Energy Management in Small and Medium sized Re-rolling mills...

Energy Management in Small and Medium sized Re-rolling mills Energy consumption in small and medium sized re-rolling mills takes place in two forms namely (i) electrical energy, and (ii) fuel or heat energy. Electrical energy is used directly in main rolling process for shaping of hot billets into rolled product (rolling mill, and shears etc.), in reheating furnace (coal pulverizer, blower, and pusher etc.) and also in auxiliary (roll turning machines, pumps, man coolers, overhead crane etc.), and shop lighting. Fuel energy is used in the reheating furnace for raising the temperature of the feed material to desired temperatures (generally 1150 deg C–1250 deg C). The division of the energy in these two forms normally varies from mill to mill based on the practices employed as well facilities installed in the re-rolling mills in SME (small and medium enterprise) sector. However, the share of electrical energy in small and medium sized mill generally varies in the range 20 % to 30 %. Consumption of fuel energy takes the major share of the energy consumption and usually constitutes 70 % to 80 %. From a theoretical perspective, the energy in hot rolling is primarily determined by the requirements of reheating of feed material. The theoretical energy for deformation is only 0.02 GJ/ton (around 5000 kcal/ton), compared to 0.83 GJ/ton (around 200,000 kcal /ton) for heating billets when charged cold in the reheating furnace. Though it is not technically feasible to achieve theoretical energy consumption figures, but the energy efficiency of the rolling mill is depends upon how close it is to the theoretical consumption. Management of electrical energy consumption Out of the total electrical energy consumed by a re-rolling mill, the share of the process of rolling is in the range of around 60 %...

Important Issues related to Re-rolling mills in SME Sector...

Important Issues related to Re-rolling mills in SME Sector The steel sector in India consists of four branches namely (i) multi-million tons integrated steel plants, (ii) mini integrated steel plants, (iii) individual units of steel melting producing pencil ingots, and (iv) re-rolling mills which are rolling steel from billets, pencil ingots and scrap steel. Most of the units under last two categories are in small and medium enterprise (SME) sector. All the four branches which constitute the steel sector play a very important role in the steel economy of the country. Re-rolling mills has a considerable contribution to the steel production of the country.  There are around 1800 re-rolling mills in SME sector in India. The rolling capacities of these mills are mostly in the range of 8,000 tons per year to 80,000 tons per year. On a very conservative estimate, these mills contribute more than 20 % of the total production of finished steel in the country. Hence, these mills play a very important role in supporting the steel economy of the country. The conditions of the most of the re-rolling mills can be termed as not healthy. They operate with very old technologies and operate at low level of productivities and high level of energy consumptions. There are many problems and challenges associated with these mills. Several agencies have carried out detailed studies of the steel and re-rolling units of SME sector. Some of these studies have identified certain barriers associated with these mills (Fig 1) which include (i) high energy consumption due to the use of obsolete technologies, (ii) lack of awareness and knowledge on several fronts, (iii) lack of proper operational procedures, (iv) a negative mind-set among owners of the mills, and (v) lack of finance to effect necessary changes...

Management of Re-rolling mills in SME sector...

Management of Re-rolling mills in SME sector Re-rolling mills in SME sector play a very important role towards the steel economy of the country. There are around 1800 re-rolling mills in small and medium enterprise (SME) sector in India. The rolling capacities of these mills are mostly in the range of 8,000 tons per year to 80,000 tons per year. These mills are crucial to the national economy since they are not only making available a large amount of finished steel in the market but many of these mills are also converting a substantial amount of steel scrap into finished steel thus serving the overall cause of steel recycling. Since the conversion of steel scrap is taking place without its melting in these re-rolling mills, it is helping towards the cause of the conservation of raw materials and energy as well as saving the generation of green-house gases. The technology adoption level of these mills is rather low and many of these mills operate with technologies which are 50 years to 60 years old. Most of these re-rolling mills do not have practices to keep systematic data in different areas of their functioning. These mills operate at low level of productivities and high level of energy consumptions. They have some special problems and challenges. Re-rolling mills in SME sector practically do not have even simple control systems. They work with a low degree of standardization. The work force is having high experience in limited area. There is increased focus on the experience of the people and there is practically no effort to enhance the knowledge of the work force. The approach to all the issues is informal leading to decisions which does not often bring improvements in the working of the mills. Re-rolling mills...