Advanced Combustion for Advanced Ceramics

The Project

NUTEC Bickley has been commissioned to supply and install a 125f-long tunnel kiln for an advanced ceramics manufacturing client. This will be the second NUTEC Bickley kiln for this facility.

The new tunnel kiln is designed for the debinding, sintering, and cooling of specialist ceramic cores used in the aerospace industry, and will be installed and commissioned over Q4 2022 and Q1 2023.

“We are especially proud about any repeat order,” said NUTEC Bickley ’s Ceramics VP, Alberto Cantú, “but even more so in this particular case as the customer chose to have our advanced ecombustion concept integrated into the proposal.”

“This proprietary system is a revolutionary control algorithm and methodology designed for fuel savings in gas-fired tunnel kilns, and we are convinced that this installation will perform even better than the kiln we have already supplied.”

The new kiln has an operating temperature of 2190°F (1200°C) and has been designed to work 24/7 year-round.

It has 28 kiln cars in total – 22 inside the kiln and 6 on the return tack and in waiting positions –. The cores will be fired in saggars, with typically 20kg (45lb) per saggar and a total load per kiln car of 980kg (2160lb).

Uniform heating of the ware throughout the firing cycle is guaranteed, with the burners arranged to fire horizontally into the combustion space below the ware in the preheat area, and below and above the ware in the main heating zones. The burners are installed in a staggered configuration to provide turbulence within the tunnel and improved temperature uniformity throughout the product.

Energy Efficiency & ecombustion

The most efficient use of energy inputs is obviously crucial to any such installation. Typical energy recovery systems comprise the use of preheated combustion and the use of a hot air recuperation system. ecombustion offers even more efficient firing techniques and has a very real impact on operational costs.

Tunnel kilns are by their nature efficient considering their walls are heated once, avoiding an energyconsuming warm-up and cool-down process with each cycle.

However, tunnel kilns also offer greater potential for internal heat recuperation, by reusing the air used to cool down the ware as high-temperature preheated combustion air within the kiln.

Tunnel kilns also have the benefit of transferring heat to the product by controlling the flow of hot combustion products from the hot zone down to the exhaust zone at the kiln entrance. This process, referred to as ‘internal recuperation’, relies on the flow control element which is part of the ecombustion concept.

Traditional heat recuperation systems require a more robust design, where all components are manufactured to be used at higher temperatures, resulting in a higher initial investment. NUTEC Bickley's ecombustion system uses air traveling back through the tunnel kiln interior, to be ignited when it mixes with fuel gas injected through the burners.

“ecombustion helps customers make significant cost savings, and they are seeing the many advantages of incorporating its power into their new projects,” added Alberto Cantú.

“It quickly justifies its adoption. Where gas prices are relatively low, then a payback period of around two years can be expected (depending on the application).”

“However, in the increasingly large number of areas around the world experiencing high gas tariffs, given typical consumption rates this payback period can be reduced to less than a year, sometimes even as quickly as six months.”