Novel helical screw-fluidized bed reactor for bio-oil production in slow-pyrolysis mode: A preliminary study

Slow pyrolysis has been generally recognized as an improper mode of bio-oil production because it produces a low liquid yield of 30 wt.%. This research introduces a type of innovation in which the designed helical screw fluidized bed reactor can operate in the slow-pyrolysis mode to obtain high-yielding liquids. The concept of the reactor was designed to develop the fluidization condition by using a mechanical device. Experiments were performed at the heating rate of 10 degrees C/min to achieve 500 degrees C without using any inert gases. The focus of the preliminary study was on reactor performance, particularly for a setting with helical rotation (50 rpm) and another one without rotation (0 rpm). For the setting without the influence of helical screw rotation, the obtained liquid yield was 38.4 wt.%. Then, the liquid yield was remarkably increased to 51.6 wt.% when the 50 rpm condition was applied. The liquid obtained from the 50-rpm condition contained a higher proportion of organic phase than aqueous phase. The presence of oxygen compound in the organic phase in the 50-rpm condition was lower than that in the 0-rpm condition. Apart from the ability to obtain high-yielding liquids in the slow-pyrolysis condition, the reactor also has other good features, such as low pyrolysis time, fast vapor production, non-agglomeration of particles, non-occurrence of pressure drop during process implementation, and production of good-quality byproduct char.