Prediction of separation density of pulsed fluidized bed based on bidisperse particle characteristics

ABSTRACT

Fluidized bed technology plays a vital role in petroleum, chemical, and coal separation. The dry separation of coarse coals with a particle size of >6 mm has been efficiently achieved using the fluidized bed. However, for fine coal with a particle size of 6–1 mm, ordinary fluidized bed technology is unable to effectively separate it. In light of this issue, the present study incorporates airflow vibration energy into conventional fluidized beds, with a specific focus on the separation process of fine coal. The investigation explores the variation pattern of separation density and delves deep into the influencing factors affecting coal preparation through bed density. A theoretical model for separation density is established based on the characteristics of bidisperse particles, which is subsequently validated and calibrated using dry separation experiments conducted on fine coal. The error is controlled within 10% while achieving a possible deviation E as low as 0.095 g/cm³.

KEYWORDS:

• Gas–solid fluidized bed
• separation density
• coal separation
• gas velocity
• pulsation frequency

Acknowledgements

The research work is financially supported by the National Natural Science Foundation of China (Grants No. 52274275 and No. 52220105008).

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Nomenclature

$x_{\mathit{SH}}$	=	SH particle proportion (-)
$D_p$	=	Particle size (μm)
${\bar{D}}_{\mathit{p}}$	=	Equivalent particle size (μm)
$D_{\mathit{SH}}$	=	SH particle size (μm)
$D_{\mathit{BL}}$	=	BL particle size (μm)
${\bar{d}}_{\mathit{e}}$	=	The mean diameter of bubbles in the bed (m)
$H_{\mathit{mf}}$	=	Bed height at minimum fluidization velocity (m)
H0	=	Initial fixed bed height (m)
u	=	Gas velocity (m/s)
$u_{\mathit{mf}}$	=	Minimum fluidization velocity (m/s)
${\bar{\rho }}_{\mathit{p}}$	=	Equivalent particle density (kg/m3)
${\rho }_{\mathit{SH}}$	=	SH particle density (kg/m3)
${\rho }_{\mathit{BL}}$	=	BL particle density (kg/m3)
${\bar{\rho }}_{\mathit{bed}}$	=	Bed density of the equivalent system (kg/m3)
${\epsilon }_{\mathit{mf}}$	=	Bed voidage at minimum fluidization velocity (-)
ε0	=	Initial fixed bed voidage (-)

Additional information

Funding

The work was supported by the National Natural Science Foundation of China [52274275].