CFD and statistical approach to optimize the average air velocity and air volume fraction in an inert-particles spouted-bed reactor (IPSBR) system

Abstract

Inert-particles spouted bed reactor (IPSBR) is characterized by intense mixing generated by the circular motion of the inert particles. The operating parameters play an important role in the performance of the IPSBR system, and therefore, parameter optimization is critical for the design and scale-up of this gas–liquid contact system. Computational fluid dynamics (CFD) provides detailed modeling of the system hydrodynamics, enabling the determination of the operating conditions that optimize the performance of this contact system. The present work optimizes the main IPSBR operating parameters, which include a feed-gas velocity in the range 0.5–1.5 m/s, orifice diameter in the range 0.001–0.005 m, gas head in the range 0.15–0.35 m, mixing-particle diameter in the range 0.009–0.0225 m, and mixing-particle to reactor volume fraction in the range 2.0–10.0 vol % (which represents 0.01–0.1 kg of mixing particles loading). The effects of these parameters on the average air velocity and average air volume fraction in the upper, middle, and conical regions of the reactor were studied. The specific distance for each region has been measured from the orifice point to be 50 mm for the conical region, 350 mm for the middle region and 550 mm for the upper rejoin. The selected factors were optimized to obtain the minimum air velocity distribution (maximum gas residence time) and the maximum air volume fraction (maximum interfacial area concentration) because these conditions will increase the gas holdup, the gas–liquid contact area, and the mass transfer coefficient among phases. Response surface methodology (RSM) was used to determine the optimum operating conditions. The regression analysis showed an excellent fit of the experimental data to a second-order polynomial model. The interaction between the process variables was evaluated using the obtained three-dimensional surface plots. The analysis revealed that under the optimized parameters of a feed-gas velocity of 1.5 m/s, orifice diameter of 0.001 m, gas head of 0.164 m, mixing-particle diameter of 0.0225 m, and mixing-particle loading of 0.02 kg, the minimum average air velocity and highest air volume fraction were observed throughout the reactor.

KOH-Based Modified Solvay Process for Removing Na Ions from High Salinity Reject Brine at High Temperatures

“…This observation confirms the effect of gas flowrate on CO 2 uptake, where a low gas flowrate resulted in a high residence time and hence high CO 2 capture [4,8]. This result reflects the novelty of the IPSBR [18][19][20], which can still operate under high feed-gas flowrate and achieve high CO 2 uptake under certain conditions. Figure 2c demonstrates the impact of the interaction between temperature and pressure on the CO 2 uptake.…”

“…Particles with a volume fraction (volume of particles/volume of reject brine) of ∼6% were used. The internal diameter, height, and total working volume of the reactor were 0.078 m, 0.850 m, and 3000 mL [18][19][20][21]. In each experiment, a magnetic stirrer was used to mix a certain amount of KOH with 1 L of reject brine.…”

“…To explore the effects of independent variables on the CO 2 uptake and ion removal efficiency, a central composite design (CCD) was employed as an optimization tool for RSM using Minitab 19.0 software [20,22]. To determine the optimum conditions, four process-independent variables were considered, namely, temperature, gauge pressure, KOH concentration, and CO 2 flowrate, and their influence on CO 2 uptake and ion removal percentage (Ca 2+ , Na + , K + , Mg 2+ , and Cl − ) was investigated.…”

Effects of potassium hydroxide and aluminum oxide on the performance of a modified solvay process for CO 2 capture: A comparative study

“…More details about the experimental apparatus can be found in previous studies. 3,4,36,37 The system operated under a semi-batch mode, where the reactor was charged with 1000 mL of a premixed solution consisting of reject brine and alkaline/metal oxide solutions (KOH/Al 2 O 3 ). A magnetic stirrer was used to ensure a uniform distribution of alkaline/metal oxides in the reject brine.…”

A New Process for the Recovery of Ammonia from Ammoniated High-Salinity Brine

“…The method described in this work was evaluated for ammonia recovery from ammonium chloride in a Solvay effluent, wherein a portion of the filtrate from the previous experimental step was reacted with carbon dioxide (CO 2 ) gas (10% vol. and balance air) in a bubble column reactor which was fabricated for previous studies [34,37,[39][40][41][42]. The reaction was run for 24 h in order to ensure the formation of the maximum concentration of ammonium chloride.…”