Description
The batch nib drum roaster combines the benefits of high capacity nib roasting with high quality flavor development.
The nibs are gently mixed in a roasting drum. Heat transfer takes exclusively place by heat conduction, where the product has direct contact with the drum surface. As a result of the indirect heating, the product does not come into contact with combustion gasses. The heating media (hot air) is efficiently conducted around the drum, which ensures a more uniform temperature at the entire length of the cylinder. As heat transfer takes exclusively place by heat conduction, a slow drying process is achieved. During the roasting water or other solutions can be added via a spraying lance. With slowly rising temperature the moist thermal atmosphere ensures an efficient reduction of the bacterial count.
This roasting system has the advantage that recipe changes can easily be made between the different batches. Filling and emptying takes little time due to the large door inlet. The excellent insulation of the drum roaster results in a lower outer surface temperature compared to other roasting systems, including its benefits related to energy-usage. The burning gas for hot air injection is recovered via a heat exchanger, which leads to a further decrease of energy consumption.
Other advantages can be found in the drum drive. Due to the lower torque on the outgoing shaft of the gear box, the safety ratio is very high. The drum drive provides a good access for maintenance and is flexible in terms of speed. The roaster can be started/stopped with full product loaded. The hot and fresh air flows directly into the product which improves the roasting and flavor development. The BNAR is capable of handling highly moisturized nibs after alkalization.
Batch Nib Cooler
After the batch has been roasted, it is fed into a cooler, which cools down the nibs to stop the roasting process and further cooled down to the temperature which is most suitable for the liquor grinding section. Through a permeable bottom, cold air, filtered is blown in. While the nibs are continuously stirred slowly, the nibs will be cooled equally and efficiently. To prevent the permeable bottom getting polluted with sticky product the grid is “self-cleaning”. The cooler is installed on load cells and the cooling air is micro-biologically filtered. During the new cycle of roasting inside the drum roaster, this batch is cooled with cold air. After an adjustable time or temperature the nibs are pushed, with special designed wipers, out of the cooler.
