Brick Liners Maintenance

Many structures built in the 1970s through the mid-1980s were equipped with free-standing, acid-resistant brick linings. Although some of these independent brick-lined chimneys operate dry and encounter minimal problems, many work downstream of old-generation wet FGD systems still using bypassed flue gas for reheat.

Brick Liners Maintenance
Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: April 1, 2007

By Kenny Kendall
Many structures built in the 1970s through the mid-1980s were equipped with free-standing, acid-resistant brick linings. Although some of these independent brick-lined chimneys operate dry and encounter minimal problems, many work downstream of old-generation wet FGD systems still using bypassed flue gas for reheat.
At its inception, the acid-resistant brick liner was touted as the answer to one of this type of chimney's biggest maintenance problems – liners made from carbon steel that were quickly damaged by the harsh acidic environment found downstream of the wet scrubbers.
Unfortunately, though, the new brick liners were not a panacea. After two or three decades of service, the majority of these liners have developed a lean or deflected position as a result of operating wet. Studies indicate that numerous complex factors can influence this deflection, but there is very rarely a common contributor.
Liner lean
Only two common factors were identified in all leaning liner cases: the use of bypass gas for reheat and the application of red shale brick in the liner construction. Other varied factors that can influence liner lean include the quantity and composition of moisture deposited on the liner impingement area, composition of the coal used, flue gas reheat methods, and fluctuating flue gas temperatures.
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