Belt dryer with two-stage heating system for eucalyptus sawdust
The Navigator Company, Portugal
Sector: Pulp and paper industry
Challenge: Compact drying system with extensive requirements. Due to the requirement to use waste heat in the low temperature range, this system is heated with two different heat sources.
Solution: Drying system with two-stage heat exchanger with a total length of 13.5 m
Dryer used: Belt dryer type BT 1-6200-13.5
Product to be dried: Eucalyptus sawdust and fines
Challenge
Strict guidelines of the EU Green Deal programme CINEA
The realization of the drying system for our customer “The Navigator Company"” presented the stela team with special challenges, which were mainly due to the detailed specifications and specific customer requirements. The drying system, which is used in the paper industry, had to meet strict specifications - from design and documentation to delivery, installation and the necessary certificates. The project was also registered with the CINEA (European Climate Infrastructure and Environmental Executive Agency). The European Executive Agency, which was established in 2021, promotes EU programs under the EU Green Deal. This made it necessary to complete the project on time as part of this EU program.
Another challenge was the two-stage heating system. The drying plant is supplied with hot water (low temperature) to preheat the outside air. The aim was to extract the maximum amount of energy from this valuable resource and thus make the best possible use of the waste heat. This heat source is low temperature hot water with a flow temperature of 45°C, which is cooled to a return temperature of 30°C. This energy source cannot be used in any other process in the plant, except in the STELA low temperature belt dryer. In a second stage, a steam heat exchanger is used which is designed to use as little steam as possible to further minimize energy consumption.
Solution
Heat transfer and moisture reduction with stela belt dryers
With an overall length of 13.5 meters, the BT dryer is a comparatively compact system. By maximizing the heat transfer surface of the low-temperature heat exchanger, a coefficient of friction of 4K is generated. The pre-heated outside air thus absorbs the maximum available and transferable amount of heat from the low-temperature system. In this way, the customer reduces the use of steam as much as possible, as the available waste heat is optimally utilized.
In the second heat exchanger stage the drying air is further conditioned to the desired value. With a drying temperature of approx. 100°C, the STELA belt dryer reduces between 6,500 and 8,400 kg of wet eucalyptus sawdust from approx. 43-54% to approx. 5% moisture within one hour.
Manufacturing and assembly
The assembly phase was subject to strict safety requirements. A safety officer was present during the entire construction phase to ensure compliance with all safety measures and to coordinate between the STELA Laxhuber teams and the customer's safety officers. Although the extensive requirements led to increased effort and an extended installation time, the system was successfully installed within a month.
A STELA lead fitter coordinated the work of a five-person installation team and the coordination of an additional safety officer. Despite the technical challenges, the installation was ultimately completed successfully, but there were special features here too: The use of a tower crane was not possible due to strict factory regulations in the area of occupational safety. In addition, a belt conveyor running directly above the assembly area would have severely restricted the use of a tower crane. As an alternative, a rotating telescopic forklift with a cable winch tip was used.
Accessibility to the assembly area was compromised by an on-site belt conveyor that crossed over above the belt dryer to be assembled resulting in a continuous discharge of dust and fine material. This required additional effort to clean and protect the components during assembly.
Conclusion and outlook
The project of our customer “The Navigator Company" illustrates how innovative drying solutions can make the paper industry more effective and sustainable. Thanks to the intelligent use of waste heat and the minimization of steam consumption, it was possible to implement a resource-saving and high-performance drying system.
Close co-operation between all the departments involved, made it possible to implement and meet the demanding contract and deadline requirements could be implemented and met.
This project not only forms the basis for an optimized production process, but also sets standards for future projects in the field of sustainable and energy-efficient plants.
Downloads
Find out more about the belt drying system type BT:
Get in contact
Contact person
Low temperature, continuous dryer, circulating dryer – not sure what’s the best choice for you? Our experienced colleagues will be happy to help you find the best solution for your product. Please feel free to contact us without obligation.
Telephone +49 8724 899-10
Email sales[at]stela.de
