Furnaces molten salts corrosion

In water-wall incinerators. The internal walls of the combustion chamber are lined with boiler tubes that are arranged vertically and welded together in continuous sections. When water walls are employed in place of refrac toiy materials, they are not only useful for the recovery of steam but also extremely effective in controlling furnace temperature without introducing excess air however, they are subject to corrosion by the hydrochloric acid produced from the burning of some plastic compounds and the molten ash containing salts (chlorides and sulfates) that attach to the tubes. 

Unlike most other salts, measurement of mixing enthalpies of molten alkali metal carbonates, due to their corrosive nature, cannot be performed in fused silica containers and be mixed by the usual break-off technique. Andersen and Kleppa (1976) showed that the Au20Pd alloy was corroded only negligibly by alkali metal carbonate melts kept under a relatively high CO2 pressure. The experimental arrangement included plunger as well as a dipper crucible that could be manipulated from the outer side of the furnace. The mass loss of the most volatile carbonate, Rb2C03, was about 0.3%. However, in spite of the relatively small vaporization losses, the attack of vapors on the fused silica liner was considerable and the lower part of the device had to be discarded after 10-15 experiments. 

---