Study On The High Efficient Ejection Craft For Mine Dedusting Foam

The jet technology now used in the foam de-dusting technology is rather extensive. It is shown in two respects. Firstly, the foam jet flow pattern is not rational, which causes the low utilization rate of foam, part of the foam can not interact with the dust. Secondly, the design of the foam nozzles is rough and lack of basis and pertinence, which lead the foam atomized and fragmentized seriously. And the continuity of the foam flow field is poor. On the basis of prophase investigation, this paper put forward the circular foam flow filed directed against the characteristic of dust producing of longitudinal axial road-header, which is widely used in excavating operation and the foam jet flow pattern used at present. In addition, the design scheme of the new type of foam nozzle aimed at this jet flow pattern was also proposed. Through studying on the structure of road-header and theoretical calculation, the mentality designing and design standard of the new foam nozzle were ensured. Through analysis and comparing in numerical simulation software and experiments, the ideal structure and size of the foam nozzle were determined.The generation procedure and migration characteristics of the dust produced during the extraction process at the micro-level were analyzed. And the inner reason of the dust distribution at macro-level in the underground relative close work space was explained. Moreover, the necessity and superiority of close-dust source treatment technology were pointed out and explained. The advantages of the foam de-dusting technology compared to water mist were explained through comparing. And the dust-settling mechanism and dust suppression mechanism were expounded. Meanwhile, the potentiation of dust migration characteristic and foam de-dusting mechanism was indicated.The usage condition of road-header in field was investigated and the dust production characteristic of the longitudinal axial road-header was analyzed. The deficiencies of the foam jet flow patterns were discussed. The theory of circular-closed foam flow pattern was proposed based on the discussion above. The design schemes of three types of new foam nozzles were came up with and the feasibility of them were analyzed combined with the flow characteristic of the foam. Finally the external guided arc face foam nozzle was chosen. In order to realize annular foam flow field which is form of arc face foam nozzles, two kinds of holder were designed. One of them, the integrated holder contains several spherojoints,which realize the regulation of the foam nozzles installation angle and make the foam flow pattern better. Besides, there is a protection cover which is made of steel around each foam nozzle. It prevents the damage that coal and rock make to the foam nozzle during the excavating operation.The foam flow field was numerical simulated by VOF model in Fluent. And the influence of the foam nozzle main structure sizes on foam flow field was studied. The best structure parameter combination was determined after which the simulation results was statistical analyzed in orthogonal analysis software. Experiments on arc face foam nozzle were conducted in Foam nozzles performance test experimental system. The adjustable external guided arc face foam nozzle and experimental holder were designed and the machining dimension of the arc face foam nozzle was determined. The foam flux distribution test system was designed, and the result concluded that the foam flux distribution of the arc face foam nozzle is relatively even.The field experiments on the new foam nozzle were conducted, and the installation way of foam de-dusting system was designed. In order to investigate the effect of the newly designed foam nozzle, the flat fan foam nozzle and external guided concave arc face foam nozzle were installed separately, and the dust concentrations before and after the foam de-dusting procedure were measured using the individual dust sampler. Then the de-dusting efficiencies of the two types of foam nozzles were calculated. The results showed that the de-dusting efficiencies of external guided concave arc face foam nozzle was 87.2% at the point of the driver position on road-header and 88.9% at the point of 5m back of the driver position on road-header, which both were higher than the de-dusting efficiencies of the flat fan foam nozzle. The results also verified the significant effect of the close-dust source de-dusting treatment.There are 69 figures, 13 tables and 97 references in this paper.