同源抽采与混源抽采工况特性量化表征

Quantitative characterization of working condition characteristic between homologous and mixed source extraction

为研究矿井瓦斯同源抽采与混源抽采工况参数差异特性,以底板岩层钻孔、采空区为研究对象,开展不同抽采状态下各主要节点(地面泵站、采区石门、支管孔板、钻孔孔口)抽采负压、体积分数、流量参数获取的现场试验,量化分析并表征同源抽采与混源抽采状态的工况特性。研究表明:管路敷设沿程抽采负压逐级降低,呈指数函数关系,抽采体积分数逐级增大且突增区间一致,抽采流量符合高负压低流量、低负压高流量的抽采特性;同源抽采瓦斯来源单一,抽采负压优势明显,单点敞开式的瓦斯来源是沿程压降的主要致因,当抽采负压提高至有富余能力使外界空气漏入时出现高负压低体积分数抽采,抽采混量近水平线性降低;混源抽采瓦斯来源复杂,多点敞开式瓦斯来源使系统抽采负压、体积分数整体较低,但抽采量补给作用明显,抽采混量逐级降低。同源抽采与混源抽采工况特性量化表征可为煤层瓦斯抽采参数的量化把控和动态调控提供较好支撑。

In order to study the different characteristics of the parameters of the mine gas homologous extraction and mixed source extraction,with floor rock drilling and gob as research objects,field tests on such working condition parameters as negative pressure,concentration and volume under different drainage conditions have been carried out in the main nodes(surface pumping station,mining area Shi men,branch orifice plate,drilling orifice).The research results have shown that negative pressure of pumping decreases gradually,showing an exponential function relationship along the pipeline laying direction and the extraction concentration increases step by step along the course and at the same sudden increase interval.At the same time,drainage flow rate corresponds to high negative pressure with low flow rate and low negative pressure with high flow rate.Gas source of homologous extraction is single so that the advantage of negative pressure is obvious and it is the main cause of pressure drop along the way.High negative pressure with low concentration extraction occurs when drainage surplus capacity increases to the leakage of outside air induced by the increase of negative pressure.The extraction mixing rate decreases slowly and linearly step by step along the pipeline.Gas source of mixed source extraction is complex and the negative pressure and extraction overall concentration will reduce after the multi-point open gas source points are gathered.On the other hand,extraction volume obviously will decrease due to replenishment effect.Quantitative characterization of working condition characteristic between homologous and mixed source extraction provide a better support for the quantitative control and dynamic adjustment of extraction parameters under coal seam gas intelligent extraction mode.