voestalpine starts up world’s most advanced sinter offgas cleaning system

• Highest-capacity sinter offgas cleaning system in productive use for first time 
• Dust, sulfur dioxide, heavy metal and other harmful offgas components reduced by some 90%
  
  

voestalpine sweeps ahead in environmental and process engineering with a newly developed sinter plant scrubber at its works in Linz, Austria. The MEROS plant now successfully brought into operation cuts emissions of dust, sulfur dioxide, heavy metals and various organic compounds by an average 90%. MEROS stands for ‘Maximized Emission Reduction Of Sintering’ and is currently the world’s most advanced and effective system for reducing sinter plant emissions.

Each year, voestalpine Stahl GmbH produces nearly three million metric tons of sinter, a key ingredient in the feed for the blast furnace process. In a sinter plant, a mixture of iron ore fines, recycled process materials and other feedstocks coalesces into a form suitable for use in a blast furnace. Much of the challenge in cleaning up the offgas stream from a sinter plant lies in the specific make-up of the emissions, which is also why such plants are an environmental concern. Conventional technologies are not up to today’s stringent emission standards.

In response to this challenge, voestalpine and Siemens VAI have jointly developed an innovative process that is far better than previous systems at filtering out all harmful substances from sinter offgas. The heart of the new system is a reactor, 56 m tall and 10 m in diameter, containing the latest in filter, blower, electrical, and instrumentation and control technology. MEROS is a multiple-stage, dry-type process in which dust and harmful metallic and organic components are bound and almost completely removed from sinter offgas by injecting adsorbents and desulfurization agents at high speed into the offgas stream. Cleaning efficiency rates include over 95% of heavy metals and over 97% of dioxins, and dust is reduced to a tenth of its previous level. Besides far larger emission reductions, another major advantage over the scrubber technology used since 1993 and now replaced by MEROS is that there is no scrubber water to dispose of.

The MEROS plant treats a million cubic meters of sinter gas per hour—the volume of a building 100 m square and 100 m tall. Or to take another comparison, the hourly cleaning capacity of the MEROS system is equivalent to the air in 112.5 million soccer balls—that’s one for every citizen of Germany, Austria and the Netherlands in the run-up to the 2008 European Cup.

About 250 sinter plants are in operation around the world, including some 70 in the European Union. Most do not feature the latest technology.

MEROS, in contrast, is the third pioneering technology in sinter offgas cleaning systems developed and brought into operation on an industrial scale by voestalpine Stahl GmbH. The Airfine fine scrubber system went online back in 1993. In 2005, there followed the eposint (Environmental Process Optimized Sintering) waste-gas recycling process, a precursor to MEROS that achieved an approximately 10% cut both in dust and sulfur dioxide emissions and in the amount of fossil fuel used despite a 30% gain in output.

These new technologies reaffirm voestalpine Stahl GmbH’s international role as an environmental pioneer in the steel industry. Other successes include the company’s Blast Furnace A, built in 2004—the most environmentally sound and energy-efficient ironmaking unit of its kind in Europe, consuming the smallest quantities of reducing agents (coke, fuel oil, etc.) and thus generating the lowest CO2 emissions compared with its peers. This year saw a further blast furnace come online where waste plastics in place of fossil fuels are processed into a reduction agent for use in the blast furnace process. This technology, once again a new development and deployed for the first time under process conditions, cuts CO2 emissions at the Linz works by a further 400,000 metric tons a year.

This continues a decades-long record of environmental achievement at voestalpine. Dust emissions, for example, have been reduced by over 80% and are set to decrease by another 50% by 2010 despite a 30% gain in production capacity under a capital expenditure program at the Linz location. Sulfur dioxide emissions have likewise been nearly halved since 1990. CO2 emissions per metric ton of crude steel have fallen by nearly 20% over the same period and by more than a third since 1980.

 

(24.10.2007)