| At present,the wet treatment method has the problems of low efficiency of catching respirable dust,high energy consumption cost,easy clogging of nozzles,poor on-site applicability,etc.However,gas-liquid two-phase atomization dust reduction is a strong power method that is not easy to block and is low in cost.However,at present,such technologies and theories at home and abroad lack specificity in the treatment of respirable dust.In particular,there are few related theoretical studies involving supersonic aerodynamic atomization under low air and water pressure,and the meso-kinetics characteristics and dust-catching mechanism are not yet clear.The related basic theories and research methods need to be further enriched and developed.Based on this,this paper proposes to study the meso-kinetics characteristics and dust capture mechanism of supersonic water suction siphon aerodynamic atomization,using a combination of theoretical analysis,numerical simulation,laboratory experiments and field engineering experiments.The main content and the results obtained are as follows:First,through theoretical analysis,a single particle mist-dust collision coupling three-phase flow numerical model in high-speed airflow,a transonic flow model in a compressible airflow nozzle,and a two-dimensional axisymmetrical transonic atomization model in a two-dimensional axisymmetric nozzle were established,and combined with the atomization experiment.The study reveals the reason for the low efficiency of the traditional wet dust reduction method for respirable dust;the best wetting fog-dust particle size ratio k based on water-coal dust is obtained;the linear integral wettability of the dust surface varies with the fog-dust relative The change law of velocity,impact angle,and contact angle;the characteristic parameters of droplet dispersion,velocity and spatial distribution of the aerodynamic spray dust to achieve high-efficiency wetting of respirable dust.Secondly,using the established mathematical model of transonic flow in the compressible airflow nozzle,the distribution law of flow field characteristic parameters such as airflow velocity,pressure and density of four typical Laval nozzles under different aerodynamic total pressures are obtained;When spraying at low pressure as 0.3?0.6MPa,the nozzle achieves the best contraction/expansion ratio,expansion angle and shape parameters for efficient and stable operation.Thirdly,a two-dimensional axisymmetric compressible gas flow nozzle with a numerical model of droplet atomization in transonic flow is established,and a "probe type" liquid phase dispersion method that is different from the traditional "hole type" is proposed,and the inlet aerodynamic system is studied.The influence of pressure,nozzle structure parameters and liquid phase dispersion mode on the atomization process of droplet breaking;the optimal nozzle structure parameters with high atomization efficiency and stability are determined.According to the relationship between the different bases in the paradigm space,the dimensional conversion based on the dimensional transformation of the droplet breaking atomization field characteristic parameter equation set in the transonic flow of the compressible airflow is derived,and the numerical model is established to realize the analysis of the Laval nozzle and its proximity.Three-dimensional characterization and quantitative analysis of field region supersonic atomization and droplet ejection process.Through the comparative study of the atomization spray process in the probe type and the hole type nozzle and the near-field area,the three-dimensional spatial distribution of the fog field characteristics of the two discrete modes are obtained respectively;the transonic atomization in the Laval nozzle and the near-field area is revealed Jet mechanism.Then,the best discrete position of the probe in the nozzle was determined by the atomization experiment.Based on the analysis of the characteristics of the transonic flow field,the atomization and crushing process simulation,and the analysis of the experimental results,the supersonic water-suction siphon aerodynamic atomization method is proposed,and the traditional atomization method is "a high-pressure jet penetrating supersonic airflow atomization."Transformed to "Using supersonic airflow to draw water in a high-speed negative pressure zone for siphon atomization."The supersonic water suction siphon atomization device is developed with the probe nozzle with the best structural parameters as the core,and the distribution law of the meso-kinetics characteristics of the droplets of the atomization device is obtained through experiments;the supersonic water suction siphon aerodynamics is determined Energy consumption parameters and anti-blocking mechanism of the atomization method.Then,through the dust control comparison experiment with the ultrasonic dry fog dust suppression method,the atomization efficiency,particle size distribution,dust reduction efficiency,dust capture meso-kinetics characteristics and the difference of the supersonic water suction siphon aerodynamic atomization method are determined.The classification efficiency of the dispersed dust.Solve the problem that the sprayed droplets are soft and weak due to the dry fog dust suppression method,and it is difficult to efficiently capture coal dust below PM10,and the dust reduction efficiency is limited;according to the atomization characteristics and dust control of the supersonic water suction siphon aerodynamic atomization method Characteristics,revealing the meso-kinetic mechanism of dust catching.Finally,based on the research on the characteristics of supersonic water suction siphon aerodynamic atomization and the meso-kinetics mechanism of dust catching,the applicability of on-site engineering was studied on the first floor of the preparation workshop of the coal preparation plant.According to the established numerical model of airflow-coal dust pollution,the law of coal dust pollution under the influence of field airflow migration and production process is obtained,and on the basis of the previous research results of atomization characteristics and dust catching meso-kinetics mechanism,A dust control system was designed and implemented;the atomization dust reduction effect before and after the system operation was compared and studied,and the whole system realized the low energy consumption,low humidity and good atomization effect to achieve the high-speed aerosol on the blanking port and tail of the belt conveyor.The inner and outer areas of the belt corridor link,as well as the full coverage of coal transportation of more than 100 meters on the coal road,verify the energy-saving and efficient coal dust comprehensive control application effect of this technology.This paper has 123 pictures,20 tables,and 229 references. |
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