ADDITIVES FOR THE REDUCTION OF ALKALI CHLORIDES DURING BIOMASS COMBUSTION: A REVIEW

Abstract

Introduction:
The number of steam generators that burn biomass for steam production is constantly growing. One of the problems they face is severe corrosion, a consequence of the content of alkali chlorides and other corrosive species that these biofuels contain.
Objective:
To carry out a bibliographic review on the use of additives to reduce the effects of the presence of alkali chlorides in biofuels used in steam generators.
Materials and Methods:
References were consulted from 1998 to 2023 related to the main alternatives for the mitigation of the effects of corrosion, caused by the presence in biomass (used in combustion for electricity generation) of a high concentration of alkaline chlorides, going deeper into the use of different types of additives or mixtures of them.
Results and Discussion:
Several of the reported methods have medium to high effectiveness in reducing corrosion and the complexity of their implementation. The main additives found are ammonium sulfate, based on aluminum and silicon, calcium and sulfur. The best effectiveness-complexity balance corresponds to the use of kaolin.
Conclusions:
Alkali chlorides increase the corrosion rate of materials used in steam superheaters. Reactions between the metal surface and these species, or others that contain alkalis must be avoided to reduce corrosion in them, for which additives capable of sequestering alkalis from the biomass can be used, forming less aggressive compounds.