Recovery Boiler Corrosion
This article is a part of the book Kraft Recovery Boilers. A little undertandig of my study. I won't put in this article therms of chemistry. The objective is just to start a conversation about this theme.
In a industrial company of cellulose, the Kraft recovery boiler is the heart of the production, and the well being of it is the main focus of operators and maintence team. (Honghi Tran, 1997) says controlling corrosion and maintaing tube integrity in recovery boilers is a major challenge for corrosion engineers. Corrosion has been found in all parts of the boiler, from the lower furnace throuth to the upper section and the electrostatic precipitator. Figure 1 . Locations where corrosion is found in recovery boilers. (Kraft Recovery Boilers, Terry N. Adams et all, 1997). The author continues, the corrosion can occurs in various forns, including sulfidation, thermal oxidation, strees corrosion cracking, molten salt corrosion, pitting corrosion and dew point corrosion.
Recovery boiler tubes corrode by reacting with compounds in flue gases and/or deposits to form a non-protective scale. For this reason, it is importante to understand the chemistry of flue gases and deposits, especially the type and the concetration of corrosive agents at the tube surface.
Elemental Sulfur Vapor: Elemental sulfur vapor causes severe tube damage by directly forming metal sulfide with the tube material, it may also react with the smel to form corrosive polysulfides, wich turn may attack the metal. Any conditions wich produce elemental sulfur will result in a high corrosion rate. In recovery boilers, such conditions may include:
