Adsorption of Volatile Organic Compounds with Multistage Fluidized Bed

Volatile Organic Compounds (VOC) are the most common air pollutants emitted from different industrial process. A multistage fluidized bed adsorption/desorption process coupled with catalytic oxidization was proposed for VOC emission control. The experimental and modeling study for VOC adsorption/desorption process in multistage fluidized bed was carried out. A 20000 m³/h capacity system for VOC control was also constructed and successful demonstrated.

The influence of bed height on the VOC adsorption process in one stage fluidized bed is investigated with different gas velocity and solid flow rate. The increase of bed height results in the increase of gas phase efficiency and VOCs removal efficiency. When the bed height is 50 mm, the gas phase stage efficiency and VOCs removal efficiency reaches the highest value of 85% and 79% respectively.

The effects of gas velocity, gas/solid ratio and total stage number on the performance of multistage fluidized bed adsorption/desorption process have also been tested. The results show that the gas phase stage efficiency is decreasing with the stage from top to bottom. The stage efficiency and VOC removal efficiency are increasing with the decrease of gas-solid ratio. For the desorption process, the VOC concentration in the concentrated stream is more than ten times higher than that of adsorption stream and that is suitable for the following catalytic oxidation process.

The equilibrium model for multistage fluidized bed was established to describe the VOC adsorption/desorption process. The simulated result shows good agreement with the experimental results. The model is used in the design and operation of the industrial demonstration project.