Boiler Wall Protection With Rear Ventilated Refractory Tiles

The prevention of corrosion on boiler tube-walls has been a most difficult and cost intensive problem in WTE plants. This is specifically the case where the incineration boilers are operating with increased saturated steam temperatures and their corresponding pressures. In addition, variations in the garbage mixtures, with differing values of chemical content and varying waste composition give importance to the prevention of boiler tube corrosion. Several refractory lining systems and types have been installed over the previous 80 years and can be compared. In the early stages it began with simple concrete installations and only later was it developed to use heat resistant ceramic products, now essentially silicon carbide. 20 years ago cement or chemically bonded SiC monolithics (gunning, trowelling or casting materials) were usually installed to protect boiler walls, but today fabricated and fired SiC tiles, with their enhanced properties, are mainly used. A distinction is made between hanging and bolted tiles, as well as between oxide bonded and nitride bonded SiC material and between mortared, backfilled and rear ventilated tiles. All these systems were carefully examined and assessed. It proved possible to develop a revolutionary heat conduction and corrosion protection system utilising air. An air gap between the refractory SiC tiles and the boiler wall proved to be both simple and successful. By means of detailed and systematic documentation and monitoring, including J + G’ s “Air” tiling system, it has, for a few years, been possible to offer and recommend long lasting refractory linings with the aim of protecting boiler walls against corrosion, reducing operating costs and using the energy of the waste in an optimum manner.