Comparative Study on Extracting Alumina from Circulating Fluidized-Bed and Pulverized-Coal Fly Ashes through Salt Activation

2013 ◽  
Vol 27 (12) ◽  
pp. 7868-7875 ◽  
Author(s):  
Chunbin Guo ◽  
Jingjing Zou ◽  
Cundi Wei ◽  
Yinshan Jiang
Keyword(s):  
Comparative Study ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pulverized Coal ◽  
Fly Ashes ◽  
Salt Activation ◽  
Coal Fly Ashes

Retrofitting 25T/h Pulverized Coal-Fired Boiler Into 35T/h Circulating Fluidized Bed Boiler for Burning Mixture of Coal and Bagasse

2005 ◽  
Author(s):  
Han-Ping Chen ◽  
Xian-Hua Wang ◽  
Shi-Hong Zhang ◽  
De-Chang Liu ◽  
Yu-Hua Lai ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Efficiency ◽  
Economic Benefits ◽  
Pulverized Coal ◽  
Industrial Wastes ◽  
Pollutant Emission ◽  
Fluidized Bed Combustion ◽  
Circulating Fluidized Bed Boiler ◽  
Combustion Technology

In China, there are a large number of pulverized coal-fired industrial boilers, whose steam capacities are usually relatively small. These boilers can burn only high-grade coal and have low combustion efficiency. Furthermore, the combustion emissions, such as SO2 and NOx, pollute the environment severely. Therefore it is very important and urgent to adopt economically efficient and environmentally friendly technologies to retrofit these boilers. At the same time, there are many industrial wastes, such as bagasse, wood waste, rubbish, petroleum coke and so on, need burning disposal in China. Fluidized bed combustion technology is a kind of clear combustion technology, which has many advantages, such as excellence fuel flexibility, high combustion efficiency, low pollutant emission and good turndown capability etc. So, adopting fluidized bed combustion technology, retrofitting pulverized coal-fired boiler into fluidized bed boiler can realize pure burning various wastes or co-firing with coal, which should have great economic benefits and social benefits. And the application prospect of the method is also extensive. The State Key Laboratory of Coal Combustion has successfully retrofitted a 25t/h pulverized coal-fired boiler into circulating fluidized bed boiler with in-bed tubes and downward exhaust cyclone. The retrofitted boiler can burn mixture of coal and bagasse and the steam capacity reaches 35t/h. This paper presents the retrofitting measures and the operation status of the boiler after retrofitting.

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.

Experimental Study of CFB Modification Fly Ash in Concrete

2014 ◽  
Vol 1051 ◽  
pp. 743-747 ◽  
Author(s):  
Rong Jin Xu ◽  
Yan Kai Huo ◽  
Bin Teng ◽  
Si Hai Song
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Carbon Content ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pulverized Coal ◽  
Experimental Results ◽  
Unburned Carbon ◽  
Fluidized Bed Combustion ◽  
Effective Use

The character of the Fly ash of Circulating Fluidized Bed Boiler (CFB Fly ash) is greatly different from that of Pulverized coal furnace for its high unburned carbon. In order to make effective use of CFB Fly ash in concrete, carbon content was decreased by simulated fluidized bed combustion in laboratory and a series of concerned experiments were carried out on CFB Fly ash. The experimental results indicate that CFB modification Fly ash is possible to be used in concrete to partially replaced cement. It is a valuable reference for CFB Fly ash technical engineers.

A New Concept for Operation of a Pulverized Coal Fired Boiler Using Circulating Fluidized Bed Firing

1989 ◽  
Vol 111 (4) ◽  
pp. 626-630 ◽  
Author(s):  
P. Basu ◽  
P. K. Halder
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pulverized Coal ◽  
Life Extension ◽  
Heat Absorption ◽  
Pulverized Coal Boiler ◽  
Fuel Flexibility ◽  
Thermal Calculations ◽  
Coal Washery ◽  
Coal Boiler

The feasibility of adapting existing pulverized coal fired boilers slated for life extension to circulating fluidized bed firing is examined by considering the case of a 150 MWe tangentially fired pulverized coal boiler. The proposed modifications call for a minimum of change in existing units. Thermal calculations are presented to show how heat absorption in different sections of the converted boiler can be matched to that in the pre-existing pulverized coal fired boiler. Data for two load conditions are presented to identify problems associated with low loads. Fuel flexibility in the converted circulating fluidized bed unit is shown by repeating the thermal calculations for coal washery rejects. It is concluded that the adoption of circulating fluidized bed firing is thermodynamically feasible.

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