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Every technician managing a unit knows the phenomena listed below, which have a significant effect on the functionality of the internal lining of the unit. We decided to describe them professionally, and thereby point out their pitfalls for the operation of the unit.
Bursting occurs during the operation of the unit, when the lining is chemically or mechanically stressed, and when, due to the penetration (especially diffusion) of flue gases into the lining, usually through open pores, a reaction occurs between the flue gas components and the lining material itself.
This produces compounds in or on the lining that have different chemical compositions and physical parameters than the lining or combustion medium itself. These new compounds cause inhomogeneities in the lining structure, and the above-mentioned phenomena occur due to a different bulk density. Therefore, they also occupy different volumes.
Bursting often leads to the very rapid destruction of linings, and subsequently to costly repairs. It is very prudent if the material is selected with thoroughness and high expertise that can delay and alleviate such bursting to some extent. The project designers therefore respond to the operating conditions of the unit, the charge, and the service life. Equally important is the lining assembly technology used.
The following may occur:
Alkali-bursting - is caused by reactions of alkaline (basic) components of flue gases. There are usually flaking and cracks in the lining. This happens mainly during the combustion of biomasses, which are often contaminated and, in addition to their own composition, retain residual amounts of fertilizers and crop care products.
Silicate-bursting - is a similar phenomenon, which is caused by flue gases containing silica, such as dust from the charge during the production of glass.
In this case, mainly alkaline linings are attacked - e.g. magnesite fittings.
Disruption of fittings by flue gases, vapours, or slag containing components rich in iron oxides. This is, for example, the disruption of bonds in chrome-magnesite fittings; often there is also a rupture of joints in the lining.
Author: Ing. Vojtěch Kavan
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