Nutec Bickley is busy in its Ceramics Business Unit constructing a specialist, repeat-order kiln. The contract was awarded by a major US manufacturer in the energy field.
The kiln is a gas-fired, downdraft elevator kiln with a maximum operating temperature of 1,650 °C (3,000 °F), and it has been designed to fire performance-critical high alumina components. These are complex pieces and in some cases the firing cycle can exceed 150 hours. The kiln is expected to operate 24/7, so all elements involved have to be high quality, efficient and durable. Employing the downdraft exhaust principle enables this system to counteract the tendency for the hotter gases to accumulate at the roof of the kiln, which can cause an imbalance of temperature from top to bottom. High-velocity nozzle mix burners are employed in this elevator kiln as they result in excellent turbulence and heat transfer. The way the burners are positioned in the kiln is equally important, and it’s done in such a way so as to promote even temperature distribution and uniformity throughout the product.
These factors are important when it comes to the problem-free firing of specialty high alumina components. The kiln’s multi-temperature control zones provide flexibility and thermal management throughout the firing cycle. The company’s combustion system also allows for adjustable and programmable levels of excess air throughout the firing cycle for temperature uniformity enhancement and atmosphere control. This allows the use of excess air only when required by the process, significantly improving temperature control and fuel efficiency. There is pre-programmed smooth transition between the two modes – excess air and proportional on-ratio.
In any ceramic kiln, the role of insulation is a prime consideration. This kiln uses the Nutec Bickley floating anchor refractory support system. This system anchors the refractory to the steel wall in a way that allows expansion and contraction movement of the refractory wall parallel to the steel casing, keeping the refractories from moving away from the shell. This results in a longer service life and reduced maintenance requirements.