We need to preheat the steel slabs before the hot rolling process in the pusher type furnace to the temperature suitable for hot rolling, which is an expensive and energy consuming process. The pusher type furnace in our hot rolling mill represents a bottleneck, so with the idea of increasing furnace productivity, we have created a model based on computational fluid dynamics (CFD), with which we have calculated parameters crucial to us, while varying the type of fuel and the oxygen content in the air. These parameters include flame temperature, CO2 emissions, NOx emissions and soot content.
In the master’s thesis three simulations were performed for each type of fuel. Firstly we used natural gas as the fuel, which is also our current energy source in the pusher type furnace. As a potential substitute, we have considered propane, as the price and supply of natural gas is questionable in current geopolitical situation. As second substitute fuel, we chose hydrogen, as hydrogen represents the green fuel of the future. The other parameter which we were varying was the oxygen content in the combustion air. First assumed value was 21 %, which is atmospheric value. Second assumed value was 23 % and the third was 25 %.
From the simulation results, we determined the new furnace capacity based on flame temperature through thermotehnical calculations. Using the calculated furnace capacity, we could also evaluate CO2 emissions, NOx emissions and soot content per ton. Then we compared emissions with the current state and assessed whether combustion with an increased oxygen content in the air is an environmentally friendly process.
Finally, we conducted a financial evaluation by comparing the market price of still and the market price of technically pure oxygen to determine whether combustion with an increased oxygen content in the air is also economically viable.
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