Kamath, Satish

Gas-liquid-solid reactive flows using stochastic Euler-Lagrangian techniques

 

Introduction

Bubble column reactors are very widely used gas liquid contactors in the chemical and energy industries. Wide variety of processes like absorption, fermentation, Fischer-Tropsch synthesis, waste water treatment, bio-reactors etc. are carried out through bubble columns. Design of such columns are based on different parameters like throughput, conversion, type of reactions etc. The industrial grade columns with large throughputs are 100-300 m3. Larger columns are also employed for bio-processes like fermentation (3000 m3) and also waste water treatment (20000 m3).

The flow within a column is quite complex as it is driven by the ascending bubbles. It directly has an effect on the heat and mass transfer taking place within the column which controls the efficiency of the whole process. Therefore the problem is divided into different scales to simulate all the transport phenomena accurately.

The purpose of this project is to simulate industrial scale slurry bubble columns using stochastic Euler-Lagrangian methods. The method that is currently employed is Euler-Euler approach using multi fluid models to simulate bubble columns at this scale which treats bubbles as a continuous gas phase. The liquid and gas phase coupling is achieved through closures obtained from more detailed simulations at smaller scales (direct numerical and discrete bubble simulations).

Therefore this (stochastic Euler-Lagrange) method is being developed that treats bubbles as discrete phases at this scale with same/lesser computational costs as that of the Euler-Euler approaches.