Investigations of the effects of two typical jet crushing methods on the atomization and dust reduction performance of nozzles

Single-fuid nozzles and dual-fuid nozzles are the two typical jet crushing methods used in spray dust reduction. To distinguish the atomization mechanism of single-fuid and dual-fuid nozzles and improve dust control efciency at the coal mining faces, the atomization characteristics and dust reduction performance of the two nozzles were quantitatively compared. Results of experiments show that, as water supply pressure increased, the atomization angle of the swirl pressure nozzle reaches a maximum of 62° at 6 MPa and then decreases, but its droplet size shows an opposite trend with a minimum of 41.7 μm. The water supply pressure helps to improve the droplet size and the atomization angle of the internal mixing air–liquid nozzle, while the air supply pressure has a suppressive efect for them. When the water supply pressure is 0.2 MPa and the air supply pressure reaches 0.4 MPa, the nozzle obtains the smallest droplet size which is 10% smaller than the swirl pressure nozzle. Combined with the dust reduction experimental results, when the water consumption at the working surface is not limited, using the swirl pressure nozzle will achieve a better dust reduction efect. However, the internal mixing air–liquid nozzle can achieve better and more economical dust reduction performance in working environments where water consumption is limited.

Exploration on molecular dynamics simulation methods of microscopic wetting process for coal dust

Wet dust removal is one of the main technical measures in coal dust control,and coal dust wetting is the key factor to determine the effect of wet dust removal.In order to explore the micro-wetting process of coal dust,this paper uses molecular dynamics simulation to study the micro-wetting process of coal dust in different simulation conditions.The molecular dynamics simulation was carried out under different ensemble,thermodynamic states as well as relaxation pretreatment methods,then the H_(2)O molecular layer and coal dust molecular layer in each simulation were quantitatively analyzed by relative concentration.The research results show that a method for establishing molecular model of lignite is proposed and the 2D periodic surface structure is more reasonable.The surface system of coal-H_(2)O molecule is established by NVT aeration method,where the simulation result is close to the actual coal dust wetting process.The simulation effect of medium and large coal dust-H_(2)O molecular system is better than that of small coal dust-H_(2)O molecular system.This study provides a new solution for changing the empirical method of molecular dynamics simulation of coal system wetting and oversimplification of coal system.