The new Coating Centre saves a lot of energy in the coating process of a trailer chassis, as innovative technologies are being used to avoid waste heat and to utilise what has been created. It has already received an award from the German Energy Agency prior to commissioning for this, as well as further efficiency measures in all processes.
he German Energy Agency (Dena) has awarded the new Coating Centre from Krone as a pioneering project for the reduction of waste heat. Krone uses state-of-the-art production technologies to significantly reduce CO2 emissions: by around 40 percent. “We’ve achieved this outstanding result primarily through the intelligent combination of various efficiency measures in this design,” explained Mathias Schrigten, the industrial engineer at Krone responsible for the waste heat concept of the Coating Centre.
Where possible, heat loss within the Coating Centre is avoided or recycled for use elsewhere within the plant. The new building enables the responsible use of resources and sustainable operation of the entire industrial plant.
HEAT USE FROM PASSIVE COOLING
In order to achieve the desired results when blasting the surfaces, the workpieces must be supplied to the blasting system dry and heated to room temperature. For this purpose, the heat emitted to the ambient air by the chassis during cathodic dip painting (CDP) and powder cooling is fed to the raw chassis buffer. The blasting system is also designed so that the exhaust air, which is heated and filtered during the process, flows back through the building. Highly efficient drives and turbines, as well as high-performance filters, are used to reduce pressure loss.
A heat exchanger installed at the thermal oxidiser (TO) ensures that the heat generated during the cleaning process of the CDP furnace exhaust air heats the process tanks in the bath station. The powder furnace also produces waste heat, for example, when the doors are opened. Each furnace chamber now has its own burner: This means that the output can be individually regulated and adjusted during entry and exit as well as during empty runs. The retention time of the workpieces and the temperature can be adapted exactly to the requirements of the respective workpiece for each furnace chamber.
The Coating Centre also saves energy during transport, thanks to lighter goods carriers: The chassis are moved through the complete system on such carriers. For transport through the bath station, a separate main product carrier circuit was also implemented, which cycles the chassis with the light goods carrier from tank to tank. The main product carrier does not have to enter the furnaces. The weight-saving also has significant advantages in the furnace processes: The lighter the product carrier, the less mass needs to be heated or cooled. After the processes in the furnace, the waste heat from the cooling process is fed through a sophisticated ventilation system into the raw chassis buffer to heat up the chassis.
All these measures add up to a considerable amount of savings. By honouring lighthouse projects, Dena wants to make the considerable energy efficiency potential through waste heat avoidance and utilisation more visible – and motivate companies in all industries to tap this potential.
PRECISE CONTROL OF NUMEROUS PROCESSES
In addition to the measures for waste heat utilisation, Krone has implemented many other optimisations for energy efficiency in its new Coating Centre: For example, the heated tanks for pre-treatment and their pipes were more heavily insulated in the new building, so that heat requirement can be reduced, among other things. When the system is not coating, the heated tanks are automatically covered.
The circulation of the processing substance can also be controlled more precisely in each bath station. All circulation pumps are operated with frequency converters which reduce the process to a minimum if there is no workpiece in the tank. The new CDP furnace system saves additional energy thanks to new technology that hardly lets any residual heat escape when new chassis are inserted. Among other things, airlock blowers were installed for this purpose. And because there are ten CDP furnaces, the furnace chambers are only heated when they are needed for the process.