Gas and particle circulation in an internally circulating fluidized bed membrane reactor cold model

A multistage riser reactor with the enlarged section plays an increasingly important role in industries such as energy conversion. However, gas−solid complex flow in the multistage riser needs to be further explored. Inner solid circulation occurred in the enlarged section exerts essential effects on flow behavior. In this work, inner circulation mechanisms of solids in the multistage riser are investigated experimentally by correlating the bed geometry. Solid streamline and velocity profiles show that the inner circulation in the enlarged section involves the vortex core part in the upstream region and the expansion part in the downstream region. For the vortex core part, single and dual circulations of solids occur in different enlarged sections. The results also indicate that vortex core motions tend to strengthen with the increase of the diameter ratio and height−diameter ratio but weaken with the increase of the angle. Moreover, the effects of the expansion part on gas−solid flow increase as the angle increases.

Section: Introductionmentioning

confidence: 99%

Experimental Study of the Inner Solid Circulation Pattern in the Multistage Riser

Zhang

2021

“…The conventional gas–solid airlift loop reactor (GSALR) is an important reaction unit and has been widely applied in many industrial processes, such as petroleum coke combustion, − gas–solid dense-phase stripper, − airlift loop heat exchanger, FCC naphtha olefin reformulation, etc. It has a number of outstanding potential advantages including excellent mass and heat transfer rates, high gas–solid contacting efficiency, regulating the residence time and reaction degree flexibly, and simplicity in construction. − …”

Section: Introductionmentioning

confidence: 99%

Solid Holdup and Circulating Velocity in a Novel Airlift High-Speed Loop Reactor for the Methanol to Olefin Reaction

Wang

Wen

et al. 2020

Based on the reaction characteristics of methanol to olefins, a novel high-speed loop reactor (HSLR) is proposed. Distinct hydrodynamics are anticipated to optimize the olefin yield and selectivity. The HSLR mainly comprises a fluidized bed and a draft tube. There are two main regions, i.e., the draft tube and annulus region. The draft tube region is a turbulent/fast fluidized bed where the solids in the reactor flow upward, while the annulus region is a bubbling/turbulent bed where the solids move downward. The solid holdup in the two regions and internal solid circulating velocity is investigated systematically. After dimensionless analysis and continuity of solid flow, calculation models for overall solid holdup in the two regions are established. The ratio of solid circulating flow in the lower loop section ranges from 0.769 to 0.965. In addition, a mathematical model for the internal solid circulating velocity is achieved on the basis of energy equilibrium, and energy dissipation rates are analyzed accordingly.

“…They derived an equation to predict the mean residence time of the biomass particles as a function of the dimensionless mass turnover of the circulating bed material. Recently, Xie et al 11 experimentally evaluated the gas and solid circulation in an ICFB membrane reactor. In their work, the major resistance to solid circulation was found to be at the passage connecting the outer down flow to the inner up flow compartment.…”

Section: Introductionmentioning

confidence: 99%

Coupled Computational Fluid Dynamics and Discrete Element Method Study of the Solid Dispersion Behavior in an Internally Circulating Fluidized Bed

Yang

Luo

Qiu

et al. 2014

The solid dispersion behavior in an internally circulating fluidized bed has been explored on the basis of the calculation results obtained with the computational fluid dynamics-discrete element method coupling approach. The general flow behaviors of gas and solid phases in the bed are presented, and the local dispersion behavior of solid phase is analyzed. Then, the global dispersion intensities in the two chambers of the bed are evaluated. Moreover, the influences of operating parameters and geometrical configuration on solid dispersion are discussed. The results show that the vigorously lateral dispersion of solid phase appears in the right region of the reaction chamber (RC), the region below the baffle, and the upper part of the heat exchanging chamber (HEC). However, the vertical one mainly locates in the RC. Larger global dispersion intensities of solid phase in both the lateral and vertical directions can be obtained in the RC as compared with those of HEC. In each chamber, the vertical dispersion intensity of solid phase is several times of the lateral one. Enlarging the superficial velocity of RC or HEC enhances the lateral and vertical solid dispersion behaviors. More complex response of the dispersion behavior can be obtained with baffle inclined. Increasing the gap height enhances the vertical solid dispersion in both chambers, while the lateral dispersion behavior is enhanced in the RC but suppressed in the HEC.