Study of biomass applied to a cogeneration system: A steelmaking industry case

In this paper, a theoretical technical study was carried out using Brazilian available biomass materials (rice husk, coffee husk and elephant grass) compared to natural gas applied to an electric arc furnace (EAF) steelmaking process. Rice and coffee husk are biomass residues from the agriculture while elephant grass (Pennisetum Purpureum Schum) is an abundant, fast growing plant, which is used for cattle breeding. The ultimate analysis of the biomass materials was carried out in the research department of a Brazilian Steelmaking Industry. The results of the ultimate analysis were used to determine the lower calorific value and the mass flow rate of the biomass materials used in the cogeneration system. The actual steelmaking process uses natural gas to both improve the “cold spots” inside the furnace and contribute to minimize the use of electrical energy in the heating process. The feasibility study considers a combined heat and power plant (CHP) to generate electricity and heat to the electric arc furnace (EAF) process. This study used the First Law of Thermodynamics to determine the operational parameters of the cogeneration plant considering three cases of different operational parameters in the Rankine cycle. The technical results show that the natural gas consumption and exhaust gas generation were the lowest among the fuels in the three cases analyzed. Regarding the exhaust gases generation, some aspects should be highlighted: the combustion of biomass is considered carbon neutral; the exhaust gases generated may be used to scrap preheat; also, biomass is a renewable fuel in contrast with natural gas, which is a fossil fuel. Thus, an economic analysis, considering only the operational cost of the plant, was conducted exhibiting that elephant grass had the lowest operational cost, accounting for a reduction of about 9% in the second case and 15% in the third case compared to natural gas. Although the biomasses have lower LCV than natural gas, they showed a great promise of their use in the EAF process indicating their feasibility as an excellent alternative for the process of producing iron.

[1]  Marcus Kirschen,et al.  Influence of direct reduced iron on the energy balance of the electric arc furnace in steel industry , 2011 .

[2]  Ernst Worrell,et al.  Energy Intensity Development of the German Iron and Steel Industry between 1991 and 2007 , 2012 .

[3]  Tengfang T. Xu,et al.  Reducing energy consumption and CO2 emissions by energy efficiency measures and international trading: A bottom-up modeling for the U.S. iron and steel sector , 2014 .

[4]  Peter McKendry,et al.  Energy production from biomass (Part 1): Overview of biomass. , 2002, Bioresource technology.

[5]  Ünal Çamdali,et al.  Exergy analysis and efficiency in an industrial AC electric ARC furnace , 2003 .

[6]  Xiang Yin,et al.  A bottom-up analysis of China’s iron and steel industrial energy consumption and CO2 emissions , 2014 .

[7]  Vladimir Strezov,et al.  Defining sustainability indicators of iron and steel production , 2013 .

[8]  Geoffrey P. Hammond,et al.  Heat recovery opportunities in UK industry , 2014 .

[9]  Magdalena Zaharia,et al.  Recycling Agricultural Waste from Palm Shells during Electric Arc Furnace Steelmaking , 2012 .

[10]  G. Scotti.  Prospects for energy saving in the Italian iron and steel industry using electric furnaces , 1990 .

[11]  Nils Schüler,et al.  Development of a thermal oil operated waste heat exchanger within the off-gas of an electric arc furnace at steel mills , 2014 .

[12]  Aie.  World Energy Outlook 2007 , 2007 .

[13]  Kari Sipilä,et al.  Small-scale Biomass CHP Technologies : Situation in Finland, Denmark and Sweden , 2004 .

[14]  Marco Vannucci,et al.  Reducing the energy consumption and CO2 emissions of energy intensive industries through decision support systems – An example of application to the steel industry , 2013 .

[15]  G. M. Prine,et al.  Dry matter accumulation of elephantgrass, energycane, and elephantmillet in a subtropical climate , 1993 .

[16]  Gavin M. Mudd,et al.  The steel industry, abiotic resource depletion and life cycle assessment: a real or perceived issue? , 2011 .

[17]  Magdalena Losowska,et al.  Embodied energy counting of sustainable heat, power and steel processes , 2011 .

[18]  R. Teodoro da Costa,et al.  Charcoal, renewable energy source for steelmaking process , 2006 .

[19]  R. C. Gupta,et al.  WOODCHAR AS A SUSTAINABLE REDUCTANT FOR IRONMAKING IN THE 21ST CENTURY , 2003 .

[20]  B. Jenkins,et al.  Combustion properties of biomass , 1998 .

[21]  Semida Silveira,et al.  The impact of climate targets on future steel production – an analysis based on a global energy system model , 2015 .

[22]  Linghong Zhang,et al.  Overview of recent advances in thermo-chemical conversion of biomass. , 2010 .