Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Implementation of Green Manufacturing in reducing Carbon Contents in Steel Industry to improve Air Quality and Business Results Shahzad Ahmad1, Alia Irfan2 1Associate Professor, Department of Mechanical Engg., A.F.S.E.T, Faridabad, Haryana, India ([email protected]) 2Assistant Professor, Department of Mechanical Engg., A.F.S.E.T, Faridabad, Haryana, India ([email protected]) Abstract In recent decade, there has been increased pressure on manufacturing companies to think beyond the economic benefits of their process and products and consider the environmental and social affects. Toxic wastes and acid precipitation created by steel industry are causing crisis for thousands of communities around the world. Even more ominous, global crises such as ozone depletion, greenhouse warming, deforestation and the loss of biodiversity are in one way or another rooted in corporate products and production systems. Since the country’s growth is necessary, its environmental concerns can be moderate in the manufacturing sector by using energy and resources efficiently, and minimize generation of waste. It is estimated that even if every factory, power plant, car and aeroplane is shut down, the average global temperature would still increase by 0.6˚C in this century. ‘Green Manufacturing’ or sustainable industrial activity is now the need of the hour and no more an empty slogan. It is pointed out that adequate environment protection in a “green” steel plant does not merely mean a tolerate disposal of pollutants emitted from its operation units, but rather the effective implementation of a strategy whereby the formation of any polluting agents in any part of this plant is include proper choice and control of raw materials, and an untiring endeavour effort to optimize the complete manufacturing process of the whole steel plant. Therefore, there is a need for an integrated approach like Green Manufacturing technology towards energy and environment management of the industry so that better energy efficiency and environmental friendliness can be achieved. Keyword: Green manufacturing, CO2 emission, recycling, Sustainable development & Steel industries. -------------------------------------------------------***-------------------------------------------------------------- 1. INDRODUCTION A recent global survey by BCG reveals that as many as 92% of the companies surveyed are engaged in green initiatives. Manufacturing companies that adopt green practices benefit not only through long term cost savings, but equally importantly, from brand enhancement with customers, better regulatory traction, greater ability to attract talent and higher investor interest. However, these benefits require a long term commitment and making trade-offs against short term objectives, as the economics of green manufacturing is still evolving and not well understood as yet. The motivation for adopting green has varied across sectors. Some take it up owing to regulatory compulsions (e.g. power), while others see it as an opportunity to build a stronger brand with consumers (e.g. retail). Steel manufacturers have adopted green initiatives to stabilize rising energy costs, while automobile companies have seen it as an opportunity to launch electric and hybrid cars to meet increasingly stringent emission regulations. The impact of green initiatives also varies by the industry sector. For example, green initiatives in the power sector have the maximum impact on reducing CO2 emissions followed by transportation and then the industrial sector. Once we have achieved the focus to think green in all aspects of our industry, we are open to the possibilities that were only waiting for us to seize them. This focus, along with the pragmatic application of existing technology, will guarantee that the steel industry is recognized as a sustainable leader by other industries and the public. If green manufacturing can be put into practice successfully, the contradiction between environmental pollution and sustainable development will be effectively solved. So it is feasible and necessary for steel industry in India to adopt the green manufacturing mode. 2. WHAT ‘GREEN’ MEANS AND WHY IT IS IMPORTANT? The term “green” manufacturing can be looked at in two ways: the manufacturing of “green” products, particularly those used in renewable energy system and clean technology equipment of all kinds, and the “greening” of manufacturingreducing pollution and waste by minimizing natural resource use, recycling and reusing what was considered waste, and reducing emissions. Green manufacturing addresses a number of manufacturing matters, including 4R’s (Reduce, Reuse, Recycle and Remanufacturing), conservation, waste management, water supply, environmental protection, regulatory compliance, pollution control, and a variety of related issue. [5] A number of companies have started adopting green initiatives as an integral part of their operations. These initiatives are driven by five factors: Rising energy and input costs. Growing consumer pull for Green products. Increasing regulatory pressures as policy makers introduce new and stricter environmental and waste management laws. Technological advances which open up new attractive business opportunities. The need to enhance competitive differentiation, particularly for first movers or those who are able to break the compromise between short-term higher costs and numerous benefits (example: brand premium, new customer segments). Green has moved from being perceived as a ‘necessary evil’ to being seen as ‘good business’. Companies that undertake green initiatives stand to be advantaged on brand enhancement, traction and regulatory compliance, greater ability to attract and retain talent, enhanced customer retention and potential cost savings. However, these benefits require a long term commitment and making tradeoffs against short term objectives, as the economics of Green manufacturing are not well understood yet. 3. STEEL-MAKING ROUTE PROCESS Currently the dominating processes in the global steel production are the integrated steelworks (primary route) and the minimills (secondary route). Integrated steelworks are plants where pig iron is made by reducing iron ore in blast furnaces. The pig iron is processed in oxyplants to get the crude steel, which is later cast, rolled and finished. In mini-mills, scrap and ores are melted and converted into crude steel directly in electric arc furnaces. Other production routes do not have a significant weight in global production because they are obsolete, or because they are so new that their share in production is still very small. The first happens to the open-hearth furnace, currently used only in the former Soviet Union, China and India. Direct reduction is used mainly in zones with lack of scrap located in developing countries, and most of smelting reduction projects are not considered economically viable. [6] 3.1 Integrated steelworks In integrated steelworks the blast furnace is the main operational unit where the primary reduction of oxide ores is transformed into liquid iron, so called pig iron. Modern high-performance blast furnaces require physical and metallurgical preparation. There are two types of iron ore preparation plants: sinter and pellet plants. Pellets are nearly always made of one well-defined iron ore or concentrate at the mine and are transformed in this form. Sinter is generally produced at the iron works from pre-designed mixtures of fine ores, residues and additives. The main reducing agents in a blast furnace are coke and powdered coal forming carbon monoxide and hydrogen, which reduce the iron oxides. Coke and coal also partly act as fuels. Coke is produced from coal by means of dry distillation in a coke oven and has better physical and chemical characteristics than coal. In many cases, additional reducing agents or fuels are supplied by injection of oil natural gas and, in a few cases, plastics. A hot blast provides the necessary oxygen to form the carbon monoxide, which is the basic reducing agent for the iron oxides. The individual production units are connected both in terms of products and residues flows (mill scale, filter dusts, sludge from scrubbing BF gas or BOF gas etc.), water (common treatment of various wastewater streams, cascade usage of cooling water, etc.) and energy (COG10, BF gas, BOF gas, steam from BF top pressure turbines or basic oxygen furnaces, etc.). These interdependencies have been created to minimize emissions as well as to optimize productivity and reduce costs. [6] Energy interdependency is the most complex of these interdependencies. The dominant energy inputs are coal and, if bought from an external supply, coke. Also electricity, natural gas, oil and (in a few cases) plastics represent the energy inputs. Coke oven gas, blast furnace gas and basic oxygen furnace gas are used for many purposes (heating coke oven batteries, provision of hot blast, ignition of the sinter feed, heating of furnaces for hot rolling etc.). Steam from top pressure turbines of the blast furnaces or from basic oxygen furnaces is also used for various processes. COG and BF gas are recovered and used at all integrated steelworks. However, this is not the case for BOF gas or for steam recovery using BF top pressure turbines. Steam recovery depends on top pressure of the blast furnace, on the operation condition of the BOF and on the usability of BOF gas. 3.2 Mini-mills The direct smelting of iron-containing materials, such as scrap, is usually performed in electric arc furnaces, known as mini-mills, which play an important and increasing role in modern steelworks concepts. The major feedstock for the EAF is ferrous scrap, which may comprise of scrap from inside the steelworks, from steel product manufacturers (e.g. vehicle builders) and capital or post-consumer scrap (e.g. end of life products). Direct reduced iron (DRI) is also increasingly being used as a feedstock due both to its low gangue content and variable scrap prices. The main operations performed in an electric arc furnace plant are raw material handling and storage, furnace charging, scrap melting, steel and slag tapping and continuous casting. 3.3 Alternative techniques: smelting reduction and direct reduction Blast furnaces require coke, and coke plants are expensive and have many environmental problems associated with their operation. Thus, it would be beneficial from an economic and environmental point of view to produce iron ore without the use of coke. Nowadays, nearly all blast furnaces can reduce their coke consumption significantly by means of reductant injection at tuyeres (blast pipes). However, coke can never be fully replaced in a blast furnace because of its burden supporting function. The minimum blast furnace coke rate is approximately 200 kg/t pig iron. There is an increasing production of steel from scrap in electric arc furnaces (EAF). Production of steel from scrap consumes considerably less energy compared to the production of steel from iron ores. The problems with the quality of scrap-based steel introduce restraints and the use of direct reduced iron (DRI) as feedstock enlarges the possibilities of the EAF steelmaking route. Summarizing, the following aspects put pressure on the blast furnace production route of steel: • Environmental aspects of sinter plants, • Environmental and economical aspects of the coke oven plant, • Relative inflexibility and scale of the pig iron production, • Increasing competition by the scrap based and DRI-EAF steel-making route. On the other hand, the advantages of the BF route as regards recycling capability and economical investment should also be recognized. This has triggered the improved environmental and economical operation of the blast furnace route and the development of alternative routes for iron making. [6] 4. ENERGY EFFICIENCY IMPROVEMENT MEASURESFOR THE STEEL INDUSTRY The Iron and Steel industry is an energy intensive industry. However, industrywide technology advances, such as new process adoption and widespread adoption of advanced process controls, have reduced energy intensity by 30 percent since 1990. This section describes the energy efficiency measures that may be feasible for GHG control in the Iron and Steel industry. All measures reduce fuel consumption and, therefore, produce direct and indirect reductions in fuelassociated GHG emissions. [9] a. Sinter Plant Heat Recovery Heat recovered from the sinter plant can be used to preheat the combustion air for the burners and to produce high-pressure steam, which can then be used in steam turbines to generate power. Various systems exist for new plants (e.g., Lurgi emission optimized sintering process), and existing plants can be retrofitted. Based on a retrofitted facility in The Netherlands, fuel savings were estimated to be 0.47 MMBtu/ton (0.55 GJ/tonne) of sinter, and increased electricity generation was estimated to be 1.4 kilowatt hour per ton (kWh/ton) (0.0056 GJ/tonne) of sinter. The payback time was estimated as 2.8 years. Emissions of nitrogen oxide (NOx), sulfur oxide (SOx), and PM are expected to be reduced. b. Coke Dry Quenching Dry quenching of the coke, in place of wet quenching, can be used to recover sensible heat that would otherwise be lost from the coke while reducing dust. The steam recovery rate with this equipment is about 0.5 MMBtu/ton (0.55 GJ/tonne) coke. The coke dry quenching (CDQ) process offers distinct advantages of sensible heat recovery, conservation of water and zero air and water pollution. In addition, Nippon Steel's performance record shows that the use of coke manufactured by dry quenching reduces the amount of coke consumption in the blast furnace by 0.24 MMBtu/ton (0.28 GJ/tonne)4 molten iron. c. Recovery of Blast Furnace Gas Approximately 1.5 percent of the gas used in the blast furnace may be lost during charging, which could be recovered. A recovery system has been installed on a furnace in The Netherlands at a cost of $0.43/ton ($0.47/tonne) of hot metal. Energy savings have been estimated to be approximately 17 kWh/ton (0.066 GJ/tonne) of hot metal. The payback time is estimated as 2.3 years. d. Oil Injection Heavy fuel oil or waste oil can also be injected instead of coke. The coke replacement rate is 1 ton of oil (0.9 tonnes) to replace 1.2 tons (1.1 tonnes) of coke. Like natural gas, oil contains hydrogen, leading to decreased CO2 emissions. If oil injection is used along with oxygen burner technology, the amount of oil injected can be increased by 100 percent as compared to regular burners. This increase would correspond to a one-to-one weight ratio between the oil injected and the hot metal produced. e. Pulverized Coal Injection Almost all Integrated Iron and Steel plants have implemented pulverized coal injection at varying injection rates. Pulverized coal and natural gas injection replaces the use of coke, thereby reducing coke production and saving the large amount of energy consumed in coke making, reducing emissions from coke ovens, and reducing maintenance costs. The energy savings in the blast furnace due to coal injection have been calculated at 3.23 MMBtu/ton (3.76 GJ/tonne) coal injected. Fuel savings were estimated to be 0.66 MMBtu/ton (0.77 GJ/tonne) of hot metal, with capital costs of $9.92/ton ($10.94/tonne) of hot metal. f. Recuperator Hot-Blast Stove The hot-blast stove flue gases can be used to preheat the combustion air of the blast furnace. Various systems have been implemented, with fuel savings ranging from 20 to 21 kWh/ton (0.080 to 0.085 GJ/tonne) of hot metal at a cost of approximately $19 to 21/MMBtu ($18 to $20/GJ) saved (equivalent to approximately $2.0/ton [$2.2/tonne] of hot metal). Preheating can lead to an energy saving of approximately 0.3 MMBtu/ton pig iron (0.35 GJ/tonne). An efficient hot-blast stove can run without the need for natural gas. [7] 5. ENVIRONMENTAL RELEVANCE In integrated steelworks, sinter plants produce the highest levels of emissions for most atmospheric pollutants, followed by coke-oven plants. Blast furnaces, basic oxygen steel making, coke ovens as well as electric arc furnaces have considerable relative percentages of dust emission. g. Flameless Burner This technology carries out combustion under diluted oxygen conditions using internal flue gas recirculation and the flame becomes invisible. Flameless oxyfuel gives high thermal efficiency, higher levels of heat flux, and reduced fuel consumption compared to conventional oxy-fuel. These benefits are combined with low NOx emissions and better thermal uniformity. Since 2003, more than 30 furnaces within the U.S. steel industry have been equipped with flameless oxyfuel combustion. ArcelorMittal recently received the Association for Iron & Steel Technology (AIST) 2009 Energy Achievement Award for its work to implement a flameless oxy-fuel operation on its rotary-hearth steel-reheat furnace. ArcelorMittal realized a 60 percent reduction in the furnace’s total fuel consumption compared to the original airfuel operation. The technology also reduced the furnace’s annual NOx emissions output by 92 percent and annual CO2 emissions by up to 60 percent below the prior air-fuel operating levels. CO2 direct emissions basically depend on the consumption of fossil fuels, the energy mix, and the production level. The reference simulation gives in 2030 a decrease of 29%, from 1990, in the world total amount of energy used by the sector, produced by the shift to cleaner (and cheaper) technologies and fuels. Coal and coke dominate the energy input in 1990. By 2030, coal consumption drops 58% and coke 54%. Energy efficiency improvements are reached at the expense of solid fuels. Technological improvements in the secondary routes avoid a higher increase in the consumption of electricity. In BOF process, secondary emissions takes place during charging, oxygen lancing and tapping. [4] h. Scrap Preheating Scrap preheating is used extensively in Japan, and the use of hot furnace gases for scrap preheating is now being applied in the U.S. Scrap preheating can save 4 to 50 kWh/ton (0.016 to 0.20 GJ/tonne) and reduce tap-to-tap times by 8 to 10 minutes. Preheating scrap reduces the power consumption of the EAF by using the waste heat of the EAF as the energy source for the preheat operation. Metallurgical wastewater is generated during off gas cleaning. For fugitive dust control, a total housing or enclosure system (dog house) installed for converter vessel capture the fugitive dust which is cleaned in a bag filter or ESP. The off-gas from BOF (also called LD gas) is rich in energy which can be used for reheating and power generation purpose. Nearly 2-4% of the energy required in the steel plant is supplied by LD gas. Metallurgical wastewater generated during off cleaning from BOF and BF which are mixed together and treated. Metals are recovered in sludge and water is recycled in the process. Most of the Indian plant have adopted combination of off-gas collection and combination system. Yet the fugitive emissions are still high because of nonfunctional emission control system. High amount of CO2 in can combusted in the furnace freeboard or in the 4rth hole evacuation system conveying the offgases to the bag house for cleaning. Steel scrap has become the steel industry's single largest source of raw material because it is economically advantageous to recycle old steel into new steel. In light of this, steelmaking furnaces have been designed to consume steel scrap. [4] a. Environment protection (Air pollution and water pollution) Recycling reduces the need for extracting (mining, quarrying and logging), refining and processing raw materials all of which create substantial air and water pollution. As recycling saves energy it also reduces greenhouse gas emissions, which helps to tackle climate change. Currently, UK recycling is estimated to save more than 18 million tons of carbon dioxide a yearthe equivalent to taking 5 million cars off the road (steel recycling institute). [1] b. Reduced landfill When we recycle, steel scrap materials are reprocessed into new products, and as a result of this, the amounts of scraps sent to landfill sites are substantially reduced. c. Energy saving Using steel scrap in the manufacturing of new steel uses considerably lesser energy than that required for producing new steel from virgin raw materials (iron ore, coal, limestone). Not only that, there is also extra energy savings because more energy is required to extract, refine, transport and process raw materials ready for industry use compared with providing steel scrap which are ready materials to be charged into the Electric Arc Furnace for easy and faster steel production d. Conservation of Resources Steel scrap reduces the consumption of valuable minerals like iron ore, coal, limestone and water. For every metric ton of recycled steel scrap, 1.5tons of iron ore, 0.5ton of coal, 0.054ton (120 pound) of limestone and 40%of water normally used in the production from virgin material is conserved. 6. CONCLUSION Efforts to achieve deep GHG emission reductions will have significant consequences for materials use. About 36% of all CO2 emissions can be attributed to industry, mainly to materials production processes. In addition, certain process improvements are dependent on a better understanding of materials transformation processes. About 18-26% improvement can be achieved based on existing technologies, but this is not sufficient to compensate for the projected growth in demand. Further improvements can be achieved only through better materials and new emerging production processes. Materials recycling reduces the energy needs and direct CO2 emissions substantially, by a factor of 2 to 4. Total scrap recovery in steel production increased from about 325Mt to 450Mt from 1970 to 2003. This increase is the net result of a decreasing amount of home scrap (an indication of fabrication yield improvements) and an increasing amount of so-called obsolete scrap (i.e., postconsumer waste, in contrast to processing waste or pre-consumer waste). Even though the recycling rate is high, an expanding economy has meant that the total crude steel production is roughly twice the amount of scrap collected and used. Net additions to the stock of materials in the economy constitute a major materials sink. Materials losses from the life cycle of steel are small, so increased recycling is an improvement option of secondary importance. The CO2 breakthrough program of the International Iron and Steel Institute aims for the development of CO2-free steel production processes. The European activities under this heading are named ULCOS (UltraLow CO2 Steel). In the second stage of this project, industry has selected three process routes for further development: (1) blast furnaces in combination with CO2 capture and storage; (2) natural-gasbased reduction processes (with CO2 capture and storage); and (3) electrolysis production processes, similar to aluminum smelting. It is pointed out that adequate environment protection in a “green” steel plant does not just mean a accept disposal of pollutants emitted from its operation units, but rather the effective implementation of a strategy whereby the formation of any polluting agents in any part of this plant is include proper choice and control of raw materials, and a constant endeavor effort to optimize the complete manufacturing process of the whole steel plant. Through the findings of this work, recycling of steel s crap is suggested as an alternative to boost the local content of steel production, reduce energy consumption, carbon dioxide emis -sion (as the world production and manufacturing system is going green). The implementation of green manufacturing focused on investigating the energy saving and CO2 emission from producing steel and effective utilization of recycling of steel scrap as a way of sustainable development in steel industry. REFERENCES 1. Mr. Shahzad Ahmad, “Sustainable Development In Steel Industries After the Implementation of Green Manufacturing”, Volume 2, Issue 4; 871875. 2. Prof. Shailee G. Acharya, “A Review on Evaluating Green Manufacturing for Sustainable Development in Foundry Industries”, Volume 4, Issue 1, January 2014; 232-237. 3. Mr. Md. Salman Alvi1, Mr. Shahzad Ahmed, “Approaching Green Manufacturing In Iron and Steel Industry”, Volume 2, No. 3, July 2013, 108-112. 4. Mr. Sanjeev K Kanchan, Special article on “Pollution and Control in Steel Industries”, CSE, New Delhi. 5. Mr. Minhaj Ahemad .A. Rehman, Mr. R. R Shrivastava, “Validating Green Manufacturing (GM) Framework for Sustainable Development in an Indian Steel Industry”, Universal Journal of Mechanical Engineering 1(2), 2013; 4961. 6. Mr. Ignacio Hidalgo, Mr. Laszlo Szabo, “Energy consumption and CO2 emissions from the World Iron and Steel Industry”, March 2003. 7. “Emerging Energy-efficiency and Carbon Dioxide Emissions Reduction Technologies for the Iron and Steel Industry”, Mr. Ali Hasanbeigi, Mr. Lynn Price, China Energy Group, Energy Analysis and Environmental Impacts Department, Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Ms. Marlene Arens, Fraunhofer Institute for Systems and Innovation Research (ISI). 8. ASME, “General Position Statement on Technology and Policy Recommendation for Reducing Carbon Dioxide Emission for the Energy Sector”, 2009. 9. “Available and Emerging Technologies for Reducing Greenhouse Gas Emissions from the Iron and Steel Industry”, Sector Policies and Program Division, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711.