The attrition behavior of an Italian limestone during a) first sulphation and b) re-sulphation after water reactivation was investigated in a bench scale bubbling fluidized bed. Operating conditions of the bed were those typical of atmospheric bubbling fluidized bed combustion. Three different particle size ranges of the limestone were investigated. Batchwise experiments were carried out in order to study the influence of the chemical reactions and of the reactivation step on the parallel particle fragmentation and abrasion in the bed. Reactivation was accomplished by immersion of the spent sorbent in water under controlled conditions until all unreacted CaO in the particles was converted to Ca(OH)2. Particle-size distribution changes and generated fines elutriation rates from the bed were followed throughout conversion during each step. Flue gas SO2 concentration was followed continuously in order to assess calcium conversion degree as a function of time during both first sulphation and re-sulphation. SEM-EDX analysis was carried out on polished cross-section of a) sulphated, b) hydrated and c) re-sulphated limestone particles in order to follow the changes of both particle morphology and distribution of species within the particle during the different stages of the process. Results indicated that water reactivation was effective in approximately doubling the final conversion degree of the limestone upon further re-injection of the particles in the bed for all the three size ranges investigated. On the other hand the reactivation process did not promote any significant enhancement of the limestone attrition. Analysis of SEM-EDX micrographs was useful to investigate the changes of the particle structure after each step and to relate the attrition behavior of the limestone to the particle morphology. It also revealed a marked redistribution of sulphur in the particles upon hydration, that could lead to further access to unconverted calcium oxide during the re-sulphation step.
The effect of limestone reactivation on the attrition behavior during fluidized bed desulphurization / Scala, Fabrizio; Montagnaro, Fabio; Salatino, Piero. - STAMPA. - (2001), pp. 69-1-69-7. (Intervento presentato al convegno 16th International Conference on Fluidized Bed Combustion tenutosi a Reno, Nevada, USA nel 13-16 Maggio).
The effect of limestone reactivation on the attrition behavior during fluidized bed desulphurization
SCALA, FABRIZIO;MONTAGNARO, FABIO;SALATINO, PIERO
2001
Abstract
The attrition behavior of an Italian limestone during a) first sulphation and b) re-sulphation after water reactivation was investigated in a bench scale bubbling fluidized bed. Operating conditions of the bed were those typical of atmospheric bubbling fluidized bed combustion. Three different particle size ranges of the limestone were investigated. Batchwise experiments were carried out in order to study the influence of the chemical reactions and of the reactivation step on the parallel particle fragmentation and abrasion in the bed. Reactivation was accomplished by immersion of the spent sorbent in water under controlled conditions until all unreacted CaO in the particles was converted to Ca(OH)2. Particle-size distribution changes and generated fines elutriation rates from the bed were followed throughout conversion during each step. Flue gas SO2 concentration was followed continuously in order to assess calcium conversion degree as a function of time during both first sulphation and re-sulphation. SEM-EDX analysis was carried out on polished cross-section of a) sulphated, b) hydrated and c) re-sulphated limestone particles in order to follow the changes of both particle morphology and distribution of species within the particle during the different stages of the process. Results indicated that water reactivation was effective in approximately doubling the final conversion degree of the limestone upon further re-injection of the particles in the bed for all the three size ranges investigated. On the other hand the reactivation process did not promote any significant enhancement of the limestone attrition. Analysis of SEM-EDX micrographs was useful to investigate the changes of the particle structure after each step and to relate the attrition behavior of the limestone to the particle morphology. It also revealed a marked redistribution of sulphur in the particles upon hydration, that could lead to further access to unconverted calcium oxide during the re-sulphation step.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
