Agglomeration of Ash in Fluidized Beds Gasifying Coal: The Godel Phenomenon

Abstract

In a bed of anthracite or bituminous coke fluidized by air at 10 to 15 meters per second at 1200 degrees to 1400 degrees C, molten ash forms beads on the surface of a coke particle, some exuding from its interior. The beads merge and detach them-selves to grow further as loose fluidized ash agglomerates of low carbon content.

Destabilization of fluidized beds due to agglomeration part I: Theoretical model

“…Other examples of this type of fluidization are the Dorr-Oliver process to calcinate lime sludges and to roast Katanga ore and the Fuller cement process (Hovmand, 1978). A similar process of accreting fine ash particles in large solid agglomerates takes place in the ash agglomerating fluidized bed gasifiers and combustors described by Godel and Cosar (1967); Squires (1969Squires ( , 1972; Yerushalmi et al (1975) and Liss (1979).…”

The Physical Transformation of the Mineral Matter in Pulverized Coal Under Simulated Combustion Conditions

“…Although several investigators (Paulson and Ramsden, 1970;Ramsden , 1969;Yerushalmi et al, 1975;Lightman and Street, 1968;Street et al, 1969;Mitchell and Lee, 1962) have observed alggomeration of mineral matter in coal , little information is available on when during the combustion process the major part of the agglomeration occurs or how many agglomerates are produced per coal particle. Models of ash agglomeration will depend upon the manner in which the carbon surface burns.…”

Reactor Design and its Impact on Performance and Products

“…Such a problem has a critical effect on the overall conversion of the biomass material due to the formation of dead zones and, in extreme cases, complete de-fluidization. Agglomeration was first observed during coal gasification in a fluidized bed as reported by Yerushalmi et al [36] and Gluckman et al [37]. Since then, numerous publications have been published; however, very few have been specifically focused on agglomeration during biomass thermal conversion.…”