System technology for alternative fuels (AFR)
Old tyres, shredded tyres, plastics and other oil-based mineral products – large volumes of alternative fuels are available at low cost and can be safely disposed of using the high-temperature process in the rotary kiln systems in cement works, leaving no residues.
Alternative fuels for economical re-use in cement plants
Our systems enable these alternative materials to be stored, separated, weighed, metered out and transported efficiently and without harming the environment. It is also possible to change fuel types.
These plants thus ensure that kilns in cement works are operated and fuelled much more economically. At the same time, the ash from the alternative fuels is added to the mineral components of the cement clinker and thus reduces the volume of additives needed.
Using alternative fuels
Pre-processing of waste into a high grade alternative fuel and its application is becoming increasingly attractive to reduce production costs and CO2 emissions – especially for energy-intensive areas like the cement and lime industry. Furthermore, all organic pollutants will be destroyed in the kiln at temperatures of approximately 2,000 °C and will be absorbed by the surplus of finely ground limestone. The use of different types of alternative fuels is governed by the availability in a given region and especially the economic aspects.
Our AFR systems are designed to meet the particular requirements of functionality and performance under the strain of daily operation. In addition to a comprehensive supply of reliable systems for handling alternative fuels, we also focus on planning of logistics and customized conveying and warehouse systems, including crane halls, steel structures and of course turnkey deliveries of mechanical part. Due to the modular system of all design groups and system components, each project is engineered and designed individually.
The importance of flexibility and reliability
The alternative fuel markets are still developing. It is in the interests of the plant operator to prefer solutions which could be continually and easily customised to use the of most efficient and economical fuel.
The thermal substitution rate (TSR) also has a significant effect on the overall design of the system and the components used. The higher the required and achieved TSR, the greater the need for reliable equipment, because the substitution of primary fuel is very difficult due to technological and economical aspects.
System technology for scrap tires as alternative fuel
Scrap tires that cannot be recycled are best for co-processing: Natural rubber and textile carcass can be used as a fuel, whilst the steel carcass donates iron to the required clinker composition. BEUMER Group has many years of expertise and sophisticated technologies for feeding whole tires as well as chipped tires as tire derived fuel (TDF).
Chipped tires as tire derived fuel (tdf)
Our system technology is flexible and also designed for conveying and feeding TDF for a continuous and smooth kiln operation. TDF can constantly be fed on the same path as RDF and biomass, when the longer retention time of tire chips is taken into account for proper coprocessing. All modules and system components, as well as each entire project, are planned individually according to the specific process requirements.
A continuously running kiln process is necessary to produce a constant cement clinker quality, which requires a continuous feeding of scrap tires as well as tire chips. An automatic handling system is recommended, due to the large quantities to be burnt without peak load. The electrical control is equipped with a PLC. All storage and supply functions are controlled by means of photocells and sensors insensitive to dirt, dust and temperature. The drives are furnished with inspection switches so that in case of disturbances a single segment can be handled manually.
From delivery to co-processing
After the scrap tires are unloaded, they are handled primarily by a wheel loader or gantry crane with a polygon gripper for storage and discharge. The size of the stock area has to be adapted to the kiln consumption and works as a compensation between discontinuous supply and continuous consumption.
Official permission must be obtained for setting up and operating the storage as well as for building the tire handling system, and the corresponding local regulations regarding fire-fighting and water management should be followed.
Once the tires have passed the storage and separating line, control station and weighing system, steeply inclined conveyors transport them from ground level to the defined inlet height at the preheater. The capacity and size of the incline conveyor are specifically designed in accordance with each particular project.
The whole tires can be fed through a swivel valve or triple flap. The upper and central steps open and close in order to protect the pyroprocess against heat loss and unwanted air entry. The lower step acts as a shutoff device for malfunctions. The metallic parts are protected by a highly heat-resistant coating.
Competent engineering, fast and reliable on-site service as well as optimal spare parts supply round out our offering and ensure high reliability of the systems.