More sustainability for the cement industry

Güllü Beydilli

#grey2green – the quiet revolution of the cement industry

Climate polluter cement? How we make cement plants ready for the Green Deal - with the polysius® product family from thyssenkrupp Industrial Solutions.

The cement industry is one of the world’s largest emitters of greenhouse gases such as CO2. Cement manufacturers are under increasing pressure to become more sustainable. A rethink is needed – coupled with the necessary technologies and solutions that can be integrated into existing cement plants.

With the polysius® product family, our experts at thyssenkrupp Industrial Solutions are waiting with product solutions for more sustainable clinker production through to more efficient use of alternative fuels for cement kilns.

Lower CO2 cement production with activated clay

Clinker is the most important component in making cement a hydraulic binder. For years, cement manufacturers have been striving to reduce the so-called clinker factor – the proportion of clinker in cement – by adding additives. This is because the higher the proportion of clinker, the more CO2 is released during cement production.

The polysius® activated clay technology developed by thyssenkrupp makes it possible to reduce CO2 emissions from cement production by up to 40 percent. Part of the cement clinker is replaced by calcined, i.e. thermally activated, clay. The first large-scale plant with activated clay technology is scheduled for completion in fall 2021. This will save more than 120,000 tons of CO2 per year.

Making plants ready for alternative fuels

Fossil fuels – such as oil, gas or coal – burn well and are therefore widely used. However, they have one major drawback: their not inconsiderable CO2 footprint. With polysius® fuel substitution solutions, cement plants can run on up to 100% alternative fuels, such as those derived from waste and biomass.

From waste-intensive pretreatment with the polflame® burner to zero pretreatment with the prepol® SC step burner. Our solutions enable the combustion of fuels directly in the calciner or in a separate combustion chamber.

The task of the sintering zone burner or main burner is to generate a defined temperature profile in the kiln to ensure an optimum sintering process of the clinker.

The polflame® clinker zone burner makes it possible to exploit this potential of alternative fuels to the full. In the past, clinker zone burners were only designed for fossil fuels. Alternative fuels could, if at all, only be used with great losses. Thanks to polflame®, alternative fuels are now in no way inferior to fossil fuels in terms of efficiency.

Thus, the second generation of polflame® offers an ideal solution for dealing with difficult fuels and, at the same time, maintenance-free nozzle adjustment, ease of operation, improved efficiency and a reduction in the CO2 footprint of the entire cement plant.

A view into prepol® SC.

Waste management with prepol® SC

Low-grade alternative fuels that previously had to be landfilled or taken to the waste incineration plant can be used with much greater efficiency with the prepol® SC step burner. The waste can burn for more than 1,000 seconds at high temperatures. Compared to conventional calciner technologies with a maximum residence time of seven seconds, the prepol® SC thus opens up a new dimension for the thermal utilization of a wide range of alternative fuels.

In addition to conserving natural resources and reducing emissions, this also significantly lowers operating costs. This is made possible by the use of a wide variety of waste types, low quality requirements, and low processing costs. Another factor is that 80 percent of the thermal energy generated in the combustion chamber can be used directly in the process. And the ash that remains is also recycled into material.

CO2 guzzler clinker production?

Another factor in the high CO2 emissions in cement production is the limestone used in clinker production, which is, however, indispensable for the cement industry: large quantities of carbon dioxide (CO2) are released during cement production. Only one third of these CO2 emissions result from the combustion of fossil fuels such as coal or petroleum coke, while the majority is released by the decomposition of limestone. Limestone – the most important raw material for cement production – consists of 35 to 44% CO2, depending on the quality – not particularly beneficial for the CO2 footprint of the cement industry.

More sustainable clinker production with polysius® pure oxyfuel

Oxyfuel technology replaces ambient air in the clinker production process by introducing pure oxygen into the front zone of the cooler. Since the nitrogen content of the air is no longer present, the CO2 concentration in the kiln exhaust gas can be increased up to 100%. CO2 is thus better isolated and more suitable for later use and storage. In other words, the CO2 can be captured more efficiently and does not escape uncontrolled into the atmosphere.

Animation of a polysius® pure oxyfuel plant.

In contrast to the first-generation oxyfuel process, polysius® pure oxyfuel offers optimizations that make integration into existing cement plants easier, more intuitive and more attractive for our customers. More about polysius® pure oxyfuel here.

Step by step to more sustainability

There is no one-size-fits-all solution for green cement production. Instead, many adjusting screws must be turned along the entire production chain. There is potential for optimization in every production step and every machine. With the polysius® product family, we offer cement manufacturers solutions that can be integrated immediately to make their plants more environmentally friendly today. After all, sustainability is not just an end in itself for cement producers, but necessary to remain competitive – especially in view of regulations such as the EU Green Deal.