Investigation of optimal selection and atomizing characteristics of nozzles for ultrasonic dry-mist dust suppression system

ABSTRACT

In order to provide insightful guidance for the selection of nozzles and the determination of operating conditions of ultrasonic dry-mist dust suppression system, this study collected six different types of ultrasonic dry-mist nozzles and investigated their atomizing characteristics in depth. Through comparison, the optimal nozzles were applied to engineering site and the dust suppression performance was measured. According to the present research results, the spraying ranges of No. 3, No. 5 and No. 6 nozzles among six different types of nozzles are below 170 cm, suggesting these nozzles are not suitable for far-distance dust suppression. Among the rest three types of nozzles, No. 4 nozzle (ST-47 nozzle) performs best in terms of overall performance, which can not only possess great spraying range but also produce the droplets at the dry-mist level size. Therefore, No. 4 nozzle is applicable to dry-mist dust suppression system in most cases. As the air supply pressure increases, the air flow rate of ST-47 nozzle increases gradually in exponential form while the water flow rate drops exponentially, accompanied with constant increasing ratio of gas-to-liquid flow rate. As the water supply pressure increases, the air flow rate of ST-47 nozzle decreases gradually in exponential form, while the water flow rate increases exponentially, accompanied with constant decreasing ratio of gas-to-liquid flow rate. As regard to the other atomizing parameters, the spraying range increases as the increasing air supply pressure but decreases as the increasing water supply pressure; both the droplet size and atomizing angle decrease as the increasing air supply pressure but increase as the increasing water supply pressure. The optimal operating condition for ST-47 ultrasonic dry-mist nozzle was determined as p_L = 0.1 MPa and p_air = 0.5 MPa. Under that optimal operating condition, the total dust and respirable dust suppression efficiencies after the application of ultrasonic dry-mist dust suppression system during coal transport on the belt can reach up to 94.1% and 96.1%, respectively.

KEYWORDS:

• Ultrasonic dry-mist
• dust suppression system
• nozzle
• optimal selection
• atomizing characteristics

Acknowledgments

This research was financially supported by Natural Science Foundation of Hunan Province (2021JJ30266), Science and Technology Innovation Leading Program of High-tech Industry of Hunan Province (2020GK4101), Science and Technology Progress and Innovation Program of Transportation Department of Hunan Province (202130).

Disclosure statement

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

Author contribution

Xinhu Yuan: methodology, validation Investigation, writing-original draft preparation, visualization.

Pengfei Wang: Conceptualization and writing- review and editing.

Gaogao Wu: data curation.

Shiqiang Chen: review.

Shilin Li: review.

Additional information

Funding

This work was supported by the Natural Science Foundation of Hunan Province [2021JJ30266]; Science and Technology Progress and Innovation Program of Transportation Department of Hunan Province [202130]; Science and Technology Innovation Leading Program of High-tech Industry of Hunan Province [2020GK4101].