Design and Development of Bubbling Fluidized Bed Gasifier for Non-Woody Biomass Gasification

Bubbling fluidized bed (BFB) reactor is advantageous for synthesis gas or syngas production among other available gasifiers. In this study, a BFB gasifier has been designed, utilizing non-woody biomass (rice straw) and air as gasifying medium, to investigate the effect of equivalence ratio (ER), static bed height, and operating temperature on synthesis gas yield and gasification efficiency. To calculate various structural and operating parameters, a reaction chamber with a diameter of 10 cm and a bed material of 400-500 μm has been studied. Considering the minimum fluidization velocity, slugging velocity, and terminal velocity, the optimum operating velocity has been taken as 17.25 cm/s. The calculated optimum transport disengagement height (TDH) is 86 cm, and the freeboard height is approximately 116 cm. Thus, the overall height of the reactor has come up as 202 cm. Almost 80% carbon conversion efficiency (CCE) was achieved from this BFB reactor with an optimum ER value of 0.35 during rice straw gasification. The same gasifier results in a synthesis gas yield of 3.6 Nm³/kg with a lower heating value (LHV) of about 3.5 MJ/Nm³at optimum ER value. Further scaling up this process based on the findings of this study for industrial-scale synthesis gas production can pave a way for bioenergy generation from non-woody biomass.