马尾松粉尘云最小着火能点火延迟时间的研究

Study of ignition delay time on determining MIE of Pinus Massoniana wood dust cloud explosion

以常规工艺条件下的马尾松(Pinus massoniana)砂光粉(200目筛下混合粒径、含水率8%)为对象,以3个喷粉压力(200kPa、250kPa和300kPa)压缩空气分别对6个质量浓度(500g/m^3、750g/m^3、1000g/m^3、1250g/m^3、1500g/m^3和1750g/m^3)的粉尘进行分散喷吹试验,采用高速摄像获得粉尘在哈特曼管内分散状况,通过帧频图像对粉尘分散均匀性进行评价,确定粉尘均匀分散的瞬间,以此作为测定MIE的点火延迟时间。研究表明:1)试验采用三个喷粉压力在哈特曼管内对6个粉尘浓度进行分散喷吹,能够在极短的瞬间捕捉到理想的分散状态;2)相同的浓度条件下,点火延迟时间随喷粉压力的增大而缩短,喷粉压力分别为200kPa、250kPa和300kPa时,准确点火延迟时间应分别在82～88ms、66～72ms和58～62ms范围;3)在相同的喷粉压力下,浓度增大使得延迟时间先增大后减小。

The Pinus massoniana sanding powder(mixed particle size under 200 mesh sieve and 8% moisture content) under conventional process conditions was used as the object of study. The dispersive spraying tests of dust with six mass concentrations(500g/m^3, 750g/m^3, 1000g/m^3, 1250g/m^3, 1500g/m^3 and 1750g/m^3) were carried out under three injection pressures(200 kPa, 250 kPa and 300 kPa).The dispersion of dust in Hartmann tube was obtained by high-speed camera. The uniformity of dust dispersion was evaluated by frame-frequency image, and the instant of dust uniformity was determined, which was used as the basis for measuring the ignition delay time of MIE. The research shows: 1. the ideal dispersion state can be captured in a very short time by dispersing six different concentrations of dust in Hartmann tube under three injection pressures;2. under the same concentration, the ignition delay time decreases with the increase of the injection pressure while the injection pressure is 200 kPa, 250 kPa and 300 kPa, the accurate ignition delay time should be in the range of 82-88 ms, 66-72 ms and 58-62 ms, respectively;3. at the same injection pressure, the delay time increases first and then decreases with increasing concentration.