Computational Analysis of the Hydrodynamic Behavior for Different Air Distributor Designs of Fluidized Bed Gasifier

Abstract

Fluidized bed gasification has proven to be an appropriate technique for converting various biomass feedstocks into helpful energy. Air distributor plate design is one of the critical factors affecting the thermochemical conversion performance of fluidized bed gasifiers. The present study is proposed to investigate the mixing pattern and pressure drop across different configurations of air distributors using a two-fluid model (TFM) of finite volume method-based solver ANSYS FLUENT. The pressure drop across the bed and mixing pattern have been investigated through qualitative and quantitative analysis of CFD results using three diverse distributor plate designs: perforated plate, 90° slotted plate, and 45° swirling slotted plate. The pressure drop by employing the perforated distributor plate reveals the highest pressure drop due to the smallest open area ratio. However, the pressure drop in the case of 90° slotted plate is found to be 7% and 4% lesser than perforated and 45° slotted plate respectively due to a smaller velocity head developed through the wider open area of the straight slotted plates. The distributor design configuration having a 45° slotted plate exhibits considerable pressure drop compared to the 90° slotted plate due to the longer path length of the slot. Numerical pressure drop results across the bed with different types of distributor plates prove reasonable agreement with the experimental results available in the literature. Mixing behavior in perforated distributor plates exhibits lower portion solid volume fraction of around 0.58. However, it falls rapidly as go up the riser (7.7% of column height); 90° slotted plate shows bottom region solid volume fraction of around 0.5. In addition, it exhibits an even broader range of sand volume fraction and column height (13.46% of column height). Finally, the 45° distributor plate reveals the highest range of volume fraction through the riser height (17.3% of column height), indicating the better mixing characteristics of the fluidized zone.

Optimizing Design and Operational Parameters for Enhanced Mixing and Hydrodynamics in Bubbling Fluidized Bed Gasifiers: An Experimental and CFD-Based Approach

“…A wider open area in a straight-slotted plate developed a smaller velocity head. The distributor 45 • slotted plate exhibited a higher pressure drop than the 90 • slotted plate due to the longer path length of the slots [29]. In a fluidized bed gasifier, to check the hydrodynamics of gas-solid mixtures and particles-gas and particleparticle contact mechanisms, four different perforated plate distributors with rectangular and triangular arrangements with different holes and pitches were studied.…”

Influence on the fluidization pattern of a freely bubbling fluidized bed with different modes of air supply

“…For instance, the use of a distributor plate increases the auxiliary power consumption required to pump the gas through the reactor. Additionally, the distributor plate has to be selected depending on the reactor types and process as the distributor plays a critical role in the reactor performance (Raza et al, 2021). In addition, there are challenges in operating the reactor with the distributor plate, which requires cleaning and maintenance due to clogging of the pores of the distributor plate by the fine particles and sintering.…”

Proceedings of the 63rd International Conference of Scandinavian Simulation Society, SIMS 2022, Trondheim, Norway, September 20-21, 2022

“…Additionally, the distributor plate has to be selected depending on the reactor types and process as the distributor plays a critical role in the reactor performance (Raza et al, 2021). In addition, there are challenges in operating the reactor with the distributor plate, which requires cleaning and maintenance due to clogging of the pores of the distributor plate by the fine particles and sintering.…”