Transient Cold Flow Simulation of Fast-Fluidized Bed Air Reactor with Hematite as an Oxygen Carrier for Chemical Looping Combustion

Chemical looping combustion (CLC) is the most reliable carbon capture technology for curtailing CO2 insertion into the atmosphere. This paper presents the cold flow simulation results necessary to understand the hydrodynamic viability of the fast-fluidized bed air reactor. Hematite is selected as an oxygen carrier due to its easy availability and active nature during the reactions. The dense discrete phase model (DDPM) approach using the commercial software Ansys Fluent is applied in the simulation. An accurate and stable solution is achieved using the second-order upwind numerical scheme. A pressure difference of 150 kPa is obtained between the outlet and inlet of the selected air reactor, which is necessary for the movement of the particle. The stable circulating rate of hematite is achieved after 28 s of particle injection inside the air reactor. The results have been validated from the experimental results taken from the literature

CFD simulation of steady state heat transfer in bubble columns

A low Reynolds number k-ε computational fluid dynamics (CFD) model has been used for the description of flow pattern near the wall. An excellent agreement has been shown between the predicted and experimental hold-up and velocity profiles. The CFD model has been extended for the prediction of heat transfer for two-phase gas-liquid flows in bubble columns. A comparison has been presented between the predicted and the experimental data

Separation Characteristics of Liquid– Liquid Dispersions: Gravity and Centrifugal Settlers

The separation efficiency/capacity of a large number of liquid–liquid dispersions has been investigated over a wide range of physical properties: 100 < Δρ < 625 kg/m³, 3 < σ < 58.3 mN/m, 0.3 < μ_C and μ_D < 12.2 mPa·s. For gravity separation, phase disengagement experiments were performed in a 100 mL measuring cylinder. The centrifugal separation was carried out in different sizes of annular centrifugal extractors (ACE) with rotor sizes ranging from 30 to 250 mm over a rotor speed of 6.28 rad/s < <i>N</i> < 314.15 rad/s. The rotor speed translated into power consumption over the range of 20–600 kW/m³. A novel data driven correlation containing physical properties and separation forces has been developed using Random Forest technique for dispersion number. The developed correlation could be used for the design of gravity or centrifugal separators