KHD's special solutions for AFR substitution and NOx abatement
As more and more countries adapt and benefit from proven equipment solutions for alternative fuel usage, other developing countries still do not have sufficiently developed systems for the collection, preparation and utilisation of alternative fuels. Therefore, cement producers who want to increase their alternative fuel rate and maintain a sustainable and competitive production require better and more efficient solutions, especially those who are robust enough to handle even less pre-processed waste streams. To fulfill this demand, KHD developed a rotary combustion reactor called PYROROTOR®, a product that helps plant operators to reduce alternative fuel preparation costs by the biggest possible extent.
Pyrorotor is able to process almost all kinds of alternative fuels, from the coarsest waste matter to materials with extremely poor burning properties. Even whole tires can be utilised without any distinct preparation. To achieve that, Pyrorotor constantly revolves and tumbles alternative fuel to enable a sufficient retention time in high temperature (up to 1200 °C) to ensure a complete burn-out of any material.
The presentation includes operational results of KHD´s first installed Pyrorotors at Gmunden plant in Austria and the Ssangyong plant in South Korea.
For the pilot project in Gmunden, KHD implemented the best available calciner technology for alternative fuel processing, which enables the owner, Rohrdorf Zement, to produce clinker with high amounts of low-cost alternative fuels. In South Korea, KHD successfully commissioned two Pyrorotors for high AFR utilisation rates.
Another major topic of the industry is the mandatory reduction of NOx emissions. The ever more stringent emission limits have forced many cement producers to install SNCR and SCR-technologies which can be quite CAPEX-intense. However, NOx emissions can also be greatly reduced by the appropriate design of the calciner system. To acknowledge the lowest emission guidelines across the globe, an innovative gasifying reactor system called PYROREDOX® was developed by KHD to operate plants without any costly secondary measures like SCR whilst still achieving the lowest NOx emission values.
The Pyroredox system, patented by KHD, serves as a gasifying reactor which is connected upstream of the main calciner. By separation of the gasification zone from the oxidisation zone, a reduction comparable to the catalytic SCR technology is achieved.
The presentation includes operational results from China where KHD retrofitted existing plants with Pyroredox and combined it with existing SNCR systems to achieve extremely low emission levels below 30mg/Nm3. Specifically, three plants from the Tianrui Group in Weihui, Xindeng (5.500 tpd each) and Xingyang (12.000 tpd) are mentioned. In addition to the desired results for reduction in NOx emissions as well as low ammonia slippage, it should be mentioned that Pyroredox has not shown any negative effects on production output, fuel demand and power consumption.
