The correlation of NOx emissions with process parameters for EAF steelmaking is not well understood. As a result, environmental permitting is based on nominal emission factors which often do not take into account the plant specific equipment or operating practice. Therefore, many plants are uncertain whether they will be able to achieve satisfactory NOx emissions for present operations and are also unable to predict the impact of future changes in operating practice on NOx generation.Stantec Global Technologies Ltd., (Stantec) and Praxair, Inc. have conducted: several studies of NOx emissions at steel plants around the world, including shops using Praxair's CoJet (TM) gas injection system. The results indicate that oxygen Injection equipment, process operation and fume system design may play a far more significant role in NOx emissions than nominal production rates. Control of oxygen injection practices and furnace atmosphere chemistry can inhibit NOx formation while also offering potential process consistency. It has been demonstrated that the most cost effective first step is to review the potential for process based NOx abatement. Step 2, if required, would be to consider the expensive and largely untested "end-of-pipe" control technologies.This paper will review plant-based experience in assessing NOx generation patterns as well as providing a review of modeling techniques used to develop abatement strategies. This should provide a framework for steel plants to develop their own pro-active NOx assessment and abatement strategies.

The energy intensive nature of electric a re furnace (EAF) steelmaking necessitates that efforts to reduce greenhouse gas (GHG) emissions will affect steelmakers directly and/or through electric power producers. A model of GHG emissions from an EAF meltshop has been developed using the life cycle assessment approach. Direct and indirect sources of GHG gas emissions are estimated and ranked, Furnace combustion optimisation was evaluated in case studies conducted on a Canadian conventional EAF and a British scrap preheating 'shaft' furnace. The analysis assumed 32 and 68% fossil fuel electricity generation, respectively. These case studies show that indirect GHG emission sources, in particular electricity generation, are more significant than direct emissions from the EAF. For the conventional EAF, off gas analysis and improved combustion control reduced electricity consumption by 40 kWh t(-1), costs by US$1.05/t, and GHG emissions by 20 kg CO2-eq./t, For the shaft EAF, real time offgas monitoring and closed loop burner control reduced electricity consumption by 25 kWh t(-1), costs by US$3.6/t, and GHG emissions by 15 kg CO2-eq./t. The case studies show that combustion optimisation using an EAF off gas analysis and combustion control system provides greater electricity, cost, and GHG reductions than previously reported in the literature, I&S/1492.

Stantec Global Technologies Ltd., (Stantec) has implemented the Goodfellow EFSOP (TM) control system at Deacero, Saltillo. The Goodfellow EFSOP (TM) system includes analysis of off-gas chemistry and closed-loop control of freeboard oxygen injection, both through the existing burners and the CoJet (TM) oxygen injection system. The system has been on-line since August of 1999 with operating data from more than 4000 heats.In addition to energy savings from the control of furnace combustion, Deacero and Stantec have also been working on overall control of chemical energy sources in the furnace. Elements such as: decarburization rate, carbon usage, scrap mixture, burner firing rate and yield have been analyzed to determine the least cost operating practice for different operating conditions. The off-gas analysis system, in combination with the Goodfellow EFSOP (TM) data acquisition and analysis system have been key tools in this analysis.The results of the Goodfellow EFSOP (TM) system have been very impressive. Through a combination of process changes and closed loop control of freeboard oxygen, monthly average electricity consumption has been; reduced from 320 kWh/tonne to 285 kWh/tonne on a charge basis. Stantec and Deacero have also been able to identify the least cost operating scenarios for different production requirements. Depending on the level of productivity required, cost savings of $3 to $5 / billet tonne have been achieved which includes a savings from improved yield and productivity.This paper will include practical plant experience to demonstrate the benefits of the Goodfellow EFSOP (TM) system.