Abstract:

A standard 20 L sphere chamber was modified to be adapted for measuring the explosion parameters of hybrid mixtures of ethylene and polyethylene dust. The change rules of the lower flammability limits and explosion severity of the hybrid mixtures were analyzed systematically. The explosion severity of ethylene, polyethylene and their mixtures were compared with each other. The results show that the addition of ethylene induces an obvious decrease in the minimum explosion concentration of polyethylene dust. Mixtures of ethylene below its lower flammability limit and polyethylene dust below its minimum explosion concentration were still explosible. Adding ethylene to polyethylene dust cloud of different concentrations increases both the explosion pressure p_ex and the rate of explosion pressure rise (dp/dt)_ex. But the increase range decreases with the increase of dust concentration. The maximum explosion pressure p_max and explosion index K_st of ethylene and polyethylene mixtures increase with the increase of ethylene concentration. While the maximum explosion pressure p_max and explosion index K_st of the hybrid mixtures of ethylene and polyethylene are higher under all ethylene concentrations than those of the pure polyethylene, but lower than those of the pure ethylene.

Key words: mixtures, flammable gas, powders, explosions, explosion severity, explosion limit

摘要：

基于改进的20 L球形爆炸装置，实验测量了乙烯/聚乙烯两相体系爆炸特性参数，系统地分析了两相体系爆炸下限和爆炸强度变化规律，并对比分析了乙烯、聚乙烯和乙烯/聚乙烯3种体系爆炸强度之间的关系。结果表明：乙烯诱导聚乙烯最小爆炸浓度显著降低，低于爆炸下限的乙烯气体与低于最小爆炸浓度的聚乙烯混合后仍具有爆炸危险性。向不同浓度的聚乙烯粉尘中添加乙烯后，爆炸压力p_ex和压力上升速率（dp/dt）_ex均显著提高，但增幅随粉尘浓度的增大而减小。乙烯/聚乙烯两相体系最大爆炸压力p_max和爆炸指数K_st均随乙烯浓度的增大而增大，但不同乙烯浓度下的两相体系最大爆炸压力p_max和爆炸指数K_st均大于单相聚乙烯粉尘，小于单相乙烯气体。

关键词: 混合物, 可燃气体, 粉体, 爆炸, 爆炸强度, 爆炸极限