Xiaofeng Lu

Industrial Application Study on New-Type Mixed-Flow Fluidized Bed Bottom Ash Cooler

As a key auxiliary device of CFB boiler, the bottom ash cooler (BAC) has a direct influence on secure and economic operation of the boiler. The operating situation of domestic CFB power plant is complex and changeable with a bad coal-fired condition. The principle for designing BAC suitable for the bad coal-fired condition and high parameter CFB boilers was summarized in this paper. Meanwhile, a new-type mixed-flow fluidized bed bottom ash cooler was successfully designed on the basis of the comprehensive investigation on the existing BAC s merits and drawbacks. Using coarse/fine slag separation technology and micro-bubbling fluidization are the significant characteristics of this new BAC. This paper also puts great emphasis on its industrial test in a 460t/h CFB boiler. The results indicate that it achieves significant separation of the coarse/fine slag, an obvious cooling effect, no slag block and coking phenomenon, and continuous stable operation. Figs 7, Tabs 4 and Refs 11.

Experimental Research on Gas-Solid Flow in a Square Cyclone Separator with Double Inlets

A square cyclone separator with double inlets was developed for a new type Circulating Fluidized Bed (CFB) boiler arrangement scheme including two furnaces. Experiments on the performance and gas-solid flow recorded by a high-speed photography have been conducted in a cold test rig with a separator cross section 400mm×400mm. Experimental results indicated that with the inlet velocity of 22.4m/s and the inlet solids concentration of 4.9g/m3, the cut size is 15 μm, the critical size is 75μm, and the pressure drop coefficient is 1.7. The performance is also affected by the inlet velocity and solids concentration. The trajectory of particles shows that the particles swirl in the region near the wall and are easily separated. Especially, the instantaneous separation occurred at the corner is very significant for the improvement of the collection efficiency with the high inlet solids concentration for CFB boiler.

Investigation on the Integrated External Heat Exchanger for a New Type CFB Boiler Arrangement

Various external heat exchangers (EHE) are widely used with large-scale CFB boiler. The solid mass flow rate diverted from the standpipe to the EHE or the loop seal can usually be controlled well and the flow of hot particles into the EHE passes through all heat exchanger chambers in succession. However, it is not feasible to control the quantity of heat transfer of different and multilevel heat transfer surfaces in the EHE. A new type of EHE in which the solid flow was controlled by pneumatic is developed in this paper. The major feature of this EHE system is that the solid flow can be introduced to one heat transfer chamber or another. Thereby the distribution of the quantity of heat transfer can be easily adjusted. Simultaneously, the EHE and recycle device were connected in order to recycle the solid back to the furnace steadily. Experiments completed in a visible cold EHE test rig showed that the solid mass flow rate to the EHE or the loop seal, to two heat transfer chambers, to two exports of solid could be controlled well by the aeration airflows into each chamber. In addition, the integrated EHE has been used in a new designed CFB boiler successfully.