Research On Extracting To The Width Influence Of Goaf Area Oxidation "Three Zones" Under The Condition Of Injecting Nitrogen In Zhenghang Mine

ZhengHang coal mine1502fully mechanized caving face has lots of lose coal amount, which is belong to easy self-ignition coal type, and the feature of these lose coals include higher phosphorus content and sulfur content. Because of higher gas gushing amount from1502working face, ZhengHang coal mine adopt high position drainage technology to ensure working face safety production and prevent upper gas exceeding according to its physical truth. Because of this drainage technology cause negative pressure increasing of goaf, and the negative pressure drainage technology cause air leak increasing of goaf, which is enhancing goaf lose coal hypergolic risk greatly. So it should using pipe laying nitrogen injection to control the width of oxidizing zone while drainage gas. Aim at the high gas and easy hypergolic features of1502working face. The paper firstly analyze the goaf gas transport theory and permeability rule, reach a conclusion that gas discharge of working face mainly derived from high density gas in the goaf, analyzing the goaf overlying rock caving features and crush-expand, porous media porocity featuresof different zone. Combine theory and field observed data, and matching these parameters of oxygen concentration and gas concentration by analyze these data, ensure each basic parameter of goaf, which is offer reliable data for building the three-dimensional numerical model of working face goaf by FLUENT software. The paper simulating the goaf gas concentration field, air leaking fielding and oxygen concentration field under the condition of nitrogen injection by using high drainage technology. Because of the simulative result is approaching to the field measurement data, so it can response the physical truth. The paper reaches the goaf limitation advance speed by analyzing and summarizing these results. Secondly, changing the negative pressure of high drainage roadway under nitrogen injection condition, analyze and study the goaf air leaking field, gas concentration field and oxygen volume fraction after simulation, observing the relation between different negative pressure and upper corner gas density, and building fitted equation, work out the lowest drainage negative pressure under the condition of upper corner gas density is not over limit. According the simulative contour map of air leaking field and oxygen density field in different drainage pressure under the condition of nitrogen injection, the paper reach the relation between different drainage negative pressure and spontaneous combustion zone, and matching the equation. Thus, the paper ensure the best range of high drainage roadway negative pressure which can prevent upper corner gas over-linit and coal spontaneous combustion accidental happens in the goaf.According to the technology of FLUENT simulation, the paper reach the gas distribution law in the goaf intuitive, ensure the change width of three zones, mark out the risk zone of the goaf, evaluating the nitrogen injection effect and drainage negative pressure in the end. Feedback and adjust each parameters in time, perfecting the high drainage roadway fire preventing and extinguishing system under nitrogen injection in the goaf eventually.