scholarly journals Process Kinetics of the Carbonation of Fly Ashes: A Research Study

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 253
Author(s):  
Marian Jacek Łączny ◽  
Sebastian Iwaszenko ◽  
Adam Smoliński
Keyword(s):  
Fluidized Bed ◽  
Power Plants ◽  
Cement Industry ◽  
Free Calcium ◽  
Fluidized Bed Combustion ◽  
Drying Process ◽  
Fly Ashes ◽  
Process Kinetics ◽  
Concrete Production ◽  
Kinetics Of

The aim of the paper is to present the results of research on the carbonation process kinetics of coal combustion ashes originating from fluidized bed boilers used in power plants. Based on the thermogravimetric analysis (TGA), the hypothesis that carbon dioxide is bounded by the mineral substances (calcium compounds) in the fly ashes was confirmed. Determining the kinetic parameters of the carbonation of fly ashes requires simultaneously taking into consideration the kinetics of the drying process of the sample. The drying process of the sample masks the effect of the reaction of CO2 with calcium compound. Unlike the ashes generated in pulverized fuel boilers, fly ashes contain irregular amorphic mineral components or poorly crystalized products of complete or partial dehydroxylation of claystone substance present in shale formations constituting the gangue as well as anhydrite (CaSO4), a desulfurization product. The content of free calcium oxide (CaO) in such ashes ranges from a few to several percent, which is a significant obstacle considering their use in cement and concrete production as type II admixtures understood to be inorganic grained materials of pozzolanic or latent hydraulic properties. The paper presents effective mechanisms which reduce the content of free CaO in ashes from Fluidized Bed Combustion (FBC) boilers to a level that allows their commercial utilization in the cement industry.

Reactivation Studies on Six Fly Ashes From Commercial CFB Boilers

2005 ◽  
Author(s):  
Y. Wu ◽  
J.-P. Charland ◽  
E. J. Anthony ◽  
L. Jia
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Liquid Water ◽  
Circulating Fluidized Bed ◽  
Absorption Capacity ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Commercial Scale ◽  
Circulating Fluidized Bed Combustion ◽  
So2 Absorption

Six different fly ashes from commercial-scale circulating fluidized bed combustion (CFBC) boilers and the carbon-free residues of these ashes were hydrated with liquid water or steam to determine whether hydration could improve sorbent utilization in these samples under fluidized bed combustion conditions. After hydration, for two fly ashes (FA1 and FA6) and three carbon-free samples (FA2-A, FA3-A and FA6-A), the capacity for taking up SO2 showed limited or medium improvement; however, hydration was evidently ineffective in reactivating the remaining samples. It is believed that the reason samples FA6 and FA6-A show a relatively high improvement in SO2 absorption capacity is that these ashes had a larger particle size than any of the other fly ashes examined here. In general, even for these “reactivatable” fly ashes, reactivation by hydration with either liquid water or steam appeared far less promising than for bed ashes, which have been shown to exhibit significant improvement in sulphur capture during re-sulphation. Hydration, whether by steam or liquid water, is not recommended for fly ash, which has a very limited residence time in the boiler due to its small particle size and instead this paper recommends alternative strategies.

scholarly journals Enrichment of thallium in fly ashes in a Spanish circulating fluidized-bed combustion plant

Fuel ◽  
2015 ◽  
Vol 146 ◽  
pp. 51-55 ◽  
Author(s):  
M. Antonia López-Antón ◽  
D. Alan Spears ◽  
Mercedes Díaz-Somoano ◽  
Luis Diaz ◽  
M. Rosa Martínez-Tarazona
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Circulating Fluidized Bed Combustion

scholarly journals Alkali Activation–Granulation of Hazardous Fluidized Bed Combustion Fly Ashes

2016 ◽  
Vol 8 (2) ◽  
pp. 339-348 ◽  
Author(s):  
Juho Yliniemi ◽  
Janne Pesonen ◽  
Pekka Tanskanen ◽  
Olli Peltosaari ◽  
Minna Tiainen ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Alkali Activation ◽  
Fluidized Bed Combustion ◽  
Fly Ashes

Study on the Utilization of FBC Ashes as Cement Admixture

2011 ◽  
Vol 99-100 ◽  
pp. 116-119
Author(s):  
Jing Xiang Liu ◽  
Yuan Ming Song ◽  
Hui Zhong Xu ◽  
Yu Long Ma ◽  
Yu Bo Yue ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Fluidized Bed ◽  
Coal Combustion ◽  
Cement Mortar ◽  
Setting Time ◽  
Pulverized Coal Combustion ◽  
Fluidized Bed Combustion ◽  
Fly Ashes ◽  
Cement System

Compared with ordinary Pulverized Coal Combustion (PC) fly ashes, Fluidized Bed Combustion (FBC) ashes have some special properties. The effect of FBC ashes content on the strength of cement mortar was studied, and the physical properties of FBC ashes-cement mortar with 30% FBC ashes were also investigated. The results show that the flexural and compressive strength at 7 and 28 days of the mortar gradually decreases with the increase of FBC ashes content. Under the same dosage, the strength of FBC ashes-cement mortar is greater than that of PC fly ashes-cement mortar. The FBC ashes-cement system presents a normal setting time but poor soundness with more than 3.5% SO3. This work confirms that the properties of FBC ashes-cement system are superior to those of PC fly ashes-cement system when SO3 content is no more than 3.5%.

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