Development of a novel fluidized bed ash cooler for circulating fluidized bed boilers: Experimental study and application

A novel bottom ash cooler (BAC) called compound fluidized bed ash cooler (CFBAC) was developed in this paper. The CFBAC combined the major technical features of spouted bed and bubbling bed, and could achieve the selective discharge on the bottom ash. Experiments about the gas–solid flow characteristics of the CFBAC were conducted in a visible cold test rig. The experimental results indicated that the separation chamber working in the spouted bed state had a good particle separation effect on the boiler bottom ash. A small quantity of fluidizing air was needed for the cooling chambers to work in the bubbling bed state. The particle separation effect could be controlled by the fluidizing air flow and physical dimensions such as the height of separation partition. The CFBAC had also been industrially applied in a 300 MW circulating fluidized bed unit. The application showed that the CFBAC had a well separation effect, an excellent adaptability on the bottom ash, a good cooling effect and a large ash discharge capacity over 30 t/h. Compared with the water-cooled BAC, the CFBAC had a better energy conservation performance.

Graphical abstractA novel bottom ash cooler named compound fluidized bed ash cooler (CFBAC) was developed. It combined the major technical features of spouted bed and bubbling bed, and could achieve the selective ash discharge. According to the experimental results, the CFBAC had been industrially applied in a 300 MW circulating fluidized bed unit.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► A novel bottom ash cooler could achieve selective ash discharge was developed. ► Combined the major features of spouted bed and bubbling bed. ► Separation chamber working in spouted bed had a good particle separation effect. ► The separation effect controlled by the fluidizing air flow and physical dimensions. ► The new FBAC had been successfully applied in a 300 MWe CFB unit.