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The solid particle flow characteristics inside the cone valve were experimentally and numerically studied. The experiments were conducted at different valve sizes, valve opening positions, pressure drops, and fluidization velocities. Numerical simulation using the computational particle fluid dynamic method was also carried out over broader conditions. It is found that the solid particle flow inside the cone valve demonstrated the three-stage phenomena as the solid particle flew passing through two in-series connected orifice systems. The explanation of the three-stage phenomena of the solid particle flow rate to the valve opening was given according to the double-orifice flow model. Based on the physical nature of the solid particle flow characteristics, a semi-empirical model of the solid particle flow rate inside the cone valve was proposed. The model parameters, such as the saturated solid flow rate, the saturated valve opening, were determined using the experimental data and the existing knowledge of orifice systems. The model was then verified using the experimental data and presented acceptable prediction accuracy.

The bottom ash cooler is an important auxiliary equipment of a circulating fluidized bed (CFB) boiler. As the CFB boiler technology develops, the rotary ash coolers have partially substituted the fluidized bed bottom ash coolers in the industrial practice due to its excellent reliability. To meet the increased output requirement, a double-cylinder rotary ash cooler, rather than the conventional single-cylinder one, was proposed in the present study. This paper provided the design of the double-cylinder rotary ash cooler and presented its application in a 300 MWe CFB boiler. The design parameters, structural features, heat transfer performance, as well as the field trial results were discussed in the present study. In addition, a semi-empirical model was proposed to provide theoretical support for the design principle of the double-cylinder rotary ash cooler. The field trial results showed that the actual output of the installed double-cylinder rotary ash cooler was up to 32 t/h with the ash temperature at the outlet being the designed value, much greater than the value (~23 t/h) of the single-cylinder one at approximately the same size. Particularly, this novel bottom ash cooler had run continuously for more than three years without any maintenances due to its reasonable design.