temperature ranges. It does not decompose. It can dissolve, entrain, suspend, and subsequently transport other materials. In spite of the tremendous importance of water in the steel plants (Fig 1), the way water is used is not standardized as are the steel production processes and there is no ‘one size fits all’ strategy or technology to use water in each particular context. There are a number of aspects related to water and water related technologies which are important for a steel plant. These are given below. Water is a medium for heat transfer and thus is related to energy efficiency Importance of...

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...

Universal Beams and its Rolling Jul13

Universal Beams and its Rolling...

Universal Beams and its Rolling Universal beams are also known as parallel flange beams or wide flange beams. The cross section of a universal beam is either I or H shape. H shape beams are also referred as universal columns. The horizontal portion of the cross section of a universal beam is known as flanges, while the vertical element is termed as web. H beam has wider flanges than I beam. Universal beams are usually rolled from structural steels and are used in construction and civil engineering. The universal beam has the most efficient cross sectional profile since most of its material is located away from the neutral axis providing a high second moment of area, which in turn increases the stiffness, hence resistance to bending and deflection. H beams have equal or near-equal width and depth and are more suited to being oriented vertically to carry axial load such as columns in multi-storey construction, while I beams are significantly deeper than they are wide are more suited to carrying bending load such as beam elements in floors. When a beam bends the top of the beam is in compression and the bottom is in tension.  These forces are greatest at the very top and very bottom. Since a universal beam has higher amount of material at the top and bottom sides and smaller material in the web, it provides a structural section which is stiff with use of least material. Though I-beams are excellent for unidirectional bending in a plane parallel to the web, they do not perform as well in bidirectional bending. These beams also show little resistance to twisting and undergo sectional warping under torsional loading. For torsion dominated problems, box sections and other types of stiff sections are used in preference...

Argon gas and its usage in Steel Plant...

Argon gas and its usage in Steel Plant Argon (Ar) gas is present in very small percentage in the atmosphere. Argon is very inert and hence it is referred to as one of the noble gases. It is not known to form true chemical compounds. It makes a good atmosphere for working with air sensitive materials since it is heavier than air and less reactive than nitrogen gas. Argon gas is the most abundant of the noble gases. It is a non-reactive component of the atmosphere. It constitutes 0.934 % by volume and 1.288 % by mass of the earth’s atmosphere. Argon was suspected to be present in air by Henry Cavendish in 1785 but was not isolated until 1894 by Lord Rayleigh and Sir Willam Ramsay at University college London in an experiment in which they removed all of the oxygen, carbon dioxide, water and nitrogen from a sample of clean air. Argon gas is produced by the fractional distillation of liquid air at the cryogenic air separation plants. It is produced, most commonly, in conjunction with the manufacture of high purity oxygen using cryogenic distillation of air.  Since the boiling point of argon is very close to that of oxygen (a difference of only 2.9 deg C) separating pure argon from oxygen (while also achieving high recovery of both products) requires many stages of distillation. For many decades, the most common argon recovery and purification process used several steps namely (i) taking of a side-draw stream from the primary air separation distillation system at a point in the low-pressure column where the concentration of argon is highest, (ii) processing the feed in a crude argon column which  returns the nitrogen to the low pressure column and produces a crude argon product, (iii) warming the crude argon and reacting...