Characteristics of clinker formation in a circulating fluidized bed boiler firing Korean anthracite

Abstract

To shed light on the causes of clinker formation during the initial operation period of the Tonghae circulating fluidized bed (CFB) boiler, which uses Korean anthracite as fuel, the properties of ash, sand and limestone particles and the mixtures of each gradient have been characterized. The clinkers formed in the loopseals and the fluidized bed ash cooler (FBAC) of the CFB boiler were also characterized by analyzing the composition, the surface phenomena and the crystal structure of the clinkers. As a result, the black clinker was found to come from the sand particles and the composition of the white clinker was found to be similar to that of ash particles. The cause of the clinker formation in the FBAC proved that ash was sticking to molten or sintered phases in the high temperature regions in the boiler. On the other hand, the composition of the ash changed with the particle size, showing an enrichment of Fe 2 O 3 as the particle size decreased. Also, the ash particles between 75-100 µm contained more than 11% CaO which resulted in low initial deformation temperature of the particles. So it is possible to explain that the amount of Fe and Ca in the fine particles of the ash plays a crucial role in the formation of agglomerates in the CFB boiler.

Understanding mineral behaviors during anthracite fluidized-bed gasification based on slag characteristics

“…The amount of amorphous matter (the material which does not have its molecules arranged in a lattice, or crystalline structure) is crucial for the formation of ''sticky'' deposits in a practical gasification system. Ash particle agglomeration generally occurs when an amorphous phase is present to form a bond or when ashes adhere to molten or sintered phases in local high-temperature zones, potentially causing slag formation [32,33]. During coal gasification, the major factor for slag formation is adhesion of amorphous ferric silicate (Shenhua bitumite [34]) or sodium silicate (high-sodium lignite [35]) particles.…”

Agglomeration in Stripper Ash Coolers and Its Possible Remedial Solutions: a Case Study

“…Proper documentation of agglomeration in stripper ash cooler is rarely found in the literature [7]. Only few Authors have highlighted [7] the problem of clinker formation in stripper ash cooler fluidized bed unit.…”

“…Proper documentation of agglomeration in stripper ash cooler is rarely found in the literature [7]. Only few Authors have highlighted [7] the problem of clinker formation in stripper ash cooler fluidized bed unit. Few authors have studied the stripper ash cooler at lab scale [8,9] as well as industrial level [7,[10][11][12][13].…”

“…Only few Authors have highlighted [7] the problem of clinker formation in stripper ash cooler fluidized bed unit. Few authors have studied the stripper ash cooler at lab scale [8,9] as well as industrial level [7,[10][11][12][13]. Zhang et al [10] studied the fluidized bed ash cooler used in a CFB boiler.…”

“…They studied the flow behavior of ash in the unit. Park et al [7] studied the characteristics of clinker formation in a CFB boiler firing Korean anthracite. They found that the amount of Fe and Ca in the fine particles of the ash plays a crucial role in the formation of agglomerates in the CFB boiler.…”