Hot section corrosion

Generally, hot section corrosion refers to corrosion of the furnace tubes, superheater or any boiler section where temperatures above 1000°F may be encountered. At temperatures above 1000°F many of the fuel ash constituents are molten. This molten ash can severely attack the boiler metal surface through a fluxing action.

The fluxing action of ash dissolves the protective metal oxide film, exposing fresh metal to further attack.

Molten deposits may also fuse into the metal surfaces, distorting the lattice of the metal and leading to its eventual failure.

To prevent hot section corrosion molten ash must he eliminated. This can be accomplished through the steps mentioned under the section discussing deposits.

The two approaches would be to use a slag modifier and/or reduce excess air.