Eggersmann FUEL: The custom solution for the cement industry
Landfill diversion, lower consumption of virgin fossil fuels, lower CO2 emissions –
alternative fuels derived from municipal solid waste (MSW) offer many advantages,
but they are rarely adjusted to the needs of the customer. The Eggersmann FUEL is
different. It is directly customised to the requirements of the cement industry
to compensate as much fossil fuel as possible.
Tackling ambitious plans
The cement industry has ambitious plans. This is demonstrated not only by the roadmaps of the Global Cement and Concrete Association (GCCA)1 and the International Energy Agency (IEA)2, but also by the self-imposed targets of many cement companies. According to their own statements, many of the major global producers want to increase the use of alternative fuel up to a total of 25% to 55% by 2030.3 These ambitious goals call for practical solutions that can already be implemented today if these targets are to be achieved. But the quality of the alternative fuels varies greatly depending on the way the waste is treated. With the Eggersmann FUEL, Eggersmann Anlagenbau offers a proven process that is specifically orientated towards the needs of the cement industry. It involves biological drying before the usual mechanical processing, which enables a much more targeted treatment of the MSW. “At Eggersmann, we are more than just a recycling company. Our group is made up of the business units’ construction, recycling and composting. The Eggersmann FUEL is therefore a holistic solution: We looked at the subject through the eyes of the construction industry based on our experience in mechanical recycling and composting of bio-waste,” explains Eugen Becker, Business Development Manager at Eggersmann, the Group‘s synergies. The result is an alternative fuel with ideal values for usage in the clinker kiln in terms of moisture, ash, sulphur and chlorine.
Water content: the great quality challenge
The extraction of alternative fuels from MSW for the cement industry faces a major challenge worldwide: the high proportion of biomass. If the country or region in question does not yet have an appropriate waste separation system at source, the proportion of biological waste and therefore the moisture in MSW is very high – in many countries the water content is even over 50%. Alternative fuels are of interest to waste disposal companies because they reduce the mass to be landfilled, while the cement industry sees them as a means to reduce the consumption of fossil fuels. If the MSW is only processed mechanically, both of these goals must suffer due to the water inside the biomass. On the one hand, still moist fuel is a problem for the cement industry, as water vapour is produced during combustion. This vapour expands, occupies volume in the kiln system and causes a higher pressure-drop. Consequently, only a very limited amount of alternative fuel can thus be used. Due to the increased exhaust air volume inside the system an operation at full clinker capacity will not be achieved. Additionally, the energy for the water evaporation needs to be provided resulting in an increase of the specific thermal energy consumption of the clinker kiln. This is detrimental to the cost-benefit calculation. Creating an appropriately dry alternative fuel solely mechanically will hinder landfill diversion on the other hand. The water content makes the biomass very sticky and turns the separation into a difficult task. The carry-over rate therefore leads to a significantly higher moist biomass content in the RDF. At the same time, a lot of separated organic is disposed which creates considerably more landfill mass – exactly what the disposal companies want to avoid with the production of RDF. To put it in a nutshell: With the common treatment processes there is more waste to be landfilled for the disposal companies as well as a moist fuel, that is still energy intensive to burn for the cement industry. The tried and tested Eggersmann FUEL process offers an efficient way to meet this challenge by optimising the MSW for treatment in the clinker kiln through biological drying.
Optimised fuel for the clinker kiln
In the Eggersmann FUEL process, the pre-shredded MSW is dried biologically in a robust and fully controllable manner. The drying process consists of three components:
1) Concrete lanes with floor ventilation and drainage system
2) CONVAERO membrane to cover the lanes
3) Automated BACKHUS CON turning technology
Utilising the natural heat of up to 70 °C from the composting process, the water content from the MSW is vaporised through the membrane. An external heat supply is not necessary – only ambient air is fed in to optimise the growth of the necessary microorganisms. The semi-permeable membrane allows the water to evaporate, but at the same time prevents rainwater from entering or unpleasant odours from escaping. Leachate is collected by the drainage system. Regular turning with the BACKHUS CON homogenises the material and creates favourable conditions for the microorganisms. It has been proven that the water content can be reduced from around 55% to below 20% within just 21 days. At the same time, the net calorific value increases from approx. 2500 kJ/kg to around 14000 kJ/kg and above. Although the biomass could now also be sorted out mechanically more easily, this is no longer necessary. At 20% moisture the biomass itself has now become a fuel. At this point 1 t of Eggersmann FUEL contains sufficient energy to burn 4 t of cement clinker and to replace 0.5 t of high-quality coal. Up to 100% alternative fuel can be used for combustion in the clinker kiln and the operation with a thermal substitution rate above 90% has already been successfully proven in Europe. As the biomass is a renewable raw material, the Eggersmann FUEL is also more sustainable than fuels without dried biomass. But the main advantage of the Eggersmann FUEL is something else: The integration of biomass into the fuel can be positively counterbalanced when calculating the mandatory CO2 levies, which results in a clear economic advantage.
Advantages for the disposal company
For the responsible waste disposal company, Eggersmann FUEL means significantly increased landfill diversion. Even without processing into an alternative fuel, the mass of MSW can already be reduced by 50% through drying alone. As an alternative fuel for the cement industry, it can even reduce the landfill mass by as much as 80%. The fully automated BACKHUS CON turners, which turn the material and at the same time pick up the previous membrane at the front while simultaneously laying down a new one at the back, simplify the drying process considerably. They guarantee the economic efficiency as well as a defined safe operation. In addition, other recyclables and valuable components – such as metals – can be sorted out for resale as required. The fact that a large proportion of the water evaporates through the membrane also means that less leachate needs to be treated.
Modular and economical
“Our process has a modular structure and can thus be customised to suit different budgets as well as the actual demand from the regional cement industry. The number of lanes, the lane length and the lane width – these are all factors that we can adjust to the individual needs. We therefore offer turners for 6, 8 and 10 m”, explains Becker. “Whether industrialised or emerging, our process is attractive for any country that still primarily landfills waste and has a corresponding industrial demand.”
