Dr. Joachim von Schéele

Keynote speech title: Short-term Opportunities to Decrease CO2 and NOx Emissions from the Steel and Metals Industries

Abstract: The combustion processes in the heavy industries area are a large user of energy and source of emissions. Those are mainly applied for heating, melting, smelting, and reheating of the materials being produced. In general, China produces more than half of the world production of most main metals, for example, steel and aluminium, and two-thirds of the steel production is found in Asia. In China there are more than 120,000 industrial furnaces in operation. The energy use in those industrial furnaces accounts for more than 25% of the total energy use in China, and more than 60% of the energy use in its industry. Steel, non-ferrous metals, cement, and glass industries are the main energy users.

There are two main ways to save energy and reduce emissions in those processes: the Direct Way – the most efficient ways to save energy and decrease emissions are to minimize the need and the generation, respectively; the Indirect Way – energy recycling and post treatment to remove CO2, NOx, SOx, etc., e.g., using SCR/SNCR.

The paper summarizes the short-term opportunities to decrease CO2 and NOx emissions from the steel and metals Industries using the Direct Way. It has been proven that the need for energy in many of these combustion processes can be reduced by 20-50% by applying different types of oxyfuel combustion – an excellent example of the Direct Way. Reduction of CO2 emissions will follow the reduced energy need. A special combustion technology called flameless oxyfuel is also very efficient to reduce NOx emissions. Linde has pioneered the development and implementation of flameless oxyfuel technology in the steel and aluminium industries. Flameless Oxyfuel provides an overall thermal efficiency in the heating of 80%, air-fuel reaches 40-60%. With flameless oxyfuel, compared to air-fuel, the energy savings in a reheating furnace are at least 25%, but many times 50% or even more. The corresponding reduction in CO2 emission is also 25-50%. Savings in terms of NOx emissions are substantial, sometimes exceeding 90%. Flameless Oxyfuel combustion has major advantages over conventional oxyfuel and, even more, over any kind of air-fuel combustion. The improved temperature uniformity is a very important benefit, which also reduces the fuel consumption further. Additionally, a small off-gas volume and a high concentration of CO2 make it increasingly suitable for potential downstream Carbon Capture and Sequestration. The paper discusses a large number of examples from successful use of these technologies in industrial installations and the favourable results obtained, which are replicable in short-term across the steel and metals industries, hence contributing to a reduced environmental impact.