Siti-B&T Group: The roller kilns for firing latest-generation ceramic products

The roller kilns for firing latest-generation ceramic products developed by the SITI – B&T group are highly innovative, particularly in terms of performance (especially for high production capacities), automation, efficiency, energy saving and management costs. They come with large entrances, up to 3.2 metres in width, and may be up to 200 metres or more in length.
This has allowed the internal temperature distribution to be optimised through the use of new types of burners and flame ports for the firing and cooling zones, while other improvements have been made to the cooling zones. This has yielded excellent results in terms of calibre, flatness and colour tones. This is particularly evident in products such as porcelain tile, although single-fired and monoporosa tiles have shown an improvement in tolerance of two tenths of a millimetre in medium and large tile sizes
For this reason, a whole new series of devices and automatic management systems have been added to continuously control the various parameters that affect flatness, cracking and residual tensions in the pieces, especially when processing large and thick tiles.
Even in the event of changes in load (full/empty or cycle variations), the pressure and temperature stabilise automatically, allowing the kiln to remain perfectly stable during pre-heating and cooling and providing a cooling capacity of more than 10% without risk of breakages or rejects when production resumes. The product arriving from the kiln feeding line is always in excellent condition.
The combustion air pipes run outside the modules to facilitate access and modification or maintenance work and improve thermal insulation. Furthermore, the insulation of the modules using eco-friendly materials ensures that the external temperature of the kiln is no more than 40°C higher than ambient temperature. To make it easier to clean the firing channel, the openings on the sides of the kiln have been enlarged. This includes both the hatches under the rollers and the inspection points at the top.  
The fixed air and modulated gas combustion system reduces consumption and allows for temperature uniformity in the firing section with a maximum differential of 5°C up to kiln widths of 3200 mm.
As well as being highly flexible and suitable for firing any type of ceramic tile, the kiln developed by the SITI – B&T Group also has a lower environmental impact thanks to the use of eco-friendly fibres and insulating materials. Energy recovery systems for exploiting the hot air recovered from the cooling zones have also been introduced.
Major improvements in terms of increased productivity have also been achieved with the multi-drive type roller drives, consisting of inverter-controlled gear motors installed every three kiln modules with completely dry operation which bring advantages in terms of cleaning and maintenance.
This drive system allows for uniform product movement at differentiated speeds to compensate for the spaces deriving from product shrinkage. It also allows for a forward-backward movement, which when necessary stops the forward movement of the products without causing the rollers to stop rotating, thereby reducing the risk of roller deformation.