Gas-solid Flow Behaviors in a Pressurized Multi-stage Circulating Fluidized Bed with Geldart Group B Particles

2019 ◽  
Vol 17 (12) ◽  
Author(s):  
Wei Nie ◽  
Rongtao Feng ◽  
Junguo Li ◽  
Zhenhua Hao ◽  
Haijuan Zhan ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Elevated Pressure ◽  
Operating Pressure ◽  
Gas Velocity ◽  
Cold Model ◽  
Pressure Transducers ◽  
Multi Stage ◽  
Solids Holdup ◽  
Group B

Abstract A comprehensive study of gas-solids flow behaviors was conducted in a novel multi-stage circulating fluidized bed (MCFB). Experiments were carried out in a cold model apparatus (a jetting fluidized bed, JFB, of 0.3 m diameter and 1.95 m tall, a riser of 0.15 m diameter and 12 m tall) at different elevated pressure, solids circulation rates and gas velocities. Geldart group B polystyrene particles of 400 μm in diameter and 1020 kg/m3 in density were used as bed materials. The characteristic of L-valve, axial and radial distributions of solids holdup were systematically tested at elevated pressures by pressure transducers with the frequency of 100 Hz and model PC6M of the optical fiber probes. Operating the L-valve at elevated pressure needs less cross-section average gas velocity compared to that at atmospheric pressure. Experimental results showed that under elevated pressure and high solids flow rate, the MCFB could more easily couple JFB with a riser, where the solids that entered could form three-level step-by-step supplement entrainment and multi-flow regimes formed. Besides, increasing operating pressure led to a higher the apparent solids holdup and local solids holdup. The local solids profiles behaved less uniform distribution at elevated pressure due to decreasing the gas velocity.

Solids Holdup of High Flux Circulating Fluidized Bed at Elevated Pressure

2012 ◽  
Vol 35 (5) ◽  
pp. 904-910 ◽  
Author(s):  
S. Yin ◽  
B. Jin ◽  
W. Zhong ◽  
Y. Lu ◽  
Y. Zhang ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Elevated Pressure ◽  
High Flux ◽  
Solids Holdup

scholarly journals Hydrodynamic experiments on a small-scale circulating fluidized bed reactor at elevated operating pressure, and under an O2/CO2 environment

2017 ◽  
Vol 21 (2) ◽  
pp. 1093-1104 ◽  
Author(s):  
Yerbol Sarbassov ◽  
Azd Zayoud ◽  
Pinakeswar Mahanta ◽  
Sai Gu ◽  
Panneerselvam Ranganathan ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Atmospheric Pressure ◽  
Circulating Fluidized Bed ◽  
Elevated Pressure ◽  
Small Scale ◽  
Operating Pressure ◽  
Hydrodynamic Parameters ◽  
Hydrodynamic Experiments ◽  
Promising Development

Pressurized circulating fluidized bed technology is a potentially promising development for clean coal technologies. The current work explores the hydrodynamics of a small-scale circulating fluidized bed at elevated operating pressures ranging from 0.10 to 0.25 MPa. The initial experiments were performed at atmospheric pressure with air and O2/CO2 environments as the fluidization gas to simulate the hydrodynamics in a circulating fluidized bed. A comparison between the effects of air and O2/CO2 mixtures on the hydrodynamics was outlined in this paper for particles of 160 ?m diameter. A small but distinct effect on axial void-age was observed due to the change in gas density in the dense zone of the bed at lower gas velocity, while only minimal differences were noticed at higher gas velocities. The hydrodynamic parameters such as pressure drop and axial voidage profile along the height were reported at two different bed inventories (0.5 and 0.75 kg) for three mean particle sizes of 160, 302, and 427 ?m and three superficial gas velocities. It was observed that the operating pressure had a significant effect on the hydrodynamic parameters of bed pressure drop and axial bed void-age profiles. The effect of solids loading resulted in an exponential change in pressure drop profile at atmospheric pressure as well as at elevated pressure. The experimental results on hydrodynamic parameters are in reasonable agreement with published observations in the literature.

Gas-solid flow behaviors in a multi-stage circulating fluidized bed under elevated pressure

2019 ◽  
Vol 196 ◽  
pp. 1-13 ◽  
Author(s):  
Feng Rongtao ◽  
Li Junguo ◽  
Dong Libo ◽  
Hao Zhenhua ◽  
Ba Zhongren ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Elevated Pressure ◽  
Solid Flow ◽  
Multi Stage

Gas mixing in a multi-stage conversion fluidized bed (MFB) with secondary air injection. Part I: an experimental study

RSC Advances ◽  
2016 ◽  
Vol 6 (43) ◽  
pp. 36642-36655 ◽  
Author(s):  
Rong Zhang ◽  
Zhenhua Hao ◽  
Zhiyu Wang ◽  
Xiaodong Huo ◽  
Junguo Li ◽  
...  
Keyword(s):  
Experimental Study ◽  
Fluidized Bed ◽  
Air Injection ◽  
Gas Mixing ◽  
Cold Model ◽  
Stage Conversion ◽  
Multi Stage ◽  
Secondary Air Injection ◽  
Secondary Air

This paper investigated the distribution of secondary air after injection into a multi-stage conversion fluidized bed (MFB) cold model.

Solids Flow Pattern in the Bottom Zone of a Rectangular Cross-Section Circulating Fluidized Bed

2003 ◽  
Author(s):  
Hong-Shun Li ◽  
Yi-Jun Wang ◽  
Shi-Ping Jin
Keyword(s):  
Flow Pattern ◽  
Fluidized Bed ◽  
Cross Section ◽  
Quartz Sand ◽  
Circulating Fluidized Bed ◽  
Rectangular Cross Section ◽  
Temperature Response ◽  
Cold Model ◽  
Hot Particles ◽  
Bottom Zone

Solids flow pattern in the bottom zone of a rectangular cross-section CFB was investigated by using hot particles as the tracer. The experiments were carried out in a cold model circulating fluidized bed. The riser has an inner cross-section of 0.3 m by 0.5 m and a height of 5.8 m. The solids were returned into the riser at a height of 0.75 m above the air distributor within an angle of about 40 degree. Quartz sand was used as the bed material. The hot particles were also quartz sand but with a little smaller size. Specially designed miniature electrically heating devices were installed flush with the inner bed wall or inside the bed. At each run, about 10–15 cm3 hot particles were slowly pulled into the bed. The temperature response around the device was measured with four copper-constantan thermocouples. Based on the experimental results, a 3-D core-annulus model describing the solids flow pattern in the bottom zone of the CFB riser is proposed.

Effect of elevated pressure on gas-solid flow characteristics in a circulating fluidized bed

2020 ◽  
Vol 366 ◽  
pp. 470-476 ◽  
Author(s):  
Daoyin Liu ◽  
Jinding Hu ◽  
Jialong Song ◽  
Cai Liang ◽  
Chuanlong Xu ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Flow Characteristics ◽  
Elevated Pressure ◽  
Solid Flow

An Experiment on Solid Circulation Characteristics of a Dual Circulating fluidized Bed Based on Biomaterial Properties and Mechanics Properties

2012 ◽  
Vol 600 ◽  
pp. 261-264
Author(s):  
Teng Ge Mi ◽  
Ying Zhao ◽  
Chang Qing Dong ◽  
Wei Liang Cheng
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Circulation Rate ◽  
Gas Velocity ◽  
Solid Circulation Rate ◽  
Dual Fluidized Bed ◽  
Bed Material ◽  
Circulation Characteristics

In this paper, a dual fluidized bed has been established. The effect of bed material build-up height and gas velocity on the solid circulation rate of CFB (circulating fluidized bed) and BFB (bubble fluidized bed) has been studied. The results show that the solid circulation rate is increased with the increasing of gas velocity Uc and the bed material build-up height. Bed material build-up height of BFB and CFB is changed with the changing of gas velocity Uc. The bed material heights of CFB and BFB have been also investigated in this experiment.

scholarly journals Analysis of Solids Flow Rate through Nonmechanical L-Valve in an Industrial-Scale Circulating Fluidized Bed Using Group B Particles

2018 ◽  
Vol 57 (33) ◽  
pp. 11439-11451 ◽  
Author(s):  
Esmail R. Monazam ◽  
Ronald W. Breault ◽  
Lawrence J. Shadle ◽  
Justin M. Weber
Keyword(s):  
Fluidized Bed ◽  
Flow Rate ◽  
Circulating Fluidized Bed ◽  
Industrial Scale ◽  
Group B

Flow Behaviors in a High-Flux Circulating Fluidized Bed

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
Xiaofang Wang ◽  
Baosheng Jin ◽  
Wenqi Zhong ◽  
Mingyao Zhang ◽  
Yaji Huang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Mass Flux ◽  
Total Pressure ◽  
Slip Velocity ◽  
Circulating Fluidized Bed ◽  
High Flux ◽  
Flow Ratio ◽  
Gas Velocity ◽  
Solids Holdup ◽  
Superficial Gas Velocity

A high-flux circulating fluidized bed coal gasifier cold model which consists of a vertical riser (0.06m-I.D.×5m-high), two downcomers (0.04m-I.D.×3.5m-high and 0.1m-I.D.×3m-high), an inertial separator, a cyclone and two solid feeding devices were established. Geldart group B particles with mean diameters of 140 ?m and densities of 2700 kg/m3 were used as bed materials. Flow behaviors were investigated with the solid mass flux ranges from 108 to 395 kg/m2 and the superficial gas velocity ranges from 7.6 to 10.2 m/s. The pressure drop, apparent solids holdups, average slip velocity and solids-to-air mass flow ratio under different operating conditions were obtained. The results showed that the riser total pressure drop increased sharply with bed height in the low elevation but slowly in the high elevation, since the solids holdup was higher in the low region than that in the high region. The solids holdup increased with the increasing of solids mass flux while it decreased with increasing superficial gas velocity. A dense suspension upflow flow (DSU) structure was found only existing in the low elevation while the rest upper region was still in the dilute phase, and the length of DSU flow structure increased with solids mass flux. The average slip velocity was found to be the strong function of apparent solids holdup; increasing apparent solids holdup leads to the increase of slip velocity. The riser total pressure drop and apparent solids holdup increase with the solids-to-air mass flow ratio.

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