关键词:

高通量输送, 双流化床气化, 颗粒循环量, 循环流化床

Abstract:

Gasification in a combination of dual fluidized bed and high-density transport bed is becoming attractive for coal and biomass conversions.In order to achieve high conversion efficiency both technologies require a pneumatic riser（i.e.，transport bed）with high particle flux as well as high bed density.The present paper investigated how to build and control high solids flux and its accompanying bed density in a newly configured flow cycle based on circulating fluidized bed（CFB）.Coupling a moving bed to the bottom section of the CFB riser was proposed to increase the driving pressure for the riser and in turn to increase the particle holdup inside the riser bottom and also to increase the solids circulation rate in the entire cycle.Experiments in a 90 mm i.d.bed constructed according to the idea showed that solids circulation rate and particle holdup in the riser were highly dependent on the running status of the moving bed.Solids circulation rate higher than 400 kg•m^-2•s^-1 was realized at superficial gas（air）velocity of about 9.6 m•s^-1，and this circulation rate was accompanied with an evidently-dense flow in the riser bottom.The corresponding mass ratio of solids flux to gas flux was close to 40，a value much higher than that in usual CFBs.The paper investigated also the influences of secondary air flow and solids inventory on solids circulation rate and the dense flow region present in the transport bed bottom.

Key words:

高通量输送, 双流化床气化, 颗粒循环量, 循环流化床