Summary

SF Beton in Appeltern, the Netherlands, produces concrete paving bricks in various colours, shapes and sizes. Overall production capacity is approx. 3,900 planks of stacked bricks per day.
Concrete acquires its qualities by a drying process in conditioned surroundings. SF Beton has completely changed its drying method by applying a first-in-first-out approach.
Formerly, forklift trucks stacked the planks with bricks in a drying chamber. The first plank to be inserted always came out last, thus varying the drying time (and conditions) between the first and last planks to be inserted and subsequently unloaded. All applied heat was lost when the drying chambers were opened.
The new approach to drying not only ensures substantial energy savings but also reduces operating costs and the amount of production waste owing to variations in colour. The drying chambers are located in a closed conditioned compartment. The planks are inserted and removed through slits in the wall. Carriages on rails with a lifting device take the planks and stack them automatically in the drying chambers. When ready, another carriage removes the planks and transports them to the exit. The whole process is completely automated. Blowers operating on the venturi principle have been installed to ensure that both the upper and lower stacked planks receive fully saturated air at the same temperature (25 °C). Thus a temperature difference of less than 1 °C can be maintained between the bottom and the top of the drying chamber. Maintenance and labour costs have been significantly reduced compared with the forklift truck operation previously adopted.
Applications can be found in industrial processes and in companies using a drying process, especially the concrete and ceramics industries.