恒温热板加热条件下镁粉尘层的着火规律

研究了在恒温热板加热条件下,热板温度对4种不同粒度镁粉尘层着火规律的影响.主要研究了在临界前、临界时及临界后3种热板温度下镁粉尘层内部的温度分布.结果表明:标准GB/T 16430—1996和IEC 61241-2-1-1994规定的最高热板温度低于镁粉尘层着火的临界热板温度,镁粉尘层不会发生着火,在该加热温度下,不同粒径镁粉尘层在经过较短受热时间后,均达到了温度保持恒定的状态;镁粉粒径越大,镁粉尘层着火时的临界热板温度越高,着火延迟时间越长;热板温度高于临界值时,热板温度越高,粉尘层着火延迟时间越短.

Ignition of Magnesium Powder Dust Layers at Constant Heated Plate

The ignition processes of four types of magnesium powder dust layers at constant heated plate were investigated. In this respect, main concerns are temperature distribution inside magnesium powder layers at precritical, critical, and postcritical temperature of hot plate. The results showed that the ignition of magnesium dust layer would not occur at the maximum temperature of hot plate determined by standards GB/T 16430-1996 and IEC 61241-2-1-1994. The dust layer would come into a long-duration stable temperature after a short period of rising temperature. The critical temperature of hot plate and the ignition delay time increase with particle size. As the temperature of hot plate is larger than the critical one, the higher the temperature of hot plate is, the shorter the ignition delay time of dust layer is.