Usage of waste as fuel in the cement industry

In order to generate sufficient energy for the production of cement, waste is often used in cement plants for incineration and heating of the plants. This way, waste can be used as thermal energy. The company FCC Medio Ambiente was the ideal partner for the cement plant in Alicante when it came to procuring fuels for cement production.

FCC Medio Ambiente is the company of the FCC Group, which has been providing environmental services for more than 110 years. It serves 66 million people in more than 5,000 communities worldwide. It manages more than 23.5 million tons annually through a network that includes more than 200 environmental recovery and recycling systems.

To be able to optimally process the required waste, in this case plastic waste particles with a maximum size of 50 millimeters (RDF), for incineration at the Alicante cement plant, moisture within the particles must be removed. For this purpose, FCC Medio Ambiente turned to the leading Bavarian manufacturer of drying equipment, Stela Drying Technology, in June 2020.

The contact with Stela was established in 2020 by R&B Recycling and Biomass Plants. R&B is a specialist in machinery and equipment for recycling and biomass. After some talks held a few years ago between FCC Medio Ambiente and R&B about the possibilities of cooperation, this was a wonderful opportunity to reestablish the contact. With Stela Drying Technology as a specialist for low-temperature drying of bulk materials and biomass, R&B has the ideal partner to meet FCC Medio Ambiente's requirements. The family-owned company Stela will celebrate its 100th anniversary in 2022 and has specialized in the development, manufacture and optimization of belt drying systems for several decades. Thanks to the new production facility built a few years ago in Lower Bavaria, most of the components for the drying systems can be designed and manufactured in-house.

Together with FCC Medio Ambiente, the experienced engineers at Stela Drying Technology developed a belt drying system individually tailored to the needs on site. Due to the pugnacity of the waste and the difficult conditions on site, some special features had to be included in the design and material selection for the dryer.

The entire system is made of stainless steel to prevent corrosion from the material being dried and the salty air near the coast, and to enable a long durability of the drying system.
Regional conditions such as a high ambient temperature in Spain and high humidity must also be taken into account when determining the required drying capacity.

Finally, a BTL 1 / 3000-18 dryer with a width of three meters and an active length of 18 meters will be installed in Alicante. With an input of 5.5 tons of RDF per hour, FCC Medio Ambiente obtains a production of 3.7 tons of dry material per hour. This corresponds to a water evaporation of 1.8 tons per hour.
Pure water is used to heat the plant, providing the necessary heat via five heat exchangers at an energy requirement of approximately 2 MW.

Another challenge for RDF drying systems is odor emissions. Heating and ventilating the drying material can create an unpleasant odor that is released into the environment without if there are no proper precautions installed. For this purpose, in collaboration with FCC Medio Ambiente, Stela has developed an interface that directs the exhaust air from the drying process to an existing pipe system of FCC Medio Ambiente, equipped with a biofilter that guarantees the cleanliness of the used air. This reduces odor emissions into the environment to a minimum. The dryer is equipped with a rotating mechanism that ensures homogenious drying by regularly moving the plastic particles. It also has an extinguishing system and an automatic web cleaning system.

After completion of the system installation in July 2021, the electrical installation and final commissioning of the drying plant will take place in the following weeks.

Original report: https://www.retema.es/revistas/julio-agosto-Otuce page 88

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