Flow Field Study On Ventilation System Of Heading Face And Dry Dust Collector

The amount of dust produced in the process of coal mine roadway excavation is much larger than that limit in the “coal mine explosion proof safety regulations”.The dust with high concentration is not only a threat for health of underground staff,but also a hidden trouble for mine safety production,so the control of heading face dust has always been a research focus in mine safety.The efficient solution of heading face dust depends on two aspects.One is dust control technology,that is,efficient ventilation system should be designed to ensure that the dust can be removed by dust removal equipment.The other one is the dust removal technology,that is,the dust into the dust collector can be efficiently disposed.At present,it is still one of the major accidents in coal mines that the ventilation system is not perfect and not reliable.And so far most of the coal mines in our country adopt the wet type dust collector whose dust removal rate is 50%~70%,what's more it's processing capacity of respiratory dust is insufficient,which is easy to cause the deficiency of the pneumoconiosis.So it is of significance to study the heading face ventilation system and the new type dry dust collector for the dust control of the heading face.Aiming at the above problems,for an actual tunnel ventilation system,this paper studied the effect of it's air ducts parameters on dust removal efficiency,so as to provide guidance to improve the removal efficiency of the ventilation system.And the internal flow characteristics of the new mine HBKO1/600 dry dust collector with 99.99% dust removal efficiency was studied,so as to lay the foundation for further research of dry dust collector,which is suitable for coal mine in our country.Specific research contents include the following aspects:Firstly,the basic theory of gas-solid two-phase flow was analyzed,and the governing equations of gas-solid two-phase flow were established.And the mechanism of fiber filtration was analyzed,which lay the theoretical foundation for simulation.On this basis,forcing,exhausting and mixed ventilation systems were studied by experiments in an analog tunnel.And their three-dimensional models were established,the mesh were generated in ICEM,then the software Fluent was used to simulate the ventilation systems.The results show that the simulation results are in agreement with the experimental results,so the correctness of the simulation model,the meshing,the simulation method and the boundary conditions are correct.Based on this in view of an actual drifting tunnel,its different roadway models with far-pressing-near-absorption ventilation system under different air duct parameters were established.The same simulation method is used to simulate the dust treatment of each model The results show that,for the actual drifting tunnel,when the distance of positive-pressing and negative-pressing wide pipes' outlets to working face are respectively 8 m and 2 m,the height of positive-pressing and negative-pressing wide pipes are respectively 2.2 m and 1 m and the diameter of the positive-pressing wide pipe is about 0.6 m,dust removal efficiency near the working face is higher.Finally,the internal flow characteristics of the new mine HBKO1/600 dry dust collector were studied in this paper.The 1:1 three-dimensional model was established in the UG software,and the mesh was generated in ICEM.Then the software Fluent was used to study it's internal trajectory,pressure field and velocity field.The results show that because the dry dust collector adopts the separation structure of upper and lower box,which avoid directly concussion from high velocity airflow of inlet,the velocity and pressure distribution of the the filter elements arranged in lower box are more uniform than that of the conventional bag filter.But the airflow of each filter element is uneven,and this phenomenon is related with the filter element position.Then the flow field characteristics of dust collector under different filtration velocity and filter permeability were studied.The results show that with the increase of filtration velocity,the overall airflow distribution uneven degree in dust collector increases;while the filter element permeability has almost no effect on the airflow and velocity distribution of each filter element,but the lower permeability will bring greater pressure drop inside the dust collector,especially effect the gap of filter elements pressure drop.